Management of postoperative pain is one of the most challenging and gratifying domains of anaesthesia. Use of epidural blockade has increased steadily in popularity for the management of moderate to severe pain following orthopaedic surgery. However, the cost and complexity of managing epidural infusion postoperatively in the wards or at home is a major disadvantage. Relatively inexpensive disposable non-mechanical elastomeric balloon pump, not requiring much intervention make epidural infusion easy to manage and has revolutionized pain management. In our study we compared tramadol bolus and infusion with bupivacaine infusion using elastomeric balloon pump.

A disposable non-mechanical elastomeric balloon pump was used for the infusion cases. It consists of two-layers of elastic membrane; the inner layer is composed of a special blend polymer with a latex outer layer. The two membranes have an outer cover of soft PVC as additional protection. The latex outer layer at no time comes into contact with the infusion fluid. It has an extension line with one-way filling valve, clamp, and filter for air and particulate matter. After filling it runs for continuously without any need for interference. It is easy to manage and portable. As it is non-programmable it is possible to use at home. It is relatively inexpensive.

After appropriate institutional ethics committee approval 90 ASA I and II patients undergoing lower limb surgery between the age group 21-60 years and weighing 35-79 kg were studied in a prospective randomized comparative study. After routine preoperative assessment and investigations, patients were explained the anaesthesia procedure and an informed consent was taken. Patients with a history of hepatic, renal or circulatory disorders, drug allergy, chronic headache, backache, neurological deficit or pregnancy were excluded from the study.

Three groups were : Group A : Tramadol bolus 2 mg/kg in 10 ml NS 8 hourly for 50 hours. Group B : Tramadol infusion 2-2.5 mg/ml (5 ml/hr) for 50 hours. Group C : Bupivacaine infusion 0.125% (5 ml/hr) for 50 hours.

Age, weight and preoperative vital parameters were noted. All patients received 0.6 mg of Inj. Glycopyrolate IM 30 minutes prior to administration of anaesthesia. They were preloaded with 500 ml of ringer lactate. With due aseptic precautions CSE technique was used using 16G set. 15-20 mg of 0.5% heavy bupivacaine was used to give sub-arachnoid block and when level receded below T10, epidural infusion of 0.375% bupivacaine was started. It was continued till the end of surgery. Postoperatively one of the 3 modalities of analgesia was randomly selected and the patient was shifted to the recovery room. VAS was monitored and adverse effects were looked for and appropriately treated. Patients were monitored every 30 minutes for first 4 hours and then 2 hourly for 50 hours. Patients were asked to grade pain on a scale of 0-10 points where 0 was no pain and 10 was worst pain. Rescue analgesia in the form of IM diclofenac (1.5 mg/kg) was given when VAS was ³ 5.

Adverse effects like nausea, vomiting, pruritus, headache, respiratory depression, abdominal distension, paraesthesia, and motor weakness were looked for and appropriately treated. Unpaired students ‘t’ test was used to analyze numerical data while Chi-square test was used for categorical data. P < 0.05 was considered as significant (*).

80% of bolus group patients needed rescue analgesia as compared to 20% and 13% patients in the tramadol and bupivacaine infusion groups respectively.

No significant changes in respiratory or haemodynamic parameters were seen. Incidence of nausea and vomiting was seen only in tramadol group. In bolus group 6 patients experienced nausea and 2 had vomiting while in infusion group 14 had nausea and 6 had vomiting which subsided with IV on-dansetron. Abdominal distension was also noted only in tramadol group, which was relieved by passing RT/flatus tube. Two patients in bupivacaine infusion group had transient paraesthesia and motor weakness, which recovered on stoppage of infusion.

NSAIDs and weak opioids are adequate for mild to moderate pain; these drugs may be ineffective in patients with moderate to severe pain. Local anaesthetics as well as opioids have been demonstrated to be highly effective analgesics. The main limitation to its widespread use is the need for repeated administration. Continuous infusion overcomes this difficulty and avoids fluctuations in the level of analgesia.

We found that 2-2.5 mg/ml @ 5 ml/hr of tramadol infusion provides better pain relief than 2 mg/kg bolus which is similar to results obtained by Rud and Fischer et al.8 Siddik et al5 found that duration of analgesia after 100 mg of tramadol given epidurally to be 4.5 ± 3.1 hours, where as Dellikan et al have reported it to be 9.36 hours. We found analgesic effect to last for 5.46 ± 1.25 hours subject to patient variability. We report lower VAS with bupivacaine infusion as compared to tramadol infusion or bolus. Lin WQ et al2 obtained similar results. Side effects like nausea, vomiting was much more in the tramadol infusion group that subsided with IV ondansetron. Two patients in the same group had abdominal distension and in 1 patient in the bolus group, for which Ryle’s tube and flatus tube was passed. Two patients in bupivacaine group complained of transient paraesthesia and one of motor weakness, which was relieved after infusion was stopped.

Twenty four patients in bolus group required rescue analgesic as against only 6 in tramadol infusion group and 4 in bupivacaine group. Hence continuous infusion avoided fluctuations, maintaining a steady level of analgesia. Bupivacaine infusion provided better pain relief with lesser side effects. Thus local anaesthetic infusions using elastomeric balloon pumps can be used to provide steady and safe pain relief in patients with moderate to severe pain in the post-operative period.