The value of "multimodal" or "balanced analgesia" in postoperative pain treatment

The cyclooxygenase-2-specific inhibitor parecoxib sodium is as effective as 12 mg of morphine administered intramuscularly for treating pain after gynecologic laparotomy surgery

Parecoxib sodium, the injectable prodrug of valdecoxib, is a cyclooxygenase-2-specific inhibitor that is effective in the treatment of postoperative pain. In this randomized, double-blind, placebo-controlled study, we compared the efficacy of a single dose of parecoxib sodium 40 mg IM with single doses of morphine 6 and 12 mg IM in treating postoperative pain after gynecologic surgery requiring a laparotomy incision. By nearly all efficacy measures (including total pain relief and patient's global evaluation of study medication), parecoxib sodium 40 mg IM demonstrated pain relief and a decrease in pain intensity that was statistically similar to that with morphine 12 mg IM and superior to that with morphine 6 mg IM. Parecoxib sodium 40 mg IM-treated patients also demonstrated a longer time to use of rescue medication than patients treated with both morphine doses, and this dose provided sustained pain relief over the 12-h study period. The incidence of adverse events in the active treatment groups was similar to that observed with placebo. Parecoxib sodium, 40 mg IM, has been shown to be as effective as clinically relevant doses of morphine in patients after gynecologic laparotomy surgery.

Nefopam and ketamine comparably enhance postoperative analgesia

Opioids alone sometimes provide insufficient postoperative analgesia. Coadministration of drugs may reduce opioid use and improve opioid efficacy. We therefore tested the hypothesis that the administration of ketamine or nefopam to postoperative patients with pain only partly alleviated by morphine reduces the amount of subsequent opioid necessary to produce adequate analgesia. Patients (n=77) recovering from major surgery were given up to 9 mg of IV morphine. Those who still had pain were randomly assigned to blinded administration of 1) isotonic saline (control group; n=21), 2) ketamine 10 mg (ketamine group; n=22), or 3) nefopam 20 mg (nefopam group; n=22). Three-milligram morphine boluses were subsequently given at 5-min intervals until adequate analgesia was obtained, until 60 min elapsed after the beginning of study drug administration, or until ventilation became insufficient (respiratory rate <10 breaths/min or saturation by pulse oximetry <95%). Supplemental morphine (i.e., after test drug administration) requirements were significantly more in the control group (mean +/- sd; 17 +/- 10 mg) than in the nefopam (10 +/- 5 mg; P <0.005) or ketamine (9 +/- 5 mg; P <0.001) groups. Morphine titration was successful in all ketamine and nefopam patients but failed in four control patients (two because of respiratory toxicity and two because of persistent pain). Tachycardia and profuse sweating were more frequent in patients given nefopam, and sedation was more intense with ketamine; however, the incidence of other potential complications did not differ among groups.

Making Progress in the Management of Postoperative Pain: A Review of the Cyclooxygenase 2–Specific Inhibitors

Postoperative pain is one of the most common forms of acute pain. Optimal pain management decreases the stress response to surgery, reduces complications, improves recovery time, and results in improved economic and quality-of-life outcomes. A preoperative, multimodal approach to postoperative analgesia can be achieved through a combination of therapies that continue beyond the immediate perioperative time frame. This multimodal approach provides superior analgesia with opioid-sparing effects and reduced opioid-related adverse events. Although the use of nonspecific nonsteroidal antiinflammatory drugs in a surgical setting has been limited owing to concerns of renal and gastrointestinal complications as well as platelet dysfunction, cyclooxygenase (COX)-2-specific inhibitors appear to be safe and effective alone and in combination with opioids for a variety of surgical procedures. The COX-2-specific inhibitors may have an important role in extending the use of balanced, multimodal analgesia to a broad surgical population, thus ultimately improving patient outcomes after surgery.

Anesthesia of the critically ill equine patient

There is a plethora of information regarding anesthetic management of horses; however, controlled studies of the critically ill equine patient are few. These patients should be managed like any equine anesthetic candidate but much more stringently:I. Preoperative evaluation and appropriate therapy may represent the difference between life and death during the intraoperative and recovery periods. 2. The anesthetic induction and maintenance protocol should be based on the individual situation of the veterinary facility and personnel("comfort zone"). 3. Appropriate monitoring and intraoperative supportive measures are essential. 4. The anesthetic period is a significant perturbation to homeostasis. Even if the horse seems to have done well (ie, as indicated by the cardiopulmonary values), a problem-free anesthetic period does not guarantee a successful recovery, and close monitoring should continue until the horse is ambulatory. 5. Critically ill patients are often in a negative energy balance. Supportive measures to ensure an adequate caloric intake, such as enteral or parenteral nutrition, facilitate healing and return of homeostasis.

Patients’ Global Evaluation of Analgesia and Safety of Injected Parecoxib for Postoperative Pain: A Quantitative Systematic Review

Parecoxib is the only parenterally administered cyclooxygenase-2-selective inhibitor available. We performed a systematic review, including full reports of randomized comparisons of parecoxib compared with any other analgesic intervention for prophylaxis or treatment of postoperative pain. Dichotomous data on patients' global evaluation of their analgesic regimen were extracted by means of the fraction of patients who rated their medication as "good" or "excellent." For safety analysis, data on any reported adverse effects were extracted. Relative risk (RR), number needed to treat (NNT), or number-needed-to-harm were calculated with 95% confidence intervals (CI). Data from 9 trials of 50 initially screened were finally analyzed. One thousand thirteen patients were randomized to receive parecoxib, 218 patients were allocated to an active control, and 507 patients received a placebo. With prophylactic administration, the pooled NNT to obtain the desired outcome ("good"/"excellent" rating) with parecoxib 20 and 40 mg compared with placebo was 4.5 (RR, 1.42; 95% CI, 0.91-2.24) and 4.0 (RR, 1.40; 95% CI, 1.10-1.79), respectively. In the treatment trials, the NNT to obtain the outcome of interest with parecoxib 20 mg was 2.1 (RR, 3.44; 95% CI, 1.49-7.96), 5.3 (RR, 1.43; 95% CI, 1.01-2.02), and -8.3 (RR, 0.85; 95% CI, 0.75-0.97) for the comparisons with placebo, morphine, and ketorolac, respectively. The corresponding NNT for treatment with parecoxib 40 mg was 1.7 (RR, 4.65; 95% CI, 2.04-10.61), 3.7 (RR, 1.62; 95% CI, 1.21-2.16), and 50 (RR, 1.03; 95% CI, 0.89-1.18) for the comparisons with placebo, morphine, and ketorolac, respectively. Overall adverse effects for parecoxib 20 and 40 mg were not different from those with placebo, morphine, or ketorolac. These results suggest a favorable profile for parecoxib compared with inactive or active controls. The optimal dose, timing, and frequency of administration need to be determined.

