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

Fast-track concept for ambulatory anesthesia

Fast-tracking in the ambulatory setting refers to the ability to transfer suitably recovered patients from the operating room directly to the Phase II (step-down) recovery area, bypassing the postanesthesia care unit. This article describes the concept of fast-tracking after ambulatory surgery and reviews anesthetic techniques that have helped to facilitate this process. The prevention and management of postoperative pain and nausea are also discussed.

[Postoperative analgesia. Specificity in the elderly]

The necessity of an adapted, optimal postoperative analgesia in the elderly is widely recognised. Reduced physiological capacities must be taken into consideration during the perioperative period. Class I analgesics, such as paracetamol, are both safe and efficient, and can be used for basic analgesia. Non steroid anti-inflammatory drugs carry an increased iatrogenic risk in the elderly. Their benefits should always be considered with regard to their risk. Their dosage should be decreased by 40-60% in comparison to the standard adult doses. Opioids, though highly efficient, carry a higher risk of respiratory depression due to the increased sensitivity to this class of molecules in the elderly. Doses must be reduced by 50% of the standard adult dose in order to limit adverse events while maintaining an equivalent level of analgesia. Patient-controlled and spinal opioid analgesia can be used in elderly patients. However surveillance of both the state of consciousness and respiratory rate must be carried out hourly over a period ranging from 12 to 24 hours. Pulse oximetry can be of value. After orthopaedic surgery, perineural or peripheral analgesia should be favoured considering the excellent benefit-risk ratio. Close clinical monitoring is essential for providing safe and efficient analgesia in the elderly using the techniques currently at our disposal.

[Repercussion of postoperative pain, benefits attending to treatment]

Physiological responses to postoperative acute pain may impede organ functions (cardiovascular, pulmonary, coagulation, endocrine, gastrointestinal, central nervous system, etc). Pain alleviation improves patient's comfort, but also may minimise perioperative stress response, physiological responses and postoperative organ dysfunction, assist postoperative nursing and physiotherapy, enhance clinical outcome, and potentially shorten the hospital stay. Potent postoperative analgesia, especially by epidural route, may be associated with reduction in incidence and severity of many perioperative dysfunctions. Peridural analgesia using local anaesthetics is the best technique for decreasing postoperative stress after lower abdominal or lower limb surgery. Analgesia using either epidural or high doses of morphine may improve some cardiac variables such as tachycardia and ischaemia, but does not change the incidence of severe cardiac complications. For patients undergoing vascular or orthopaedic surgery, epidural analgesia can improve clinical outcome by preventing the development of arterial or venous thromboembolic complications. However, in comparative studies, the control groups did not receive adequate prophylactic treatment for thromboembolic complications. Epidural analgesia can hasten the return of gastrointestinal motility and shorten the hospital stay. Postoperative mental dysfunction is decreased using intravenous PCA morphine in the elderly. Epidural analgesia with local anaesthetics improves postoperative respiratory function but, for unknown reasons, these benefits are not associated with a decrease in respiratory complications. On balance, the mode of acute pain relief decreases adverse physiological responses and many intermediate outcome variables; however, there is inconclusive evidence that it affects clinical outcome. Major advances in postoperative recovery can be achieved by early aggressive perioperative care, including potent analgesia, early mobilisation and oral nutrition. As a result, the hospital stay may be shortened.

[Management of postoperative pain in surgical units]

In order to improve the management of postoperative pain many publications insist on progressive changes in care organization. The following list outlines steps to be taken for implementation of these changes: 1) an initial analysis of management of post-operative pain allows awareness of reforms to be proposed; 2) participation of health teams in special training in order to use evaluation tools and collect data (use of analgesics, adverse effects); 3) establishing policies and procedures: recovery room, guidelines for analgesic use and adverse effects; 4) notifying patient about the various procedures to be used in postoperative period--discussion with the patient during the preoperative interview; 5) current use of standard patient-controlled analgesia (PCA) and locoregional analgesia; 6) use of combined techniques in order to achieve a balanced analgesia; 7) implementing a quality assurance programme which should include analgesic effectiveness, patient satisfaction and prevention of complications; and 8) planning of an Acute Pain Service based on a clinical nurse co-ordinator which offers highly effective forms of postsurgical analgesia.

Effective analgesia after bilateral tubal ligation

Postpartum bilateral tubal ligation is a brief surgical procedure with minimal tissue injury, yet postoperative recovery times and analgesia requirements are often disproportionately large. To evaluate the analgesic efficacy of local anesthetic infiltration, 20 parturients scheduled for elective minilaparotomy and bilateral tubal ligation with either spinal or epidural anesthesia participated in this prospective, randomized, controlled, double-blind trial. All patients received IV metoclopramide 10 mg and ketorolac 60 mg intraoperatively, as well as preincisional infiltration of the infraumbilical skin incision with 0.5% bupivacaine. Infiltration of bilateral uterine tubes and mesosalpinx was performed with either 0.5% bupivacaine (n = 10) or isotonic sodium chloride solution (saline) (n = 10). IV meperidine (25 mg every 3 min as needed) was given to treat pain in the postanesthesia care unit (PACU). The total amount of meperidine administered in the PACU was significantly larger in the saline group than in the bupivacaine group. Pain scores at 30, 45, 60, 75, and 90 min postoperatively and on the seventh postoperative day were significantly lower in the bupivacaine group than in the saline group. During tubal ligation, infiltration of uterine tubes and mesosalpinx with 0.5% bupivacaine significantly enhanced analgesia both in the immediate postoperative setting and on the seventh postoperative day compared with infiltration with sodium chloride.

