The effects of postoperative hematocrit on shunt occlusion for neonates undergoing single ventricle palliation

Objectives Our primary objective was to test the effects of first postoperative hematocrit on early shunt occlusion for children undergoing systemic to pulmonary artery shunt placement. Because any intervention to reduce shunt occlusion is only beneficial if it reduces mortality or is, at least, mortality neutral, we also tested the effects of first postoperative hematocrit on in-hospital mortality. Methods We conducted a retrospective study on all neonates who underwent primary systemic to pulmonary artery shunt placement, with or without a Norwood/Damus–Kaye–Stansel procedure, at Columbia University Medical Center between January 2010 and July 2015. Univariable regression was used to test the effects of first postoperative hematocrit on early shunt occlusion and 30-day mortality, clustering standard errors by surgeon. In secondary analyses, we also tested associations between red blood cell transfusion volumes in the first 24 postoperative hours and first postoperative hematocrit, shunt occlusion, and mortality. Results Eighty infants met inclusion criteria. Median initial postoperative hematocrit was 41.7% (interquartile range, 37.9-46.0). Six infants (7.5%) died. Four infants (5.0%) died within the first 30 days. Five infants (6.3%) experienced early shunt occlusion. No children with early shunt occlusion died. In univariable models, for every 5 additional percentage points of hematocrit, an infant's odds of early shunt occlusion more than doubled (odds ratio, 2.70; P = .009). The odds of all-cause 30-day mortality remained unchanged. Conclusions Higher postoperative hematocrit levels are associated with early shunt occlusions in infants undergoing primary systemic to pulmonary artery shunt placement. Multicenter investigations are warranted to validate these findings and to determine ideal postoperative hematocrit targets for this population.