Abstract

Parasympathetic tone activity (PTA) is an index based on the parasympathetic tone through heart rate variability analysis that has been recently developed to assess the analgesia/nociception balance during anaesthesia.² This index has first been used in human medicine, known as the ANI index (Analgesia Nociception Index) and has shown good performance in predicting haemodynamic responses (HDR) associated with intraoperative nociceptive stimuli in anaesthetized patients.¹ Few studies have evaluated the performance of PTA in domestic animals, but results were promising.³

In this study, reliability and performance of the PTA index to predict HDR was evaluated following nociceptive stimulus (subcutaneous saline injection, surgical skin incision or ear tagging) in several anesthetized zoo species (9 lemurs: Lemur catta, Eulemur rubriventer, Eulemur coronatus, Eulemur macaco, 12 Axis porcinus, 6 Cervus nippon nippon, and 6 Capra falconeri heptneri). Animals were anesthetized either with an intramuscular combination of an α2 agonist, xylazine or medetomidine, and ketamine or with isoflurane. At 2 or 3 times of interest (T1 steady state, T2 stimulation, or T3 end of procedure) the following parameters were measured and taken on a set schedule for each animal before, 1 min, 3 min, and 5 min after each T: PTA, heart rate, and systolic blood pressure. Then HDR and ∆PTA were calculated.

No significant correlation (Friedman test and Dunn test) has been shown between PTA index and HDR in the species tested undergoing anaesthesia. An explanation could be based on the analgesic effect of the drugs used (for example α2 agonist) and the small samples selected. To the authors‘ knowledge, PTA has never been tested on non-domestic species and further studies are needed to confirm these preliminary results.

Acknowledgments

The authors would like to thank the team of Mdoloris Medical System: Jean-Yves Nadaud, Paul Spanneut and Idir Ibarissene.

Literature Cited

1.  Boselli E, Logier R, Bouvet L, Allaouchiche B. Prediction of hemodynamic reactivity using dynamic variations of analgesia/nociception index (DANI). J Clin Monit Comput. 2016;30(6):977–984.

2.  Jeanne M, Logier R, De Jonckheere J, Tavernier B. Validation of a graphic measurement of heart rate variability to assess analgesia/nociception balance during general anesthesia. In: Conf Proc IEEE Eng Med Biol Soc; 2009:1840–1843.

3.  Mansour C, Merlin T, Bonnet-Garin JM, Chaaya R, Mocci R, Ruiz CC, Allaouchiche B, Boselli E, Junot S. Evaluation of the parasympathetic tone activity (PTA) index to assess the analgesia/nociception balance in anaesthetised dogs. Res Vet Sci. 2017;115:271–277.