Efficacy and safety of patient-controlled opioid analgesia for acute postoperative pain. A quantitative systematic review

Recent developments in patient-controlled analgesia

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

A placebo-controlled randomized clinical trial of perioperative administration of gabapentin, rofecoxib and their combination for spontaneous and movement-evoked pain after abdominal hysterectomy

Current treatments for post-injury movement-evoked pain are inadequate. Non-opioids may complement opioids, which preferentially reduce spontaneous pain, but most have incomplete efficacy as single agents. This trial evaluates efficacy of a gabapentin-rofecoxib combination following hysterectomy. In addition to IV-PCA morphine, 110 patients received either placebo, gabapentin (1800 mg/day), rofecoxib (50 mg/day) or a gabapentin-rofecoxib combination (1800/50 mg/day) starting 1 h pre-operatively for 72 h. Outcomes included pain at rest, evoked by sitting, peak expiration and cough, morphine consumption and peak expiratory flow (PEF). For placebo, gabapentin, rofecoxib and combination, 24 h pain (100 mm VAS) was: at rest-23.6 (P<0.05 vs. all treatments), 13.8, 14.4 and 12.1; during cough-50.7 (P<0.05 vs. all treatments), 41.5, 44.8 and 30.8; 48 h morphine consumption (mg) was: 130.4 (P<0.05 vs. all treatments), 81.7, 75.6 and 57.2 (P<0.05 vs. gabapentin and rofecoxib) and 48 h PEF (% baseline) was: 63.9 (P<0.05 vs. all treatments), 77.2, 76.7 and 87.5 (P<0.05 vs. gabapentin and rofecoxib). Adverse effects were similar in all groups except sedation which was more frequent with gabapentin. Combination and rofecoxib reduced pain interference with movement, mood and sleep (P<0.05) and combination was superior to gabapentin for all these three (P<0.05). These data suggest that a gabapentin-rofecoxib combination is superior to either single agent for postoperative pain. Other benefits include opioid sparing, reduced interference with movement, mood and sleep and increased PEF suggesting accelerated pulmonary recovery. Future research should identify optimal dose-ratios for this and other analgesic combinations.

Effects of acetaminophen on morphine side-effects and consumption after major surgery: meta-analysis of randomized controlled trials † †Presented in part at the Annual Meeting of the Société Française d’Anesthésie-Réanimation, Paris, April 2004

BACKGROUND

Acetaminophen is commonly used for the management of perioperative pain. However, there is a marked discrepancy between the extent to which acetaminophen is used and the available evidence for an analgesic effect after major surgery. The aim of this systematic review is to determine the morphine-sparing effect of acetaminophen combined with patient-controlled analgesia (PCA) with morphine and to evaluate its effects on opioid-related adverse effects.

METHODS

MEDLINE and the Cochrane Library were searched to select randomized controlled trials which compared PCA morphine alone with PCA morphine plus acetaminophen administered orally or intravenously. Studies were evaluated for their quality based on the Oxford Quality Scale. Outcome measures were morphine consumption over the first 24 h after surgery, patient satisfaction and the incidence of morphine side-effects, including nausea and vomiting, sedation, urinary retention, pruritus and/or respiratory depression.

RESULTS

Seven prospective randomized controlled trials, including 265 patients in the group with PCA morphine plus acetaminophen and 226 patients in the group with PCA morphine alone, were selected. Acetaminophen administration was not associated with a decrease in the incidence of morphine-related adverse effects or an increase in patient satisfaction. Adding acetaminophen to PCA was associated with a morphine-sparing effect of 20% (mean, -9 mg; CI -15 to -3 mg; P=0.003) over the first postoperative 24 h.

CONCLUSION

Acetaminophen combined with PCA morphine induced a significant morphine-sparing effect but did not change the incidence of morphine-related adverse effects in the postoperative period.

