A Meta-Analysis of the Utility of Preoperative Intravenous Paracetamol for Post-Caesarean Analgesia

Pre-emptive paracetamol reduces intra-operative opioid use in patients undergoing day-case oncologic breast surgery

Minimization of intra-operative opioid use is an area of ongoing research interest with several potential benefits to the patient. Pre-emptive analgesia, defined as the administration of an analgesic before surgery to prevent establishment of central sensitization of pain, is one avenue that has been explored to achieve this. A retrospective observational study was undertaken to examine the effect of pre-emptive paracetamol on intra-operative opioid requirements. The medical and operative data of 156 patients who underwent day-case wide local excision and sentinel lymph node biopsy with and without regional block surgery at our center between October 2019 and May 2022 was carried out. Data were collected on demographics, total intra-operative and immediate post-operative opioid consumption. 57 patients did not receive pre-emptive paracetamol while 90 did. Baseline characteristics were similar. Our results showed a statistically significant reduction in morphine (p <0.029) and remifentanil (p <0.007) consumption in patients who received a regional block and pre-emptive paracetamol. Those who did not receive a regional block and were given pre-emptive paracetamol had a decrease in OxyNorm (p <0.022) requirements. A combination of general anesthesia (GA), regional block and pre-emptive paracetamol reduced intra-operative consumption of Fentanyl, OxyNorm, diclofenac, dexketoprofen, and clonidine (P <0.001) when compared to just GA alone. Use of pre-emptive paracetamol in reduction of intra-operative opioid requirements showed promising results but larger studies may strengthen the evidence for this association. A multimodal analgesic approach that utilizes pre-emptive paracetamol can be a viable method to decrease intra-operative of analgesic requirements.

Multimodal Acute Pain Management in the Parturient with Opioid Use Disorder: A Review

The opioid epidemic in the United States has led to an increasing number of pregnant patients with opioid use disorder (OUD) presenting to obstetric units. Caring for this complex patient population requires an interdisciplinary approach involving obstetricians, anesthesiologists, addiction medicine physicians, psychiatrists, and social workers. The management of acute pain in the parturient with OUD can be challenging due to several factors, including respiratory depression, opioid tolerance, and opioid-induced hyperalgesia. Patients with a history of OUD can present in one of three categories: 1) those with untreated OUD; 2) those who are currently abstinent from opioids; 3) those being treated with medications to prevent withdrawal. A patient-centered, multimodal approach is essential for optimal peripartum pain relief and prevention of adverse maternal and neonatal outcomes. Medications for opioid use disorder (MOUD), previously referred to as medication-assisted therapy (MAT), include opioids like methadone, buprenorphine, and naltrexone. These are prescribed for pregnant patients with OUD, but appropriate dosing and administration of these medications are critical to avoid withdrawal in the mother. Non-opioid analgesics such as acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) can be used in a stepwise approach, and regional techniques like neuraxial anesthesia and truncal blocks offer opioid-sparing options. Other medications like ketamine, clonidine, dexmedetomidine, nitrous oxide, and gabapentinoids show promise for pain management but require further research. Overall, a comprehensive pain management strategy is essential to ensure the well-being of both the mother and the fetus in pregnant patients with OUD.

Effect of Intravenous Paracetamol on Opioid Consumption in Multimodal Analgesia After Lumbar Disc Surgery: A Meta-Analysis of Randomized Controlled Trials

Background: Intravenous paracetamol, as an adjunct to multimodal analgesia, has been shown to successfully reduce opioid consumption after joint arthroplasty, abdominal surgery, and caesarean delivery. However, there are limited data on the opioid-sparing effect of intravenous paracetamol on lumbar disc surgery. Objectives: The aim of this study was to investigate the effectiveness and safety of intravenous paracetamol for reducing opioid consumption in lumbar disc surgery. The primary outcome was cumulative opioid consumption within 24 h postoperatively. Method: We followed the PRISMA-P guidelines and used GRADE to assess the quality of evidence. The review was registered in PROSPERO under the registration number CRD42021288168. Two reviewers conducted electronic searches in PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, and Web of Science (Clarivate Analytics). Randomized controlled trials (RCTs) that compared the postoperative opioid consumption of intravenous paracetamol with placebo in lumbar discectomy were included. Results: Five trials comprising a total of 271 patients were included. The overall opioid consumption within 24 h postoperatively was reduced [mean difference (MD), -10.61 (95% CI, -16.00 to -5.22) mg, p = 0.0001, I2 = 90%] in patients with intravenous paracetamol. Intravenous paracetamol significantly reduced the postoperative pain scores at 1 h [MD, -2.37 (95%CI, -3.81 to -0.94), p = 0.001, I2 = 82%], 2 h [MD, -3.17 (95%CI, -3.85 to -2.48), p < 0.00001, I2 = 38%], 6 h [MD, -1.75 (95%CI, -3.10 to -0.40), p = 0.01], 12 h [MD, -0.96 (95%CI, -1.77 to -0.15), p = 0.02], and 24 h [MD, -0.97 (95%CI, -1.67 to -0.27), p = 0.006] compared with the placebo. There were no differences in postoperative adverse effects. Conclusion: Intravenous paracetamol reduced postoperative opioid consumption and decreased postoperative pain scores without increasing adverse effects. The overall GRADE quality of the evidence was rated as low to moderate. Intravenous paracetamol appears to be an applicable option as an important part of multimodal analgesia for postoperative analgesia after lumbar disc surgery. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, CRD42021288168.

