Table 4.

Association Between Pao₂ During CPB and Respiratory Complications, Cardiac Injury, and Liver Injury

Outcome	GMR/OR (95% CI)a	P value
Respiratory complications	0.87 (0.73–1.03)OR	.11
Cardiac injury
POD 1 troponin levels (ng/mL, after log-transformation)	0.98 (0.95–1.02)GMR	.34
Liver injury
POD 1 total bilirubin (mg/dL, after log-transformation)	1.02 (1.00–1.05)GMR	.07
POD 3 total bilirubin (mg/dL, after log-transformation)	0.99 (0.97–1.01)GMR	.38
POD 7 total bilirubin (mg/dL, after log-transformation)	1.01 (0.98–1.05)GMR	.44

Exploratory analyses assessed the association between TWA of in-line Pao₂ during CPB and (1) respiratory complications, (2) cardiac injury using POD 1 troponin levels, and (3) liver injury using POD 1, 3, and 7 total bilirubin. The effect of in-line Pao₂ during CPB on respiratory complications was assessed through a logistic regression model with direct adjustment of all potential baseline confounders in Table 1. The effect of in-line Pao₂ during CPB on POD 1 troponin levels (after log-transformation) and POD 1, 3, and 7 total bilirubin (after log-transformation) was assessed through linear regression models with direct adjustment of all potential baseline confounders in Table 1.

Abbreviations: CI, confidence interval; CPB, cardiopulmonary bypass; GMR, geometric mean ratio; OR, odds ratio; Pao2, arterial oxygen partial pressure; TWA, time-weighted average.

^aThe OR estimates the change in odds of respiratory complications for each 100-unit change in TWA of in-line Pao₂. The GMRs estimate the change in ratio of geometric means for POD 1 troponin levels and POD 1, 3, and 7 total bilirubin for each 100-unit change in TWA of in-line Pao₂. 95% CI was reported, and P values <.05 were considered significant for exploratory analyses.

Respiratory complications outcome is defined as a composite outcome of postoperative reintubation during the hospital stay, prolonged ventilation, pneumonia, pleural effusion requiring drainage, and pneumothorax requiring intervention.