Pain sensation is characterized by abrupt changes in central nervous system activity producing autonomic reactivity. While clinical hypnosis has demonstrated its benefits for children in pain management, it is not clear whether hypnosis modulated autonomic pain response in children in clinical conditions. Here, we studied autonomic responses under hypnosis to sutures in pediatric emergencies. For that, 42 children (mean age: 6.5 years, range 1.5 to 13) were divided into two groups consecutively (hypnosis and control groups), according to their choice. Time-frequency analysis was applied on RR intervals (heart rate interbeat intervals, or RRI) to estimate parasympathetic reactivity based on high frequency power (HF) and the Analgesia Nociception Index (ANI®) and on sympathetic reactivity (low frequency power [LF]) and LF/HF ratio). We observed that RRI and LF/HF ratio varied according to suture and hypnosis (p < 0.05): RRI was higher and LF/HF ratio was lower during sutures in the hypnosis group in comparison to the control group whereas HF and ANI® increased only during hypnosis. To conclude, hypnosis in pediatric emergencies reduces sympathetic cardiac pain reactivity and could be a marker of pain relief under hypnosis, while parasympathetic activity seems to be a better marker of hypnosis.
Keywords: Analgesia and Nociception Index®; Autonomic nervous system; Pain; RRI variability; Suture.