Preemptive use of ketamine on post operative pain of appendectomy

Perioperative pain management for appendicectomy: A systematic review and Procedure-specific Postoperative Pain Management recommendations

BACKGROUND

Despite being a commonly performed surgical procedure, pain management for appendicectomy is often neglected because of insufficient evidence on the most effective treatment options.

OBJECTIVE

To provide evidence-based recommendations by assessing the available literature for optimal pain management after appendicectomy.

DESIGN AND DATA SOURCES

This systematic review-based guideline was conducted according to the PROSPECT methodology. Relevant randomised controlled trials, systematic reviews and meta-analyses in the English language from January 1999 to October 2022 were retrieved from MEDLINE, Embase and Cochrane Databases using PRISMA search protocols.

ELIGIBILITY CRITERIA

We included studies on adults and children. If articles reported combined data from different surgeries, they had to include specific information about appendicectomies. Studies needed to measure pain intensity using a visual analogue scale (VAS) or a numerical rating scale (NRS). Studies that did not report the precise appendicectomy technique were excluded.

RESULTS

Out of 1388 studies, 94 met the inclusion criteria. Based on evidence and consensus, the PROSPECT members agreed that basic analgesics [paracetamol and nonsteroidal anti-inflammatory drugs (NSAIDs)] should be administered perioperatively for open and laparoscopic appendicectomies. A laparoscopic approach is preferred because of lower pain scores. Additional recommendations for laparoscopic appendicectomies include a three-port laparoscopic approach and the instillation of intraperitoneal local anaesthetic. For open appendicectomy, a preoperative unilateral transverse abdominis plane (TAP) block is recommended. If not possible, preincisional infiltration with local anaesthetics is an alternative. Opioids should only be used as rescue analgesia. Limited evidence exists for TAP block in laparoscopic appendicectomy, analgesic adjuvants for TAP block, continuous wound infiltration after open appendicectomy and preoperative ketamine and dexamethasone. Recommendations apply to children and adults.

CONCLUSION

This review identified an optimal analgesic regimen for open and laparoscopic appendicectomy. Further randomised controlled trials should evaluate the use of regional analgesia and wound infiltrations with adequate baseline analgesia, especially during the recommended conventional three-port approach.

REGISTRATION

The protocol for this study was registered with the PROSPERO database (Registration No. CRD42023387994).

Value of indomethacin suppository for preoperative analgesia and anti-inflammation in laparoscopic appendectomy: a protocol of prospective, double-blinded, single-centre, randomised controlled trial in China

INTRODUCTION

Postoperative pain has always been a problem for patients and surgeons. Local inflammation, surgical trauma and pain in the body can cause a systemic stress response and immune imbalance, which can affect the patient's rapid recovery. Currently, most of the perioperative pain management is focused on the postoperative phase. The non-steroidal anti-inflammatory drug indomethacin suppository has antipyretic and analgesic effects. This study will evaluate the value of indomethacin suppository for analgesia and anti-inflammation before laparoscopic appendectomy (LA).

METHODS AND ANALYSIS

A single-centre, double-blinded (clinician, assessor, data entry), randomised controlled trial will be conducted in 128 adult patients undergoing LA under emergency general anaesthesia with a Visual Analogue Scale (VAS) >2. The trial was divided into two groups (n=64) using a randomised number table: group A will be given 100 mg of indomethacin suppository rectally and group B will be given 8 mg of intravenous lornoxicam. The postoperative analgesic effect, inflammatory response and incidence of postoperative adverse effects will be compared.

ETHICS AND DISSEMINATION

The study is in accordance with the Declaration of Helsinki and will be conducted in accordance with the principles of Good Clinical Practice. This trial was approved by the Ethics Committee of Beijing Luhe Hospital, Capital Medical University (2021-LHKY-123-02). We will disseminate our study findings at national and international paediatric research conferences.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry (ChiCTR2200062004).