IMPLICATIONS

During bilateral tubal ligation with either spinal or epidural anesthesia, preemptive analgesia using IV ketorolac, IV metoclopramide, and infiltration of the incised skin and uterine tubes with 0.5% bupivacaine allowed 9 of 10 patients to recover with no pain, nausea, vomiting, or cramping and to maintain good analgesia for 7 days postoperatively.

The management of postsurgical pain in the elderly population

It is likely that the trend towards ever more aggressive surgery in elderly and possibly frail patients will continue, with the lifting of traditional age limits. Recent evidence has show that surgical trauma induces processes of nervous system sensitisation that contributes to and enhances postoperative pain and leads to chronic pain. This knowledge provides a rational basis for pro-active, pre-operative and post-operative analgesic strategies which can reduce the neuronal barrage associated with tissue damage. As well as a reduction or elimination of post-operative pain, an improvement in physiological variables, such as neuroendocrine stress responses and post-operative pulmonary function can be expected. Complete pain control cannot be achieved with a single agent or technique without significant serious adverse effects, a problem which is compounded in the elderly patient due to a combination of slower drug metabolism, decreased organ function and physiological changes in cardiovascular and respiratory reserves. A balanced analgesic regimen that includes an effective afferent block (regional analgesia) is more appropriate. By preventing postoperative pain and its associated neuroendocrine sequelae, major surgical procedures in traditionally unsuitable patients can be seriously considered.

Adding ketamine in a multimodal patient-controlled epidural regimen reduces postoperative pain and analgesic consumption

We designed this double-blind study to evaluate the effect of adding small-dose ketamine in a multimodal regimen of postoperative patient-controlled epidural analgesia (PCEA). Ninety-one patients, ASA physical status I-III, undergoing major surgery, received a standardized general anesthesia and epidural catheterization in an appropriate intervertebral space after surgery. A PCEA device was programmed to deliver a regimen of morphine 0.02 mg/mL, bupivacaine 0.8 mg/mL, and epinephrine 4 microg/mL, with the addition of ketamine 0.4 mg/mL (ketamine, n = 45) or without (control, n = 46). The mean visual analog pain scale (VAS) scores during cough or movement for the first 3 days after surgery were higher in the control group than in the ketamine group (P < 0.05), whereas the mean VAS score at rest for the first 2 days were higher in the control group than in the ketamine group (P < 0.05). Furthermore, patients in the control group consumed more multimodal analgesics than patients in the ketamine group for the first 2 days (P < 0.05). The sedation scores and the incidence of side effects (pruritus, nausea, emesis, sleep deprivation, motor block, and respiration depression) were similar between the two groups. We conclude that adding ketamine 0.4 mg/mL in a multimodal PCEA regimen provides better postoperative pain relief and decreases consumption of analgesics.

IMPLICATIONS

Many studies have evaluated one or a combination of two analgesics for postoperative pain control, but few have examined a multimodal approach using three or four different epidural analgesics. This study demonstrates an additive analgesic effect when ketamine is added to a multimodal analgesic treatment.

Comparison of intrathecal morphine and continuous femoral 3-in-1 block for pain after major knee surgery under spinal anaesthesia

Major knee surgery is associated with moderate or severe post-operative pain. Intrathecal morphine and continuous femoral 3-in-1 block were compared prospectively in 40 patients for pain after major knee surgery under spinal anaesthesia, with 4 mL isobaric 0.5% bupivacaine. In a random order, 20 patients received preservative free morphine 0.3 mg mixed with spinal bupivacaine. In 20 patients, following spinal anaesthesia with only bupivacaine, femoral 3-in-1 block was performed post-operatively with 0.5% bupivacaine 2 mg kg-1. The block was continued via a catheter with 0.25% bupivacaine 0.1 mL h-1 kg-1 until the next morning (24 h after induction of spinal anaesthesia). Intramuscular oxycodone was given as a rescue analgesic in all patients. Two patients from the femoral group were excluded due to technical failure. Three patients in the morphine group and one patient in the femoral group did not need any additional oxycodone. In the morphine group on average 2.8 (range 0-7) and in the femoral group 3.2 (0-5) additional doses of oxycodone were needed during the 24 h observation period. The mean pain scores were significantly lower in the morphine group at 9 and 12 h into the 24-h trial. Itching was seen only in the morphine group (40% of the patients). Other side effects were similar in the two groups. All patients were satisfied with their pain therapy. Both intrathecal morphine and femoral 3-in-1 block alone were insufficient for the treatment of severe pain after major knee surgery.

Oral medication for post-Caesarean analgesia

A regimen of morphine, paracetamol and aspirin administered orally was evaluated in 20 patients following Caesarean section; 18 of 20 reported no or mild impairment in their ability to care for their babies. There was a high level of satisfaction with 18 of 20 being very satisfied with their postoperative analgesia. There was a low incidence of side-effects with this regimen. It was acceptable to both patients and staff.

