|M.Sc Student||Aranovitch Michal|
|Subject||Cardiac Autonomic Reactivity and Behavioral Response to Pain|
in Full-Term Neonates
|Department||Department of Medicine||Supervisor||Clinical Professor Etan Zimmer|
|Full Thesis text - in Hebrew|
Purpose: The purposes of this study were: to compare the analgesic effect of several behavioral methods during the heel lancing procedure in term new-born infants; to assess relations and concordance between behavioral and autonomic cardiac reactivity to pain; to assess the efficacy of spectral analysis of HRV as a physiologic method for evaluating cardiac autonomic reactivity and pain assessment in term neonates.
Design: Open prospective study.
Setting: Rambam Medical Center.
Participants: 180 term newborn infants at age 2-3 days were exposed to the painful intervention of routine heel blood sampling for phenylketonuria and hypothyroidism screening.
Interventions: Participants were assigned to 6 groups, 30 infants in each group:
1) control group (infants in crib without any pain relief intervention), 2) non-nutrition sucking group (pacifier sucking), 3) holding group (infants held by their mother), 4) glucose group (2 cc of 30% glucose solution per os, 2 minutes before the painful intervention), 5) materna group (feeding with the "Materna" formula), 6) breastfeeding group (infants breastfed by their mothers).
Outcome measures: Behavioral pain measures included behavioral face expression score of the NFCS (Neonatal Facial Coding System) scale, and cry duration (in seconds).
Autonomic pain measures consisted of heart rate changes and spectral analysis of heart rate variability. Heart rate variability variables were quantified using the area (power) of spectrum in an LF (low frequency) region (0.04-0.15 Hz), HF (high frequency) region (0.15-0.8 Hz), and by the LF/HF ratio.
Results: Infants who were breastfed or received the "Materna" formula during the painful intervention expressed the lowest increase in heart rate and the lowest decrease in the frequency variables compared to other groups (p<0.001).
In addition, the measures of NFCS scoring and cry duration in the feeding groups were significantly lower compared to the control, glucose, holding and sucking groups.
Changes in heart rate correlated positively with cry duration and NFCS score (r=0.341 and r=0.387). Low frequency variable (LF) correlated negatively with cry duration and NFCS score (r=-0.295 and r=-0.325). LF/HF ratio correlated negatively with cry duration and NFCS score (r=-0.231 and r=-0.301).
Conclusions: Feeding during the painful intervention was found to be the most effective behavioral method for pain relief. A significant correlation was noted between infant's behavior and measures of autonomic cardiac activity. Spectral analysis of heart rate variability can therefore be regarded as an objective and non-invasive method for assessment of newborns pain.