Establishing a nurse-based, anesthesiologist-supervised inpatient acute pain service: Experience of 4,617 patients

STUDY OBJECTIVE

To describe our nurse-based Acute Pain Services (APS) and present the results of 4617 patients treated by our service.

DESIGN

Descriptive audit.

SETTING

Large referral hospital.

PATIENTS

4617 patients treated by the APS.

MEASUREMENT AND MAIN RESULTS

Analgesic regimens [basic pain treatment, patient-controlled analgesia (PCA), epidural analgesia, spinal analgesia, and wound instillation], as well as the associated patient monitoring and event-response algorithms are detailed. The mean visual analog score (VAS) for pain was low. A VAS for pain greater than 30 mm was noted in 15.3% of all pain scores recorded. Bradypnea (respiratory rate < 10 breaths/min) was recorded in 19 patients (overall incidence = 0.4%). No complications resulting in sustained morbidity or mortality occurred. Of the patients, 96% described their overall satisfaction with the APS as either good or excellent.

CONCLUSION

A nurse-based APS provides effective and safe postoperative pain management.

Early bioavailability of paracetamol after oral or intravenous administration

BACKGROUND

Paracetamol is a peripherally acting analgesic commonly used in multimodal post-operative pain management to reduce the need for more potent analgesics with their unwanted side-effects. The dose and optimal galenical form for achieving analgesic concentrations is not well defined. The primary aim of this pilot project was to study the early bioavailability for two fixed doses of orally administrated paracetamol and one dose of intravenous propacetamol, all of which were given after minor surgery.

METHODS

Thirty-five patients undergoing day surgery were divided into five groups, seven patients each. Groups received either 1 g of an ordinary paracetamol tablet, 2 g of an ordinary paracetamol tablet, 1 g of a bicarbonate paracetamol tablet, 2 g of a bicarbonate paracetamol tablet or 2 g intravenously of prodrug propacetamol. We studied the plasma concentration of paracetamol during the first 80 min after administration.

RESULTS

Within 40 min, intravenous propacetamol gave a median plasma paracetamol concentration of 85 micromol/l (range 65-161) and decreased thereafter. After oral administration, median plasma paracetamol concentration increased with increasing dose and time, but there were huge inter-individual differences at all time points studied. At 80 min after oral paracetamol the median plasma concentrations were 36 and 129 micromol/l for the 1- and 2-g groups, respectively, with an overall range between 0 and 306 micromol/l.

CONCLUSION

Oral administration of paracetamol as part of multimodal pain management immediately post-operatively resulted in a huge and unpredictable variation in plasma concentration compared with the intravenous administration.

[Opioid-induced hyperalgesia. Pathophysiology and clinical relevance]

Opioids are the drugs of choice for the treatment of moderate to severe acute and chronic pain. However, clinical evidence suggests that opioids can elicit increased sensitivity to noxious stimuli suggesting that administration of opioids can activate both pain inhibitory and pain facilitatory systems. Acute receptor desensitization via uncoupling of the receptor from G-proteins, up-regulation of the cAMP pathway, activation of the N-methyl-D-aspartate (NMDA) receptor system, as well as descending facilitation, have been proposed as potential mechanisms underlying opioid-induced hyperalgesia. Numerous reports exist demonstrating that opioid-induced hyperalgesia is observed both in animal and human experimental models. Brief exposures to micro-receptor agonists induce long-lasting hyperalgesic effects for days, which might by reflected by clinical observations that large doses of intraoperative micro-receptor agonists increased postoperative pain and morphine consumption. Furthermore, the prolonged use of opioids in patients often requires increasing doses and may be accompanied by the development of abnormal pain. Successful strategies that may decrease or prevent opioid-induced hyperalgesia include the concomitant administration of drugs like NMDA-antagonists, alpha(2)-agonists, or non-steroidal anti-inflammatory drugs (NSAIDs), opioid rotation or combinations of opioids with different receptor selectivity.

Isobolographic analysis of interaction between cyclooxygenase inhibitors and tramadol in acetic acid-induced writhing in mice

Non-steroidal anti-inflammatory drugs (NSAIDs) and opioids are the most commonly used analgesics in the management of acute and chronic pain. Combined use of NSAIDs and opioids has been indicated for achieving better analgesia with reduced side effects. The present study was aimed at evaluating the combination of different NSAIDs, which inhibit cyclooxygenase (COX) enzymes and tramadol against acetic acid-induced writhing in mice. The expected beneficial effect of combination regimen was analyzed by isobolographic analysis. The oral and intrathecally administered tramadol, a mu-opioid and naproxen, a nonselective COX inhibitor produced dose-dependent antinociception, however, rofecoxib, a selective COX-2 inhibitor lacked analgesic efficacy in writhing test. Isobolographic analysis showed synergistic or supra-additive interactions for the combinations of naproxen and tramadol after oral and intrathecal administration. However, similar interaction was not observed when tramadol was combined with rofecoxib. Pretreatment with naloxone partially reversed the antinociceptive effect of tramadol per se and its combination with naproxen without modifying the per se effect of NSAID. The results demonstrated marked synergistic interaction between naproxen and tramadol and such interaction involved opioid as well as non-opioid mechanisms of tramadol and inhibition of COX-1 but not COX-2 by naproxen.

Postoperative Analgesia After Total Knee Replacement: The Effect of an Obturator Nerve Block Added to the Femoral 3-in-1 Nerve Block

Femoral nerve block (FNB) does not consistently produce anesthesia of the obturator nerve. In this single-blind, randomized, controlled study we added a selective obturator nerve block (ONB) to FNB to analyze its influence on postoperative analgesia after total knee replacement (TKR). Before general anesthesia, 90 patients undergoing TKR received FNB (Group 1), FNB and selective ONB (Group 2), or placebo FNB (Group 3). Postoperative analgesia was further provided by morphine IV via patient-controlled analgesia. Analgesic efficacy and side effects were recorded in the first 6 h after surgery. Adductor strength decreased by 18% +/- 9% in Group 1 and by 78% +/- 22% in Group 2 (P < 0.0001). Total morphine consumption was reduced in Group 2 compared with Groups 1 and 3 (P < or = 0.0001). Patients in Group 2 reported lower pain scores than those in Groups 1 and 3 (P = 0.0003). The incidence of nausea was more frequent in Groups 1 and 3 (P = 0.01). We conclude that FNB does not produce complete anesthesia of the obturator nerve. Single-shot FNB does not provide additional benefits on pain at rest over opioids alone in the early postoperative period. The addition of an ONB to FNB improves postoperative analgesia after TKR.

