Presurgical risk factors for late extubation in Medicare recipients after cardiac surgery

Medicare recipients, particularly those 80 years of age and older, are increasingly undergoing coronary artery bypass grafting surgery (CABGS). There is an association between older age and need for prolonged mechanical ventilation (MV); however, it is unclear what other presurgical characteristics may contribute to prolonged time on the ventilator in older adults.

To develop and validate a probability model for prolonged MV utilizing selected presurgical patient characteristics.

A retrospective, nonexperimental design was utilized to study 548 Medicare recipients (65 years of age or older) undergoing CABGS during 1998. Data were obtained from an existing coronary artery surgery clinical database. RESULTS Based on extubation time, the sample was comprised of two groups (Group 1, N = 205; MV 5 hours). Using logistic regression modeling, predictors of late extubation included: (a). age of 80 years or older (odds ratio [OR] 2.99, p =.003), (b). female sex (OR = 1.76, p =.011), (c). hypertension (OR = 1.60, p =.018), (d). urgent or emergent preoperative clinical status (OR = 3.04, p =.002), and (e). prior CABGS (OR = 2.14, p =.009). The predictive model provided moderate discrimination of time to extubation group (concordance statistic = 0.656).

Older age, urgent or emergent preoperative clinical status, and prior CABGS are risk factors for prolonged MV, which have been consistently identified in combined adult and older adult samples. Female sex and hypertension have not been well supported in earlier studies as risk factors for prolonged MV. The exploratory model provides a preliminary indication of factors placing Medicare recipients at risk for late extubation, but requires further development and testing for use by nurses in clinical practice.