Oral Analgesic Requirements Research Articles

Percutaneous neuromodulation therapy; does the location of electrical stimulation effect the acute analgesic response? (University of Texas Southwestern Medical Center at Dallas, Dallas, TX) Anesth Analg 2000;91:949–954.

This article studied the effect of the location of electrical stimulation on the acute analgesic response to percutaneous neuromodulation therapy in patients with nonradiating neck pain. Sixty‐eight patients received 3 different nonpharmacologic modalities, namely “needles only (neck), local (neck) dermatomal stimulation, and remote (lower back) dermatomal stimulation in a random sequence over the course of an 11‐week study period. All treatments were given for 30 min, 3 times per week for 3 weeks with 1 week “off” between each modality. The assessment tools included the health status survey short form (SF‐36) questionnaire as well as 10‐cm visual analog scales for assessing pain, physical activity, and quality of sleep. The pain visual analog scale was repeated 5‐10 min after each treatment session. The daily oral nonopioid analgesic requirements were recorded in the patient diary during the entire study period. At the end of each 3‐week treatment block, the SF‐36 questionnaire was repeated. Compared with needles only and remote dermatomal stimulation, local dermatomal stimulation produced a significantly greater decrease in pain, increase in physical activity, and improvement in the quality of sleep compared with baseline values (P < 0.05). The posttreatment SF‐36 test results revealed that all 3 modalities produced improvements compared with the prestudy scores for both the physical component summary and mental component summary. However, the magnitude of the changes in the physical component summary and mental component summary with local dermatomal stimulation was significantly greater than needle only or remote dermatomal stimulation. No side effects were reported at the needle insertion sites. Conclude that electrical stimulation at the specific dermatomal levels corresponding to the local pathology produces greater short‐term improvements in pain control, physical activity, and quality of sleep in patients with chronic neck pain.Comment by Alan Kaye, M.D. Percutaneous neuromodulation is a therapy in which percutaneous electrical nerve stimulation is applied for short‐term relief of various pain syndromes. In this study involving 68 patients by White et al, the effects of neuromodulation therapy were studied with nonradiating neck pain. Local dermatomal stimulation consisted of placement of 10 32‐gauge stainless steel acupuncture needle probes to a depth of 2‐4 cm into the soft tissue and paraspinous muscles in the cervical region. For electrical therapy, 10 probes were connected to 5 bipolar leads from a low‐output electrical generator and stimulated for 30 min at 15 and 30 cycles/s. Finally, remote dermatomal electrical therapy consisted of placement of 10 32‐gauge stainless steel acupuncture‐like needle probes to a depth of 2‐4 cm into the soft tissue and/or paraspinous muscle in the lower back region. Each modality was administered to all patients 3 times per week for 3 consecutive weeks with 1 week off between each modality. Most parameters compared after demonstrated improvement locally and a reduction in daily usage of oral nonopioid analgesic medications. Future studies are warranted, in particular those in which long‐term benefits are assessed. The authors should be commended for studying this alternative treatment strategy and its role in mediating or modulating complex pain syndromes.

Percutaneous Electrical Nerve Stimulation—A Novel Analgesic Therapy For Diabetic Neuropathic Pain

OBJECTIVE—To evaluate the use of percutaneous electrical nerve stimulation (PENS) in the management of patients with painful diabetic peripheral neuropathy. RESEARCH DESIGN AND METHODS—A total of 50 adult patients with type 2 diabetes and peripheral neuropathic pain openface> 6 months duration involving the lower extremities were randomly assigned to receive active PENS (needles with electrical stimulation at an alternating frequency of 15 and 30 nz) and sham (needles only) treatments for 3 weeks. Each series of treatments was administered for 30 min three times a week according to a standardized protocol. After a 1‐week washout period, all patients were subsequently switched to the other modality. A 10‐cm visual analog scale (VAS) was used to assess pain, physical activity and quality of sleep before each session. The changes in VAS scores and daily requirements for oral analgesic medication were determined during each 3‐week treatment period. Patients completed the MOS 36‐Item Short‐Form Health Survey (SF‐36), the Beck Depression Inventory (BDI), and the Profile of Mood States (POMS) before and after completion of each treatment modality. At the end of the crossover study, a patient preference questionnaire was used to compare the effectiveness of the two modalities. RESULTS—Compared with the pain VAS scores before active (6.2 +/− 1.0) and sham (6.4 +/− 0.9) treatments, pain scores after treatment were reduced to 2.5 +/− 0.8 and 6.3 +/− 1.1, respectively. With active PENS treatment, the VAS activity and sleep scores were significantly improved from 5.2 +/− 1.0 and 5.8 +/− 1.3 to 7.9 +/− 1.0 and 8.3 +/− 0.7, respectively. The VAS scores for pain, activity, and sleep were unchanged from baseline values after the sham treatments. Patient's daily oral nonopioid analgesic requirements de‐creased by 49 and 14% after active and sham PENS treatments, respectively. The post‐treatment physical and mental components of the SF‐36, the BDI, and the POMS all showed a significantly greater improvement with active versus sham treatments. Active PENS treatment improved the neuropathic pain symptoms in all patients. CONCLUSIONS—PENS is a useful nonpharmacological therapeutic modality for treating diabetic neuropathic pain. In addition to decreasing extremity pain, PENS therapy improved physical activity, sense of well‐being, and quality of sleep while reducing the need for oral nonopioid analgesic medication.

