Plateau Pressure Exceeding Peak Inspiratory Pressure During Pressure Mode Ventilation With Active Inspiratory Effort

Abstract

Background In patients receiving pressure modes of mechanical ventilation, plateau pressure can be higher than peak inspiratory pressure when the patient has a strong drive to breathe. This report provides comprehensive evidence to support this observation. Methods Peak inspiratory pressure, plateau pressure, esophageal pressure, and tidal volume were observed at various levels of pressure support in a patient with absent cortical function but preserved brainstem function who was receiving mechanical ventilation. Results Positive end-expiratory pressure was 5 cm H2O for all pressure support settings. At pressure support of 0 cm H2O, plateau pressure was 13 cm H2O; peak inspiratory pressure was 5 cm H2O. The difference between plateau pressure and peak inspiratory pressure (8 cm H2O) reflected the patient’s inspiratory effort. The driving pressure (8 cm H2O) generated a tidal volume of 619 mL. At pressure support of 10 cm H2O, plateau pressure was 12 cm H2O; peak inspiratory pressure was 15 cm H2O. The difference between plateau pressure and peak inspiratory pressure was –3 cm H2O, indicating absent inspiratory effort apart from triggering the breath. The driving pressure (7 cm H2O) generated a tidal volume of 563 mL. Conclusion When plateau pressure can be accurately measured, the difference between plateau pressure and peak inspiratory pressure can be used at the bedside to evaluate a patient’s respiratory drive. Ensuring protective goals by routinely monitoring plateau pressure regardless of the mode of mechanical ventilation is critical.