Multimodal Analgesia Techniques and Postoperative Rehabilitation

The concept of multimodal analgesia involves the use of different classes of analgesics and different sites of analgesic administration to provide superior dynamic pain relief with reduced analgesic-related side effects. Although multimodal analgesia techniques have assumed increasing importance in the management of perioperative pain, it has become increasingly apparent that postoperative outcome may not be improved. Nevertheless, the integration of multimodal analgesia techniques with a multimodal and multidisciplinary rehabilitation program may enhance recovery, reduce hospital stay, and facilitate early convalescence.

Patient controlled intravenous opioid analgesia versus continuous epidural analgesia for pain after intra-abdominal surgery

BACKGROUND

There are two common techniques for postoperative pain control after intra-abdominal surgery: patient-controlled analgesia (PCA) with intravenous opioids and continuous epidural analgesia (CEA). It is uncertain which method has better pain control and fewer adverse effects.

OBJECTIVES

The objective of this review was to compare PCA opioid therapy with CEA for pain control after intra-abdominal surgery in terms of analgesic efficacy, side effects, patient satisfaction and surgical outcome by meta-analysis of the relevant trials.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library Issue 4, 2002), MEDLINE (January 1966 to October 2002), EMBASE (January 1988 to October 2002), and reference lists of articles. We also contacted researchers in the field.

SELECTION CRITERIA

Randomized controlled trials of adult patients after intra-abdominal surgery comparing the effect of two pain control regimens in terms of analgesic efficacy and side effects. In the patient-controlled analgesia (PCA) group the patient should be able to operate the device himself. In the continuous epidural analgesia group there was no PCA device.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. Adverse effects information was collected from the trials.

MAIN RESULTS

Nine studies involving 711 participants were included. The PCA group had a higher pain visual analogue scale than the CEA group during 6, 24 and 72 hour periods. The weighted mean difference and 95% confidence interval of resting pain was 1.74 (95% CI 1.30 to 2.19), 0.99 (95% CI 0.65 to 1.33), and 0.63 (95% CI 0.24 to 1.01), respectively. The length of hospital stay and other adverse effects were not statistically different except that the incidence of pruritus was lower in the PCA group, odds ratio of 0.27 (95% CI 0.11 to 0.64).

AUTHORS' CONCLUSIONS

CEA is superior to opioid PCA in relieving postoperative pain for up to 72 hours in patients undergoing intra-abdominal surgery, but it is associated with a higher incidence of pruritus. There is insufficient evidence to draw comparisons about the other advantages and disadvantages of these two methods of pain relief.

Prevention and treatment of postoperative pain with particular reference to children

Pain therapy is an important aspect of medical practice for patients of all ages, to optimize care, to obtain an adequate quality of life and to improve their general conditions. Pain is among the most prevalent symptoms experienced by patients undergoing surgery. The success of postoperative pain therapy depends on the ability of the clinician to assess the presenting problems, identify and evaluate pain syndromes and formulate a plan for comprehensive continuing care. The prevalence of acute pain has led to the need to develop techniques for the assessment and management of this symptom in order to focus the attention on an interdisciplinary therapeutic approach (including pharmacologic, cognitive-behavioral, psychologic and physical treatment) and on the timing of different interventions (pre and postoperative). In this chapter we describe the principal therapeutic approaches to control pain in post-operative patients, such as non-opioid, opioid and adjuvant analgesics with particular attention in paediatric age. Moreover we report the principal scales to assess the pain intensity in the post-operative period. The need of a multidisciplinatory team and of a pre and postoperative pain management program represents an important goal in order to obtain effective pain relief and optimize pediatric care and rapid recovery. The introduction of a perioperative team service will improve the approach to pain management programs and it is considered the most important challenge for future.

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

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

Strategies for postoperative pain management

Despite advances in our understanding of the neurobiology of nociception, postoperative pain continues to be undertreated. There are many modalities that may provide effective postoperative analgesia, including systemic (e.g. opioids, non-steroidal anti-inflammatory agents) and regional analgesic options. The particular modality or modalities utilized for a particular patient will depend on the risk-benefit profile and patient preferences. Ideally, analgesic options should be incorporated into a multimodal approach to facilitate patient recovery after surgery.

