Experimental study on the effects of isoflurane with and without remifentanil or dexmedetomidine on heart rate variability before and after nociceptive stimulation at different MAC multiples in cats

Abstract

Background Heart rate variability (HRV) provides information about autonomic nervous system (ANS) activity and is therefore a possible tool with which to assess anaesthetic depth. The aim of the present study was to evaluate the effects of isoflurane, remifentanil and dexmedetomidine on HRV before and after nociceptive stimulation at different anaesthetic depths. Seven healthy domestic short-hair cats were used, and each cat was anaesthetized three times – group I with isoflurane alone, group IR with isoflurane and a constant rate infusion (CRI) of remifentanil (18 μg/kg/h), and group ID with isoflurane and a CRI of dexmedetomidine (3 μg/kg/h). Minimum alveolar concentration (MAC) values were determined via electrical supramaximal nociceptive stimulation for each treatment group. Nociceptive stimulation was repeated at 3 different MAC multiples (0.75, 1.0 and 1.5 MAC), and electrocardiographic recordings were performed for 3 min before and after stimulation. Only the 1 min epochs were used for further statistical analysis. Electrocardiographic data were exported for offline HRV analysis. Results The mean isoflurane MAC ± standard deviation (SD) was 1.83 ± 0.22 vol% in group I, 1.65 ± 0.13 vol% in group IR and 0.82 ± 0.20 vol% in group ID. Nociception was indicated by several HRV parameters, however, with high variability between treatments. The best correlation with MAC was found for the SD of heart rate (STD HR) in group I ( r s = − 0.76, p = 0.0001, r 2 = 0.46). STD HR was also able to distinguish 0.75 MAC from 1.5 MAC and 1.0 MAC from 1.5 MAC in group I, as well as 0.75 MAC from 1.5 MAC in group ID. Conclusions The choice of anaesthetic protocol influences the HRV parameters in cats. Frequency domain parameters respond to nociception at lower MAC levels. The STD HR has the potential to provide additional information for the assessment of anaesthetic depth in isoflurane-anaesthetized cats. The utility of HRV analysis for the assessment of anaesthetic depth in cats is still questionable. Electronic supplementary material The online version of this article (10.1186/s12917-019-2004-8) contains supplementary material, which is available to authorized users.

Effects of ivabradine and atenolol on heart rate and heart rate variability in healthy cats over a 24 h period: A pilot study

“…However, SDNN, RMSSD, pNN50 and LF, which are used to quantify vagal activity, were also elevated, suggesting that HF was elevated due to the increased vagal activity rather than blood pressure variation. 27,31 In the present study, HRV was also decreased during excitement, which may have been due to increased sympathetic activity in the cats, as mentioned earlier. The HRV parameters for the BL and after ivabradine and atenolol therapy, were not significantly different at feeding time, whereas the most significant differences were observed at the sleeping time when the sympathetic activity tended to decrease.…”

“…23 The HF parameter is used as an indicator of vagal nerve activity and LF is used to indicate sympathetic and vagal nerve activity. 31,32 Thus, these indicate an increase in sympathetic nerve activity and/or a decrease in vagal nerve activity. The significant decrease in the LF/HF may reflect an increase in sympathetic nerves activity and a decrease in vagal nerves activity during the feeding time compared with BL.…”

“…SDNN and RMSSD are used as indicators of the degree of HRV, while pNN50 indicates vagal nerve activity 23 . The HF parameter is used as an indicator of vagal nerve activity and LF is used to indicate sympathetic and vagal nerve activity 31,32 . Thus, these indicate an increase in sympathetic nerve activity and/or a decrease in vagal nerve activity.…”

Comparative Study of Pain-Related Responses of Male Piglets up to Seven Days of Age to the Application of Different Local Anaesthetics and Subsequent Castration

“…Radeisen [ 31 ] also could relate changes in frequency domain indices to intraoperative pain associated nocifensive movements during castration of boars in the pubic region, especially during incision of the skin and the vaginal process and during the traction of the spermatic cord, whereby time domain HRV did not reflect those single pain events. Using the LF/HF ratio Raue et al [ 66 ] could detect nociceptive stimulation in cats in only 60 s post stimulation epoch measurements, while longer time periods revealed a readjustment to the basal values. Generally, short-term measures of HRV rapidly return to baseline after transient disturbances [ 28 ], therefore the recording time has a significant influence especially on time domain values [ 30 ] and a rapid recovery of the heart rate after the injection might be the reason for the rise in SDHR and SDRR.…”

Effects of isoflurane, remifentanil and dexmedetomidine on selected EEG parameters derived from a Narcotrend Monitor before and after nociceptive stimulation at different MAC multiples in cats

“…Additionally, for another part of the study [45], four ECG surface electrodes were placed palmar and plantar on the paws, or, if the signal was too low, laterally on both sides of the chest.…”