Use of intravenous acetaminophen in the treatment of postoperative pain

Individual Factors Modifying Postoperative Pain Management in Elective Total Hip and Total Knee Replacement Surgery

Total hip and knee replacements are the most common orthopedic procedures performed due to osteoarthritis. Pain is an intrinsic symptom accompanying osteoarthritis, persisting long before surgery, and continuing during the preoperative and postoperative periods. Appropriate pain management after surgery determines the comfort, duration, and cost of hospitalization, as well as the effectiveness of postoperative rehabilitation. Individual differences in pain perception and tolerance in orthopedic patients remain an important research topic. Therefore, the aim of this study was to investigate the predictors of analgesic requirements (morphine, acetaminophen, and ketoprofen), including individual pain threshold and tolerance, body mass index (BMI), diabetes, and beliefs about pain control in patients undergoing elective hip or knee arthroplasty using a multilevel regression model (N = 147, 85 women, 62 men, 107 after hip replacement, and 40 after knee replacement). Results: Higher pain tolerance was associated with a lower dose of morphine per kg after surgery. Patients undergoing hip surgery received a lower dose of ketoprofen than patients undergoing knee surgery. The more the patient believed in personal pain control, the stronger the negative relationship between pain tolerance and morphine requirement. The lowest doses were given to patients with the highest pain tolerance and the greatest belief in personal control. Factors such as belief in pain control and pain tolerance should be considered in comprehensive postoperative pain management in orthopedic patients to reduce opioid doses and, thus, side effects.

Intraoperative liposomal bupivacaine for skin graft donor site analgesia: A retrospective cohort study

INTRODUCTION

Burn injury and reconstructive operations often result in severe pain, particularly at skin graft donor sites. Traditional local anesthetics administered intraoperatively control pain at donor sites, but the duration of action is short. Liposomal bupivacaine, a novel local anesthetic, can provide sustained-release analgesia for 72h. The primary aim of this study was to describe the efficacy of liposomal bupivacaine for postoperative donor site pain control for patients undergoing skin graft procedures.

METHODS

A retrospective cohort study was performed on patients who received a donor site liposomal bupivacaine field block and was compared to a matched control. Patients rated donor site pain on post-operative day 0 and 1, and stated whether the donor or graft site was more painful.

RESULTS

Fifty-eight patients were included. Twenty-nine patients received liposomal bupivacaine. Eighty-six percent of patients in the treatment group rated donor site pain as three or less on postoperative day 0 and 1, compared to 3.4% in the control (p<0.0001). Also, 76% of patients in the treatment group stated donor site pain was less than graft site pain, compared to 3.4% in the control (p<0.0001).

CONCLUSION

Patients who received liposomal bupivacaine reported less postoperative donor site pain and found the donor site to be less bothersome without major complications. Liposomal bupivacaine may be a safe and promising agent for prolonging postoperative analgesia and minimizing donor site pain.

A prospective randomized trial of intravenous ketorolac vs. acetaminophen administered with opioid patient-controlled analgesia in gynecologic surgery

OBJECTIVE

To determine which non-narcotic analgesic, acetaminophen (Ofirmev®) or ketorolac (Toradol®), provides better post-operative pain control when combined with an opioid patient-controlled analgesia (PCA) pump. Secondary objectives include comparisons of the rates of ileus, post-operative bleeding, transfusions, and length-of-hospitalization (LOH).

METHODS

A prospective, randomized trial of acetaminophen (A) 1-g intravenous (IV) every 6-h or ketorolac (K) 15-mg IV every 6-h from post-operative day 1-3 in addition to an opioid PCA for patients undergoing benign or malignant gynecologic laparotomy procedures was performed. Abstracted data included pain levels via visual analogue pain scales (VAS), amount of narcotic used, hepatic enzyme levels, hemoglobin, urine output, blood transfusions, time to return of flatus and LOH.

