High-Flow Oxygen Therapy in Tracheostomized Subjects With Prolonged Mechanical Ventilation: A Randomized Crossover Physiologic Study.

BACKGROUND

High-flow oxygen therapy via tracheostomy (HFT) can be used in tracheostomized patients during ventilator disconnection. The physiologic effects of this technique are unknown. We hypothesized that HFT would reduce inspiratory effort and improve breathing pattern compared to conventional oxygen therapy via T-tube. This study aimed to evaluate the physiologic effects of HFT compared to conventional O in patients with prolonged mechanical ventilation.

METHODS

A randomized crossover physiologic study was conducted in adult tracheostomized patients who experienced temporary periods of ventilator disconnection. Subjects were ventilated with pressure support ventilation (PSV) for 15 min and were then randomly assigned to HFT or conventional O via T-tube for 30 min. After a washout period, subjects were switched to the other system. Esophageal pressure (P), breathing frequency, blood pressure, heart rate, [Formula: see text], and transcutaneously measured pressure of carbon dioxide ([Formula: see text]) were recorded. The primary outcome was inspiratory effort as determined by the simplified esophageal pressure-time product (sPTP). Secondary outcomes were P swing, breathing frequency, heart rate, mean arterial pressure, [Formula: see text], and [Formula: see text] between groups.

RESULTS

Twenty-two subjects were enrolled: sPTP per minute was significantly higher with HFT and conventional O compared to PSV (153.5 ± 97.9, 163.5 ± 111.3, and 86.8 ± 51.1 cm HO × s/min, respectively, = .001), but it was not different between HFT and conventional O ( = .72). Breathing frequency increased significantly after switching from PSV to HFT and conventional O (23 ± 4 vs 26 ± 6 and 23 ± 4 vs 27 ± 5 breaths/min, respectively, = .001). [Formula: see text] was higher with conventional O compared to HFT ( = .02). No differences in [Formula: see text], mean arterial pressure, or heart rate were observed between HFT and conventional O.

CONCLUSIONS

Inspiratory effort and breathing frequency increased significantly during unassisted breathing compared to PSV in tracheostomized subjects, but HFT via tracheostomy provided no measurable additional physiologic benefit compared to O therapy via T-tube.