Download 12.1 Chapter 27 Pulmonary Function

Alterations of Pulmonary
Function
Chapter 27
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Signs and Symptoms of
Pulmonary Disease
Dyspnea
 Dyspnea is the subjective sensation of
uncomfortable breathing, including
breathlessness and increased respiratory
effort.
 Causes - disturbances of ventilation, gas
exchange, or ventilation-perfusion
relationships, increased work of breathing
or any disease that damages lung tissue
(lung parenchyma).
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Signs and Symptoms of
Pulmonary Disease
Dyspnea

Pathophysiology
 May be due to a mismatch between sensory and
motor input from the respiratory center such that
there is more urge to breathe than there is
response by the respiratory muscles.
 Other causes include stimulation of central and
peripheral chemoreceptors, and stimulation of
afferent receptors in the lung and chest wall.
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Signs and Symptoms of
Pulmonary Disease
Dyspnea
 Orthopnea - dyspnea when a person is lying
down.
 Paroxysmal nocturnal dyspnea (PND) – occurs
at night, patients wake up gasping for air and
have to sit up or stand to relieve the dyspnea.
 Often
occurs with pulmonary or cardiac disease
with heart failure.
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Signs and Symptoms of
Pulmonary Disease
Abnormal breathing patterns
 Kussmaul respirations (hyperpnea) characterized by a slightly increased
ventilatory rate, very large tidal volumes, and
no expiratory pause.
 Occur
during strenuous exercise or metabolic
acidosis.
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Signs and Symptoms of
Pulmonary Disease
Abnormal breathing patterns
 Cheyne-Stokes respirations - characterized
by alternating periods of rapid, deep
breathing and shallow breathing or apnea.
 Result
from any condition that slows the blood
flow to the brain stem, which in turn slows
impulses sending information to the
respiratory centers; or from neurologic
impairment above the brain stem.
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Signs and Symptoms of
Pulmonary Disease
Hypoventilation/hyperventilation
 Background – ventilation is measured as the
minute ventilation rate.
 Minute
ventilation rate = tidal volume x
ventilation rate (in breaths per minute).
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Signs and Symptoms of
Pulmonary Disease
Hypoventilation – inadequate alveolar
ventilation in relation to metabolic demands.
 Causes - airway obstruction, chest wall
restriction, or altered neurologic control of
breathing.
 Pathophysiology - CO2 removal does not
keep up with CO2 production and the level of
CO2 in the arterial blood (PaCO2) increases.


Hypercapnia - PaCO2 more than 44mm Hg
Results in respiratory acidosis.
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Signs and Symptoms of
Pulmonary Disease
Hyperventilation - alveolar ventilation
exceeding metabolic demands.
 Causes - severe anxiety, acute head injury,
pain, and in response to conditions that
cause insufficient oxygenation of the blood.
 Pathophysiology - the lungs remove CO2
faster than it is produced by cellular
metabolism, resulting in decreased PaCO2.


