Does off-pump surgery offer benefit in high respiratory risk patients A respiratory risk stratified analysis in a propensity-matched cohort

Objective: The role of off-pump surgery in high respiratory risk patients remains unclear. In this study, we aim to evaluate the effect of off-pump surgery on high respiratory risk patients. Methods: To achieve comparative groups, a five digit propensity score matching with 18 preoperative variables was performed on 4406 consecutive CABG patients operated between January 2000 and September 2003. Respiratory risk stratification was performed with the following variables: (1) FEV 1 75 years old, (3) history of current smoking, (4) body mass index more than 40 kg/m 2 and (5) NYHA class IV dyspnoea in combination with current respiratory medication. The presence of two or more variables defined high risk. The primary end point was post-operative ventilation time. We also compared alveolar arterial gradients (A-a gradient) on admission to ITU, 2 and 4 h using Friedman rank time analysis. Results: We matched 1353 off-pump patients with 1353 unique on-pump patients. Respiratory risk stratified selection resulted in 73 off-pump and 55 on-pump high-risk patients. In the off-pump group, four (5.5%) patients had more than two selection criteria, compared to one (1.8%) for on-pump patients (p = 0.29). The off-pump group had more patients with FEV1 48 h compared to eight (14.6%) in the on-pump group, p = 0.037. A-a gradient measurements on admission to ITU were lower in off-pump patients (median: 182.3 [IQR: 126.6-216.2]) compared to on-pump patients (median: 194.7 [IQR 139.7-245.4], p = 0.064). Conclusion: Off-pump surgery offers benefit to high respiratory risk patients by reducing post-operative ventilation time. Off-pump patients also have lower A-a gradients in the early post-operative period but this failed to reach significance.