Effect of Pressure Support vs T-Piece Ventilation Strategies During Spontaneous Breathing Trials on Successful Extubation Among Patients Receiving Mechanical Ventilation: A Randomized Clinical Trial.

Importance: Daily spontaneous breathing trials (SBTs) are the best approach to determine whether patients are ready for disconnection from mechanical ventilation, but mode and duration of SBT remain controversial. Objective: To evaluate the effect of an SBT consisting of 30 minutes of pressure support ventilation (an approach that is less demanding for patients) vs an SBT consisting of 2 hours of T-piece ventilation (an approach that is more demanding for patients) on rates of successful extubation. Design, Setting, and Participants: Randomized clinical trial conducted from January 2016 to April 2017 among 1153 adults deemed ready for weaning after at least 24 hours of mechanical ventilation at 18 intensive care units in Spain. Follow-up ended in July 2017. Interventions: Patients were randomized to undergo a 2-hour T-piece SBT (n = 578) or a 30-minute SBT with 8-cm H2O pressure support ventilation (n = 557). Main Outcome and Measures: The primary outcome was successful extubation (remaining free of mechanical ventilation 72 hours after first SBT). Secondary outcomes were reintubation among patients extubated after SBT; intensive care unit and hospital lengths of stay; and hospital and 90-day mortality. Results: Among 1153 patients who were randomized (mean age, 62.2 [SD, 15.7] years; 428 [37.1%] women), 1018 (88.3%) completed the trial. Successful extubation occurred in 473 patients (82.3%) in the pressure support ventilation group and 428 patients (74.0%) in the T-piece group (difference, 8.2%; 95% CI, 3.4%-13.0%; P = .001). Among secondary outcomes, for the pressure support ventilation group vs the T-piece group, respectively, reintubation was 11.1% vs 11.9% (difference, -0.8%; 95% CI, -4.8% to 3.1%; P = .63), median intensive care unit length of stay was 9 days vs 10 days (mean difference, -0.3 days; 95% CI, -1.7 to 1.1 days; P = .69), median hospital length of stay was 24 days vs 24 days (mean difference, 1.3 days; 95% CI, -2.2 to 4.9 days; P = .45), hospital mortality was 10.4% vs 14.9% (difference, -4.4%; 95% CI, -8.3% to -0.6%; P = .02), and 90-day mortality was 13.2% vs 17.3% (difference, -4.1% [95% CI, -8.2% to 0.01%; P = .04]; hazard ratio, 0.74 [95% CI, 0.55-0.99]). Conclusions and Relevance: Among patients receiving mechanical ventilation, a spontaneous breathing trial consisting of 30 minutes of pressure support ventilation, compared with 2 hours of T-piece ventilation, led to significantly higher rates of successful extubation. These findings support the use of a shorter, less demanding ventilation strategy for spontaneous breathing trials. Trial Registration: ClinicalTrials.gov Identifier: NCT02620358.

Proportional assist ventilation feasibility in the early stage of respiratory failure: a prospective randomized multicenter trial.

BACKGROUND: Proportional assist ventilation (PAV+) is an assisted ventilator mode usually applied during weaning. We aimed to determine the feasibility of using PAV+ in the early phase of acute respiratory failure compared to volume-assist control ventilation (V-ACV) in order to shorten the length of mechanical ventilation (MV). METHODS: We conducted a prospective randomized trial comparing high-assistance PAV+ (gain 80%) vs. V-ACV in four university hospital Intensive Care Units. Patients were included based on a previous pilot trial. Length of MV was the main objective. Secondary objectives were length of stay (LOS) in ICU/hospital, and ICU/hospital/60-day mortality. Statistics - Mann-Whitney U Test and Fisher's Exact Test. RESULTS: We could not find differences in length of MV or any of the analyzed variables between the 52 patients with PAV+ and 50 patients with V-ACV. The high PAV+ failure rate (42%) was attributed to excessive sedation, high respiratory rate, and high respiratory effort. CONCLUSIONS: The use of high-assistance PAV+ in the early phase of MV does not present benefits compared to V-ACV. The high rate of PAV+ failure reinforces the need for sedative optimization, learning curve, and better patient selection.

Electrical impedance tomography.

Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations. It may also quantify gains (recruitment) and losses (overdistention or derecruitment), granting a more realistic evaluation of different ventilator modes or recruitment maneuvers, and helping in the identification of responders and non-responders to such maneuvers. Moreover, EIT also contributes to the management of life-threatening lung diseases such as pneumothorax, and aids in guiding fluid management in the critical care setting. Lastly, assessment of cardiac function and lung perfusion through electrical impedance is on the way.