Pain management in ambulatory surgery

Successful ambulatory surgery is dependent on analgesia that is effective, has minimal adverse effects, and can be safely managed by the patient at home after discharge. A number of studies have identified that the provision of effective postoperative analgesia is inadequate for a significant proportion of patients. The following discussion details the current available analgesic options for ambulatory surgery patients and the rationale for their use. Preemptive analgesia should be given to all patients unless there are specific contraindications. Consideration should be given to the use of long-acting oral COX-2 selective nonsteroidal anti-inflammatory drugs (NSAIDs) and long-acting oral opioids to treat postoperative pain. A standardized multimodal postdischarge analgesic regimen tailored to the patient's expected postoperative pain levels should be prescribed. Patient follow-up by telephone questionnaire will confirm those surgical procedures that result in mild or moderate-to-severe postoperative pain and the effectiveness of treatment plans.

Prevalence and characteristics of pain in dogs and cats examined as outpatients at a veterinary teaching hospital

OBJECTIVE

To determine prevalence of pain among dogs and cats examined as outpatients at a veterinary teaching hospital and characteristics of pain in dogs and cats with evidence of pain.

DESIGN

Cross-sectional study.

ANIMALS

1,153 dogs and 652 cats examined as outpatients at The Ohio State University during 2002.

PROCEDURE

A questionnaire was administered to owners of all dogs and cats. For dogs and cats with evidence of pain, the cause, signs, anatomic location, type (superficial somatic, deep somatic, or visceral), duration, and severity of the pain and the principle mechanism (inflammatory, neuropathic, both, or unknown) responsible for the pain were determined on the basis of questionnaire responses and results of physical examination. The presence of primary hyperalgesia, secondary hyperalgesia, allodynia, and hyposensitivity was recorded.

RESULTS

231 (20%) dogs and 92 (14%) cats had evidence of pain. Dogs with evidence of pain were significantly older and heavier than dogs without. Cats with evidence of pain were significantly older than cats without. In most dogs and cats with evidence of pain, the pain was determined to be of short duration (< 7 days), of mild or moderate severity, somatic, associated with primary hyperalgesia, and inflammatory. Analgesic drugs were frequently administered to dogs with chronic pain, but were not always considered effective.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that mild or moderate pain associated with inflammation may be seen in dogs and cats examined as outpatients. Older, heavier dogs and older cats were more likely to have evidence of pain.

Preoperative oral rofecoxib reduces postoperative pain and tramadol consumption in patients after abdominal hysterectomy

We designed this study to determine whether the administration of a preoperative dose of rofecoxib to patients undergoing abdominal hysterectomy would decrease patient-controlled analgesia (PCA) tramadol use or enhance analgesia. Sixty patients were randomized to receive either oral placebo or rofecoxib 50 mg 1 h before surgery. All patients received a standard anesthetic protocol. Intraoperative blood loss was determined. At the end of surgery, all patients received tramadol IV via a PCA-device. Pain scores, sedation scores, mean arterial blood pressure, heart rate, and peripheral oxygen saturation were assessed at 1, 2, 4, 6, 8, 12, and 24 h after surgery. Total and incremental tramadol consumption at the same times was recorded from the PCA-device. Antiemetic requirements and adverse effects were noted during the first postoperative 24 h. Duration of hospital stay was also recorded. The pain scores were significantly lower in the rofecoxib group compared with the placebo group at 6 times during the first 12 postoperative h (P < 0.05). The total consumption of tramadol (627 +/- 69 mg versus 535 +/- 45 mg; P < 0.05) and the incremental doses at 1, 2, 4, 6, 8, and 12 h after surgery were significantly more in the placebo group than in the rofecoxib group. There were no differences between groups in intraoperative blood loss, sedation scores, hemodynamic variables, peripheral oxygen saturation, antiemetic requirements, or adverse effects after surgery. The length of hospital stay was also similar in the groups. We conclude that the preoperative administration of oral rofecoxib provided a significant analgesic benefit and decreased the opioid requirements in patients undergoing abdominal hysterectomy.

IMPLICATIONS

This study was designed to determine whether the administration of a preoperative dose of rofecoxib to patients undergoing abdominal hysterectomy would decrease patient-controlled analgesia tramadol use or enhance analgesia. We conclude that the preoperative administration of oral rofecoxib provided a significant analgesic benefit and decreased the opioid requirements in patients undergoing abdominal hysterectomy.

What is the role of NSAIDs in pre-emptive analgesia?

NSAIDs inhibit the cyclo-oxygenase enzymes, and decrease peripheral and central prostaglandin production. In addition to reducing the inflammation that accompanies tissue injury, decreasing prostaglandin production attenuates the response of the peripheral and central components of the nervous system to noxious stimuli. Such a reduction in the response to pain can reduce the peripheral and central sensitisation induced by noxious stimuli, and reduce the pain experienced in response to subsequent noxious stimuli. These properties would seem to make NSAIDs ideal drugs to use in a pre-emptive fashion, where analgesics are administered prior to a noxious stimulus, such as surgery, with the expectation that reduction in peripheral and central sensitisation will lead to a decrease of pain.However, the available perioperative trials of pre-emptive NSAID use have yielded modest or equivocal results, and these may be due, in part, to controversy associated with the definition of pre-emptive analgesia and how to conduct the corresponding clinical trials. Although NSAIDs may have a limited ability by themselves to induce a pre-emptive analgesic effect, the available trials suggest how the perioperative use of these drugs may be made more effective. It is expected that NSAIDs will play an increasing role in multimodal analgesia and pain relief in general.

Analgesia and discharge following preincisional ilioinguinal and iliohypogastric nerve block combined with general or spinal anaesthesia for inguinal herniorrhaphy

BACKGROUND

Preincisional ilioinguinal and iliohypogastric nerve block (IINB) reduces postoperative analgesics after inguinal herniorrhaphy. The effect of an IINB on postoperative pain and discharge profile was therefore studied in day-surgery patients undergoing inguinal herniorrhaphy with general or spinal anaesthesia.

METHODS

Seventy ASA I-II adult patients scheduled for inguinal herniorrhaphy received an IINB before the surgical incision with 15 ml of 0.5% bupivacaine. In a randomized fashion half of them received general anaesthesia with spontaneous breathing via a laryngeal mask (GA-group) and the other half received spinal anaesthesia with 5 mg of bupivacaine diluted with sterile water to 2.5-ml volume (SPIN-group). In the postanaesthesia care unit (PACU), pain was assessed on a scale from 0 to 10 (VAS) and ketorolac 30 mg i.v. (VAS < 5), or fentanyl 0.05 mg i.v. (VAS > or = 5) was administered as scheduled. In the day surgery unit and at home the analgesic was a tablet of ibuprofen 200 mg + codeine 30 mg (VAS > or = 3).