Hypocapnia - PaCO2 less than 36mm Hg
Results in a respiratory alkalosis.
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Signs and Symptoms of
Pulmonary Disease
Cyanosis
 Bluish discoloration of the skin and mucous
membranes caused by increasing amounts of
deoxygenated hemoglobin.
 Causes - decreased arterial oxygenation (low
PaO2), pulmonary or cardiac right-to-left
shunts, decreased cardiac output, cold
environment, or anxiety.
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Signs and Symptoms of
Pulmonary Disease
Cyanosis
 Central cyanosis - decreased oxygen
saturation of hemoglobin in arterial blood;
best seen in buccal mucous membranes and
lips.
 Peripheral cyanosis - slow blood circulation in
fingers and toes; best seen in nail beds.
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ACTIVITY
1. A symptom of brain stem impairment is:
a. Kussmaul respirations
b. Cheyne-Stokes
respirations
2. A symptom of metabolic acidosis is:
a. Kussmaul respirations
b. Cheyne-Stokes
respirations
3. An increase in PaCO2 could be due to:
a. hyperventilation
b. hypoventilation
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Signs and Symptoms of
Pulmonary Disease
Clubbing
 Selective bulbous enlargement of the end of
a finger or toe.
 Associated with diseases that cause chronic
hypoxemia, such as lung cancer,
bronchiectasis, cystic fibrosis, pulmonary
fibrosis, lung abscess, and congenital heart
disease.
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Clubbing
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Clubbing
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Signs and Symptoms of
Pulmonary Disease
Cough
 Protective reflex that expels secretions and
irritants from the lower airways.
 Caused by stimulation of irritant receptors,
which are located in the upper airways and
proximal bronchi (few in the distal bronchi
and alveoli).
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Signs and Symptoms of
Pulmonary Disease
Cough
 Acute cough - resolves within 2 to 3 weeks of
the onset of illness or resolves with treatment.
 Usually
the result of upper respiratory
infections, allergic rhinitis, acute bronchitis,
pneumonia, congestive heart failure,
pulmonary embolus, or aspiration.
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Signs and Symptoms of
Pulmonary Disease
Cough
 Chronic cough - cough that has persisted for
more than 3 weeks.
nonsmokers – results from postnasal
drainage syndrome, asthma, or
gastroesophageal reflux disease.
 In smokers – usually due to chronic bronchitis,
and less commonly lung cancer.
 In
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Signs and Symptoms of
Pulmonary Disease
Hemoptysis
 Expectoration of bloody mucus
 Causes - bronchitis, tuberculosis, abscess,
neoplasms, and other conditions that cause
hemorrhage from damaged pulmonary
vessels.
Pain
 Chest pain can result from inflamed pleurae,
trachea, bronchi, or respiratory muscles.
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Conditions Caused by
Pulmonary Disease or Injury
Hypercapnia
 Increased PaCO2 caused by hypoventilation.
 Causes – any disorder that decreases the drive
to breathe or results in an inadequate ability to
respond to ventilatory stimulation, including drugs
that depress the respiratory center, CNS
disorders like damage to the medulla or spinal
cord, disorders of the muscles of ventilation,
thoracic deformities, airway obstruction, or
advanced emphysema.
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Conditions Caused by
Pulmonary Disease or Injury
Hypoxemia



Reduced oxygenation of arterial blood (reduced
PaO2) caused by respiratory alterations.
General causes – (a) decreased oxygen content
of inspired gas, (b) hypoventilation, (c) diffusion
abnormality, (d) ventilation-perfusion mismatch,
or (e) blood bypassing the lungs.
Diffusion of oxygen from the alveoli into the blood
depends on the V/Q ratio and the status of the
respiratory membrane.
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Conditions Caused by
Pulmonary Disease or Injury
Ventilation-perfusion (V/Q) abnormalities
 V/Q ratio - the balance between the amount
of air getting into alveoli (V) and the amount
of blood perfusing the capillaries around the
alveoli (Q).
 An
abnormal V/Q ratio is the most common
cause of hypoxemia.
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Ventilation-Perfusion
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Conditions Caused by
Pulmonary Disease or Injury
Ventilation-perfusion (V/Q) abnormalities
 Low V/Q (Shunting) - inadequate ventilation
of well-perfused areas of the lung.
 Causes
decreased systemic PaO2 and
hypoxemia.
 Occurs in atelectasis, emphysema, in asthma
as a result of bronchoconstriction, and in
pulmonary edema and pneumonia when
alveoli are filled with fluid.
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Conditions Caused by
Pulmonary Disease or Injury
Ventilation-perfusion (V/Q) abnormalities
 High V/Q - Hypoxemia also can be caused by
poor perfusion of well-ventilated portions of
the lung, resulting in wasted ventilation.
 Alveolar
dead space - an area where alveoli
are ventilated but not perfused.
 Usually due to a pulmonary embolus that
impairs blood flow to a segment of lung.
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Ventilation-Perfusion
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Conditions Caused by
Pulmonary Disease or Injury
Respiratory membrane impairment



Respiratory membrane (alveolocapillary barrier) –
composed of the epithelial lining of the alveolus, its
basement membrane, and the epithelium of the
neighboring capillary.
Diffusion of oxygen is impaired by:
 Thickening of respiratory membrane - edema & fibrosis
 Reduction in alveolar surface area - emphysema
(causes destruction of alveoli)
Hypercapnia is seldom produced because CO2 diffuses
easily across membrane.
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Conditions Caused by
Pulmonary Disease or Injury
Hypoxemia
 Circulatory bypass of lungs
 Due
to intracardiac defects that cause right-toleft shunting or because of intrapulmonary
arteriovenous malformations.