Evaluation of Postoperative Pain Control for Women Undergoing Surgery for Gynaecologic Malignancies

OBJECTIVES

(1) To compare the benefits of epidural analgesia and patient-controlled analgesia (PCA) in the management of postoperative pain in women with gynaecologic malignancies,and (2) to understand issues related to the delivery of pain control strategies.

METHODS

A retrospective cohort study, based on chart review, was conducted of all women with gynaecologic malignancies who received either PCA or epidural analgesia at the Henderson Division of Hamilton Health Sciences, Hamilton, Ontario, from May 20, 1999, to July 17, 2001. Both objective (i.e., daily pain scores) and subjective (i.e., nursing progress notes) concerns were captured in the data collection instrument.

RESULTS

Ninety-seven women had PCA and 122 had epidural analgesia as their primary form of postoperative analgesia. Pain scores were excellent (<2, range 0-10) in both groups. The nausea score was superior for the epidural group. Twenty percent of women experienced motor blocks and 17% had sensory blocks, which impeded their ability to walk for the first 3 days after surgery. Pruritus, rash, and Benadryl use were seen in more than 20% of the epidural group. Prolonged catheterization and a 3-fold increased risk of urinary tract infections were seen in the epidural group. Epidural catheter leaks occurred in 12.3% of the women on epidural analgesia.

CONCLUSIONS

Postoperative pain management was excellent both in women who received PCA and in those who received epidural analgesia. Problems related to the delivery of pain control were more common in the epidural group.

Strategies for postoperative nausea and vomiting

Significant improvement towards a better control of postoperative nausea and vomiting have been achieved in recent years. Today, we understand better who is likely to vomit or to be nauseous after surgery. Significant amounts of the huge literature on anti-emetic interventions have been systematically reviewed, critically appraised and quantitatively synthesized. Thus, we know what anti-emetic interventions work, and how well they work, and we know their adverse effect profile. We also know which interventions have no worthwhile efficacy. A rational approach to postoperative nausea and vomiting includes three steps: identification of patients at risk, keeping the baseline risk low, and prophylactic administration of anti-emetics in those patients who are most likely to need them. For patients who are identified as high-risk patients, all measurements should be simultaneously initiated (multimodal anti-emesis).

Regional anesthesia and perioperative outcome: what is new?

PURPOSE OF REVIEW

This review of the most recent publications is aimed to look at the current developments regarding the effects of regional anesthesia on perioperative outcome.

RECENT FINDINGS

The debate continues on whether regional anesthesia and analgesia improve outcome or not. Researchers are still divided in their views. While previous meta-analyses are more favorable, more recent trials are rather on the con side. In an attempt to lessen heterogeneity, meta-analyses have now incorporated data from more recent trials to perform subgroup analyses. Such analyses persistently show the same positive results. The established outcome effects of regional anesthesia are mostly due its ability to provide superior analgesia, its ability to reduce the perioperative stress response and subsequent physiologic perturbations, and its ability to reduce pulmonary complications. Its potential to prevent cardiac morbidity in patients undergoing coronary artery bypass grafting is investigated further by looking at valuable specific biological markers like troponin I and natriuretic peptides. Intrathecal opioids do not seem to improve outcome, unlike the intrathecal local anesthetics. The latter improve outcome presumably by blocking the surgical stress response. In contrast, opioids, non-steroidal antiinflammatory drugs and cyclooxygenase-2 inhibitors have been shown not to impact outcome presumably by not being able to interfere with the stress response. The safety and efficacy of epidural or spinal anesthesia for spinal surgery continue to be demonstrated by current studies.

