A comparative study on the analgesic effect of tramadol, tramadol plus magnesium, and tramadol plus ketamine for postoperative pain management after major abdominal surgery

PHARMACOKINETICS OF TRAMADOL AND O-DESMETHYLTRAMADOL IN GIANT TORTOISES (CHELONOIDIS VANDENBURGHI, CHELONOIDIS VICINA)

The objective of this study was to determine the pharmacokinetics of two orally administered doses of tramadol (1 mg/kg and 5 mg/kg) and its metabolite, O-desmethyltramadol (M1) in giant tortoises (Chelonoidis vandenburghi, Chelonoidis vicina). Eleven giant tortoises (C. vandenburghi, C. vicina) received two randomly assigned, oral doses of tramadol (either 1 mg/kg or 5 mg/kg), with a washout period of 3 wk between each dose. The half-life (t½) of orally administered tramadol at 1 mg/kg and 5 mg/kg was 11.9 ± 4.6 h and 13.2 ± 6.1 h, respectively. After oral administration of tramadol at 1 mg/kg and 5 mg/kg, the maximum concentration (Cmax) was 125 ± 69 ng/ml and 518 ± 411 ng/ml, respectively. There were not enough data points to determine pharmacokinetic (PK) parameters for the M1 metabolite from either dose. Tramadol administered orally to giant tortoises at both doses provided measurable plasma concentrations of tramadol for approximately 48 h with occasional transient sedation. Oral tramadol at 5 mg/kg, on average, achieves concentrations of >100 ng/ml, the reported human therapeutic threshold, for 24 h. Based on the low levels of M1 seen in this study, M1 may not be a major metabolite in this taxon.

Ketamine Versus Tramadol As an Adjunct To PCA Morphine for Postoperative Analgesia After Major Upper Abdominal Surgery: a Prospective, Comparative, Randomized Trial

Background and aims

Patient-controlled analgesia (PCA) with morphine is commonly used to provide analgesia following major surgery, but is not sufficient as a monotherapy strategy. This study aimed to compare the adjunctive analgesic effect of ketamine versus tramadol on postoperative analgesia provided via PCA-morphine in patients undergoing major upper abdominal surgeries.

Methods

Forty-two patients undergoing elective major upper abdominal surgery under general anesthesia were allocated to receive either ketamine (load dose of 0.5 mg kg⁻¹ followed by a continuous infusion of 0.12 mg kg⁻¹ h⁻¹ up to 48 postoperative hours; ketamine group, n = 21) or tramadol (load dose of 1 mg kg⁻¹ followed by a continuous infusion of 0.2 mg kg⁻¹ h⁻¹ up to 48 postoperative hours; tramadol group, n = 21) in addition to their standard postoperative analgesia with PCA-morphine. Postoperative data included morphine consumption, visual analog scale (VAS) scores, and side effects during the first 48 postoperative hours after PCA-morphine initiation.

Results

There were no significant differences in patient demographic and intraoperative data between the two groups. Tramadol group had significantly less total morphine consumption during the first 48 postoperative hours (28.905 [16.504] vs 54.524 [20.846] mg [p < 0.001]) and presented significantly lower VAS scores at rest and mobilization (p < 0.05) than the ketamine group. No statistical difference was recorded between the two groups (p > 0.05) regarding postoperative cough, sedation, hallucinations, pruritus, urine retention, and postoperative nausea and vomiting. However, patients in the ketamine group reported dry mouth more frequently than patients in the tramadol group (p = 0.032).

Conclusions

Postoperative administration of tramadol was superior to ketamine due to significantly reduced opioid consumption and better pain scores in patients receiving PCA-morphine after major upper abdominal surgery.

Perioperative Intravenous Ketamine Infusion for the Prevention of Persistent Post-amputation Pain: A Randomized, Controlled Trial

We hypothesized that perioperative ketamine administration would modify acute central sensitization following amputation and hence reduce the incidence and severity of persistent post-amputation pain (both phantom limb and stump pain). In a randomized, controlled trial, 45 patients undergoing above- or below-knee amputation received ketamine 0.5 mg.kg–1 or placebo as a pre-induction bolus followed by an intravenous infusion of ketamine 0.15 mg.kg–1.h–1 or normal saline for 72 hours postoperatively. Both groups received standardized general anaesthesia followed by patient-controlled intravenous morphine. The surface area of allodynia over the stump was mapped at days 3 and 6. Postamputation pain was assessed at days 3 and 6 and at 6 months postoperatively.

We found no significant difference between groups in the surface area of stump allodynia or in morphine consumption. There was an unexplained, but significant, increase in the incidence of stump pain in the ketamine group at day 3. At six-month review, the incidence of phantom pain was 47% in the ketamine group and 71% in the control group. This did not reach statistical significance (P=0.28) as the power of the study was based on the search for a large treatment effect. The incidence of stump pain at six months was 47% in the ketamine group and 35% in the control group (P=0.72). There were no significant between-group differences in pain severity throughout the study period.

Ketamine at the dose administered did not significantly reduce acute central sensitization or the incidence and severity of post-amputation pain.

Parturient on Magnesium Infusion and Its Effectiveness as an Adjuvant Analgesic after Cesarean Delivery: A Retrospective Analysis

Background

Perioperative use of intravenous magnesium as part of multimodal analgesia has been increasing in recent years in an effort to decrease the use of opioids. The aim of this study was to evaluate the effectiveness of magnesium sulfate infusion in lowering analgesic requirement and decreasing the intensity of pain score after cesarean delivery.

Methods

Sixty-four patients who underwent cesarean delivery under spinal anesthesia were included in this medical record review: 32 patients received magnesium infusion after cesarean delivery for treatment of mild preeclampsia (Mg group); 32 patients received routine post-cesarean delivery care (control group). Primary outcome was total analgesic consumption and secondary was visual analogue scores (VAS) of pain in each group during the first 24 hours following delivery. These measures were compared using Student's t-tests and Mann-Whitney U-tests.

Results

Our study found that patients in the Mg group had significantly less requirement for analgesia than the control group. In the 24 h after cesarean delivery, the Mg group received significantly less intravenous ketorolac (the standard initial rescue analgesic agent) when compared to the control group (79 ± 23 mg vs. 90 ± 0 mg; P = 0.008). The Mg group also received significantly less intravenous morphine equivalents than the control group (median 5.0 (IRQ: 0.0 - 10.0) vs. 9.3 (IRQ: 6.0 - 21.1); P = 0.001) during the first 24 h after cesarean delivery. The Mg group also had significantly lower VAS pain scores than the control group (median 1.75 (IRQ: 0.4 - 2.6) vs. median 3.2 (IRQ: 2.3 - 4.5); P < 0.001).

Conclusions

Our results suggest that magnesium sulfate infusion decreases total analgesic requirements and lowers VAS pain scores during the first 24 h after cesarean delivery.

Perioperative intravenous ketamine for acute postoperative pain in adults

BACKGROUND

Inadequate pain management after surgery increases the risk of postoperative complications and may predispose for chronic postsurgical pain. Perioperative ketamine may enhance conventional analgesics in the acute postoperative setting.

OBJECTIVES

To evaluate the efficacy and safety of perioperative intravenous ketamine in adult patients when used for the treatment or prevention of acute pain following general anaesthesia.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to July 2018 and three trials registers (metaRegister of controlled trials, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP)) together with reference checking, citation searching and contact with study authors to identify additional studies.

SELECTION CRITERIA

We sought randomised, double-blind, controlled trials of adults undergoing surgery under general anaesthesia and being treated with perioperative intravenous ketamine. Studies compared ketamine with placebo, or compared ketamine plus a basic analgesic, such as morphine or non-steroidal anti-inflammatory drug (NSAID), with a basic analgesic alone.

