Risk factors for and economic implications of prolonged ventilation after cardiac surgery

Objective

The study’s objective was to identify predictors of prolonged ventilation and assess clinical and cost implications in patients undergoing cardiac surgery.

Methods

Patients undergoing cardiac surgery were classified as (1) ventilated less than 96 hours or (2) ventilated 96 hours or more. Multivariate modeling was used to identify predictors of prolonged ventilation and to ascertain the impact of prolonged ventilation on in-hospital mortality and bed occupancy costs and 5-year survival.

Results

A total of 7553 patients were studied; 197 (2.6%) had prolonged ventilation. Median ventilation times were 8 and 192 hours, and in-hospital mortality was 1.0% and 22.2% in the control and prolonged ventilation groups, respectively (P < .001). In-hospital mortality remained higher in the prolonged ventilation group after adjustment and when comparing propensity-matched patients (odds ratio 8.06; 95% confidence interval [CI] 4.27-15.2; P < .001 for propensity-matched groups). Independent predictors of prolonged ventilation were as follows: older age, New York Heart Association class, ejection fraction less than 50%, creatinine greater than 200 μmol/L, multiple valve replacements, aortic procedures, operative priority, reoperation for bleeding, inotropes, and preoperative intra-aortic balloon pump. Five-year survival was lower in the prolonged ventilation group (56.1% [95% CI 46.6%-64.6%] vs 88.8% [95% CI 87.9%-89.6%]) also after adjustment for imbalances and when comparing propensity-matched patients (hazard ratio 2.39; 95% CI 1.75-3.27; P < .001 for propensity-matched groups). Mean bed occupancy costs were $14,286 (95% CI $12,731-$15,690) and $2761 (95% CI $2705-$2814) in the prolonged ventilation and control groups, respectively (P < .001).

Conclusion

Prolonged ventilation is associated with high in-hospital mortality and costs, and poor 5-year survival. Identified predictors of prolonged ventilation might help to optimize the clinical management of these patients.

Abbreviations and Acronyms:  CI, confidence interval , CPB, cardiopulmonary bypass , HDU, high-dependency unit , ICU, intensive care unit , NSTS, National Strategic Tracing Service , NYHA, New York Heart Association , PV, prolonged ventilation