Symptoms of hypoxemia - cyanosis,
confusion, tachycardia, edema, and
decreased renal output, and compensatory
hyperventilation.
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ACTIVITY
O = causes only hypoxemia
B = causes both hypoxemia and hypercapnia
1. Pulmonary edema
2. Circulatory bypass of lungs
3. Airway obstruction
4. Breathing air with a low oxygen
content
5. Drug overdose
6. Thickening of respiratory membrane
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Conditions Caused by
Pulmonary Disease or Injury
Acute respiratory failure
 Respiratory failure is defined as inadequate
gas exchange such that PaO2 ≤50mm Hg or
PaCO2 ≥50mm Hg with pH ≤7.25.
 Can result from direct injury to the lungs,
airways, or chest wall or indirectly because of
injury to another body system, such as the
brain or spinal cord.
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Conditions Caused by
Pulmonary Disease or Injury
Acute respiratory failure
 Hypercapnic failure - result of inadequate
alveolar ventilation; requires ventilatory
support.
 Hypoxemic failure - result of inadequate
exchange of oxygen between the alveoli and
the capillaries; requires supplemental oxygen
therapy.

Often a combined hypercapnic and hypoxemic
respiratory failure occurs.
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Conditions Caused by
Pulmonary Disease or Injury
Acute respiratory failure
 Potential complication of any major surgical
procedure, especially those that involve the
central nervous system, thorax, or upper
abdomen.
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Conditions Caused by
Pulmonary Disease or Injury
Pulmonary edema
 Excess water in the lungs.
 Causes - disturbances of capillary hydrostatic
pressure, capillary oncotic pressure, or
capillary permeability. Commonly results
from:
 Left
heart failure - increases the hydrostatic
pressure in the pulmonary circulation.
 Systemic infection - increases capillary
permeability due to inflammatory cytokines.
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Pulmonary Edema
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Conditions Caused by
Pulmonary Disease or Injury
Pulmonary edema
 Clinical manifestations - dyspnea, hypoxemia,
and increased work of breathing; inspiratory
crackles (rales) and dullness to percussion
over the lung bases. In severe edema, pink
frothy sputum is expectorated and PaCO2
increases.
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Conditions Caused by
Pulmonary Disease or Injury
Aspiration
 Passage of fluid and solid particles into the
lungs.
 Tends to occur in people whose normal
swallowing mechanism and cough reflex
are impaired.
 Aspiration of large food particles or foreign
bodies can obstruct a bronchus, resulting
in bronchial inflammation and collapse of
airways distal to the obstruction.
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Conditions Caused by
Pulmonary Disease or Injury
Aspiration
 Aspiration of acidic gastric fluid may cause
severe pneumonitis (lung inflammation)
which could progress to pneumonia.
 Clinical manifestations - sudden onset of
choking, cough, vomiting, dyspnea, and
wheezing.
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Conditions Caused by
Pulmonary Disease or Injury
Atelectasis
 Collapse of lung tissue.
 Compression atelectasis - caused by
external pressure exerted by tumor, fluid,
or air in pleural space or by abdominal
distention pressing on a portion of lung,
causing alveoli to collapse.
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Conditions Caused by
Pulmonary Disease or Injury
Atelectasis
 Absorption atelectasis - results from
removal of air from obstructed or
hypoventilated alveoli or from inhalation of
concentrated oxygen or anesthetic agents.
 Clinical manifestations - include dyspnea,
cough, fever, and leukocytosis.
 Atelectasis tends to occur after surgery.
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Absorption Atelectasis
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Conditions Caused by
Pulmonary Disease or Injury
Pleural Abnormalities
Pneumothorax - accumulation of air or gas in
the pleural space.