DATA COLLECTION AND ANALYSIS

Two review authors searched for studies, extracted efficacy and adverse event data, examined issues of study quality and potential bias, and performed analyses. Primary outcomes were opioid consumption and pain intensity at rest and during movement at 24 and 48 hours postoperatively. Secondary outcomes were time to first analgesic request, assessment of postoperative hyperalgesia, central nervous system (CNS) adverse effects, and postoperative nausea and vomiting. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included 130 studies with 8341 participants. Ketamine was given to 4588 participants and 3753 participants served as controls. Types of surgery included ear, nose or throat surgery, wisdom tooth extraction, thoracotomy, lumbar fusion surgery, microdiscectomy, hip joint replacement surgery, knee joint replacement surgery, anterior cruciate ligament repair, knee arthroscopy, mastectomy, haemorrhoidectomy, abdominal surgery, radical prostatectomy, thyroid surgery, elective caesarean section, and laparoscopic surgery. Racemic ketamine bolus doses were predominantly 0.25 mg to 1 mg, and infusions 2 to 5 µg/kg/minute; 10 studies used only S-ketamine and one only R-ketamine. Risk of bias was generally low or uncertain, except for study size; most had fewer than 50 participants per treatment arm, resulting in high heterogeneity, as expected, for most analyses. We did not stratify the main analysis by type of surgery or any other factor, such as dose or timing of ketamine administration, and used a non-stratified analysis.Perioperative intravenous ketamine reduced postoperative opioid consumption over 24 hours by 8 mg morphine equivalents (95% CI 6 to 9; 19% from 42 mg consumed by participants given placebo, moderate-quality evidence; 65 studies, 4004 participants). Over 48 hours, opioid consumption was 13 mg lower (95% CI 10 to 15; 19% from 67 mg with placebo, moderate-quality evidence; 37 studies, 2449 participants).Perioperative intravenous ketamine reduced pain at rest at 24 hours by 5/100 mm on a visual analogue scale (95% CI 4 to 7; 19% lower from 26/100 mm with placebo, high-quality evidence; 82 studies, 5004 participants), and at 48 hours by 5/100 mm (95% CI 3 to 7; 22% lower from 23/100 mm, high-quality evidence; 49 studies, 2962 participants). Pain during movement was reduced at 24 hours (6/100 mm, 14% lower from 42/100 mm, moderate-quality evidence; 29 studies, 1806 participants), and 48 hours (6/100 mm, 16% lower from 37 mm, low-quality evidence; 23 studies, 1353 participants).Results for primary outcomes were consistent when analysed by pain at rest or on movement, operation type, and timing of administration, or sensitivity to study size and pain intensity. No analysis by dose was possible. There was no difference when nitrous oxide was used. We downgraded the quality of the evidence once if numbers of participants were large but small-study effects were present, or twice if numbers were small and small-study effects likely but testing not possible.Ketamine increased the time for the first postoperative analgesic request by 54 minutes (95% CI 37 to 71 minutes), from a mean of 39 minutes with placebo (moderate-quality evidence; 31 studies, 1678 participants). Ketamine reduced the area of postoperative hyperalgesia by 7 cm² (95% CI -11.9 to -2.2), compared with placebo (very low-quality evidence; 7 studies 333 participants). We downgraded the quality of evidence because of small-study effects or because the number of participants was below 400.CNS adverse events occurred in 52 studies, while 53 studies reported of absence of CNS adverse events. Overall, 187/3614 (5%) participants receiving ketamine and 122/2924 (4%) receiving control treatment experienced an adverse event (RR 1.2, 95% CI 0.95 to 1.4; high-quality evidence; 105 studies, 6538 participants). Ketamine reduced postoperative nausea and vomiting from 27% with placebo to 23% with ketamine (RR 0.88, 95% CI 0.81 to 0.96; the number needed to treat to prevent one episode of postoperative nausea and vomiting with perioperative intravenous ketamine administration was 24 (95% CI 16 to 54; high-quality evidence; 95 studies, 5965 participants).

AUTHORS' CONCLUSIONS

Perioperative intravenous ketamine probably reduces postoperative analgesic consumption and pain intensity. Results were consistent in different operation types or timing of ketamine administration, with larger and smaller studies, and by higher and lower pain intensity. CNS adverse events were little different with ketamine or control. Perioperative intravenous ketamine probably reduces postoperative nausea and vomiting by a small extent, of arguable clinical relevance.

Pain Management in the Emergency Department: a Review Article on Options and Methods

CONTEXT

The aim of this review is to recognizing different methods of analgesia for emergency medicine physicians (EMPs) allows them to have various pain relief methods to reduce pain and to be able to use it according to the patient's condition and to improve the quality of their services.

EVIDENCE ACQUISITION

In this review article, the search engines and scientific databases of Google Scholar, Science Direct, PubMed, Medline, Scopus, and Cochrane for emergency pain management methods were reviewed. Among the findings, high quality articles were eventually selected from 2000 to 2018, and after reviewing them, we have conducted a comprehensive comparison of the usual methods of pain control in the emergency department (ED).

RESULTS

For better understanding, the results are reported in to separate subheadings including "Parenteral agents" and "Regional blocks". Non-opioids analgesics such as nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are commonly used in the treatment of acute pain. However, the relief of acute moderate to severe pain usually requires opioid agents. Considering the side effects of systemic drugs and the restrictions on the use of analgesics, especially opioids, regional blocks of pain as part of a multimodal analgesic strategy can be helpful.

CONCLUSION

This study was designed to investigate and identify the disadvantages and advantages of using each drug to be able to make the right choices in different clinical situations for patients while paying attention to the limitations of the use of these analgesic drugs.

Benefit and harm of adding ketamine to an opioid in a patient-controlled analgesia device for the control of postoperative pain: systematic review and meta-analyses of randomized controlled trials with trial sequential analyses

Ketamine is often added to opioids in patient-controlled analgesia devices. We tested whether in surgical patients, ketamine added to an opioid patient-controlled analgesia decreased pain intensity by ≥25%, cumulative opioid consumption by ≥30%, the risk of postoperative nausea and vomiting by ≥30%, the risk of respiratory adverse effects by ≥50%, and increased the risk of hallucination not more than 2-fold. In addition, we searched for evidence of dose-responsiveness. Nineteen randomized trials (1349 adults, 104 children) testing different ketamine regimens added to various opioids were identified through searches in databases and bibliographies (to 04.2016). In 9 trials (595 patients), pain intensity at rest at 24 hours was decreased by 32% with ketamine (weighted mean difference -1.1 cm on the 0-10 cm visual analog scale [98% CI, -1.8 to -0.39], P < 0.001). In 7 trials (495 patients), cumulative 24 hours morphine consumption was decreased by 28% with ketamine (weighted mean difference -12.9 mg [-22.4 to -3.35], P = 0.002). In 7 trials (435 patients), the incidence of postoperative nausea and vomiting was decreased by 44% with ketamine (risk ratio 0.56 [0.40 to 0.78], P < 0.001). There was no evidence of a difference in the incidence of respiratory adverse events (9 trials, 871 patients; risk ratio 0.31 [0.06 to 1.51], P = 0.08) or hallucination (7 trials, 690 patients; odds ratio 1.16 [0.47 to 2.79], P = 0.70). Trial sequential analyses confirmed the significant benefit of ketamine on pain intensity, cumulative morphine consumption, and postoperative nausea and vomiting and its inability to double the risk of hallucination. The available data did not allow us to make a conclusion on respiratory adverse events or to establish dose-responsiveness.

WITHDRAWN: Drugs for preventing postoperative nausea and vomiting

BACKGROUND

Drugs can prevent postoperative nausea and vomiting, but their relative efficacies and side effects have not been compared within one systematic review.

OBJECTIVES

The objective of this review was to assess the prevention of postoperative nausea and vomiting by drugs and the development of any side effects.

SEARCH METHODS

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2004), MEDLINE (January 1966 to May 2004), EMBASE (January 1985 to May 2004), CINAHL (1982 to May 2004), AMED (1985 to May 2004), SIGLE (to May 2004), ISI WOS (to May 2004), LILAC (to May 2004) and INGENTA bibliographies.

SELECTION CRITERIA

We included randomized controlled trials that compared a drug with placebo or another drug, or compared doses or timing of administration, that reported postoperative nausea or vomiting as an outcome.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted outcome data.

