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By Leslie A. Hoffman, RN, PhD
Professor Emeritus, Nursing and Clinical & Translational Science, University of Pittsburgh
This article originally appeared in the October 2014 issue of Critical Care Alert. It was edited by David J. Pierson, MD, and peer reviewed by William Thompson, MD. Dr. Pierson is Professor Emeritus, Pulmonary and Critical Care Medicine, University of Washington, Seattle, and Dr. Thompson is Associate Professor of Medicine, University of Washington, Seattle. Drs. Pierson and Thompson report no financial relationships relevant to this field of study.
SYNOPSIS: Use of nasal high-flow oxygen was associated with better comfort, fewer desaturations and interface displacements, and a lower reintubation rate.
SOURCE: Maggiore SM, et al. Nasal high-flow versus venturi mask oxygen therapy after extubation. Effects on oxygenation, comfort, and clinical outcome. Am J Respir Crit Care Med 2014;190:282-288.
In this study, 105 patients were randomized to either Venturi mask (n = 52) or nasal high-flow cannula (NHF, n = 53) for oxygen delivery after extubation. Patients were eligible for study entry if they successfully passed a spontaneous breathing trial and had a PaO2/FIO2 ≤ 300 mmHg at the end of the trial. Patients were excluded if they had a tracheostomy or if noninvasive ventilation (NIV) would be used following extubation based on the following criteria: > 3 consecutive failures of a spontaneous breathing trial and a PaCO2 > 45 mmHg with a respiratory rate > 25 breaths/min before the spontaneous breathing trial. Patients were 64 ¡À 17 years of age with a Simplified Acute Physiologic Score II of 43 ¡À 15. Mean duration of mechanical ventilation was 4.9 ¡À 3.9 days. At enrollment, mean PaO2/FIO2 was 240.6 ¡À 46.7 mmHg and mean PaCO2 was 35.3 ¡À 7.3 mmHg.
All outcome variables significantly improved in the NHF group. With NHF, PaO2/FIO2 was significantly higher at 24 hours after extubation (287.2 ¡À 74.3 vs. 247.4 ¡À 80.6 mmHg; P = 0.03), discomfort related to the device was less (P = 0.016), and fewer patients in the NHF group had interface displacements (89 vs. 20; P < 0.001), oxygen desaturation to < 92% detected on the bedside clinical monitor (178 vs. 40; P < 0.001), or required reintubation (11 vs. 2; P < 0.005).
In this study, the most interesting finding relates to the lower reintubation rate in patients randomized to NHF oxygen therapy. There was also a lower incidence of device displacement, a finding that likely resulted from improved comfort with use of the NHF system. During the 48-hour study period, 22 patients experienced post-extubation distress requiring ventilator support, with 4 patients (7.5%) in the NHF group and 18 (34.6%) in the Venturi group. Fewer patients received NIV or required reintubation in the NHF group. In this study, patients expected to require NIV post-extubation were excluded. Thus, those enrolled in the study were expected to tolerate extubation without need for further support. NIV can be used in the post-extubation period to shorten the duration of invasive ventilation, prevent extubation failure, and rescue a failed extubation.
Substantial evidence supports benefit in selected patients. However, use of NIV is somewhat complex and therefore requires an experienced team and adequate personnel and equipment resources. NHF therapy also requires specialized equipment, but is comparatively easier to implement. NHF confers the ability to deliver fully humidified high-flow oxygen (up to 60 L/min) through a nasal cannula. By delivering oxygen at flow rates that exceed the patient’s peak inspiratory flow, the system provides a constant FIO2. In addition, the high gas flow generates the effect of continuous positive airway pressure and results in dead space washout. Through these mechanisms, NHF therapy improves oxygenation and, in comparison to NIV, provides a more comfortable interface. Findings of this study suggest potential benefit in avoiding reintubation through use of NHF therapy in those who experience respiratory distress after extubation.