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

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.