Continuous positive airway pressure has become an essential skill for emergency medical service providers. When a patient presents in acute respiratory distress from CHF, pulmonary edema, or COPD exacerbation, early CPAP intervention can dramatically improve outcomes. This guide walks through the setup process, patient coaching, and monitoring that make prehospital CPAP successful.
Before You Begin: Patient Assessment
CPAP isn’t appropriate for every patient in respiratory distress. Before assembling your equipment, confirm that your patient meets the criteria established in your local protocols. Generally, appropriate candidates are awake and able to follow commands, can maintain their own airway, have systolic blood pressure above 90 mmHg, are old enough and large enough to fit the available mask sizes, and present with respiratory distress consistent with CPAP-responsive conditions (CHF, pulmonary edema, COPD, asthma, pneumonia).
Patients who are vomiting, have suspected pneumothorax, cannot protect their airway, or are in respiratory arrest are not candidates for CPAP and require alternative interventions.
Equipment Assembly
Modern prehospital CPAP devices are designed for rapid deployment. While specific steps vary by manufacturer, the general process follows a similar pattern:
First, connect your CPAP generator to the oxygen source. Most EMS CPAP devices require a 50-psi oxygen source (direct tank or wall connection), not a standard flowmeter. Verify your oxygen supply is adequate—CPAP consumes oxygen quickly, and running out mid-transport creates serious problems.
Next, attach any required filters to the air entrainment port. These protect both the device and the patient from particulates.
Connect the corrugated tubing to the generator, then attach the appropriately sized mask to the tubing. Most adults require a large mask, though small adult and pediatric sizes should be available.
Finally, attach the PEEP valve or pressure selector to the mask’s exhalation port. Many disposable systems have this integrated, while others require separate valve attachment.
Setting Initial Parameters
Before applying the mask to your patient, configure your initial settings:
For pressure, start at 5 cm H₂O for patients with bronchospastic conditions (asthma, COPD) or 10 cm H₂O for patients with pulmonary edema or CHF. Your protocols may specify different starting points.
For oxygen, many systems start with a moderate concentration (around 28-30% FiO₂) with the option to increase based on pulse oximetry readings. Some protocols call for starting at high flow and titrating down.
Turn the device on and verify airflow by feeling air coming through the mask before placing it on the patient.
Patient Preparation and Coaching
This step often determines whether CPAP succeeds or fails. Patients in respiratory distress are frightened, and having a mask placed over their face can trigger panic and resistance.
Before touching the patient with the mask, explain what you’re about to do. Tell them the mask will help them breathe easier, that they’ll feel air pressure, and that they need to breathe normally and keep the mask in place. Reassure them that they can breathe against the pressure—their anxiety about this is often worse than the reality.
Position the patient upright, ideally at 90 degrees or as close as their condition and your setting allow. CPAP works best in upright patients and may be less effective or even harmful in supine positioning.
Applying the Mask
Hand the mask to the patient first, allowing them to hold it to their own face. This gives them a sense of control and lets them acclimate to the airflow before the mask is secured. Coach them through their first few breaths.
Once the patient is tolerating the airflow, apply the head straps. Secure the mask firmly enough to create a seal but not so tight that it causes discomfort or pressure injuries. You should be able to slide a finger between the straps and the patient’s skin.
Check for air leaks, particularly around the nose and cheeks. Some leakage is expected and acceptable, but large leaks reduce therapy effectiveness and may blow air into the patient’s eyes.
Monitoring During Treatment
Once CPAP is running, your job shifts to assessment and monitoring:
Watch for signs of improvement within the first five minutes: decreasing respiratory rate, decreasing heart rate, improving oxygen saturation, decreasing blood pressure (in hypertensive patients), and reduced use of accessory muscles.
Continue to coach the patient. Remind them to keep the mask in place, breathe normally, and stay calm. Patients often want to remove the mask, especially initially, and ongoing encouragement helps them push through the adjustment period.
Monitor for complications: worsening respiratory status, vomiting (remove the mask immediately), decreasing blood pressure, or patient intolerance. If the patient cannot tolerate CPAP or deteriorates, be prepared to transition to bag-valve-mask ventilation or advanced airway management.
Consider adjunct treatments your protocols allow, such as nitroglycerin for CHF (administered without breaking the mask seal if possible) or nebulized bronchodilators if your CPAP system supports inline nebulization.
Documentation
Record the time CPAP was initiated, initial settings, the patient’s response, any setting changes, and the patient’s condition on arrival at the receiving facility. Document oxygen saturation, respiratory rate, and other vital signs before and after CPAP application to demonstrate the intervention’s effect.
Troubleshooting Common Issues
If the patient’s oxygen saturation isn’t improving, check for mask leaks, increase the FiO₂, verify the device is functioning properly, and confirm CPAP is appropriate for this patient’s condition.
If the patient is fighting the mask, slow down and re-coach. Some patients need several minutes of holding the mask themselves before they’re ready for strap application. In select cases where the patient would benefit from CPAP but cannot tolerate it due to anxiety, protocols may allow for mild anxiolytics—though this requires careful consideration given the risks of respiratory depression.
If you hear gurgling or the patient develops abdominal distension, they may be swallowing air. Reposition the mask, adjust pressure if your protocols allow, and monitor closely.
Effective CPAP delivery in the field combines technical skill with patient communication. Master both, and you’ll have a powerful tool for managing some of the most challenging respiratory emergencies EMS providers face.