Objective: Adverse respiratory and gasometrical effects have been described in patients with acute respiratory failure (ARF) undergoing noninvasive ventilation (NIV) with standard heat and moisture exchangers (HME). We decided to evaluate respiratory parameters and arterial blood gases (ABG) of patients during NIV with small dead space HME compared with heated humidifier (HH).
Design: Prospective randomized crossover study.
Setting: A 16-bed medical intensive care unit (ICU).
Patients: Fifty patients receiving NIV for ARF.
Measurements: The effects of HME and HH on respiratory rate, minute ventilation, EtCO(2), oxygen saturation, airway occlusion pressure at 0.1 s, ABG, and comfort perception were compared during two randomly determined NIV periods of 30 min. The relative impact of HME and HH on these parameters was successively compared with or without addition of a flex tube (40 and 10 patients, respectively).
Main results: No difference was observed between HME and HH regarding any of the studied parameters, whether or not a flex tube was added.
Conclusion: If one decides to humidify patients' airways during NIV, one may do so with small dead space HME or HH without altering respiratory parameters.