Analgesic efficacy of ketamine and magnesium after laparoscopic sleeve gastrectomy: A randomized, double-blind, placebo-controlled trial

Background Ketamine and magnesium are antagonists of the N-methyl-d-aspartate receptor, and are valuable adjuvants for multimodal analgesia and opioid sparing. Data are limited regarding the opioid sparing efficacy of the combined intraoperative application of these agents in laparoscopic bariatric surgery. The objective of this study was to compare the postoperative opioid sparing properties of a single intraoperative dose of ketamine versus a combination of single doses of ketamine and magnesium after laparoscopic gastric sleeve resection in bariatric patients. Methods One hundred and twenty- six patients were randomly assigned to receive single boluses of ketamine alone 0.5 mg kg^-1 IV (ketamine group); combined ketamine bolus of 0.5 mg kg^-1 IV and magnesium 2 g IV (ketamine and magnesium group); or placebo. Opioid consumption at 24 h (in morphine equivalents); pain at rest; postoperative nausea and vomiting impact score; sedation scores; and trends of transcutaneous carbon-di-oxide values were analysed. Results The median (inter-quartile range [range]) morphine consumption at 24 h were 32 (24-47 [4.8-91]) mg in the ketamine group, 37 (18-53 [1-144]) mg in the ketamine and magnesium group, and 26 (21-36 [5-89]) mg in the control group and were not significantly different between the groups. There were no differences for all other outcomes examined. Conclusion Combined single intraoperative bolus doses of ketamine and magnesium did not result in postoperative opioid sparing after laparoscopic gastric sleeve resection.

Intra-operative low-dose ketamine does not reduce the cost of post-operative pain management after surgery: a randomized controlled trial in a low-income country

BACKGROUND

In developing countries, post-operative pain remains underestimated and undertreated due to economic constraints, lack of awareness and limited resources. In contrast, ketamine is an effective, readily available, easy to use and inexpensive drug frequently used in poor settings.

OBJECTIVES

The aim of this study was to explore the overall reduction in the medication treatment cost of acute post-operative pain by adding intra-operative low-dose ketamine to traditional intravenous morphine for surgery in a low-income country.

METHODS

A double blind randomized controlled trial with placebo-controlled parallel group was performed in Mulago National Hospital (Uganda). Consenting adults scheduled for elective surgery were randomized into two study arms: Group K received ketamine 0.15mg/kg bolus at induction and a continuous infusion of 0.12 mg/kg/hour till start of skin closure; Group C (control) received normal saline. Both groups received Morphine 0.1 mg/kg IV at debulking. The total medication cost was registered. NRS pain scores and other measurements such vital signs and incidence of major and minor side effects were also recorded.

RESULTS

A total of 46 patients were included. Patients' baseline characteristics were comparable in both groups. No statistically significant difference was found between the groups concerning the overall medication cost of post-operative pain management. Pain scores, patients' satisfaction in the first 24 hours after surgery and hospital length of stay were similar in both groups.

CONCLUSION

Our results do not support the utilization of intra-operative low dose ketamine as a cost-saving post-operative pain treatment strategy for all types of surgery in low-resource settings.

Expanding Role of NMDA Receptor Antagonists in the Management of Pain

Pain management is complex regardless of whether the pain is acute or chronic in nature or non-cancer or cancer related. In addition, relatively few pain pharmacotherapy options with adequate efficacy and safety data currently exist. Consequently, interest in the role of NMDA receptor antagonists as a pharmacological pain management strategy has surfaced. This narrative review provides an overview of the NMDA receptor and elaborates on the pharmacotherapeutic profile and pain management literature findings for the following NMDA receptor antagonists: ketamine, memantine, dextromethorphan, and magnesium. The literature on this topic is characterized by small studies, many of which exhibit methodological flaws. To date, ketamine is the most studied NMDA receptor antagonist for both acute and chronic pain management. Although further research about NMDA receptor antagonists for analgesia is needed and the optimal dosage/administration regimens for these drugs have yet to be determined, ketamine appears to hold the most promise and may be of particular value in the perioperative pain management realm.

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.

