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

Abstract

Objective: We evaluated first screen pass rate for two pass thresholds for critical congenital heart disease (CCHD) oxygen saturation (SpO₂) 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 SpO₂ pass threshold ≥95% and lower SpO₂ pass threshold ≥93% (high-altitude screen) were applied to first measurements to compare pass frequencies.

Results: The median SpO₂ 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 SpO₂ 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.

Fig. 1. Modified high altitude oxygen saturation critical congenital heart disease screening.

Modified algorithm allows for physician to determine if an echocardiogram should be obtained for oxygen saturation ≤90% before repeating the screen. However, the physician must be notified for the oxygen saturation ≤90% whereas an oxygen saturation 91–92% triggers repeat screening. RH right hand, F foot.