Subcutaneous tunnelling of epidural catheters for postoperative analgesia to prevent accidental dislodgement: a randomized controlled trial

The use of subcutaneous tunnelling to prevent movement of epidural catheters was examined in a prospective controlled trial. There were 113 patients in the standard group and 100 in the tunnelled group. The groups were similar with respect to age, sex and weight. There were 176 thoracic catheters, and 37 lumbar catheters. Mean duration of catheterization in the tunnelled group was 3.5 +/- 1.3 days and in the standard group, 3.1 +/- 1.5 days. In total, 60 catheters moved significantly from their initial position: 17 (28%) moved inwards and 43 (72%) moved outwards. 159 catheters were still functioning at the time of their removal, 76 standard and 83 tunnelled. This represents 67 and 83% of the two groups respectively. Subcutaneous tunnelling was shown to prevent clinically significant inwards (P = 0.043) and outwards (P = 0.0005) movement of epidural catheters and is more likely to result in a functional epidural blockade at the time of catheter removal (P = 0.0084).

A review of preemptive analgesia

Postoperative pain, although frequently encountered, is often undertreated. A new method of treating postoperative pain is preemptive analgesia, which seeks to prevent or diminish pain before it is caused. A variety of drugs may be used and include nonsteriodal anti-inflammatory drugs, local anesthetics, opioids, and ketamine. They may be given before, during, and after surgery through the oral, intramuscular, intravenous, epidural, intrathecal, and intra-articular routes.

Epidural analgesia: prospective audit of 1062 patients

A prospective survey of one thousand and sixty-two patients receiving epidural analgesia in surgical wards was undertaken over a two-year period. The duration of infusion ranged from one to fourteen days, with a mode of three days. There were 1131 episodes where a local anaesthetic and opioid mixture was used and 160 where opioids were used alone. Local anaesthetic was not used without opioids. 23% of catheters were removed prematurely because of catheter related problems including accidental dislodgement (13%) and skin site inflammation (5.3%). No epidural abscess or haematoma was identified. In 14% of the total number of episodes there was either no demonstrable block or complications occurred requiring a change of solution: 30% of this group were salvaged following intervention by the Acute Pain Service (APS). The incidence of respiratory depression was 0.24%. There was no case of delayed respiratory depression. Epidural analgesia can be used safely in surgical wards provided that regular review of the patients is undertaken. It must be anticipated however, that up to 20% of patients will not receive adequate analgesia for the first 48 hours postoperatively. The failure rate could be halved if accidental dislodgement of epidural catheters could be eliminated.

Severity and impact of pain after day-surgery

PURPOSE

To assess the intensity, duration and impact of pain after day-surgery interventions. Predictors of pain severity were also evaluated along with the quality of analgesic practices and patient satisfaction.

METHODS

Eighty-nine consecutive day-surgery patients completed self-administered questionnaires before leaving the hospital and at 24, 48 hr and seven days after discharge. The survey instrument was composed of 0-10 pain intensity scales, selected items of the Brief Pain Inventory, of the Patient Outcome Questionnaire and of the Barriers Questionnaire. Analgesic intake in hospital and at home was recorded along with the use of other pain control methods.

RESULTS

Forty percent of the patients reported moderate to severe pain during the first 24 hr after hospital discharge. The pain decreased with time but it was severe enough to interfere with daily activities in a substantial number of patients. The best predictor of severe pain at home was inadequate pain control during the first few hours following the surgery. More than 80% of the participants were satisfied with their pain treatment. However, one patient in four (25%) needed contact with a health care provider because of pain at home. Many patients (33% to 51%) reported that instructions about pain control were either unclear or non-existent on several aspects. Medication use was low overall. Thirty-two percent of the patients did not take any pain medication during the first 24 hr after discharge although almost half of them (46%) rated their pain > or = 4. The most common concerns patients had about using pain medication were fear of drug addiction and side effects.

CONCLUSION

The severity and duration of pain after day-surgery should not be underestimated. Aggressive analgesic treatment during the hospital stay should be provided along with take-home analgesia protocols and comprehensive patient education programs.

The effect of short-term continuous epidural morphine on postoperative pain after laparoscopic cholecystectomy

This study was undertaken to determine whether short-term continuous epidural analgesia using morphine would relieve pain after laparoscopic cholecystectomy. The authors retrospectively reviewed the clinical data of 182 cases who had undergone a laparoscopic cholecystectomy. These cases were divided into four groups according to their anesthetic modes as follows: a control group with general anesthesia only (n = 37); group I, general anesthesia combined with one shot of epidural morphine (n = 78); and group II, general anesthesia combined with continuous epidural analgesia using morphine (IIa for 12 h (n = 33); IIb for 8 h (n = 34)). The pain score on a four-category verbal scale and the frequency of analgesic use were investigated. There were no differences in the background characteristics of the patients among the groups, except for the duration of surgery (I vs IIa; P = 0.006). The pain scores were significantly different between the control group and the other groups. The frequency of analgesic use in the control group was also significantly higher than in the other groups. A tendency toward a higher frequency of analgesic use in group I, compared with that in groups IIa and IIb, was observed. These findings thus suggest that short-term continuous epidural analgesia using morphine can effectively relieve postoperative pain after a laparoscopic cholecystectomy.

Bupivacaine infiltration into the neurovascular bundle of the prostatic nerve does not improve postoperative pain or recovery following transvesical prostatectomy

PURPOSE

We assessed the effect of intraoperative bupivacaine infiltration into the neurovascular bundle of the prostatic nerve on postoperative pain and patient outcome.

