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Abstract

Introduction: Successful liberation from mechanical ventilation remains a clinical dilemma when considering predictive factors. This involves evaluating quantitative parameters and qualitative experience of the patient. Spontaneous breathing trials (SBT), which measure aspects of pulmonary function such as respiratory rate and tidal volumes, have been demonstrated as an effective means for assessing weaning probability, albeit more a predictor of failure than success. The limitations of these evaluators may periodically at times be associated with the patient experience of agitation and anxiety while on ventilatory support. Traditional guidelines recommend cessation of all sedatives during weaning, which in turn may amplify the impact of these factors. This study aims to expose a category of patients who may benefit from concurrent sedation to levels that would lead to acceptable SBT demonstration of pulmonary function, affording reasonable opportunity for liberation from mechanical ventilation. Methods: A retrospective chart review was conducted on surgical intensive care unit (SICU) patients using the following inclusion criteria: mechanically ventilated patients at least 18 years old, who failed spontaneous breathing trial (SBT) per our institution protocol. Patients were otherwise hemodynamically stable and without identifiable active pathophysiologic processes contributing to prolonged ventilator dependence. Failure to wean was then attributed to excess anxiety and agitation and the patients underwent repeat SBT along with continuous sedation. Successful weaning was defined as extubation followed by at least 24 hours without reintubation. Results: Twenty-seven patients were identified. One male was excluded. Of the remaining, 22 (84.6%) were successfully weaned and extubated, 4 failed and ultimately required tracheostomy. Both groups were similar regarding hemodynamic status, arterial blood gas values, vent duration and APACHE II Score. Mean Rapid Shallow Breathing Index (RSBI) was 33.86 for all subjects. Glasgow Coma Scale (GCS) for success vs. failures was: 10.73T vs 10.0T (p=0.018). Confidence intervals did overlap between groups. Richmond Agitation and Sedation Scale (RASS) for successes vs. failures was: -0.27 vs. -1.5 (p=0.080). Conclusions: Reliably predicting successful extubation remains imperfect. Despite present guidelines to withdraw all sedation prior to SBT, there exists a potential subgroup of mechanically ventilated patients who could not be confidently liberated unless given a continuous level of mild sedation. This intervention would provide adequate means for patients to overcome the inherently noxious experience of ventilatory support and provide an opportunity to demonstrate their capacity for weaning success. Based on this feasibility study, further exploration of this cohort of immoderately agitated and anxious patients is warranted and may yield a unique exception to currently held precedent.