Improved Outcomes Associated With the Use of Intravenous Acetaminophen for Management of Acute Post-Surgical Pain in Cesarean Sections and Hysterectomies

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.

Measuring Individual Benefits of Medical Treatments Using Longitudinal Hospital Data with Non-Ignorable Missing Responses Caused by Patient Discharge: Application to the Study of Benefits of Pain Management Post Spinal Fusion

Electronic health records (EHR) provide valuable resources for longitudinal studies and understanding risk factors associated with poor clinical outcomes. However, they may not contain complete follow-ups, and the missing data may not be at random since hospital discharge may depend in part on expected but unrecorded clinical outcomes that occur after patient discharge. These non-ignorable missing data requires appropriate analysis methods. Here, we are interested in measuring and analyzing individual treatment benefits of medical treatments in patients recorded in EHR databases. We present a method for predicting individual benefits that handles non-ignorable missingness due to hospital discharge. The longitudinal clinical outcome of interest is modeled simultaneously with the hospital length of stay using a joint mixed-effects model, and individual benefits are predicted through a frequentist approach: the empirical Bayesian approach. We illustrate our approach by assessing individual pain management benefits to patients who underwent spinal fusion surgery. By calculating sample percentiles of empirical Bayes predictors of individual benefits, we examine the evolution of individual benefits over time. We additionally compare these percentiles with percentiles calculated with a Monte Carlo approach. We showed that empirical Bayes predictors of individual benefits do not only allow examining benefits in specific patients but also reflect overall population trends reliably.

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.

Inpatient Perioperative Formulary Restriction of Intravenous Acetaminophen at Vizient Partner Hospitals: A National Survey of Pharmacists

Purpose: Despite potential benefits of intravenous (i.v.) administration of acetaminophen (APAP), consistent outcome data are lacking. This, combined with the higher acquisition cost of the drug, has led to variation in i.v. APAP management strategies. This project evaluated the contemporary formulary status and restrictions of i.v. APAP in the perioperative setting. Methods: A survey focusing on i.v. APAP formulary restriction in the perioperative setting was developed by the Vizient Pharmacy Research Committee and distributed to Vizient Pharmacy Program participant listservs for Pharmacy Directors or Drug Information Pharmacists. The four survey domains included hospital characteristics, perioperative i.v. APAP formulary status and prescribing restrictions, perioperative i.v. APAP use, and perioperative i.v. APAP medication use evaluation (MUE) results. Responses were collected and summarized, and primary outcomes were evaluated using Fisher's exact test. Results: A total of 1195 surveys were distributed with a response rate of 19%. Respondents were equally distributed between academic medical centers (AMC) and non-academic medical centers (non-AMC). Two cohorts were examined: those with i.v. APAP on formulary and those without. The non-AMCs showed a larger proportion of hospitals with the medication on formulary (P = .041). Regarding formulary decision-making, the AMCs were more considerate of value. Several different practices were employed to limit or restrict i.v. APAP. Conclusion: A survey of directors of pharmacy and drug information specialists revealed that the majority of hospitals have i.v. APAP on formulary for perioperative use, but use is restricted. Differences in i.v. APAP formulary practices between AMCs and non-AMCs warrant further consideration.

Assessing efficacy of intravenous acetaminophen for perioperative pain control for oocyte retrieval: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To compare the effect of preoperative intravenous (IV) acetaminophen versus oral (PO) acetaminophen or placebo on postoperative pain scores and the time to discharge in women undergoing oocyte retrieval.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Single academic fertility center.

PATIENT(S)

Women aged 18-43 years undergoing oocyte retrieval.

INTERVENTION(S)

Randomization to preoperative 1,000 mg IV acetaminophen and PO placebo (group A), IV placebo and 1,000 mg PO acetaminophen (group B), or IV and PO placebo (group C) MAIN OUTCOME MEASURE(S): Difference in patient-reported postoperative visual analog scale pain scores from baseline and the time to discharge.

RESULT(S)

Of the 159 women who completed the study, there were no differences in the mean postoperative pain score differences or the time to discharge. Although not statistically significant, the mean postoperative opioid dose requirement in group A was lower than that in groups B and C (0.24 vs. 0.59 vs. 0.58 mg IV morphine equivalents, respectively) due to fewer women in group A requiring rescue pain medication (8% vs. 19% vs. 15%, respectively). Group A also reported less constipation when compared with groups B and C (19% vs. 33% vs. 40%, respectively). The rates of postoperative nausea were similar, and there were no differences in embryology or early pregnancy outcomes between the study groups.

CONCLUSION(S)

Preoperative IV acetaminophen for women undergoing oocyte retrieval did not reduce postoperative pain scores or shorten the time to discharge when compared with PO acetaminophen or placebo and, thus, cannot currently be recommended routinely in this patient population.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03073980.

Analgesic efficacy of ultrasound-guided transversus abdominis plane block after cesarean delivery: A systematic review and meta-analysis

PURPOSE

The meta-analysis is aimed to further access the analgesic efficacy of ultrasound-guided transversus abdominis plane (USG-TAP) block after cesarean section (CS).

METHODS

Electronic databases were searched for eligible studies. Primary objectives were pain-related outcomes. Weighted mean differences (WMDs) or standardized mean differences (SMDs), as well as risk ratios (RRs) with 95% confidence intervals (CIs), were used to calculate estimates. Subgroup analyses were done based on whether USG-TAP blocks were performed with long-acting intrathecal opioids (ITO).