MATERIALS AND METHODS

The study included 40 American Society of Anesthesiologists physical status I to III patients undergoing transvesical prostatectomy. Following surgical resection of the prostate the neurovascular bundle of the prostatic nerve was infiltrated with either 10 ml. bupivacaine 0.5% or saline. Postoperative pain intensity was assessed using a patient generated 100 mm. visual analog scale and a patient controlled analgesia device. Additional analgesic requirements, time to ambulation, length of hospitalization and return to normal activity were also recorded.

RESULTS

There were no differences in visual analog scale for pain, patient controlled analgesia demands or actual morphine delivered. Similarly, saline versus bupivacaine infiltration did not influence ambulation time (21.3 +/- 2.7 versus 25.0 +/- 11.8 hours, respectively), length of hospitalization (7.06 +/- 0.8 versus 7.11 +/- 0.6 days, respectively), return to normal activity (14.4 +/- 8.8 versus 14.2 +/- 8.2 days, respectively) or patient satisfaction. On postoperative days 1 and 2 more patients in the saline treatment group requested additional oral analgesia compared to the bupivacaine treatment group. However, no statistical difference was demonstrated.

CONCLUSIONS

Following transvesical prostatectomy, prostatic nerve blockade has no beneficial effects on postoperative pain or patient outcome.

Effectiveness of bupivacaine administered via femoral nerve catheter for pain control after anterior cruciate ligament repair

STUDY OBJECTIVE

To evaluate the quality of pain control achieved with continuous local anesthetic infusion via a femoral nerve catheter, and to determine the optimum concentration of bupivacaine necessary to maintain pain control after full surgical anesthesia is established with 0.5% bupivacaine.

DESIGN

Randomized, prospective study.

SETTING

Tertiary care teaching center.

PATIENTS

25 ASA physical status I and II patients scheduled to undergo arthroscopically-aided anterior cruciate ligament (ACL) reconstruction by one surgeon, and who were willing to accept a femoral nerve catheter for postoperative pain control.

INTERVENTIONS

All patients received general anesthesia with propofol/alfentanil (10 ml/1 ml) mixture and nitrous oxide/oxygen (60%/40%) mixture via endotracheal tube. After induction of general anesthesia, a femoral nerve catheter was inserted with the aid of a nerve stimulator, and 20 ml of 0.5% bupivacaine was administered. The surgery was completed in a standard manner and the patients were randomized into three groups for the concentration of local anesthetic to continue the pain relief into the recovery phase. On awakening, all patients were determined to have a functioning femoral nerve catheter. Group 1 received 0.0625% (n = 8) bupivacaine, Group 2 0.125% (n = 9) bupivacaine, and Group 3 0.25% (n = 8) bupivacaine; all doses were initiated in a blinded manner at 0.12 ml/kg/hr. Patients also received intravenous patient-controlled analgesia with morphine via demand mode only, with a 1.0 mg dose and a 6 minute lock-out interval.

MEASUREMENTS AND MAIN RESULTS

Pain was determined at defined intervals by visual analog scale (VAS). Data collected included demographics, VAS scores, and total morphine administered. All patients were pain-free on emergence from general anesthesia. No patient required parenteral opioid for pain control while in the postanesthesia care unit. There were no significant differences in pain scores among groups, and average pain scores (2.5 to 4.0) indicate good pain control throughout the entire hospitalization. There were no complications.

CONCLUSIONS

Low concentrations of bupivacaine delivered via femoral nerve catheter after an established femoral nerve block can provide excellent postoperative pain control after ACL reconstruction.

Pain Management

Postoperative pain management is essential and must be approached as an integral part of the perioperative care. It should be systematic and based on sound physiological and pharmacological principles. The intra operative management of pain is crucial, because there is perhaps an important role for preemptive analgesia. Because of its unique nature, pain is difficult to assess; for good results, adequate and repeated assessment are vital. The literature also points to the detrimental ef fects of inadequate pain control. There are a variety of methods available for pain management. In choosing a method, various factors need to be considered includ ing: (1) physician skill, (2) knowledge of analgesics and routes of administration, (3) patient and clinically re lated circumstances, (4) the availability of an environ ment supportive of effective pain management, and (5) the knowledge and skill of staff to assess and monitor patients. These need to be considered along with the risk-benefits and cost-benefit of the various drugs and techniques. The cornerstone of therapy is opioids, which can be administered by a variety of routes. The use of thoracic epidural analgesia (TEA) with opioids and local anesthetics is highly beneficial, especially in high-risk patients. The aim should be to provide all patients a balanced analgesic regimen based on the identification of multiple mechanisms involved in postoperative pain.

