Effects of hypnosis on the relative parasympathetic tone assessed by ANI (Analgesia/Nociception Index) in healthy volunteers: a prospective observational study

Abstract

Hypnosis has shown an effect on the regulation of the autonomic nervous system by increasing parasympathetic activity. The Analgesia/Nociception Index (ANI) is derived from heart rate variability and represents the relative parasympathetic tone. We investigated the effects of hypnosis on ANI in healthy volunteers. Participants to the 2016 International Hypnosis congress, Saint Malo, France were recruited in this prospective observational study. After comfortable positioning of the subject in the sitting position (T0), the hypnotic trance was induced (T1) then conducted with suggestions of comfort (T2) before return to normal consciousness (T3). The ANI, heart rate (HR) and respiratory rate (RR) were recorded at the different time-points. Forty subjects were enrolled (31 women, 9 men). The mean ± SD ANI at T2 (84 ± 12) was significantly greater than at T0 (60 ± 10), T1 (62 ± 9) and T3 (59 ± 11). The median [25th-75th percentile] ANI values at T2 were significantly greater in women (90 [83-95]) than in men (74 [68-83]). There were no significant variations of HR during time. The median [25th-75th percentile] RR at T1 (16 [14-18] breaths/min) and T2 (14 [12-16] breaths/min) were significantly smaller than at T0 (18 [16-20] breaths/min) and T3 (18 [16-20] breaths/min). This study shows that hypnosis induces an increase in the relative parasympathetic tone assessed by ANI in healthy volunteers, with greater ANI values observed in women. These results suggest that ANI monitoring may provide an objective tool for the measurement of the intensity of the hypnotic process, although this should be confirmed by further studies.

Conscious sedation for the management of dental anxiety in third molar extraction surgery: a systematic review

“…few days before surgery, during the preoperative visit), before-sedation and after-sedation (but before local anesthetic injection) because postoperative assessments are associated with a spontaneous anxiety reduction [33]. In addition, intra-operative data regarding not only standard physiological parameters (such as heart rate, blood pressure, peripheral capillary oxygen saturation) but also less used ones (such as the relative parasympathetic tone assessed by Analgesia/Nociception Index (ANI) should be collected to evaluate the overall patient's perception of the surgical experience [34,35].…”

ANI and BIS variations in supine and prone position during closed-tracheal suction in sedated and myorelaxed ICU patients with severe COVID-19: A retrospective study

“…ANI has been widely studied during general anesthesia or in awake patients [4,[6][7][8][9][10]. It provides an estimate of the relative parasympathetic tone, varying from 0 (no parasympathetic tone, corresponding to maximal sympathetic activity) to 100 (maximal parasympathetic activity corresponding to no sympathetic tone).…”

Conscious sedation for the management of dental anxiety in third molar extraction surgery: a systematic review.

“…few days before surgery, during the pre-operative visit), before-sedation and after-sedation (but before local anesthetic injection) because postoperative assessments are associated with a spontaneous anxiety reduction [33]. In addition, intra-operative data regarding not only standard physiological parameters (such as heart rate, blood pressure, peripheral capillary oxygen saturation) but also less used ones (such as the relative parasympathetic tone assessed by Analgesia/Nociception Index (ANI) should be collected to evaluate the overall patient's perception of the surgical experience [34,35].…”