MAIN RESULTS

We included 737 studies involving 103,237 people. Compared to placebo, eight drugs prevented postoperative nausea and vomiting: droperidol, metoclopramide, ondansetron, tropisetron, dolasetron, dexamethasone, cyclizine and granisetron. Publication bias makes evidence for differences among these drugs unreliable. The relative risks (RR) versus placebo varied between 0.60 and 0.80, depending upon the drug and outcome. Evidence for side effects was sparse: droperidol was sedative (RR 1.32) and headache was more common after ondansetron (RR 1.16).

AUTHORS' CONCLUSIONS

Either nausea or vomiting is reported to affect, at most, 80 out of 100 people after surgery. If all 100 of these people are given one of the listed drugs, about 28 would benefit and 72 would not. Nausea and vomiting are usually less common and, therefore, drugs are less useful. For 100 people, of whom 30 would vomit or feel sick after surgery if given placebo, 10 people would benefit from a drug and 90 would not. Between one to five patients out of every 100 people may experience a mild side effect, such as sedation or headache, when given an antiemetic drug. Collaborative research should focus on determining whether antiemetic drugs cause more severe, probably rare, side effects. Further comparison of the antiemetic effect of one drug versus another is not a research priority.

Comparison of the effects of magnesium and ketamine on postoperative pain and morphine consumption. A double-blind randomized controlled clinical study

PURPOSE

To compare the effects of magnesium sulfate and ketamine on postoperative pain and total morphine consumption in a placebo-controlled design.

METHODS

One hundred and twenty women scheduled for total abdominal hysterectomy were included in this prospective, randomized, double-blind study. Postoperatively, when the Numeric Pain Rating Scale (NPRS) was four or more, IV-PCA morphine was applied to all patients. The patients were randomized into three groups: Group K ketamine, Group M magnesium, and Group C saline received as infusion. Total morphine consumption for 48h, pain scores, adverse effects, and patients' satisfaction were evaluated.

RESULTS

Total morphine consumption was significantly lower in Group K (32.6±9.2 mg) than in Group M (58.9±6.5 mg) and in Group C (65.7±8.2 mg). The satisfaction level of patients in Group K was higher than the other two groups (p<0.05). Pruritus and nausea were observed more frequently in Group C. CONCLUSİON: The addition of ketamine to IV-PCA morphine reduces the total consumption of morphine without psychotic effects; however, magnesium did not influence morphine consumption.

Assessment of the Analgesic Effect of Magnesium and Morphine in Combination in Patients With Cancer Pain: A Comparative Randomized Double-Blind Study

Background:

Morphine is the first-choice drug for moderate-to-severe cancer pain, nevertheless, some patients do not achieve adequate pain relief or exhibit intolerable side effects. The purpose of this study was to establish whether the analgesic effect of morphine improves in patients with cancer when administered in combination with magnesium.

Methods:

Randomized double-blind study was conducted with 40 patients older than 18 years with cancer pain using morphine. Group 1 (G1) patients were given magnesium sulfate (65 mg elemental magnesium) twice per day by the oral route. Group 2 (G2) patients were given placebo twice per day. All the patients were administered morphine as needed. They were also given acetaminophen at 2 to 3 g/d. Adjuvants could be used when indicated. The following variables were assessed: pain intensity on a numeric scale at baseline and at weeks 1, 2, 3, and 4; functional performance and quality of life at baseline and week 4; and dose of morphine used.

Results:

No difference was found between the groups as to pain intensity, dose of morphine used, functional performance, quality of life, or side effects. The average daily dose of morphine increased gradually, being significant in G2.

Conclusions:

The use of morphine combined with elemental magnesium at a dose of 65 mg twice per day by patients with cancer did not induce a better analgesic effect, did not improve their functional performance or quality of life, and did not reduce the occurrence of side effects. The dose of morphine increased significantly in G2.

Long-Term Stability of Tramadol and Ketamine Solutions for Patient-Controlled Analgesia Delivery

Background

Subanesthetic doses of ketamine as an adjuvant to tramadol in patient-controlled analgesia (PCA) for postoperative pain have been shown to improve the quality of analgesia. However, there are no such commercially available drug mixtures, and the stability of the combination has rarely been assessed.

Material/Methods

Admixtures were assessed for periods of up to 14 days at 4°C and 25°C. Three different mixtures of tramadol and ketamine (tramadol 5.0 mg/mL + ketamine 0.5 mg/mL, tramadol 5.0 mg/mL + ketamine 1.0 mg/mL, and tramadol 5.0 mg/mL + ketamine 2.0 mg/mL) were prepared in polyolefin bags by combining these 2 drugs with 0.9% sodium chloride (normal saline [NS]). The chemical stability of the admixtures was evaluated by a validated high-performance liquid chromatography (HPLC) method and by measurement of pH values. Solution appearance and color were assessed by observing the samples against black and white backgrounds. Solutions were considered stable if they maintained 90% of the initial concentration of each drug.

Results

The percentages of initial concentration of tramadol and ketamine in the various solutions remained above 98% when stored at 4°C or 25°C over the testing period. No changes in color or turbidity were observed in any of the prepared solutions. Throughout this period, pH values remained stable.

Conclusions

The results indicate that the drug mixtures of tramadol with ketamine in NS for PCA delivery systems were stable for 14 days when stored in polyolefin bags at 4°C or 25°C.

WITHDRAWN: Perioperative ketamine for acute postoperative pain

This review has been amended to include further information on Menigaux 2000 pre pre and Menigaux 2000 post included studies.

At July 2014, this review is out of date and has been withdrawn. This review is correct as of the date of publication. The latest version is available in the ‘Other versions’ tab on The Cochrane Library, and may still be useful to readers.

The editorial group responsible for this previously published document have withdrawn it from publication.

Best practice in the administration of analgesia in postoncological surgery

The rationale for using multimodal analgesia after any major surgery is achievement of adequate analgesia while avoiding the unwanted effects of large doses of any analgesic, in particular opioids. There are two reasons why we can hypothesize that multimodal analgesia might have a significant impact on cancer-related outcomes in the context of oncological orthopedic surgery. First, because multimodal analgesia is a key component of enhanced-recovery pathways and can accelerate return to intended oncological therapy. And second, because some of the analgesic used in multimodal analgesia (i.e., COX inhibitors, local analgesics and dexamethasone) can induce apoptosis in cancer cells and/or diminish the inflammatory response during surgery which itself can facilitate tumor growth.

Butorphanol and ketamine combined in infusion solutions for patient-controlled analgesia administration: a long-term stability study

BACKGROUND

Ketamine in subanesthetic dose added to butorphanol has been reported to give superior pain control when used for intravenous patient-controlled analgesia (PCA) after surgery. However, this admixture is not available commercially and stability data applicable to hospital practice are limited.

MATERIAL/METHODS

The butorphanol-ketamine admixtures were prepared in polyolefin bags and stored in the dark at 4°C, 25°C, or 37°C for 15 days. The initial concentrations were 50-150 microgram/ml for butorphanol and 1-4 mg/ml for ketamine, respectively. The stabilities were determined by visual inspection, pH measurement, and high-pressure liquid chromatography (HPLC) assay of drug concentrations.

RESULTS

Over the 15 days, all solutions were clear in appearance, and no color change or precipitation was observed among the three temperatures. The percentages of initial concentration of each drug were over 95% during the study period, and the pH value did not change significantly.

CONCLUSIONS

The results indicate that the drug mixtures of butorphanol and ketamine in 0.9% sodium chloride injection were stable for 15 days when stored in polyolefin bags at 4°C, 25°C, or 37°C.

Effect of perioperative electroacupuncture as an adjunctive therapy on postoperative analgesia with tramadol and ketamine in prostatectomy: a randomised sham-controlled single-blind trial

OBJECTIVES

To study the analgesic effect of electroacupuncture (EA) as perioperative adjunctive therapy added to a systemic analgesic strategy (including tramadol and ketamine) for postoperative pain, opioid-related side effects and patient satisfaction.

