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Chapter 6
Airway
Management
and
Oxygenation
National EMS Education Standard
Anatomy and Physiology
Applies fundamental knowledge of the anatomy and function of all human systems to the practice of EMS.
Pathophysiology
Applies fundamental knowledge of the pathophysiology of respiration and perfusion to patient assessment
and management.
Pharmacology
Applies fundamental knowledge of the medications that the EMT may assist/administer to a patient during
an emergency.
Airway Management, Respiration, and Artificial Ventilation
Applies knowledge of general anatomy and physiology to patient assessment and management to assure a
patent airway, adequate mechanical ventilation, and respiration for patients of all ages.
Review
Perfusion of all cells in the body with oxygen remains the number one priority in patient care. The most critical
patients are those with problems with their “ABCs”: airway, breathing, and circulation. If the patient is unable
to maintain an open airway, insert an oropharyngeal or nasal airway; if he or she is not breathing, provide rescue ventilations; if breathing is difficult or inadequate, provide supplemental oxygenation and consider rescue
ventilations; and if the circulation of blood is absent, perform CPR.
To keep the patient’s airway clear, minimize the risk for aspiration, and prevent fluids and secretions from
being forced into the lungs while ventilating a patient, it may be necessary to suction the patient.
There are many times when a patient needs supplemental oxygenation. The nonrebreathing mask can
deliver high-flow oxygen to the patient, while a nasal cannula provides a lesser amount of oxygen. Artificial
respirations can be provided by using a bag-mask device, a pocket-sized face mask, or a manually triggered
ventilation device.
What’s New
Even as a seasoned EMT, to fully understand the respiratory conditions that a patient may have, it is important
to understand the anatomy and physiology of the respiratory system in detail. In addition, full understanding of
the pathophysiology of ventilation, oxygenation, and respiration will help the EMT better understand the signs
and symptoms associated with certain conditions as well as management techniques for caring for a patient
presenting with such conditions.
In addition to the nonrebreathing mask and the nasal cannula, EMTs now have other oxygen delivery devices available to provide supplemental oxygen to the patient. These devices include the partial rebreathing
mask, the Venturi mask, and the tracheostomy mask. To prevent drying of the mucous membranes in the nose,
humidification of oxygen may be indicated.
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Introduction
Breathing and circulation are two separate but related processes by which oxygen reaches the body’s tissues and cells.
During inhalation, oxygen moves from the atmosphere into
the lungs, then passes from the air sacs in the lungs (alveoli)
into the pulmonary capillaries to oxygenate the blood. At the
same time, carbon dioxide produced by cells in the tissues
of the body moves from the blood into the alveoli through
a process called diffusion. The blood, now enriched with
oxygen, travels through the body by the pumping action of
the heart. The carbon dioxide then leaves the body during
exhalation.
Anatomy of the Respiratory
System: A Review
The respiratory system consists of the various structures
of the body that contribute to the process of breathing
Figure 1 . They include the nose, mouth, throat, larynx,
trachea, bronchi, and bronchioles, which are all air pas-
sages or airways. The respiratory system also includes the
lungs, where oxygen is passed into the blood and carbon
dioxide is removed. Finally, the respiratory system includes
the diaphragm, the muscles of the chest wall, and accessory muscles of breathing, which permit normal respiratory
movement Figure 2 .
The respiratory and cardiovascular systems work
together to ensure that a constant supply of oxygen and
nutrients are delivered to every cell in the body and that
carbon dioxide and waste products are removed from every
cell. When one of these systems is compromised, oxygen
delivery is not effective and cellular death could result.
The process of breathing is typically easy and requires
little muscular effort. But now imagine breathing through a
straw: The smaller the diameter of the straw, the more effort
needed to move air. Thus, as the resistance in the airway
increases, additional muscles—namely, the abdominal and
pectoral muscles—are needed to assist the diaphragm in
moving air.
In the respiratory system, air enters the body through
the oral and nasal cavities, travels into the laryngopharynx,
Nasopharynx
Nasal air
passage
Pharynx
Upper
airway
Oropharynx
Mouth
Epiglottis
Larynx
Trachea
Alveoli
Apex of the lung
Bronchioles
Carina
Main
bronchi
Base of the lung
Lower
airway
Pulmonary
Capillaries
Diaphragm
Alveoli
Figure 1
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The respiratory system consists of the various structures of the body that contribute to the process of breathing.
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Chapter 6 Airway Management and Oxygenation
73
Physiology of the Respiratory
System: A Review
Lung
THORAX
Sternum
Esophagus
While the terms are often used interchangeably, ventilation,
oxygenation, and respiration are three distinct processes. If
a problem arises in any one of these processes, it can affect
other body processes and systems, possibly leading to permanent damage or death table 1 .
Ventilation
Pulmonary ventilation is the process of moving air into and
Vena cava
ABDOMEN
Aorta
Diaphragm
Vertebrae
Costal arch
Figure 2
The dome-shaped diaphragm divides the thorax from
out of the lungs through inhalation and exhalation. It is necessary for oxygenation and respiration to occur. Adequate,
continuous ventilation is essential for life and, therefore,
remains one of the highest priorities in patient care. If the
patient has inadequate or absent breathing, immediate
action is necessary. Signs of inadequate ventilation include
the following:
Pulmonary ventilation The process of moving air into and
out of the lungs through inhalation and exhalation.
the abdomen. It is pierced by the great vessels and the esophagus.
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passes through the vocal cords, moves into the glottis, and
flows down the trachea, where it is distributed through the
mainstem bronchi into the bronchioles of the lungs. This
process occurs because a negative pressure is created in the
chest, as described earlier. Eventually the air reaches the
alveolar sacs, where the oxygen diffuses across the alveolar
membrane into the pulmonary capillaries. At the same time,
carbon dioxide diffuses in the opposite direction across this
membrane and is exhaled from the body. The oxygen in the
pulmonary capillaries is transported to the heart, where it
is distributed to the rest of the body.
At this point, the circulatory system takes over, with
the heart pumping the oxygen-rich blood to the tissues of
the body through a series of arteries and veins. Arteries
carry oxygenated blood away from the heart, branching
into arterioles and capillaries as their distance from the
heart increases. In the capillaries, the exchange of nutrients and waste products takes place. Oxygen and nutrients
leave the capillaries and enter the cells. At the same time,
waste products, such as carbon dioxide, diffuse from the
cells back into the blood of the capillaries. At that point,
the now oxygen-depleted blood travels through a series of
venules that connect to larger veins. All veins carry deoxygenated blood to the heart. The deoxygenated blood enters
the right side of the heart through the right atrium, where it
is pumped through the tricuspid valve, right ventricle, and
pulmonary artery before being sent to the lungs for oxygenation and removal of carbon dioxide. The oxygenated blood
then travels through the pulmonary vein to the left atrium
through the bicuspid valve and into the left ventricle, where
it is again pumped to the rest of the body.
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Altered mental status
Inadequate minute volume (shallow or deep
respirations)
Excessive use of accessory muscles
Fatigue from labored breathing
Cyanosis
Inability to speak in complete sentences (one- or
two-word dyspnea)
Inhalation
Inhalation is the active part of ventilation or breathing, in
which a person takes air into the body through the mouth
and nose. During this process, the diaphragm and intercostal muscles contract, the thoracic cavity enlarges, and
air moves into the trachea and to the lungs via the bronchi,
bronchioles, and eventually the alveoli.
Because the lungs have no muscle tissue, they
can­not move on their own. Instead, they need the help of
other structures to be able to expand and contract during
Table 1
Ventilation, Oxygenation, and Respiration
System
Function
Ventilation
The physical act of moving air
into and out of the lungs through
inhalation and exhalation
Oxygenation
The process of loading oxygen
molecules onto hemoglobin molecules
in the bloodstream
Respiration
The actual exchange of oxygen and
carbon dioxide in the alveoli as well as
in the tissues of the body
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inhalation and exhalation. As such, their ability to function properly depends on the movement of the chest and
supporting structures including the thorax, thoracic cavity (chest), diaphragm, intercostal muscles, and accessory
muscles of breathing.
chioles; this air is called dead space. Alveolar ventilation
is determined by subtracting the amount of dead space air
from the tidal volume.
Alveolar ventilation The volume of air that reaches the
alveoli. It is determined by subtracting the amount of dead
space air from the tidal volume.
Transition Tip
Air can reach the lungs only if it travels through the
trachea. As such, maintaining a clear and open airway
is essential Figure 3 . This is done by removing
obstructing material, tissue, or fluids from the mouth,
nose, and throat so that air can enter and leave the
lungs freely.
