cpap basics
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CPAP BASICS. GRANT COUNTY 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 - PowerPoint PPT PresentationTRANSCRIPT
GRANT COUNTYAPRIL 2014CPAP BASICS
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 CPAPDiscuss the indications and
contraindications of CPAP usage
OBJECTIVES
“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
DEFINITIONS
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
BIPAP VS CPAP
Continuous positive pressure delivery systemProvides more airway pressure than a non-
rebreather mask but less than BVMSimilar to sticking your head out of a window
while traveling at highway speeds
CPAP
Non-invasiveEasily AppliedEasily RemovedUseful for many types of respiratory distress
CHF, COPD, Asthma, Pneumonia, Near drowningsAble to give nebs and other medications “in-line”
or while it is appliedCan 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 USAGE 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
CPAP ADVANTAGES
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
WHY CPAP?
Ventilation and perfusion mismatchCauses:
Pulmonary EdemaPneumonia Increased dead space (collapsed or atelectatic lung)
Pulmonary embolismShunt
V/Q MISMATCH
Upper LungsV>P
Mid LungsV=P
Lower LungsV<P
Overall Avg:80%
NORMAL V/Q
Caused by lack of perfusion (ventilation is normal)Pulmonary embolismCardiac arrestHypovolemia/shock
Normal phenomenon in dead spaceUpper lung, V>P
HIGH V/Q RATIO
Enough Perfusion, not enough ventilationAtelectasis Increased secretionsMucus pluggingBronchial intubationshunt
LOW V/Q RATIO
Hypothetical pressure of a gas in the atmosphere were it to occupy the same volume of space as the mixture it is inAir at sea level has a pressure of 1 atmosphere, or 760 mmHg
Air is 21% oxygen at sea levelThe partial pressure of room air 02 is 760 x 0.21 = 159 mmHg
PARTIAL PRESSURE OF GAS
The difference 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
PRESSURE GRADIENTS
CPAP changes the pressure gradientCPAP is measured by cmH2O
1 cm H2O = 0.725 mmHgTypically CPAP is applied at either 5 or 10
cmH2OThis 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
CPAP AND PRESSURE GRADIENTS
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
MECHANICAL EFFECTS
Increased oxygen levelsReduced work of breathingReduced V/Q mismatch
PHYSIOLOGICAL EFFECTS OF CPAP
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
GRANT COUNTY PROTOCOL
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)
CONTRAINDICATIONS
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
PROCEDURE
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 maskSometimes 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
PRECAUTIONS
Proceed to advanced airway for patients with worsening respiratory distress or decreasing level of consciousness
Not for use in children <12 years oldAdvise receiving hospital of CPAP application
so they can prepare and have respiratory therapy on standby
SPECIAL NOTES
Pulmonary Edema patients often improve within minutes of application of CPAPCPAP is to pulmonary edema like D50 is to hypoglycemia
Visual inspection if chest wall movement should demonstrate improved respiratory excusionBilateral chest wall movement, retractions, etc
“Look, listen and feel”
IMPORTANT POINTS
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
CPAP VS INTUBATE
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 DISTRESS
Declining tidal volumeIrregular or gasping breathsPoor 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
RESPIRATORY FAILURE
CPAP can provide an adjunct to allow medications to take effect (“Buys time”)
CPAP reverses CHF induced pulmonary edemaCPAP can prevent prolonged ventilation that
can occur after intubationNon-invasive = can be used on DNIFixes V/Q mismatch, opens airways, increases
oxygen pressure gradient, reduces work of breathing
SUMMARY