Isobolographic analysis of the interaction between epidural sufentanil and bupivacaine in rats

The present study was performed to evaluate the nature of the interaction between epidurally administered sufentanil and bupivacaine in producing antinociception in rats. Rats in which epidural catheters had been inserted received epidural injections with bupivacaine and sufentanil. Nociception was tested by use of the tail-withdrawal reaction (TWR) test and the hot-plate test. Isobolographic analyses were performed with fixed and variable dose ratio treatment schedules based on the ED50s and the highest inactive concentrations of the compounds in both tests. In the TWR test, a synergistic interaction was obtained between the two compounds independent of whether a variable dose ratio regimen (with either 0.08 microgram/rat sufentanil or 80 micrograms/rat bupivacaine as the preset component) or a fixed dose ratio of 1/1,000 sufentanil/bupivacaine (based on the individual ED50s) was used. In the hot-plate test, a synergistic interaction was observed only in the variable dose ratio regimen with 0.08 microgram/rat sufentanil as the preset component and in the fixed dose ratio regimen of 1/1,000 sufentanil/bupivacaine (a ratio based on the ED50 values of the TWR test) but not with a ratio of 1/200, as demonstrated by the ED50s of both drugs in the hot-plate test. The interaction between epidurally administered bupivacaine and sufentanil seems to be synergistic for both tests when variable and fixed dose ratios are used. The synergism could be more easily demonstrated in the TWR test. For drugs with a segmental action, the hot-plate test seems to be less optimal. The necessity of a minimal critical amount of bupivacaine to obtain synergism may have clinical implications.

Peri-operative multimodal pain therapy for caesarean section: analgesia and fitness for discharge

PURPOSE

To compare, the efficacy of a multi-modal analgesic regimen and single drug therapy with iv PCA morphine alter Caesarean delivery with spinal anaesthesia.

METHODS

Forty ASA 1-2 parturients presenting for elective Caesarean section were randomized to receive multimodal pain treatment with intrathecal morphine, incisional bupivacaine and ibuprofen+acetaminophen po until hospital discharge (Group 1) or conventional therapy with iv PCA morphine weaned to acetaminophen+codeine po (Group 2). Both groups received spinal anaesthesia with 1.7 ml hyperbaric bupivacaine 0.75%. Visual analog pain scores at rest (RVAPS) and with movement (DVAPS) were recorded q 2 hr during the first 24 hr, then q 4 hr until discharge. Time to first walking, eating solid food, flatus, bowel movement, voiding and hospital discharge were recorded.

RESULTS

Pain scores were lower in Group 1 patients during the first 24 hr after spinal injection RVAPS 0.6 +/- 0.1 in Group 1 vs 2.1 +/- 0.1 in Group 2 (mean +/- SEM), DVAPS 1.9 +/- 0.1 in Group 1 vs 4.1 +/- 0.1 in Group 2 (P < 0.0001). Times to first flatus, 36.1 hr +/- 2.9 vs 20.5 +/- 1.8 (P < 0.05) and to first bowel movement, 74.8 hr +/- 5.6 vs 57.4 +/- 4.7 (P < 0.0001) were longer in Group 2 patients. There was no difference between groups in time to eating solid food, walking or hospital discharge.

CONCLUSION

Multi-modal pain therapy resulted in improved early post-operative analgesia during the first 24 hr after Caesarean delivery. Patients receiving iv PCA morphine followed by acetaminophen+codeine po were more likely to develop decreased bowel mobility. All patients, with one exception, achieved discharge criteria (eating solid food, absence of nausea, normal lochia, dry incision and DVAPS < 4) at 48 hr after spinal injection.

Postoperative analgesia with i.v. propacetamol and ketoprofen combination after disc surgery

PURPOSE

The concept of balanced analgesia suggests that a combination of analgesic drugs may enhance analgesia and reduce side effects after surgery. This study evaluated the effect of the combination of propacetamol (Prodafalgan) and ketoprofen (Profenid) after surgery of a herniated disc of the lumbar spine.

METHODS

After randomization, 60 patients received: placebo (group 1); 2 g propacetamol (group 2); 50 mg ketoproten (group 3); or a combination of 2 g propacetamol and 50 mg ketoprofen (group 4). Drugs were administered every six hours for two days after surgery. The patients used morphine with patient controlled analgesia pumps (bolus 1 mg; lock out time 10 min) and were evaluated with a visual analogue scale (VAS) at rest and movement every six hours for two days. Side effects were noted.

RESULTS

The patient characteristics and surgery were identical for each of the four groups. The VAS scores throughout the study were lower in group 4 than in groups 1, 2 and 3 both at rest (P < 0.05) and on movement (P < 0.01). The cumulative dose of morphine at 48 hr was lower in group 4 than in group 1 (23.4 +/- 5 mg vs. 58.9 +/- 9 mg; P < 0.01) or group 2 (23.4 +/- 5 mg vs 43.4 +/- 6.6 mg; P < 0.05) and similar to that in group 3 (34.2 +/- 4.5 mg). The incidence of side effects was similar in all groups.

CONCLUSION

The combination of propacetamol and ketoprofen reduced pain scores both at rest and on movement. The drug combination did not reduce the morphine consumption and incidence of side effects.

Recent advances in our understanding of pain: how should they affect management?

Pain management continues to challenge the clinical veterinarian. It is important to appreciate that pain is not a monolithic syndrome; many variables associated with pain origin, transmission, perception, and response must be understood in order to provide the best pain relief in a clinical patient. Rational pain management requires an understanding of underlying mechanisms involved in pain and an appreciation of how analgesic agents act to disrupt them. The goal of this presentation is to acquaint you with the fundamentals associated with pain physiology and how clinical pain management may modify these mechanisms to benefit the patient.