Caused by a spontaneous rupture of weakened
areas of a pleura, or it can be secondary to pleural
damage caused by disease, trauma, or
mechanical ventilation.
Open pneumothorax - air is drawn in and out of
pleural cavity through the rupture during
breathing, so the lung will only partially inflate.
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Pneumothorax
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Conditions Caused by
Pulmonary Disease or Injury
Pleural Abnormalities
 Tension pneumothorax – the site of pleural
rupture acts as a one-way valve, permitting air
to enter on inspiration but preventing its
escape by closing up during expiration, so
pressure builds up in the pleural space.


Air pressure in the pleural space pushes against
the lung, causing compression atelectasis, and
against the mediastinum, compressing and
displacing the heart and great vessels.
Life threatening medical emergency.
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Conditions Caused by
Pulmonary Disease or Injury
Pleural Abnormalities
Pleural effusion
 Presence of fluid in the pleural space.
 Results from migration of fluids and other
blood components through the walls of intact
capillaries bordering the pleura or from
blockage or injury that causes lymphatic
vessels to drain into the pleural space.
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Pleural Effusion
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Conditions Caused by
Pulmonary Disease or Injury
Pleural Abnormalities
Pleural effusion
 Transudative effusion – watery fluid.
 Exudative effusion – contains high
concentration of white blood cells and plasma
proteins.
 Hemothorax – blood in pleural space.
 Chylothorax – chlye in pleural space.
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Conditions Caused by
Pulmonary Disease or Injury
Pleural Abnormalities
Pleural effusion
 Empyema (infected pleural effusion) – fluid
contaminated with pus from an infection.
 Develops
when pulmonary lymphatics become
blocked, leading to an outpouring of
contaminated lymphatic fluid into the pleural
space.
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Conditions Caused by
Pulmonary Disease or Injury
Pleural Abnormalities
Pleurisy (pleuritis)
 Inflammation of the pleura.
 Usually results from an infection of the
adjacent lung tissue, but could be caused by
thoracic trauma or an invading tumor.
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Pulmonary Disorders
Restrictive Lung Diseases
 Characterized by decreased compliance of
lung tissue and resultant increased work of
breathing.
 Commonly affect the alveolocapillary
membrane and cause decreased diffusion
of oxygen from the alveoli into the blood
resulting in hypoxemia.
 Includes pulmonary edema, atelectasis
and pneumothorax, as well as the
following.
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Restrictive Lung Diseases
Pulmonary fibrosis
 Excessive amount of fibrous or connective
tissue in the lung, which diminishes lung
compliance and diffusing capacity of
alveolocapillary membrane.
 May be idiopathic or caused by diseases such
as infections, ARDS, autoimmune disorders or
inhalation of harmful substances.
 Diffuse pulmonary fibrosis has a poor
prognosis.
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Pulmonary Fibrosis
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Restrictive Lung Diseases
Pneumoconiosis
 Any change in the lung caused by
inhalation of inorganic dust particles.
 Often occurs after years of exposure to the
offending dust, with progressive fibrosis of
lung tissue.
 Causes – most commonly from inhalation
of silica, asbestos, and coal (others are
less common).
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Restrictive Lung Diseases
Pneumoconiosis

Pathophysiology – deposition of these
materials in the lungs leads to chronic
inflammation with scarring of the alveolocapillary membrane leading to pulmonary
fibrosis.


Dust deposits are permanent and lead to
progressive pulmonary deterioration.
Clinical manifestations - cough, chronic
sputum production, dyspnea, decreased lung
volumes, and hypoxemia.
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Restrictive Lung Diseases
Acute respiratory distress syndrome (ARDS)


A fulminant form of respiratory failure that results
from acute lung inflammation, diffuse injury to
the alveolocapillary membrane, and hyaline
membrane formation in the alveoli.
Often occurs as a complication of sepsis and
multiple trauma; but also with many other
disorders including pneumonia, burns,
aspiration, pancreatitis, inhalation of smoke or
noxious gases, oxygen toxicity and disseminated
intravascular coagulation.
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Restrictive Lung Diseases
Acute respiratory distress syndrome (ARDS)
 Pathophysiology:



