FROM JAMA
Extubated patients who either received noninvasive ventilation (NIV) therapy or high-flow nasal cannula oxygen had a lower risk of reintubation, compared with extubated patients who received some form of standard oxygen therapy, according to the results of two multicenter, randomized clinical trials published online in JAMA.
Participants in one of the studies, which included abdominal surgery patients diagnosed with respiratory failure within 7 days following surgery, either received NIV or standard oxygen therapy for 30 days or until ICU discharge, whichever came first. While NIV has been effectively used to treat nonsurgical patients with acute exacerbations of chronic obstructive pulmonary disease and cardiogenic pulmonary edema, there is no evidence to support the use of NIV in surgical patients with hypoxemic acute respiratory failure after abdominal surgery, according to Dr. Samir Jaber of the Saint Eloi University Hospital and Montpellier School of Medicine, both in Montpellier, France, and his colleagues ( JAMA. 2016 Apr 5;315[13]:1345-53 ).
The second study included adult patients who had received mechanical ventilation for more than 12 hours and who met criteria for being considered at low risk for reintubation. Patients were administered either high-flow oxygen therapy through nasal cannula immediately after extubation or continuous conventional oxygen therapy through nasal cannula or nonrebreather facemask; the patients were observed for 72 hours. High-flow therapy has been shown to improve oxygenation and survival in clinical studies of critically ill patients in the acute phase of respiratory failure. “[A study by S.M. Maggiore and his colleagues ( Am J Respir Crit Care Med. 2014;190(3):282-8 )] suggested that high-flow therapy after planned extubation decreased the reintubation rate in a general population of critical patients, but the benefits might be mainly attributable to improvements in high-risk patients,” said Dr. Gonzalo Hernandez, of the Hospital Virgen de la Salud, Toledo, Spain, and his colleagues ( JAMA. 2016 Apr 5;315[13]:1354-61 ).
In the first study, 148 patients received NIV and 145 patients received standard oxygen therapy only. NIV was administered through a facemask connected to an ICU- or a NIV-dedicated ventilator, using either a heated humidifier or heat and moisture exchanger to warm and humidify inspired gases. Patients were encouraged to use NIV for 6 hours during the first 24 hours of the study and received standard oxygen therapy at a rate of up to 15 L/minute to maintain an arterial oxygen saturation estimate (SpO2) of at least 94% in between NIV sessions. NIV was started at an inspiratory positive airway pressure of 5 cm H2O, increasing to a maximum inspiratory pressure of 15 cm H2O, aiming to achieve an expiratory tidal volume between 6 and 8 mL/kg of predicted body weight and a respiratory rate lower than 25/min. The patients in this study’s control group only received the standard oxygen therapy.
In the other study, 263 patients received conventional therapy, with the oxygen flow having been adjusted to maintain an arterial oxygen saturation estimate of greater than 92%. This study’s other 264 patients received high-flow oxygen therapy, with the flow having been initially set at 10 L/min and titrated upward in 5-L/min steps until patients experienced discomfort. The high-flow therapy was stopped after 24 hours and was followed by conventional oxygen therapy, when needed.
The primary outcome measure in the study involving NIV was cause for reintubation within 7 days of randomization.
Secondary outcome measures included gas exchange, healthcare-associated infection rate within 30 days, number of ventilator-free days between days 1 and 30, antibiotic use duration, ICU and in-hospital length of stay, and 30- and 90-day mortality.
Reintubation occurred in 49 patients in the NIV group and 66 patients in the standard oxygen therapy group, a significant difference (P = .03). Among the reintubated patients, those who had received NIV spent less time under invasive mechanical ventilation as did the patients given standard oxygen therapy. The interquartile ranges of days of invasive mechanical ventilation were 0-3 for patients in the NIV group and 0-5 for patients in the standard oxygen therapy group (P = .05). At 30 days, NIV was associated with significantly more ventilator-free days than standard oxygen therapy (25.4 vs. 23.2; P = .04). At 90 days, 22 patients in the NIV group and 31 patients in the standard oxygen therapy group had died (P = .15).
“Recent high-impact trials have demonstrated the benefits of nonsurgical hypoxemic respiratory failure or equivalence of high-flow nasal cannula compared with NIV in patients after cardiothoracic surgery with moderate to severe hypoxemia. Future studies comparing use of high-flow oxygen cannula vs standard oxygen therapy and NIV in patients after abdominal surgery as preventive (prophylactic) or curative applications are needed,” according to Dr. Jaber and his colleagues.
The primary outcome measure for the study of patients receiving high-flow oxygen therapy was reintubation within 72 hours after extubation; this occurred in fewer patients in the high-flow oxygen group than in the conventional therapy group (13 or 4.9% vs. 32 or 12.2%.) This statistically significant difference was mainly attributable to a lower incidence of respiratory-related reintubation in the high-flow group, compared with the conventional therapy group (1.5% vs. 8.7%), said Dr. Hernandez and his colleagues.
Secondary outcome measures included postextubation respiratory failure, respiratory infection, sepsis, multiorgan failure, ICU and hospital length of stay and mortality, time to reintubation, and adverse effects. Postintubation respiratory failure was less common in the high-flow therapy group than in the conventional therapy group (22 patients or 8.3% vs. 38 or 14.4%). Differences between the two groups in other secondary outcomes were not statistically significant.
“The main finding of this study was that high-flow oxygen significantly reduced the reintubation rate in critically ill patients at low risk for extubation failure … High-flow therapy improves oxygenation, and the lower rate of reintubation secondary to hypoxia in the high-flow group corroborates this finding. High-flow oxygen also seems to reduce other causes of respiratory failure such as increased work of breathing and respiratory muscle fatigue, which are frequently associated with reintubation secondary to hypoxia. Another way in which high-flow therapy improves extubation outcome is by conditioning the inspired gas,” said Dr. Hernandez and his colleagues.
No adverse events were reported in either study.
Dr. Hernandez and his colleagues reported no conflicts of interest. Dr. Jaber and his colleagues disclosed no potential conflicts of interest with their study’s sponsors, Montpellier (France) University Hospital and the APARD Foundation.
