Continuous Extradural Infusion Research Articles

Postoperative hypoxaemia: continuous extradural infusion of bupivacaine and morphine vs patient-controlled analgesia with intravenous morphine

We carried out a randomized prospective study in 60 patients who had undergone major abdominal surgery for cancer. For postoperative pain control, 30 patients received continuous extradural infusion of 0.125% bupivacaine 12.5 mg h-1 and morphine 0.25 mg h-1 (EXI group) and 30 received patient-controlled analgesia (PCA) with intravenous morphine (1 mg bolus, 5-min lock-out and maximum dose 20 mg 4h-1). Both groups had general anaesthesia. The two groups were compared for postoperative pain scores, satisfaction, sedation and oxygen saturation. Oxygen saturation was recorded continuously the night before surgery and for two consecutive postoperative nights. Episodes of moderate desaturation (90% > SpO2 85%) were more frequent in the EXI group than in the PCA group (P < 0.05). Pain scores were lower in the EXI group compared with the PCA group at rest and while coughing (P < 0.05). No significant difference was found for patient sedation and satisfaction.

Postoperative Analgesia by Continuous Extradural Infusion of Ropivacaine After Upper Abdominal Surgery

Comment: The authors adopted a different approach to traditional dose-response studies. Instead of using one concentration of ropivacaine and varying the infusion rate, they used differing concentrations of ropivacaine at the fixed rate of 10 mL/hr. With these methods, the authors demonstrated superior analgesia as measured by a visual analog scale for pain at rest and on coughing with the 0.2 and the 0.3% concentrations. The 0.3% concentration had the lowest intravenous morphine requirement during the study period. One of ten patients in each of the 0.2 and 0.3% groups developed motor block, whereas no motor block occurred in the control or 0.1% infusion groups. The 0.2 and the 0.3% concentrations were also associated with a higher incidence of hypotension that was easily treated with an increase in the intravenous infusion rate. Thus, the 0.3% concentration seems to be the best epidural solution for the immediate 24-hr postoperative period in terms of achieving analgesia after major upper abdominal surgery without the addition of neuraxial opioids. One major risk following abdominal surgery is pulmonary infection.1 Coughing and deep breathing are important to prevent both atelectasis and infection. The benefit of decreased pain with coughing outweighs the small risk of minor hypotension. Furthermore, patients will not be ambulating during the first 24-hr period. It would be interesting to extend this study beyond the 24-hr period to determine whether there would be any benefit to then switching to the lower concentrations.

Continuous Extradural Infusion of Ropivacaine for Prevention of Postoperative Pain After Major Orthopaedic Surgery

Comment: These authors investigated various infusion rates of 0.2% ropivacaine for postoperative analgesia after orthopedic surgery. Typically, the infusion mixture is a combination of opioid and local anesthetic to allow low doses of each to prevent side effects and minimize motor block. However, some patients do not tolerate neuraxial opioids and would benefit from the results of this study. Ropivacaine is a new amide local anesthetic, which is similar in structure to bupivacaine or mepivacaine. Unlike these two local anesthetics, ropivacaine is prepared as the pure s-enantiomer. It has less central nervous system and cardiovascular toxicity compared with bupivacaine1 and possibly less motor blockade.2 As such, it possesses several advantages as a postoperative epidural analgesia. The authors studied five infusion rates (6, 8, 10, 12, and 14 cc/hr) and constructed a dose-response curve for postoperative epidural infusion. As expected, the higher infusion rates provided better analgesia as measured by visual analog pain scores and postoperative morphine requirements. However, as the infusion rates increased, so did the incidence of side effects such as hypotension and urinary retention. The optimal infusion rate was 10 mL/hr, which provided the best analgesia with the least degree of side effects. Another point in this study deserves mention. The protocol was designed so that all patients had epidural anesthesia before surgery. The control group received a postoperative infusion of saline. The mean total morphine requirement for a 21-hr period in this group was 36 mg, a surprisingly low number. Even if patients do not receive a postoperative epidural infusion, this fact argues for its use intraoperatively to provide preemptive analgesia.