RESULTS

One-hundred patients were accrued and underwent 55 benign gynecologic laparotomies and 45 cancer-related laparotomies. VAS pain levels (3.3 K, 3.5 A) and morphine PCA use (79.1 oral morphine equivalents [OME] K vs. 84.5 A) were not different, however dilaudid PCA usage was less by K patients (84.4 OME K and 136.8 OME A, p < 0.001). There was a significant hemoglobin change between the two groups (2.6 g K vs. 2 g A, p = 0.015), however blood transfusions were equal (28% K, 22% A, p > 0.05). Return of flatus was 2.7-days for K vs. 3.4-days for A (p = 0.011) and LOH was not different (4.4-days K vs. 5.1-days A, p = 0.094).

CONCLUSIONS

Both intravenous ketorolac and acetaminophen provide similar post-operative analgesia through VAS pain scales and total usage of morphine via PCA pumps. Use of ketorolac with dilaudid PCA was associated with less dependence on dilaudid and a quicker return of bowel function than acetaminophen, however length of stay and transfusion rates were not different.

Intraoperative Single-Dose Intravenous Acetaminophen for Postoperative Analgesia After Skin Laser Irradiation Surgery in Paediatric Patients: A Small Prospective Study

Objective

Acetaminophen is an analgesic that shows efficacy in postoperative pain relief in children. Many drugs such as opioids, non-steroidal anti-inflammatory drugs, and/or acetaminophen have been used in paediatric skin laser irradiation surgery for postoperative pain relief. However, acetaminophen has some advantages over opioids, and opioids are being used less often. We aimed to demonstrate the effectiveness of intravenous (IV) acetaminophen during surgery for postoperative pain in paediatric skin laser irradiation.

Methods

The present study is a small, prospective, double-blinded, randomized controlled trial. Paediatric patients (1-12 years old with an American Society of Anesthesiologists physical Status I and II), scheduled for skin laser irradiation for a nevus or haemangioma between October 2014 and April 2016 were randomized into the acetaminophen (n=9) and placebo (saline, n=8) groups. The observational face scale (FS) and the Behavioural Observational Pain Scale (BOPS) scores were recorded on emergence from anaesthesia, and 1, 2, and 4 hr post-surgery.

Results

Patient characteristics were not significantly different except with regard to the irradiation area and surgery time. The observational FS and BOPS scores of the acetaminophen group were lower than those of the placebo group; median (minimum-maximum) at each recording time: 1 (0-2) - 0 (0-2) - 0 (0-1) - 0 (0-2) vs. 2 (0-4) - 0 (0-2) - 0 (0-2) - 0 (0-1) and 1 (0-3) - 1 (0-3) - 1 (0-2) - 0 (0-1) vs. 2 (0-4) - 3 (0-5) - 1 (0-4) - 0 (0-3), p=0.07 and p=0.003, respectively. No differences in post-surgical analgesic use or adverse events were observed.

Conclusion

In this study, we showed that the IV acetaminophen group had lower observational FS and BOPS scores in the early postoperative period; however, further studies including a large number of patients are required to confirm our findings.

Intravenous Acetaminophen For the Management of Pain During Vaso-occlusive Crises in Pediatric Patients

BACKGROUND

Children with sickle cell disease experience vaso-occlusive crises (VOC) that requires opioid pharmacotherapy. Multimodal analgesic therapy may reduce pain and opioid-induced adverse effects.

OBJECTIVE

The primary objective was to examine the effectiveness of intravenous (IV) acetaminophen in children presenting with pain from VOC. Secondary objectives were to document the safety and opioid-sparing effects of IV acetaminophen during VOC in pediatric patients.

SETTING

Children's Medical Center, NYU-Winthrop Hospital.

METHOD

This retrospective study had two groups of patients, those who received opioids alone (group O) and those who received acetaminophen with opioids (group OA). Children two to 19 years of age who were admitted to the children's medical center for VOC were eligible for inclusion.

MAIN OUTCOME MEASURE

A reduction in pain by at least 1 out of 10. With every analgesic dose, we documented pain scales and pain scores before and after each dose, the number of doses administered per day, and mg/kg/day. Data were analyzed using the mixed effect model. All opioids administered to patients were converted to morphine equivalents. We documented length of stay and adverse events.