METHODS

In a sham-controlled participant- and observer-blinded trial, 75 patients undergoing radical prostatectomy were randomly assigned to two groups: (1) EA (n=37; tramadol+ketamine+EA) and (2) control (n=38; tramadol+ketamine). EA (100 Hz frequency) was applied at LI4 bilaterally during the closure of the abdominal walls and EA (4 Hz) was applied at ST36 and LI4 bilaterally immediately after extubation. The control group had sham acupuncture without penetration or stimulation. The following outcomes were evaluated: postoperative pain using the Numerical Rating Scale (NRS) and McGill Scale (SF_MPQ), mechanical pain thresholds using algometer application close to the wound, cortisol measurements, rescue analgesia, Spielberger State Trait Anxiety Inventory (STAI Y-6 item), patient satisfaction and opioid side effects.

RESULTS

Pain scores on the NRS and SF_MPQ were significantly lower and electronic pressure algometer measurements were significantly higher in the EA group than in the control group (p<0.001) at all assessments. In the EA group a significant decrease in rescue analgesia was observed at 45 min (p<0.001) and a significant decrease in cortisol levels was also observed (p<0.05). Patients expressed satisfaction with the analgesia, especially in the EA group (p<0.01). Significant delays in the start of bowel movements were observed in the control group at 45 min (p<0.001) and 2 h (p<0.05).

CONCLUSIONS

Adding EA perioperatively should be considered an option as part of a multimodal analgesic strategy.

The effect of intravenous magnesium sulfate infusion on sensory spinal block and postoperative pain score in abdominal hysterectomy

AIM

The aim of this study was to investigate the effect of i.v. infusion of magnesium sulphate during spinal anesthesia on duration of spinal block and postoperative pain.

METHODS

Forty ASA physical status I and status II, aged between 18 and 65, female patients undergoing abdominal hysterectomy under spinal anesthesia were enrolled in this study. Patients in the magnesium group (Group M, n = 20) received magnesium sulphate 65 mg kg(-1) infusion in 250 mL 5% dextrose at 3.5 mL/min rate, and control group (Group C, n = 20) received at the same volume of saline during operation in a double-blind randomized manner. Duration of sensory and motor block, systolic, diastolic, and mean arterial blood pressures, heart rates, pain scores (VAS values), and side effects were recorded for each patient. Blood and CSF samples were taken for analysis of magnesium concentrations.

RESULTS

Regression of sensorial block was longer in Group M when compared with that in Group C (175 ± 39 versus 136 ± 32 min) (P < 0.01). The VAS scores were lower in Group M than those in Group C at the 2 time points postoperatively (P < 0.01).

CONCLUSION

65 mg kg(-1) of magnesium sulphate i.v. infusion under spinal anesthesia prolongs spinal sensorial block duration and decreases pain VAS scores without complication in patients undergoing abdominal hysterectomy.

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

BACKGROUND

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

OBJECTIVES

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Perioperative Systemic Magnesium to Minimize Postoperative Pain

Background:

Systemic magnesium has been used to minimize postoperative pain with conflicting results by clinical studies. It remains unknown whether the administration of perioperative systemic magnesium can minimize postoperative pain. The objective of the current investigation was to evaluate the effect of systemic magnesium on postoperative pain outcomes.

Methods:

A wide search was performed to identify randomized controlled trials that evaluated the effects of systemic magnesium on postoperative pain outcomes in surgical procedures performed under general anesthesia. Meta-analysis was performed using a random-effect model. Publication bias was evaluated by examining the presence of asymmetric funnel plots using Egger regression.

Results:

Twenty randomized clinical trials with 1,257 subjects were included. The weighted mean difference (99% CI) of the combined effects favored magnesium over control for pain at rest (≤4 h, −0.74 [−1.08 to −0.48]; 24 h, −0.36 [−0.63 to −0.09]) and with movement at 24 h, −0.73 (−1.37 to −0.1). Opioid consumption was largely decreased in the systemic magnesium group compared with control, weighted mean difference (99% CI) of −10.52 (−13.50 to −7.54) mg morphine IV equivalents. Publication bias was not present in any of the analysis. Significant heterogeneity was present in some analysis, but it could be partially explained by the sole intraoperative administration of magnesium compared with the intraoperative and postoperative administration. None of the studies reported clinical toxicity related to toxic serum levels of magnesium.

Conclusion:

Systemic administration of perioperative magnesium reduces postoperative pain and opioid consumption. Magnesium administration should be considered as a strategy to mitigate postoperative pain in surgical patients.

Beneficial effects of adding ketamine to intravenous patient-controlled analgesia with fentanyl after the Nuss procedure in pediatric patients

PURPOSE

The aim of this prospective, double-blind, randomized study was to investigate the analgesic effects of low-dose ketamine on intravenous patient-controlled analgesia (IV-PCA) with fentanyl for pain control in pediatric patients following the Nuss procedure for pectus excavatum.

MATERIALS AND METHODS

Sixty pediatric patients undergoing the Nuss procedure were randomly assigned to receive fentanyl (Group F, n=30) or fentanyl plus ketamine (Group FK, n=30). Ten minutes before the end of surgery, following the loading dose of each solution, 0.5 μg/kg/hr of fentanyl or 0.5 μg/kg/hr of fentanyl plus 0.15 mg/kg/hr of ketamine was infused via an IV-PCA pump (basal rate, 1 mL/hr; bolus, 0.5 mL; lock out interval, 30 min). Fentanyl consumption, pain score, ketorolac use, nausea/vomiting, ondansetron use, pruritus, respiratory depression, hallucination, dreaming, and parent satisfaction with pain control were measured throughout the 48 hours following surgery.

RESULTS

The pain scores, ketorolac use, and fentanyl consumption of Group FK were significantly lower than in Group F (p<0.05). The incidence of nausea/vomiting and ondansetron use in Group FK was significantly lower than in Group F (p<0.05). There were no reports of respiratory depression, hallucination or dreaming. Parent satisfaction with pain control was similar between the two groups.

CONCLUSION

We concluded that low-dose ketamine added to IV-PCA with fentanyl after the Nuss procedure in pediatric patients can reduce pain scores, consumption of fentanyl, and incidence of nausea/vomiting without increasing side effects.

Chemical stability of tramadol hydrochloride injection admixed with selected pain drugs

BACKGROUND

Tramadol hydrochloride (HCl) and ketorolac tromethamine are analgesic drugs, which are commonly used in combination in postoperative pain management. According to some studies, metoclopramide and magnesium sulfate (MgSO(4)) as adjuvant agents can improve analgesia and decrease the need for other pain drugs.

MATERIALS AND METHODS

The chemical stability of tramadol HCl combined with ketorolac tromethamine and metoclopramide HCl has been studied using a stability-indicating high-performance liquid chromatographic assay method. Calibration curves were produced using linear regression of the peak area against concentration of each drug, with an r(2) value ≥ 0.96. Our aim was to investigate the stability of admixture solution of tramadol HCl combined with ketorolac tromethamine and metoclopramide HCl for 48 h (25°C) and 5 days (5°C), with MgSO(4), which has never been assessed.

RESULTS

Data obtained for admixtures prepared and stored at temperatures of 25°C and 5°C, show that all drugs have reached at least 98% of the initial concentration.

CONCLUSIONS

For the purpose of pre-preparing drug admixtures to use with confidence, tramadol HCl infusions may be prepared in advance and then thawed before use in clinical units. On the basis of our results, the intravenous mixture of tramadol (7.69 mg/mL), metoclopramide (0.19 mg/mL), ketorolac (1.15 mg/mL), and magnesium sulfate (77 mg/mL) may be considered for a possible commercial formulation.

The effect of intraarticular combinations of tramadol and ropivacaine with ketamine on postoperative pain after arthroscopic meniscectomy

INTRODUCTION

The purpose of this prospective randomized study was to evaluate the effects of intraarticular combinations of tramadol and ropivacaine with ketamine in postoperative pain control of patients undergoing arthroscopic meniscectomy.