Effect of the Duration of Electrical Stimulation on the Analgesic Response in Patients with Low Back Pain

Electrical stimulation of peripheral nerves produces acute analgesic effects. This randomized, sham-controlled, crossover study was designed to evaluate the effect of differing durations of electrical stimulation on the analgesic response to percutaneous electrical nerve stimulation in 75 consenting patients with low back pain. All patients received electrical stimulation for four different time intervals (0, 15, 30, and 45 min) in a random sequence over the course of an 11-week study period. All active percutaneous electrical nerve stimulation treatments were administered using alternating frequencies of 15 and 30 Hz three times per week for 2 consecutive weeks. The prestudy assessments included the health status survey short form questionnaire and 10-cm visual analog scale scores for pain, physical activity, and quality of sleep, with 0 being the best and 10 being the worst. The pain scoring was repeated 5-10 min after each 60-min study session and 24 h after the last treatment session with each of the four methods. The daily oral analgesic requirements were assessed during each of the four treatment blocks. At the end of each 2-week treatment block, the questionnaire was repeated. Electrical stimulation using percutaneously placed needles produced short-term improvements in the visual analog scale pain, physical activity, and quality of sleep scores, and a reduction in the oral analgesic requirements. The 30-min and 45-min durations of electrical stimulation produced similar hypoalgesic effects (48+/-21% and 46+/-19%, respectively) and were significantly more effective than either 15 min (21+/-17%) or 0 min (10+/-11%). The 30- and 45-min treatments were also more effective in improving physical activity and sleep scores over the course of the 2-week treatment period. In contrast to the sham treatment (0 min), the health status survey short form revealed that electrical stimulation for 15 to 45 min three times per week for 2 weeks improved patient function. The recommended duration of electrical stimulation with percutaneous electrical nerve stimulation therapy is 30 min.

Percutaneous electrical nerve stimulation: an alternative to TENS in the management of sciatica

Sciatica is a common pain problem and current pharmacologic therapies have proven inadequate for many patients. The objective of this sham-controlled investigation was to compare a novel non-pharmacologic technique, percutaneous electrical nerve stimulation (PENS), to transcutaneous electrical nerve stimulation (TENS) in the management of the radicular pain associated with sciatica. Sixty-four consenting patients with sciatica due to lumbar disc herniation were treated with PENS, TENS and sham-PENS according to a randomized, single-blinded, cross-over study. All patients had been maintained on a stable oral non-opioid analgesic regimen for at least 6 weeks prior to entering the study. Each treatment modality was administered for a period of 30 min three times per week for 3 weeks, with 1 week ‘off’ between each modality. Both PENS and TENS treatments were administered using a stimulation frequency of 4 Hz. The pre-treatment assessment included the health status survey short form (SF-36), as well as visual analog scales (VAS) for radicular pain, physical activity and quality of sleep. The pain VAS was also repeated after each treatment session. At the end of each 3-week treatment block, the SF-36 was repeated. After receiving all three treatment modalities, a global assessment questionnaire was completed. Both PENS (42%) and TENS (23%) were significantly more effective than the sham (8%) treatments in decreasing VAS pain scores. The daily oral analgesic requirements were also significantly reduced compared to the pre-treatment values with PENS ( P<0.01) and TENS ( P<0.05). However, PENS was significantly more effective than TENS (and sham-PENS) in improving physical activity and quality of sleep. The SF-36 evaluation confirmed the superiority of PENS (versus TENS and sham-PENS) with respect to post-treatment functionality. In the overall assessment, 73% of the patients reported that PENS was the most desirable modality (versus 21% for TENS and 6% for sham-PENS). Finally, 71% of the patients stated that they would be willing to pay extra to receive PENS therapy compared to 22% and 3% for TENS and sham-PENS, respectively. In this sham-controlled study, we concluded that PENS was more effective than TENS when administered at a stimulation frequency of 4 Hz in providing short-term pain relief and improved functionality in patients with sciatica.