RESULTS

We had a total of 46 children: 28 in group O and 18 in group OA. Acetaminophen reduced the pain from VOC by 2.3/10. There were trends in different assessments of opioid-sparing effects, in reducing opioid dosage (-0.5 mg/kg morphine equivalent; P = 0.45), reducing overall morphine equivalent doses (-18.5 mg; P = 0.066), and opioid-related adverse effects.

CONCLUSION

This is the first study to demonstrate the effectiveness of IV acetaminophen in treating VOC pain in children, supporting multimodal analgesic therapy in this setting. Opioid-sparing effects were also encouraging.

A new postoperative pain management (intravenous acetaminophen: Acelio®) leads to enhanced recovery after esophagectomy: a propensity score-matched analysis

PURPOSES

To investigate the efficacy of postoperative scheduled intravenous acetaminophen to reduce the opioid use and enhance the recovery after esophagectomy.

METHODS

A propensity score-matched population was created using the 93 and 69 consecutive patients who underwent esophagectomy for esophageal cancer before and after the introduction of postoperative scheduled intravenous acetaminophen, and the short-term clinical outcomes were compared.

RESULTS

Significant defervescence was demonstrated in the Acetaminophen group (A-group) compared with control group (C-group) during the perioperative period (p < 0.05), whereas no significant differences were observed in the postoperative inflammatory parameters. The incidence of postoperative complications was similar between the groups. The number of PCA pushes and the frequency of using other non-opioid analgesics were significantly smaller in the A-group than in the C-group (p < 0.05). Both daily and cumulative opioid uses were significantly smaller in the A-group than in the C-group (p < 0.05). The time to first flatus was significantly shorter in the A-group than in the C-group (p < 0.001). The day of first walking after surgery was significantly earlier in the A-group than in the C-group (1.0 versus 2.0 days, p = 0.003). The ICU stay (2.86 versus 3.61 days, p < 0.001) and the hospital stay (21.5 versus 26.0 days, p = 0.061) tended to be shorter in the A-group than in the C-group.

CONCLUSIONS

Postoperative scheduled intravenous acetaminophen decreased the rate of opioid use without increasing the intensity of postoperative pain and may be a feasible new pain management option in the enhanced recovery after surgery protocol following esophagectomy.

Randomized controlled trial of intravenous acetaminophen for postcesarean delivery pain control

BACKGROUND

Cesarean delivery is a common surgery in the United States, with 1.3 million performed during 2009.¹ Obstetricians must balance the growing concern with opioid abuse, dependence, and side effects with optimal postoperative pain control. Intravenous acetaminophen may represent an additional method to decrease the reliance on opioid medications and improve postoperative pain following cesarean delivery.

OBJECTIVE

The objective of the study was to determine whether the administration of intravenous acetaminophen following routine scheduled cesarean delivery would decrease the need for narcotic medications to control postoperative pain.

STUDY DESIGN

This was an institutional review board-approved, double-blind, placebo-controlled, randomized trial, registered on clinicaltrials.gov (number 02046382). Women scheduled to undergo cesarean delivery with regional anesthesia at term were recruited. All perioperative and postpartum care was standardized via study order sets. Study patients were given all medications in a standardized manner receiving either acetaminophen 1000 mg intravenously or 100 mL saline (placebo) every 8 hours for 48 hours for a total of 6 doses. The pharmacy prepared intravenous acetaminophen and saline in identical administration bags labeled study drug to ensure blinding. The initial dose of study drug was given within 60 minutes of skin incision. Quantity of breakthrough and scheduled analgesic medications and self-reported pain levels on the Faces Pain Scale (0-10) before and after study drug administration were collected. Patient demographics were extracted from the chart. Power calculation determined that 45 patients per arm were required to detect a 30% reduction in postcesarean narcotic requirement with 80% power and a significance level of P = .05.