RESULTS

A total of 17 studies were included. When compared with control groups (placebo or no blocks), USG-TAP block resulted in lower cumulative opioid consumption at 6 h (WMD: -8.32; 95% CI: -14.86, -1.79), 12 h (WMD: -10.75; 95% CI: -20.93, -0.57), and 24 h (WMD: -12.71, 95% CI: -21.28, -4.14). No significant differences were demonstrated among dynamic or resting pain scores. Patients in USG-TAP groups needed longer time to request first analgesic (WMD: 3.56; 95% CI: 1.43, 5.68) and showed a lower requirement of opioid rescue analgesia for breakthrough severe pain during 24 h (RR: 0.40; 95% CI: 0.18, 0.86). Subgroup analyses showed USG-TAP blocks did not afford additional benefit in the presence of intrathecal morphine. Also, reduced need for antiemetics after CS and higher maternal satisfaction were provided by USG-TAP blocks.

CONCLUSION

USG-TAP block can provide significantly effective analgesia for patients who underwent CS in the absence of long-acting ITO and therefore are worth promoting in the setting of long-acting ITO being unfeasible.

Anesthetic considerations and postoperative pain management in radical penectomy: Case report

Radical penectomy (RP) is infrequently performed as it is reserved for specific cases of penile cancer, hence the paucity of reports regarding surgical and anesthetic considerations. Acute postoperative pain, chronic post-surgical pain, concomitant mood disorders as well as a profound impact on the patient’s quality of life have been documented. This case is of a patient with diabetes and coronary heart disease, who presented with advanced, overinfected penile cancer, depressive disorder and a history of pain of neuropathic characteristics. The patient underwent radical penectomy using a combined spinal-epidural technique for anesthesia. Preoperatively, the patient was treated with pregabalin and magnesium sulphate, and later received a blood transfusion due to intraoperative blood loss. Adequate intra and postoperative analgesia was achieved with L-bupivacaine given through a peridural catheter during one week. Recovery was good, pain was stabilized to preoperative levels and the patient received pharmacological support and follow-up by psychiatry and the pain team.

Preoperative Intravenous Versus Oral Acetaminophen in Outpatient Surgery: A Double-Blinded, Randomized Control Trial

PURPOSE

Preoperative acetaminophen is recognized as an effective part of the multimodal approach to perioperative pain management. The present study, conducted between April 12, 2018 and February 14, 2019, examined whether there are differences in patient-reported pain, postoperative opioid consumption, negative opioid effects, length of postanesthesia care unit stay, and patient satisfaction with pain control between patients who receive intravenous (IV) acetaminophen and patients who receive oral acetaminophen.

DESIGN

This double-blinded, randomized controlled trial was conducted among 120 patients undergoing outpatient surgery.

METHODS

Patients were randomized to receive preoperatively either intravenous (IV) acetaminophen (and oral placebo) or oral acetaminophen (and IV placebo). Results were analyzed using SPSS statistical software; statistical analyses consisted of Mann-Whitney U test, independent samples t test, and χ² test. In all analyses, a P value less than .05 was considered significant.

FINDINGS

There were no significant differences in any outcome measures based on the route of acetaminophen administration.

CONCLUSIONS

The findings of the present study support the practice of administering oral acetaminophen, as opposed to IV acetaminophen, preoperatively as part of the multimodal approach to manage postoperative pain in patients able to tolerate preoperative oral medications.

Anesthesia considerations and post-operative pain management in pregnant women with chronic opioid use

The prevalence of opioid use disorder in pregnancy has escalated markedly in recent years. Chronic opioid use during pregnancy poses several challenges for providing adequate analgesia and anesthesia in the peripartum period. These challenges include the potential for withdrawal, opioid tolerance and opioid-induced hyperalgesia. Here we discuss alterations in analgesic pharmacokinetics and pharmacodynamics that are associated with chronic opioid use. In addition, when treating pain in patients with opioid use disorder it is important to distinguish between different subgroups. In this review, we will discuss practical management strategies for parturients with (1) untreated opioid use disorder, (2) parturients on medication-assisted treatment (methadone, buprenorphine) and (3) patients recovering from opioid use disorder that are currently abstinent. Finally, we offer an overview of non-opioid strategies that may be utilized as part of a multimodal approach to providing optimal analgesia in this patient population.

Isoform-specific therapeutic control of sulfonation in humans

The activities of hundreds, perhaps thousands, of metabolites are regulated by human cytosolic sulfotransferases (SULTs) - a 13-member family of disease relevant enzymes that catalyze transfer of the sulfuryl moiety (-SO₃) from PAPS (3'-phosphoadenosine 5'-phosphosulfonate) to the hydroxyls and amines of acceptors. SULTs harbor two independent allosteric sites, one of which, the focus of this work, binds non-steroidal anti-inflammatory drugs (NSAIDs). The structure of the first NSAID-binding site - that of SULT1A1 - was elucidated recently and homology modeling suggest that variants of the site are present in all SULT isoforms. The objective of the current study was to assess whether the NSAID-binding site can be used to regulate sulfuryl transfer in humans in an isoform specific manner. Mefenamic acid (Mef) is a potent (K_i 27 nM) NSAID-inhibitor of SULT1A1 - the predominant SULT isoform in small intestine and liver. Acetaminophen (APAP), a SULT1A1 specific substrate, is extensively sulfonated in humans. Dehydroepiandrosterone (DHEA) is specific for SULT2A1, which we show here is insensitive to Mef inhibition. APAP and DHEA sulfonates are readily quantified in urine and thus the effects of Mef on APAP and DHEA sulfonation could be studied non-invasively. Compounds were given orally in a single therapeutic dose to a healthy, adult male human with a typical APAP-metabolite profile. Mef profoundly decreased APAP sulfonation during first pass metabolism and substantially decreased systemic APAP sulfonation without influencing DHEA sulfonation; thus, it appears the NSAID site can be used to control sulfonation in humans in a SULT-isoform specific manner.