Purpose Perioperative intravenous ketamine may be a useful addition in pain management regimens. Previous systematic reviews have included all methods of ketamine administration, and heterogeneity between studies has been substantial. This study addresses this issue by narrowing the inclusion criteria, using a random effects model, and performing subgroup analysis to determine the specific types of patients, surgery, and clinical indications which may benefit from perioperative ketamine administration. Source We included published studies from 1966 to 2010 which were randomized, double-blinded, and placebocontrolled using intravenous ketamine (bolus or infusion) to decrease postoperative pain. Studies using any form of regional anesthesia were excluded. No limitation was placed on the ketamine dose, patient age, or language of publication. Principal findings Ninety-one comparisons in seventy studies involving 4,701 patients met the inclusion criteria (2,652 in ketamine groups and 2,049 in placebo groups). Forty-seven of these studies were appropriate for evaluation in the core meta-analysis, and the remaining 23 studies were used to corroborate the results. A reduction in total opioid consumption and an increase in the time to first analgesic were observed across all studies (P \ 0.001). The greatest efficacy was found for thoracic, upper abdominal, and major orthopedic surgical subgroups. Despite using less opioid, 25 out of 32 treatment groups (78%) experienced less pain than the placebo groups at some point postoperatively when ketamine was efficacious. This finding implies an improved quality of pain control in addition to decreased opioid consumption. Hallucinations and nightmares were more common with ketamine but sedation was not. When ketamine was efficacious for pain, postoperative nausea and vomiting was less frequent in the ketamine group. The dose-dependent role of ketamine analgesia could not be determined. Conclusion Intravenous ketamine is an effective adjunct for postoperative analgesia. Particular benefit was observed in painful procedures, including upper abdominal, thoracic, and major orthopedic surgeries. The analgesic effect of ketamine was independent of the type of intraoperative opioid administered, timing of ketamine administration, and ketamine dose.
RésuméObjectif La ke´tamine intraveineuse pe´riope´ratoire peut constituer un ajout utile a`l'arsenal the´rapeutique de prise en charge de la douleur. Les revues me´thodiques pre´ce´dentes ont examine´toutes les me´thodes d'administration de la ke´tamine, et l'he´te´roge´ne´ite´entre les e´tudes est conside´rable. Cette e´tude aborde la question en limitant les crite`res d'inclusion, en utilisant un mode`le a`effets ale´atoires et en re´alisant une analyse de sous-groupe afin de de´terminer les types spe´cifiques de patients et de chirurgie ainsi que les indications cliniques qui pourraient be´ne´ficier de l'administration pe´riope´ratoire de ke´tamine.