RESULTS

A total of 133 patients were consented for the study. Twenty-nine were excluded and 104 patients completed the study: 57 received intravenous acetaminophen and 47 received placebo. There were no differences in baseline demographic characteristics including patient age, body mass index, gravidity, parity, race, comorbidities, or number of prior cesarean deliveries. There were no differences between groups in estimated blood loss or length of stay. The total amount of oral narcotic medications consumed by patients receiving intravenous acetaminophen was significantly reduced when compared with the placebo group (47 mg vs 65 mg of oxycodone; P = .034). The total amount of ibuprofen used between groups was not different. There was no difference in pain scores between groups before and after study dose administration. There was no significant difference in narcotic side effects (nausea/emesis, respiratory depression, constipation) in either study arm.

CONCLUSION

Intravenous acetaminophen in the postoperative period following cesarean delivery resulted in a significant decrease in oral narcotic consumption for pain control.

Randomized Trial of Adding Parenteral Acetaminophen to Prochlorperazine and Diphenhydramine to Treat Headache in the Emergency Department

Introduction

Headaches represent over three million emergency department (ED) visits per year, comprising 2.4% of all ED visits. There are many proposed methods and clinical guidelines of treating acute headache presentations. However, data on intravenous acetaminophen usage in these settings are lacking. In this study, we sought to determine the efficacy of intravenous (IV) acetaminophen as an adjunct to a standard therapy for the treatment of patients who present to the ED with a chief complaint of “headache.”

Methods

We conducted a single site, randomized, double-blind, placebo-controlled trial investigating the clinical efficacy of IV acetaminophen as an adjunct to a standard therapy with prochlorperazine and diphenhydramine for the treatment of patients who present to the ED with a chief complaint of “headache” or variants thereof. (See below for variants). The primary outcome measure of the efficacy of parenteral acetaminophen as an adjunct treatment for headache in addition to a standard therapy was a threshold two-point reduction in visual analog scale (VAS) pain scores on a 1–10 level at 90 minutes. Secondary outcomes measures included assessment of decreased requirement of “rescue” pain medicines, defined as any analgesic medications outside of diphenhydramine, prochlorperazine and acetaminophen, with particular interest to potential opioid-sparing effects with parenteral acetaminophen. Additional secondary outcome measure included time to disposition from arrival in the ED.

Results

For the acetaminophen group the initial mean pain score was 8.67, for the placebo group 8.61. At 90 minutes pain score was 2.23 for the acetaminophen group and 3.99 for placebo (p<0.01, 95% confidence interval (CI) [0.8%–16%]. Of 45 patients in each group, we observed at least a threshold two-point decrease in pain score 36/45 (80%) with acetaminophen vs. 25/45 (55%) with placebo (p <0.01) 95% CI [5%–41%], number needed to treat (NNT) = 4). Secondary outcome measure did not demonstrate a difference in length of stay (161 minutes for acetaminophen arm and 159 minutes for placebo). However, 17/45 (38%) of patients who received IV acetaminophen required rescue analgesia, opposed to 24/45 (53%) of patients in the placebo group (p=0.13) 95% CI [−5%–34%].

Conclusion

IV acetaminophen when used with prochlorperazine and diphenhydramine to treat acute headaches in the ED resulted in statistically significant pain reduction compared with prochlorperazine and diphenhydramine alone as measured by both threshold of lowering VAS pain score by at least two points (NNT = 4) and overall decline in VAS pain score. Further study is required to validate these results.

Effectiveness of postoperative intravenous acetaminophen (Acelio) after gastrectomy: A propensity score-matched analysis

