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Pressure Support vs. T-Piece Ventilation and Extubation of Mechanical Ventilation
Study Questions:
Among mechanically ventilated intensive care unit (ICU) patients, the ability to tolerate a spontaneous breathing trial (SBT) predicts a greater chance of successful extubation. What is the optimum SBT duration and impact of pressure support ventilation (PSV)—given to help overcome the resistance imposed by the endotracheal tube—in relation to the likelihood of extubation success and other clinically important outcomes?
Methods:
ICU patients meeting criteria for ventilatory weaning and attempted extubation after ≥24 hours of mechanical ventilation were enrolled in this trial, and randomly assigned to a 30-minute SBT using 8-cm H2O PSV versus a 2-hour SBT via T-piece without pressure support. The primary outcome was successful extubation without subsequent need for reintubation within 72 hours, and secondary outcomes were reintubation within 72 hours, length of hospital and ICU stay, and hospital and 90-day mortality. Specific clinical decision-making details, including the option of allowing a pre-extubation rest period after the SBT, or post-extubation prophylactic use of high-flow oxygen and/or noninvasive ventilatory support, were established on an individual basis prior to randomization.
Results:
A total of 1,153 adult patients were enrolled between January 2016–April 2017 at multiple centers, with 575 randomized to 30-minute PSV-assisted SBT and 578 randomized to 2-hour T-piece SBT. A total of 1,018 completed the trial. Analysis was by intention-to-treat. A greater proportion of patients in the PSV group was able to tolerate the SBT and be extubated compared to the proportion in the T-piece group (92.5 vs. 84.1%, p < 0.001).
The primary outcome, overall successful extubation without subsequent need for reintubation within 72 hours, occurred more frequently in the PSV versus T-piece group (82.3% vs. 74.0%; hazard ratio 1.54 [1.19-1.97], p < 0.001). Among patients extubated after the SBT, the reintubation rate within 72 hours did not differ significantly by SBT allocation (11.1 vs. 11.9% after PSV vs. T-piece supported SBT), nor did hospital or ICU length of stay. However, the PSV group had significantly lower hospital and 90-day mortality (10.4 vs. 14.9%, p = 0.02, and 13.2 vs. 17.3%, hazard ratio 0.74 [0.55–0.99], respectively). There was a trend toward more frequent use of post-extubation noninvasive ventilation and high flow nasal cannula oxygen in the PSV group, although the difference did not reach statistical significance.
Conclusions:
ICU patients meeting criteria for weaning from mechanical ventilation were more often able to tolerate a shorter (30-minute) SBT with 8-cm H2O pressure support compared to a longer (2-hour) SBT on T-piece. Completion of the shorter, PSV-supported SBT predicted successful extubation with similar frequency as the longer T-piece-supported SBT.
Perspective:
The greater rate of successful extubation among patients receiving 30-minute SBT with 8-cm H2O of pressure support appears to have been driven by greater ability to tolerate the SBT, since the rates of reintubation did not differ significantly among extubated patients according to SBT protocol assignment. Spontaneous breathing through a small endotracheal tube without inspiratory support involves significant expenditure of effort, and failure to tolerate SBT prolongs the duration of mechanical ventilation, thereby increasing exposure to ventilator-related morbidity. However, the findings suggesting lower hospital and 90-day mortality rates after 30-minute PSV-facilitated SBT should be interpreted with caution, given lack of blinding and apparent lack of standardization in the use of supportive adjuncts such as noninvasive ventilation and high-flow nasal cannula oxygen after extubation. Importantly, these results suggest that use of PSV during a 30-minute SBT was well tolerated, and compared to a 2-hour SBT using T-piece, did not lead to any greater rate of post-extubation respiratory failure or other condition necessitating reintubation in a multicenter ICU population.
Keywords: Airway Extubation, Intensive Care Units, Length of Stay, Noninvasive Ventilation, Positive-Pressure Respiration, Primary Prevention, Respiration, Respiration, Artificial, Ventilator Weaning
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