SUMMARY

Despite the controversies, the numerous potential benefits and advantages of regional anesthesia are keys to its continued popularity. With constant search for new scientific clues by improving experimental designs, valuable evidence slowly unfolds. Regional anesthesia certainly takes a leading role in the current trends for a multimodal approach of perioperative pain management.

A background infusion of morphine enhances patient-controlled analgesia after cardiac surgery

PURPOSE

We compared the efficacy of patient-controlled analgesia (PCA), with or without a background infusion of morphine, on postoperative pain relief in patients extubated in the operating room after coronary artery bypass grafting (CABG) surgery.

METHODS

With Faculty Ethics approval, 60 consenting adults undergoing elective coronary artery surgery were randomly assigned to receive either morphine PCA alone (group PCA-A, n = 30) or morphine PCA plus a background infusion (group PCA-B, n = 30) for 24 hr postoperatively. Pain scores with verbal rating scale (VRS; from 0 to 10) at rest, sedation scores, morphine consumption and delivery/demand ratios were assessed at zero, one, two, four, six, 12 and 24 hr after surgery. Hemodynamic variables and arterial blood gases were also recorded in the same periods.

RESULTS

Sedation scores in the two groups were similar. At all study periods after the first postoperative hour, VRS remained below 5 in both groups. Pain scores were significantly lower in the background infusion group, which also had greater cumulative morphine consumption (61.7 +/- 10.9 mg vs 38.5 +/- 16.2 mg). There were no episodes of hypoxemia or hypertension.

CONCLUSION

Morphine PCA effectively controlled postoperative pain after cardiac surgery. The addition of a background infusion of morphine enhanced analgesia and increased morphine consumption.

Anaesthesia, surgery, and challenges in postoperative recovery

Surgical injury can be followed by pain, nausea, vomiting and ileus, stress-induced catabolism, impaired pulmonary function, increased cardiac demands, and risk of thromboembolism. These problems can lead to complications, need for treatment in hospital, postoperative fatigue, and delayed convalescence. Development of safe and short-acting anaesthetics, improved pain relief by early intervention with multimodal analgesia, and stress reduction by regional anaesthetic techniques, beta-blockade, or glucocorticoids have provided important possibilities for enhanced recovery. When these techniques are combined with a change in perioperative care a pronounced enhancement of recovery and decrease in hospital stay can be achieved, even in major operations. The anaesthetist has an important role in facilitating early postoperative recovery by provision of minimally-invasive anaesthesia and pain relief, and by collaborating with surgeons, surgical nurses, and physiotherapists to reduce risk and pain.

The antiemetic efficacy of droperidol added to morphine patient-controlled analgesia: a randomized, controlled, multicenter dose-finding study

The antiemetic dose response of droperidol when it is added to patient-controlled analgesia with morphine is not well known. We randomly allocated adults who received postoperative morphine patient-controlled analgesia (1-mg bolus, 5-min lockout) to one of four regimens: no droperidol (control) or 5, 15, or 50 micro g of droperidol per milligram of morphine. Efficacy and adverse effects were recorded during 24 h and were analyzed with number needed to treat (NNT) and number needed to harm with 95% confidence intervals. Data from 82 controls, 82 patients receiving droperidol 5 micro g, 82 receiving droperidol 15 micro g, and 83 receiving droperidol 50 micro g were analyzed. Average consumption of droperidol per 24 h was 0.2 mg with the 5- micro g regimen, 0.61 mg with the 15- micro g regimen, and 2.04 mg with the 50- micro g regimen. In controls, the incidence of nausea was 48.8%; with droperidol 5 micro g, it was 42.7% (NNT compared with control, 16 [95% confidence interval, 4.7 to -11]); with 15 micro g, it was 32.9% (NNT, 6.3 [3.3-100]); and with 50 micro g, it was 21.7% (NNT, 3.7 [2.4 to 7.6]). In controls, the incidence of vomiting was 24.4%; with droperidol 5 micro g, it was 23.2% (NNT compared with control, 82 [7 to -8.5]); with 15 micro g, it was 22.0% (NNT, 41 [6.5 to -9.6]); and with 50 micro g, it was 12% (NNT, 8.1 [4.2-142]). In controls, the incidence of pruritus was 12.2%; with droperidol 5 micro g, it was 6.1% (NNT compared with control, 16 [6.7 to -37]); and with 15 and 50 micro g, it was 2.4% (NNT, 10 [5.7-52]). In controls, the incidence of sedation was 2.4%; with droperidol 5 micro g, it was 8.5% (number needed to harm (NNH) compared with control, 16 [7.7 to -123]); with 15 micro g, it was 6.1% (NNH, 27 [10 to -40]); and with 50 micro g, it was 18.1% (NNH, 6.4 [4.1-15]). There were no extrapyramidal symptoms and no cardiac adverse events. There was no difference in patient satisfaction. The optimal antiemetic dose of droperidol is 15-50 micro g/mg of morphine. Larger doses may have more antivomiting efficacy but are likely to be unacceptably sedating.

