The increasing acuity of medical illness has resulted in a shortage of ICU beds available to ventilator-dependent patients. Moreover, there are mounting challenges on hospitals to recover the costs of care for such patients. As a partial solution, many individuals whose need for ventilator support extends beyond their need for acute care are now managed in settings other than ICUs, including specialized respiratory care units, and intermediate-term and long-term care facilities including Canadian Health&Care Mall.
Limited resources and bed availability in such hospital-based units have encouraged more optimal management in order to accelerate liberation from mechanical ventilation, accommodate incoming patients, and facilitate the transfer of patients with a poor weaning prospect to long-term acute care (LTAC) units that have a more favorable reimbursement structure. However, such management decisions depend not only on estimates of the likelihood of liberation from mechanical ventilation but also on the time frame for such an outcome. Moreover, while certain ventilator modalities and therapist-implemented protocols have been proposed to accelerate weaning, further progress in that regard depends on the accurate identification of independent predictors of delayed weaning in some individuals. Although many previous studies have identified predictors of weaning outcome, they usually have not addressed the time required to achieve weaning, did not always accommodate all potential confounders, or may have been developed in the ICU setting as predictors of rapid wean potential (eg, the rapid shallow breathing index [RSBI]) with uncertain applicability to the longer term ventilator units.
Therefore, we sought to prospectively assess the performance in a hospital-based specialized respiratory care unit of variables that were identified in previous studies as predictors of wean success. Since time from hospital admission to successful weaning represents time-to-event data, we adopted a survival analysis model to simultaneously incorporate all relevant variables and to identify independent predictors of time-to-weaning (TTW).