Effect of perfusate oxygenation on inflammatory response in congenital heart disease children from low versus high altitude.

Abstract

To examine the altitude differences in the optimal perfusate oxygenation (PpO₂) in patients who underwent cardiac surgery. We included children (aged 1 month to 18 years) with congenital heart diseases surgically repaired between 2012 and 2018. We included only patients who underwent cardiac surgery with arrested heart cardiopulmonary bypass. Primary outcome was severe systemic inflammatory response syndrome (SIRS). Logistic regression was used to evaluate the association between arterial PpO₂ on continuous and categorical scales and severe SIRS by altitude. We established PpO₂ thresholds that equated to a risk probability of roughly 0.185 or greater for developing severe SIRS in each group of altitude. Among 3918 patients from low altitudes and 2384 from high altitudes, high-altitude patients were older (median, 42.3 [interquartile range 22.8-75.8] vs 37.1 [17.7-69.1] months, P < .001) and had lower arterial PpO₂ (289 [237-342] vs 301 [246-362] mm Hg, P < .001). Greater PpO₂ was associated with increased risk of severe SIRS overall (adjusted odds ratio, 1.221 [95% confidence interval, 1.167-1.278] per standard deviation increase), with a stronger monotonic associations for low-altitude patients than for high-altitude patients (adjusted odds ratio, 1.302 [95% confidence interval, 1.229-1.379] vs adjusted odds ratio, 1.083 [95% confidence interval, 1.003-1.170] per standard deviation increase) (P_interaction = .0003). A PpO₂ level of 310 mm Hg identified low-altitude patients with a risk probability of roughly 0.185 or greater of severe SIRS, whereas the cutoffs ranged from 200 mm Hg to 325 mm Hg for high-altitude patients. This study suggests altitude differences in the association of arterial PpO₂ with inflammatory response following pediatric cardiac surgery.