The effect of varying inspiratory flow waveforms on pulmonary mechanics in critically ill patients.
OBJECTIVE
Ten mechanically ventilated patients were evaluated to determine the effect of three different inspiratory flow patterns on pulmonary mechanics.


METHODS
Ten consecutive mechanically ventilated critically ill patients with acute respiratory failure admitted to the intensive care unit were evaluated to assess the effects of decelerating, square, and sine waveforms on pulmonary mechanics. The variables measured were peak airway pressure (PaW), pleural pressure (Ppl), change in peak airway pressure (dPaW), inspiration time/total ventilation cycle time (Vi/tot), dynamic compliance (Cdyn), respiratory rate (RR), minute ventilation (Ve), and work of breathing (WOB).


RESULTS
The PaW, Ppl, and dPaW (cm H2O) were significantly lower using the decelerating inspiratory flow waveform (P<.05) compared with sine or square waveform patterns. Ti/Ttot was also lower with the decelerating waveform (P<.05) with better dynamic compliance compared with the other waveforms (P<.10).


CONCLUSIONS
These results indicate that critically ill mechanically ventilated patients show improved respiratory mechanics with decelerating inspiratory waveform that may have beneficial clinical implication.
Wong
P W
PW
Department of Anesthesiology and Critical Care Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
Nygard
S
S
Sogoloff
H
H
Groeger
J S
JS
Barrera
R
R
D000328:Adult; D000368:Aged; D006801:Humans; D007362:Intensive Care Units; D016014:Linear Models; D008875:Middle Aged; D012121:Respiration, Artificial / Q000379:methods*; D012131:Respiratory Insufficiency / Q000628:therapy*; D015656:Respiratory Mechanics