Systematic Review of Systemic and Neuraxial Effects of Acetaminophen in Preclinical Models of Nociceptive Processing

Acetaminophen (APAP) in humans has robust effects with a high therapeutic index in altering postoperative and inflammatory pain states in clinical and experimental pain paradigms with no known abuse potential. This review considers the literature reflecting the preclinical actions of acetaminophen in a variety of pain models. Significant observations arising from this review are as follows: 1) acetaminophen has little effect upon acute nociceptive thresholds; 2) acetaminophen robustly reduces facilitated states as generated by mechanical and thermal hyperalgesic end points in mouse and rat models of carrageenan and complete Freund’s adjuvant evoked inflammation; 3) an antihyperalgesic effect is observed in models of facilitated processing with minimal inflammation (eg, phase II intraplantar formalin); and 4) potent anti-hyperpathic effects on the thermal hyperalgesia, mechanical and cold allodynia, allodynic thresholds in rat and mouse models of polyneuropathy and mononeuropathies and bone cancer pain. These results reflect a surprisingly robust drug effect upon a variety of facilitated states that clearly translate into a wide range of efficacy in preclinical models and to important end points in human therapy. The specific systems upon which acetaminophen may act based on targeted delivery suggest both a spinal and a supraspinal action. Review of current targets for this molecule excludes a role of cyclooxygenase inhibitor but includes effects that may be mediated through metabolites acting on the TRPV1 channel, or by effect upon cannabinoid and serotonin signaling. These findings suggest that the mode of action of acetaminophen, a drug with a long therapeutic history of utilization, has surprisingly robust effects on a variety of pain states in clinical patients and in preclinical models with a good therapeutic index, but in spite of its extensive use, its mechanisms of action are yet poorly understood.

Pharmacologic Stepwise Multimodal Approach for Postpartum Pain Management: ACOG Clinical Consensus No. 1

SUMMARY

Pain in the postpartum period is common and considered by many individuals to be both problematic and persistent (1). Pain can interfere with individuals' ability to care for themselves and their infants, and untreated pain is associated with risk of greater opioid use, postpartum depression, and development of persistent pain (2). Clinicians should therefore be skilled in individualized management of postpartum pain. Though no formal time-based definition of postpartum pain exists, the recommendations presented here provide a framework for management of acute perineal, uterine, and incisional pain. This Clinical Consensus document was developed using an a priori protocol in conjunction with the authors listed. This document has been revised to incorporate more recent evidence regarding postpartum pain.

Effects of the Hypnotic Alkylphenol Derivative Propofol on Breast Cancer Progression. A Focus on Preclinical and Clinical Studies

Propofol is a hypnotic alkylphenol derivative with many biological activities. It is predominantly used in anesthesia and is the most used parenteral anesthetic agent in the United States. Accumulating preclinical studies have shown that this compound may inhibit cancer recurrence and metastasis. Nevertheless, other investigations provided evidence that this compound may promote breast cancer cell progression by modulating different molecular pathways. Clinical data on this topic are scarce and derive from retrospective analyses. For this reason, we reviewed and evaluated the available data to reveal insight into this controversial issue. More preclinical and clinical investigations are necessary to determine the potential role of propofol in the proliferation of breast cancer cells.

The efficacy and safety of paracetamol for pain relief: an overview of systematic reviews

OBJECTIVE

To evaluate the efficacy and safety of paracetamol as an analgesic medication in a range of painful conditions.