Tidal volume is the amount of air that moves into or out
of the lungs during a single breath. It is measured in milliliters (mL). The average tidal volume for a man is approximately 500 mL; of that amount, 150 mL may remain in dead
space and never reach the alveoli for gas exchange.
Minute ventilation, also known as minute volume, is the
amount of air that moves through the lungs in a minute,
minus the dead space. It is calculated as follows:
Minute Ventilation = Tidal Volume
(minus Dead Space) ¥ Respiratory Rate
Minute ventilation The volume of air moved through the
lungs in 1 minute minus the dead space; it is calculated by
multiplying the tidal volume (minus the dead space) and the
respiratory rate. Also referred to as minute volume.
Thus, if the patient is breathing at a rate of 12 breaths/min,
with a tidal volume of 500 mL per breath, the minute volume
would be 4,200 mL (4.2 L). It is important to understand,
however, that minute ventilation is affected by variations in
tidal volume and respiratory rate. For example, if a patient
has shallow respirations, the minute ventilation will be
decreased. Likewise, the minute ventilation will increase if
the patient has deep breathing (increased tidal volume).
Figure 3 Air reaches the lungs only if it travels through
the trachea. Maintaining the airway means keeping the airway
patent so that air can enter and leave the lungs freely.
The air pressure outside the body—that is, the atmospheric pressure—is normally higher than the air pressure
within the thorax. During inhalation, the thoracic cavity
expands, decreasing the air pressure and creating a slight
vacuum. This vacuum pulls air in through the trachea, causing the lungs to fill. When the air pressure equalizes, air
stops moving and inhalation stops.
The entire process of inspiration is focused on delivering
oxygen to the alveoli (alveolar ventilation). However, not
all the air you breathe actually reaches the alveoli. Some air
remains in the mouth, nose, trachea, bronchi, and bron-
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Exhalation
Unlike inhalation, exhalation is a passive process that does
not normally require muscular effort. During exhalation, the
diaphragm and intercostal muscles relax, the thoracic cavity
decreases in size, and air that is in the lungs is compressed
into a smaller space. The air pressure within the thorax is
then higher than the outside pressure, and the air is pushed
out through the trachea.
Vital capacity refers to the amount of air that can be
forcibly expelled from the lungs after breathing deeply.
Even after forceful exhalation, however, it is impossible to
completely empty the lungs of air. The amount of air that
remains—known as the residual volume—averages approximately 1,200 mL in the average adult male. This residual
volume is one of the reasons why CPR can circulate oxygen
without providing ventilations.
Vital capacity The amount of air that can be forcibly
expelled from the lungs after breathing in as deeply as
possible.
Residual volume The air that remains in the lungs after
maximal expiration.
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Chapter 6 Airway Management and Oxygenation
Regulation of Ventilation
The body’s need for oxygen is dynamic, meaning it changes
constantly. The respiratory system must be able to accommodate these changes in oxygen demand by altering the rate
and depth of ventilation. Such changes are regulated primarily by the pH of the cerebrospinal fluid, which is directly
related to the amount of carbon dioxide dissolved in the
plasma portion of the blood. The regulation of ventilation
involves a complex series of receptors and feedback loops
that sense gas concentrations in the body fluids and send
messages to the respiratory center in the brain to adjust the
rate and depth of ventilation accordingly. Failure to meet
the body’s needs for oxygen may result in hypoxia, a dangerous condition in which the tissues and cells of the body do
not receive enough oxygen. If this process is not corrected
quickly, the patient may die.
For most people, the drive to breathe is based on pH
changes (related to carbon dioxide levels) in the blood
and cerebrospinal fluid. However, patients with chronic
obstructive pulmonary disease (COPD) have difficulty
eliminating carbon dioxide through exhalation; thus they
always have higher levels of carbon dioxide. This factor
may potentially alter their drive for breathing because the
respiratory center in the brain gradually accommodates the
high levels of carbon dioxide. In patients with COPD, the
body uses a “backup system” to control breathing called
hypoxic drive, which is based on levels of oxygen dissolved
in plasma. This mechanism differs from the primary control of breathing, which uses carbon dioxide as the driving force. Hypoxic drive is typically found in end-stage
COPD. Providing high concentrations of oxygen over time
will increase the amount of oxygen dissolved in plasma,
which could potentially negatively affect the body’s drive
to breathe.
Hypoxic drive A condition in which chronically low levels
of oxygen in the blood stimulate the respiratory drive; it is
seen in patients with chronic lung diseases.
Because increased oxygen levels could eliminate a
patient’s hypoxic drive, caution should be taken when
administering high concentrations of oxygen to patients
with COPD. At the same time, it is important to remember
that high concentrations of oxygen should never be withheld from any patient who needs it. Patients with severe
respiratory or circulatory compromise should receive high
concentrations of oxygen regardless of their underlying
medical conditions.
Oxygenation
Oxygenation is the process of loading oxygen molecules
onto hemoglobin molecules in the bloodstream. Although
adequate oxygenation is required for internal respiration to
take place, it does not guarantee that internal respiration is
taking place. Oxygenation requires that the air used for ventilation contain an adequate percentage of oxygen. Although
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you generally cannot oxygenate without ventilation, it is
possible to ventilate without oxygenation. This situation
occurs when oxygen levels in the air have been depleted,
such as in mines and confined spaces, and with carbon
monoxide poisoning, where the excess number of carbon
monoxide molecules in the body prevent oxygenation of tissues. Ventilation without adequate oxygenation also occurs
in climbers who ascend too quickly to an altitude of lower
atmospheric pressure. At high altitudes, the percentage of
oxygen remains the same, but the atmospheric pressure
makes it difficult to adequately bring sufficient amounts of
oxygen into the body.
Oxygenation The process of delivering oxygen to the blood
by diffusion from the alveoli following inhalation into the
lungs.
Transition Tip
Oxygenation can be disrupted through carbon monoxide poisoning. Carbon monoxide has a much greater
affinity for hemoglobin than oxygen (250 times more).
As such, carbon monoxide molecules will bind to the
hemoglobin in the red blood cells instead of oxygen
molecules, thereby preventing the proper transport
of oxygen to tissues and ultimately resulting in tissue
death.
Respiration
All living cells perform a specific function and need energy
to survive. Cells take energy from nutrients through a series
of chemical processes. The name given to these processes
as a whole is metabolism (or cellular respiration). During
metabolism, each cell combines nutrients (such as sugar)
and oxygen and produces energy and waste products, primarily water and carbon dioxide. Each cell in the body
requires a continuous supply of oxygen and a regular means
of disposing of waste (carbon dioxide). The body provides
for these requirements through respiration.
Metabolism (cellular respiration) The biochemical processes that result in production of energy from nutrients
within the cells.
Respiration is the process of exchanging oxygen and
carbon dioxide. This exchange occurs by diffusion, during
which a gas moves from an area of higher concentration to
an area of lower concentration. In the body, gases diffuse
rapidly across a short distance of only micrometers, and the
diffusion occurs rapidly Figure 4 .
Respiration The process of exchanging oxygen and carbon
dioxide.
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Alveoli
Pulmonary
capillary
Systemic
capillary
Red blood
cell
Dissolved
O2
CO2 in blood
Dissolved
Interstitial fluid
O2
CO2
O2
CO2
Tissue cells
Plasma
Figure 4 In the capillaries of the lungs, oxygen (O2) passes from the blood to the tissue cells, and carbon dioxide (CO2) and wastes pass from
the tissue cells to the blood. Diffusion occurs when molecules move from an area of higher concentration to an area of lower concentration.
External Respiration
External respiration, also known as pulmonary respiration,
is the process of breathing air into the respiratory system and
exchanging oxygen and carbon dioxide between the alveoli
and the blood in the pulmonary capillaries Figure 5 .
External respiration The exchange of gases between the
lungs and the blood cells in the pulmonary capillaries; also
called pulmonary respiration.
Pulmonary
arteriole
Alveoli
Capillaries
Pulmonary
venule
O2 in
Alveolus
CO2 out
Figure 5
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External respiration.
Capillary
Transition Tip
Air that is inspired into the lungs contains approximately 21% oxygen, 78% nitrogen, and 0.3% carbon
dioxide.
