Effect of preemptive ketamine administration on postoperative visceral pain after gynecological laparoscopic surgery

The ED50 and ED95 of esketamine for preventing early postoperative pain in patients undergoing laparoscopic cholecystectomy: a prospective, double-blinded trial

BACKGROUND

This study aims to estimate the safety, efficacy, and median effective dose (ED50) of esketamine for preventing early postoperative pain in patients undergoing laparoscopic cholecystectomy.

METHODS

54 patients undergoing laparoscopic cholecystectomy were prospectively randomized into two groups (group C and group E). Different doses of esketamine were intravenously administered before the skin incision in Group E. The patients in group C received the same dose of saline at the same time. General population characteristics were recorded. The median effective dose (ED50) and 95% effective dose (ED95) were calculated using Dixon's up-and-down method. Hemodynamic parameters were monitored, and pain intensity was assessed using a visual analog scale. We also recorded the condition of anesthesia recovery period and postoperative adverse reactions.

RESULTS

The ED50 of esketamine for preventing early postoperative pain was 0.301 mg/kg (95%CI: 0.265-0.342 mg/kg), and the ED95 was 0.379 mg/kg (95%CI: 0.340-0.618 mg/kg), calculated by probability unit regression. Heart rate (HR) was significantly lower in the esketamine group compared to the control at the skin incision (p < 0.05). The total VAS score at resting was significantly lower in the esketamine group compared to the control group during the awakening period (p < 0.05). There was no significant difference between the two groups regarding the incidence of adverse reactions (p > 0.05).

CONCLUSIONS

In this study, esketamine can prevent early postoperative pain effectively. The ED50 and ED95 of esketamine for controlling early postoperative pain were 0.301 mg/kg and 0.379 mg/kg, respectively.

TRIAL REGISTRATION

ChiCTR2200066663, 13/12/2022.

Analgesia for Gynecologic Oncologic Surgeries: A Narrative Review

PURPOSE OF REVIEW

Gynecologic oncologic malignancies are amongst the most common cancers affecting women across the world. This narrative review focuses on the current state of evidence around optimal perioperative pain management of patients undergoing surgeries for gynecologic malignancies with a specific focus on cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC).

RECENT FINDINGS

Recent improvements in postoperative pain management following all types of gynecologic procedures, including minimally invasive, open-abdominal, or CRS + HIPEC, have been implemented through enhanced recovery after surgery (ERAS) protocols. These protocols encompass the use of preemptive analgesia, neuraxial and regional techniques, local anesthetic infiltration, and multimodal analgesia. The severity of postoperative pain varies for minimally invasive cancer surgery to open debulking procedures. Therefore, an individualized perioperative analgesic plan is critical depending on the surgical approach. For CRS + HIPEC, neuraxial techniques such as thoracic epidurals and opioid sparing multimodal analgesics have shown efficacy in the perioperative period. However, future research is needed as many of these patients develop chronic pain with very limited research done in this realm.

The Median Effective Dose of One Intravenous Bolus of Oxycodone for Postoperative Analgesia After Myomectomy and Hysterectomy With Local Ropivacaine Wound Infiltration: An Up-Down Dose-Finding Study

BACKGROUND

Oxycodone has been shown to be an effective analgesic for early postoperative analgesia, especially for abdominal operations associated with severe visceral pain. However, the dose needed varies depending on the operation and application of multimodal analgesia, such as local ropivacaine wound infiltration. Therefore, we conducted this study to estimate the median effective dose (ED50) of oxycodone that provides analgesia for hysterectomy and myomectomy with local ropivacaine wound infiltration.

METHODS

In this dose-finding study, the ED50 of oxycodone for postoperative analgesia was estimated separately for laparoscopic hysterectomy, transabdominal hysterectomy, laparoscopic myomectomy, and transabdominal myomectomy. We used the sequential allocation designed by Dixon. Trials were conducted simultaneously in the 4 surgical type groups. A predefined dose of oxycodone was injected 30 minutes before the end of the operation with an initial dose of 0.1 mg/kg. A series of trials were performed following the rule of a relative 10% increase in dose after inadequate analgesia and a relative 10% decrease in dose after adequate analgesia. The study was conducted until the collection of 7 crossover points was achieved. Local ropivacaine wound infiltration was administered during abdominal stitching. The mean blood pressure (MBP) and heart rate (HR) were analyzed to assess the hemodynamic changes associated with oxycodone administration.

RESULTS

A total of 113 patients were included in the estimation of ED50: 28 each in the laparoscopic hysterectomy group and transabdominal myomectomy group, 27 in the transabdominal hysterectomy group, and 30 in the laparoscopic myomectomy group. The estimated oxycodone ED50 (95% confidence interval [CI]) after laparoscopic hysterectomy, transabdominal hysterectomy, laparoscopic myomectomy, and transabdominal myomectomy was 0.060 mg/kg (0.053-0.068), 0.079 mg/kg (0.072-0.086), 0.060 mg/kg (0.051-0.071), and 0.092 mg/kg (0.086-0.098), respectively, for postoperative analgesia with local ropivacaine wound infiltration. The ED50 of oxycodone was different between laparoscopic surgeries and transabdominal surgeries (P < .001). The MBP and HR before and after oxycodone injection were different, regardless of surgical type.

CONCLUSIONS

The oxycodone ED50 for postoperative analgesia was lower for laparoscopic hysterectomy (0.060 mg/kg) and laparoscopic myomectomy (0.060 mg/kg) than for transabdominal hysterectomy (0.079 mg/kg) and transabdominal myomectomy (0.092 mg/kg) when combined with local ropivacaine wound infiltration. A single intravenous injection of oxycodone is associated with an acceptable decrease in MBP and HR within a short time.