An insult to the body damages the
alveolocapillary membrane, resulting in the
systemic release of high levels of inflammatory
cytokines (especially TNF-alpha and IL-1).
Inflammation causes breakdown of the alveolarcapillary barrier, thus flooding the alveoli with
protein-rich exudate and cells, causing edema
and development of a hyaline membrane.
Hyaline membrane - thick, gel-like layer that
forms when protein deposits in the alveoli.
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Acute Respiratory Distress
Syndrome (ARDS)
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Restrictive Lung Diseases
Acute respiratory distress syndrome (ARDS)
 Pathophysiology (cont.):

Inflammation is complicated by loss of surfactant,
causing atelectasis, and by vasoconstriction of the
alveolar capillaries and pulmonary thrombus
formation.
 The resultant V/Q mismatch is usually very severe,
and the associated hypoxemia is not responsive to
administration of supplemental oxygen.
 As the lungs become stiffer (decreasing lung
compliance) due to fluid and atelectasis,
hypoventilation and hypercapnia follow.
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ARDS
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Restrictive Lung Diseases
Acute respiratory distress syndrome (ARDS)
 Clinical manifestations - dyspnea; rapid,
shallow breathing; inspiratory crackles;
respiratory alkalosis; decreased lung
compliance; hypoxemia unresponsive to
oxygen therapy (refractory hypoxemia); and
diffuse alveolar infiltrates on radiographs,
without evidence of cardiac disease.
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Restrictive Lung Diseases
Acute respiratory distress syndrome (ARDS)
 Patients frequently present with the symptoms
of the original insult, followed in 24 to 48 hours
by increasing dyspnea. This may progress to
complete respiratory failure and death.
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ACTIVITY
Why is ARDS considered a restrictive lung
disease rather than obstructive?
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Obstructive Lung Diseases
Obstructive Lung Diseases
 Characterized by airway obstruction that is
worse with expiration.
 During
inspiration airways stretch to allow
air in.
 During expiration excess mucus or loss of
lung elasticity causes airways to collapse,
trapping air in the alveoli.
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Obstructive Lung Diseases
Obstructive Lung Diseases



Patients exhibit dyspnea, and wheezing that is
worse with expiration, with increased work of
breathing, V/Q mismatching, and a decreased
forced expiratory volume in one second (FEV1).
Trapping of air in alveoli can cause less CO2 to
be exhaled, resulting in hypercapnia.
The major obstructive lung diseases are asthma,
chronic bronchitis, and emphysema.
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Obstructive Pulmonary Disease
Normal
Emphysema
Chronic
bronchitis
Asthma
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Obstructive Lung Diseases
Asthma
 Asthma is a chronic inflammatory disorder of
the airways.
 Results from a type 1 hypersensitivity immune
response involving the activity of lymphocytes,
IgE, mast cells, and eosinophils.
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Obstructive Lung Diseases



Asthma: an animation
http://www.youtube.com/watch?v=7EDo9pUYv
PE
Advance to 1:00.
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Obstructive Lung Diseases
Asthma
 Occurs in individuals with a genetic
predisposition to certain environmental
antigens (allergens) so that high levels of
interleukin-4 (IL-4) and IgE are produced.
 This causes the airways to be
hyperresponsive to allergens, with excessive
mast cell degranulation, and resulting mucus
secretion, bronchoconstriction, and
pulmonary edema.
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Asthma
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Asthma
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Obstructive Lung Diseases
Asthma
 Clinical manifestations during attacks - tripod
positioning, use of accessory muscles,
tachypnea, tachycardia, expiratory
wheezing/prolonged expiratory phase,
increased pulsus paradoxus (a decrease in
systolic blood pressure during inspiration of
more than 10mm Hg).
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Tripod Positioning
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Obstructive Lung Diseases
Asthma
 Status asthmaticus - acute exacerbation of
asthma that does not respond to standard
treatments of bronchodilators and steroids.
The resulting hypoxemia and respiratory
acidosis can be life-threatening if not
reversed rapidly.
 Asthma staging is based on clinical severity
from mild intermittent to severe persistent
and is used to determine therapy.
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Chronic Obstructive
Pulmonary Disease