RESULTS

Patients in the SPIN-group reported lower postoperative pain scores at 30, 60 min (P < 0.0001) and 120 min (P < 0.05) after surgery, and longer time to first analgesic use (P < 0.0001). Patients in the GA-group had a shorter time to discharge without voiding (P < 0.001) and with voiding (P < 0.05). After discharge, there were no significant differences between the groups regarding pain scores at rest and at walking, or the doses of analgesic. Adverse events were rare in both groups.

CONCLUSION

Only a relatively short immediate analgesic benefit could be demonstrated by a combination of IINB with spinal anaesthesia compared with IINB combined with general anaesthesia. The use of general anaesthesia facilitated an earlier postoperative discharge than spinal anaesthesia.

Acute pain management services have progressed, albeit insufficiently in Canadian academic hospitals

PURPOSE

Acute pain management services (APMS) evolved in response to the desire for improved management of postoperative pain. The management of postoperative pain received formal support from international organizations over the past decade and by 1993 half of the Canadian university-affiliated teaching hospitals had implemented an APMS. The purpose of this survey was to describe APMSs in Canadian academic institutions, with specific emphasis on postoperative analgesics, new analgesic methods, training and research.

METHODS

Between June 2000 and January 2001, 62 Canadian hospitals affiliated with the 16 Canadian university anesthesiology departments were sent a postal questionnaire.

RESULTS

Fifty of the 62 respondents returned a completed questionnaire representing a response rate of 81%. Eighty percent of the hospitals surveyed had at least 200 beds, 90% (45) had implemented an APMS. Anesthesiology was primarily responsible in all 45 hospitals with an APMS. The results presented are based on the 45 centres with an APMS.

CONCLUSION

Since the early 1990s the percent of Canadian academic hospitals with an APMS has increased from 53% to 92%. These figures are comparable to the United States. Greater collaboration from nursing and pharmacy, mandatory training for medical and nursing students and residents, and a standardized approach to continuous quality improvement remain necessary.

Altered hematologic profiles following donor right hepatectomy and implications for perioperative analgesic management

Living liver donors for adult liver transplant recipients undergo extensive liver resection. Partial donor hepatectomies may alter postoperative drug metabolism and hemostasis; thus, the risks and the benefits of pain management for this unique patient population may need to be reassessed. The safety and efficacy of combined epidural analgesia and field infiltration in our initial living liver donor group are presented. A thoracic epidural catheter was placed before general anesthesia in 2 female and 6 male donors (44.2 +/- 11.3 years old, mean +/- standard deviation [SD], range 26-56). At the end of surgery, incisions were infiltrated (bupivacaine 0.25%), and an epidural infusion was used (bupivacaine 0.1% + hydromorphone hydrochloride 0.02%). Clinical outcomes were followed for 5 days. The time sequence of pain intensity on a 0-10 visual analog scale clustered into 3 phases, the intensity of which differed significantly from each other (2.2 +/- 0.6, 0.69 +/- 0.2, and 2.37 +/- 0.3 respectively, P = 0.028). Right shoulder pain was observed in 75% of the donors. Sedation, pruritus, and nausea were minimal. Consistently maximal international normalized ratio elevation occurred at 17.6 +/- 7 hours postoperatively, then slowly declined. Platelet counts were lowest on day 3. No neurologic injury or local anesthetic toxicity was observed. This 2-site approach provided effective, safe, postoperative analgesia for our donors. Universally, coagulopathy ensued, indicating a potentially increased risk for epidural hemorrhage at epidural catheter removal and mandating close postoperative neurologic and laboratory monitoring. Research is needed to advance the understanding of postoperative coagulopathy and hepatic dysfunction in these donors to further optimize their perioperative management, including that of analgesia.

Effects of morphine, lidocaine, ketamine, and morphine-lidocaine-ketamine drug combination on minimum alveolar concentration in dogs anesthetized with isoflurane

OBJECTIVE

To determine the effects of constant rate infusion of morphine, lidocaine, ketamine, and morphine-lidocaine-ketamine (MLK) combination on end-tidal isoflurane concentration (ET-Iso) and minimum alveolar concentration (MAC) in dogs anesthetized with isoflurane and monitor depth of anesthesia by use of the bispectral index (BIS).

ANIMALS

6 adult dogs.

PROCEDURE

Each dog was anesthetized with isoflurane on 5 occasions, separated by a minimum of 7 to 10 days. Individual isoflurane MAC values were determined for each dog. Reduction in isoflurane MAC, induced by administration of morphine (3.3 microg/kg/min), lidocaine (50 microg/kg/min), ketamine (10 microg/kg/min), and MLK, was determined. Heart rate, mean arterial blood pressure, oxygen saturation as measured by pulse oximetry (Spo2), core body temperature, and BIS were monitored.

RESULTS

Mean +/- SD isoflurane MAC was 1.38 +/- 0.08%. Morphine, lidocaine, ketamine, and MLK significantly lowered isoflurane MAC by 48, 29, 25, and 45%, respectively. The percentage reductions in isoflurane MAC for morphine and MLK were not significantly different but were significantly greater than for lidocaine and ketamine. The Spo2, mean arterial pressure, and core body temperature were not different among groups. Heart rate was significantly decreased at isoflurane MAC during infusion of morphine and MLK. The BIS was inversely related to the ET-Iso and was significantly increased at isoflurane MAC during infusions of morphine and ketamine, compared with isoflurane alone.

CONCLUSIONS AND CLINICAL RELEVANCE

Low infusion doses of morphine, lidocaine, ketamine, and MLK decreased isoflurane MAC in dogs and were not associated with adverse hemodynamic effects. The BIS can be used to monitor depth of anesthesia.

Synergistic effects between codeine and diclofenac after local, spinal and systemic administration

This study was designed to evaluate the extent of the antinociceptive interaction between codeine and diclofenac at the local, spinal and systemic level. The effects of individual and fixed-ratio combinations of locally, spinally or orally given codeine and diclofenac were assayed using the formalin test in rats. Isobolographic analysis was employed to characterize the synergism produced by the combinations. Codeine, diclofenac and fixed-ratio codeine-diclofenac combinations produced a dose-dependent antinociceptive effect when administered locally, spinally or systemically. ED(30) values were estimated for the individual drugs and isobolograms were constructed. Theoretical ED(30) values for the combination estimated from the isobolograms were 422.2+/-50.5 microg/paw, 138.5+/-9.2 microg/rat, and 9.3+/-1.1 mg/kg for the local, spinal and oral routes, respectively. These values were significantly higher than the actually observed ED(30) values which were 211.1+/-13.6 microg/paw, 45.9+/-3.9 microg/rat, and 2.5+/-0.2 mg/kg, indicating a synergistic interaction. Systemic administration resulted in the highest increase in potency, being about fourfold, while spinal and local administration increased potency in two- and threefold, respectively. The fact that the highest synergism was observed after systemic administration suggests that the interaction is occurring at several anatomical sites. The results support the clinical use of this combination in pain management.

