Intraoperative loading attenuates nausea and vomiting of tramadol patient-controlled analgesia

The Effect of Ondansetron on the Analgesic Efficacy of Tramadol in Patients Undergoing Laparoscopic Cholecystectomy

Purpose

Investigating the effect of ondansetron on the efficacy of tramadol in patients undergoing laparoscopic cholecystectomy.

Methods

Sixty American Society of Anesthesiologists (ASA) I-II patients over the age of 18 who underwent laparoscopic cholecystectomy were included in this study. All patients were given 1 mg/kg tramadol intravenously (iv) during the intraoperative period. Patients were randomly assigned to receive either 4 mg ondansetron (Group O) or 2 mL saline (Group S). Postoperative tramadol consumption, pain score (NRS), intensity of nausea (NRS), presence of vomiting, consumption of rescue analgesics and antiemetics, and patient satisfaction were recorded.

Results

A total of 60 patients were enrolled in the study; five patients were excluded due to deviation from the protocol. Data from 55 patients (Group O: 28 patients, Group S: 27 patients) were evaluated in the study. No differences between the two groups were detected for postoperative consumption of tramadol, pain score (NRS), intensity of nausea (NRS), presence of vomiting, consumption of rescue analgesics and antiemetics, and patient satisfaction.

Conclusions

The results showed that coadministration of tramadol and ondansetron did not change tramadol consumption during the postoperative 24 hours after laparoscopic cholecystectomy. Clinical trial registration number is as follows: https://clinicaltrials.gov/ct2/show/NCT04745273-01/31/2021.

The Routes of Administration for Acute Postoperative Pain Medication

Effective treatment of postoperative acute pain, together with early mobilization and nutrition, is one of the perioperative strategies advocated to improve surgical outcome and reduce the costs of hospitalization. Moreover, adequate pain control reduces perioperative morbidity related to surgical stress and can also prevent the incidence of chronic postoperative pain syndromes, whose treatment is still a challenge. The choice of the most appropriate analgesics depends not only on the drug class, but also on the most suitable route of administration, the best dosage for that route, and unique limitations and contraindications for every patient. In the present review, a comprehensive analysis was performed on the different routes of administration of acute postoperative pain medications and their indications and limitations, focusing on recent evidence and international recommendations.

Outpatient multimodal intravenous analgesia in patients undergoing day-case surgery: description of a three year experience

Background

The use of elastomeric devices for ambulatory intravenous pain treatment in Major Ambulatory Surgery (MAS) has been described to improve postoperative pain management. The objective of the study was to describe the first 3 years experience of the use of elastomeric devices for ambulatory intravenous pain treatment in MAS implemented at our site since 2010.

Methods

Data were retrieved from the medical records for all patients who, between January 2010 and March 2014, underwent surgical procedures at the ambulatory surgical centre at our hospital and were prescribed a home-based continuous intravenous analgesia.

Results

Data were retrieved from the medical records of 1128 patients. The most frequent surgical interventions included orthopedic and proctology surgeries. 80 % of patients were discharged home without pain; during the first 48 h after discharge roughly 40 % of subjects were completely free of pain, 50 % reported mild pain (VAS 1 to 3) and 9 % reported higher pain scores (4 and above). Peripheral nerve block was associated to better pain control in the immediate postoperative period. Vomiting in the first 24 h was 4.6 % before introducing haloperidol into the drug schemes, and 2.6 % thereafter. Complications related with the intravenous route required treatment withdrawal in 1.1 % cases. Only 3.5 % of patients returned to the hospital in the first 72 h, mainly for non-pain related reasons. Overall, 99.5 % of patients were satisfied with the treatment received at home.

Conclusion

Our initial experience suggest that outpatient multimodal intravenous analgesia in patients undergoing day-case surgery is a feasible alternative in our setting, that allows an effective management of postoperative pain with a small rate of adverse events and complications requiring readmission.