STUDY DESIGN

Systematic review of systematic reviews of the analgesic effects of paracetamol in randomised, placebo-controlled trials. Conduct of systematic reviews was assessed with AMSTAR-2; confidence in effect estimates (quality of evidence) was assessed with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria.

DATA SOURCES

MEDLINE, EMBASE, PsycINFO, Cochrane Database of Systematic Reviews; systematic reviews published 1 January 2010 - 30 April 2020.

DATA SYNTHESIS

We extracted pain and adverse events outcomes from 36 systematic reviews that assessed the efficacy of paracetamol in 44 painful conditions. Continuous pain outcomes were expressed as mean differences (MDs; standardised 0-10-point scale); dichotomous outcomes were expressed as risk ratios (RRs). There is high quality evidence that paracetamol provides modest pain relief for people with knee or hip osteoarthritis (MD, -0.3 points; 95% CI, -0.6 to -0.1 points) and after craniotomy (MD, -0.8 points; 95% CI, -1.4 to -0.2 points); there is moderate quality evidence for its efficacy in tension-type headache (pain-free at 2 hours: RR, 1.3; 95% CI, 1.1-1.4) and perineal pain soon after childbirth (patients experiencing 50% pain relief: RR, 2.4; 95% CI, 1.5-3.8). There is high quality evidence that paracetamol is not effective for relieving acute low back pain (MD, 0.2 points; 95% CI, -0.1 to 0.4 points). Evidence regarding efficacy in other conditions was of low or very low quality. Frequency of adverse events was generally similar for people receiving placebo or paracetamol, except that transient elevation of blood liver enzyme levels was more frequent during repeated administration of paracetamol to patients with spinal pain (RR, 3.8; 95% CI, 1.9-7.4).

CONCLUSIONS

For most conditions, evidence regarding the effectiveness of paracetamol is insufficient for drawing firm conclusions. Evidence for its efficacy in four conditions was moderate to strong, and there is strong evidence that paracetamol is not effective for reducing acute low back pain. Investigations that evaluate more typical dosing regimens are required.

PROSPERO REGISTRATION

CRD42015029282 (prospective).

Perioperative intravenous acetaminophen and postcesarean pain control: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This study aimed to determine the efficacy of perioperative (pre- or intraoperative) intravenous acetaminophen in improving postcesarean pain control in healthy women receiving regional anesthesia.

DATA SOURCES

MEDLINE, Ovid, ClinicalTrials.gov, and Scopus were searched from their inception to September 2019.

STUDY ELIGIBILITY CRITERIA

A systematic review of the literature was performed to identify all randomized placebo-controlled trials examining the effect of perioperative intravenous acetaminophen on postcesarean pain control and other postoperative outcomes. Included trials examined women who were healthy and received regional anesthesia before cesarean delivery at term.

STUDY APPRAISAL AND SYNTHESIS METHODS

The primary outcome was 24-hour postoperative pain scores with movement as measured by the individual studies. Secondary outcomes included intravenous morphine milligram equivalents used postoperatively. Meta-analysis was performed using the random effects model of DerSimonian and Laird, to produce summary treatment effects in terms of mean difference with 95% confidence interval.

RESULTS

Notably, 4 randomized placebo-controlled trials were identified that met the inclusion criteria with a total of 190 in the intervention arm vs 174 women in the control group. Patients in the intervention group received 1000 mg intravenous acetaminophen in 3 of the studies and 2000 mg intravenous acetaminophen in 1 study. All patients received regional anesthesia before surgery. The medication was given anywhere from 1 hour before surgery to intraoperatively immediately after delivery of the fetus. Pain scores 24 hours after surgery were only available in 1 study. The use of opioids as measured by morphine milligram equivalents after surgery was similar for patients receiving perioperative intravenous acetaminophen and those receiving placebo (38.7 vs 42.55; mean difference, -2.54; 95% confidence interval, -9.24 to 4.16). Only 1 study showed decreased postoperative pain scores when using perioperative intravenous acetaminophen, and this was limited to the first 4 hours after surgery. Importantly, these patients did not receive long-acting neuraxial opioids, which may account for the finding of improved pain control in the early postoperative period.

CONCLUSION

There are limited data available on the use of perioperative intravenous acetaminophen for cesarean delivery performed at term with regional anesthesia. The use of long-acting neuraxial opioids may make perioperative (pre- or intracesarean) intravenous acetaminophen unnecessary, whereas intravenous (or oral) acetaminophen may become more effective as neuraxial opioid analgesia wears off. More level-1 data are needed.