Syndrome that includes emphysema and
chronic bronchitis.
Characterized by airflow limitation that is
not fully reversible, is usually progressive,
and is associated with an abnormal
inflammatory response of the lung to
noxious particles or gases.
Primarily caused by cigarette smoke,
though genetic susceptibilities also have
been identified.
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Chronic Obstructive
Pulmonary Disease


How chronic obstructive pulmonary
disease develops
http://www.youtube.com/watch?v=2wF1cs
ksp-Q&feature=related
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Chronic Obstructive
Pulmonary Disease
Chronic bronchitis
 Hypersecretion of mucus and chronic
productive cough that lasts for at least 3
months of the year and for at least 2
consecutive years.
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Chronic Bronchitis
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Chronic Obstructive
Pulmonary Disease
Chronic bronchitis
 Pathophysiology:
 Inhalation
of irritants causes inflammation
and hyperplasia of the mucus-producing
goblet cells of the bronchial epithelium and
hypertrophy of smooth muscle.
 Accumulated mucus facilitates growth of
bacteria, which further contributes to airway
inflammation, bronchospasm, and eventual
scarring.
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Chronic Obstructive
Pulmonary Disease
Chronic bronchitis
 Pathophysiology:
 Narrowed
airways cause V/Q mismatching
and expiratory airway obstruction with air
trapping, resulting in hypoxemia and
hypercapnia.
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Chronic Obstructive
Pulmonary Disease
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Chronic Obstructive
Pulmonary Disease
Chronic bronchitis
 Accumulations of thick mucus make
patient at risk for recurrent pulmonary
infections.
 Clinical manifestations - productive cough
of purulent sputum (earliest symptom),
dyspnea, prolonged expiratory phase,
wheezing, cyanosis, and edema.
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Chronic Obstructive
Pulmonary Disease
Chronic bronchitis
 Treatment – bronchodilators,
expectorants, and chest physical therapy;
during acute attacks antibiotics, steroids
and mechanical ventilation may be
required.
 If
patient stops smoking, progression can
be halted.

Prevention through smoking cessation is
best option since damage is irreversible.
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Chronic Obstructive
Pulmonary Disease
Emphysema
 Abnormal permanent enlargement of the
gas-exchange airways accompanied by
destruction of alveolar walls without
obvious fibrosis.
 Airflow
limitation occurs due to loss of
elastic recoil.

Major cause is cigarette smoking.
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Emphysema
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Chronic Obstructive
Pulmonary Disease
Emphysema
 Primary emphysema (1-3% of cases) is
linked to an inherited deficiency of the
enzyme alpha 1-antitrypsin, which
normally inhibits the action of many
proteolytic enzymes in the lungs.
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Chronic Obstructive
Pulmonary Disease
Emphysema
 Pathophysiology:
 Inhaled
irritants cause an imbalance between
lung proteases (that break down lung tissue,
like elastin) and antiproteases (that preserve
lung tissue, like alpha 1-antitrypsin) so that the
alveoli and bronchial walls are destroyed.
 Alveolar destruction causes decreased
surface area for gas exchange, leading to
hypoxemia.
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Chronic Obstructive
Pulmonary Disease
Emphysema
 Pathophysiology:
 Bronchial
wall damage causes loss of
elastic recoil, leading to expiratory airway
collapse, air trapping, hypoventilation, and
hypercapnia.
 Air trapping causes hyperinflation of lungs
and increased residual lung volume, with
much energy expended on breathing, and
eventually increased thoracic diameter.
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Chronic Obstructive
Pulmonary Disease
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Emphysema
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Emphysema
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Chronic Obstructive
Pulmonary Disease
Emphysema
 Clinical manifestations – severe dyspnea,
nonproductive cough, weight loss, barrel
chest, prolonged expiratory phase, and
wheezing.
 Treatment - smoking cessation,
bronchodilators, nutrition, breathing
retraining, relaxation exercises, antiinflammatory medications, and antibiotics
for acute infections.
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Obstructive Pulmonary Disease
Normal
Emphysema
Chronic
bronchitis
Asthma
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ACTIVITY
a. Asthma b. Chronic bronchitis c. Emphysema
1. Involves a hypersensitivity reaction.
2. Involves destruction of alveolar septa.
3. Involves hyperplasia and hypertrophy
of cells in airways.
4. Productive cough
5. Barrel chest
6. Systemic edema
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Respiratory Tract Infections
Pneumonia
 Acute infection of the lung that is caused by
bacteria, viruses, fungi, or parasites.
 Risk factors - anything that compromises
normal respiratory defense mechanisms,
such as age, smoking, compromised immune
system, malnutrition, mechanical ventilation,
and immobilization.
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Respiratory Tract Infections
Categories of Pneumonia