Effect of Analgesia Administration Timing on Early Post-operative Period Characteristics: A Randomized, Double-blind, Controlled Study

This study investigated the effect of time of analgesia administration in 64 patients undergoing total abdominal hysterectomy. Patients received standard general anaesthesia and were divided randomly into two equal groups. At the time of fascia closure, patients in the intra-operative (Iop) group received 0.5 mg/kg pethidine intravenously. On arrival in the post-anaesthesia care unit, the same dose of pethidine was given to patients in the post-operative (Pop) group. All patients then used a patient-controlled analgesia pump to administer pethidine analgesia as required. Times to extubation, response to verbal stimulation and orientation, post-operative pain scores and analgesic consumption were recorded. Times to extubation and response to verbal stimulation were significantly longer in the Iop group. Pain scores, analgesic consumption and additional analgesic requirements were significantly higher in the Pop group in the first 2 h post-operatively. In conclusion, intra-operative administration of pethidine provided better pain management than post-operative administration.

Effect of the CYP2D6 gene polymorphism on postoperative analgesia of tramadol in Han nationality nephrectomy patients

OBJECTIVE

Tramadol is a synthetic opioid which has analgesic efficacy in the postoperative pain. It is metabolized by polymorphic enzyme cytochrome P450 (CYP2D6). Patients with different CYP2D6 genotypes would have different responses to tramadol in pain relief. The CYP2D6*10 allele is the most common allele in a Chinese population. The aim of this study was to evaluate whether the different CYP2D6*10 genotypes have an effect on the postoperative tramadol analgesia in the Chinese population after elective nephrectomy.

METHODS

One hundred and twenty patients after performed elective nephrectomy were enrolled in this study after being approved by the local Ethics Committee. The patients were given patient-controlled analgesia (PCA) which included 10 mg/ml tramadol after receiving a loading dose of 100 mg tramadol and 1 mg granisetron intravenously. Blood samples were collected after induction of anesthesia. The CYP2D6*10 polymorphism was analyzed by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). According to the results, the patients were divided into three groups (CYP2D6*1/*1, n = 33; CYP2D6*1/*10, n = 28; CYP2D6*10/*10, n = 50). The total consumption of tramadol, visual analogue scale (VAS) score, and PCA control times among the three genotype groups for 2, 4, 24, 48, and 72 h after operation were compared.

RESULTS

Nine out of 120 patients were dropped out of the study; 111 patients completed the study. The frequency of CYP2D6*10 allele was 57.7%. The demographic data among the three groups were comparable. The consumption of tramadol, patient self-control times of pump, and VAS score in CYP2D6*10/*10 group were significantly higher than that in CYP2D6*1/*1 or CYP2D6*1/*10 group at 2 and 4 h (P < 0.05), while it did not differ between CYP2D6*1/*1 and CYP2D6*1/*10 group (P > 0.05). There was no difference in the incidence of nausea and vomiting among the three groups (P > 0.05). No sever apnea was recorded in these groups.

CONCLUSIONS

Different CYP2D6*10 genotypes have an influence on the analgesic effect of tramadol in Han nationality patients after elective nephrectomy.

Pre-emptive triple analgesia protocol for tonsillectomy pain control in children: double-blind, randomised, controlled, clinical trial

Introduction:

This double-blind, controlled, parallel-group study was designed to determine the efficacy of pre-emptive triple analgesia for paediatric post-tonsillectomy pain management.

Materials and methods:

One hundred and thirty-five children were randomised into two groups: pre-emptive triple analgesia (n = 55) and control (n = 80). Pain was assessed using a visual analogue scale (in hospital) and the Parent's Postoperative Pain Measure (at home), and scores recorded.

Results:

Visual analogue scale scores on awakening and for 6 hours post-surgery were significantly better in the study group than the control group (p < 0.05). The Parent's Postoperative Pain Measure scores of control group children were significantly higher within the first 3 post-operative days (p = 0.000), with a greater percentage of children experiencing significant pain and requiring more analgesia.

Conclusion:

The proposed multimodal, pre-emptive analgesia protocol for paediatric post-tonsillectomy pain results in less post-operative pain, both in hospital or at home.