Continuous spinal anesthesia/analgesia vs. single-shot spinal anesthesia with patient-controlled analgesia for elective hip arthroplasty

BACKGROUND

In total hip replacement surgery several anesthesiological techniques can be used. In this study we compared continuous spinal anesthesia (CSA) and postoperative analgesia vs. single-shot spinal anesthesia (SPA) and postoperative patient-controlled intravenous analgesia with morphine (SPA).

METHODS

In a prospective randomized study, 68 patients, ASA I-III, between 50 and 85 years of age were allocated to these two groups. Quality of analgesia, hemodynamic stability and technical difficulties, as well as incidence of postoperative nausea and vomiting (PONV) and post dural puncture headache (PDPH), were recorded during a 24-h period.

RESULTS

Visual analog scale (VAS) scores were significantly lower in the CSA group from 3 h post operation (P < 0.05). Mean arterial pressure dropped by 21 +/- 11 mmHg in the CSA group and 29 +/- 14 in the SPA group during induction (P < 0.05). Technical difficulties and incidence of PDPH were similar in both groups. Postoperative nausea and vomiting was lower in the CSA group (P < 0.05).

CONCLUSIONS

Continuous spinal anesthesia/analgesia is a very practicable method providing better postoperative analgesia and better hemodynamic stability during anesthesia induction than SPA followed by morphine PCA analgesia after total hip replacement surgery.

Effects of adjunctive Swedish massage and vibration therapy on short-term postoperative outcomes: a randomized, controlled trial

OBJECTIVE

To examine the effects of adjunctive postoperative massage and vibration therapy on short-term postsurgical pain, negative affect, and physiologic stress reactivity.

DESIGN

Prospective, randomized controlled trial. The treatment groups were: (1) usual postoperative care (UC); (2) UC plus massage therapy; or (3) UC plus vibration therapy.

SETTING

The University of Virginia Hospital Surgical Units, Gynecology-Oncology Clinic, and General Clinical Research Center.

SUBJECTS

One hundred and five (N = 105) women who underwent an abdominal laparotomy for removal of suspected cancerous lesions.

INTERVENTIONS

All patients received UC with analgesic medication. Additionally, the massage group received standardized 45-minute sessions of gentle Swedish massage on the 3 consecutive evenings after surgery and the vibration group received 20-minute sessions of inaudible vibration therapy (physiotones) on the 3 consecutive evenings after surgery, as well as additional sessions as desired.

OUTCOME MEASURES

Sensory pain, affective pain, anxiety, distress, analgesic use, systolic blood pressure, 24-hour urine free cortisol, number of postoperative complications, and days of hospitalization.

RESULTS

On the day of surgery, massage was more effective than UC for affective (p = 0.0244) and sensory pain (p = 0.0428), and better than vibration for affective pain (p = 0.0015). On postoperative day 2, massage was more effective than UC for distress (p = 0.0085), and better than vibration for sensory pain (p = 0.0085). Vibration was also more effective than UC for sensory pain (p = 0.0090) and distress (p = .0090). However, after controlling for multiple comparisons and multiple outcomes, no significant differences were found.