Community Acquired Pneumonia (CAP)–most
commonly caused by viruses (e.g., influenza) or
by bacteria (e.g., Streptococcus pneumoniae,
Mycoplasma pneumoniae).
Nosocomial– acquired in hospital, often due to a
dangerous organism that is difficult to treat (e.g.,
Pseudomonas aeruginosa).
Immunocompromised Individuals– often due
to opportunistic infections by the fungus
Pneumoncystis jiroveci (P. carinii) or by the
cytomegalovirus.
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Respiratory Tract Infections
Pneumonia
 Pathophysiology:
 Organisms
enter the respiratory tract, often by
aspiration of infected oral secretions.
 These organisms overwhelm the alveolar
macrophages and set off an intense
immunologic and inflammatory response.
 Inflammatory cytokines, white blood cells, and
edema fluid flood the alveoli and bronchi.
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Respiratory Tract Infections
Pneumonia
 Pathophysiology:
 Exudates
and fibrin are deposited in alveoli
and interfere with gas exchange.
 Ventilation/perfusion (V/Q) mismatching
occurs with resultant hypoxemia.
 The infection may spread to the bloodstream
(bacteremia and sepsis), pleura (empyema),
or other organs (e.g., meningitis).
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Pneumococcal Pneumonia
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Respiratory Tract Infections
Pneumonia
 Clinical manifestations- fever, usually a
productive cough, and dyspnea; infiltrates on
chest X-ray; leukocytosis.
 Treatment – antibiotics for bacterial
pneumonia; supportive care for viral
pneumonia.
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Respiratory Tract Infections
Tuberculosis
 An infection caused by Mycobacterium
tuberculosis that usually affects the lungs but
may invade other body systems.
 In the U.S. most active cases are in AIDS
patients and other immunocompromised
individuals.
 Transmitted from person to person in
airborne droplets.
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Respiratory Tract Infections
Tuberculosis
 Pathophysiology:
 Microorganisms
lodge in the lung periphery,
usually in the upper lobe.
 Bacilli multiply and cause nonspecific
pneumonitis (lung inflammation).
 Bacilli are engulfed by macrophages and
neutrophils which seal off the colonies of
bacilli to prevent spread, forming a
granulomatous lesion called a tubercle.
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Tuberculosis
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Respiratory Tract Infections
Tuberculosis
 Pathophysiology:
 Once
the bacilli are isolated in tubercles and
immunity develops, tuberculosis may remain
dormant for life.
 If the immune system is impaired, or if live
bacilli escape into the bronchi, active disease
occurs and may spread through the blood and
lymphatics to other organs.
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Respiratory Tract Infections
Tuberculosis
 Clinical Manifestations
 Latent
tuberculosis is asymptomatic.
 Active tuberculosis - fever, night sweats,
dyspnea, productive cough (sometimes with
hemoptysis, i.e. blood in sputum), and weight
loss.
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Respiratory Tract Infections
Tuberculosis
 Usually diagnosed by a positive tuberculin
skin test (PPD), sputum culture, and chest
radiographs.
 Treatment - antibiotic therapy (6- to 9-month
course of treatment)
 Multidrug resistant strains of TB are arising
which are very difficult to control.
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Respiratory Tract Infections
Severe Acute Respiratory Syndrome (SARS)
 A severe pneumonia that affected more
than 300 people in China in 2002- 2003
and spread rapidly around the world.
 Caused by a strain of coronavirus.
 Fatality rate was 4% to 6%.
 Spread mainly by inhalation of droplet
nuclei, or by contact with infected
respiratory excretions.
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Respiratory Tract Infections
Severe Acute Respiratory Syndrome (SARS)
 Clinical manifestations - high fever, body
aches, dry cough, and dyspnea.
 Treatment - mainly supportive, although
several antivirals are being tested.
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Pulmonary Vascular Disease
Pulmonary embolism
 Occlusion of a portion of the pulmonary
vascular bed by a thrombus, embolus,
tissue fragment, lipids, or an air bubble.
 Pulmonary emboli most commonly arise
from the deep veins in the legs or pelvis.
 Thromboembolism – specifically due to a
portion of a clot that has broken off into the
bloodstream.
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Pulmonary Vascular Disease
Pulmonary embolism (cont.)
 Risk factors – anything that promotes
blood clotting, immobility, trauma and
fractures of the head, spine, legs and
pelvis; incidence increases with age.
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Pulmonary Embolism
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Pulmonary Vascular Disease
Pulmonary embolism
 Pathophysiology:




