Development of a Hemodynamic Model Using Routine Monitoring Parameters for Nociceptive Responses Evaluation During Surgery Under General Anesthesia

Abstract

BackgroundRoutine hemodynamic monitoring parameters under general anesthesia, such as heart rate (HR), systolic blood pressure (SBP), and perfusion index (PI), do not solely reflect intraoperative nociceptive levels. We developed a hemodynamic model combining these 3 parameters for nociceptive responses during general anesthesia, and evaluated nociceptive responses to surgical skin incision.Material/MethodsWe first retrospectively performed discriminant analysis using 3 values – HR, SBP, and PI – to assess response to skin incision during tympanoplasty, laparoscopic cholecystectomy, and open gastrectomy to determine if combined use of these parameters differentiates nociceptive levels among these 3 surgeries. Secondly, ordinal logistic regression analysis was applied using the 3 parameters to develop an equation representing nociceptive response during general anesthesia, and then evaluated its utility to discern nociceptive responses to skin incision.ResultsWe developed the following hemodynamic model as calculated nociceptive response= −1+2/(1+ exp(−0.01 HR −0.02 SBP +0.17 PI)), and prospectively determined that calculated nociceptive responses to small skin incision for laparoscopic surgery were significantly lower than responses to large skin incision for laparotomy.ConclusionsOur hemodynamic model using HR, SBP, and PI likely reflects nociceptive levels at skin incision during general anesthesia, and quantitatively discerned the difference in nociceptive responses to skin incision between laparoscopy and laparotomy. This model could be applicable to assess either real-time nociceptive responses or averaged nociceptive responses throughout surgery without using special equipment.

Associations between intraoperative nociceptive and early postoperative C-reactive protein levels in patients undergoing non-cardiac surgery under general anesthesia

“…Although either longer duration of surgery or obesity has been reported to be a risk factor for postoperative complications [18-21], intraoperative nociceptive level has not been evaluated. The degree of inflammation or tissue damage caused by surgical trauma affects both the intraoperative nociceptive level [13] and postoperative CRP level [9]. Given that minimizing surgical trauma by performing laparoscopy instead of open surgery reportedly reduces early postoperative CRP levels [22][23][24], it seems plausible that the mean NR value for possible estimation of the intraoperative nociceptive level was selected as one of intraoperative factors for the prediction of early postoperative CRP level in the present study.…”

“…At the time of skin incision, it increases again, then keeping around 0.7-0.9 during surgery. The NR value was calculated using the following hemodynamic equation: NR = -1 + 2 / (1 + exp (-0.01HR -0.02SBP + 0.17PI)) [13]. NR value represents no nociceptive stimulus under 0.70, minor noxious stimulus like very small incision between 0.70 and 0.75, moderate noxious stimulus like laparoscopic surgery between 0.75 and 0.85, severe noxious stimulus like open abdominal surgery between 0.85and 0.90, and extreme noxious stimulus over 0.90.…”

“…The analgesia nociception index (ANI) is calculated from heart rate variability [11], and the surgical pleth index (SPI) is calculated using photoplethysmographic pulse wave amplitude and heart beat interval [12]. Recently, we developed the nociceptive response (NR) for the evaluation of nociceptive levels under general anesthesia, which is calculated using the variables of heart rate, systolic blood pressure, and perfusion index [13].…”

“…Given that nociceptive indices likely correspond to the intensity of inflammation or tissue damage during surgery under general anesthesia [13], we considered that an averaged value of the NR throughout surgery under general anesthesia represent the intraoperative nociceptive level in each surgery.…”

Mathematical evaluation of responses to surgical stimuli under general anesthesia

“…Based on the notion that assessment of multiple physiological parameters of autonomic responses (e.g., heart rate variability, skin conductance, photoplethysmography, blood pressure, heart rate, perfusion index, etc.) would better reflect the complex nature of pain intensity and intraoperative nociception than any individual parameter alone 7 , several methods to monitor nociceptive levels have been developed 7 – 11 . The association between S and R calculated with these indices of nociception monitoring under general anesthesia, however, has not been well evaluated.…”