Pre-emptive analgesic efficacy of injected ketorolac in comparison to other agents for third molar surgical removal: a systematic review

This study aimed to evaluate and compare the pre-emptive analgesic efficacy of injected ketorolac to that of other agents for impacted third molar surgical removal in a healthy population.

PubMed, Ovid SP, Cochrane databases were filtered from 1980 to July 2020 for potential papers using relevant MeSH terms and pre-specified inclusion and exclusion criteria independently by reviewers. Studies that compared pre-emptive intramuscular or intravenous administration of ketorolac to other agents were evaluated. The outcomes sought were self-reported postoperative pain (patient-perceived pain), median duration for rescue analgesic medication, total number of analgesics consumed in the recovery period, and global assessment (overall patient satisfaction) after the recovery period.

Six studies were included in the final evaluation. The outcome of pain perception and the number of analgesics taken were significantly lower in the ketorolac group (intramuscular or intravenous) in most of the studies (n=5) than in the group of other drugs. The mean time for rescue analgesia intake was higher for the ketorolac group, and global assessment scores were also better in the ketorolac group.

Although the included studies show significantly better outcomes such as postoperative pain, median time taken for rescue medication, total number of analgesics taken, and overall patient satisfaction with injected ketorolac group in comparison to injected diclofenac, dexamethasone, and tramadol, definitive conclusions cannot be made regarding the superiority of injected Ketorolac as a pre-emptive agent. A greater number of randomized control trials with a proper protocol are needed to make definitive conclusions.

Opioid-free multimodal analgesia pathway to decrease opioid utilization after cesarean delivery

AIM

To evaluate an opioid-free multimodal analgesic pathway (MAP) to decrease opioid utilization after cesarean delivery (CD) compared to historic data of our institution prior to using MAP for pain management (pre-MAP).

METHODS

The MAP was implemented in three phases from September 2018 to August 2019. Patients received 1000 mg intravenous (IV) acetaminophen with 30 mg IV ketorolac at 0 (arrival time at recovery room), 6, 12 and 18 h of postoperative course. On the 2nd and the 3rd postoperative days, patients were monitored for pain every 6 h by Numeric Pain Intensity Scale (0 = no pain to 10 = severe pain) and administered 600 mg oral ibuprofen for a pain score between 0 and 4, 600 mg oral ibuprofen and/or 650 mg oral acetaminophen for a pain score between 5-6, 1000 mg IV acetaminophen and/or 30 mg of IV or intramuscular ketorolac for a pain score between 7 and 10. Five milligrams of oral oxycodone was reserved for rescue if all protocol options were exhausted. Patients were discharged with 600 mg oral ibuprofen without opioid prescription. Likert surveys measuring patient satisfaction of pain control were administered during phase 3.

RESULTS

Inpatient and outpatient opioid consumption rates were significantly decreased from 45%, 18% to 23.8%, 8.5% after MAP implementation (P-value <0.001). More than 90% of patients reported that their pain was well controlled and willing to request the same regimen for a future CD.

CONCLUSION

MAP Implementation after CD significantly reduced inpatient and outpatient opioid consumption compared to pre-MAP results while maintaining high patients' satisfaction with pain control.

Optimizing Perioperative Use of Opioids: A Multimodal Approach

Purpose of Review

The main purpose of this article is to review recent literature regarding multimodal analgesia medications, citing their recommended doses, efficacy, and side effects. The second part of this report will provide a description of drugs in different stages of development which have novel mechanisms with less side effects such as tolerance and addiction.

Recent Findings

Multimodal analgesia is a technique that facilitates perioperative pain management by employing two or more systemic analgesics along with regional anesthesia, when possible. Even though opioids and non-opioid analgesics remain the most common medication used for acute pain management after surgery, they have many undesirable side effects including the potential for misuse. Newer analgesics including peripheral acting opioids, nitric oxide inhibitors, calcitonin gene-related peptide receptor antagonists, interleukin-6 receptor antagonists and gene therapy are under intensive investigation.

Summary

A patient's first exposure to opioids is often in the perioperative setting, a vulnerable time when multimodal therapy can play a large role in decreasing opioid exposure. Additionally, the current shift towards faster recovery times, fewer post-operative complications and improved cost-effectiveness during the perioperative period has made multimodal analgesia a central pillar of Enhanced Recovery After Surgery (ERAS) protocols.