Ropivacaine 0.25% and 0.5%, but not 0.125%, provide effective wound infiltration analgesia after outpatient hernia repair, but with sustained plasma drug levels

Background and Objectives. Ropivacaine is a long-acting local anesthetic similar to bupivacaine, but with lower cardiac toxicity and intrinsic vasoconstrictive properties that may reduce the risk and extent of systemic plasma absorption. Plasma levels and risks are associated with the total dose used and the extent of absorption, with lower doses potentially representing less risk. Although both 0.5% and 0.75% ropivacaine provide adequate analgesia for wound infiltration after hernia repair, the efficacy of lower doses and the early systemic absorption have not been reported. Methods. We studied postoperative pain and systemic plasma levels following either the injection of 30 mL of saline or 0.125%, 0.25%, or 0.5% ropivacaine into the wounds in 110 healthy patients following hernia repair under spinal anesthesia. Pain was assessed using visual analog scale (VAS) scores and algometer readings at rest and after coughing, and oral analgesic requirements were assessed in the first 5 hours after surgery and for the week after discharge. Results. Both 0.25% and 0.5% ropivacaine provided pain relief following surgery when compared with saline or 0.125%. No adverse reactions to the drug were reported in any group. Plasma levels of ropivacaine peaked between 30 and 60 minutes, at 0.109, 0.249, and 0.399 mg/L for 0.125%, 0.25%, and 0.5% concentrations, respectively. Although the levels were below those producing clinical symptoms, they remained elevated for the entire 2-hour sampling period. This implies an absorption-dependent elimination which is substantially longer than reported with other routes of injection. Conclusions. Ropivacaine 0.25% and 0.5% is adequate for pain relief after outpatient hernia repair, whereas the 0.125% solution is no more effective than saline. Prolonged systemic absorption from peripheral injection may be associated with prolonged elevations of plasma concentrations, which potentially could be associated with unexpectedly high plasma levels if repeated injections are performed in the perioperative period with higher concentrations or doses.

PERCUTANEOUS ELECTRICAL NERVE STIMULATION (PENS)

S209 INTRODUCTION: Sciatica due to a herniated nucleus pulposus is a common cause of pain and an important socioeconomic problem [1]. The lifetime prevalence of sciatica in the USA is 40% [2]. While both opioid and non-opioid analgesic medications may temporarily alleviate the symptoms of sciatica, both classes of drugs are associated with many well-known side effects. This randomized, cross-over, sham-controlled study was designed to compare the effectiveness of a novel non-pharmacologic therapy, percutaneous electrical nerve stimulation (PENS) [3], to transcutaneous electrical nerve stimulation (TENS) in the management of the radicular pain associated with sciatica. METHODS: Sixty-four consenting patients with radicular pain due to lumbar disc herniation were treated with three different therapeutic modalities (namely, PENS, sham-PENS and TENS) according to a randomized, cross-over study design. All patients had been maintained on a stable oral analgesic treatment regimen for at least 6 weeks prior to entering this IRB-approved study. The PENS (with electrical stimulation at frequency of 4 Hz) and sham-PENS (no electrical stimulation) treatments involved insertion of 10, 32-ga. acupuncture-like needle probes in a dermatomal pattern corresponding to the pain symptoms. [3] Each treatment was administered for a period of 30 min three times per week for 3 weeks in a random sequence with one week "off" between each treatment. The pre-treatment assessment included the health status survey short form (SF-36), as well as visual analog scales (VAS) for pain, physical activity and quality of sleep. The pain VAS was repeated 5-10 min after each treatment session. At the end of each 3-week treatment block, the SF-36 was also repeated. After the patient had received all three treatment modalities, a global assessment questionnaire was administered. RESULTS: PENS therapy was significantly more effective in decreasing VAS pain scores after each treatment than the sham-PENS (* p-value <0.05, psi p-value <0.01) and TENS ([club] p-value <0.05) therapies. The daily non-opioid oral analgesic requirements were decreased by 50% with PENS compared to only 29% and 8% with TENS and sham-PENS, respectively. In the overall assessment, 73% of the patients reported that PENS was the most effective pain-relieving modality. PENS was also significantly more effective in improving the patient's sense of "well-being" than the other two modalities. The SF-36 evaluations confirmed the superiority of PENS (versus sham-PENS and TENS) with respect to post-treatment functionality. Finally, 71% of the patients stated that they would be willing to pay "out of pocket" to receive PENS therapy compared to only 22% and 3% with TENS and sham-PENS, respectively. (Table 1)Table 1DISCUSSION: The pain and loss of mobility associated with sciatica greatly reduces a person's ability to function at home and at work [4]. This sham-controlled, cross-over study evaluating PENS therapy suggests that it is more effective in improving short-term outcome than conventional TENS in patients with sciatica. Future studies should be designed to examine the cost-effectiveness of these alternative therapies as supplements to conventional oral analgesics and exercise programs.