The aim of this study was to investigate the efficacy of postoperative scheduled intravenous acetaminophen to reduce the opioid use and enhance recovery after gastrectomy.Opioid use is reportedly associated with delayed recovery of gastrointestinal (GI) peristalsis and postoperative nausea/vomiting (PONV) despite of acceptable efficacy for pain control.Of 147 and 96 consecutive patients who underwent gastrectomy for gastric cancer before and after introduction of postoperative scheduled intravenous acetaminophen, propensity score matched population was created and short-term clinical outcomes were compared.Significant defervescence was demonstrated in Acetaminophen group (A-group) compared with control group (C-group) during the perioperative period (P < 0.001), whereas no significant difference was observed in postoperative inflammatory parameters. The incidence of postoperative complications was similar between the groups. The number of patient-controlled analgesia (PCA) pushes was significantly reduced in the A-group (P = 0.007) and the frequency of use of other nonopioid analgesics was also significantly reduced in the A-group (P < 0.001). Both daily and cumulative opioid use was significantly reduced in the A-group (P < 0.001). The time to first flatus and defecation was decreased in the A-group (P < 0.001 and P = 0.038, respectively). The incidence of PONV was significantly reduced from 26.0% to 12.5% after introduction of intravenous acetaminophen (P = 0.017), and hospital stay tended to be decreased in the A-group (13.2 vs 14.7 days, P = 0.069)Postoperative scheduled intravenous acetaminophen decreased opioid use and may be associated with enhanced recovery after gastrectomy.

Clinical utility of an undersized nurse-operated recovery room in the postoperative course: results from an Italian community setting

PURPOSE

In Europe, standardized criteria for recovery room (RR) requirements have not been established. The purpose of this study was to examine the clinical utility of an undersized nurse-operated RR in an Italian community hospital.

DESIGN

Single-center observational study.

METHODS

A total of 1,945 consecutive surgical patients admitted to the RR at the study institution between September 31, 2009, and August 31, 2011, were included in the study. A control group of surgical patients not admitted to the RR, matched for age, gender, American Society of Anesthesiologists score, and type of surgery were also considered. The prevalence of early adverse events occurring within 3 hours of the end of surgery was compared between the two groups.

FINDINGS

Patients admitted to the RR (mean age, 73.6 ± 14.2 years; 42.2% male; and 76.3% having major surgery) showed lower prevalences of hypotension (P < .0001), hypertensive response (P < .0001), new arrhythmias requiring intervention (P = .0036), and oxygen desaturation (P < .0001) in comparison with the control group. No differences in the proportions of patients experiencing postoperative nausea and vomiting, shivering, bleeding, and respiratory events were found. The Numeric Rating Scale for pain was also significantly lower at 2 hours in the study group as compared to the control group (1 [0 to 5] vs 3 [1 to 7]; P < .0001).

CONCLUSION

In this Italian community setting, an undersized nurse-operated RR contributed to a reduced prevalence of adverse postoperative events.

Impact of Postoperative Intravenous Acetaminophen on Opioid Requirements and Pain Scores Following Gynecologic Procedures

OBJECTIVE

This study aims to assess the impact of postoperative intravenous (IV) acetaminophen on opioid requirements and pain scores in patients following gynecologic procedures.

STUDY DESIGN

A retrospective cohort study of patients undergoing gynecologic procedures was conducted to assess the impact of adding scheduled IV acetaminophen to postoperative analgesic regimens. The control group consisted of patients admitted prior to formulary addition of IV acetaminophen; the study group consisted of patients admitted after formulary addition of IV acetaminophen who received scheduled IV acetaminophen for at least the first 24 hours postoperatively. Opioid requirements 0 to 24 hours postoperatively served as the primary end point. Secondary end points included average pain score, cumulative acetaminophen dose, nonopioid analgesic requirements, and rate of adverse events 0 to 24 hours postoperatively.

RESULTS

One hundred and thirty-seven patients who underwent a gynecologic procedure from January 2009 to April 2013 were included in this study. Baseline characteristics were similar between the groups. In the first 24 hours postoperatively, there was no difference in opioid requirements between the groups (21 mg [interquartile range, IQR, 15-39.8 mg] vs 32.6 mg [IQR, 16.75-41 mg], P = 0.150). The average pain score and incidence of adverse events did not differ between the 2 groups.

CONCLUSION

Postoperative administration of IV acetaminophen did not provide a significant opioid-sparing effect in patients undergoing gynecologic procedures.