Once the oxygen crosses the alveolar membrane, it is
bound to hemoglobin, an iron-containing molecule that
has a great affinity for oxygen molecules. Through their
presence in red blood cells, hemoglobin molecules low in
oxygen concentration are pumped from the right side of the
heart into the capillaries of the pulmonary circulation. The
capillaries surround alveoli containing high concentrations
of oxygen (from inspired air). The hemoglobin molecules
pick up fresh oxygen as it crosses the alveolar membrane
and transport it back to the left side of the heart, where it is
pumped out to the rest of the body.
Internal Respiration
Internal respiration is the exchange of oxygen and carbon
dioxide between the systemic circulatory system and the
cells of the body. Via its circulation through the body, blood
supplies oxygen and nutrients to various tissues and cells. As
the oxygenated blood travels through the arteries and capillaries, the oxygen passes from the blood in the capillaries
to tissue cells, while carbon dioxide and cell wastes pass in
the opposite direction, from tissue cells through capillaries
and into the veins Figure 6 .
Internal respiration The exchange of gases between the
blood cells and the tissues.
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Chapter 6 Airway Management and Oxygenation
Blood cells
Tissue cells
Capillary
Oxygen and
nutrients in
Carbon dioxide
and waste out
Figure 6
Internal respiration.
Every cell in the body needs a constant supply of oxygen
to survive. Whereas some tissues are more resilient than others, eventually all cells will die if they are deprived of oxygen
Figure 7 . To deliver adequate amounts of oxygen to the
tissues of the body, sufficient levels of external ventilation
and perfusion must take place.
In the presence of oxygen, the mitochondria of the
cells convert glucose into energy through a process known
as aerobic metabolism. Energy in the form of adenosine
triphosphate (ATP) is produced through a series of processes
known as the Krebs cycle and oxidative phosphorylation.
Together, these chemical processes yield nearly 40 molecules
of energy-rich ATP for each molecule of glucose metabolized. Without adequate oxygen, the cells do not completely
TIME IS CRITICAL!
0–1 min: cardiac irritability
0–4 min: brain damage not likely
4–6 min: brain damage possible
6–10 min: brain damage
very likely
More than 10 minutes:
irreversible brain damage
Figure 7 Cells need a constant supply of oxygen to survive.
Some cells may be severely or permanently damaged after going 4 to
6 minutes without oxygen.
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convert glucose into energy, allowing lactic acid and other
toxins to accumulate in the cell. This process, called anaerobic metabolism, cannot meet the metabolic demands of
the cell. Although another intracellular process, glycolysis,
also contributes to ATP production and does not require
oxygen, it results in less ATP production and also produces
lactic acid waste products and toxins. If this process is not
corrected, the cells will eventually die. This phenomenon
explains why adequate levels of perfusion (circulation of
oxygenated blood within an organ or tissue) and external
ventilation must be present for aerobic internal respiration
to take place. However, while these elements are necessary
for internal respiration, they do not guarantee that aerobic
internal respiration will take place.
Aerobic metabolism Metabolism that can proceed only in
the presence of oxygen.
Anaerobic metabolism Metabolism that takes place in the
absence of oxygen; its principal product is lactic acid.
Perfusion The circulation of oxygenated blood within an
organ or tissue.
When the mitochondria within each cell use oxygen to
convert glucose to energy, carbon dioxide—the main waste
product—accumulates in the cell. Carbon dioxide is then
transported through the circulatory system and back to the
lungs for exhalation.
The process of ventilation, oxygenation, and respiration
is an important concept for all EMTs to understand. The
overall goal of these mechanisms is to deliver an adequate
supply of oxygen to the cells of the body. When one of these
processes fails or becomes disrupted, cells die. By recognizing the signs and symptoms of inadequate tissue perfusion
and oxygenation, you can immediately intervene and correct
a potentially life-threatening condition.
Pathophysiology of Respiration
Multiple conditions may inhibit the body’s ability to effectively deliver oxygen to the cells. In turn, disruption of pulmonary ventilation, oxygenation, and respiration will cause
immediate effects on the body. As an EMT, it is important
to recognize these conditions and correct them in a timely
manner.
Factors in the Nervous System
Chemical factors are commonly involved in respiratory control issues because of the level of complexity of the human
body. Complex series of chemical reactions are constantly
taking place. For example, chemoreceptors monitor the levels of oxygen, carbon dioxide, hydrogen ions, and the pH of
the cerebrospinal fluid (CSF), providing feedback on these
parameters to the respiratory centers so that they can modify
the rate and depth of breathing based on the body’s needs
at any given time. Central chemoreceptors in the medulla
respond quickly to slight elevations in carbon dioxide or a
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decrease in the pH of the CSF. The peripheral chemoreceptors, which are located in the carotid arteries and the aortic
arch, are sensitive to decreased levels of oxygen in arterial
blood as well as to low pH levels.
Chemoreceptors Chemical factors that monitor the levels
of oxygen, carbon dioxide, hydrogen ions, and the pH of the
cerebrospinal fluid and provide feedback to the respiratory
centers, which then modify the rate and depth of breathing
based on the body’s needs at any given time.
When serum carbon dioxide or hydrogen ion levels
increase because of medical or traumatic conditions involving the respiratory system, chemoreceptors stimulate the
dorsal and ventral respiratory groups in the medulla to
increase the respiratory rate, thereby removing more carbon dioxide or acid from the body. The dorsal respiratory
group is responsible for initiating inspiration based on the
information received from the chemoreceptors. The ventral
respiratory group is primarily responsible for motor control
of the inspiratory and expiratory muscles.
In addition, the dorsal respiratory group and the ventral
respiratory group are affected by the apneustic center and
the pneumotaxic (pontine) center of the pons. The apneustic
center stimulates the dorsal respiratory group, resulting in
longer, slower respirations. The pneumotaxic center helps
shut off the dorsal respiratory group, resulting in shorter,
faster respirations. If any element of this process is disrupted,
then the respiratory process will be affected.
Ventilation/Perfusion Ratio and
Mismatch
The lung has the functional role of placing ambient air in
close proximity to circulating blood to permit gas exchange
by simple diffusion. To accomplish this action, air and blood
flow must be directed to the same place at the same time. In
other words, ventilation and perfusion must be matched.
A failure to match ventilation and perfusion, or V̇/Q̇ ratio
mismatch, underlies most abnormalities in oxygen and carbon dioxide exchange.
In most patients, the normal resting minute ventilation
is approximately 6 L/min. Nearly one third of this volume
fills dead space; thus resting alveolar ventilation is approximately 4 L/min. By comparison, pulmonary artery blood
flow is approximately 5 L/min. These factors yield an overall
ratio of ventilation to perfusion of 4⁄ 5 L/min or 0.8 L/min.
Because neither ventilation nor perfusion is distributed
equally, both are distributed to dependent regions at rest.
However, the increase in gravity-dependent flow is more
marked with perfusion (blood) than with ventilation (air).
Hence, the ratio of ventilation to perfusion is highest at the
apex of the lung and lowest at the base.
When ventilation is compromised but perfusion continues, blood passes over some alveolar membranes without
gas exchange taking place; as a consequence, not all alveoli
are enriched with oxygen. This failure, in turn, results in a
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lack of oxygen diffusing across the membrane and into blood
circulation. Along the same lines, carbon dioxide is also not
able to diffuse across the membrane and is recirculated in
the bloodstream. This condition results in a V̇/Q̇ ratio mismatch that could lead to severe hypoxemia if this problem
is not recognized and treated.
Similar problems can occur when perfusion across the
alveolar membrane is disrupted. Even though the alveoli
are filled with fresh oxygen, the disruption in the blood
flow does not allow for optimal exchange in gases across
the membrane. As a consequence, less oxygen absorption
in the bloodstream and less carbon dioxide removal occur.
This V̇/Q̇ ratio mismatch can also lead to hypoxemia, with
immediate intervention being necessary to prevent further
damage or death.
Factors Affecting Pulmonary Ventilation
Maintaining a patent airway is critical to the delivery of oxygen to the tissues of the body. Many intrinsic and extrinsic
factors can potentially cause airway obstructions. Intrinsic
factors are those internal to the body; external factors are
those caused by external or environmental conditions.
Intrinsic factors such as infections, allergic reactions,
and unresponsiveness (tongue obstruction) can place significant restrictions on a person’s ability to maintain an open
airway. In fact, swelling from infections and allergic reactions
can be fatal if not aggressively managed with medications
and possibly advanced airway maneuvers. The tongue is
the most common airway obstruction in the unresponsive
patient. This obstruction, while easily corrected, can result
in hypoxia and hinder adequate tissue perfusion. Snoring
respirations and the position of the head and neck are good
indicators that the tongue may be obstructing the airway.