Continuous extradural infusion of ropivacaine 2 mg ml-1 for pain relief during labour

We have assessed the dose-response relationship of a solution of ropivacaine 2 mg ml-1, given as a continuous extradural infusion to women in labour. A total of 133 parturients were allocated randomly to one of four groups to receive a fixed rate ropivacaine infusion of 4, 6, 8 or 10 ml h-1 with additional bolus doses as necessary. Contraction pain, quality of analgesia, sensory block, motor block and neonatal Apgar scores were assessed. There were no significant differences between groups in terms of analgesia or motor block, although significantly more bolus doses were required by the group receiving 4 ml h-1 (P < 0.05 compared with the other groups), and a significantly higher total dose of ropivacaine was administered to the 10-ml h-1 group compared with the 6-ml h-1 group (P = 0.044). There were no significant differences between groups in terms of obstetric or neonatal outcome. We conclude that ropivacaine 2 mg ml-1 was effective and well tolerated when given as a continuous extradural infusion at 6-8 ml h-1 and may be used as the sole analgesic during labour.

A.331 Randomized comparison of continuous extradural Infusion with either 0.125% bupivacaine or 0.0625% bupivacaine + 0.25 µg ml−1 sufentanil during labour with breech presentation

A.331 Randomized comparison of continuous extradural Infusion with either 0.125% bupivacaine or 0.0625% bupivacaine + 0.25 µg ml−1 sufentanil during labour with breech presentation

Continuous extradural infusion of ropivacaine for prevention of postoperative pain after major orthopaedic surgery

We studied 151 patients undergoing total hip or knee arthroplasty, or cruciate ligament reconstruction in a multicentre study in Australia and New Zealand. Patients were openly allocated randomly to one of five treatment groups or to a control group. General anaesthesia was induced after introduction of extradural block with 0.5% ropivacaine. After surgery, patients received an extradural infusion of 0.2% ropivacaine at 6, 8, 10, 12 or 14 ml h-1 or received no postoperative extradural infusion (control group). All patients had access to i.v. PCA morphine for supplementary analgesia. Morphine consumption was lower in all treatment groups compared with the control group, decreasing with increasing ropivacaine infusion rate. Median VAS scores were lower in all ropivacaine infusion groups compared with the control group for the first 10 h of the study; however by the end of the study, VAS scores were similar in all groups. The higher ropivacaine infusion rates caused a slower convergence of spread of the initial sensory block and a higher degree of motor block. The overall incidence of side effects was similar, with the exception of a higher incidence of urinary retention and hypotension in the groups receiving the higher rates of ropivacaine. The quality of treatment scores were similar for all treatment groups (Br. J. Anaesth. 1996; 76: 606-610).

Postoperative analgesia by continuous extradural infusion of ropivacaine after upper abdominal surgery

Ropivacaine is a new local anaesthetic with advantages that suggest an important role in the provision of postoperative analgesia. The main aim of this study was to investigate the dose-response relationship of extradural infusion of ropivacaine. We studied 36 ASA I-III patients undergoing upper abdominal surgery during general anaesthesia and extradural block (catheter insertion at T6-9) using 0.5% ropivacaine in a randomized, double-blind study. After surgery nine patients each received an extradural infusion of either ropivacaine 0.1%, 0.2%, 0.3% or saline at a rate of 10 ml h-1 for 21 h. All patients had access to i.v. morphine via a PCA device. The ropivacaine groups consumed significantly less morphine over the 21-h infusion period than the saline group (medians: saline 75 mg; 0.1% ropivacaine 32 mg; 0.2% ropivacaine 39 mg; 0.3% ropivacaine 13 mg) (P < 0.05). Pain (VAS scores) at rest was significantly lower in all ropivacaine groups than in the saline group after 4 h of infusion (medians: saline 45 mm; 0.1% ropivacaine 15 mm; 0.2% ropivacaine 12 mm; 0.3% ropivacaine 0 mm). Pain on coughing was significantly less in all ropivacaine groups than in the saline group after 4 h infusion (medians: saline 67 mm; 0.1% ropivacaine 44 mm; 0.2% ropivacaine 33 mm; 0.3% ropivacaine 0 mm) and for 0.2% and 0.3% ropivacaine at later times. Motor block was negligible throughout the infusion. Patient satisfaction was higher in the 0.2% and 0.3% ropivacaine groups than in the two other groups.

