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From the Department of Anesthesiology and Department of Orthopedics, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong.
Address correspondence to: Dr. Peter H.K. Mak. Phone: 852-28555791; Fax: 852-28553384; E-mail: makphk{at}hkstar.com
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Abstract |
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Clinical Features: A 34-yr-old man had contractures of the fingers of his dominant hand following a crush injury in 1996. After several operations, he continued to experience severe pain and disability. In order to facilitate pain-free active and passive physiotherapy, we performed an axillary brachial plexus block. After insertion of a brachial plexus catheter via the axilla, analgesia was continued for a period of one week using a 3 ml•hr–1 background infusion of ropivacaine 0.2% with the facility for additional patient-controlled 1 ml boluses. Both active and passive physiotherapy was carried out daily for the entire week.
Conclusion: This technique was successful with no major complications and resulted in a marked reduction in pain, with improved range of finger movement and general upper limb function.
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Case history |
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At presentation, he had marked pain during active and passive movement of his fingers and recorded a zero to ten visual analogue score for pain (VAS) of 5 at rest. Following an explanation of brachial plexus block and patient-controlled analgesia (PCA), informed consent was obtained. A brachial plexus block was performed via the axillary approach using an 18G Tuohy needle with a nerve stimulator (Innervator NS272, Fisher & Paykel Health Care). A 14G intravenous catheter sheath (Angiocath, Becton Dickinson) provided insulation for the needle. A corresponding size epidural catheter was inserted through the Tuohy needle that was then removed, and 20 ml of ropivacaine 0.2% were injected slowly through the catheter. Eight centimeters of catheter were left in the axilla for infusion of local anesthetic. A PCA pump (Graseby 9300 Ambulatory Infusion Pump, Graseby Medical, UK) was used to provide a background infusion of ropivacaine 0.2% at 3 ml•hr–1 (6 mg•hr–1) with the facility for a 1 ml (2mg) bolus on patient demand. The lock-out interval was set at 10 min with a maximum hourly limit of 5 ml (10 mg) including both the background infusion and the PCA boluses.
The visual analogue pain score decreased to zero following institution of the block. Due to the large initial bolus dose (20 ml ropivacaine 0.2%), there was also a considerable degree of motor paralysis. He was not able to lift up his shoulder nor could he move his elbow and wrist. The next day, much of the hypoesthesia in his arm, especially over the distribution of the ulnar nerve, had dissipated but his VAS remained 0–2. Active physiotherapy was being carried out twice a day and a passive physiotherapy device (Mobilimb H2, Hand CPM, Toronto Medical, Canada) was being used for continuous flexion and extension of the middle finger. The catheter remained in situ for a further six days without evidence of site infection.
An observation chart was used by the ward nursing staff to document vital signs, VAS, muscle power (shoulder, elbow and hand), touch sensation by cotton wool ball and any signs of local anesthetic toxicity (dizziness, oral numbness). The observations were done four-hourly. The VAS score remained at 2–3 throughout the six days and he only had 14 additional PCA demands (all successful). The ropivacaine infusion rate was increased to 3.5 ml (7 mg•hr–1) on day 4 following the patient's request for more analgesia. The total cumulative dose of ropivacaine given to the patient was 452 ml (904 mg), an average of 6.79 mg•hr–1.
There was a considerable improvement in mobility of his fingers during and after the ropivacaine infusion (Table I
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). However, during the last three days, after a dressing change on day four, his hand power was reduced to 3–4 after an increase in the infusion rate from 6 mg•hr–1 to 7 mg•hr–1.
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). His pain score remained at 2–3 after cessation of the infusion. He continued to receive active physiotherapy three times per week and both his contractures and function were much improved. Further tendon transfers to thumb and middle finger were performed to improve the range of movement and strength of the digits. |
Discussion |
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We chose to use ropivacaine because it is reported to be less cardiotoxic and to preserve muscle movement better than other long acting local anesthetic drugs.3,4 There is only one report of ropivacaine infusion on the brachial plexus and it was used to treat phantom limb pain.5 It was found to be an extremely useful technique; not only providing analgesia but also preserving muscle power in the upper limbs.
