Tetanic stimulus of the ulnar nerve as a predictor of heart rate response to skin incision in propofol-remifentanil anaesthesia

Nociceptive activation in spinal cord and brain persists during deep general anaesthesia

“…Clinical responsiveness was assessed at each concentration by repeated administration of transcutaneous electrical stimuli to the right ulnar nerve at an intensity comparable with surgical stimulation (30 s tetanic stimulation at 80 mA; NS252, Fisher & Paykel Healthcare Ltd., Auckland, New Zealand). 10 Before, during, and after every stimulus, the heart rate was measured continuously, based on a beat-by-beat analysis of the ECG as integrated in the applied clinical monitoring system (Precess 3160, Invivo, Gainesville, FL, USA). Noxious stimulation was not started before the heart rate was stable (variation of less than 2 beats min À1 ) for at least 1 min.…”

“…Regarding our setup, another limitation might be that we used two different stimulation sites for noxious stimulation: to monitor clinical responsiveness we applied noxious stimuli to the ulnar nerve, as tetanic stimulation to this nerve is a validated and reliable experimental pain model mimicking surgical stimuli. 10 To monitor spinal and brain activation we applied noxious and innocuous stimuli to the sural nerve, as this stimulation site allowed us to monitor spinal nociceptive activation through quantification of the nociceptive flexion reflex amplitude. Therefore, our results might be biased as a result of differences in stimulation intensity between the two sites, even though the intensity at both stimulation sites was adjusted to be comparable with the intensity of surgical stimuli, based on the half maximal effective concentrations and minimum alveolar concentration values associated with these stimuli.…”

Measurement of surgical stress in anaesthetized children

“…18 (A 30 s tetanic stimulation has been demonstrated to be comparable with stress from skin incision.) 22 Increasing predicted effect-site concentration of propofol from 5.3 to 6.9 mg ml 21 had minimal impact on SSI (DSSI decreased only from 32 to 25). 18 Furthermore, SSI identified tetanic stimuli more accurately compared with SE, RE, HR, or PPGA.…”

Correlation between incremental remifentanil doses and the Nociception Level (NOL) index response after intraoperative noxious stimuli

“…This type of noxious stimulation was used in other studies without any reported side effects. 32 Once the observation period ended after this first electrical stimulus (after three minutes), the epidural catheter was bolused with 3 mL of lidocaine 2% with epinephrine (AstraZeneca Inc, Mississauga, ON, Canada) in preparation for the incision. Approximately five minutes after this first epidural dose, and under a continuous remifentanil infusion at 0.05 lg kg -1 min -1 , the incision for laparotomy was performed, and all data were recorded electronically for a three-minute period.…”