Is pulse oximetry helpful for the early detection of critical congenital heart disease at high altitude?

Objective: To assess the pulse oximetry as a method for screening critical congenital heart disease (CHD) in newborns.

Study Design: This is an observational, transversal, descriptive simple study. The pre-ductal and postductal saturation were taken in term newborns that fulfilled the criteria of inclusion and exclusion in the Hospital Gineco-Obstetrico Isidro Ayora (HGOIA) in Quito. These measurements were performed between the 24 and 48 h after birth. Those newborns that saturated less than 90% on initial pulse oxìmetry underwent 3 successive measurements at 1-h intervals. Those who saturate less than 90% after 3 measurements or have a difference higher than 3% in preductal saturation and postductal saturation (positive screening) underwent transthoracic echocardiography evaluate for CHD.

Results: Pulse oximetry from 963 newborns was evaluated. In Quito, at an altitude of 2820 meters above sea level (9252 feet), the mean preductal saturation was 92.76% (SD ± 3) and the postductal saturation, 93.76% (SD ± 4.7). Pulse oximetry in 53 patients (5.5%) was classified as a positive screening. No critical congenital heart diseases were found. Atrial septal defect (ASD) was the most common finding in a 46.94% (n = 23), followed by the association of patent ductus arteriosus (PDA) and ASD with a 12.24% (n = 6).

Conclusion: In this cohort of patients who underwent screening pulse oximetry, no critical congenital heart diseases (CHD) were observed. However, identifying those with oxygen saturation less than 90% after 3 successive measurements or a pre- and postductal oxygen difference of > 3% resulted in successful identification of ASD and PDA. It is necessary to implement new cutoff points in saturation values to identify critical cardiac anomalies in cities placed at a high altitude. The use of pulse oximetry should be recommended in all the newborns.