Flow versus pressure triggering in mechanically ventilated acute respiratory failure patients

Abstract

Background: The effects of flow triggering (FT) compared with pressure triggering (PT) on breathing effort have been the focus of several studies, and discrepant results have been reported; yet, it remains an area of conflict that warrants further studies. Objective: The aim of this work is to compare flow versus PT in ventilating patients with acute respiratory failure. Patients and methods: One hundred patients with acute respiratory failure of pulmonary origin were assigned randomly to two groups: 50 patients ventilated with PT and 50 patients ventilated with FT. The primary end points were weaning duration, evaluation of patient/machine synchronization, total duration of ventilation and ICU stay as well time under sedation and occurrence of complications. Mortality was considered the secondary end point. Patients were categorized into those with obstructive, restrictive, and combined pulmonary disease according to their medical history, and clinical and radiological assessment, and also more and less severe disease according to the APACHE II score level (cut-off point). Results: In all the patients studied, including those with restrictive pulmonary disorder and more severe disease (APACHE II score ≥32.5), there was a statistically significantly shorter duration of weaning, duration of ventilation, and duration of ICU stay in the FT group than the PT group. The pre-extubation oxygenation index was highly statistically significantly better in the FT group than the PT group (P < 0.001). In patients with obstructive pulmonary disorders, combined pulmonary disorders, and less severe disease (APACHE II <32.5), there was no significant difference between both PT and FT groups in these parameters. Conclusion: FT may be considered to be better than PT in ventilating acute respiratory failure patients with a restrictive pattern and those with higher severity scoring. In obstructive and mixed ventilatory impairment, use of either of them does not make a difference.