Respiratory sinus arrhythmia: comparison with EEG indices during isoflurane anaesthesia at 0.65 and 1.2 MAC

Abstract

Respiratory sinus arrhythmia (RSA) is a cyclical variation in heart rate during breathing, where the heart rate increases during inspiration and decreases during expiration. RSA and the electroencephalogram (EEG) were monitored in 10 patients undergoing elective surgery with isoflurane and nitrous oxide in oxygen anaesthesia after induction with propofol. All patients were subject to controlled ventilation and recovery from competitive neuromuscular block was facilitated by neostigmine and glycopyrronium (seven patients) or atropine (three patients). Median and spectral edge (95%) frequencies of the raw EEG were derived off-line. RSA and EEG indices were obtained during preinduction (baseline), induction, incision, 0.65 and 1.2 MAC of isoflurane maintenance during surgery and recovery. Significant decreases in the level of RSA, median and spectral edge frequencies were observed during induction and significant increases in all indices were observed at recovery in all patients. Significant decreases in the median and spectral edge EEG frequencies occurred in patients treated with atropine both to counteract bradycardia after propofol induction and at antagonism of neuromuscular block (n = 3), compared with patients treated with glycopyrronium (n = 7). In contrast, the level of RSA did not decrease significantly with atropine. It is concluded that measurements of RSA could form the basis of a useful index of anaesthetic depth during isoflurane anaesthesia, even during the use of pharmacologically appropriate doses of atropine. However, any effects of atropine on the raw EEG and on indices derived from the EEG, should be characterized further so that these effects are not confused with changes in anaesthetic depth.

Time‐frequency balanced spectral entropy as a measure of anesthetic drug effect in central nervous system during sevoflurane, propofol, and thiopental anesthesia

“…In individual patients, increase in the RE-SE difference was seen already some minutes before the approaching emergence could be anticipated from SE or BIS. This observation may be related to the findings of early recovery of other brainstem-controlled phenomena, such as the respiratory sinus arrhythmia (15), suggesting that the anesthetic drug effect may cease at the brainstem level Muscles of the upper part of the face are innervated by the 7th cranial nerve, with their function only partly under voluntary control. Electrical activity of the upper facial muscles is of rather high frequency, mostly above 32 Hz (17).…”

Fractal ventilation enhances respiratory sinus arrhythmia

“…Anaesthesia, both type and depth can influence RSA [21,22]. However, the depth of anaesthesia was a controlled variable in our experiment as we employed a continuous infusion of propofol/ketamine with a cross-over design, thereby minimizing time effects.…”

The influence of premedication on heart rate variability

“…Pomfrett et al . [13, 24] reported that respiratory sinus arrhythmia responds promptly to different levels of anaesthesia and recovery, in addition to the degree of surgical stimulation, while the EEG indices responded with some delay; these findings suggest that respiratory sinus arrhythmia may be used as a tool to gauge the depth of anaesthesia according to the surgical needs, and may be a better indicator of MAC than the EEG [25].…”