Work

Defining hypoxaemia from pulse oximeter measurements of oxygen saturation in well children at low altitude in Bangladesh: an observational study

Year: 2021

Type: article

Abstract: Background The World Health Organization defines hypoxemia, a low peripheral oxyhemoglobin saturation (SpO 2 ), as <90%. Although hypoxemia is an important risk factor for mortality of children with respiratory infections, the optimal SpO 2 threshold for defining hypoxemia is uncertain in low-income and middle-income countries (LMICs). We derived a SpO 2 threshold for hypoxemia from well children in Bangladesh residing at low altitude. Methods We prospectively enrolled well, 3-35 month old children participating in a pneumococcal vaccine evaluation in Sylhet district, Bangladesh between June and August 2017. Trained health workers conducting community surveillance measured the SpO 2 of children using a Masimo Rad-5® pulse oximeter with a wrap sensor. We used standard summary statistics to evaluate the SpO 2 distribution, including whether the distribution differed by age or sex. We considered the 2.5 th , 5 th , and 10 th percentiles of SpO 2 as possible lower thresholds for hypoxemia. Results Our primary analytical sample included 1,470 children (mean age 18.6 +/- 9.5 months). Median SpO 2 was 98% (interquartile range, 96–99%), and the 2.5 th , 5 th , and 10 th percentile SpO 2 was 91%, 92%, and 94%. No child had a SpO 2 <90%. Children 3– 11 months old had a lower median SpO2 (97%) than 12–23 month olds (98%) and 24– 35 month olds (98%) (p=0.039). The SpO 2 distribution did not differ by sex (p=0.959). Conclusion A SpO 2 threshold for hypoxemia derived from the 2.5 th , 5 th , or 10 th percentile of well children is higher than <90%. If a higher threshold than <90% is adopted into LMIC care algorithms then decision-making using SpO 2 must also consider the child’s clinical status to minimize misclassification of well children as hypoxemic. Younger children in lower altitude LMICs may require a different threshold for hypoxemia than older children. Evaluating the mortality risk of sick children using higher SpO 2 thresholds for hypoxemia is a key next step. Key Messages What is the key question? The ideal peripheral oxyhemoglobin saturation (SpO 2 ) threshold for defining hypoxemia among children in low-income and middle-income countries is unknown. What is the bottom line? A SpO 2 threshold for hypoxemia set at any of the 2.5 th , 5 th , or 10 th percentiles of SpO 2 measurements from well children in a lower altitude setting is higher than the <90% threshold currently recommended by the World Health Organization. Why read on? This study is a possible model for other research seeking to establish SpO 2 thresholds for hypoxemia in children and provides evidence for health policy makers to consider before implementing higher SpO 2 thresholds than currently in practice in lower altitude settings of low-income and middle-income countries.

Source: BMJ Open Respiratory Research

DOI: 10.1136/bmjresp-2021-001023