Comparison of Proportional Assist Ventilation Plus, T-Tube Ventilation, and Pressure Support Ventilation as Spontaneous Breathing Trials for Extubation: A Randomized Study.

BACKGROUND: Failure to wean can prolong ICU stay, increase complications associated with mechanical ventilation, and increase morbidity and mortality. The spontaneous breathing trial (SBT) is one method used to assess weaning. The aim of this study was to assess proportional assist ventilation plus (PAV+) as an SBT by comparing its applicability, safety, and efficacy with T-tube and pressure support ventilation (PSV). METHODS: A randomized study was performed involving 160 adult subjects who remained on mechanical ventilation for > 24 h. Subjects were randomly assigned to the PAV+, PSV, or T-tube group. When subjects were ready to perform the SBT, subjects in the PAV+ group were ventilated in PAV+ mode (receiving support of up to 40%), the pressure support was reduced to 7 cm H2O in the PSV group, and subjects in the T-tube group were connected to one T-piece with supplemental oxygen. Subjects were observed for signs of intolerance, whereupon the trial was interrupted. When the trial succeeded, the subjects were extubated and assessed until discharge. RESULTS: The subjects were predominantly male (66.5%), and the leading cause of admission was traumatic brain injury. The groups were similar with respect to baseline characteristics, and no significant difference was observed among the groups regarding extubation success or failure. Analysis of the specificity and sensitivity revealed good sensitivity for all groups; however, the PAV+ group had higher specificity (66.6%) and higher sensitivity (97.6%), with prediction of ∼ 92.1% of the success and failure events. CONCLUSIONS: No significant differences in the groups was observed regarding the rate of extubation failure, duration of mechanical ventilation, and ICU and hospital stay, indicating that PAV+ is an alternative for use as an SBT.

Passive orthostatism (tilt table) in critical patients: Clinicophysiologic evaluation.

PURPOSE: To assess the effects of passive orthostatism on various clinicophysiologic parameters of adult intensive care unit (ICU) patients, by daily placement on a tilt table. MATERIALS AND METHODS: This prospective cohort study was performed in a general ICU. Twenty-three patients 18 years or older, intubated or tracheostomized, without sedation and under weaning from mechanical ventilation, were analyzed. All variables were evaluated at tilting of 30°, 45°, 60°, 75°, and 90°. RESULTS: Glasgow Coma Scale increased during tilt in the first and second day, as well as Richmond Agitation-Sedation Scale. No significant differences were detected in the physiological parameters; however, there was a nonsignificant decrease on the mean arterial pressure at angles of 75° and 90°. The maximum inspiratory pressure significantly increased at 60° compared with 30° on day 1 of the intervention. No significant differences were observed for maximum expiratory pressure, rapid shallow breathing index, and the tidal volume. CONCLUSION: A protocol with daily use of a tilt table for ICU patients is safe and improves the level of consciousness and inspiratory maximum pressure, without causing deleterious acute physiological effects.