[Paracetamol. Efficacious and safe for all ages]

Paracetamol has become a focus of attention as being unsafe due to hepatic toxicity and market withdrawal or prescription status is presently under discussion in Germany. This drug is, however, effective and safe if notes of caution are applied. In Germany 38 fatal cases of analgesic poisoning were observed in 2010, only 4 of which were due to paracetamol and 16 were caused by diclofenac and ibuprofen. Alternative pain medications are obviously much less safe, in particular given the additional risk of sometimes fatal gastrointestinal bleeding and cardiovascular side effects. This review extensively analyzes the safety record of paracetamol and applies these findings to the treatment of elderly people. Even very elderly patients may be safely treated with this compound, although a dose limit of 3 g/day should be instituted. This renewed discussion was triggered by the uncontrolled availability of paracetamol in the USA but observations from this country should not be generalized and applied to the German situation and objective reasoning should be re-installed.

Clinical pharmacology of intravenous paracetamol in perinatal medicine

Clinical pharmacology aims to predict drug-related effects based on compound and population specific pharmacokinetics (PK, concentration-time), and pharmacodynamics (PD, concentration-effect). Consequently, dosing needs to be based on the physiological characteristics of the individual patient. Pregnancy and early infancy hereby warrant focused assessment. The specific characteristics of both subpopulations will be illustrated based on observations on intravenous (iv) paracetamol PK and PD collected in these specific populations. At delivery, there is a significant higher paracetamol clearance (+ 45%, L/h) when compared to non-pregnant observations. This higher clearance is in part explained by a proportional increase in oxidative metabolite production, but mainly an increase in glucuronidation. When focusing on PD, an association between maternal paracetamol exposure and atopy in infancy and fetal gastroshizis has been reported. In early infancy, paracetamol clearance is significantly lower and mainly depends on size (weight 0.75), while also the distribution volume is higher (L/kg). Reports on hepatic tolerance, haemodynamic stability and impact of body temperature have been published while the concentration effect profile for analgesia seems to be similar between neonates and children. Similar to maternal exposure, there are reports on the association with atopy. Studies on the use of paracetamol to close the patent ductus arteriosus are ongoing. At least, these observations provide evidence on the need to study commonly administered anesthetics in such specific subpopulations with specific focus on both population specific PK and PD to further improve patient tailored pharmacotherapy.

Systemic paracetamol-induced analgesic and antihyperalgesic effects through activation of descending serotonergic pathways involving spinal 5-HT₇ receptors

Although some studies have shown the essential role of descending serotonergic pathways and spinal 5-HT(1A), 5-HT(2A), or 5-HT(3) receptors in the antinociceptive effects of paracetamol, other studies have presented conflicting results, and the particular subtype of spinal 5-HT receptors involved in paracetamol-induced analgesia remains to be clarified. Recent studies have demonstrated the importance of spinal 5-HT(7) receptors in descending serotonergic pain inhibitory pathways. In this study, we investigated the role of descending serotonergic pathways and spinal 5-HT(7) receptors compared with 5-HT(3) and 5-HT(2A) receptors in the antinociceptive and antihyperalgesic effects of paracetamol. Tail-flick, hot plate and plantar incision tests were used to determine nociception in male BALB/c mice. Lesion of serotonergic bulbospinal pathways was performed by intrathecal (i.th.) injection of 5,7-dihydroxytryptamine (5,7-DHT), and spinal 5-HT levels were measured by HPLC. To evaluate the particular subtypes of the spinal 5-HT receptors, the selective 5-HT(7), 5-HT(3) and 5-HT(2A) receptor antagonists SB 269970, ondansetron and ketanserin, respectively, were given i.th. after oral administration of paracetamol. Oral paracetamol (200, 400 and 600 mg/kg) elicits dose-dependent antinociceptive and antihyperalgesic effects. I.th. pretreatment with 5,7-DHT (50 μg) sharply reduced 5-HT levels in the spinal cord. Depletion of spinal 5-HT totally abolished the antinociceptive and antihyperalgesic effects of paracetamol. I.th. injection of SB 2669970 (10 μg) blocked the antinociceptive and antihyperalgesic effects of paracetamol, but ondansetron and ketanserin (10 μg) did not. Our findings suggest that systemic administration of paracetamol may activate descending serotonergic pathways and spinal 5-HT(7) receptors to produce a central antinociceptive and antihyperalgesic effects.