Intravenous Anesthesia With Bispectral Index Monitoring vs Inhalational Anesthesia for Rhytidoplasty: A Randomized Clinical Trial

IMPORTANCE

Minor adverse effects related to anesthesia are common and worrisome to patients, including perioperative vomiting, gagging on the endotracheal tube, incisional pain, and nausea. A previously published intravenous anesthesia protocol reports extremely low rates of postoperative nausea and vomiting (<1%) and decreases in postoperative pain perception compared with rates reported following administration of inhalational anesthetics.

OBJECTIVE

To evaluate and compare postoperative outcomes in patients after administration of combined propofol and ketamine hydrochloride anesthesia with bispectral index monitoring (PKA-BIS protocol) vs inhalational anesthesia (IA) during lower rhytidoplasty.

DESIGN, SETTING, AND PARTICIPANTS

We performed a prospective, double-blind, randomized comparison trial of the PKA-BIS protocol and IA in 30 consecutive female patients undergoing rhytidoplasty by a single surgeon at a single outpatient surgery center from October 2013 to June 2014.

MAIN OUTCOMES AND MEASURES

Outcome measures included nausea, vomiting, pain, overall feeling of well-being, time to awaken, time to discharge, and cost. Patient measures were recorded using a combination of a 40-item validated postoperative quality of recovery questionnaire (QOR-40) and visual analog scales (VASs). Results were recorded immediately after surgery and on postoperative days 1 and 7.

RESULTS

A statistically significant reduction in emergence time (mean [SD], 29.8 [10.6] vs 46.0 [10.2] minutes; P < .001) and time to meet discharge criteria (51.4 [19.3] vs 66.1 [12.9] minutes; P = .02) was seen in patients in the PKA-BIS group. Patient-reported (subjective) postoperative nausea (3 of 15 [20%] vs 7 of 15 patients [47%]; P = .12; χ2 = 2.40), vomiting (0 vs 2 of 15 patients [13%]; P = .14; χ2 = 2.14), and confusion on the day of surgery (3 of 15 [20%] vs 6 of 14 patients [43%]; P = .18; χ2 = 1.77) were also decreased in the PKA-BIS group, but these differences did not reach significance. Differences in global recovery scores (QOR-40 scores in the postanesthesia care unit, 158.13 [22.68] vs 155.33 [18.09]; P = .71; at day 1, 166.47 [26.39] vs 166.00 [16.00]; P = .96), postoperative overall feeling of well-being (VAS scores at day 1, 6.10 vs 6.26; at day 7, 7.49 vs 8.00), and postoperative pain perception (VAS scores at day 1, 3.40 vs 3.65; at day 7, 2.26 vs 1.81) between the PKA-BIS and IA groups, respectively, did not reach significance. The costs of anesthesia administration were similar between the PKA-BIS ($10.37/h) and IA ($8.47/h to $9.87/h) groups.

CONCLUSIONS AND RELEVANCE

The PKA-BIS protocol for anesthesia appears to be a comparable alternative to traditional IA in patients undergoing elective rhytidoplasty. A larger patient sample size is needed to determine whether trends toward decreased nausea, vomiting, and postoperative confusion and differences in postoperative pain perception are significant.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02410460.

LEVEL OF EVIDENCE

1.

Comparison of pregabalin versus ketamine in postoperative pain management in breast cancer surgery

Background:

Breast surgery compromises one of the most common cancer surgeries in females and commonly followed by acute postoperative pain. Pregabalin and ketamine have been used in many previous studies and was found to have a good analgesic profile. We assumed that pregabalin and ketamine can be used in control of postoperative pain in female patients undergoing breast cancer surgery.

Material and Methods:

Ninety female patients scheduled for cancer breast surgery were allocated in three groups (30 patients each), control group (group c) received preoperative placebo, pregabalin group (group p) received oral 150 mg pregabalin 1 h before surgery, ketamine group (group k) received intravenous (IV) 0.5 mg/kg ketamine with induction of anesthesia followed by 0.25 mg/kg/h IV throughout the surgery. All patients received general anesthesia and after recovery, the three groups were assessed in the first postoperative 24 h for postoperative visual analog scale (VAS), total 24 h morphine consumption, incidence of postoperative nausea and vomiting (PONV), sedation score >2 and any complications from the drugs used in the study.