Estimation of the minimum effective dose of tramadol for postoperative analgesia in infants using the continual reassessment method

Tramadol is a potent analgesic. However, the analgesia efficacy of tramadol, particularly its minimum effective dose (MED), is not clear. The aim of this study is to find MED of tramadol for postoperative analgesia in infants. The continual reassessment method (CRM) was performed to find MED. Infants undergoing surgeries were included in the 3 phases of this series. In each phase, 24 participants were allocated a different tramadol dose. Pain intensity was measured by face, legs, activity, cry, consolability (FLACC) measurement at 3-hour intervals. Tramadol was considered ineffective if the FLACC score was higher than 4 in 10 at anytime. In phase 1, seven dose levels were used within the range 0.1-0.4 mg·kg(-1)·h(-1). Phase 1 was insufficient to identify the MED, and we increased the dose to 0.4-0.8 mg·kg(-1)·h(-1) in phase 2. Phase 2 was insufficient to identify the MED. In phase 3, local anesthetic wound infiltration was introduced, and the tramadol dose levels tested were the same as in phase 1. The successful analgesia probability of tramadol 0.4 mg·kg(-1)·h(-1) was 82.1% (95% CI, 0.742-0.925) in phase 1. In phase 2, it was 84.7% (95% CI, 0.789-0.991) with the dose 0.8 mg·kg(-1)·h(-1). Phase 1 and phase 2 were insufficient to identify the MED. In phase 3, the successful analgesia probability for dose 0.35 mg·kg(-1)·h(-1) was 96.7% (95% CI, 0.853-0.997).We have demonstrated that tramadol provides insufficient analgesia for surgeries considered to cause moderate-to-severe postoperative pain in infants if used as the sole analgesic, and that local anesthetic wound infiltration enhances the efficacy of tramadol.

The efficacy of intravenous paracetamol versus tramadol for postoperative analgesia after adenotonsillectomy in children

STUDY OBJECTIVE

To evaluate the efficacy and the quality of recovery with intravenous (IV) paracetamol versus tramadol for postoperative analgesia after adenotonsillectomy in children.

DESIGN

Prospective, randomized, double-blinded clinical trial.

SETTING

Operating room and Postanesthesia Care Unit (PACU) of a university-affiliated hospital.

PATIENTS

64 ASA physical status I and II children, aged 6 to 16 years, scheduled for adenotonsillectomy.

INTERVENTIONS

All patients were premedicated with oral midazolam 0.5 mg/kg 30 minutes before surgery. Patients were randomized to two groups following induction of general anesthesia. The paracetamol group (n = 32) received 15 mg/kg of IV paracetamol and the tramadol group (n = 32) received 1.0 mg/kg of IV tramadol.

MEASUREMENTS

Modified Hannallah pain scores, emergence agitation, Aldrete scores, sedation scores, time to first administration of analgesic, heart rate, and mean arterial blood pressure were recorded for each patient. Data were recorded every 5 minutes for the first 30 minutes and every 10 minutes for the remaining 30 minutes in the PACU, then at 2, 3, 4, 5, 6, 8, 12, and 24 hours in the ward. The frequency of postoperative nausea and vomiting also was noted. Satisfaction of parents and nurses was determined on a 4-point scale at the end of the study.

MAIN RESULTS

No significant demographic differences between groups were noted. No statistically significant difference was found in postoperative pain scores in either group. Agitation scores, Aldrete scores, sedation scores, and number of patients who received rescue analgesia and time to administration of rescue analgesia were similar in both groups.

CONCLUSIONS

The IV formulation of paracetamol was associated with similar analgesic properties and early recovery to that of IV tramadol after adenotonsillectomy in children.

Preoperative tramadol combined with postoperative small-dose tramadol infusion after total abdominal hysterectomy: a double-blind, randomized, controlled trial

This double blind, randomized, controlled trial investigated whether a single preoperative intravenous (iv) dose of tramadol (100 mg) given 30 min before abdominal hysterectomy resulted in improved analgesic efficacy, reduced postoperative morphine patient-controlled analgesia (PCA) use and reduced side effects when combined with a postoperative small-dose tramadol infusion. Two-hundred twenty-four patients undergoing elective abdominal hysterectomy were randomly allocated to one of two groups: the tramadol group (n = 113) received iv tramadol (100 mg) 30 min before surgery, and the control group (n = 111) received an equivalent volume of normal saline. Upon awakening from general anesthesia, all patients received a loading dose of 0.5 mg/kg of tramadol and a small-dose infusion of tramadol (0.1 mg/kg/h) for 48 h. In addition, all patients were connected to morphine PCA delivering a morphine bolus of 0.02 mg/kg with a 6-min lock-out. Data on pain intensity at rest and during movement, morphine consumption, side-effects and overall patient satisfaction were recorded. A total of 189 patients completed the study. Preemptive tramadol was associated with superior analgesia at rest and with movement in the first 24 h after surgery (p < 0.01), a longer interval to first morphine PCA request (p = 0.019), and reduced morphine PCA use (p = 0.017). The tramadol group had reduced nausea (p = 0.015), dizziness (p = 0.001) and drowsiness (p = 0.0001), while other side-effects were similar. In conclusion, a single dose of iv tramadol (100 mg) 30 min prior to abdominal hysterectomy improves analgesia, and reduces morphine PCA requirements, nausea, dizziness and drowsiness when combined with a postoperative small-dose tramadol infusion and morphine PCA when compared to the same analgesic regimen that omitted the preemptive tramadol.

