Surgical pleth index monitoring in perioperative pain management: usefulness and limitations

Energy Expenditure, a New Tool for Monitoring Surgical Stress in Colorectal Oncological Patients: A Prospective, Monocentric Study

BACKGROUND

Surgical stress response in colorectal surgery consists of a neurohormonal and an immunological response and influences oncological outcomes. The intensity of surgical trauma influences mortality, morbidity, and metastasis' occurrence in colorectal neoplasia. Energy expenditure (EE) stands for the body's energy consumed to keep its homeostasis and can be either calculated or measured by direct or indirect calorimetry.

AIM

The present study attempted to evaluate surgical stress response using EE measurement and compare it to the postoperative cortisol dynamic.

METHODS

A prospective, monocentric study was conducted over a period of one year in the Anesthesiology Department including 21 patients from whom serum cortisol values were collected in the preoperative period and on the first postoperative day, and EE was measured and recorded every 15 minutes throughout surgery using the indirect calorimetry method. The study compared EE values' dynamic registered 30 minutes after intubation and 30 minutes before extubating (after abdominal closure) to cortisol perioperative dynamic.

RESULTS

We enrolled 21 patients and 84 measurements were recorded, 42 probes of serum cortisol and 42 measurements of EE. The mean value of the first measurement of serum cortisol was 13.60±3.6 µg and the second was 16.21±6.52 µg. The average value of the first EE recording was 1273.9±278 kcal and 1463.4±398.2 kcal of the second recording. The bivariate analysis performed showed a good correlation between cortisol variation and EE's variation (Spearman coefficient=0.666, p<0.001, CI=0.285, 0.865). In nine cases (42.85%), cortisol value at 24 hours reached the baseline or below the baselines preoperative value. In eight cases (38.09%), patients' EE at the end of the surgery was lower than that recorded at the beginning of the surgery.

CONCLUSIONS

Intraoperative EE variation correlated well with cortisol perioperative dynamic and stood out in this study as a valuable and accessible predictor of surgical stress in colorectal surgery.

Possibility of Using Surgical Pleth Index in Predicting Postoperative Pain in Patients after Vitrectomy Performed under General Anesthesia

Adequacy of anesthesia concept (AoA) in the guidance of general anesthesia (GA) is based on entropy, and it also reflects the actual depth of anesthesia and the surgical pleth index (SPI). Therefore, this study aimed to analyze the potential existence of relationships between SPI values at certain stages of the AoA-guided GA for vitreoretinal surgeries (VRS) and the incidence of intolerable postoperative pain perception (IPPP). A total of 175 patients were each assigned to one of five groups. In the first, the VRS procedure was performed under GA without premedication; in the second group, patients received metamizole before GA; in the third, patients received acetaminophen before GA; in the fourth group, patients received Alcaine before GA; and, in the peribulbar block group, the patients received a peribulbar block with a mix of the solutions of lignocaine and bupivacaine. Between the patients declaring mild and statistically significant differences in the IPPP in terms of SPI values before induction (52.3 ± 18.8 vs. 63.9 ± 18.1, p < 0.05) and after emergence from GA (51.1 ± 13 vs. 68.1 ± 8.8; p < 0.001), it was observed that the patients postoperatively correlated with heart rate variations despite the group allocation. The current study proves the feasibility that preoperative SPI values help with predicting IPPP immediately after VRS under AoA guidance and discrimination (between mild diagnoses and IPPP when based on postoperative SPI values) as they correlate with heart rate variations. Specifically, this applies when the countermeasures of IPPP and hemodynamic fluctuations are understood to be of importance in reducing unwelcome adverse events.

The Adequacy of Anesthesia Guidance for Vitreoretinal Surgeries with Preemptive Paracetamol/Metamizole

Despite the possibility of postoperative pain occurrence, in some patients, vitreoretinal surgeries (VRSs) require performance of general anesthesia (GA). The administration of intraoperative intravenous rescue opioid analgesics (IROA) during GA constitutes a risk of perioperative adverse events. The Adequacy of Anesthesia (AoA) concept consists of an entropy electroencephalogram to guide the depth of GA and surgical pleth index (SPI) to optimize the titration of IROA. Preemptive analgesia (PA) using cyclooxygenase-3 (COX-3) inhibitors is added to GA to minimize the demand for IROA and reduce postoperative pain. The current analysis evaluated the advantage of PA using COX-3 inhibitors added to GA with AoA-guided administration of IROA on the rate of postoperative pain and hemodynamic stability in patients undergoing VRS. A total of 165 patients undergoing VRS were randomly allocated to receive either GA with AoA-guided IROA administration with intravenous paracetamol/metamizole or with preemptive paracetamol or metamizole. Preemptive paracetamol resulted in a reduction in the IROA requirement; both preemptive metamizole/paracetamol resulted in a reduced rate of postoperative pain as compared to metamizole alone. We recommend using intraoperative AOA-guided IROA administration during VRS to ensure hemodynamic stability alongside PA using both paracetamol/metamizole to reduce postoperative pain.