POX Range and the Threshold for Screening Major CHD in Neonates at Different Altitudes

Study on the Normal Range of Pulse Oximetry and the Threshold for Screening Critical Congenital Heart Disease in Neonates at Different Altitudes in China

major CHD (Congenital Heart Disease) screening by POX (pulse oximetry) in sea-level areas is not fit for low, medium and high altitude areas, but the normal range of pulse oximetry at different altitude areas has not been studied before, so the current screening technology can only be used in sea-level areas, but not for newborns in low, medium and high altitude areas. We need to carry out a research to clarify the range of POX and make sure the threshold of POX in major CHD screening in different altitude areas of China.

At present, the application of POX (pulse oximetry) in screening major CHD (congenital heart disease ) has been legislated in the United States. In China, the two indicators of POX plus auscultation of heart murmur for screening major CHD have also been promoted as national standards. There are differences in the POX range of newborns at different altitude areas, so the threshold of POX screening based on sea-level areas is not applicable to low, medium and high altitude areas. While the normal range of POX at different altitude areas has not been studied in detail, so the current screening strategy can only be used in sea-level areas, but not benefit newborns in low, medium and high altitude areas. In order to apply major CHD screening strategy better to cover the newborns all over the country, we need to clarify the range of POX at different altitude areas of China and make sure the threshold of POX in major CHD screening. We plan to carry out a multicenter study on the normal POX value range of healthy and asymptomatic term newborns 6-72 hours after delivery in medical centers with altitude of 500-1000; 1000-2000; 2000-3000; 3000-4000 and above 4000 meters. And compare the POX value at different altitude areas with that of newborns delivered in the maternity hospitals at sea level. And measure the POX value of newborns with major CHD in the same way. POX screening thresholds will be obtained at different altitude areas. We will test the hypothesis that POX of healthy newborns at different altitude areas is lower than that of healthy newborns at sea level, and POX threshold of major CHD screening is lower than that of sea level.

Inclusion Criteria:

For healthy newborns:

• Healthy, asymptomatic, singleton term infants (37-41 weeks gestation);
• Appropriate for gestational age (using the international WHO's intrauterine growth curve to evaluate);
• Only newborns with Apgar score ≥ 7 in 1 minute and 5 minutes were selected;
• There is no known congenital heart disease based on the ECHO result , no murmur, no obvious signs (no fever, no tachycardia or respiratory symptoms at the time of admission).

For major CHD newborns:

• Echocardiography clearly diagnosed the following congenital heart diseases: Aortic stenosis, Double outlet of right ventricle, Ebstein's malformation, Left cardiac hypoplasia syndrome, Aortic arch disconnection, Pulmonary atresia, Single ventricle, Tetralogy of Fallot, Complete anomalous pulmonary venous drainage, Transposition of great arteries, Tricuspid valve atresia, and Single trunk of arteries and other major CHD based on Ewer's denition.

Exclusion Criteria:

For healthy newborns:

• Newborn with caesarean section; newborn with smoking mother; newborn with definite congenital heart disease before discharge.

For major CHD newborns:

• There is no exclusion criteria for major CHD.