An embolus, often from a deep leg vein, breaks off
and travels through the venous circulation.
It travels through the right heart and lodges in the
pulmonary arterial circulation, blocking flow into the
affected portion of the lungs.
This causes immediate V/Q mismatch, hypoxemia,
and pulmonary hypertension.
Hypoxemia interferes with surfactant production,
resulting in collapse of alveoli.
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Pulmonary Vascular Disease
Pulmonary embolism
 Pathophysiology:



Small emboli often do not cause lung
infarction.
Larger emboli often cause some infarction of
lung tissue with associated hypoxic
vasoconstriction, atelectasis, and loss of
functional lung tissue.
Very large emboli cause massive occlusion,
resulting in cardiogenic shock and death.
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Pulmonary Vascular Disease
Pulmonary embolism
 Initial symptoms are typically sudden onset
of dyspnea, pleuritic chest pain and
hemoptysis.
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Pulmonary Embolism
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Pulmonary Vascular Disease
Pulmonary hypertension
 Mean pulmonary artery pressure 5 to 10
mm Hg above normal or above 20 mm Hg.
 Primary pulmonary hypertension - rare
idiopathic disorder involving the
precapillary pulmonary arteries; due to
hereditary factors in some cases.

Decreased endogenous vasodilators,
increased vasoconstrictors, and vascular
remodeling combine to cause vasoconstriction
and fibrotic changes in the vessel walls.
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Pulmonary Vascular Disease
Pulmonary hypertension
 Secondary pulmonary hypertension results from diseases of the respiratory
system that cause hypoxemia and are
characterized by pulmonary arteriolar
vasoconstriction and arterial remodeling.
 Most
commonly due to chronic pulmonary
disease.
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Pulmonary Vascular Disease
Pulmonary hypertension
 Pathophysiology:




Narrowing of the vessels increases resistance
to pulmonary artery inflow to the lungs.
Pulmonary artery pressures rise, creating
significant afterload to the right ventricle.
This results in right ventricular hypertrophy that
usually progresses to right heart failure, which
is called cor pulmonale.
Pressures then back up into the systemic
venous circulation.
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Pulmonary Hypertension
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Pulmonary Vascular Disease
Cor pulmonale
 Right ventricular enlargement caused by
chronic pulmonary hypertension.
 Progresses to right ventricular failure if the
pulmonary hypertension is not reversed.
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Lung Cancer




Most common cause of cancer death in
the United States.
Commonly caused by cigarette smoking.
Heavy smokers have a 20 times’ greater
chance of developing lung cancer than
nonsmokers.
Other environmental factors can also
contribute, such as asbestos and radiation
exposure.
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Lung Cancer
Bronchogenic carcinomas - primary lung
cancers arising from the bronchi. Two
major types:
 Non–small cell lung carcinoma - 75-85%
of lung cancers; different types have
different characteristics, but in general
these are slower growing and slower to
metastasize than small cell tumors.
 Small cell lung carcinoma - rarer; grow and
metastasize rapidly. Very poor prognosis.
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Lung Cancer

Lung cancers most frequently metastasize
to the brain, bone marrow, and liver.
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