Postoperative extradural analgesia in children: comparison of morphine with fentanyl

We have compared the efficacy and side effects of extradural morphine with extradural fentanyl for postoperative pain relief. Thirty children (ages 1-16 yr) were allocated randomly to receive, after extradural administration of 0.5% bupivacaine 0.75 ml kg-1 and before surgical incision, extradural morphine 0.75 microgram kg-1 (group M), with an additional dose administered 24 h later or extradural fentanyl 2 micrograms kg-1 (group F) followed by a continuous extradural infusion (during 48 h). There was no major complication (respiratory depression). Pain scores were satisfactory in both groups for 48 h. Ventilatory frequency was greater in group M 20, 21, 22, 23 and 25 h after the beginning of analgesia (P < 0.05). Pruritus, nausea and vomiting were less common with extradural fentanyl (20% vs 53%, P < 0.05 and 0% vs 33%, P < 0.05) than with morphine. Urinary retention occurred with equal frequency (25%) in the two groups. After a bolus of 2 micrograms kg-1, continuous extradural infusion of fentanyl 5 micrograms kg-1 day-1 provided analgesia comparable to that from a daily bolus of extradural morphine 0.75 mg kg-1 and produced fewer side effects.

INFLUENCE OF TIMING ON THE EFFECT OF CONTINUOUS EXTRADURAL ANALGESIA WITH BUPIVACAINE AND MORPHINE AFTER MAJOR ABDOMINAL SURGERY

We have studied the effect of continuous extradural analgesia with bupivacaine and morphine, initiated before or after colonic surgery, in a double-blind, randomized study. Thirty-two patients were allocated randomly to receive an identical extradural block initiated 40 min before surgical incision (n = 16) or at closure of the surgical wound (n = 16). The extradural regimen consisted of a bolus of 7 ml of plain bupivacaine 7.5 mg ml-1 plus morphine 2 mg and continuous extradural infusion of a mixture of bupivacaine 7.5 mg ml-1 plus morphine 0.05 mg ml-1, 4 ml h-1 for 2 h, followed by a continuous extradural infusion of a mixture of bupivacaine 2.5 mg ml-1 plus morphine 0.05 mg ml-1, 4 ml h-1, continued for 72 h after operation. In addition, all patients received similar general anaesthesia. There was no significant difference in request for additional morphine and no significant differences between the groups in pain scores (visual analogue scale or verbal) during rest or ambulation at any time of measurement. These results do not suggest that timing of analgesia with a conventional extradural regimen is of major clinical importance in patients undergoing colonic surgery.

COMPARISON OF THE RESPIRATORY EFFECTS OF I.V. INFUSIONS OF MORPHINE AND REGIONAL ANALGESIA BY EXTRADURAL BLOCK

The incidence of postoperative respiratory apnoea was compared between five patients receiving a continuous i.v. infusion of morphine (mean 73.6 mg) and five patients receiving a continuous extradural infusion of 0.25% bupivacaine (mean 192 mg) in the 24-h period following upper abdominal surgery. Monitoring consisted of airflow detection by a carbon dioxide analyser, chest wall movement detected by pneumatic capsules, and continuous electrocardiograph recorded with a Holter ambulatory monitor. Both obstructive (P less than 0.05) and central apnoea (P less than 0.05) occurred more frequently in patients who had a morphine infusion. There was also a higher incidence of tachyarrhythmias (P less than 0.05) and ventricular ectopic beats (P less than 0.05) in the morphine infusion group.

Comparison of Plasma Bupivacaine Concentrations During Continuous Extradural Infusion for Labour

Twenty patients who requested extradural analgesia for labour were allocated randomly to receive an infusion of either 0.25% or 0.08% solutions of bupivacaine. Following an initial bolus dose of 50 mg, the infusions were given at a rate of 20 mg h−1. Both solutions provided acceptable pain relief, but plasma concentrations were significantly lower with the weaker concentration.

