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well with cardiac output (CO) with impending cardiovascular collapse or at the late period of bupivacaineinduced cardiotoxicity. The article by Beal et al.2 showed the changes of hemodynamics (CO decreased and mean systolic blood pressure remained unchanged) in the early period of bupivacaine (cardiac) intoxication. The concept of early and late bupivacaine cardiotoxicity is based on the results of Cho et al.3 and its definition can be found in our article.1 An earlier study showed that a plasma bupivacaine concentration of 1 to 2 µg·mL–1 increased BP and decreased CO.4 CO does not always decrease with bupivacaine administration. After convulsive doses (1 mg·kg–1), CO increases.5 In addition, the bupivacaine concentration in our study was much higher than in Beal et al.’s. We appreciate Drs. Freysz and Lenfant’s comments but, in our view, both studies were quite different. Jin-Tae Kim MD Kook-Hyun Lee Seoul, Korea

MD

References 1 Kim JT, Rhee KY, Bahk JH, et al. Continuous mixed venous oxygen saturation, not mean blood pressure, is associated with early bupivacaine cardiotoxicity in dogs. Can J Anesth 2003; 50: 376–81. 2 Beal JL, Freysz M, Timour Q, Bertrix L, Lang J, Faucon G. Haemodynamic effects of high plasma concentrations of bupivacaine in the dog. Eur J Anaesthesiol 1988; 5: 251–60. 3 Cho HS, Lee JJ, Chung IS, Shin BS, Kim JA, Lee KH. Insulin reverses bupivacaine-induced cardiac depression in dogs. Anesth Analg 2000; 91: 1096–102. 4 Hasselstrom LJ, Mogensen T, Kehlet H, Christensen NJ. Effects of intravenous bupivacaine on cardiovascular function and plasma catecholamine levels in humans. Anesth Analg 1984; 63: 1053–8. 5 Rutten AJ, Nancarrow C, Mather LE, Ilsley AH, Runciman WB, Upton RN. Hemodynamic and central nervous system effects of intravenous bolus doses of lidocaine, bupivacaine, and ropivacaine in sheep. Anesth Analg 1989; 69: 291–9.

Intrathecal morphine vs psoas compartment block for hip surgery To the Editor: Souron et al. point out that the innervation to the hip joint arises from the lumbar as well as the sacral plexus and that analgesia will be incomplete with a psoas

compartment block alone.1 The lateral cutaneous nerve of the thigh (LCNT) can still be missed in about 5% of cases.2 Cross innervation from the gluteal nerves into the LCNT territory and the relatively low volume of local anesthetic used in this study may equally have contributed to a reduced success rate. A single shot psoas block is also known to have a shorter duration of action compared with intrathecal morphine. A central neuraxial technique will always be more reliable. In our view the authors are comparing apples with oranges. We use a continuous psoas compartment block, combined with a single shot parasacral block, as described by Mansour.3 The psoas block is initiated with 40 mL of prilocaine 1% and 10 mL of bupivacaine 0.5%. For the parasacral block we use 20 mL of bupivacaine 0.5%. In conjunction with general anesthesia no further analgesia is required intraoperatively. A further bolus of 20 mL of bupivacaine 0.25% is required after about six hours. Postoperative analgesia is provided with a continuous infusion of bupivacaine 0.125% at 10 mL·hr–1 until 12 hr before mobilization. Using this technique our patients often complain about pain in the back and other joints unrelated to their surgery. Souron et al. do not refer to the site of pain in their patients, making pain scores on their own unreliable in comparing the effectiveness of these two techniques. Kate Paterson Joerg Kuehne Surrey, UK

BSc MBCHB FRCA FRCA

References 1 Souron V, Delaunay L, Schifrine P. Intrathecal morphine provides better postoperative analgesia than psoas compartment block after primary hip arthroplasty. Can J Anesth 2003; 50: 574–9. 2 Tokat O, Turker YG, Uckunkaya N, Yilmazlar A. A clinical comparison of psoas compartment and inguinal paravascular blocks combined with sciatic nerve block. J Int Med Res 2002; 30: 161–7. 3 Mansour NY. Reevaluating the sciatic nerve block: another landmark for consideration. Reg Anesth 1993; 18: 322–3.