Results:

The use of pregabalin or ketamine was found to reduce total postoperative morphine consumption with P < 0.001. There was no difference between pregabalin and ketamine groups in opioid requirement. There was no difference between the three groups in postoperative VAS scores or incidence of PONV and sedation score >2.

Conclusion:

The use of preoperative oral 150 mg pregabalin 1 h before surgery or IV 0.5 mg ketamine with induction of anesthesia can reduce postoperative opioid consumption in breast cancer surgery without change in sedation or PONV and with a good safety profile.

The Comparison of Infusion of Two Different Sedation Regimens with Propofol and Ketamine Combination During Plastic and Reconstructive Surgery

OBJECTIVE

Anesthetic agents are often combined to enhance their therapeutic effects while minimizing adverse events. The aim of this study was to evaluate the effects of two different sedation regimens of ketamine and propofol combination via infusion on perioperative variables in patients who underwent plastic and reconstructive surgery.

METHODS

This randomized double-blind clinical trial was done on 80 patients who were randomized to two groups; group 1 (n = 40) received a 2:1 mixture of 9 mg/ml propofol and 4.5 mg/ml ketamine, and group 2 (n = 40) received a 4:1 mixture of 9 mg/ml propofol and 2.25 mg/ml ketamine. After premedication and before local anesthetic injection, the infusion of mixtures was adjusted to attain the Ramsay sedation scores of 5 in both groups. We recorded induction time, sedation efficacy, cardiovascular and respiratory events, recovery time, and incidence of adverse events during and after the procedure.

RESULTS

The mean of volume infusion of mixtures in the beginning of the procedure was higher in group 2 (3.2 ± 1. 2 ml) than in group 1 (2.4 ± 0.8 ml) (p < 0.001). The induction time for sedation was 2.8 ± 0.8 min and 2.6 ± 0.4 min in group 1 and group 2, respectively (p = 0. 92). The number of oversedated patients was greater in group 2 compared to group 1 but not statistically significant (p = 0. 80). The sedation efficacy was similar between the two groups. The hemodynamic changes during the procedure were greater in group 2 compared to group 1 (p = 0. 001). The recovery time was not significantly different between the two groups (p = 0.43). The mean pain score in the recovery room was lower in group 1 than group 2 (1.2 ± 0.8 vs 2.8 ± 1.8, p = 0. 01). Moreover, 4 (10 %) patients in group 1 and 10 (25 %) patients in group 2 needed opioid administration (p = 0. 02). Other postoperative adverse events were similar between the two groups.

CONCLUSION

We recommend the use of a 2:1 combination of propofol-ketamine, because it reduced the rescue propofol requirement and consequently produced lower cardiovascular and respiratory depression effects and also less postoperative pain.

Preoperative low-dose ketamine has no preemptive analgesic effect in opioid-naïve patients undergoing colon surgery when nitrous oxide is used - a randomized study

BACKGROUND

The analgesic properties of ketamine are associated with its non-competitive antagonism of the N-methyl-D-aspartate receptor; these receptors exhibit an excitatory function on pain transmission and this binding seems to inhibit or reverse the central sensitization of pain. In the literature, the value of this anesthetic for preemptive analgesia in the control of postoperative pain is uncertain. The objective of this study was to ascertain whether preoperative low-dose ketamine reduces postoperative pain and morphine consumption in adults undergoing colon surgery.

METHODS

In a double-blind, randomized trial, 48 patients were studied. Patients in the ketamine group received 0.5 mg/kg intravenous ketamine before surgical incision, while the control group received normal saline. The postoperative analgesia was achieved with a continuous infusion of morphine at 0.015 mg∙kg-¹∙h-¹ with the possibility of 0.02 mg/kg bolus every 10 min. Pain was assessed using the Visual Analog Scale (VAS), morphine consumption, and hemodynamic parameters at 0, 1, 2, 4, 8, 12, 16, and 24 hours postoperatively. We quantified times to rescue analgesic (Paracetamol), adverse effects and patient satisfaction.

