The effect of varying inspiratory flow waveforms on pulmonary mechanics incritically ill patients

Purpose: Ten mechanically ventilated patients were evaluated to determine t he effect of three different inspiratory flow patterns on pulmonary mechani cs. Materials and Methods:Ten consecutive mechanically ventilated critically il l patients with acute respiratory failure admitted to the intensive care un it were evaluated to assess the effects of decelerating, square, and sine w aveforms on pulmonary mechanics, The variables measured were peak airway pr essure (PaW), pleural pressure (Ppi), change in peak airway pressure (dPaW) , inspiration time/total ventilation cycle time (Vi/Vtot), dynamic complian ce (Cdyn), respiratory rate (RR), minute ventilation (Ve), and work of brea thing (WOB). Results:The PaW, Ppl, and dPaW (cm H2O) were significantly lower using the decelerating inspiratory flow waveform (P <.05) compared with sine or squar e waveform patterns. Ti/Ttot was also lower with the decelerating waveform (P <.05) with better dynamic compliance compared with the other waveforms ( P < Conclusions: These results indicate that critically ill mechanically ventil ated patients show improved respiratory mechanics with decelerating inspira tory waveform that may have beneficial clinical implication. Copyright (C) 2000 by W.B. Saunders Company.