Prompt correction of this obstruction is necessary to ensure
adequate oxygenation.
Some factors affecting pulmonary ventilation are not
necessarily directly part of the respiratory system. Notably,
the central and peripheral nervous systems play key roles in
the regulation of breathing, such that interruptions to these
systems can have a drastic effect on the ability to breathe
efficiently. Medications that depress the central nervous
system, for example, lower the respiratory rate and tidal
volume, thereby decreasing the overall minute volume as
well as alveolar ventilation. As a result, the amount of carbon
dioxide in the respiratory and circulatory systems increases,
leading to an overall increase of carbon dioxide levels in the
bloodstream, a condition known as hypercarbia. Trauma to
the head and spinal cord can also interrupt nervous control
of ventilation, resulting in decreased respiratory function
and even failure of the respiratory cycle. In addition, conditions such as muscular dystrophy can affect nervous control.
Muscular dystrophy causes degeneration of muscle fibers,
resulting in a gradual weakening of muscles, slowing motor
development, and loss of muscle contractility. Curvature of
the spine is also likely in patients with muscular dystrophy
and can impair pulmonary function.
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Chapter 6 Airway Management and Oxygenation
Hypercarbia Increased carbon dioxide levels in the
bloodstream.
Patients with allergic reactions may not only suffer from
a potential airway obstruction from swelling, but may also
have a decrease in pulmonary ventilation from bronchoconstriction. As the bronchioles constrict, air is forced through
smaller lumens, resulting in decreased ventilation. This condition is also found in patients suffering from various forms
of COPD, such as asthma and emphysema.
Extrinsic factors affecting pulmonary ventilation can
include trauma or foreign body airway obstruction. Trauma
to the airway or chest requires immediate evaluation and
intervention. Blunt or penetrating trauma and burns can disrupt airflow through the trachea and into the lungs, quickly
resulting in oxygenation deficiencies. In addition, trauma
to the chest wall can cause structural damage to the thorax, leading to inadequate pulmonary ventilation. Swelling,
punctures, and bruising have a tremendous effect on the
ability to deliver oxygen to the alveoli and into the bloodstream. Proper airway management and high concentrations
of oxygen are crucial to the outcome in these situations.
Factors Affecting Respiration
External elements in the environment can affect the overall
process of respiration. For respiration to take place properly
at the cellular level, both oxygenation and perfusion need
to function efficiently.
External Factors
Adequate respiration requires proper ventilation and oxygenation. External factors such as atmospheric pressure and
the partial pressure of oxygen in the ambient air play a key
role in the overall process of respiration. At high altitudes,
the percentage of oxygen remains the same, but the partial
pressure decreases because the total atmospheric pressure
decreases. The low partial pressure of oxygen can make
it difficult (or impossible) to adequately oxygenate tissue,
interrupting internal respiration. In addition, closed environments, such as mines and trenches, may have lower levels of ambient oxygen, resulting in poor oxygenation and
respiration.
Carbon monoxide, along with other toxic and poisonous gases, displaces oxygen in the environment and makes
proper oxygenation and respiration difficult. Carbon monoxide, in particular, has a much greater affinity for hemoglobin than oxygen (250 times more), so its presence (eg,
in carbon monoxide poisoning) does not allow for proper
transport of oxygen to tissues.
Internal Factors
Conditions that reduce the surface area available for gas
exchange also decrease the body’s oxygen supply, leading
to inadequate tissue perfusion. Medical conditions such as
pneumonia, pulmonary edema, and COPD/emphysema may
also result in a disturbance of cellular metabolism. These
conditions decrease the surface area of the alveoli either by
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damaging the alveoli or by permitting an accumulation of
fluid in the lungs.
Nonfunctional alveoli inhibit the diffusion of oxygen
and carbon dioxide. As a result, blood entering the lungs
from the right side of the heart bypasses the alveoli and
returns to the left side of the heart in an unoxygenated state,
a condition called intrapulmonary shunting.
Drowning victims and patients with pulmonary edema
have fluid in the alveoli. This accumulation of fluid prevents
adequate gas exchange at the alveolar membrane, resulting in decreased oxygenation and respiration. In addition,
exposure to certain environmental conditions, such as high
altitudes, or occupational hazards, such as epoxy resins, over
time can result in fluid accumulation or other abnormal
conditions, causing overall decrease in respiration. These
conditions can interrupt the process of aerobic respiration
at the cellular level, leading to anaerobic respiration and
lactic acid accumulation.
Other conditions affecting cells of the body include
hypoxia, hypoglycemia (low blood glucose), and infection.
As oxygen and glucose levels decrease, the body becomes
unable to maintain a homeostatic balance with regard to
energy production. At this point, the energy production cannot meet the needs of the body, and cellular death is likely
if the condition is not corrected. Infection also increases the
metabolic needs of the body and disrupts homeostasis. If this
problem is not corrected, the cells will die as well.
Circulatory Compromise
For respiration to take place, the circulatory system must
function efficiently to deliver oxygen to the tissues of the
body. When this system becomes compromised, the perfusion of oxygen is not sufficient to meet the oxygen demands
of the tissues.
Obstruction of blood flow to individual cells and tissue is typically related to traumatic injuries, including pulmonary embolism, simple (tension) pneumothorax, open
pneumothorax (sucking chest wound), hemothorax, and
hemopneumothorax. All of these conditions limit the ability of gas exchange to occur at the tissue level as a result of
their effects on the respiratory and circulatory systems. In
addition, conditions such as heart failure and cardiac tamponade inhibit the ability of the heart to effectively pump
oxygenated blood to the tissues.
Blood loss and anemia (a deficiency of red blood cells)
result in a decreased ability of blood to carry oxygen. Without sufficient circulating red blood cells, the hemoglobin
molecules do not have enough sites for binding.
When the body is in a state of shock, oxygen is not delivered to the cells efficiently. Hypovolemic shock consists of an
abnormal decrease in blood volume that causes inadequate
oxygen delivery to body organs. In contrast, shock caused
by vasodilation is not determined by the amount of circulating blood, but rather by the size of the blood vessels. As the
diameter of the blood vessels increases, the blood pressure
in the circulatory system decreases. As the systemic blood
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pressure falls, oxygen is not delivered to the tissues in an
effective manner. Both forms of shock result in poor tissue
perfusion that leads to anaerobic metabolism. Any patient
suspected of being in shock should be treated aggressively
to prevent further interruptions to tissue perfusion. Shock
is discussed in more detail in the Shock and BLS Resuscitation chapter.
Patient Assessment
Recognizing Adequate Breathing
Under normal circumstances, breathing should be a smooth
flow of air moving into and out of the lungs. As a general
rule, unless you are directly assessing the patient’s airway,
you should not be able to see or hear a patient breathe.
Signs of normal (adequate) breathing for adult patients are
as follows:
■■ A normal rate of respirations (between 12 and
20 breaths/min)
■■ A regular pattern of inhalation and exhalation
■■ Clear and equal lung sounds on both sides of the
chest (bilateral)
■■ Regular and equal chest rise (chest expansion) and
fall
■■ Adequate depth of respirations (tidal volume)
■■ Skin that is pink, warm, and dry
sory muscles include the neck muscles (sternocleidomastoid), the chest pectoralis major muscles, and the abdominal
muscles Figure 8 . These muscles are not used during
normal breathing.
Signs of inadequate breathing in adult patients are as
follows:
■■ Respiratory rate less than 8 breaths/min or greater
than 24 breaths/min with poor tissue perfusion
■■ Irregular rhythm, such as the patient taking a series
of deep breaths followed by periods of apnea
■■ Diminished, absent, or noisy auscultated breath
sounds
■■ Reduced flow of expired air at the nose and mouth
■■ Unequal or inadequate chest expansion, resulting in
reduced tidal volume
■■ Increased effort of breathing—use of accessory
muscles
■■ Shallow depth (reduced tidal volume)
■■ Skin that is pale, cyanotic (blue), cool, or moist
(clammy)
■■ Skin pulling in around the ribs or above the clavicles
during inspiration (retractions)
When you are assessing a patient with a potential airway
compromise, consider the external environment. Conditions
Recognizing Abnormal Breathing
An adult who is awake, alert, and talking to you generally has
no immediate airway or breathing problems. Even so, you
should always have supplemental oxygen and a bag-mask
device or pocket mask close at hand to assist with breathing
if its use becomes necessary. A normal breathing rate for an
adult is 12 to 20 breaths/min table 2 .