RESULTS

No significant differences were observed in VAS scores between groups (P>0.05), except at 4 hours postoperatively (P=0.040). There were no differences in cumulative consumption of morphine at any time point (P>0.05). We found no significant differences in incremental postoperative doses of morphine consumption in bolus, except at 12 h (P =0.013) and 24 h (P =0.002). The time to first required rescue analgesia was 70 ± 15.491 min in the ketamine group and 44 ± 19.494 min in the control (P>0.05). There were no differences in hemodynamic parameters or patient satisfaction (P>0.05).

CONCLUSIONS

Preoperative low-dose-ketamine did not show a preemptive analgesic effect or efficacy as an adjuvant for decreasing opioid requirements for postoperative pain in patients receiving intravenous analgesia with morphine after colon surgery.

Effects of adding ketamine to fentanyl plus acetaminophen on postoperative pain by patient controlled analgesia in abdominal surgery

BACKGROUND

Postoperative pain is one of the most important complications encountered after surgery. A number of options are available for treating pain following surgery. One of those options is the use of intravenous patient-controlled analgesia (PCA). Ketamine is an anesthetic drug relieving pain with its NMDA receptor antagonistic effect.

OBJECTIVES

This study is aiming at better pain management after abdominal surgery; the effects of adding ketamine to intravenous fentanyl plus acetaminophen PCA were evaluated.

PATIENTS AND METHODS

In a double-blind randomized clinical trial 100 patients, ASA I or II, 20 - 60 years old were divided into two groups. These patients were abdominal surgery candidates. In order to control postoperative pain in the control group an IV patient-control analgesia (PCA) containing fentanyl 10 μg/mL plus acetaminophen 10 mg/mL was instructed to be used for the patients, but the patients in ketamine group received ketamine 0.5 mg/mL plus control group PCA content. During the first 48 hours after surgery, ketamine patients were evaluated every 8 hours (at rest, while moving and coughing) to determine their pain scores using VAS scale, sedation score, additional analgesics, nausea and vomiting.

RESULTS

There were no significant demographic differences between two groups. Pain scores (at rest, while moving and coughing) during the first 48 hours were not significantly different between two groups (P values = 0.361, 0.367 and 0.204, respectively). Nausea scores were significantly lower in the ketamine group (P = 0.026).

CONCLUSIONS

The addition of ketamine to intravenous fentanyl plus acetaminophen PCA had not extra effects in relieving post abdominal surgery pain.

The Effect of Low-dose Ketamine on Post-caesarean Delivery Analgesia after Spinal Anesthesia

Background

Ketamine, an N-methyl-D-aspartate receptor antagonist, might play a role in postoperative analgesia, but its effect on postoperative pain after caesarean section varies with study design. We investigated whether the preemptive administration of low-dose intravenous ketamine decreases postoperative opioid requirement and postoperative pain in parturients receiving intravenous fentanyl with patient-controlled analgesia (PCA) following caesarean section.

Methods

Spinal anesthesia was performed in 40 parturients scheduled for elective caesarean section. Patients in the ketamine group received a 0.5 mg/kg ketamine bolus intravenously followed by 0.25 mg/kg/h continuous infusion during the operation. The control group received the same volume of normal saline. Immediately after surgery, the patients were connected to a PCA device set to deliver 25-µg fentanyl as an intravenous bolus with a 15-min lockout interval and no continuous dose. Postoperative pain was assessed using the cumulative dose of fentanyl and visual analog scale (VAS) scores at 2, 6, 24, and 48 h postoperatively.

Results

Significantly less fentanyl was used in the ketamine group 2 h after surgery (P = 0.033), but the difference was not significant at 6, 12, and 24 h postoperatively. No significant differences were observed between the VAS scores of the two groups at 2, 6, 12, and 24 h postoperatively.

Conclusions

Intraoperative low-dose ketamine did not have a preemptive analgesic effect and was not effective as an adjuvant to decrease opioid requirement or postoperative pain score in parturients receiving intravenous PCA with fentanyl after caesarean section.