Heart rate variability of transported critically ill neonates

Abstract

Determining heart rate variability (HRV) in infants is a useful measure of physiological stability. Transport of ill neonates imposes a measurable degree of stress. A prospective observational study on 58 critically ill neonates, transported to an intensive care unit (ICU) was performed. HRV during the 24-h period before, during and after transport, heart rate (HR), mean arterial pressure and transport risk index of physiologic stability (TRIPS) score were observed. The median HRV total power value of 40.80 ms(2) was set as the cutoff value, and neonates with values below this were designated as the low-HRV group (l-HRV; n=29), and those above this as the high-HRV group (h-HRV; n=29). The h-HRV group had a significantly lower HR at retrieval and 1 h after admission and a significant 2- and 4-day shorter duration of mechanical ventilation and ICU treatment compared to the l-HRV group. Spearman's correlations between total power and duration of mechanical ventilation (ρ=-0.346; P<0.01) and ICU treatment (ρ=-0.346; P<0.01) were significant. Transported neonates were also tested for differences in HRV and other physiological and demographic parameters between the transport mode and time. No differences were found, except that the nighttime ambulance group had a statistically higher HRV compared to the daytime ambulance group. Higher HRV of group of neonates, who did not differ in illness severity TRIPS score from the lower HRV group, is associated with a faster and significant decrease in HR after transport and a 2- and 4-day shorter duration of mechanical ventilation and ICU treatment.