Spinal Mechanisms Contribute to Analgesia Produced by Epidural Sufentanil Combined with Bupivacaine for Postoperative Analgesia

When used alone, lipid-soluble epidural opioids are thought to produce analgesia supraspinally via systemic absorption. However, spinal opioids and local anesthetics have been shown to act synergistically at the spinal level in animal studies. We, therefore, tested the hypothesis that sufentanil requirements will be less when given epidurally than IV in patients simultaneously given epidural bupivacaine after major abdominal surgery. Forty patients were anesthetized with isoflurane and epidural bupivacaine for major abdominal surgery. After surgery, each was given a continuous epidural infusion of bupivacaine at a rate of 5 mg/h and sufentanil patient-controlled analgesia (PCA). In a randomized, double-blinded fashion, the sufentanil was given either epidurally or IV. PCA settings were the same in each group. For 60 hrs after surgery, the following variables were measured: pain scores at rest, during mobilization, and during coughing; extension of sensory block; side effects; and sufentanil consumption. Pain scores, extension of sensory block, and the incidence of side effects did not differ between the two groups. Consumption of sufentanil in the epidural group was half that of the IV group (48 h after surgery: 107 +/- 57 microg versus 207 +/- 100 microg for the epidural and IV groups, respectively; P < 0.05). We conclude that spinal mechanisms contribute to the analgesia produced by epidural sufentanil in combination with a local anesthetic.

IMPLICATIONS

When combined with epidural bupivacaine, the sufentanil requirement was 50% less when given epidurally than IV. Epidural sufentanil thus appears to have a spinal mechanism of action.

The role of epidural anesthesia and analgesia in surgical practice

OBJECTIVE

To review the potential and proven benefits and complications of epidural anesthesia/analgesia.

SUMMARY BACKGROUND DATA

Advances in analgesia/anesthesia have improved patient satisfaction and perioperative outcomes. Epidural anesthesia/analgesia is one of these advances that is gaining rapid acceptance due to a perceived reduction in morbidity and overall patient satisfaction.

METHODS

A MEDLINE search was conducted for all pertinent articles on epidural anesthesia/analgesia.

RESULTS

Retrospective, prospective, and meta-analysis studies have demonstrated an improvement in surgical outcome through beneficial effects on perioperative pulmonary function, blunting the surgical stress response and improved analgesia. In particular, significant reduction in perioperative cardiac morbidity ( approximately 30%), pulmonary infections ( approximately 40%), pulmonary embolism ( approximately 50%), ileus ( approximately 2 days), acute renal failure ( approximately 30%), and blood loss ( approximately 30%) were noted in our review of the literature. Potential complications related to epidural anesthesia/analgesia range from transient paresthesias (<10%) to potentially devastating epidural hematomas (0.0006%).

CONCLUSIONS

Epidural anesthesia/analgesia has been demonstrated to improve postoperative outcome and attenuate the physiologic response to surgery.

Intraoperative Intravenous Ketamine in Combination with Epidural Analgesia: Postoperative Analgesia After Renal Surgery

We designed this double-blinded, randomized, controlled study to evaluate the effect of small-dose ketamine IV in combination with epidural morphine and bupivacaine on postoperative pain after renal surgery. An epidural catheter was inserted, and the administration of morphine and bupivacaine was started before surgery. Forty patients were assigned to one of two groups (ketamine or control). The ketamine group was administered a ketamine bolus and infusion during surgery. The median visual analog pain scale (VAS) scores at rest were significantly lower in the ketamine group during the first 6 h (P < 0.01). VAS pain scores on coughing were also significantly lower in the ketamine group (P < 0.01). Cumulative postoperative total analgesic consumption was less in the ketamine group on Days 1 and 2 (P < 0.001). The first analgesic demand time was shorter in the control group (9.2 +/- 11.5 min) than in the ketamine group (22.3 +/- 17.1 min) (P < 0.0001). The incidence of nausea and pruritus was more frequent in the control group (P < 0.05). In conclusion, postoperative analgesia was more effective when spinal cord and brain sensitization were blocked by a combination of epidural morphine/bupivacaine and IV ketamine.

IMPLICATIONS

Renal nociception conducted multisegmentally by both the spinal nerves (T10 to L1) and the vagus nerve cannot be blocked by epidural analgesia alone. We demonstrated that IV ketamine had an improved analgesic or opioid-sparing effect when it was combined with epidural bupivacaine and morphine after renal surgery.

A comparison of three techniques for acute postoperative pain control following major abdominal surgery

STUDY OBJECTIVES

To compare the analgesic efficacy of a nonsteroidal antiinflammatory drug (NSAID) alone (basic pain treatment) with that of NSAID in conjunction with either intravenous (IV) patient-controlled analgesia (IV-PCA) or intermittent epidural morphine (epidural morphine), among patients recovering from major intraabdominal surgery; and to assess the fixed and variable costs of providing the respective acute pain treatment modalities.

DESIGN

Prospective, nonrandomized study.

SETTING

Postanesthesia care unit (PACU) and surgical departments of a large referral hospital.

PATIENTS

All patients (n = 358) treated by our Acute Pain Service (APS) who were recovering from major intraabdominal surgery (colectomy, cholecystectomy, colostomy, gastrectomy, splenectomy).

MEASUREMENTS AND MAIN RESULTS

The structure of our APS, analgesic regimens, and the associated patient monitoring and event-response algorithms are detailed. Data of 358 patients recovering from major intraabdominal surgery and treated according to one of the three treatment protocols were collected and analyzed. The cost of providing our APS and the nursing time required to monitor and treat patients in each treatment group were also calculated. The median visual analog scale (VAS) scores were low in all three treatment groups (23.5 mm vs. 6 mm vs. 4, for the basic pain treatment, IV-PCA, and epidural morphine groups, respectively). However, the median VAS was significantly (p < 0.04) lower among patients who received epidural morphine than either the IV-PCA or basic pain treatment groups. Similarly, the number of patients who had at least one episode of a pain VAS >30 mm was significantly (p < 0.04) lower in the epidural morphine group than either of the other two groups. The frequency of nausea and vomiting was similar among the groups. However, the frequency of postoperative pruritus was significantly (p < 0.001) higher in the epidural morphine group than the other two groups. Patient satisfaction was unaffected by group allocation. Institutional costs per patient and the nursing time required to provide the APS were lowest in the basic pain treatment group.

