By Betty Tran, MD, MSc
Associate Professor of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine, Chicago
SYNOPSIS: In this secondary analysis of data from a national intensive care unit collaborative, various non-modifiable and modifiable factors were associated with performance of spontaneous awake and breathing trials.
SOURCE: Balas MC, Tan A, Mion LC, et al. Factors associated with spontaneous awakening trial and spontaneous breathing trial performance in adults with critical illness: Analysis of a multicenter, nationwide, cohort study. Chest 2022;162:588-602.
This was a secondary analysis of data collected as part of the Society of Critical Care Medicine ICU Liberation Collaborative consisting of more than 15,000 patients from 68 diverse (community, academic, federal, and private) intensive care units (ICUs).1 The aim of the study was to determine the relative impact of various factors on the performance of a spontaneous awake trial (SAT) and spontaneous breathing trial (SBT). Patients were adults (> 18 years of age) who were in the ICU for at least 24 hours on mechanical ventilation and receiving continuous or intermittently scheduled sedatives. The variables were identified a priori based on published literature, expert opinion, and data available through the collaborative. The primary outcomes were performance of a next-day SAT, where all sedative medications were held, and SBT, defined as a T-piece or tracheostomy collar trial or pressure support (PS) < 7 cm H2O with a positive end-expiratory pressure (PEEP) < 7.5 cm H2O.
In multivariable analyses, non-modifiable factors independently associated with an increased odds of having either a next-day SAT or SBT included older age and a primary admission diagnosis of overdose/withdrawal. In contrast, patients who were overweight or obese and those whose primary ICU diagnosis was sepsis, septic shock, or acute respiratory distress syndrome (ARDS) had lower odds of having a next-day SAT or SBT. Regarding potentially modifiable factors, patients who were deeply sedated and receiving benzodiazepine or ketamine had lower odds of having a next-day SAT or SBT performed. On the other hand, patients who were physically restrained, those with documented sedation targets, those who had arousal assessments more frequently (7-11 times vs. 4-6 times per day) and delirium assessments more frequently (> 4 times per day vs. 2 times per day vs. no assessment), and those receiving dexmedetomidine or propofol were more likely to have a next-day SAT or SBT. In assessing the magnitude of the effect of blocks of predictors, models incorporating patient admission characteristics, with subsequent additions to include ICU practice factors (e.g., family visitation, physical restraint use, frequency of symptom assessments) and pharmacologic treatments were increasingly accurate in predicting next-day SAT or SBT performance based on receiver operative curve analyses. However, predictive accuracy improved even further with the addition of unnamed ICU-specific factors accounting for between-unit variation.
COMMENTARY
Performance of a combined SAT/SBT reduces days on mechanical ventilation, hospital length of stay, and mortality, with a number needed to treat of seven patients to save one life.2 This is the largest study we currently have that examines factors associated with the performance of SATs and SBTs in the ICU. Not surprisingly, patient characteristics, such as admission for sepsis, septic shock, or ARDS, had an impact in terms of next-day SAT/SBT performance, likely because these diagnoses serve as surrogates for more severe illness where patients may not qualify for an SAT or SBT. More importantly, the authors identified several modifiable factors that may serve as targets for practice change and implementation studies. Many of these factors have been identified previously in clinical practice guidelines. Current Pain, Agitation/sedation, Delirium, Immobility (rehabilitation/mobilization), and Sleep (disruption) (PADIS) guidelines recommend daily sedative interruptions and nursing-protocolized-targeted sedation assessments with the goal of maintaining light sedation and support the use of nonbenzodiazepine sedatives due to short-term improvements in ICU length of stay, duration of mechanical ventilation, and delirium.3 What is notable is the finding that even after accounting for patient admission characteristics, symptoms, ICU practice policies, and medications, SAT/SBT performance varied significantly between ICUs, suggesting a significant role for ICU-specific factors. These were not explored in this analysis, but they could include elements such as staffing, unit culture, availability and preferences of attending physicians, and other unmeasured practice patterns, such as criteria used to assess SAT/SBT readiness and unit workflow.
The main limitation to this study is that it is observational; no causal relationships should be inferred. However, the study findings highlight what we already know regarding best practice sedation guidelines in the ICU. Our knowledge gaps include more randomized trials to enhance our management of sedation and delirium in the ICU, the discovery of ICU-specific factors that affect the performance of daily SAT/SBTs, and the best interventional and implementation strategies to target these modifiable determinants with the goal of improving ICU patient outcomes.
REFERENCES
- Pun BT, Balas MC, Barnes-Daly MA, et al. Caring for critically ill patients with the ABCDEF bundle: Results of the ICU Liberation Collaborative in over 15,000 adults. Crit Care Med 2019;47:3-14.
- Girard TD, Kress JP, Fuchs BD, et al. Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): A randomised controlled trial. Lancet 2008;371:126-134.
- Devlin JW, Skrobik Y, Gelinas C, et al. Clinical practice guidelines for the prevention and management of pain, agitation/sedation, delirium, immobility, and sleep disruption in adult patients in the ICU. Crit Care Med 2018;46:e825-e873.