R E P LY : I thank Drs. Paterson and Kuehne for their comments on our article.1 Unfortunately, I radically disagree with their comments. First, the comparison between analgesia techniques is a very common research subject in the anesthesia literature, even when these techniques appear to be different in

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terms of route of administration (for example iv morpine patient-controlled analgesia, epidural analgesia and femoral block for total knee arthroplasty).1 The recent articles on the use of single shot psoas compartment block and intrathecal morphine injection for pain relief after total hip arthroplasty (THA) prompted us to conduct our study. Drs. Paterson and Kuehne explain themselves the anatomical reasons why the psoas block cannot provide similar pain relief than intrathecal morphine: the innervation of the hip does not depend only on the lumbar plexus, but also on the sacral plexus. In their description, they forget that the last thoracic root (T12) innervates the upper part of the incision. However, it is well known that postoperative pain after THA does not depend on cutaneous stimuli. They combine a psoas block with a single shot sciatic block without considering the risks of Mansour’s block (rectal perforation, iliac vessel or ureter injury). Furthermore, they seem to forget another concern, the systemic toxicity of local anesthetics and/or the risk of massive intrathecal or intravascular injection (their combined sacral and lumbar blocks require 30 mL of 0.5% bupivacaine and 40 mL of prilocaine!). The volume of ropivacaine 0.475% used in our study (25 mL) is comparable with the volumes recommended for psoas compartment block (0.4 mL·kg–1 of bupivacaine 0.5%)2 and, thus, cannot be considered low. In addition, there is no study comparing the duration of analgesia with both techniques. To our knowledge, the only reference regarding continuous psoas compartment block for pain relief after THA is the descriptive study by Capdevila et al.3 Drs. Paterson and Kuehne do not produce any data to support their assertion that the combination of parasacral and psoas blocks is the ideal technique to provide postoperative analgesia after THA. Concerning their last comment on the site of postoperative pain after THA, we believe that the only concern with our assessment is not its location but the fact that we did not differentiate between pain at rest and during motion. Paterson and Kuehne say we are comparing apples and oranges. Nevertheless “primum non nocere” is our duty. Our results show that low dose intrathecal morphine provides better postoperative pain relief than psoas compartment block after THA. The only side effect was urinary retention requiring bladder catheterization. With psoas compartment blocks, disastrous complications have been described with an incidence of 8/1000.4 Anesthesiologists should always keep in mind the benefit/risk ratio of the techniques they use to provide relief.

Vincent Souron Annecy, France

MD

References 1 Singelyn FJ, Deyaert M, Joris D, Pendeville E, Gouverneur JM. Effects of intravenous patient-controlled anlagesia with morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg 1998; 87: 88–92. 2 Stevens RD, Van Gessel E, Flory N, Fournier R, Gamulin Z. Lumbar plexus block reduces pain and blood loss associated with total hip arthroplasty. Anesthesiology 2000; 93: 115–21. 3 Capdevila X, Macaire P, Dadure C, et al. Continuous psoas compartment block for postoperative analgesia after total hip arthroplasty: new landmarks, technical guidelines, and clinical evaluation. Anesth Analg 2002; 94: 1606–13. 4 Auroy Y, Benhamou D, Bargues L, et al. Major complications of regional anesthesia in France: the SOS regional anesthesia hotline service. Anesthesiology 2002; 97: 1274–80.

The infraclavicular block is a useful technique for emergency upper extremity analgesia To the Editor: The infraclavicular (IC) brachial plexus block is an effective but underused technique. We highlight the interest of such an approach performed in emergency conditions. An IC coracoid block was performed in the emergency department in a 17-yr-old male with a dislocated elbow complaining of severe pain (100 mm on the visual analogue scale - VAS). After appropriate motor responses at less than 0.6 mA (100 µsec), 7 mL and 23 mL of mepivacaine 1% were injected on the musculocutaneous and the median nerves respectively. Total duration of the procedure was two minutes. Ten minutes later the patient was pain-free with a profound sensory and motor block of the upper limb allowing successful reduction of the dislocation. After immobilization, the patient was sent home. A 27-yr-old male with a complex fracture and dislocation of the right wrist complained of excruciating pain (100 mm on the VAS) despite 30 mg morphine iv. Forty millilitres of ropivacaine 0.75% were injected through an IC catheter inserted using a nerve stimulator according to the technique described by Wilson