MATERIALS AND METHODS

We randomly divided 80 patients into four groups to receive intraarticular 50 mg tramadol (Group T), 50 mg tramadol with 0.5 mg kg(-1) ketamine (Group TK), 75 mg ropivacaine (Group R), 75 mg ropivacaine with 0.5 mg kg(-1) ketamine (Group RK) in 20 ml normal saline at the end of surgery. Postoperative analgesia was provided with patient-controlled analgesia with morphine. Postoperative pain scores, total morphine consumption amount and side effects were recorded at intervals of 0, 1, 2, 4, 8, 12 and 24 h after the operation.

RESULTS

Pain scores were higher in Group T when compared with Group R and Group RK at second and fourth hours, also compared with Group RK at zeroth, first, second, fourth and eighth hours. Total morphine consumption amount was found to be higher in Group T when compared to Group TK at eighth and twelfth hours and Group RK at eighth hours (P < 0.05). Total morphine consumption was lowest in Group TK (P < 0.05). There were no significant differences among the study groups regarding side effects.

CONCLUSIONS

Administration of intraarticular tramadol-ketamine combination was found to be more effective in decreasing postoperative daily analgesic consumption.

Effects of perioperative intravenous low dose of ketamine on postoperative analgesia in children

BACKGROUND AND OBJECTIVE

Low dose of ketamine reduces postoperative pain and opioid consumption in adult studies. However, there are only a few data with controversial results in the paediatric population. The aim of this randomized controlled trial was to evaluate the use of low doses of intravenous ketamine on postoperative pain in children after surgery on the lower part of the body.

METHODS

Thirty-seven children with ASA 1 or 2 from 6 to 60 months of age, undergoing scheduled surgery, were prospectively enrolled in a double blind sequential trial using a triangular test, with analysis every 10 patients treated. The children were randomly assigned to intravenously receive saline or 0.15 mg kg(-1) ketamine before surgery, followed by a continuous infusion of 1.4 microg kg(-1) min(-1) over 24 h. After sevoflurane induction and tracheal intubation, a caudal anaesthesia was performed in all children (1 ml kg(-1) of bupivacaine 0.25% with epinephrine). The postoperative analgesic technique was standardized with intravenous paracetamol 15 mg kg(-1) 6 h(-1), rectal morniflumate (20 mg kg(-1) 12 h(-1)) and intravenous nalbuphine infusion 1.2 mg kg(-1) 24 h(-1) for 24 h. The Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) scores, additional bolus of nalbuphine (if CHEOPS >7) and side effects were recorded from eye opening every 2 h over 24 h. The primary endpoint was the CHEOPS area under the curve.

RESULTS

There was no difference in terms of additional bolus of nalbuphine as well as CHEOPS score area under the curve between groups, that is, 76 +/- 10 in the ketamine group versus 74 +/- 7 in the control group. No psychomimetic side effects were noted.

CONCLUSION

The study failed to show any evidence of benefit of ketamine to improve analgesia in children when given in addition to a multimodal analgesic therapy with paracetamol, a NSAID and an opiate.

Intravenous magnesium sulfate for post-operative pain in patients undergoing lower limb orthopedic surgery

INTRODUCTION

This study looks at the effect of supplementary intravenous magnesium sulfate on acute pain when administered in patients undergoing lower limb orthopedic surgery using spinal anesthesia with bupivacaine.

METHOD AND MATERIALS

In this double-blind, randomized, placebo-controlled clinical trial, 60 patients were selected and randomly divided into two groups. Efforts were made to place both groups under the same method of anesthesia. One group received 8 mg/kg intravenous magnesium sulfate, started before the incision and continued up to the end of the surgical procedure, using a 50 ml syringe, via a peripheral large bore catheter; the second group received the same volume of placebos using the same method. To present the results, mean (+/- SD) was used; a P value of <0.05 was considered significant.

RESULTS

There was no difference between the two groups in terms of the basic variables. Pain reported by the first group that received magnesium sulfate was significantly less at the first, third, sixth and 12th hours after the operation in comparison with the group that received placebo. Also, the intravenous morphine requirements in the first 24 h after the surgery were less in the magnesium group (4.2 +/- 1.6 mg) than in the control group (9.8 +/- 2.1 mg).

CONCLUSION

Intravenous magnesium sulfate can serve as a supplementary analgesic therapy to suppress the acute post-operative pain, leading to less morphine requirements in the first 24 h.

Effect of magnesium sulfate on extubation time and acute pain in coronary artery bypass surgery

BACKGROUND

Post-operative pain control is one of the greatest concerns for both physicians and patients. In this study, the effect of magnesium sulfate (MgSO(4)) solution infusion on post-operative pain scores and extubation time in patients undergoing elective coronary artery bypass graft (CABG) surgeries was assessed.

METHODS

In a double-blind, randomized, placebo-controlled clinical trial, 218 patients scheduled for elective CABG were selected and randomly assigned to two groups. After matching inclusion and exclusion criteria for the patients, intravenous MgSO(4) was administered intraoperatively for one group and placebo to the second group. Except for this, all the cases were similar regarding anesthesia and surgery.

RESULTS

The MgSO(4) patients were extubated sooner compared with the placebo group. Pain scores reported by the group who received MgSO(4) were less at the 6th, 12th, 18th and 24th hours after the operation; also, they needed less morphine sulfate during this period.

CONCLUSION

The results demonstrated a significantly shortened post-operative time for extubation and reduced acute post-operative pain scores by intravenous MgSO(4) infusion during elective CABG surgery.

No morphine sparing effect of ketamine added to morphine for patient-controlled intravenous analgesia after uterine artery embolization

BACKGROUND

Pain following embolization of the uterine arteries (UAEs) is variable and may be very severe requiring large doses of parenteral opioids for relief. The present study tested the hypothesis that the addition of ketamine to i.v. patient-controlled morphine reduces the amount of morphine required for pain-control during the first 24 h after UAE embolization.

METHODS

Fifty-six patients undergoing UAE embolization for treatment of symptomatic uterine leiomyomata were randomized to receive either 2 mg/ml of morphine (Control group, n=30) or 2 mg/ml of both morphine and ketamine (Ketamine group, n=26) by i.v. patient-controlled analgesia (IV-PCA). Pump settings were bolus dose 1 ml, lockout 10 min, no background infusion. In addition, all patients received diclofenac and acetaminophen for pain relief. Pain scores, morphine consumption and adverse events like nausea, vomiting, itching, visual disturbances, anxiety, dreaming and hallucinations, if any, were recorded for 24 h after embolization.

RESULTS

The mean +/- SD 24-h consumption of patient-controlled morphine was 38.3 +/- 21.0 mg in the Ketamine group vs. 33.3 +/- 18.3 mg in the Control group (NS). The difference between the means was 5.0 mg (95% confidence interval: -5.7; 15.6). One patient in the Ketamine group vs. none in the Control group experienced auditory hallucinations.

CONCLUSION

Studying an unselected group of patients undergoing embolization of the UAEs for treatment of symptomatic uterine leiomyomata under conditions of basal analgesia with acetaminophen and diclofenac, we failed to demonstrate any morphine-sparing effect of IV-PCA ketamine and morphine compared with IV-PCA morphine alone.

Thiopental and halothane dose-sparing effects of magnesium sulphate in dogs

OBJECTIVE

To evaluate the effect of pre- and intraoperatively administered magnesium sulphate (MgSO(4)) on the induction dose of thiopental and of halothane for maintenance of anaesthesia in dogs undergoing ovariohysterectomy (OHE).

STUDY DESIGN

Prospective, double-blind, randomized, placebo-controlled study.

ANIMALS

Forty-six healthy, ASA physical status 1 dogs, scheduled for elective OHE.