EXTRADURAL BUPIVACAINE AND METHADONE FOR EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY

Combined extradural bupivacaine and methadone analgesia was investigated in 144 patients who underwent extracorporeal shock wave lithotripsy (ESWL). Patients were assigned randomly to one of three groups: group I--extradural 0.5% bupivacaine hydrochloride 0.75 mg kg-1; group II--extradural 0.1% methadone hydrochloride 4 mg after the bupivacaine; group III--as group II, plus a continuous extradural infusion of methadone 0.3 mg h-1 after operation. In all patients, only partial motor deficit occurred. During ESWL, patients who received extradural bupivacaine and methadone had significantly less pain compared with those who had bupivacaine alone (P less than 0.025). Extradural anaesthesia and immersion in the warm water bath were accompanied by only mild fluctuations in arterial pressure. After ESWL, significantly more patients with continuous methadone infusion were pain free (P less than 0.05) and they required less systemic analgesics. The anaesthesia during and after the ESWL procedure may be carried out safely and effectively by the administration of small doses of bupivacaine combined with methadone followed by infusion of the opioid.

CONTINUOUS EXTRADURAL INFUSION OF 0.125% BUPIVACAINE FOR PAIN RELIEF AFTER LOWER ABDOMINAL SURGERY

Twenty women, undergoing lower abdominal surgery, were allocated randomly to receive a continuous extradural infusion of either 0.125% bupivacaine or placebo at a rate of 15 ml h-1. All had received an intra-operative extradural block. Pain scores were recorded at 30, 60, 90, 120, 150, 180, 240 and 360 min after surgery. From 150 min onwards there was a significant benefit for those receiving the active drug. Six of nine patients in this group had adequate analgesia over the 6-h study period, while all patients in the placebo group required further pain relief.

POSTOPERATIVE ANALGESIA BY CONTINUOUS EXTRADURAL INFUSION OF BUPIVACAINE AND DIAMORPHINE

Three solutions administered by continuous extradural infusion for postoperative analgesia were compared in a randomized, double-blind manner. All patients underwent major abdominal gynaecological surgery and received 0.125% bupivacaine in 0.9% saline, diamorphine in 0.9% saline (0.5 mg in 15 ml) or diamorphine mixed with 0.125% bupivacaine (0.5 mg in 15 ml), at a rate of 15 ml h-1. The bupivacaine-diamorphine mixture provided significantly superior analgesia compared with either bupivacaine or diamorphine alone. No major side effects were encountered.

Pain treatment on outpatient basis utilizing extradural opiates. A danish multicentre study comprising 105 patients

Previous to October 1st, 1981, 8 major Danish anaesthesiological departments registered 105 patients treated with extradural opiates for a period of more than 7 days, partially or completely on outpatient basis. Ninety-four suffered from painful malignant diseases and 11 patients from various painful benign diseases. The mean period of treatment was 65 days (range: 7–283 days) and of these 49 days (2–266 days) as outpatients. The total number of inserted epidural catheters was 215, equivalent of an average of 2 per patient (range 1–5). Reasons for removing an extradural catheter were injection-related pain, difficulty in injecting the desired volume, and displacement of catheter. Morphine chloride, in a solution of 0.4 mg/ml of normal saline, was the main choice as analgesic agent (90 patients). The mean daily dose of this drug totalled 12.6 +- 4.8 mg (S.D.) (range: 4–30 mg) distributed as 2.7 +- 0.9 (S.D.) (range: 1–6) daily injections. Twelve patients were treated with buprenorphine extradurally. Satisfactory pain relief was achieved for 70 patients (67%) who managed with extradural opiates as sole analgesic treatment. One patient developed septicaemia with a non-fatal outcome probably originating from some other focus. Apart from this no serious side effects were reported. Medically unskilled persons or relatives were responsible for instillation of all extradural opiates with 42 patients and partially responsible with 14 patients. Eleven patients managed injections without assistance. District nurses took care of medication for 46 patients, aided by a general practitioner in 5 cases. Three patients were supplied with continuous extradural infusion by means of a Mill Hill R microinfusion pump.