Perioperative intravenous ketamine for acute postoperative pain in adults

BACKGROUND

Inadequate pain management after surgery increases the risk of postoperative complications and may predispose for chronic postsurgical pain. Perioperative ketamine may enhance conventional analgesics in the acute postoperative setting.

OBJECTIVES

To evaluate the efficacy and safety of perioperative intravenous ketamine in adult patients when used for the treatment or prevention of acute pain following general anaesthesia.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to July 2018 and three trials registers (metaRegister of controlled trials, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP)) together with reference checking, citation searching and contact with study authors to identify additional studies.

SELECTION CRITERIA

We sought randomised, double-blind, controlled trials of adults undergoing surgery under general anaesthesia and being treated with perioperative intravenous ketamine. Studies compared ketamine with placebo, or compared ketamine plus a basic analgesic, such as morphine or non-steroidal anti-inflammatory drug (NSAID), with a basic analgesic alone.

DATA COLLECTION AND ANALYSIS

Two review authors searched for studies, extracted efficacy and adverse event data, examined issues of study quality and potential bias, and performed analyses. Primary outcomes were opioid consumption and pain intensity at rest and during movement at 24 and 48 hours postoperatively. Secondary outcomes were time to first analgesic request, assessment of postoperative hyperalgesia, central nervous system (CNS) adverse effects, and postoperative nausea and vomiting. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included 130 studies with 8341 participants. Ketamine was given to 4588 participants and 3753 participants served as controls. Types of surgery included ear, nose or throat surgery, wisdom tooth extraction, thoracotomy, lumbar fusion surgery, microdiscectomy, hip joint replacement surgery, knee joint replacement surgery, anterior cruciate ligament repair, knee arthroscopy, mastectomy, haemorrhoidectomy, abdominal surgery, radical prostatectomy, thyroid surgery, elective caesarean section, and laparoscopic surgery. Racemic ketamine bolus doses were predominantly 0.25 mg to 1 mg, and infusions 2 to 5 µg/kg/minute; 10 studies used only S-ketamine and one only R-ketamine. Risk of bias was generally low or uncertain, except for study size; most had fewer than 50 participants per treatment arm, resulting in high heterogeneity, as expected, for most analyses. We did not stratify the main analysis by type of surgery or any other factor, such as dose or timing of ketamine administration, and used a non-stratified analysis.Perioperative intravenous ketamine reduced postoperative opioid consumption over 24 hours by 8 mg morphine equivalents (95% CI 6 to 9; 19% from 42 mg consumed by participants given placebo, moderate-quality evidence; 65 studies, 4004 participants). Over 48 hours, opioid consumption was 13 mg lower (95% CI 10 to 15; 19% from 67 mg with placebo, moderate-quality evidence; 37 studies, 2449 participants).Perioperative intravenous ketamine reduced pain at rest at 24 hours by 5/100 mm on a visual analogue scale (95% CI 4 to 7; 19% lower from 26/100 mm with placebo, high-quality evidence; 82 studies, 5004 participants), and at 48 hours by 5/100 mm (95% CI 3 to 7; 22% lower from 23/100 mm, high-quality evidence; 49 studies, 2962 participants). Pain during movement was reduced at 24 hours (6/100 mm, 14% lower from 42/100 mm, moderate-quality evidence; 29 studies, 1806 participants), and 48 hours (6/100 mm, 16% lower from 37 mm, low-quality evidence; 23 studies, 1353 participants).Results for primary outcomes were consistent when analysed by pain at rest or on movement, operation type, and timing of administration, or sensitivity to study size and pain intensity. No analysis by dose was possible. There was no difference when nitrous oxide was used. We downgraded the quality of the evidence once if numbers of participants were large but small-study effects were present, or twice if numbers were small and small-study effects likely but testing not possible.Ketamine increased the time for the first postoperative analgesic request by 54 minutes (95% CI 37 to 71 minutes), from a mean of 39 minutes with placebo (moderate-quality evidence; 31 studies, 1678 participants). Ketamine reduced the area of postoperative hyperalgesia by 7 cm² (95% CI -11.9 to -2.2), compared with placebo (very low-quality evidence; 7 studies 333 participants). We downgraded the quality of evidence because of small-study effects or because the number of participants was below 400.CNS adverse events occurred in 52 studies, while 53 studies reported of absence of CNS adverse events. Overall, 187/3614 (5%) participants receiving ketamine and 122/2924 (4%) receiving control treatment experienced an adverse event (RR 1.2, 95% CI 0.95 to 1.4; high-quality evidence; 105 studies, 6538 participants). Ketamine reduced postoperative nausea and vomiting from 27% with placebo to 23% with ketamine (RR 0.88, 95% CI 0.81 to 0.96; the number needed to treat to prevent one episode of postoperative nausea and vomiting with perioperative intravenous ketamine administration was 24 (95% CI 16 to 54; high-quality evidence; 95 studies, 5965 participants).

AUTHORS' CONCLUSIONS

Perioperative intravenous ketamine probably reduces postoperative analgesic consumption and pain intensity. Results were consistent in different operation types or timing of ketamine administration, with larger and smaller studies, and by higher and lower pain intensity. CNS adverse events were little different with ketamine or control. Perioperative intravenous ketamine probably reduces postoperative nausea and vomiting by a small extent, of arguable clinical relevance.