Flow triggering added to pressure support ventilation improves comfort and reduces work of breathing in mechanically ventilated patients.

Overview

PURPOSE: The purpose of this study was to measure the effect of flow triggering (FT), added to pressure support ventilation (PSV), during spontaneous breathing in intubated patients. MATERIALS AND METHODS: A prospective observational study was conducted at a Comprehensive Cancer Center, University Hospital. Fourteen consecutive critically ill, mechanically ventilated patients on PSV with positive end-expiratory pressure were studied. Flow triggering was added to PSV in spontaneously breathing ventilated patients. RESULTS: Respiratory rate (f), minute ventilation (Vepsilon), patient work of breathing (WOBp), respiratory drive (P0.1), rapid shallow breathing index (f/Vt), tidal volume (Vt) and a visual analog scale of breathing effort and comfort all improved. There was a large decrease in WOBp and P0.1 when flow triggering was added to PSV (P<.001). There was a moderate decrease in f/V1 during the same procedure (P<.01). Twelve patients felt subjectively better with the intervention. CONCLUSIONS: Flow triggering offers an excellent complement to PSV because it improves patient comfort and reduces the magnitude of the inspiratory effort as well as the delay time between inspiratory muscle contraction and gas flow. It augments gas exchange at no metabolic cost to the patient while reducing the work of breathing.