CONCLUSIONS

Considering the respective pain profiles, complication rates, and institutional costs associated with the three analgesic regimens analyzed, the basic pain Treatment alone constitutes a useful alternative to the other two analgesic regimens assessed.

Patient-controlled epidural analgesia: a prospective audit of epidural pethidine 4 mg/ml and ropivacaine 0.2% with fentanyl 2 micrograms/ml

A prospective audit of one hundred and forty-seven (147) Acute Pain Service (APS) patients, who received postoperative patient-controlled epidural analgesia (PCEA) using pethidine 4 mg/ml or ropivacaine 0.2% with fentanyl 2 micrograms/ml in general surgical or orthopaedic wards over a twelve-month period, is presented. Data were collected from APS observation charts over a 48-hour period postoperatively. We found no significant difference in postoperative analgesia or side-effects between pethidine and ropivacaine with fentanyl in orthopaedic or general surgical patients.

Epidural ketamine potentiates epidural morphine but not fentanyl in acute nociception in rats

Epidural opioids have been reported to provide superior analgesia in acute pain management. Despite the fact that the required doses are low, major side effects such as respiratory depression may still occur. In an effort to maximize analgesia and to minimize the rate of side effects, epidural NMDA receptor antagonists, especially ketamine, may be co-administered with opioids. This study investigated whether ketamine had beneficial effects on fentanyl- or morphine-induced antinociception in an acute pain model in rats. In male Wistar rats, an epidural catheter was placed under general anaesthesia. After 1 week the animals were subjected to the tail withdrawal reaction (TWR) test. After determination of the basal reaction latencies, fentanyl, morphine, ketamine or combinations of an opioid with ketamine were administered epidurally. TWR latencies were measured for up to 2h after treatment. Both opioids showed a dose related antinociceptive effect. Fentanyl had a fast onset and a short duration of action whereas the reverse was true for morphine. Ketamine exhibited only limited antinociceptive properties. In the combinations, ketamine improved morphine-induced antinociception both in terms of maximal possible effect (MPE) as well as in duration of action. The combination of fentanyl with ketamine did not result in any improvement, neither in terms of MPE nor in duration of action. Moreover, increasing doses of ketamine tended to decrease the MPE of various doses of fentanyl. These data confirm that ketamine, contrary to opioids, does not possess important antinociceptive properties in an acute test such as the TWR test. Furthermore, these data indicate that additive drugs such as ketamine may have different effects on different opioids.

Nonsteroidal anti-inflammatory drugs for postoperative pain: a focus on children

Pain is a common symptom after surgery in children, and the need for effective pain management is obvious. For example, after myringotomy, despite the brief nature of the procedure, at least one-half of children have significant pain. After more extended surgery, such as tonsillectomy, almost all children have considerable pain longer than 7 days. Nonsteroidal anti-inflammatory drugs (NSAIDs) are useful for postoperative pain management because surgery causes both pain and inflammation. Several pediatric studies indicate NSAIDs are effective analgesics in the management of mild and moderate pain. In the treatment of severe pain, NSAIDs should be given with acetaminophen (paracetamol) or opioids, and the use of an appropriate regional analgesic technique should be considered. NSAIDs are more effective in preventing pain than in the relief of established pain. Pain following surgery is best managed by providing medication on a regular basis, preventing the pain from recurring. This proactive approach should be implemented for any procedure where postoperative pain is the likely outcome. In children, the choice of formulation can be more important than the choice of drug. Intravenous administration is preferred for children with an intravenous line in place; thereafter mixtures and small tablets are feasible options. Children dislike suppositories, and intramuscular administration should not be used in nonsedated children. Ibuprofen, diclofenac, ketoprofen and ketorolac are the most extensively evaluated NSAIDs in children. Only a few trials have compared different NSAIDs, but no major differences in the analgesic action are expected when appropriate doses of each drug are used. Whether NSAIDs differ in the incidence and severity of adverse effects is open to discussion. Because NSAIDs prevent platelet aggregation they may increase bleeding. A few studies indicate that ketorolac may increase bleeding more so than other NSAIDs, but the evidence is conflicting. Severe adverse effects of NSAIDs in children are very rare, but it is important to know about adverse effects in order to recognize and treat them when they do occur. NSAIDs are contraindicated in patients in whom sensitivity reactions are precipitated by aspirin (acetylsalicylic acid) or other NSAIDs. They should be used with caution in children with liver dysfunction, impaired renal function, hypovolemia or hypotension, coagulation disorders, thrombocytopenia, or active bleeding from any cause. In contrast, it seems that most children with mild asthma may use NSAIDs.

Effects of NMDA receptor antagonists on opioid-induced respiratory depression and acute antinociception in rats

Although exogenous opioids alter the responses of animals to tissue-damaging stimuli and therefore are the cornerstone in the treatment of acute antinociception, they have profound side effects on ventilation. To diminish ventilatory effects, combination therapies have been advocated. Recent studies reported the effectiveness of the addition of N-methyl-D-aspartate (NMDA) receptor antagonists such as ketamine to morphine in the treatment of acute pain. However, NMDA receptors, together with non-NMDA receptors are known to be involved in the neurotransmission of inspiratory drive to phrenic motoneurons. Co-administration of NMDA and non-NMDA receptor antagonists has been shown to be deleterious to respiratory function. The present study investigated the hypothesis that the association of opioids and NMDA receptor antagonists may add to the impairment of respiratory parameters. In male Wistar rats, combinations of opioids (fentanyl or morphine) at antinociceptive doses and NMDA receptor antagonists (ketamine, 40 mg/kg, or dextromethorphan, 10 mg/kg) at subanesthetic doses were administered intraperitoneally. Antinociception was tested with the tail-withdrawal reaction (TWR) test, while the effect on respiratory parameters was investigated with blood-gas analysis. We found that, in rats, co-administration of NMDA receptor antagonists and opioids may result in an increased respiratory depression as compared to the opioids alone. The effect of the NMDA receptor antagonists on opioid-induced antinociception was limited.

