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Dextromethorphan attenuation of postoperative pain and primary and secondary thermal hyperalgesia


Purpose: To determine the effect of 90 mg dextromethorphan (DM)po vs placebo 90 min preoperatively, on the immediate and delayed postoperative course.

Methods: Thirty patients undergoing laparoscopic cholecystectomy or inguinal hernioplasty under general anesthesia were studied. Half (DM) received 90 mg dextromethorphan and half received placebo 90 min before anesthesia. Intravenous Patient Controlled Aanalgesia with morphine was available for two hours within a six-hour observation period; 75 mg diclofenacim prn was given later in PACU and on-ward (24 hr). Pain was assessed using the visual analogue scales. Thermal thresholds for cold and hot sensation and for pain (by limit method) were evaluated at the site of skin incision (primary-) and distantly (secondary hyperalgesia). Von Frey filaments were applied testing touch sensation. Sedation level and morphine consumption were also assessed in PACU.

Results: Demographic, surgical and perioperative parameters were similar; no untoward effects were encountered. Pain intensity and sedation were lower, and the feeling of well-being was greater, in the DM patients: onevs five (median), twovs five, fivevs two, respectively,P<0.01 (90 min time-point). Thermal application revealed absence of primary and secondary hyperalgesia only in the DM patients; von Frey filaments induced similar pain sensation in both groups. Mean morphine/group, morphine/weight and diclofenac injection rates were ∼55% lower in the DM group: 2.1±1.2 (SD)vs 4.7±2.3, 0.03±0.02vs 0.07±0.03, 1.0±0.3vs 2.4±0.2, respectively,P<0.01.

Conclusions: Compared with placebo, DM enabled reduction of postoperative analgesics consumption, improved well-being, and reduced sedation, pain intensity and primary and secondary thermal hyperalgesia.


Objectif: Déterminer l’effet de 90 mg de dextrométhorphane (DM)po vs un placebo, administrés 90 min avant l’opération, sur l’évolution postopératoire immédiate et tardive.

Méthode: L’étude a porté sur 30 patients devant subir une cholécystectomie laparoscopique ou un hernioplastie inguinale. La moitié a reçu 90 mg de dextrométhorphane et l’autre moitié, un placebo, 90 min avant le début de l’anesthésie générale. La morphine, en qualité d’analgésie intraveineuse autocontrôlée, a été disponible pendant deux heures sur une période d’observation de six heures; 75 mg de diclofénacim prn ont été administrés plus tard à la salle de réveil et à la chambre (24 h). La douleur a été évalué grâce à l’échelle visuelle analogique. Les seuils thermiques de sensation au froid et à la chaleur ainsi qu’à la douleur (selon une méthode du seuil différentiel) ont été évalués au site de l’incision cutanée (hyperalgésie primaire) et à distance (hyperalgésie secondaire). Des filaments von Frey ont été appliqués pour tester le toucher. On a aussi évalué, à la salle de réveil, le niveau de sédation et la consommation de morphine.

Résultats: Les paramètres démographiques, chirurgicaux et périopératoires ont été similaires: aucun effet indésirable n’a été noté. L’intensité de la douleur et de la sédation a été plus faible, et le confort meilleur, chez les patients du groupe DM: unvs cinq (médiane), deuxvs cinq, cinqvs deux, respectivement,P<0,01 (90 min après le début de l’analgésie). L’épreuve de sensibilité thermique a révélé l’absence d’hyperalgésie primaire et secondaire chez les patients du groupe DM seulement; les filaments von Frey ont induit une sensation de douleur similaire chez les patients des deux groupes. La consommation moyenne de morphine selon le groupe et selon le poids des patients ainsi que les taux d’injection de diclofénac ont été de ∼55% plus bas dans le groupe DM: 2,1±1,2 (écart type)vs 4,7±2,3; 0,03±0,02vs 0,07±0,03; 1,0±0,3vs 2,4±0,2, respectivement,P<0,01.

Conclusion: Comparé à un placebo, le DM a permis de réduire la consommation d’analgésiques postopératoires, a amélioré le confort et a réduit la sédation, l’intensité de la douleur et l’hyperalgésie thermique primaire et secondaire.


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Correspondence to Avi A. Weinbroum.

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Weinbroum, A.A., Gorodezky, A., Niv, D. et al. Dextromethorphan attenuation of postoperative pain and primary and secondary thermal hyperalgesia. Can J Anaesth 48, 167 (2001).

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  • Morphine
  • Pain Intensity
  • Dextromethorphan
  • Post Anesthesia Care Unit
  • Morphine Consumption