Congenital heart disease (CHD) is the most common birth defect in newborns, with a global incidence of approximately 9 per 1,000 live births. About one-quarter of these cases are critical congenital heart disease (CCHD). Failure to detect these conditions early can lead to life-threatening complications, making early newborn CHD screening crucial. Pulse oximetry (POX), due to its simplicity, low cost, non-invasive nature, and high efficiency, has become a first-line tool for newborn CHD screening and is included as a routine screening item for newborns in many countries. However, a systematic review and meta-analysis recently published in the Chinese Journal of Evidence-Based Pediatrics clearly indicates that altitude is a key factor affecting the accuracy of pulse oximetry screening. Clinical application requires individualized adjustments based on altitude.

I. Standard Newborn CHD Pulse Oximetry Screening Protocol (Sea Level Applicable)

The standard newborn congenital heart disease pulse oximetry screening protocol established by the American Academy of Pediatrics (AAP) uses a blood oxygen saturation (SpO₂) threshold of <95% for a positive screen. This protocol has been well-validated at sea level:

Screening Sensitivity: 76.3%
Screening Specificity: 99.9%

In low-altitude and sea-level regions, implementing newborn CHD screening according to the AAP standard enables stable and efficient early detection of CHD.

II. Significant Impact of Altitude on Newborn Pulse Oximetry Screening Accuracy

In non-sea-level areas with altitudes >200m, reduced atmospheric pressure and environmental hypoxia directly lead to lower baseline blood oxygen saturation in newborns. Direct application of the AAP standard threshold can result in a substantial increase in false-positive rates.

Research data show: At an altitude of 780m, the false-positive rate for newborn pulse oximetry screening is 3.5 times higher than at sea level.

Excessive false positives not only waste medical resources but also increase parental anxiety, negatively impacting the overall efficiency of newborn CHD screening.

III. Optimized Newborn CHD Pulse Oximetry Screening Protocols for Different Altitude Regions

This meta-analysis incorporated 7 diagnostic accuracy studies from altitudes ranging from 0 to 4338m. Subgroup analysis provides a stratified screening strategy for clinical practice：

Sea Level & Low Altitude: Continued use of the original AAP protocol yields optimal results.
Sensitivity: 79% | Specificity: 99% | AUC: 0.871
This allows for precise and efficient completion of newborn CHD screening.

High Altitude Regions (e.g., 3380m): Adjusted screening protocols are recommended.
- Appropriately modifying the blood oxygen saturation cutoff value, or
- Combining screening with cardiac auscultation
These adjustments can increase sensitivity to 74%, effectively reducing the missed diagnosis rate and achieving the core objective of CHD screening.

Mixed Altitude Regions: Adjusted protocols demonstrate stable performance.
Sensitivity: 61% | Specificity: 96%

IV. Key Points for Clinical Implementation of Newborn Pulse Oximetry Screening

To improve the quality of newborn CHD screening, clinical execution must follow standardized procedures:

  • Implement altitude-stratified screening protocols; avoid uniformly applying sea-level standards.
  • Standardize operation: Screen between 6–72 hours after birth, measuring blood oxygen in the right hand and one foot.
  • Establish a closed-loop management system of "screening – referral – diagnosis."
  • Use echocardiography as the gold standard for confirming positive screening results.

Currently, there is no globally unified normal range for newborn blood oxygen saturation across different altitudes. Future research needs to further establish altitude-specific blood oxygen reference intervals to continuously optimize congenital heart disease screening strategies.

Conclusion

Pulse oximetry is an indispensable tool for early newborn congenital heart disease screening. Only by combining it with regional altitude characteristics and dynamically adjusting screening protocols can its clinical value be maximized, building the first line of defense for newborn heart health.