Ventilator gas delivery wave form substantially impacts plateau pressure and peak-to-plateau pressure gradient determination.

Background: To determine whether plateau pressure (Pplat) measurement is lowered and peak airway pressure (Pawpeak)-to-Plat gradient is increased by measurement on a decelerating compared with square gas delivery wave form.

Methods: Prospective before and after study of mechanically ventilated injured and critically ill patients in an adult surgical intensive care unit. Pplat, Pawpeak, and Pawpeak-to-Pplat gradient were measured on decelerating and square gas delivery wave forms.