Does Aspirin Use Influence Exacerbations and Morbidity of Chronic Obstructive Pulmonary Disease?

Abstract

M echanical ventilation is used often in the intensive care unit (ICU). The term “weaning” is still used to describe the gradual process of decreasing ventilator support but the spontaneous breathing trial (SBT), an assessment of the patient’s ability to breathe while receiving minimal or no ventilator support (eg, 5 cmH2O pressure support and 5 cmH2O end-expiratory pressure),1 is often the decision point for when to extubate a patient. A “T-piece” trial is literally removing the patient from the ventilator but keeping the endotracheal tube in place with supplemental oxygen, only. This requires the patient to ventilate through the tube, but without any extra pressure support, at all. Although many studies performed have failed to show a significant difference in the success of extubation between T-piece and pressure support ventilation (PSV) trials, it is generally accepted that patients tolerate a shorter SBT trial. In this paper, Subirá and colleagues hypothesized that less demanding SBTs could result in higher rates of successful extubation without increasing reintubation rates. To test their hypothesis, they implemented 2 different weaning strategies: a more demanding 2-hour T-piece trial versus a less demanding SBT using 8 cm H2O with zero positive end-expiratory pressure for 30 minutes. The study was conducted over a 16-month period (January 2016 to April 2017) in 18 Spanish ICUs. The patients were randomized into one of the weaning strategies; however, before randomization, the attending physicians had to decide on the extubation strategy. Extubation strategies included reconnecting the patient to the ventilator for 1 hour after the weaning test before attempting extubation and the administration of nasal intermittent positive pressure ventilation or high-flow nasal cannula after extubation. Patients successfully completing an SBT were extubated, no arterial blood gases were required, and they utilized the Borg Dyspnea Scale to record reported dyspnea at the beginning and end of the SBT. Patients who failed SBT were placed back on the ventilator. During the study period, a total of 2649 patients received mechanical ventilation for at least 24 hours in the participating ICUs. Of the 2649 patients, 1501 fulfilled the inclusion criteria, with 578 patients undergoing randomization to undergo a 2-hour T-piece SBT and 575 patients were randomized to undergo a 30-minute SBT with 8 cmH2O PSV. The study team defined successful extubation as remaining free of mechanical ventilation for 72 hours after extubation, which occurred in 473 patients (82.3%) in the PSV group and 428 patients (74%) in the T-piece group. There was a significant difference between the 2 groups, with a higher successful extubation rate in the PSV group. Reintubation within 72 hours occurred in 59 patients (11.1%) in the PSV group, with a median time of 23 hours, whereas reintubation occurred in 58 patients (11.9%) in the T-piece group, with a median time of 24.5 hours. Reasons for reintubation were not significantly different between the 2 groups, and excessive work of breathing was the most common cause in both groups. Of note, the study team noted that mortality at 90 days was significantly lower in the PSV group (13.2%) compared with the T-piece group (17.3%). Weaning protocols can vary among ICUs, but the main goal is to assess whether the patient can be extubated safely and remain so for the remainder of their hospital course. Among intensivists, the preferences for utilizing a PSV or T-piece approach for the SBT are highly variable. Previous literature has concluded that T-piece SBTs reflect the physiological condition and should be preferentially used.2 In addition, there were anecdotal reports suggesting that patients who tolerate PSV well could develop respiratory failure immediately after extubation.3 In this study, Subirá and colleagues have shown the opposite—patients tolerated the PSV better than T-piece during SBT without significant rates of reintubation or other postextubation complications. The authors do acknowledge the limitations of the study, which include the prophylactic use of nasal intermittent positive pressure ventilation and high-flow nasal cannula after extubation without protocol, instances of extubation outside of the protocol, and that the investigators and attending physicians were not blinded to the treatment randomization group. Even though this study shows promising results with regard to successful extubation with the use of PSV SBTs, the limitations are significant, and further investigation is required before these strategies can be implemented among ICUs in their weaning protocols.