Investigators considered whether monitoring heart rate characteristics (HRC) adds information to conventional laboratory tests in the diagnosis of neonatal sepsis-a hypothesis based on the observation that newborns have reduced heart rate variability and transient decelerations before clinical signs of sepsis appear. Investigators developed a predictive HRC monitoring strategy based on those observations. The resulting HRC values are called the HRC index, with values above the 90th percentile representing high risk of neonatal sepsis and values between the 70th and 90th percentiles representing intermediate risk.
The study was performed in 678 infants who spent more than seven days in the neonatal intensive care unit and of whom 29% had one or more episodes of sepsis. HRC values were available for 137 of 149 episodes of sepsis confirmed by blood culture. The HRC index correlated highly with sepsis. In addition, investigators confirmed the association of the ratio of immature to total neutrophil count, abnormal white blood cell count, hyperglycemia, and low pH with neonatal sepsis. Their conclusion? HRC monitoring adds independent information to laboratory tests in the diagnosis of culture-positive neonatal sepsis (Griffin MP et al: Pediatrics 2005;115:937).
CommentaryNeonatologists and other pediatricians continue to search for this Holy Grail: an accurate early sign of neonatal sepsis. Heart rate characteristics, available through analysis of continuous cardiac monitoring, may turn out to be at least part of what we've been looking for.