Effect of tramadol on bispectral index during anesthesia with desflurane

BACKGROUND

This study is aimed to investigate the effect of tramadol on the bispectral index (BIS) during anesthesia with desflurane.

METHODS

One hundred fifty adults, ASA class 1 and 2 patients, scheduled for general anesthesia for elective surgical procedures were included in this study. None of the patients were premedicated and anesthesia was induced with propofol 2 mg/kg and maintained with air-oxygen (FiO2 0.5) and desflurane, adjusted to keep the BIS between from 50 and 60. Forty minutes before completing surgery, the subjects were randomly allocated into 3 groups to receive saline (control group), tramadol 1.5 mg/kg (T1 group) or 3.0 mg/kg (T2 group) intravenously. Hemodynamics and BIS values were then recorded every 5 minutes until completion of the operation, during which time the concentrations of desflurane were not modified.

RESULTS

The mean BIS values after tramadol administration weren't significantly different from the control group throughout the period of observation. No significant changes in the hemodynamics were noted, except systolic and diastolic arterial blood pressure in the T1 and T2 groups significantly increased in the first 5 minutes after the tramadol injection.

CONCLUSIONS

The results indicate that the administration of tramadol while maintaining anesthesia with desflurane, adjusted to keep the BIS between 50 and 60, does not modified BIS values. So, we propose that tramadol can be safely administered as an immediate postoperative analgesia without concern about intra-operative awareness.

Tramadol for pain relief in children undergoing adenotonsillectomy: a comparison with dextromethorphan

OBJECTIVE/HYPOTHESIS

Establishment of good analgesia is of major concern in the postoperative period after adenotonsillectomy. The aim of this study was to compare the effects of dextromethorphan and tramadol on postoperative pain after adenotonsillectomy in children.

STUDY DESIGN

Randomized study.

METHODS

Ninety ASA class I, II (children age, 4-10 years) scheduled for adenotonsillectomy were randomized into three groups to receive placebo syrup (control group), 1 mg/kg dose of dextromethorphan cough syrup oral (Dex group) or oral placebo syrup (Tramadol group), 30 minutes before arrival in the operating room. Then during induction of anesthesia group control received 0.9% physiological saline, group Dex received 0.9% physiological saline, group Tramadol (1 mg/kg) of tramadol hydrochloride intravenously, in a total volume of 4 mL. Postoperative analgesic requirements and side effects were recorded. Pain was assessed by face scale every hour up to 6 hours postop.

RESULTS

There were no statistically significant differences in age, weight, and sex between groups (P > .05). There were statistically significant differences in, pain scores in first time postoperatively and further analgesic requirements (P < .05). All patients in placebo group (100%), two patients in the tramadol group (6.6%), and nine patients in dextromethorphan group (40%) required supplementary meperidine in recovery room. The incidence of nausea and vomiting was 5.5% in the Dextromethorphan group, 10% in the tramadol group, 6.6% in the control group; there was no significant difference between the groups (P > .05).

CONCLUSIONS

Intravenous tramadol (1 mg/kg) is more suitable than 1 mg/kg dose of dextromethorphan cough syrup oral in reducing posttonsillectomy pain in children.