Pharmacology of systemic analgesics

Systemic administration of analgesic drugs is still the most widely used method for providing pain relief in acute painful situations. Opioids may be selected on the basis of their physicochemical characteristics and their diffusion index to the brain. But in clinical practice, their very steep concentration-analgesic effect relationship remains a critical aspect of opioid therapy. Thus, small fluctuations in plasma concentrations of opioids may lead to profound fluctuations in analgesic effect when their plasma and effect-site concentrations are near the minimum effective analgesic concentration (MEAC). Combining drugs acting on different mechanisms of nociceptive modulation offers benefits from additive/synergistic effects and will decrease the incidence of their adverse effects. Evidence-based reviews showed that effective pain relief using non-opioid analgesics relied on paracetamol supplemented with non-steroidal anti-inflammatory drugs (NSAIDs). The role of COX-2 selective inhibitors (CSIs) in acute pain relief still requires further evaluation. NSAIDs, CSIs and paracetamol share the property of morphine sparing in situations of severe (post-operative) pain. CSIs may be beneficial in patients in whom post-operative bleeding is a major surgical risk as the effects of NSAIDs on coagulation may last for days. Finally, low-dose ketamine infusions remain a worthwhile addition to opioid therapy. Analgesic concentrations of ketamine are 1/5th to 1/10th the anaesthetic concentration and exert significant inhibition on N-methyl-d-aspartate (NMDA) receptor activation.

From pain research to pain treatment: the role of human experimental pain models

There is no objective measure of a complete pain perception; we can, however, measure different aspects of nociceptive processing and pain perception. Earlier, experimental pain models often only involved induction of cutaneous pain using a single stimulus modality. Recently new experimental models have been developed eliciting various modalities of deep and visceral pain which more closely resemble clinical pain conditions. It is imperative to use multi-modal and multi-structure pain induction and assessment techniques, because a simple model cannot describe the very complex and multi-factorial aspects of clinical pain. Furthermore, it is important to assess pain under normal and pathophysiological conditions. The importance of peripheral and central hyperexcitability for acute and chronic pain has been demonstrated in animals and, to some extent, in humans. However, in spite of our immense knowledge, we still do not know how to prevent and treat this hyperexcitability efficiently. Our understanding of nociceptive mechanisms involved in acute and chronic pain and the effects of anaesthetic drugs or combinations of drugs on these mechanisms in humans may also be expanded using human experimental models. This mechanism-based approach may help us to develop and test therapeutic regimes in patients with acute and chronic pain.

Patient-controlled bupivacaine wound instillation following cesarean section: the lack of efficacy of adjuvant ketamine

STUDY OBJECTIVE

To assess the analgesic efficacy of ketamine when administered as an adjuvant to bupivacaine for patient-controlled wound instillation following cesarean section.

DESIGN

Prospective, randomized, double-blind study.

SETTING

Large referral hospital.

PATIENTS

50 term parturients undergoing cesarean section.

INTERVENTION

In all cases, a standard spinal anesthetic was administered. On completion of the surgery, a multihole 20 G epidural catheter (B. Braun, Melsungen, Germany) was placed above the fascia such that the tip was sited at the point which demarcated 50% of the length of the surgical wound. Thereafter, the catheter was connected to a patient-controlled drug delivery device. The device was filled with either 0.125% bupivacaine (bupivacaine group) or 0.125% bupivacaine and ketamine (1 mg/mL) (bupivacaine-ketamine group). Postoperatively, wound instillation was performed via the patient-controlled analgesia device. During the first 6 postoperative hours, a co-investigator administered "rescue" morphine (2 mg IV). Thereafter, "rescue" dipyrone (1 g) was administered on patient request.

MEASUREMENTS AND MAIN RESULTS

At all time intervals, visual analog scale (VAS) for pain at rest, on coughing, and during leg raise were similar between the groups. All patients (100%) in both treatment groups received "rescue" morphine. Similarly, the number of doses of 2 mg "rescue" morphine administered was unaffected by patient randomization. The total "rescue" morphine administered during the first 6 postoperative hours was 11.2 +/- 4.6 mg versus 11.3 +/- 5.6 mg for the bupivacaine group and bupivacaine-ketamine group, respectively. The number of pump infusions during the 24-hour study period was 9 +/- 2 and 9 +/- 3 for the bupivacaine group and bupivacaine-ketamine group, respectively. The volume infused via the delivery device was similar between the groups (81 +/- 18 mL vs. 85 +/- 24 mL for the bupivacaine group and bupivacaine-ketamine group, respectively). Psychomental and cognitive function as measured by the Digit Symbol Substitution and Mini Mental Tests were unaffected by adjuvant ketamine administration. Patient satisfaction was similar between the groups.

CONCLUSION

Adjuvant local ketamine does not enhance bupivacaine-induced wound instillation following cesarean section.

Feline perioperative pain management

Veterinary surgeons today are performing increasingly complex and invasive feline surgical procedures. In light of this, it is crucial that perioperative pain management in these patients be a top priority. This article outlines pain physiology and pathophysiology, pain recognition and management strategies, relevant pharmacology, and techniques for local and regional analgesia in cats.

Valdecoxib is more efficacious than rofecoxib in relieving pain associated with oral surgery

Inhibition of the cyclooxygenase (COX)-2 enzyme has been shown previously to reduce pain and inflammation. Valdecoxib is a new highly selective COX-2 inhibitor with a rapid onset of action and significant analgesic properties. This study compared the analgesic efficacy of valdecoxib and rofecoxib in treating postoperative pain in patients undergoing oral surgery. This randomized, double-blind, placebo-controlled study compared the efficacy of 40 mg valdecoxib with that of 50 mg rofecoxib and placebo. Efficacy was assessed by the onset of analgesia, pain intensity levels, and pain relief over 24 hours, time-weighted sum of total pain, sum of pain intensity difference, the percentage of patients requiring rescue medication and experiencing regimen failure, and patients' global evaluation. Patients receiving valdecoxib experienced a significantly quicker onset of analgesia, significantly improved pain relief, and lower pain intensity compared with patients receiving rofecoxib and greater satisfaction with their study medication after a single dose. Valdecoxib also demonstrated efficacy that was superior to that of rofecoxib with respect to the percentage of patients requiring rescue medication or experiencing regimen failure (p < or =.05). Valdecoxib, rofecoxib, and placebo were equally well tolerated. This study demonstrates that valdecoxib provides significantly greater analgesic efficacy than rofecoxib in the management of pain after oral surgery.

Pain management after major orthopaedic surgery: current strategies and new concepts

Several recently developed analgesic techniques effectively control pain after major orthopaedic surgery. Neuraxial analgesia provided by epidural and spinal administration of local anesthetics and opioids provides the highest level of pain control; however, such therapy is highly invasive and labor intensive. Neuraxial analgesia is contraindicated in patients receiving low-molecular-weight heparin. Continuous plexus and peripheral neural blockades offer excellent analgesia without the side effects associated with neuraxial and parenteral opioids. Intravenous patient-controlled analgesia allows patients to titrate analgesics in amounts proportional to perceived pain stimulus and provide improved analgesic uniformity. Oral sustained-release opioids offer superior pain control and greater convenience than short-duration agents provide. Opioid dose requirements may be reduced by coadministration of COX-2-type nonsteroidal analgesics.