THE EFFECT OF INTRAOPERATIVE DEXAMETHASONE ON THE IMMEDIATE AND DELAYED POSTOPERATIVE MORBIDITY IN CHILDREN UNDERGOING AMBULATORY ADENOTONSILLECTOMY

S14 This prospective, double blind, placebo controlled study examined the effect of preoperative dexamethasone on post-operative nausea and vomiting (PONV) and 24 hr. recovery in 128 children undergoing ambulatory tonsillectomy. METHODS: With IRB approval and parental consent 128 children 2-12 yrs. of age, ASA physical status 1 and 2, participated. Each received oral midazolam 0.5-0.6 mg/kg (maximum dose 20 mg) preoperatively. Anesthesia was induced with halothane and nitrous oxide in 60% oxygen and was maintained with nitrous oxide and isoflurane. Intubation was facilitated by mivacurium 0.2 mg/kg. Each child received fentanyl 1[micro sign]g/kg IV before initiation of surgery. Dexamethasone 1 mg/kg, maximum dose 25 mg (steroid group) or placebo (saline group) was administered prior to initiation of surgery. Intraoperative fluids were standardized to 25-30 ml/kg of lactate Ringer's solution. RESULTS: Incidence of PONV, need for rescue antiemetic, quality of oral intake and analgesic requirements did not differ between the two groups prior to PACU discharge. However, during the 24 hour period following discharge from PACU, more patients in the saline group had PONV (62% vs 29%, respectively, p<0.05). Parental calls to the physician for complaints of pain, poor oral intake and/or PONV were also higher in the saline group. While none of the patients in the steroid group returned to hospital, 5 children in the saline group returned for management of PONV or IV hydration. Additionally, fewer children in the saline group had "good" to "excellent" oral intake compared to steroid group, (83% vs 58%, respectively, p<0.05) after home discharge. CONCLUSION: Preoperative administration of a single large dose of IV dexamethasone significantly decreased the overall incidence of PONV, [1,2] specifically during the 24 hours after home discharge in children undergoing ambulatory adenotonsillectomy. Preoperative dexamethasone also improved postoperative oral intake, reduced the number of phone calls from parents and prevented hospital returns for the management of PONV and poor oral intake during the 24 hours following home discharge. These benefits effects of dexamethasone, however, were not evident during early recovery. We propose that an antiemetic drug be added to minimize early PONV. However, further controlled studies are necessary to verify this proposal.

LOCALLY APPLIED TRANSDERMAL NITRATE PATCHES FOR THE TREATMENT OF ISCHAEMIC REST PAIN

SUMMARYPatients with severe peripheral vascular disease may suffer considerable pain which can be difficult to control with conventional analgesics. We sought to assess the analgesic effect of transdermal nitrate patches in such patients. A prospective trial was performed in 15 patients with ischaemic rest pain due to atherosclerotic peripheral vascular disease. Pain control and oral analgesic requirement were assessed. Fourteen of the 15 had a good or moderate response to the nitrate patches with a subsequent reduction in oral analgesic requirement. The patients with primarily small vessel disease had the greatest improvement in pain control. We conclude that topical nitrates may be used to provide rapid and safe analgesia for patients with ischaemic rest pain.