Concentrations of tramadol and O-desmethyltramadol enantiomers in different CYP2D6 genotypes

The influence of CYP2D6 genotype and CYP2D6 inhibitors on enantiomeric plasma levels of tramadol and O-desmethyltramadol as well as response to tramadol was investigated. One hundred and seventy-four patients received one hundred intravenous tramadol 3 mg/kg for postoperative analgesia. Blood samples drawn 30, 90, and 180 min after administration were analyzed for plasma concentrations of the enantiomers (+)-, (-)tramadol and (+)-, (-)O-desmethyltramadol by liquid chromatography-tandem mass spectrometry. Different CYP2D6 genotypes displaying zero (poor metabolizer (PM)), one (heterozygous individual (HZ)/intermediate metabolizer (IM)), two extensive metabolizer (EM), and three (ultra rapid metabolizer (UM)) active genes were compared. Concentrations of O-desmethyltramadol differed in the four genotype groups. Median (1/3 quartile) area under the concentration-time curves for (+)O-desmethyltramadol were 0 (0/11.4), 38.6 (15.9/75.3), 66.5 (17.1/118.4), and 149.7 (35.4/235.4) ng x h/ml for PMs, HZ/IMs, EMs, and UMs (P<0.001). Comedication with CYP2D6 inhibitors decreased (+) O-desmethyltramadol concentrations (P<0.01). In PMs, non-response rates to tramadol treatment increased fourfold compared with the other genotypes (P<0.001). In conclusion, CYP2D6 genotype determined concentrations of O-desmethyltramadol enantiomers and influenced efficacy of tramadol treatment.

Intravenous magnesium sulphate decreases postoperative tramadol requirement after radical prostatectomy*

BACKGROUND

The purpose of this study was to assess whether the addition of intravenous magnesium sulphate (Mg) at the induction of anaesthesia to a balanced anaesthetic protocol including wound infiltration, paracetamol and tramadol resulted in improved analgesic efficiency after radical prostatectomy.

METHODS

We conducted a randomized, double-blind, controlled study. Thirty ASA I or II males scheduled to undergo radical retropubic prostatectomy with general anaesthesia were prospectively assigned to one of the two groups (n = 15 each). The Mg group (Gr Mg) received 50 mg kg-1 of MgSO4 in 100 mL of isotonic saline over 20 min immediately after induction of anaesthesia and before skin incision. The patients in the control group (Gr C) received the same volume of saline over the same period. At the time of abdominal closure, wound infiltration with 190 mg (40 mL) of ropivacaine was performed in both groups. Pain was assessed by a 10-point visual analogue scale in the recovery room starting from the time of tracheal extubation. Standardized postoperative analgesia included paracetamol and tramadol administered via a patient-controlled analgesia device.

RESULTS

In the postoperative period, both groups experienced an identical pain course evolution. Cumulative mean tramadol dose after 24 h was 226 mg in the magnesium group and 446 mg in the control group (P < 0.001). Postoperative nausea occurred in two patients in each group. Two vs. eight patients required analgesic rescue in magnesium and control groups, respectively (P = 0.053).

CONCLUSIONS

This study shows that intravenous magnesium sulphate reduces tramadol consumption when used as a postoperative analgesic protocol in radical prostatectomy.

A comparison of postoperative cognitive function and pain relief with fentanyl or tramadol patient-controlled analgesia

STUDY OBJECTIVE

The use of different opioids for patient-controlled analgesia (PCA) may affect postoperative cognitive function differently. Patient-controlled analgesia fentanyl has been shown to preserve cognitive function better than morphine. The effect of PCA tramadol on cognitive function is unknown. This study aims to compare postoperative cognitive function and analgesia of PCA fentanyl or tramadol.

DESIGN

Prospective randomized double-blinded study.

SETTING

Metropolitan teaching hospital.

PATIENTS

30 ASA physical status I, II, and III patients undergoing lower abdominal operations.

INTERVENTIONS

Patients received standard general anesthesia for their operations. Postoperatively, patients received either fentanyl (group F, 10 mug bolus, n = 17) or tramadol (group T, 20 mg bolus, n = 13) for PCA. Group F patients also received fentanyl boluses and group T patients received tramadol boluses intraoperatively.

MEASUREMENTS

Cognitive function was measured using Mini-Mental State Examination and Benton Visual Retention Test (BVRT) preoperatively and on days 1 and 2. Pain was measured by numerical rating scale.

RESULTS

No differences were found in postoperative Mini-Mental State Examination or BVRT scores, but significantly fewer (29.4%; 95% confidence interval [CI], 13.3%-53.1%) group F patients were able to complete BVRT compared with group T patients (84.6%; 95% CI, 57.8%-95.7%; 95% CI of difference, 19.4%-74.8%) (P = 0.010) on day 1. In the first 24 hours, group F and group T patients had similar analgesia at rest, but group T patients had better analgesia during cough (mean Numeric Rating Scale, 7.6; 95% CI, 7.0-8.2 vs 6.0; 95% CI, 4.8-7.2, group F vs group T) (P = 0.018; 95% CI of difference, 0.4-2.8). No differences were found in frequency of side effects or patient satisfaction.

