What are the differences between positive end-expiratory pressure (PEEP) and continuous positive airway pressure (CPAP) measures for the treatment of acute respiratory distress syndrome (ARDS)?

Updated: Mar 27, 2020
  • Author: Eloise M Harman, MD; Chief Editor: Michael R Pinsky, MD, CM, Dr(HC), FCCP, FAPS, MCCM  more...
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Answer

With PEEP, positive pressure is maintained throughout expiration, but when the patient inhales spontaneously, airway pressure decreases to below zero to trigger airflow. With CPAP, a low-resistance demand valve is used to allow positive pressure to be maintained continuously. Positive-pressure ventilation increases intrathoracic pressure and thus may decrease cardiac output and blood pressure. Because mean airway pressure is greater with CPAP than PEEP, CPAP may have a more profound effect on blood pressure.

In general, patients tolerate CPAP well, and CPAP is usually used rather than PEEP. The use of appropriate levels of CPAP is thought to improve the outcome in ARDS. By maintaining the alveoli in an expanded state throughout the respiratory cycle, CPAP may decrease shear forces that promote ventilator-associated lung injury.


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