The adult patient who is breathing more slowly than
normal (fewer than 12 breaths/min) should be evaluated for
inadequate breathing by assessing the depth of his or her
respirations. A patient with a shallow depth of breathing
(reduced tidal volume) may require assisted ventilations,
even if his or her respiratory rate is within normal limits.
A patient with inadequate breathing may appear to be
working hard to breathe. This type of breathing pattern is
termed labored breathing. It requires effort and, especially in
children, may involve the use of accessory muscles. AccesTable 2
Normal Respiratory Rate Ranges
Adults
12 to 20 breaths/min
Children
15 to 30 breaths/min
Infants
25 to 50 breaths/min
Note: These ranges are those identified in the NHTSA 2009
National EMS Education Standards. Ranges presented in
other courses may vary.
09153_ch06_5989.indd 80
Figure 8 The accessory muscles of breathing are used when a
patient is having difficulty breathing, but not during normal breathing.
Notice this patient is in the tripod position.
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Chapter 6 Airway Management and Oxygenation
such as high altitude and enclosed spaces alter the partial
pressure of oxygen in the environment, making the process
of oxygenation difficult for the patient. In addition, poisonous gases, such as carbon monoxide, displace oxygen in the
environment and alter the overall metabolism of the patient.
It is important to recognize these potential situations and
take them into consideration when deciding on appropriate
treatment for the patient.
Assess for agonal respirations—occasional, gasping
breaths that may appear after a patient’s heart has stopped
beating. They occur when the respiratory center in the brain
continues to send signals to the respiratory muscles. These
respirations do not provide adequate oxygen because they
are infrequent, gasping respiratory efforts. In patients with
agonal respirations, artificial ventilation and, most likely,
chest compressions will be necessary.
Some patients may have irregular respiratory breathing
patterns that are related to a specific condition. For example,
Cheyne-Stokes respirations are often seen in patients with
stroke and patients with serious head injuries Figure 9 .
Cheyne-Stokes respirations constitute an irregular respiratory pattern in which the patient breathes with an increasing
rate and depth of respirations that is followed by a period of
apnea, or lack of spontaneous breathing, followed again by
a pattern of increasing rate and depth of respiration.
Serious head injuries may also cause changes in the
normal respiratory rate and pattern of breathing. The
result may be irregular, ineffective respirations that may or
may not have an identifiable pattern (ataxic respirations).
Patients experiencing a metabolic or toxic disorder may display other irregular respiratory patterns such as Kussmaul
respirations—that is, deep, gasping respirations that are
commonly seen in patients with metabolic acidosis.
Although rapid breathing is a compensatory mechanism
to help patients in respiratory distress, some patients are so
ill that their body is not able to compensate for the insufficiency of their respiratory effort. Such patients may look
like they are compensating, but no clinical improvement
will be noticeable. It is essential that you remain vigilant
when monitoring a patient in respiratory distress because
the individual’s condition may decline rapidly.
Cheyne-Stokes breathing
1 min
1 min
Inspiration/expiration
Figure 9 Cheyne-Stokes breathing shows irregular respirations
followed by a period of apnea.
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81
Transition Tip
Patients with inadequate breathing have inadequate
minute volume and need to be treated immediately.
This condition is most easily recognized in patients who
are unable to speak in complete sentences when at rest
(one- or two-word dyspnea) and in those who have a
fast or slow respiratory rate; both of these conditions
may result in a reduction in tidal volume. Emergency
medical care includes airway management, supplemental oxygen, and ventilatory support.
Assessment of Respiration
As described earlier, respiration is the actual exchange of
oxygen and carbon dioxide at the tissue level. Even though
a patient may be ventilating appropriately, the process of
respiration may be compromised. Therefore, assessing for
signs of adequate and inadequate respiration in patients is
essential.
A patient’s level of consciousness and skin color are
excellent indicators of respiration. During normal respiration, oxygen and carbon dioxide diffuse in and out of tissues
and allow aerobic metabolism to take place. During assessment of the brain and skin tissues, it will be apparent if the
patient has adequate oxygen levels reaching these areas. A
patient presenting with an altered level of consciousness may
not have adequate oxygen levels reaching the brain; this lack
of oxygen can cause rapid changes in the patient’s mental
status. Therefore, when treating patients with an altered
mental status, always consider the possibility that they might
not be getting adequate oxygen levels to their brain and that
you might need to address the possible underlying causes.
Keep in mind, however, that you must determine the baseline mental status on the patient. Some patients naturally
have an abnormal mental status because of a previous medical condition. Ask family members to describe the patient’s
normal mental condition for use as a comparison state.
Just as an altered level of consciousness is indicative of
inadequate respiration, the same is true for patients with
poor skin color. When oxygen fails to reach the skin tissue
of the body, because of either a lack of perfusion or poor
oxygenation, the color of the skin changes to reflect the poor
level of oxygenation. Pale skin and mucous membranes,
commonly referred to as pallor, are typically associated with
poor perfusion caused by illness or shock. As this condition worsens, cyanosis becomes noticeable first peripherally,
in the fingertips, and then centrally, in the mucous membranes and around the lips Figure 10 . Eventually, if the
poor perfusion or oxygenation is not corrected, anaerobic
metabolism will take place. It could cause the skin to become
marked with blotches of different colors, commonly referred
to as mottling.
Although a patient’s baseline mental status and the
color of the skin and mucous membranes represent good
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indicators of respiration, EMTs should also consider proper
oxygenation when assessing patients. As mentioned earlier,
oxygenation is the process of loading oxygen molecules onto
hemoglobin molecules in the bloodstream. Several methods
can be used to assess proper oxygenation, including assessing skin color and mental status and the more recent use
of pulse oximetry.
Oxygen saturation (Spo2) is the measurement of the
percentage of hemoglobin molecules that are bound in arterial blood. Because hemoglobin delivers 97% of the oxygen
delivered to the body’s tissues, the oxygen saturation rate is
an excellent indication of the amount of oxygen available
to the end organs.
In the past few years, the pulse oximeter has become
standard equipment in the treatment of emergency patients.
This device provides a rapid, reliable, noninvasive, realtime indication of respiratory efficiency. Although its results
should not be used without conducting an overall clinical
assessment of the patient, careful use of the pulse oximeter
provides valuable information about a patient’s oxygenation
status. This device can be used both to assess the adequacy
of oxygenation during positive-pressure ventilation and to
assess the overall impact of interventions on your patient.
A pulse oximeter measures the percentage of hemoglobin saturation. Under normal conditions, the Spo2 should be
95% to 100% while a person is breathing room air. Although
no definitive threshold for normal values exists, an Spo2 of
less than 96% in a nonsmoker may indicate hypoxemia. A
value between 91% and 94% indicates mild hypoxemia; 80%
to 90% indicates significant hypoxemia; and less than 85%
indicates profound hypoxemia. Oxygen delivery should be
titrated to a minimum Spo2 of 95% unless the patient has a
chronic condition causing perpetually low oxygen saturations, without signs of respiratory distress. Follow local protocols. Pulse oximeters are highly reliable in Spo2 readings
above 85%; readings of less than 85%, while considered less
reliable, certainly indicate profound hypoxemia.
Pulse oximetry is considered a routine vital sign and
can be used as part of any patient assessment. Although
there are no true contraindications to use of pulse oximetry,
EMTs must be aware of the limitations associated with this
device.
In patients with significant vasoconstriction or very low
perfusion states (including cardiac arrest), there may not be
enough peripheral perfusion to be detected by the sensor. In
these cases, you should move the sensor to a more central
location (eg, the bridge of the nose or an ear lobe). Always
consult the manufacturer’s guidelines for proper placement
and troubleshooting of these devices. An inaccurate pulse
oximetry reading may be caused by any of the following
conditions:
■■ Hypovolemia
■■ Anemia
■■ Severe peripheral vasoconstriction (chronic hypoxia,
smoking, or hypothermia)
■■ Time delay in detecting respiratory insufficiency
■■ Dark or metallic nail polish
■■ Dirty fingers
■■ Carbon monoxide poisoning
Transition Tip
When carbon monoxide is present in the inspired gas,
it displaces oxygen from the hemoglobin. Pulse oximetry, which measures hemoglobin saturation, is unable
to distinguish between oxygen saturation and carbon
monoxide saturation. Thus, in cases of carbon monoxide poisoning, even though the circulating oxygen
levels are poor, the Spo2 reading will be normal.