Management of acute and surgical pain

Effective treatment of acute pain secondary to surgery and trauma is often a complex and perplexing task. Concern about potential adverse effects of analgesic drugs on cardiovascular, respiratory, renal, and central nervous system functions often limits the use of analgesics in the very patients that could benefit from them the most. Combining drugs of different classes and with different mechanisms of action is an established anesthesia technique used to achieve a desired effect with a minimum of adverse side effects. Similarly, the use of a balanced or multimodal approach to the treatment of acute pain can greatly enhance the clinician's ability to safely provide effective analgesia. Systemic opioids, alpha-2 agonists, nonsteroidal antiinflammatory drugs, and local or regional analgesic techniques can be used in varying combinations to meet the needs of the painful animal and hasten recovery.

Comparison of epidural morphine and oxycodone for pain after abdominal surgery

STUDY OBJECTIVE

To compare the efficacy and side effects of epidural morphine and oxycodone for pain following major abdominal surgery.

DESIGN

Randomized, double-blind study.

SETTING

4th Department of Surgery, Helsinki University Central Hospital.

PATIENTS

44 adult ASA physical status I, II, and III patients scheduled for elective major abdominal surgery.

INTERVENTIONS

Thirty-three patients were allocated randomly to one of two epidural groups and 11 patients received oxycodone intravenously (IV). The two epidural groups received either morphine (bolus 0.015 mg/kg followed by an infusion 0.003 mg/kg/hr) or oxycodone (bolus 0.15 mg/kg followed by an infusion 0.03 mg/kg/hr) before induction of standardized anesthesia and for 24 hours thereafter. A third group of patients was given the same dose of IV oxycodone as in the epidural group, serving as an open control group for epidural oxycodone.

MEASUREMENTS AND MAIN RESULTS

Blood samples were drawn for plasma opioid concentrations. Postoperatively, pain (at rest and during coughing), nausea, pruritus, sedation, respiratory rate, and hemodynamics were recorded until the end of the infusions. The epidural dose ratio between morphine and oxycodone was 1:8.4 to 9.8 to provide similar analgesia. Side effects occurred similarly in the three groups. Mild respiratory depression was seen in all groups, especially in the IV oxycodone group. In all groups, hemodynamic variables remained within normal limits.

CONCLUSIONS

In the dosages reported, oxycodone can be used epidurally for acute post-operative pain. The analgesic effect was as good as that of epidural morphine.

The antinociceptive effect of epidural lignocaine and fentanyl during lithotripsy

To determine the antinociceptive effect of combining epidural fentanyl with lignocaine during non-immersion lithotripsy, 56 healthy patients were enrolled into a prospective, randomized, double-blind study. Epidural anaesthesia was induced with either lignocaine 300 mg alone, or lignocaine 300 mg, or 200 mg in combination with fentanyl 100 micrograms. Throughout the procedure analgesia was assessed by comparing the incidence of (a) spontaneous complaints of pain, (b) patients' attempts to withdraw from the painful stimulus, (c) supplemental epidural lignocaine requirements, (d) the haemodynamic response to lithotripsy and (e) the time to first postoperative pain. The patients who received the fentanyl-lignocaine 300 mg combination required no supplemental lignocaine, experienced marginally less intraoperative pain and recorded lower mean arterial blood pressures when compared with lignocaine 300 mg alone. However, when the combination of lignocaine 200 mg and fentanyl 100 micrograms was administered, patients experienced significantly more pain, withdrew from the painful stimulus more often and received more supplemental lignocaine when compared with the other two treatment groups. No difference was found in the time to the first complaint of postoperative pain. Similarly, discharge times were unaffected by treatment modality. We conclude that despite the addition of fentanyl, adequate analgesia during lithotripsy is dependent upon the dose of local anaesthetic administered.

Determination of the minimum local analgesic concentration of epidural chloroprocaine hydrochloride in labor

The aim was to determine the effective concentration in 50% of patients (EC(50)) of chloroprocaine in the first stage of labor. A constant dose modification of a model where EC(50) was previously defined as the minimum local analgesic concentration (MLAC) was used. Parturients (n = 36) requesting epidural analgesia in labor, at cervical dilatation not exceeding 7 cm, were enrolled into this prospective, double-blinded study. After placing a lumbar epidural catheter, chloroprocaine 150 mg diluted to the concentration being evaluated was given. The concentration was determined by up-down sequential allocation. The volume of the bolus ranged from 15 to 50 ml. Efficacy was assessed using 100 mm visual analogue pain scores with 10 mm or less within 30 min defined as effective. MLAC (95%CI) was 0.42%w/v (0.34 to 0.5) using the formula of Dixon & Massey and as a sensitivity test was 0.4%w/v (0.35 to 0.46) using probit regression analysis. In conclusion, MLAC of chloroprocaine was 0.42%w/v in these parturients, equivalent to 14 millimolar solution. This study confirmed that concentration rather than dose could be used as a measure of efficacy in this constant dose model.

