Purpose: Little is known regarding precise estimates of the association between perfusate oxygenation (PpO2) and acute lung injury (ALI) following tetralogy of Fallot repair. The objective is to investigate PpO2 and the risk of ALI following tetralogy of Fallot repair in pediatric patients.
Methods: We conducted a nested case-control study within a prospective Chinese TedaICH cohort including 134 ALI patients aged 1 month to 18 years undergoing complete repair of tetralogy of Fallot, and each was matched to two controls. We selected the highest PpO2 during aortic crossclamp as the exposure. Conditional logistic regression was used to quantify the association between PpO2 and overall ALI risk by covariates of interest. We identified and integrated the risk covariates to build ALI nomograms and internally validated the nomograms using bootstrapping.
Results: After adjusting for covariates, continuously and categorically higher PpO2 values were associated with ALI risk (all P < 0.05), especially for those with a z-score of pulmonary annulus < -4.0 (P = 0.002), McGoon ratio < 1.5 (P = 0.029), and major aortopulmonary collateral arteries (P = 0.005), despite no statistical heterogeneity (all P interaction >0.05). Younger age, lower oxyhemoglobin saturation, untreated minor aortopulmonary collateral arteries, transannular patch, larger transpulmonary gradient, major transfusion, and longer cardiopulmonary bypass time were independent risk factors for ALI (all P < 0.05). Combining the PpO2 nomogram provided further risk discriminative information on ALI diagnosis compared with the covariate-based nomogram alone in the training cohort (AUC 0.865, 95% CI [0.828-0.903] vs. 0.869 [0.832-0.906], respectively) with no statistical significance (P = 0.445).
Conclusions: The findings suggested an association between high PpO2 and ALI risk, and more importance should be attached to independent risk factors for ALI.