Background Heart rate (HR) is a vital sign in the assessment of newborn infants. After birth, clinical assessment of HR may be inaccurate and data from pulse oximetry in the delivery room delayed. A digital stethoscope (DS) and mobile technology may offer rapidity and accuracy at a low cost especially in low resource settings.
Aim To determine the accuracy and precision of HR obtained by a DS and smart device application.
Methods Convenience sample of stable infants in the NICU were studied using a Stethocloud™ v2 digital stethoscope with Neorate 0.1a software application, run on an Apple iPhone™ 5S. We measured speed of data acquisition and compared DS HR with 3 lead electrocardiographic (ECG) values at one-second intervals during a 90 second recording using Bland-Altman analysis.
Results We studied 57 infants but excluded seven where either the DS did not capture HR within 30 seconds of activation or returned less than ten paired values. Data from 50 infants,mean (SD) corrected gestational age and weight of 34 (4.4) weeks, 1838 (718) g were analysed. Of these infants 50% were female and 34% were receiving positive pressure respiratory support. The mean (SD) time to HR detection by the application from the standby mode was 5(5) seconds. Figure shows the mean difference (±2SD) between ECG and DS HR was 8(±50) bpm from 3896 paired readings.
Conclusion DS technology to measure infant HR is rapid, promising and accurate but precision should be improved before widespread clinical application.