Tramadol/acetaminophen combination tablets for the treatment of osteoarthritis flare pain: a multicenter, outpatient, randomized, double-blind, placebo-controlled, parallel-group, add-on study

BACKGROUND

In a flare of osteoarthritis (OA) pain, increasing the dose of standard anti-inflammatory or routine analgesic drugs may not be practical because of an increased incidence of side effects. In patients achieving inadequate pain relief from traditional non-steroidal anti-inflammatory drugs (NSAIDs) or cyclooxygenase (COX)-2-selective inhibitors, it may be appropriate to add an analgesic agent with a different mechanism of action, thereby targeting multiple components of the pain pathway.

OBJECTIVE

The addition of tramadol/acetaminophen tablets to existing therapy was compared with the addition of placebo in the treatment of OA flare pain.

METHODS

This was a multicenter, outpatient, randomized, double-blind, placebo-controlled, parallel-group, add-on study. Patients received 1 or 2 tramadol/acetaminophen (37.5 mg/325 mg) tablets QID or matching placebo for 10 days in addition to ongoing NSAID or COX-2-selective inhibitor therapy. The primary outcome measures were average daily pain intensity and average daily pain relief scores from days 1 through 5.

RESULTS

Three hundred eight patients were randomized to tramadoUacetaminophen (n = 197) or placebo (n = 111) and were followed for up to 10 days. Patients had a mean (+/-SD) age of 60.1 +/- 9.87 years, and were predominantly female (71.8%) and white (87.7%). Their mean (+/- SD) pain visual analog score at baseline was 73.2 +/- 11.8 mm, and their mean pain intensity score was 2.4 +/- 0.5 (on a scale from 0 = none to 3 = severe). Average daily pain intensity and pain relief scores were significantly improved with tramadol/acetaminophen compared with placebo on the primary assessment of efficacy from days 1 through 5 (both, P < 0.001) and on the assessment of efficacy from days I through 10 (both, P < 0.001) Tramadol/acetaminophen was significantly superior to placebo on the patients' and physicians' overall assessments of medication (both, P < 0.001) and on 3 of 4 subscales (pain [P = 0.004], physical function [P = 0.013], and overall [P = 0.008]) of the Western Ontario and McMaster Universities Osteoarthritis Index Questionnaire. The most common treatment-emergent adverse events with tramadol/acetaminophen were nausea, vomiting, and dizziness. No serious adverse events were reported in the tramadol/acetaminophen group.

CONCLUSION

In this study, addition of tramadol/acetaminophen to NSAID or COX-2-selective inhibitor therapy was well tolerated and effective in the treatment of OA flare pain.

Valdecoxib, a COX-2-specific inhibitor, is an efficacious, opioid-sparing analgesic in patients undergoing hip arthroplasty

Opioid agents are highly effective analgesics after orthopedic surgery but are associated with several adverse effects. Valdecoxib is a new, highly selective cyclooxygenase (COX)-2-specific inhibitor with a rapid onset of action and significant analgesic properties that is being developed for the management of acute pain. The objective of this study was to demonstrate the opioid-sparing efficacy of valdecoxib as part of a multimodal treatment of pain associated with hip arthroplasty. This multicenter, multiple-dose, double-blind, parallel-group study compared the opioid-sparing effects, analgesic efficacy, and safety of 20- and 40-mg doses of valdecoxib twice daily with placebo in patients receiving morphine by patient-controlled analgesia after hip arthroplasty. Study medication was first administered 1 to 3 hours preoperatively. The total amount of morphine administered, pain intensity, and patient's global evaluation of study medication were assessed over a period of 48 hours. Patients receiving 20 or 40 mg valdecoxib twice daily required on average 40% less morphine than those receiving placebo after hip arthroplasty. Pain intensity levels and patient satisfaction were significantly improved in both valdecoxib groups compared with placebo. Valdecoxib and placebo were equally well tolerated. Pre- and postoperative administration of valdecoxib reduces the amount of morphine required for postoperative pain relief and provides greater analgesic efficacy compared with morphine alone. Thus, valdecoxib has significant clinical utility for acute pain management in orthopedic surgery patients.

Intraoperative single-shot "3-in-1" femoral nerve block with ropivacaine 0.25%, ropivacaine 0.5% or bupivacaine 0.25% provides comparable 48-hr analgesia after unilateral total knee replacement

PURPOSE

To compare analgesia after intraoperative single shot "3-in-1" femoral nerve block (FNB) in combination with general anesthesia using ropivacaine 0.25%, ropivacaine 0.5% with bupivacaine 0.25% for total knee replacement (TKR).

METHODS

We performed a randomized, double-blind study in 48 patients for elective TKR under general anesthesia. Patients were randomized to one of four groups (C: sham block, R1: "3-in-1" FNB using 30 mL of ropivacaine 0.25%, R2: "3-in-1" FNB using 30 mL of ropivacaine 0.5%, B: "3-in-1" FNB using 30 mL of bupivacaine 0.25%). Verbal pain score (VPS) both at rest and movement were assessed for 48 hr after TKR (0=none; 1=mild; 2=moderate; 3=severe). Total morphine consumption and its associated side effects, duration of hospitalization after operation were also compared.

RESULTS

There were no differences in patients' physical characteristics, intraoperative morphine usage, operation time, tourniquet time or length of hospitalization between the four groups. When compared with group C, the VPS was significantly lower in groups R1, R2 and B at one, four, eight, 24 and 48 hr after TKR (P <0.05). The morphine requirement of groups R1, R2 and B were also significantly lower when comparing with group C up to 48 hr postoperatively (P <0.05). There were no significant differences in VPS and postoperative morphine requirement at any time between groups R1, R2 and B.

CONCLUSION

"3-in-1" FNB with ropivacaine provided analgesia that was clinically comparable to that of bupivacaine up to 48 hr after TKR. Increasing the concentration of ropivacaine from 0.25% to 0.5% failed to improve the postoperative analgesia of "3-in-1" FNB.

Multimodal analgesia for postoperative pain control

Pain is one of the main postoperative adverse outcomes. Single analgesics, either opioid or nonsteroidal antiinflammatory drugs (NSAIDs), are not able to provide effective pain relief without side effects such as nausea, vomiting, sedation, or bleeding. A majority of double or single-blind studies investigating the use of NSAIDs and opioid analgesics with or without local anesthetic infiltration showed that patients experience lower pain scores, need fewer analgesics, and have a prolonged time to requiring analgesics after surgery. This review focuses on multimodal analgesia, which is currently recommended for effective postoperative pain control.