CONCLUSIONS

Gentle Swedish massage applied postoperatively may have minor effects on short-term sensory pain, affective pain, and distress among women undergoing an abdominal laparotomy for removal of suspected malignant tissues.

Quantitative determination of piritramide in human serum applying liquid chromatography-two-stage mass spectrometry

A method for the determination of the synthetic narcotic analgesic piritramide in human serum utilizing high-performance liquid chromatography with atmospheric pressure chemical ionization two-stage mass spectrometry (HPLC-APCI-MS-MS) is presented. Pipamperone is used as the internal standard. Serum samples are prepared by liquid-liquid extraction under basic conditions with 1-chlorobutane. The chromatographic separation is achieved on an RP-18 stationary phase applying gradient elution with methanol-0.02% trifluoroacetic acid in water. Detection is carried out in the MS-MS single reaction monitoring mode of the ion-trap mass spectrometer. The limit of detection is 0.3 ng/ml and the calibration covers the range of 1-80 ng/ml. The intra-day RSDs are 6.1 to 7.3% over the calibration range, whereas the inter-day RSDs are 9.6 to 12.8%.

How to implement an acute pain service

To implement a successful acute pain service the following factors are the most important for success: anaesthesiologist-supervised pain nurses and an ongoing educational programme for patients and all health personnel involved in the care of surgical patients. The benefits in increased patient satisfaction and improved outcome after surgery will far outweigh the costs of running an acute pain service that raises standards of pain management throughout the hospital. Optimal use of basic pharmacological analgesia will improve relief of post-operative pain for most surgical patients. More advanced approaches, such as well-tailored epidural analgesia, are needed to relieve severe dynamic pain (e.g. when coughing). This may reduce markedly risks of complications in patients at high risk of developing post-operative respiratory infections and cardiac ischaemic events. More aggressive methods for post-operative pain management need robust routines that will discover the early symptoms and signs of potentially serious complications. High preparedness must be present for swift and correct handling of the rare but potentially catastrophic complications of bleeding and infection in the spinal canal. Chronic pain is common after surgery. Better acute pain relief may reduce this distressing long-term complication of surgery. Research into the long-term effects of optimal neuraxial analgesia and drugs that dampen glutamatergic hyperphenomena (hyperalgesia/allodynia) are urgently needed to verify whether these approaches can reduce the problem of intractable chronic post-operative pain.

Interscalene brachial plexus block is superior to subacromial bursa block after arthroscopic shoulder surgery

BACKGROUND

Arthroscopic shoulder surgery is often associated with severe postoperative pain. The results concerning subacromial bursa blockade (SUB) as a method of pain relief have been contradictory. We hypothesized that a SUB and interscalene brachial plexus block (ISB) would similarly reduce early postoperative pain and the need for oxycodone as compared to placebo (PLA).

METHODS

Forty-five patients scheduled for arthroscopic shoulder surgery were enrolled in this randomised, prospective study. The ISB and SUB blockades were performed with 15 ml of ropivacaine (5 mg/ml). In the PLA group, 15 ml of 0.9% saline was injected into the subacromial bursa. All patients received general anaesthesia.

RESULTS

The mean intravenously patient-controlled delivered oxycodone consumption during the first 6 h was significantly lower in the ISB group (6 mg) than in the SUB group (24.1 mg; P=0.001) or in the PLA group (27 mg; P<0.001). No significant differences were detected between the SUB and PLA groups (P=0.791). The postoperative pain scores during the first 4 h at rest and during the first 6 h on movement were significantly lower in the ISB group than in the SUB and PLA groups.

CONCLUSION

After arthroscopic shoulder surgery SUB has a minor effect only on postoperative analgesia, whereas an ISB with low-dose ropivacaine effectively relieves early postoperative pain and reduces the need for opioids.