Predictive value of physiologic variables in bedside caregiver initiated extubation of postoperative cardiac surgery patients

Respiratory therapists and nurses (bedside caregivers) often make the decision to extubate patients following cardiac surgery. A potential mechanism to reduce variation, standardize decision-making, and provide an adjunct to the expert bedside caregiver is the use of rule-based computerized decision support tools. The development of these tools necessitates an understanding of the decision-making process, including the information and rules used to generate appropriate recommendations. The aims of the research were: (a) determining the positive and negative predictive values of threshold variables, (b) comparing the predictive power of two different decision models using the threshold values, and (c) determining if the use of threshold values to predict successful extubation is superior to the decisions to extubate made by bedside providers. A retrospective descriptive design was used to evaluate the decision models and the variable thresholds against bedside caregiver decisions to extubate. The medical records of 200 patients undergoing cardiac surgery at two large tertiary care centers in northern Utah were studied. The threshold values studied included FVC/kg > 10ml, V[T]/kg ? 3.5 ml, f ? 26 bpm, V[E] < 10 liters/min,f/V[T] <70, MAP > 70 mm Hg, SvO2 ? 60%, and mediastinal tube drainage ,< 100cc/hr. A decision model requiring one failed threshold to predict failed extubation and a second model predicting failure if two thresholds were not met were evaluated. In addition, the overall failure rate of extubations was evaluated. Analyses of the data suggest that neither model demonstrated improved overall prediction when compared to bedside caregivers. However, both models predicted failed extubations not predicted by the bedside-caregivers. The recommendations of both models resulted in potential delays in extubation. The impact of these delays was not quantified as part of this study. The overall extubation failure rate was 2% for bedside-caregiver extubation.