Intravenous ketamine or fentanyl prolongs postoperative analgesia after intrathecal neostigmine

The purpose of this study was to determine whether intravenous (i.v.) ketamine would enhance analgesia from intrathecal (IT) neostigmine compared with combining i.v. fentanyl with IT neostigmine. Sixty patients undergoing vaginoplasty under spinal anesthesia were assigned to one of six groups (n = 10). Patients were premedicated with midazolam plus the i.v. test drug. The IT drugs were 20 mg bupivacaine plus saline or 50 micrograms neostigmine. The control group (CG) received saline i.v. and IT. The neostigmine control group (NCG) received saline i.v. and neostigmine IT. The ketamine group (KG) received ketamine 0.2 mg/kg i.v. and saline IT, and the ketamine neostigmine group (KNG), ketamine i.v. and neostigmine IT. The fentanyl group (FG) received fentanyl 1 microgram/kg i.v. and saline IT, and the fentanyl neostigmine group (FNG), fentanyl i.v. and neostigmine IT. The time to first rescue analgesic was longer for the FNG and KNG compared with the CG, with less rescue analgesic consumption (P < 0.02 and P < 0.01, respectively). Only the FNG had significantly intraoperative nausea/vomiting (P < 0.02). In conclusion, the combination of i.v. ketamine and IT neostigmine results in prolonged postoperative analgesia and less intraoperative nausea and vomiting than the combination of i.v. fentanyl and IT neostigmine.

Postoperative opioid analgesia: time for a reconsideration?

Postoperative pain relief has improved in recent years with the development of new analgesics, additional routes of administration and the appearance of the hypothesis of preemptive as well as balanced analgesia (Kehlet H; Postoperative pain relief-what is the issue? Br J Anaesth 1994;72:375-8). Many initial improvements simply involved the administration of opioid analgesics in new ways, such as continuous or on demand intravenous (i.v.) or epidural infusion. These methods allow lower total opioid dosages, provide a more stable concentration of opioid at the receptor and correspondingly better analgesic effects, and also fewer unwanted side effects. Although opioids have played a prominent role in postoperative analgesia for centuries and are still often administered as a matter of routine, their frequent minor side effects and the increasing availability of suitable alternatives may limit their future use in some situations. Thus, the recent emphasis on ambulatory surgery and accelerated surgical stay programs, both with a focus on early recovery of organ function and provision of functional analgesia [i.e., pain relief that allows normal function (Kehlet H: Postoperative pain relief-what is the issue? Br J Anaesth 1994;72:375-8)] provide an opportunity for a reappraisal of opioid use in these settings. For this debate, controlled clinical studies on the opioid-sparing effect of different analgesic techniques are mentioned, and preferably studies with multiple dosing of analgesics and/or a reasonably large patient sample size. These data do not allow a proper meta-analysis to be performed because of the large variability in surgical procedures, dosing regimens, assessment criteria, among others.

The analgesic efficacy and adverse effects of continuous epidural sufentanil and bupivacaine infusion after thoracotomy

We investigated analgesia and the adverse effects of epidural sufentanil infusion in a double-blind randomized study of 37 patients undergoing thoracic surgery. Sufentanil 1 microgram/mL was administered at a thoracic (Ts, n = 12) or lumbar level (Ls, n = 11), or combined with bupivacaine 1 mg/mL at a thoracic level (Tsb, n = 14). Postoperatively, the epidural infusion rate was titrated (4-20 mL/h) according to the visual analog pain scale when assessed during function (VAS-F) or the occurrence of side effects. When epidural analgesia failed, nonsteroidal antiinflammatory drugs (NSAIDs) were given. VAS-F was lowest in the Tsb group (Tsb < Ts = Ls) despite its having both the lowest rate of epidural infusion (Tsb < Ts < Ls) and need of additional NSAIDs (Tsb < Ts = Ls). Sedation (Tsb < Ts < Ls) and hypercapnia (Tsb = Ts < Ls) occurred most frequently in the Ls group. Vital capacity (VC) was reduced in all groups by 43%-58% (Ls > Ts) and had recovered only partially at 24 h after discontinuation of the epidural infusion. The slopes of the ventilatory response (minute ventilation [VE], inspiratory flow, and mouth occlusion pressure at 0.1 s [P0.1]) to 7% CO2 decreased during treatment in Ls, Ts, and Tsb groups at the most by 73%, 55%, and 52% (not significant [NS] between groups), 59%, 45%, and 38% (NS between groups), and 81%, 43%, and 18% (Ls > Tsb), respectively. Twenty-four hours after discontinuation of the epidural infusion, there was a complete recovery of the VE, inspiratory flow, and P0.1 response to CO2 in the Tsb group only. The study shows that, after thoracotomy, epidural sufentanil analgesia is optimal when tailored to the site of nociceptive input and combined with bupivacaine.

Ketorolac does not decrease postoperative pain in elderly men after transvesical prostatectomy

PURPOSE

To assess the postoperative analgesic efficacy and morphine-sparing effect of ketorolac in elderly patients.

METHODS

Sixty ASA-physical status I to III men, aged 60-88 yr, undergoing transvesical prostatectomy were studied according to a randomized, placebo controlled, double-blind study protocol. A standard general anaesthetic was administered. Thirty minutes before concluding the surgical procedure either ketorolac 60 mg or an equal volume of saline was administered, im. Postoperative pain was assessed hourly for six hours using a 100 mm visual analog score (VAS) and a patient-controlled analgesia (PCA) device.

RESULTS

Hourly PCA-demands, actual morphine delivered, and patient generated VAS pain scores were unaffected by the treatment modality. On conclusion of the study the total PCA morphine delivered was 11.9 mg +/- 1.38 and 10.8 mg +/- 1.52 for the saline and ketorolac groups, respectively.