CONCLUSIONS

Tramadol or fentanyl PCA has similar cognitive effects on days 1 and 2; however, patients receiving tramadol PCA are more motivated to undergo cognitively demanding tasks and have slightly better analgesia on postoperative day 1.

Analgesic and antacid properties of i.m. tramadol given before Caesarean section under general anaesthesia

BACKGROUND

Intramuscular (i.m.) tramadol increases gastric pH during anaesthesia similar to famotidine. We investigated the antacid analgesic value of a single dose of i.m. tramadol given 1 h before elective Caesarean section performed under general anaesthesia.

METHODS

Sixty ASA I parturients undergoing elective Caesarean section were included in a randomized double-blind study. The patients were randomly allocated to receive i.m. tramadol 100 mg (n=30) or famotidine 20 mg (n=30) 1 h before general anaesthesia.

RESULTS

At the beginning and the end of anaesthesia, patients receiving tramadol had a median gastric fluid pH of 6.4, which was not significantly different from those treated with famotidine (median 6.3). The infant well-being, as judged by Apgar score, cord blood gas analysis, and neurobehavioural assessment showed no significant difference between the two groups. Nalbuphine consumption in the first 24 h after operation was reduced by 35% in the tramadol group. Pain intensity score on sitting and sedation were significantly greater in famotidine group up to 24 h after surgery. There was no significant difference in incidence and severity of nausea and vomiting between the two groups.

CONCLUSION

A single i.m. dose of tramadol is useful pre-treatment to minimize the risk of acid aspiration during operation, and in improving pain relief during 24 h after surgery.

Clinical pharmacology of tramadol

Tramadol, a centrally acting analgesic structurally related to codeine and morphine, consists of two enantiomers, both of which contribute to analgesic activity via different mechanisms. (+)-Tramadol and the metabolite (+)-O-desmethyl-tramadol (M1) are agonists of the mu opioid receptor. (+)-Tramadol inhibits serotonin reuptake and (-)-tramadol inhibits norepinephrine reuptake, enhancing inhibitory effects on pain transmission in the spinal cord. The complementary and synergistic actions of the two enantiomers improve the analgesic efficacy and tolerability profile of the racemate. Tramadol is available as drops, capsules and sustained-release formulations for oral use, suppositories for rectal use and solution for intramuscular, intravenous and subcutaneous injection. After oral administration, tramadol is rapidly and almost completely absorbed. Sustained-release tablets release the active ingredient over a period of 12 hours, reach peak concentrations after 4.9 hours and have a bioavailability of 87-95% compared with capsules. Tramadol is rapidly distributed in the body; plasma protein binding is about 20%. Tramadol is mainly metabolised by O- and N-demethylation and by conjugation reactions forming glucuronides and sulfates. Tramadol and its metabolites are mainly excreted via the kidneys. The mean elimination half-life is about 6 hours. The O-demethylation of tramadol to M1, the main analgesic effective metabolite, is catalysed by cytochrome P450 (CYP) 2D6, whereas N-demethylation to M2 is catalysed by CYP2B6 and CYP3A4. The wide variability in the pharmacokinetic properties of tramadol can partly be ascribed to CYP polymorphism. O- and N-demethylation of tramadol as well as renal elimination are stereoselective. Pharmacokinetic-pharmacodynamic characterisation of tramadol is difficult because of differences between tramadol concentrations in plasma and at the site of action, and because of pharmacodynamic interactions between the two enantiomers of tramadol and its active metabolites. The analgesic potency of tramadol is about 10% of that of morphine following parenteral administration. Tramadol provides postoperative pain relief comparable with that of pethidine, and the analgesic efficacy of tramadol can further be improved by combination with a non-opioid analgesic. Tramadol may prove particularly useful in patients with a risk of poor cardiopulmonary function, after surgery of the thorax or upper abdomen and when non-opioid analgesics are contraindicated. Tramadol is an effective and well tolerated agent to reduce pain resulting from trauma, renal or biliary colic and labour, and also for the management of chronic pain of malignant or nonmalignant origin, particularly neuropathic pain. Tramadol appears to produce less constipation and dependence than equianalgesic doses of strong opioids.