METHODS

The dogs were randomly assigned to receive a bolus of 50 mg kg(-1) MgSO(4) intravenously (IV), just before induction of anaesthesia, followed by a constant rate infusion (CRI) of 12 mg kg(-1) hour(-1) MgSO(4) intraoperatively (group Mg, n = 27) or a placebo bolus and CRI of 0.9% sodium chloride (NaCl) (group C, n = 19), approximately 30 minutes after premedication with acepromazine (0.05 mg kg(-1), intramuscularly, IM) and carprofen (4 mg kg(-1), subcutaneously, SC). Anaesthesia was induced with thiopental administered to effect and maintained with halothane in oxygen. End-tidal halothane (ET(hal)) was adjusted to achieve adequate depth of anaesthesia. Blood samples were obtained pre- and postoperatively for measurement of total serum magnesium concentration.

RESULTS

The mean dose of thiopental was statistically lower (p < 0.0005) and the mean standardized ET(hal) concentration and end-tidal carbon dioxide partial pressure (Pe'CO(2)) areas under the curve were statistically smaller (p < 0.0005 and 0.014 respectively) in group Mg. Postoperatively the mean total serum magnesium concentration was statistically higher than the preoperative value (p < 0.0005) in group Mg, but not in group C. Nausea, associated with the MgSO(4) bolus injection, was observed in six dogs in group Mg, two of which vomited prior to induction of anaesthesia.

CONCLUSIONS AND CLINICAL RELEVANCE

Magnesium sulphate administration reduced the induction dose of thiopental and ET(hal) concentration for maintenance of anaesthesia in dogs undergoing OHE. Observed side effects were nausea and vomiting.

Magnesium as an adjuvant to postoperative analgesia: a systematic review of randomized trials

BACKGROUND

Randomized trials have reached different conclusions as to whether magnesium is a useful adjuvant to postoperative analgesia.

METHODS

We performed a comprehensive search (electronic databases, bibliographies, all languages, to 4.2006) for randomized comparisons of magnesium and placebo in the surgical setting. Information on postoperative pain intensity and analgesic requirements was extracted from the trials and compared qualitatively. Dichotomous data on adverse effects were combined using classic methods of meta-analysis.

RESULTS

Fourteen randomized trials (778 patients, 404 received magnesium) tested magnesium laevulinate, gluconate or sulfate. With magnesium, postoperative pain intensity was significantly decreased in four (29%) trials, was no different from placebo in seven (50%), and was increased in one (7%); two trials (14%) did not report on pain intensity. With magnesium, postoperative analgesic requirements were significantly reduced in eight (57%) trials, were no different from placebo in five (36%), and were increased in one (7%). Magnesium-treated patients had less postoperative shivering (relative risk 0.38, 95% confidence interval 0.17-0.88, number-needed-to-treat 14). Seven trials reported on magnesium serum levels. In all, serum levels were increased in patients who received magnesium; in six, serum levels were decreased in those who received placebo.

CONCLUSIONS

These trials do not provide convincing evidence that perioperative magnesium may have favorable effects on postoperative pain intensity and analgesic requirements. Perioperative magnesium supplementation prevents postoperative hypomagnesemia and decreases the incidence of postoperative shivering. It may be worthwhile to further study the role of magnesium as a supplement to postoperative analgesia, since this relatively harmless molecule is inexpensive, and the biological basis for its potential antinociceptive effect is promising.

The Addition of a Small-Dose Ketamine Infusion to Tramadol for Postoperative Analgesia: A Double-Blinded, Placebo-Controlled, Randomized Trial After Abdominal Surgery

BACKGROUND

There are few data on combining ketamine with tramadol for postoperative analgesia in humans. We tested the hypothesis that adding ketamine to tramadol would improve analgesia after major abdominal surgery.

METHOD

In this double-blind, randomized, controlled trial, adult patients (n = 120) having elective laparotomy were randomly assigned to a ketamine group (intraoperative ketamine 0.3 mg/kg and postoperative infusion at 0.1 mg x kg(-1) x h(-1) or control group (equivalent volume/rate of normal saline). All patients received intraoperative tramadol 3 mg/kg and a tramadol infusion (0.2 mg x kg(-1) x h(-1) for 48 h postoperatively and had morphine patient-controlled analgesia available for rescue analgesia.

RESULTS

The ketamine group had less pain at rest (P = 0.01) and with movement (P = 0.02) and required less morphine (P = 0.003) throughout the 48-h study period. In the 0-24 h period, ketamine improved subjective analgesic efficacy (P = 0.008), was less sedating (P = 0.03), and required fewer physician interventions to manage severe pain (P = 0.01). Hallucinations were more common in ketamine patients, but other side effects were similar.

CONCLUSION

Small-dose ketamine was a useful addition to tramadol and morphine after major abdominal surgery.

Patient-controlled analgesia in the management of postoperative pain

Patient-controlled analgesia (PCA) is a delivery system with which patients self-administer predetermined doses of analgesic medication to relieve their pain. Since its introduction in the early 1980s, the daily management of postoperative pain has been extensively optimised. The use of PCA in hospitals has been increasing because of its proven advantages over conventional intramuscular injections. These include improved pain relief, greater patient satisfaction, less sedation and fewer postoperative complications. All PCA modes contain the following variables: initial loading dose, demand dose, lockout interval, background infusion rate and 1-hour or 4-hour limits. Morphine is the most studied and most commonly used intravenous drug for PCA. In spite of the fact that it is the 'first choice' for PCA, other opioids have been successfully used for this option. The most observed adverse effects of opioid-based PCA are nausea and vomiting, pruritus, respiratory depression, sedation, confusion and urinary retention. Although intravenous PCA is the most studied route of PCA, alternative routes have extensively been described in the literature. PCA by means of peridural catheters and peripheral nerve catheters are the most studied. Recently, transdermal PCA has been described. The use of peripheral or neuraxial nerve blocks is recommended to avoid the so called opioid tolerance observed with the intravenous administration of opioids. Numerous studies have shown the superiority of epidural PCA to intravenous PCA. The beneficial postoperative effects of epidural analgesia are more apparent for high-risk patients or those undergoing higher risk procedures. PCA with peripheral nerve catheters results in increased postoperative analgesia and satisfaction for surgery on upper and lower extremities. Serious complications occur rarely with these catheters. With the introduction of an Acute Pain Service, management of postoperative pain can be improved. This will also help to minimise adverse effects related to PCA and to avoid lethal mishaps.

Drugs for preventing postoperative nausea and vomiting

BACKGROUND

Drugs can prevent postoperative nausea and vomiting, but their relative efficacies and side effects have not been compared within one systematic review.

OBJECTIVES

The objective of this review was to assess the prevention of postoperative nausea and vomiting by drugs and the development of any side effects.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2004), MEDLINE (January 1966 to May 2004), EMBASE (January 1985 to May 2004), CINAHL (1982 to May 2004), AMED (1985 to May 2004), SIGLE (to May 2004), ISI WOS (to May 2004), LILAC (to May 2004) and INGENTA bibliographies.

SELECTION CRITERIA

We included randomized controlled trials that compared a drug with placebo or another drug, or compared doses or timing of administration, that reported postoperative nausea or vomiting as an outcome.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted outcome data.

MAIN RESULTS

We included 737 studies involving 103,237 people. Compared to placebo, eight drugs prevented postoperative nausea and vomiting: droperidol, metoclopramide, ondansetron, tropisetron, dolasetron, dexamethasone, cyclizine and granisetron. Publication bias makes evidence for differences among these drugs unreliable. The relative risks (RR) versus placebo varied between 0.60 and 0.80, depending upon the drug and outcome. Evidence for side effects was sparse: droperidol was sedative (RR 1.32) and headache was more common after ondansetron (RR 1.16).

AUTHORS' CONCLUSIONS

Either nausea or vomiting is reported to affect, at most, 80 out of 100 people after surgery. If all 100 of these people are given one of the listed drugs, about 28 would benefit and 72 would not. Nausea and vomiting are usually less common and, therefore, drugs are less useful. For 100 people, of whom 30 would vomit or feel sick after surgery if given placebo, 10 people would benefit from a drug and 90 would not. Between one to five patients out of every 100 people may experience a mild side effect, such as sedation or headache, when given an antiemetic drug. Collaborative research should focus on determining whether antiemetic drugs cause more severe, probably rare, side effects. Further comparison of the antiemetic effect of one drug versus another is not a research priority.