Transition Tip
The pulse oximeter is a valuable adjunct to aid in decision making, but it is not a replacement for a complete
assessment. For many different reasons, the pulse oximeter may give falsely high or low readings.
Supplemental Oxygen
Figure 10 Skin color can provide an early, fast indication of several
disease processes. This photo shows cyanosis.
09153_ch06_5989.indd 82
In hypoxia, not enough oxygen is getting to the tissues and
cells of the body. Thus all patients who are hypoxic should
receive supplemental oxygen. Some tissues and organs,
such as the heart, central nervous system, lungs, kidneys,
and liver, require a constant supply of oxygen to function
normally. Supplemental oxygen should be administered to
any patient with potential hypoxia, regardless of his or her
clinical appearance.
An ongoing debate has focused on how much supplemental oxygen a patient requires. In some EMS systems, immediate high-flow oxygen is given to any trauma
patient. Other systems require a full assessment prior to
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Chapter 6 Airway Management and Oxygenation
making a determination of the patient’s oxygen needs.
Make sure to know your local protocols regarding oxygen
administration.
83
need to be kept upright and have special requirements for
filling, large-volume storage, and cylinder transfer.
Oxygen-Delivery Equipment
Transition Tip
Never withhold oxygen from any patient who might
benefit from it, especially if you must assist ventilations. When you are ventilating any patient in cardiac
or respiratory arrest, always use high-concentration
supplemental oxygen.
Traditionally, the oxygen-delivery equipment used in the
field has been limited to nonrebreathing masks, bag-mask
devices, and nasal cannulas. Today, however, some other
devices are available to the EMT, including the partial
rebreathing face mask, Venturi mask, and tracheostomy
mask. The use of humidification is also new to the EMT.
Nonrebreathing Masks
Oxygen Cylinders
Oxygen has traditionally been stored in seamless steel or
aluminum cylinders of various sizes Figure 11 . As an EMT,
you should be familiar with the various sizes of cylinders,
safety considerations, and operating procedures when providing supplemental oxygen using an oxygen cylinder.
The nonrebreathing mask is the preferred way of giving oxygen in the prehospital setting to patients who are breathing
adequately but are suspected of having or showing signs of
hypoxia Figure 12 . With a good mask-to-face seal, this
device is capable of providing as much as 90% inspired
oxygen at a flow rate of 10 to 15 L/min.
Liquid Oxygen
Transition Tip
Liquid oxygen is oxygen that has been cooled to a liquid
state. When warmed, it converts to a gaseous state. Liquid
oxygen is becoming more commonly used as an alternative
to compressed gas oxygen. Liquid oxygen containers tend to
be more expensive than compressed oxygen tanks; however,
the containers hold a large volume of oxygen and do not
need to be filled as often. Liquid oxygen units also weigh
less than aluminum or steel tanks. For these reasons, many
people who receive long-term oxygen therapy use liquid
oxygen units. Unfortunately, liquid oxygen tanks generally
Ensure that the reservoir bag of the nonrebreathing
mask is full before you place the mask on the patient.
If oxygen therapy is discontinued, remove the mask
from the patient’s face. Leaving the mask in place, while
oxygen is not flowing, allows the patient to rebreathe
exhaled carbon dioxide.
Figure 11 Oxygen tanks are made of steel or aluminum and come
in various sizes.
09153_ch06_5989.indd 83
Nasal Cannulas
A nasal cannula delivers oxygen through two small, tubelike
prongs that fit into the patient’s nostrils Figure 13 . This
device can provide 24% to 44% inspired oxygen at a flow
rate of 1 to 6 L/min. For the comfort of your patient, flow
rates greater than 6 L/min are not recommended with the
nasal cannula.
Figure 12 The nonrebreathing mask contains flapper valve ports
at the cheek areas of the mask to prevent the patient from rebreathing exhaled gases.
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Figure 13 The nasal cannula delivers oxygen directly through
the nostrils.
Transition Tip
The nasal cannula delivers dry oxygen directly into
the nostrils, which, over prolonged periods, can cause
dryness or irritate the mucous membrane lining of the
nose. For this reason, you should consider the use of
humidification during prolonged transport times.
A nasal cannula is used for patients who simply cannot
tolerate a nonrebreathing or partial rebreathing mask, and
for patients who are not critical but may benefit from lower
concentrations of oxygen. It is also useful when transporting a noncritical patient who is on home oxygen via a nasal
cannula.
Partial Rebreathing Masks
The partial rebreathing mask is similar to a nonrebreathing mask except that it lacks a one-way valve between
the mask and the reservoir Figure 14 . Consequently,
patients rebreathe a small amount of their exhaled air. This
arrangement has some benefit when you want to increase
Figure 15 The Venturi mask.
the patient’s partial pressure of carbon dioxide, making this
device the ideal mask for patients who may develop hyperventilation syndrome. The oxygen enriches the air mixture
and delivers a gas mixture consisting of approximately 80%
to 90% oxygen and 2% to 3% carbon dioxide. You can easily convert a nonrebreathing mask to a partial rebreathing
mask by removing the one-way valve between the mask and
the reservoir bag.
Venturi Masks
A Venturi mask has a number of attachments that enable
you to vary the percentage of oxygen delivered to the patient
while a constant flow is maintained from the regulator
Figure 15 . This delivery is accomplished by exploiting
the Venturi principle, which causes air to be drawn into the
flow of oxygen as it passes a hole in the line. The Venturi
mask is a medium-flow device that delivers 24% to 40%
oxygen, depending on the manufacturer’s settings.
The main advantage of the Venturi mask is its fine
adjustment capabilities, which has benefits in the long-term
management of physiologically stable patients. When it is
necessary to adjust the oxygen concentration in an emergency, the health care provider typically changes either the
flow rate or the delivery device.
Tracheostomy Masks
Figure 14 A partial rebreathing mask.
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Patients with tracheostomies do not breathe through their
mouth and nose. As such, a face mask or nasal cannula
cannot be used to provide supplemental oxygen to these
individuals. Tracheostomy masks are specially designed to
cover the tracheostomy hole, with a strap that goes around
the neck. These masks are usually available in intensive
care units, where many patients have tracheostomies, but
may not be available in an emergency setting. If you do not
have a tracheostomy mask, you can improvise by placing a
face mask over the stoma. Even though the mask is shaped
to fit the face, you can usually get an adequate fit over the
patient’s neck by adjusting the strap Figure 16 .
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Chapter 6 Airway Management and Oxygenation
85
tidal volume) are typically unable to speak in complete
sentences without becoming winded. These patients, in
addition to those with an irregular breathing pattern, may
require artificial ventilation to help them maintain adequate
minute volume.
Transition Tip
Figure 16 If a tracheostomy mask is not available, use a face mask
instead.
Humidification
Although dry oxygen is not considered harmful for shortterm use, when longer transport times are expected, the use
of humidified oxygen may be beneficial to the patient to
prevent drying of the nasal mucosa. An oxygen humidifier
consists of a small bottle of water through which the oxygen
leaving the cylinder becomes moisturized before it reaches
the patient Figure 17 . Because the humidifier must be
kept in an upright position, however, it is practical only for
the fixed oxygen unit in the ambulance.
Assisted and Artificial Ventilation
A patient who is not breathing needs artificial ventilation
with 100% supplemental oxygen. Assisted
and artificial ventilation are probably the
most important skills in
EMS—at any level. Too
often emphasis is placed
on advanced airway
techniques, making the
basic airway maneuvers
seem ineffective. This
perception could not be
further from the truth:
Basic airway and ventilation techniques are
extremely effective when
administered appropriately. Mastery of these
techniques at the EMT
level is imperative.
Figure 17 Giving humidified
Patients who are
oxygen may be preferred with long
breathing
inadequately
transport times. However, this type of
(too
rapidly
or too
oxygen delivery system is not universlowly with reduced
sally available in all EMS systems.
09153_ch06_5989.indd 85
Shallow breathing can be just as dangerous as very
slow breathing. Fast, shallow breathing moves air primarily in the larger airway passages (dead air space)
and does not allow for adequate exchange of air and
carbon dioxide in the alveoli. Patients with inadequate
breathing require assisted ventilations with some form
of positive-pressure ventilation. Remember to follow
standard precautions when managing the patient’s
airway.
Assisting Ventilation in Respiratory
Distress/Failure
A patient exhibiting signs of severe respiratory distress or
respiratory failure requires immediate intervention. Two
treatment options are available in these situations: assisted
ventilation via a bag-mask device and continuous positive
airway pressure (CPAP).
