Canadian Journal of Anaesthesia

, Volume 39, Issue 6, pp 537–544 | Cite as

Intraoperative clonidine enhances postoperative morphine patient-controlled analgesia

  • Marc F. De Kock
  • Georges Pichon
  • Jean -Louis Scholtes


In this prospective study, the postoperative analgesic effects of intraoperative iv clonidine were evaluated. Two hundred consecutive patients undergoing major abdominal surgery were randomly assigned to either balanced anaesthesia with iv clonidine (Group 1)or balanced anaesthesia alone (Group 2). A PCA infuser was connected immediately after tracheal extubation. It was programmed to deliver morphine “on demand” iv boluses at doses of I mg for patients >65 yr and 1.5 mg for women or 2 mgfor men <65 yr old. A blinded observer assessed postoperative analgesia by recording the analgesic demands (both met and unmet), patient pain scores, sedation scores, and any side effects during the first 36 hr after surgery. Intraoperative clonidine reduced the number of analgesic demands during the observation period (45 ± 27 demands in Group 1 vs 81 ±60 in Group 2, P = 0.0001). This resulted in a reduction in morphine delivered (55.4 ± 30.6 mg vs 67.1 ± 45.1 mg, P < 0.05), mainly during the first 12 hr (19.7 ± 11.1 mg vs 27.6 ±18.1, mg P < 0.001) and the unmet demand rate was also reduced at all time intervals (P < 0.01). Clonidine did not exacerbate sédation or side effects. However, clonidine provided better analgesia in men and in patients <65 yr of age. Intraoperative iv clonidine enhances morphine analgesia after abdominal surgery.

Key words

analgesia: postoperative analgesics: morphine sympathetic nervous system: pharmacology, clonidine 


Cette étude prospective a pour but d’évaluer les effets analgésiques postopératoires de la clonidine administrée par voie iv durant la chirurgie. Deux cents patients admis pour chirurgie abdominale majeure sont distribués de façon aléatoire en deux groupes égaux selon la technique anesthésique utilisée: les patients du groupe 1 ont une anesthésie balancée incluant de la clonidine iv, et ceux du groupe 2, une anesthésie balancée sans clonidine. L’analgésie postopératoire est débutée immédiatement après l’extubation tracheale à l’aide d’une pompe contrôlée par le patient. La pompe permet une administration à la demande de morphine iv. Les doses de morphine sont de 1 mg pour les patients âgés de plus de 65 ans, 1,5 mg pour les femmes et 2 mg pour les hommes de moins de 65 ans. L’intervalle entre les doses est de 7 minutes, avec un maximum de 30 mg pour chaque periode de 4 heures. Un observateur non informé de la technique anesthésique utilisée pour chaque patient evalue l’analgesie postoperatoire. Les paramètres évalués sont le total des demandes analgésiques (celles avec ou sans administration de morphine), l’échelle de douleur, l’échelle de sédation et les effets secondaires durant les 36 heures suivant la chirurgie. Le nombre de demandes analgésiques est de 45 ±27 dans le groupe 1 versus 81 ± 60 dans le groupe 2 (P = 0,0001). Ceci se traduit par une moindre utilisation de morphine dans le groupe 1, soit 55,4 ± 30,6 mg versus 67,1 ± 45,1 mg dans le groupe 2 (P < 0,05); cette difference est plus marquee dans les 12 premiéres heures après la chirurgie (19,7 ± 11,1 mg versus 27,6 ± 18,1 mg; P < 0,001). L’administration de clonidine iv n’est pas associee a une sédation plus importante ou une incidence plus élevée d’effets secondaires. Les effets analgésiques de la clonidine sont plus marqués chez les hommes et chez les patients de moins de 65 ans. En conclusion, la clonidine iv administrée durant la chirurgie augmentent les effets analgésiques de la morphine suite a une chirurgie abdominale.


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Copyright information

© Canadian Anesthesiologists 1992

Authors and Affiliations

  • Marc F. De Kock
    • 1
  • Georges Pichon
    • 1
  • Jean -Louis Scholtes
    • 1
  1. 1.Department of AnesthesiologyUniversity of LouvainBrusselsBelgium

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