Does magnesium sulfate reduce the short- and long-term requirements for pain relief after caesarean delivery? A double-blind placebo-controlled trial

OBJECTIVE

The purpose of this study was to determine whether magnesium sulfate decreases postoperative pain and analgesic consumption.

STUDY DESIGN

Women who underwent elective cesarean delivery were randomized into groups according to high-dose magnesium sulfate (50 mg/kg load and 2 g/h), low-dose magnesium sulfate (25 mg/kg load and 1 g/h), or placebo. Before the delivery, the dose of patient-controlled opioid that was used and the visual analogs of pain during the first 48 hours after delivery and at 6 weeks were assessed.

RESULTS

Forty-two women were assigned randomly to the high-dose arm; 38 women were assigned to the low-dose magnesium arms, and 40 women were assigned to the control arm. The cumulative opioid use (P = .636); pain scores at 6, 12, 24, and 48 hours at rest (P = .786) and with movement (P = .179); the use of analgesics after hospital discharge (P = .711); and wound pain with movement (P = .429) or pressure (P = .144) after 6 weeks were similar.

CONCLUSION

Magnesium sulfate does not reduce the severity of short-term or long-term (6 weeks) pain after cesarean delivery.

Magnesium moderately decreases remifentanil dosage required for pain management after cardiac surgery †

BACKGROUND

Magnesium is a calcium and an NMDA-receptor antagonist and can modify important mechanisms of nociception. We evaluated the co-analgesic effect of magnesium in the postoperative setting after on-pump cardiac surgery.

METHODS

Forty patients randomly received either magnesium gluconate as an i.v. bolus of 0.21 mmol kg(-1) (86.5 mg kg(-1)) followed by a continuous infusion of 0.03 mmol(-1) kg(-1) h(-1) (13.8 mg kg(-1) h(-1)) or placebo for 12 h after tracheal extubation. After surgery, remifentanil was decreased to 0.05 microg kg(-1) min(-1) and titrated according to a pain intensity score (PIS, range 1-6) in the intubated, awake patient and a VAS scale (range 1-100) after extubation. If PIS was > or =3 or VAS > or =30, the infusion was increased by 0.01 microg kg(-1) min(-1); if ventilatory frequency was < or =10 min(-1) it was decreased by the same magnitude.

RESULTS

Magnesium lowered the cumulative remifentanil requirement after surgery (P<0.05). PIS > or =3 was more frequent in the placebo group (P<0.05). Despite increased remifentanil demand, VAS scores were also higher in the placebo group at 8 (2 vs 8) and 9 h after extubation (2 vs 7) (P<0.05). Dose reductions attributable to a ventilatory frequency < or =10 min(-1) occurred more often in the magnesium group (17 vs 6; P<0.05). However, time to tracheal extubation was not prolonged.

CONCLUSIONS

Magnesium gluconate moderately reduced the remifentanil consumption without serious side-effects. The opioid-sparing effect of magnesium may be greater at higher pain intensities and with increased dosages.

Perioperative ketamine for acute postoperative pain

BACKGROUND

Postoperative pain management is often limited by adverse effects such as nausea and vomiting. Adjuvant treatment with an inexpensive opioid-sparing drug such as ketamine may be of value in giving better analgesia with fewer adverse effects.

OBJECTIVES

To evaluate the effectiveness and tolerability of ketamine administered perioperatively in the treatment of acute postoperative pain in adults.

SEARCH STRATEGY

Studies were identified from MEDLINE (1966-2004), EMBASE (1980-2004), the Cochrane Library (2004) and by handsearching reference lists from review articles and trials. The manufacturer of ketamine (Pfizer) provided search results from their in-house database, PARDLARS.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of adult patients undergoing surgery, being treated with perioperative ketamine or placebo. Studies where ketamine was administered in addition to a basic analgesic (such as morphine or NSAID) in one study group, and compared with a group receiving the same basic analgesic (but without ketamine) in another group, were also included.

DATA COLLECTION AND ANALYSIS

Two independent reviewers identified fifty five RCTs for potential inclusion. Quality and validity assessment was performed by two independent reviewers. In the case of discrepancy, a third reviewer was consulted. Patient reported pain intensity and pain relief was assessed using visual analogue scales or verbal rating scales and adverse effects data were collated.

MAIN RESULTS

Thirty-seven trials were included (2240 participants). Eighteen trials were excluded.Twenty-seven of the 37 trials found that perioperative subanaesthetic doses of ketamine reduced rescue analgesic requirements or pain intensity, or both. Quantitative analysis showed that treatment with ketamine reduced 24 hour PCA morphine consumption and postoperative nausea or vomiting (PONV). Adverse effects were mild or absent.

AUTHORS' CONCLUSIONS

Ketamine in subanaesthetic dose (that is a dose which is below that required to produce anaesthesia) is effective in reducing morphine requirements in the first 24 hours after surgery. Ketamine also reduces postoperative nausea and vomiting. Adverse effects are mild or absent.

Patient-controlled analgesia

One of the most common methods for providing postoperative analgesia is via patient-controlled analgesia (PCA). Although the typical approach is to administer opioids via a programmable infusion pump, other drugs and other modes of administration are available. This article reviews the history and practice of many aspects of PCA and provides extensive guidelines for the practice of PCA-administered opioids. In addition, potential adverse effects and recommendations for their monitoring and treatment are reviewed.

The effects of magnesium sulphate on sevoflurane minimum alveolar concentrations and haemodynamic responses

BACKGROUND AND OBJECTIVE

Magnesium administered before anaesthesia induction results in a significant reduction in intravenous anaesthetic consumption. The purpose of this study was to evaluate whether the dose of intravenous magnesium sulphate reduces the minimum alveolar anaesthetic concentration of sevoflurane for endotracheal intubation (MACEI) and skin incision (MAC), and attenuates haemodynamic responses.

METHODS

We studied 60 patients who were scheduled for elective surgery. Patients were not premedicated before induction of anaesthesia and were randomly assigned to receive intravenous saline 0.9% (Group I, n = 20) or magnesium sulphate 30 mg kg(-1) bolus + 10 mg kg(-1) h(-1) continuous infusion (Group II, n = 20) or 50 mg kg(-1) bolus + 10 mg kg(-1) h(-1) continuous infusion (Group III, n = 20).

RESULTS

Median and 95% confidence limits for sevoflurane MACEI were 2.68 (2.48-2.85), 2.88 (2.70-3.06) and 2.96 (2.70-3.16), and for sevoflurane MAC were 2.08 (1.76-2.40), 2.26 (2.08-2.47) and 2.40 (2.19-2.68) in Groups I, II and III, respectively. The differences in MACEI and MAC among groups were not statistically significant, except Group III in MAC study (P < 0.05). Mean arterial pressures and heart rate did not increase in Groups II and III after endotracheal intubation and skin incision.

CONCLUSIONS

Magnesium sulphate administered before induction of anaesthesia increases MAC of sevoflurane and reduces cardiovascular responses to intubation.

Analgesic effects of morphine and loperamide in the rat formalin test: interactions with NMDA receptor antagonists

To reveal peripheral components of opiate analgesia, effects of loperamide, opioid agonist which does not penetrate the blood-brain barrier, were examined in formalin and acute thermal pain tests in comparison with morphine. Formalin administration induces pain behaviour such licking/biting of injected paw expressed as two phases. The first phase is caused by C-fibre activation due to peripheral stimulation, the second phase attributed to ongoing input from peripheral site, leading to spinal hyperexcitability, which is dependent on N-methyl-D-aspartate (NMDA) receptor activation. Loperamide (3-10 mg/kg) and morphine (6 mg/kg) reduced formalin-induced nociceptive behaviours and these effects were reversed by naloxone methiodide (0.03-10 mg/kg), opioid receptor antagonist which poorly penetrates the blood-brain barrier. Loperamide action was enhanced only by centrally active NMDA receptor antagonists memantine (3 mg/kg) and CGP 37849 (3 mg/kg), but not by NMDA/glycineB receptor antagonists showing weak or no central nervous system (CNS) activity. Present results suggest that central NMDA receptor blockade may be necessary to enhance analgesia induced through peripheral opioid mechanisms in formalin-evoked nociception.