Analgesia after day-case knee arthroscopy: double-blind study of intra-articular tenoxicam, intra-articular bupivacaine and placebo

Arthroscopy of the knee is performed regularly on a day-case basis. Intra-articular bupivacaine produces transient analgesia and reports of analgesia using intra-articular morphine have produced conflicting results. Non-steroidal anti-inflammatory drugs given systemically can provide effective analgesia for this procedure. In this study we attempted to determine if intra-articular tenoxicam provided useful analgesia after day-case arthroscopy. Sixty three ASA I-II patients were allocated randomly to one of three groups to receive 40 ml of a solution containing 0.9% saline (group Pla), 0.25% bupivacaine (group Bup) or tenoxicam 20 mg (group Ten). The injection was made into the knee joint at the end of surgery, 10 min before tourniquet deflation. Verbal rating and visual analogue pain scores (at rest and on knee flexion), use of analgesia, mobilization and disturbance by pain at home were recorded for the next 48 h. There were no differences between pain scores in any of the three groups when tested at rest or on movement. Less analgesia was used in the first 24 h by patients in the tenoxicam group but the difference in time to first analgesia was not statistically significant. Side effects and disturbance by pain were similar in all groups. The use of intra-articular tenoxicam 20 mg at the end of arthroscopy reduced oral analgesic requirements during the first day after operation but did not alter patients' perception of pain.

Randomized trial of periportal peritoneal bupivacaine for pain relief after laparoscopic cholecystectomy

The aim of this study was to determine whether injection of a long-acting local anaesthetic, in relation to the port sites at the level of the parietal peritoneum, would reduce postoperative pain following laparoscopic cholecystectomy. Patients were entered into a randomized, prospective, double-blind study comparing the effects of a standard technique, in which bupivacaine (total of 20 ml, 0.5 per cent) was injected into the subcutaneous periportal tissue around the four port sites, and a technique in which bupivacaine (total of 20 ml, 0.25 per cent) was injected into the subcutaneous periportal tissue as above with the addition of periportal parietal peritoneal injection of bupivacaine (total of 20 ml, 0.25 per cent). Two scores for pain, with the patient at rest, and on movement, were assessed 6 and 18 h after surgery using a visual analogue pain scale. Median pain score was significantly higher in patients who received standard technique (n = 40) than in those given peritoneal injection (n = 40) at both 6 (rest = 3.0 versus 1.0, movement = 5.0 versus 2.9) and 18 h (rest = 1.9 versus 0, movement = 3.2 versus 1.2). Both opiate and oral analgesic requirements were reduced in patients administered peritoneal injection, although this was not statistically significant. The addition of periportal injection of bupivacaine at the level of the parietal peritoneum, performed under direct vision, reduces pain after laparoscopic cholecystectomy.

Post-herniorrhaphy pain in outpatients after preincision ilioinguinal-hypogastric nerve block during monitored anaesthesia care

The objective of this study was to evaluate the effect of an ilioinguinal-hypogastric nerve block (IHNB) with bupivacaine 0.25% on the postoperative analgesic requirement and recovery profile in outpatients undergoing inguinal herniorrhaphy with local anaesthetic infiltration. Thirty consenting healthy men undergoing elective unilateral inguinal herniorrhaphy procedures were randomly assigned to receive an IHNB with either saline or bupivacaine according to a double-blind, IRB-approved protocol. All patients received midazolam, 2 mg iv, and fentanyl 25 microgram iv, prior to injection of 30 ml of either bupivacaine 0.25% or saline through the oblique muscle approximately 1.5 cm medial to the anterior superior iliac spine. Subsequently, the surgeon infiltrated the incision site with a lidocaine 1% solution. Sedation was maintained during the operation with a variable-rate propofol infusion, 25-140 micrograms.kg-1.min-1. No significant differences were noted in the intraoperative doses of lidocaine, propofol and fentanyl in the two treatment groups. However, the pain visual analogue score at 30 min after entering the PACU was lower in the bupivacaine (versus saline) group (P < 0.05). Although the times to ambulation (86 +/- 18 vs 99 +/- 27 min) and being judged "fit for discharge" (112 +/- 49 vs 126 +/- 30 min) were similar in the two groups, the bupivacaine-treated (vs saline) patients required less oral analgesic medication after discharge (46% vs 85%). We concluded that the use of an ilioinguinal-hypogastric nerve block with bupivacaine 0.25% as an adjuvant during inguinal herniorrhaphy under monitored anaesthesia care decreased pain in the PACU and oral analgesic requirements after discharge from the day-surgery unit.

EXTRADURAL MORPHINE AND PAIN RELIEF FOLLOWING EPISIOTOMY

One hundred and fifty obstetric patients, who had received intrapartum extradural analgesia with bupivacaine, and had required episiotomy, were given a final postpartum injection of preservative-free morphine in saline, or saline alone, on a double-blind basis. The degree of perineal analgesia was assessed by linear analogue scale at intervals up to 36 h, and oral analgesic requirements were recorded. A significant degree of analgesia was obtained for up to 12 h with morphine 2 mg, compared with saline. Increasing the dose to 4 mg increased the occurrence of side-effects, and was associated with less marked analgesia.