When to apply Continuous Positive Airway Pressure (CPAP) in a prehospital setting to a patient with cardiogenic acute pulmonary edema (APO)?

CPAP Application in Prehospital Management of Cardiogenic Acute Pulmonary Edema

CPAP should be applied early in patients with cardiogenic acute pulmonary edema (APO) who present with respiratory distress (respiratory rate >25 breaths/min, SpO2 <90%) in the prehospital setting. 1

Initial Assessment Criteria for CPAP Application

• Apply CPAP when patients with suspected cardiogenic pulmonary edema present with:
  • Respiratory distress with respiratory rate >25 breaths/min 1
  • Oxygen saturation (SpO2) <90% despite conventional oxygen therapy 1
  • Clinical signs of increased work of breathing (use of accessory muscles, labored breathing) 2, 3
  • Bilateral crackles on auscultation 4, 2

Contraindications and Cautions

• Do not apply CPAP in patients with:
  • Hypotension (systolic blood pressure <90 mmHg) 1, 4
  • Altered mental status or risk of airway compromise 4, 5
  • Recent facial, esophageal, or gastric surgery 5
  • Inability to cooperate with the therapy 2
  • Vomiting or excessive secretions 5

Implementation Protocol

• Position patient in semi-upright position to optimize ventilation 6
• Start with initial CPAP settings:
  • Begin with 5-7.5 cmH2O of PEEP 7
  • Titrate up to 10 cmH2O based on clinical response 7
  • Entrain oxygen to maintain SpO2 94-98% 1, 6
• Monitor patient response continuously:
  • Respiratory rate (should decrease from baseline) 2, 3
  • Oxygen saturation (should improve) 8, 2
  • Blood pressure (watch for hypotension) 1, 2
  • Heart rate (should decrease with improvement) 2

Expected Benefits

• CPAP in the prehospital setting has been shown to:
  • Decrease the need for endotracheal intubation (RR 0.31,95% CI 0.17-0.55) 1
  • Improve oxygenation rapidly (typical SpO2 improvement from ~80% to >95%) 8, 2
  • Reduce respiratory rate (typically from >30 to <25 breaths/min) 2, 3
  • Potentially decrease mortality 1, 3

Duration and Continuation

• Continue CPAP throughout transport to the hospital 3
• Maintain CPAP therapy until clinical improvement is observed or until hospital arrival 3
• Coordinate with receiving emergency department regarding continuation of therapy 1

Concurrent Treatments

• While applying CPAP, continue standard medical therapy for APO:
  • Nitroglycerin (sublingual or IV) if blood pressure allows 6
  • Diuretics (IV furosemide) 6
  • Consider morphine 3-5 mg IV to reduce anxiety and improve dyspnoea 6

Special Considerations

• Ensure adequate training of prehospital personnel in CPAP application 1
• Different CPAP delivery systems (mask vs. helmet) may be used based on availability and patient tolerance 8
• Monitor for potential complications:
  • Mask discomfort or claustrophobia 5
  • Facial skin breakdown with prolonged use 5
  • Hypotension due to increased intrathoracic pressure 1, 2

When to Consider Intubation

• Despite CPAP therapy, consider intubation if:
  • Persistent hypoxemia (PaO2 <60 mmHg) despite CPAP 1
  • Hypercapnia (PaCO2 >50 mmHg) with acidosis (pH <7.35) 1
  • Deteriorating mental status or inability to protect airway 1, 4
  • Hemodynamic instability despite appropriate interventions 1

By following this algorithm, prehospital providers can appropriately identify candidates for CPAP therapy in cardiogenic APO, potentially reducing the need for intubation and improving patient outcomes.