CONCLUSION

The intraoperative administration of ketorolac, 60 mg, im, was not associated with postoperative morphinesparing or improved analgesia in this elderly population.

Prophylaxis against postoperative complications in gastroenterology

Gastrointestinal surgery results in pain, profound endocrine metabolic changes and organ dysfunction, immunosuppression and decreased resistance to infection, fatigue and convalescence. The main pathogenetic mechanism is the surgical stress response, which may be reduced by minimal invasive (laparoscopic) surgical techniques and afferent neural and perhaps humoral mediator blockade. Subsequently, these techniques have been documented as reducing a variety of postoperative morbidity parameters. A unifying concept for control of the postoperative period is presented as a combined effort to enhance preoperative information, stress reduction and sufficient functional pain relief allowing early mobilization and oral nutrition. Preliminary data, in combination with laparoscopic surgery, suggest that this approach improves outcome significantly.

Management of postoperative pain and emesis

As more extensive and painful surgical procedures (e.g., laparoscopic cholecystectomy, laminectomy, knee and shoulder reconstruction, hysterectomy) are being performed on an outpatient basis, the availability of sophisticated postoperative analgesic regimens are necessary to optimize the benefits of day-case surgery for both the patient and the health care provider. However, outcome studies are needed to evaluate the effects of these newer therapeutic approaches with respect to postoperative side effects, cost and important recovery variables. Recent studies suggest that factors other than pain per se must be controlled in order to reduce postoperative morbidity and facilitate the recovery process. Not surprisingly, the anaesthetic technique can influence the analgesic requirements and the likelihood of emesis in the early postoperative period. Although opioid analgesics will continue to play an important role, the adjunctive use of both local anaesthetic agents and NSAIDs will probably assume an even greater role in the future. Use of drug combinations (e.g., opioids with local anaesthetics, alpha2 agonists and/or NSAIDs) may provide for improved analgesia with fewer opioid-related side effects than narcotic analgesics alone. Finally, safer and simpler analgesic delivery systems are needed to improve our ability to provide cost-effective pain relief after day-case surgery in the future. In conclusion, as a result of our enhanced understanding of the mechanisms of acute pain and the physiological basis of nociception, the provision of "stress free" anaesthesia with minimal postoperative discomfort is now possible for most patients undergoing ambulatory surgical procedures. The aim of any analgesic technique should not only be to lower the pain scores but also to facilitate earlier mobilization and to reduce perioperative complications, in particular PONV. In future, clinicians should be able to effectively treat postoperative pain using a combination of "balanced," "preemptive," and "peripheral" analgesia techniques without producing emetic sequelae.

Rectal indomethacin potentiates spinal morphine analgesia after caesarean delivery

This double-blind, randomized study was designed to evaluate the use of indomethacin (Indocid, MSD) following caesarean delivery performed under spinal anaesthesia. Thirty ASA I-II women presenting for elective caesarean were recruited. Spinal anaesthesia was performed in a standard manner using hyperbaric bupivacaine, fentanyl and morphine. At the completion of surgery, subjects were administered two rectal suppositories, followed by 12-hourly suppositories for six doses (three days). The study group received 100 mg indomethacin suppositories and controls were given placebo (Anusol). Data collected included Visual Analog Scale (VAS) pain scores at rest and with movement, VAS scores for nausea and itch, and analgesic use. Demographic data were similar in the two groups. Median time to first analgesia (TTFA) was nine hours in the control group v. 39.5 hours in the indomethacin group (P < 0.003). Additional analgesic requests throughout the postoperative period were less in women who received indomethacin: 4 v 11 (P < 0.001). Women who received indomethacin had significantly less pain on the first postoperative day, especially on movement: mean VAS 1.4 v 5.1 (P < 0.00001). There were no reported adverse neonatal or maternal effects from the use of indomethacin. Rectal indomethacin use following caesarean delivery leads to significantly improved pain relief compared with placebo. The combination of spinal morphine and rectal indomethacin leads to high-quality postoperative analgesia.

Determination of the minimum local analgesic concentrations of epidural bupivacaine and lidocaine in labor

The aim of this study was to devise a clinical model to determine the effective concentrations in 50% of patients (EC50) for bupivacaine and lidocaine in the first stage of labor and define EC50 as the minimum local analgesic concentration (MLAC). This should allow the determination of relative analgesic potency and, subsequently, the local anesthetic sparing efficacy of other epidural analgesics. Parturients not exceeding 5 cm cervical dilation who requested epidural analgesia were enrolled. The two studies involved 81 women (bupivacaine n = 41, lidocaine n = 40). After a lumbar epidural catheter was placed, 20 mL of the concentration of local anesthetic being tested was given. The concentration was determined by the response of the previous patient to a higher or lower concentration using double-blinded, up-down sequential allocation. Efficacy was assessed using 100-mm visual analog pain scores with less than 10 mm within 1 h defined as effective. MLAC was determined using the formula of Dixon and Massey. Results show MLAC bupivacaine 0.065% (95% confidence interval [CI] 0.045-0.085), MLAC lidocaine 0.37% (95% CI 0.32-0.42), equivalent to 2 and 14 mmol solutions, respectively. Thus bupivacaine was 5.7 times more potent than lidocaine in weighted and 7 times more potent in molar ratios at analgesic EC50, in the volume of local anesthetic studied.