The purpose of assisted ventilations is to improve the
overall oxygenation and ventilatory status of the patient.
Patients who require assisted ventilation are no longer
able to maintain adequate oxygen levels for the body and
need intervention to prevent further hypoxia. Indicators of
inadequate ventilation include altered mental status and
inadequate minute volume. In addition, excessive accessory
muscle use and fatigue from labored breathing are signs of
potential respiratory failure. table 3 lists the recommended ventilation rates for apneic patients with a pulse.
Follow these steps to assist a patient with ventilations
using a bag-mask device:
1. Explain the procedure to the patient.
2.Place the mask over the patient’s nose and mouth.
3.Squeeze the bag each time the patient breathes,
maintaining the same rate as the patient.
4.After the initial 5 to 10 breaths, slowly adjust the rate
and deliver an appropriate tidal volume.
Table 3
Ventilation Rates for an Apneic Patient With
a Pulse
Adult
1 breath every 5 seconds
Child
1 breath every 3 seconds
Infant
1 breath every 3 seconds
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in the treatment of respiratory distress associated with
obstructive pulmonary disease and acute pulmonary edema.
Its use has negated the need for advanced airway devices
such as the endotracheal tube, and decreased morbidity and
mortality associated with conditions needing such intubation. CPAP is not a new skill to the EMT and, therefore, is
not discussed further in this text.
Artificial Ventilation
Figure 18 Many people who have been diagnosed with obstructive sleep apnea wear a CPAP device at night to maintain their airway
while they sleep.
5.Adjust the rate and tidal volume to maintain an
adequate minute volume.
Continuous Positive Airway Pressure
Continuous positive airway pressure is a noninvasive means
of providing ventilatory support to patients who are experiencing respiratory distress in which their own compensatory
mechanisms are not sufficient to keep up with their oxygen
demand Figure 18 . Although most patients improve after
the application of CPAP, it is important to remember that this
technique merely treats the symptoms; it does not necessarily address the underlying pathology.
Over the past several years, the use of CPAP in the prehospital environment has proved to be an excellent adjunct
Patients who are in respiratory arrest need immediate intervention. Without it, they will die. Devices for providing
artificial ventilation include the pocket face mask for performing mouth-to-mask ventilations, the bag-mask device,
and the manually triggered ventilation device.
Normal Ventilation Versus Positive-Pressure
Ventilation
Although artificial ventilations are necessary to sustain life,
they are not the same as normal breaths. As discussed earlier, the act of air moving in and out the lungs is based on
pressure changes within the thoracic cavity. During normal
ventilation, the diaphragm contracts and negative pressure
is generated in the chest cavity. In response, air is essentially sucked into the chest from the trachea in an attempt
to equalize the pressure in the chest with the atmospheric
pressure. In contrast, positive-pressure ventilation generated by a device, such as a bag-mask device, forces air into
the chest cavity from the external environment, rather than
based on pressure changes. This difference between normal
ventilation and positive-pressure ventilation can create some
challenges for the EMT table 4 .
Table 4
Normal Ventilation Versus Positive-Pressure Ventilation
Normal Ventilation
Positive-Pressure Ventilation
Air movement
Air is sucked into the lungs due to
Air is forced into the lungs through a means of mechanical
the negative intrathoracic pressure ventilation.
created when the diaphragm
contracts.
Blood movement
Normal breathing allows blood
to naturally be pulled back to the
heart.
Intrathoracic pressure is increased, not allowing blood
to be adequately pulled back to the heart. This causes a
reduction in the amount of blood pumped by the heart.
Airway wall pressure
Not affected during normal
breathing.
More volume is required to have the same effects as
normal breathing. As a result, the walls are pushed out of
their normal anatomic shape.
Esophageal opening
pressure
Not affected during normal
breathing.
Air is forced into the stomach, causing gastric distention
that could result in vomiting and aspiration.
Overventilation
Overventilation is not typical of
normal breathing.
Forcing the volume and rate results in increased
intrathoracic pressure, gastric distention, and decrease in
cardiac output (hypotension).
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Chapter 6 Airway Management and Oxygenation
The physical act of the chest wall expanding and retracting during breathing serves to aid the circulatory system in
returning blood back to the heart. During normal ventilation, the chest wall movement works similar to a pump. The
pressure changes in the thoracic cavity help draw venous
return back to the heart.
When positive-pressure ventilation is initiated, however, more air is needed to achieve the same oxygenation
and ventilatory effects that occur during normal breathing.
This increase in airway wall pressure pushes the walls of
the chest cavity out of their normal anatomic shape. As a
result, the overall intrathoracic pressure within the chest
cavity increases. This increased pressure, in turn, causes a
decrease in blood flow, resulting in poor venous return to
the heart and a reduction in the amount of blood pumped
out of the heart. Cardiac output (CO) is a function of stroke
volume and heart rate:
Cardiac Output (CO) = Stroke Volume ¥ Heart Rate
Cardiac output The amount of blood ejected by the left
ventricle in 1 minute.
Stroke volume is the amount of blood ejected by the ventricle
in one cardiac cycle or one beat. The heart rate is assessed
by taking the pulse for 1 minute. The CO is the amount of
blood ejected by the left ventricle in 1 minute.
Stroke volume The volume of blood pumped forward with
each ventricular contraction.
Transition Tip
To prevent a drop in cardiac output, it is imperative
that the EMT regulate the rate and volume of artificial
ventilations.
87
Figure 19 A manually triggered ventilation device can provide
as much as 100% oxygen.
Manually Triggered Ventilation Devices
Another method of providing artificial ventilation is with
a manually triggered ventilation device Figure 19 . Such
devices—which are also known as flow-restricted, oxygenpowered ventilation devices or demand valves—have been
widely available for use in EMS systems for several years,
although they have not been widely used.
The major advantage associated with this device is that it
allows a single rescuer to use both hands to maintain a maskto-face seal while providing positive-pressure ventilation. It
also reduces the rescuer fatigue associated with using a bagmask device on extended transports. Nevertheless, recent
findings suggest that manually triggered ventilation devices
are associated with difficulty in maintaining adequate ventilation without assistance and should not be used routinely
because of the high incidence of gastric distention and possible damage to structures within the chest cavity. Another
disadvantage is that a special unit and additional training
are required when using the manually triggered ventilation
device on infants and children.
Transition Tip
Another difference between normal ventilation and
positive-pressure ventilation relates to the control of airflow.
When a person breathes normally, air enters the trachea, but
generally not the esophagus. In contrast, the force generated from positive-pressure ventilation allows air to enter
both the trachea and the esophagus. Ventilations that are
too forceful can lead to gastric distention (excessive air in
the stomach).
The manually triggered ventilation device should not
be used on patients with chronic obstructive pulmonary disease or with suspected cervical spine or chest
injuries. This device is typically used only on adult
patients. Additional training is necessary prior to using
the device on pediatric patients.
illustrates the sequence for ventilating
an apneic patient using the manually triggered ventilation
device:
1 Choose the proper mask size to seat the mask from
the bridge of the nose to the chin. (Step 1)
skill drill 1
Transition Tip
Mouth-to-mouth, mouth-to-mask, and bag-mask ventilations are all skills that you should have mastered
by now.
09153_ch06_5989.indd 87
2
Position the mask on the patient’s face by the most
appropriate method. (Step 2)
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3
Open the patient’s airway and hold the mask in place
with one hand, maintaining an adequate mask-toface seal. (Step 3)
4
5
Press the ventilation button until you see visible chest
rise. (Step 4)
Allow the patient to exhale passively. (Step 5)
Skill Drill 1
Manually Triggered Ventilation Device for Apneic Patients
1
3 Open the patient’s airway and hold the mask with
5 Allow the patient to exhale passively.
Choose the proper mask size to seat the mask from
the bridge of the nose to the chin.
one hand.
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2 Position the mask on the patient’s face by the most
4 Press the ventilation button until you see visible
appropriate method.
chest rise.
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Chapter 6 Airway Management and Oxygenation
1
skill drill 2
shows the steps for administering
supplemental oxygen to a spontaneously breathing patient
with the manually triggered ventilation device:
Prepare your equipment by attaching the appropri-
ate-sized mask to the manually triggered ventilation
device and ensuring that it is connected to an oxygen
source. (Step 1)
Transition Tip
The Sellick maneuver, also known as cricoid pressure,
has been used to inhibit the flow of air into the stomach
(thereby reducing gastric distention) and to reduce the
chance of aspiration by helping block the regurgitation
of gastric contents from the esophagus. It has also
been used to improve visualization of the vocal cords
or positioning of the lighted stylet during intubation.