We used a concentration of ropivacaine 0.2% to restrict the infusion volume and minimize the pressure inside the brachial plexus sheath. With any local anesthetic infusion technique, there is always the potential for systemic toxicity because of drug absorption or catheter migration. An initial infusion rate of 6 mg•hr–1 is unlikely to cause systemic toxicity but as the patient had the ability to increase the dosage via PCA, and there is always a danger of man-made or mechanical malfunction of any infusion device, it was important for us to initiate an effective monitoring protocol for early detection and treatment. We did this by measuring blood pressure, heart rate and observing central nervous system signs such as consciousness, dizziness and perioral paresthesia four-hourly. We also made the patient aware of these risks and encouraged him to report any problems. Based on these clinical observations, there were no complications during the six-day infusion. However, we did not have the appropriate laboratory facilities to measure actual ropivacaine blood concentration.6,7
Due to the selectivity of ropivacaine blockade for sensory nerves, muscle movement should be better preserved than with bupivacaine.8 This was particularly beneficial since both active and passive physiotherapy could be undertaken effectively during the infusion period, with minimal pain and good muscle power. Continuous motion machines were used throughout the day and night to improve passive range of movement and prevent further deterioration. Strengthening exercises are also possible in pain free digits.
One disadvantage of our technique is the possibility of catheter related infection,9 although this was not a problem in this case. It is often related to the site and duration of insertion and a potential improvement may be to introduce the catheter via a ‘tunnel' under the skin, similar to the insertion of a parenteral nutrition catheter for prolonged intravenous use. The exit site of the catheter could then be further away from the axilla, a site that may have a higher potential to become infected.
Although a single case report would not be able to provide sufficient information to conclude that ropivacaine is a safer drug to use in this context, it is our opinion that it is a more logical choice due to its lower potential for systemic toxicity and lack of motor blockade.
The patient was reviewed at the pain clinic four weeks after discharge and in the orthopedic outpatient clinic three months later. He still experiences much less pain, even during physiotherapy (VAS=2), and movement of his hand and fingers continues to improve.
Accepted for publication May 6, 2000.
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References |
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2 Rawal N, Axelsson K, Hylander J, et al. Postoperative patient-controlled local anesthetic administration at home. Anesth Analg 1998; 86: 86–9.[Medline]
3
Scott DB, Lee A, Fagan D, Bowler GMR, Bloomfield P, Lundh R. Acute toxicity of ropivacaine compared with that of bupivacaine. Anesth Analg 1989; 69: 563–9.
4
Morrison LMM, Emanuelsson BM, McClure JH, et al. Efficacy and kinetics of extradural ropivacaine: comparison with bupivacaine. Br J Anaesth 1994; 72: 164–9.
5 Lierz P, Schroegendorfer K, Choi S, Felleiter P, Kress H-G. Continuous blockade of both brachial plexus with ropivacaine in phantom pain: a case report. Pain 1998; 78: 135–7.[Medline]
6 Tuominen M, Pitkänen M, Rosenberg PH. Postoperative pain relief and bupivacaine plasma levels during continuous interscalene brachial plexus block. Acta Anaesthesiol Scand 1987; 31: 276–8.[Medline]
7 Emanuelsson B-MK, Persson J, Alm C, Heller A, Gustafsson LL. Systemic absorption and block after epidural injection of ropivacaine in healthy volunteers. Anesthesiology 1997; 87: 1309–17.[Medline]
8 Markham A, Faulds D. Ropivacaine. A review of its pharmacology and therapeutic use in regional anaesthesia. Drugs 1996; 52: 429–49.[Medline]
9 Aguilar JL, Domingo V, Samper D, Roca G, Vidal F. Long-term brachial plexus anaesthesia using a subcutaneous implantable injection system. Reg Anesth 1995; 20: 242–5.[Medline]
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