Impact of CYP2D6 genotype on postoperative tramadol analgesia

Genetic polymorphisms result in absent enzyme activity of CYP2D6 (poor metabolizers, PM) in about 10% of the Caucasian population. This study investigates whether the PM genotype has an impact on the response to tramadol analgesia in postoperative patients. A prospective study design was used and 300 patients recovering from abdominal surgery were enrolled. After titration of an individual loading dose, patients could self-administer 1 ml bolus doses of the drug combination tramadol 20 mg/ml, dipyrone 200 mg/ml and metoclopramide 0.4 mg/ml via patient-controlled analgesia (PCA). Patients' genotype was analyzed considering the most prevalent PM associated CYP2D6 mutations using a real-time PCR and hybridization based genotyping method. Demographic data, surgery related variables, pain scores, analgesic consumption and need for rescue medication were compared between extensive metabolizers (EM) and PM. The primary outcome criterion 'response' was defined as responder or non-responder status by the need for rescue medication and patients' satisfaction at the final interview. Demographic and surgery related data were comparable between EM (n=241) and PM (n=30). The percentage of non-responders was significantly higher in the PM group (46.7%) compared with the EM group (21.6%; p=0.005). Tramadol loading dose amounted to 108.2+/-56.9 and 144.7+/-22.6 mg (p<0.001) in EM and PM, respectively. More patients displaying the PM genotype needed rescue medication in the recovery room and during PCA period than patients with at least one wild type allele (21.6 versus 43.3%, p=0.02). PM for CYP2D6 showed a lower response rate to postoperative tramadol analgesia than EM. Therefore, CYP2D6 genotype has an impact on analgesia with tramadol. Pharmacogenetics may explain some of the varying response to pain medication in postoperative patients.

Tramadol for pain relief in children undergoing tonsillectomy: a comparison with morphine

BACKGROUND

Pain control for paediatric patients undergoing tonsillectomy remains problematic. Tramadol is reported to be an effective analgesic and to have a side-effect profile similar to morphine, but is currently not licensed for paediatric use in the UK.

METHODS

We conducted a prospective, double-blind, randomized controlled trial in children who were scheduled for elective tonsillectomy or adenotonsillectomy at the Royal Aberdeen Children Hospital. Following local ethics committee approval and after obtaining a drug exemption certificate from the Medicines Licensing Agency for an unlicensed drug, we recruited 20 patients each into morphine (0.1 mg.kg(-1)), tramadol (1 mg.kg(-1)) and tramadol (2 mg.kg(-1)) groups. These drugs were given as a single injection following induction of anaesthesia. In addition, all patients received diclofenac (1 mg.kg(-1)) rectally. The postoperative pain scores, analgesic requirements, sedation scores, signs of respiratory depression and nausea and vomiting, as well as antiemetic requirements, were noted at 4-h intervals until discharge.

RESULTS

There were no statistically significant differences in age, weight, type of operation or induction of anaesthesia, 4-h sedation and pain scores and further analgesic requirements. There were no episodes of respiratory depression. Morphine was associated with a significantly higher incidence of vomiting following discharge to the wards (75% versus 40%, P=0.03) compared with both tramadol groups.

CONCLUSIONS

Tramadol has similar analgesic properties, when compared with morphine. The various pharmaceutical presentations and the availability as a noncontrolled substance may make it a useful addition to paediatric anaesthesia if it becomes licensed for paediatric anaesthesia in the UK.

Tramadol 2.5 mg x kg(-1) appears to be the optimal intraoperative loading dose before patient-controlled analgesia

PURPOSE

We previously established that a 5 mg x kg(-1) intraoperative dose can reduce the nausea/vomiting associated with tramadol patient-controlled analgesia (PCA). This study was conducted to identify the most appropriate initial dose to improve the quality of tramadol PCA.

METHODS

During general anesthesia, 60 patients undergoing knee arthroplasty were randomly allocated to receive 1.25 mg x kg(-1) (Group I), 2.5 mg x kg(-1) (Group II), 3.75 mg x kg(-1) (Group III), or 5 mg x kg(-1) (Group IV) tramadol. The emergence condition was recorded. The titration of additional tramadol 20 mg + metoclopramide 1 mg doses by PCA every five minutes was performed in the postanesthesia care unit (PACU) until the visual analogue scale (VAS) score was < or = 3. An investigator blinded to study group recorded the VAS and side effects every ten minutes.