In this maneuver, an EMT applies cricoid pressure on
the patient by placing the thumb and index finger on
either side of the cricoid cartilage (located at the inferior border of the larynx) and pressing down.
According to several studies cited in the 2010 American Heart Association Guidelines, cricoid pressure may
actually impede ventilation and not completely prevent
aspiration. For this reason, the procedure is generally
not recommended. Be sure to follow your local protocol
regarding the use of the Sellick maneuver.
89
2
Whenever possible, have the patient hold the mask to
his or her own face to maintain a good seal. (Step 2)
3
When the patient inhales, the negative pressure cre-
ated will trigger the valve within the manually triggered ventilation device and deliver 100% oxygen.
Automatic Transport Ventilator/Resuscitator
The automatic transport ventilator (ATV) is essentially a
manually triggered ventilation device attached to a control
box that allows the user to set the variables of ventilation
Figure 20 . Although an ATV lacks the sophisticated control of a hospital ventilator, it frees the EMT to perform other
tasks, such as maintaining a mask seal or ensuring continued
patency of the airway. You can even perform non–airwayrelated tasks if the patient has an advanced airway in place
and is being ventilated with the ATV. However, even though
an ATV is helpful to an EMT, a bag-mask device and mask
should always be prepared and ready for use should a malfunction occur with the ATV.
Skill Drill 2
Manually Triggered Ventilation for Conscious, Spontaneously Breathing
Patients
1
Prepare your equipment.
09153_ch06_5989.indd 89
2 Whenever possible, have the
patient hold the mask to his
or her own face to maintain a
good seal.
3 When the patient inhales, the
negative pressure created will
trigger the valve within the
manually triggered ventilation
device and deliver 100%
oxygen.
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Figure 20 Automatic transport ventilator (ATV).
09153_ch06_5989.indd 90
Like the manually triggered ventilation device, the ATV
is generally oxygen powered, although some models may
require an external power source. This device generally consumes 5 L/min of oxygen; by comparison, a bag-mask device
requires 15 to 25 L/min of oxygen. In addition, just like the
manually triggered ventilation device, the ATV includes a
pressure relief valve, which can lead to hypoventilation in
patients with poor lung compliance, increased airway resistance, or airway obstruction. Compliance is the ability of the
alveoli to expand when air is drawn in during inhalation;
poor lung compliance is the inability of the alveoli to fully
expand during inhalation.
Although use of an ATV potentially frees the EMT to
perform other tasks, constant reassessment of the patient is
necessary. Barotrauma is a common complication associated
with manually triggered ventilation devices and the ATV. In
addition, the EMT needs to assess for full chest recoil when
using an ATV. This step is not only essential with patients
in respiratory arrest, but also with patients in cardiac arrest
receiving chest compressions.
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To fully understand the respiratory conditions a patient
may have, the EMT must understand the anatomy and
physiology of the respiratory system in more detail.
Understanding the pathophysiology of ventilation, oxygenation, and respiration will also help the EMT better
understand the signs and symptoms associated with
certain conditions as well as management techniques for
caring for a patient presenting with such conditions.
The respiratory system comprises all the structures of
the body that contribute to the process of breathing,
including the nose, mouth, throat, larynx, trachea,
bronchi, and bronchioles. All of these structures are
all air passages or airways. The respiratory system also
includes the lungs, the diaphragm, the muscles of the
chest wall, and accessory muscles of breathing.
The respiratory and cardiovascular systems work
together to ensure that a constant supply of oxygen
and nutrients is delivered to every cell in the body and
that carbon dioxide and waste products are removed
from every cell.
During inhalation, oxygen moves from the atmosphere
into the lungs, then passes from the air sacs in the lungs
(alveoli) into the capillaries to oxygenate the blood. At
the same time, carbon dioxide produced by cells in
the tissues of the body moves from the blood into the
alveoli through a process called diffusion. The blood,
once enriched with oxygen, travels through the body
by the pumping action of the heart. The carbon dioxide
ultimately leaves the body during exhalation.
In the circulatory system, the heart pumps blood to
the tissues of the body through a series of arteries and
veins. Arteries carry oxygenated blood away from the
heart and branch into arterioles and capillaries. Veins
carry deoxygenated blood to the heart.
Although the terms are often used interchangeably, ventilation, oxygenation, and respiration are actually three
distinct processes.
•• Ventilation is the physical act of moving air into and
out of the lungs.
•• Oxygenation is the process of loading oxygen
molecules into hemoglobin molecules in the
bloodstream.
•• Respiration is the actual exchange of oxygen and
carbon dioxide in the alveoli as well as the tissues
of the body.
Cells take energy from nutrients through a series of
chemical processes called metabolism or cellular
respiration.
During metabolism, each cell combines nutrients (such
as sugar) and oxygen and produces energy and waste
products (primarily water and carbon dioxide). Each
cell in the body requires a continuous supply of oxygen
and a regular means of disposing of waste (eg, carbon
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dioxide). The body provides for these requirements
through respiration.
Factors that may affect pulmonary ventilation include
airway obstruction, swelling from infection or allergic
reaction, bronchoconstriction, medications that may
depress the central nervous system leading to a lower
respiratory rate and tidal volume, trauma, and muscular
dystrophy.
External factors that may affect respiration include the
atmospheric pressure and the partial pressure of oxygen
in the ambient air. Internal factors include pneumonia,
pulmonary edema, COPD/emphysema, hypoxia, hypoglycemia, and infection.
Adequate breathing for an adult is equivalent to a rate
of 12 to 20 breaths/min and includes a regular pattern
of inhalation and exhalation, adequate depth, bilaterally clear and equal lung sounds, and regular and equal
chest rise and fall.
Inadequate breathing for an adult is defined as fewer
than 12 breaths/min or more than 20 breaths/min and
includes shallow depth (reduced tidal volume), an irregular pattern of inhalation and exhalation, and breath
sounds that are diminished, absent, or noisy.
Even though a patient may be ventilating appropriately,
the process of respiration may be compromised. In such
a case, the EMT must assess the patient’s skin color and
mental status, and monitor oxygen levels using a pulse
oximeter.
Patients with inadequate breathing must be treated
immediately. Emergency medical care includes airway
management, supplemental oxygen, and ventilatory
support.
Oxygen-delivery devices include nonrebreathing masks,
nasal cannulas, partial rebreathing masks, Venturi
masks, tracheostomy masks, and humidified oxygen.
A patient exhibiting signs of severe respiratory distress
or respiratory failure requires assisted ventilation via a
bag-mask device or CPAP.
Artificial ventilation devices include the pocket face
mask for performing mouth-to-mask ventilations, the
bag-mask device, the manually triggered ventilation
device, and the automatic transport ventilator.
An EMT should know the difference between normal
ventilation and artificial ventilation. During normal ventilation, the diaphragm essentially sucks air into the
chest from the trachea in an attempt to equalize the
pressure in the chest with the atmospheric pressure.
Positive-pressure ventilation is generated by a device,
such as a bag-mask device, that forces air into the chest
cavity from the external environment, rather than based
on pressure changes.
The use of cricoid pressure (Sellick maneuver) during
artificial ventilations is no longer recommended.
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PREP kit
Case Study
You arrive at a local nursing home, where you find an
84-year-old woman in respiratory distress. The nursing
staff placed the patient on 4 L/min of oxygen via nasal cannula prior to your arrival. The nursing staff tells you that
the patient has been complaining of trouble breathing over
the past few days, with the difficulty becoming worse at
night. They report that the patient has been sleeping in a
recliner chair for the past two nights instead of a bed. As
you begin your examination, you notice the patient is having
obvious respiratory distress and appears to be responsive
to verbal stimuli. You contact the dispatcher to confirm an
Advanced Life Support (ALS) unit is responding. Just then,
the patient appears to become completely unresponsive and
stops breathing.
1. Which signs would suggest a patient has inadequate
ventilations?
3.As this patient is now unresponsive and possibly not
breathing, positive-pressure ventilation will likely be
required. What are some of the pitfalls associated with
positive-pressure ventilation?
4.Explain how the Venturi mask works and how its use
can benefit patients.
5.What are some conditions that may produce an inac-
curate pulse oximetry reading?
2.Compare and contrast the differences between oxygen-
ation, respiration, and ventilation.
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