Download CPAP BASICS

CPAP BASICS
GRANT
COUNT Y
APRIL 2014
OBJECTIVES
Establish a protocol for Continuous Positive
Airway Pressure usage for pre-hospital
respiratory distress
Discuss the basic principles of Continuous
Positive Airway Pressure and its application
Review the physiological effects of CPAP
Discuss the indications and contraindications
of CPAP usage
DEFINITIONS
 “Learn the Lingo”
 NIPPV: Non-Invasive Positive Airway Pressure
 Includes BiPAP, CPAP, Bag valve mask
 Continuous Positive Airway Pressure (CPAP)
 What we will be using
 Bi-Level Positive Airway Pressure (Bi-PAP)
 Often used in the hospital once the patient arrives
 PEEP: Positive End Expiratory Pressure
 A value we can measure on ventilated patients (ie,
closed circuit)
 Both BiPAP and CPAP provide a small amount of PEEP
BIPAP VS CPAP
 BiPAP
 Continuous Pressure
 Pressures are different
between inhalation and
exhalation (ie, 12/8
cm/H20)
 Not commonly used in
the field or at home due
to the complexity of
delivery/devices
 Needs monitoring of
delivered pressures
 Expensive
 CPAP
 Continuous Pressure
 Same pressure during
exhalation and
inhalation
 Used in the field and at
home
 Less complicated
devices for delivery
 Needs little monitoring
 Set it and it’s good
 Cheaper
CPAP
 Continuous positive pressure delivery system
 Provides more airway pressure than a non -rebreather
mask but less than BVM
 Similar to sticking your head out of a window while
traveling at highway speeds 
CPAP USAGE ADVANTAGES
 Non-invasive
 Easily Applied
 Easily Removed
 Useful for many types of respiratory distress
 CHF, COPD, Asthma, Pneumonia, Near drownings
 Able to give nebs and other medications “in -line” or while
it is applied
 Can serve as a “bridge” to give patients extra respiratory
support as the other medications and treatments have
time to take effect (ie. Nitro/lasix, duonebs, steroids,
etc)
 Can help avoid intubations for patients that are likely to
rapidly improve with adjunct treatments
CPAP ADVANTAGES
 “Alternative” to ETT Intubation
 Some patients are not great candidates for intubations or are frail and
likely to have a difficult extubation
 Prospective randomized trials have shown 50 -70% of patients with a
severe COPD exacerbation who receive non-invasive ventilation can avoid
intubation
 Prehospital use of CPAP for moderate-severe respiratory failure has been
proven effective
 Reduction in intubation rate of 30%
 Absolute Reduction in mortality of 21% In appropriately selected patients who
received CPAP instead of usual care (intubation)
 COPD patients who are intubated typically are ventilator dependent for
longer periods (difficult to extubate), causes increased morbidity with
pneumonia risk and risk for spontaneous pneumothorax
WHY CPAP?
 Positive Pressure!
 Redistributes lung fields (inflates)
 Reduces work of breathing
 Counteracts intrinsic PEEP
 Pursed lip breathing
 Improves Lung Compliance
 Reverses Atelectasis
 Collapsed alveoli
 Decreases Preload/Afterload
 Beneficial esp for CHF patients
 Decreased V/Q mismatch (ventilation/perfusion)
 Improves Gas Exchange
V/Q MISMATCH
 Ventilation and perfusion mismatch
 Causes:
 Pulmonary Edema
 Pneumonia
 Increased dead space (collapsed or atelectatic lung)
 Pulmonary embolism
 Shunt
NORMAL V/Q
 Upper Lungs
 V>P
 Mid Lungs
 V=P
 Lower Lungs
 V<P
 Overall Avg:80%
HIGH V/Q RATIO
 Caused by lack of perfusion (ventilation is normal)
 Pulmonary embolism
 Cardiac arrest
 Hypovolemia/shock
 Normal phenomenon in dead space
 Upper lung, V>P
LOW V/Q RATIO
 Enough Perfusion, not enough ventilation
 Atelectasis
 Increased secretions
 Mucus plugging
 Bronchial intubation
 shunt
PARTIAL PRESSURE OF GAS
 Hypothetical pressure of a gas in the atmosphere
were it to occupy the same volume of space as the
mixture it is in
 Air at sea level has a pressure of 1 atmosphere, or
760 mmHg
 Air is 21% oxygen at sea level
 The partial pressure of room air 02 is 760 x 0.21 =
159 mmHg
PRESSURE GRADIENTS
 The dif ference in pressure between a higher concentration of
gas and a lower concentration of gas is called a pressure
gradient
 Gas has a tendency to move from a higher partial pressure to a
lower partial pressure until equilibrium is established
 This pressure gradient is what causes oxygen to enter the blood
and CO2 to leave the blood (gas exchange)
 Happens at the alveolar level
 Expired air has oxygen content of about 16%, so the parital
pressure is 760 mmHg x 0.16 = 121 mmHg
 The pressure gradient of oxygen between room air (159mmHg)
and blood oxygen (121mmHg) creates a gradient to allow
