NIPPV in Acute Cardiogenic Pulmonary Edema – CPAP or BiPAP?
Pathophysiology of Acute Cardiogenic Pulmonary Edema (ACPE)
Pulmonary vascular congestion, interstitial edema, and alveolar fluid accumulation, which initially leads to hypoxemic respiratory failure but can progress to hypercapnic respiratory failure.
Benefits of NIPPV in ACPE
- Reduces work of breathing
Recruits and stabilizes collapsed alveoli
Increases intrathoracic and hydrostatic pressure, moving fluid from the lungs into the vasculature
Increases tidal volume and minute ventilation, increasing PaO2 and decreasing PaCO2
Modes of NIPPV
Continuous Positive Airway Pressure (CPAP)
- Delivers a constant pressure throughout the respiratory cycle
Typically set between 5-15 cm H2O
Bilevel Positive Airway Pressure (BiPAP)
- Delivers different levels of pressure during the inspiratory phase and the expiratory phase
Inspiratory positive airway pressure (IPAP) is typically set to 8-10 cm H2O
Expiratory positive airway pressure (EPAP) is typically set to 3-5 cm H2O
CPAP or BiPAP?
A meta analysis published in the Annals of Internal Medicine in 2010 found that both CPAP and BiPAP reduced the need for intubation when compared to standard therapy alone. However, a mortality benefit was only seen with CPAP.
CPAP, when compared to standard therapy, reduced mortality (RR 0.64, CI 0.44-0.92) and the need for intubation (RR 0.44, CI 0.32-0.6).
BiPAP, when compared to standard therapy, reduced the need for intubation (RR 0.54, CI 0.33-0.86) but was not found to reduce mortality.
Evidence points to CPAP as the superior method of NIPPV in ACPE, as it reduces both the need for intubation and mortality.
ACEP practice guidelines currently offer a Level B recommendation for the use of CPAP and Level C recommendation for BiPAP in dyspneic patients with acute heart failure syndromes.
Silvers, Scott M., John M. Howell, Joshua M. Kosowsky, Ivan C. Rokos, and Andy S. Jagoda. "Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department with Acute Heart Failure Syndromes." Annals of Emergency Medicine 49.5 (2007): 627-69. Web.
Tintinalli, J. E., Stapczynski, J. S., Ma, O. J., Yealy, D. M., Meckler, G. D., & Cline, D. (2016).Tintinalli's emergency medicine: a comprehensive study guide. New York: McGraw-Hill Education.
Weng C, Zhao Y, Liu Q et al. Meta-analysis: noninvasive ventilation in acute cardiogenic pulmonary edema. Ann Intern Med 2010;152:590-600.