Should Continuous Positive Airway Pressure (CPAP) or Bi-level Positive Airway Pressure (BiPAP) be instituted for a patient with pulmonary edema?

From the Guidelines

For a patient with pulmonary edema, CPAP (Continuous Positive Airway Pressure) is generally the preferred initial non-invasive ventilation method over BiPAP (Bi-level Positive Airway Pressure). This recommendation is based on the most recent and highest quality study available, which suggests that CPAP and NIV (including bilevel and CPAP) have similar effects on outcomes such as the need for intubation and hospital mortality 1. CPAP delivers a constant pressure throughout the respiratory cycle, typically starting at 5-10 cmH2O and titrating up as needed based on patient response. This constant positive pressure helps reduce preload and afterload, improves oxygenation, decreases work of breathing, and recruits collapsed alveoli.

Key Considerations

• CPAP is particularly beneficial in cardiogenic pulmonary edema as it reduces venous return to the heart, effectively functioning as a hemodynamic intervention that decreases cardiac filling pressures.
• BiPAP may be considered if the patient has concurrent hypercapnic respiratory failure or if they fail to improve with CPAP therapy.
• However, BiPAP carries a potentially higher risk of barotrauma and hemodynamic compromise due to its higher inspiratory pressures.
• When implementing CPAP, ensure proper mask fitting, monitor vital signs closely, and be prepared to escalate to endotracheal intubation if the patient's condition deteriorates or they cannot tolerate the mask.

Evidence Summary

The evidence from recent studies, including a large multicentre trial and several systematic reviews, consistently concludes that NIV (including CPAP and bilevel NIV) decreases the need for intubation and is associated with a reduction in hospital mortality 1. While CPAP and NIV have similar effects on these outcomes, CPAP has the advantages of simpler technology, easier synchronization, and potentially less expensive equipment.

Clinical Implications

In clinical practice, the choice between CPAP and BiPAP should be based on individual patient factors, such as the presence of hypercapnic respiratory failure or the patient's ability to tolerate the mask. However, based on the current evidence, CPAP is the preferred initial non-invasive ventilation method for patients with pulmonary edema.

From the Research

Treatment Options for Pulmonary Edema

For a patient with pulmonary edema, the decision to institute CPAP or BIPAP depends on various factors.

• CPAP is a simple technique that may reduce preload and afterload, increasing cardiac output in some patients 2.
• BIPAP, on the other hand, is a more complex mode that requires a ventilator and experience, and has been introduced more recently in the treatment of acute pulmonary edema 2.

Efficacy of CPAP and BIPAP

Studies have shown that both CPAP and BIPAP can improve gas exchange and physiologic parameters in patients with acute pulmonary edema 2, 3.

• CPAP has been shown to reduce intubation rate and mortality in patients with acute cardiogenic pulmonary edema (ACPE) 4, 5, 3.
• BIPAP has also been shown to reduce intubation rate and mortality, although the evidence is not as strong as for CPAP 2, 3.

Choice between CPAP and BIPAP

The choice between CPAP and BIPAP depends on the individual patient's needs and the severity of their condition.

• CPAP may be sufficient for patients with mild to moderate pulmonary edema, while BIPAP may be more suitable for patients with more severe disease or those who require more intensive ventilatory support 2, 6.
• The use of helmet CPAP has been shown to be feasible, efficient, and safe in the pre-hospital treatment of presumed severe ACPE 4.