oxygen exchange
CPAP AND PRESSURE GRADIENTS
 CPAP changes the pressure gradient
 CPAP is measured by cmH2O
 1 cm H2O = 0.725 mmHg
 Typically CPAP is applied at either 5 or 10 cmH2O
 This increases the partial pressure by 2.25%
 Increased partial pressure of oxygen delivered
results in greater differential and improved oxygen
exchange
 The clinical effects can be impressive with even this
small change
MECHANICAL EFFECTS
 Increased airway pressure with CPAP
 Stent open airways that are at risk of collapse due to
excess fluid or edema
 Inflates alveoli and prevents collapse during expiration
 Creates greater surface area= better exchange of gases
 Decreases the work of breathing by preventing continual
collapse of the airways
 Patient senses easier breathing, less work esp on inspiration
 Maintains gas exchange over a longer period of time
PHYSIOLOGICAL EFFECTS OF CPAP
 Increased oxygen levels
 Reduced work of breathing
 Reduced V/Q mismatch
GRANT COUNT Y PROTOCOL
 Indications: moderate to severe respiratory distress
from the following:
 Pulmonary edema/CHF (including from near drownings)
 Acute Asthma exacerbation not responding quickly to
usual treatments
 COPD exacerbation failing conventional treatments
 Pneumonia
CONTRAINDICATIONS
 DO NOT USE CPAP IF:
 The patient is unconscious or altered
 GCS<13-14 or unable to protect their own airway
 Hypotensive (SBP <90 mmHg)
 Vomiting
 Suspected pneumothorax (ensure equal bilateral breath sounds
prior to application)
 Trauma
 Facial abnormalities
 Unable to obtain mask seal (large beard, etc)
 Extreme caution in pulmonary fibrosis (lowest pressure setting
if used)
 Dementia (moderate or severe)
PROCEDURE
 Know your CPAP device and how to adjust it (many options out
there)
 Overall goal is to increase airway pressure and improve
oxygen delivery/gas exchange




Verbally coach patient, explain the procedure
Apply waveform capnography (ETCO2)
Apply CPAP with pressure of 5-10 cmH20
Coach and reassure the patient (slow, deep breaths)
 Watch for resistance and apprehension
 Check for leaks around the mask/ensure good seal
 Reassess lung sounds and vitals q3-5 minutes
PROCEDURE
 In line nebs can be administered while the CPAP is
on
 Nitroglycerin may be administered by momentarily
lifting the facemask
 If the patient becomes more confused or is not
tolerating the CPAP mask and still has severe
distress, move to ETT intubation or other advanced
airway measures
PRECAUTIONS
 CPAP may cause a drop in blood pressure due to
increased intrathoracic pressure
 Watch for GI distention, which may lead to vomiting
 Patient may become claustrophobic or unwilling to
tolerate mask
 Sometimes coaching can overcome this, give them
direct feedback on inhalation and exhalation
 Use with great caution in patients with dementia,
must have cognitive ability to understand what CPAP
does
SPECIAL NOTES
 Proceed to advanced airway for patients with
worsening respiratory distress or decreasing level of
consciousness
 Not for use in children <12 years old
 Advise receiving hospital of CPAP application so they
can prepare and have respiratory therapy on standby
IMPORTANT POINTS
 Pulmonary Edema patients often improve within
minutes of application of CPAP
 CPAP is to pulmonary edema like D50 is to
hypoglycemia
 Visual inspection if chest wall movement should
demonstrate improved respiratory excusion
 Bilateral chest wall movement, retractions, etc
 “Look, listen and feel”
CPAP VS INTUBATE
 When to do what:
 Respiratory distress = increased effort and frequency
of breathing in maintaining normal O2 and CO2 in
the blood
 Respiratory Failure = inability to maintain normal
amounts of O2 and CO2 in the blood
RESPIRATORY DISTRESS
 Signs of respiratory distress:
 Tachypnea
 Tachycardia
 Accessory muscle use
 Decreased Tidal Volume
 Paradoxical breathing (abdominal muscles)
 CPAP can generally be used on these patients
RESPIRATORY FAILURE
 Declining tidal volume
 Irregular or gasping breaths
 Poor color = poor perfusion = poor oxygen exchange
 Not likely to improve without invasive measures
 Decline in LOC
 Hypercarbia
 Hypoxemia
 High CO2 lowers pH, causing acidosis
 Acidosis causes further metabolic changes and ultimately
leads to cardiac arrest
SUMMARY
 CPAP can provide an adjunct to allow medications to
take effect (“Buys time”)
 CPAP reverses CHF induced pulmonary edema
 CPAP can prevent prolonged ventilation that can
occur after intubation
 Non-invasive = can be used on DNI
 Fixes V/Q mismatch, opens airways, increases
oxygen pressure gradient, reduces work of breathing