Threshold to initiate chest compressions for bradycardia at birth: A narrative review

Neonatal resuscitation guidelines recommend initiating chest compressions (CC) in newborns at birth if heart rate (HR) remains <60 bpm after 30 s of ventilation. This threshold is based on expert opinion and scant animal data. Our aim was to systematically evaluate the existing evidence and appraise current insights regarding thresholds for starting CC during bradycardia at birth. A recent scoping review synthesized the evidence on various aspects of neonatal CC until November 2021. We updated this review, focusing on HR thresholds for CC, with a new systematic literature search in MEDLINE, Embase, and the Cochrane Database of Systematic Reviews until March 2024. No studies comparing HR thresholds for CC commencement at birth were identified. Consequently, we decided to review the literature more narratively, covering a wider range of topics within this subject matter. Relevant papers from the initial search were used and additional sources of information were sought using snowballing procedures. Numerous publications were identified, containing pathophysiological considerations, in vitro experiments, animal data, and some human data. Preliminary findings from a recent mathematical model study conducted in our center were also briefly considered. All this information enabled a thorough discussion on the rationale for CC during neonatal bradycardia. Finally, a survey was disseminated among knowledgeable neonatal clinicians and researchers to evaluate their perspectives on initiating CC for neonatal bradycardia. Of 183 survey respondents, 137 (74.9%) indicated they would wait longer than the currently recommended 30 s of assisted ventilation before starting CC in newborns with a HR (rising) between 30 and 60 bpm, acknowledging effective ventilation as a priority. We conclude that clinical evidence is lacking, though reconsideration of the threshold to initiate CC for bradycardia at birth seems justified based on available data. This is supported by the views of many surveyed professionals. Randomized trials in human infants and appropriate newborn animal models are warranted.