RESULTS

In the PACU, significantly more tramadol (8.4 +/- 3.1 vs 4.3 +/- 2.1, 2.5 +/- 1.8, and 0.4 +/- 0.3, P < 0.05), and a higher incidence (15/15 vs 5/15, 3/15, and 2/15, P < 0.05) of PCA use was observed in Group I compared to Groups II-IV. VAS was significantly higher in Group I than in Groups II-IV at zero and ten minutes (P < 0.05). Unexpected delayed emergence anesthesia (> 30 min) was observed in Group III (n = 1) and in Group IV (n = 2). Sedation was more important in Groups III and IV than in Groups I and II (P < 0.05).

CONCLUSION

When considering efficacy and side-effect profile, 2.5 mg x kg(-1) of tramadol is the optimal intraoperative dose of this drug to provide effective postoperative analgesia with minimal sedation.

The addition of a tramadol infusion to morphine patient-controlled analgesia after abdominal surgery: a double-blinded, placebo-controlled randomized trial

In this double-blinded, randomized controlled trial, we tested whether the addition of tramadol to morphine for patient-controlled analgesia (PCA) resulted in improved analgesia efficacy and smaller morphine requirements compared with morphine PCA alone after abdominal surgery in adults. Sixty-nine patients were randomly allocated into two groups, each receiving morphine 1 mg/mL via PCA after surgery. The tramadol group received an intraoperative initial loading dose of tramadol (1 mg/kg) and a postoperative infusion of tramadol at 0.2 mg. kg(-1). h(-1). The control group received an intraoperative equivalent volume of normal saline and a postoperative saline infusion. Postoperatively, tramadol was associated with improved subjective analgesic efficacy (P = 0.031) and there was significantly less PCA morphine use in the tramadol group (P = 0.023). No differences between the groups were found with regard to nausea, antiemetic use, sedation, or quality of recovery (all P > 0.05). We conclude that a tramadol infusion combined with PCA morphine improves analgesia and reduces morphine requirements after abdominal surgery compared with morphine PCA alone.

IMPLICATIONS

In this study, we determined whether adding a second pain-killing drug, tramadol, could improve pain relief after major surgery in patients receiving morphine patient-controlled analgesia. We found that patients receiving tramadol had significantly better opinions of their pain relief and used significantly less morphine with no increase in side effects.

Metoclopramide decreases emesis but increases sedation in tramadol patient-controlled analgesia

PURPOSE

To evaluate the clinical benefits and disadvantages of adding metoclopramide to tramadol for patient-controlled analgesia (PCA).

METHODS

Forty adult patients, undergoing elective arthroplasties, were recruited into this prospective, randomized, double-blind study. During general anesthesia all patients received 2.5 mg x kg(-1) of tramadol as a loading dose at the beginning of wound closure. In the postanesthesia care unit (PACU) patients were randomly allocated to receive PCA containing either 20 mg tramadol + 1 mg metoclopramide per millilitre (n = 20, Group T+M) or tramadol 20 mg per millilitre (n = 20, Group T). The PCA setup was 1 mL/bolus with a lockout interval of five minutes. A blinded investigator assessed the vital signs, visual analogue scale, and severity of postoperative nausea and/or vomiting in the PACU. The PCA demand and delivery, overall satisfaction rate and adverse effects were recorded in the PACU and on postoperative days one and two.

RESULTS

Nausea/vomiting scores were more severe (1.7 +/- 1.0 vs 0.2 +/- 0.5, 2.3 +/- 1.2 vs 0.6 +/- 0.6, 1.9 +/- 0.9 vs 0.2 +/- 0.5, at 12 hr, 18 hr, 24 hr, respectively, P < 0.05) and more frequent (7/20 vs 1/20, 5/20 vs 0/20 for nausea and vomiting respectively, P < 0.05) on postoperative day one in Group T compared to Group T+M. However, the incidence of sedation was higher in Group T+M (7/20 vs 1/20, P < 0.05).

CONCLUSIONS

The incidence and severity of nausea/vomiting decreased if metoclopramide was added to tramadol for PCA. An increased incidence of sedation was noticed with this drug combination.