Lower pass threshold (≥93%) for critical congenital heart disease screening at high altitude prevents repeat screening and reduces false positives

OBJECTIVE: We evaluated first screen pass rate for two pass thresholds for critical congenital heart disease (CCHD) oxygen saturation (SpO(2)) screening at higher altitude. STUDY DESIGN: A retrospective cohort of 948 newborns underwent CCHD screening near sea-level (n = 463) vs 6250 ft altitude (n = 485) over 3 years. Standard SpO(2) pass threshold ≥95% and lower SpO(2) pass threshold ≥93% (high-altitude screen) were applied to first measurements to compare pass frequencies. RESULTS: The median SpO(2) was lower in high-altitude newborns (96% vs 99%—p < 0.001). The high-altitude newborns passed the AAP algorithm first screen less often (89.3% vs 99.6%—p < 0.001). With the high-altitude algorithm, 98% of high-altitude newborns passed the first screen. CONCLUSION: Lowering the SpO(2) pass threshold by 2% at >6000 ft, significantly increased first screen pass rate. Adjustments for altitude may reduce nursing time to conduct repeat measurements and prevent transfers for echocardiograms. Larger studies are necessary to assess impact on false negatives.