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Correspondence  |   April 2001
The Effect of Lumbar Plexus Block on Blood Loss and Postoperative Pain
Author Affiliations & Notes
  • Robert Stevens, M.D.
    *
  • *Geneva University Hospitals, Geneva, Switzerland. Robert.Stevens@hcuge.ch
Article Information
Correspondence
Correspondence   |   April 2001
The Effect of Lumbar Plexus Block on Blood Loss and Postoperative Pain
Anesthesiology 4 2001, Vol.94, 717. doi:
Anesthesiology 4 2001, Vol.94, 717. doi:
In Reply:—
We appreciate the interest expressed by Ekatodramis et al.  regarding our recent article. 1 The principal objective of our study was to determine whether postoperative pain and analgesic use in the setting of prosthetic hip replacement were influenced significantly by lumbar plexus block. We also assessed a number of secondary endpoints, such as blood loss. At our institution, evaluation of operative blood loss related to orthopedic surgery is a standardized procedure and involves determining the quantity of blood in suction canisters and counting the number of surgical dressings. The volume of blood per dressing depends on the size and type of dressing and on the quantity of blood it has absorbed. With the dressings used for this type of surgery at our hospital, we have observed reproducibly a quantity of blood approximating 40 ml. Using this method of evaluation, we have obtained an excellent correlation with blood losses calculated using preoperative and postoperative hematocrits.
The question regarding the statistical tests used for comparing Visual Analogue Scale scores between groups is legitimate. We assumed that the distribution of results was Gaussian and therefore used the Student t  and chi-square tests where relevant. However, to test the suggestion of Ekatodramis et al.  , we reanalyzed the data assuming a nonnormal distribution and performing the pertinent nonparametric tests (Wilcoxon rank sum test or Mann-Whitney U test) and obtained nearly identical P  values, which confirms our initial assumption of a normal distribution.
We can only agree that it is important to define time points clearly in studies of postoperative outcome. In our article, parameters related to analgesia (Visual Analogue Scale scores and morphine consumption) are expressed consistently as a function of the time elapsed after randomization. In one figure (3A) representing pain scores in the postanesthesia care unit, the time origin was modified deliberately to enhance clarity. This modification is explicit, and we do not believe it introduces significant bias.
The exclusion criteria given in the text summarize contraindications that are known and accepted by most providers of regional anesthesia and therefore were not reported in full. They include major coagulation abnormalities, sepsis at the site of injection, and hypersensitivity to local anesthetics. We did not exclude patients with diabetes mellitus or those with stable peripheral neuropathy.
Finally, the issue of administering nerve blocks to patients undergoing general anesthesia has already been addressed in a previous exchange of letters. 2,3 Although we concur that performing blocks in individuals who are awake is an intuitively sound anesthetic practice, several large-scale studies have not shown increased risk of nerve injury when the procedures are performed in anesthetized patients. 4,5 
*Geneva University Hospitals, Geneva, Switzerland. Robert.Stevens@hcuge.ch
References
Stevens RD, Van Gessel E, Flory N, Fournier R, Gamulin Z: Lumbar plexus block reduces pain and blood loss associated with total hip arthroplasty. A nesthesiology 2000; 93: 115–21Stevens, RD Van Gessel, E Flory, N Fournier, R Gamulin, Z
Singer T, Bird P, Borgeat A:“3-in-1” femoral block (letter). Can J Anaesth 1998; 45: 1032Singer, T Bird, P Borgeat, A
Fournier R, Van Gessel E, Gaggero G, Boccovi S, Forster A, Gamulin Z:“3-in-1” femoral block (letter). Can J Anaesth 1998; 45:1032. Can J Anaesth 1998; 45:1033
Giaufré E, Dalens B, Gombert A: Epidemiology and morbidity of regional anesthesia in children: A one-year prospective survey of the French-Language Society of Pediatric Anaesthesiologists. Anesth Analg 1996; 83: 904–12Giaufré, E Dalens, B Gombert, A
Choquet O, Feugas JL: Neurostimulation sous anesthésie générale et traumatisme nerveux périphérique. Ann Fr Anesth Reanim 1997; 16: 923–8Choquet, O Feugas, JL