Peri-operative ketamine for acute post-operative pain: a quantitative and qualitative systematic review (Cochrane review)

BACKGROUND

Post-operative pain management is usually limited by adverse effects such as nausea and vomiting. Adjuvant treatment with an inexpensive opioid-sparing drug such as ketamine may be of value in giving better analgesia with fewer adverse effects. The objective of this systematic review was to evaluate the effectiveness and tolerability of ketamine administered peri-operatively in the treatment of acute post-operative pain in adults.

METHODS

Studies were identified from MEDLINE (1966-2004), EMBASE (1980-2004), the Cochrane Library (2004) and by hand searching reference lists from review articles and trials. The manufacturer of ketamine (Pfizer AS, Lysaker, Norway) provided search results from their in-house database, PARDLARS. Randomized and controlled trials (RCTs) of adult patients undergoing surgery, being treated with peri-operative ketamine, placebo or an active control were considered for inclusion.

RESULTS

Eighteen trials were excluded. Thirty-seven trials were included. Twenty-seven out of 37 trials found that peri-operative ketamine reduced rescue analgesic requirements or pain intensity, or both. Quantitative analysis showed that treatment with ketamine reduced 24-h patient-controlled analgesia (PCA) morphine consumption and post-operative nausea and vomiting (PONV). Adverse effects were mild or absent.

CONCLUSION

In the first 24 h after surgery, ketamine reduces morphine requirements. Ketamine also reduces PONV. Adverse effects are mild or absent. These data should be interpreted with caution as the retrieved studies were heterogenous and the result of the meta-analysis can not be translated into any specific administration regimen with ketamine.

Synergic Antinociceptive Interaction between Tramadol and Gabapentin after Local, Spinal and Systemic Administration

The possible interaction between tramadol and gabapentin on formalin-induced nociception in the rat was assessed. Tramadol, gabapentin or a fixed-dose ratio combination of gabapentin and tramadol were administered peripherally, spinally and orally to rats, and the antinociceptive effect was determined in the 1% formalin test. Isobolographic analyses were used to define the nature of the interactions between drugs. Tramadol, gabapentin and tramadol-gabapentin combinations produced a dose-dependent antinociceptive effect when administered locally, spinally or orally. ED30 values were estimated for the individual drugs and isobolograms were constructed. Theoretical ED30 values for the combination estimated from the isobolograms were 126.8 +/- 11.1 microg/paw, 23.1 +/- 2.6 microg/rat, and 2.23 +/- 0.32 mg/kg for the local, intrathecal and oral routes, respectively. These values were significantly higher than the actually observed ED30 values which were 13.3 +/- 2.1 microg/paw, 8.1 +/- 0.6 microg/rat and 0.71 +/- 0.10 mg/kg, indicating a synergistic interaction. Although efficacy was not improved, local peripheral administration resulted in the highest increase in potency, being about tenfold. Spinal and systemic administration increased potency threefold. Data indicate that low doses of the tramadol-gabapentin combination can interact synergistically to reverse formalin-induced nociception and may represent a therapeutic advantage for clinical treatment of inflammatory pain.

Recent developments in patient-controlled analgesia

Patient-controlled analgesia (PCA) has become the gold standard for acute pain management since it was first introduced 20 years ago, and its merits have been discussed in quite a large number of publications. This review summarizes the more recent developments, such as new application devices and strategies, including intranasal, spinal, and regional PCA; patient-controlled sedation; experience with children and elderly people; and some data from chronic pain situations. Analyzing PCA literature from 2001 onwards confirms the author's long belief that the PCA principle ("WYNIWYG": what you need is what you get) was the most important aspect of a patient-controlled strategy, more or less independent of the type of drug or machine. Discovering this principle has changed the understanding of pain and suffering.

Hypomagnesemia after Major Abdominal Operations in Cancer Patients: Clinical Implications

BACKGROUND

Serum magnesium levels are rarely measured in routine chemistry panels. The extent and impact of postoperative serum magnesium changes remain unclear.

METHODS

One hundred seventy-one cancer patients who had undergone celiotomy procedures during a 38-month period were evaluated retrospectively for postoperative electrolyte alterations, with special emphasis on serum magnesium. Clinicopathologic predictors and early postoperative outcome correlations were examined.

RESULTS

There were 151 major procedures and 20 minor operations. All postoperative electrolyte and hematocrit values were significantly different from preoperative values, except for serum phosphate. Preoperative total serum magnesium (normal range: 1.7-2.5 mg/dL {0.7-1.03 mmol/L}), obtained prior to any bowel cleansing, differed from postoperative levels (means +/- standard deviation: 2.0 +/- 0.46 vs. 1.53 +/- 0.33 mg/dL; p < 0.0001). A lowered postoperative serum magnesium was observed in those patients who had either undergone an operation with curative intent (p = 0.0035), a major resection (vs. no resection, p = 0.0259), or preoperative bowel cleansing with sodium phosphate (p = 0.024). Other laboratory serum parameters that correlated with the postoperative magnesium level included postoperative levels of phosphate (p = 0.009), potassium (p = 0.01), and total calcium (p = 0.012), as well as preoperative calcium (p = 0.017). The complication rate was 20%, with five postoperative deaths (2.9%). Postoperative morbidity was predicted by preoperative potassium (p = 0.004) and albumin levels (p = 0.016); deaths were predicted by postoperative infections (p = 0.0007) and correlated to postoperative hypokalemia (p = 0.03).

CONCLUSIONS

Major abdominal cancer operations lead to significant electrolyte alterations. The severity of these changes correlates with the resection extent, especially in procedures with curative intent. In addition, bowel cleansing with sodium phosphate may participate in lowering serum magnesium as well as other electrolytes. In light of our postoperative magnesium replacement policy, no untoward events could be linked to postoperative hypomagnesemia in this series. To evaluate the impact of postoperative hypomagnesemia or magnesium replacement on postoperative outcomes requires a prospective randomized trial.

Ketamine and postoperative pain – a quantitative systematic review of randomised trials

Ketamine, an N-methyl-D-aspartate receptor antagonist, is known to be analgesic and to induce psychomimetic effects. Benefits and risks of ketamine for the control of postoperative pain are not well understood. We systematically searched for randomised comparisons of ketamine with inactive controls in surgical patients, reporting on pain outcomes, opioid sparing, and adverse effects. Data were combined using a fixed effect model. Fifty-three trials (2839 patients) from 25 countries reported on a large variety of different ketamine regimens and surgical settings. Sixteen studies tested prophylactic intravenous ketamine (median dose 0.4 mg/kg, range (0.1-1.6)) in 850 adults. Weighted mean difference (WMD) for postoperative pain intensity (0-10 cm visual analogue scale) was -0.89 cm at 6 h, -0.42 at 12 h, -0.35 at 24 h and -0.27 at 48 h. Cumulative morphine consumption at 24 h was significantly decreased with ketamine (WMD -15.7 mg). There was no difference in morphine-related adverse effects. The other 37 trials tested in adults or children, prophylactic or therapeutic ketamine orally, intramuscularly, subcutaneously, intra-articulary, caudally, epidurally, transdermally, peripherally or added to a PCA device; meta-analyses were deemed inappropriate. The highest risk of hallucinations was in awake or sedated patients receiving ketamine without benzodiazepine; compared with controls, the odds ratio (OR) was 2.32 (95%CI, 1.09-4.92), number-needed-to-harm (NNH) 21. In patients undergoing general anaesthesia, the incidence of hallucinations was low and independent of benzodiazepine premedication; OR 1.49 (95%CI 0.18-12.6), NNH 286. Despite many published randomised trials, the role of ketamine, as a component of perioperative analgesia, remains unclear.