The Spillover Effects of Quality Improvement Beyond Target Populations in Mechanical Ventilation

To assess the impact of a mechanical ventilation quality improvement program on patients who were excluded from the intervention.

Before-during-and-after implementation interrupted time series analysis to assess the effect of the intervention between coronary artery bypass grafting (CABG) surgery patients (included) and left-sided valve surgery patients (excluded).

Academic medical center.

Patients undergoing CABG and left-sided valve procedures were analyzed.

A postoperative mechanical ventilation quality improvement program was developed for patients undergoing CABG.

Patients undergoing CABG had a median mechanical ventilation time of 11 hours during P0 ("before" phase) and 6.22 hours during P2 ("after" phase; p < 0.001). A spillover effect was observed because mechanical ventilation times also decreased from 10 hours during P0 to 6 hours during P2 among valve patients who were excluded from the protocol (p < 0.001). The interrupted time series analysis demonstrated a significant level of change for ventilation time from P0 to P2 for both CABG (p < 0.0001) and valve patients (p < 0.0001). There was no significant difference in the slope of change between the CABG and valve patient populations across time cohorts (P0 vs P1 [p = 0.8809]; P1 vs P2 [p = 0.3834]; P0 vs P2 [p = 0.7672]), which suggests that the rate of change in mechanical ventilation times was similar between included and excluded patients.

Decreased mechanical ventilation times for patients who were not included in a protocol suggests a spillover effect of quality improvement and demonstrates that quality improvement can have benefits beyond a target population.