A randomised, simulated study assessing auscultation of heart rate at birth

Heart rate is a primary clinical indicator directing newborn resuscitation. The time taken to assess the heart rate by auscultation in relation to accuracy during newborn resuscitation is not known.

To assess both the accuracy and time taken to assess heart rate by stethoscope in simulated resuscitation scenarios.

The VitalSim((c)) manikin (Laerdal Medical, Stavanger, Norway) was used in this randomised, single blind study. Four heart rate settings (0, 40, 80, 120 beats per minute (bpm)) were randomly assigned. Participants assessed them by auscultation in three different scenarios. The first scenario was to assess the actual heart rate at birth. In the second scenario, heart rate was assessed during ventilation and assigned to standard ranges (<60, 60-100, >100bpm). In the third scenario, heart rate was assessed after three cycles of compressions and ventilation and assigned to standard ranges.

In total 61 midwives, nurses and doctors performed 183 assessments. Mean time to estimate heart rate for scenarios 1, 2 and 3 was: 17.0, 9.8 and 7.8s respectively. Heart rate assessments were inaccurate in 31% (scenario 1), 28% (scenarios 2) and 26% (scenario 3). There was a trend for assessors who were accurate to be quicker and this achieved significance in scenario 2 (p<0.02). Inaccurate assessment would have made a difference to management in 28% of all cases.

Mean time to estimate heart rate for the scenarios varied between 7.8 and 17.0s. Twenty-eight percent of all heart rate assessments would have prompted incorrect management during resuscitation or stabilization. Of incorrect assessments, 73% were overestimations. Further research is required to develop a rapid and accurate method for determining heart rate during newborn resuscitation.