Intrathecal Ketamine for War Surgery. A Preliminary Study Under Field Conditions

Intrathecal ketamine, which has not previously been described in man, has been administered to 16 patients with war injuries of the lower limbs. The first five received varying doses from 5 to 50 mg in a volume of 3 ml of 5% dextrose, to determine a dose-response curve (Group 1). The optimal dose was then administered to a further 11 patients who received ketamine 50 mg in a volume of 3 ml in 5% dextrose with the addition of adrenaline 0.1 mg (Group 2). A distinct sensory level was obtained in all patients. In Group 2, nine of the eleven patients obtained satisfactory surgical analgesia and two required supplementation with local anaesthetic. Central effects (drowsiness, dizziness, and nystagmus) also occurred in nine patients, but they remained conscious throughout; one patient experienced no central effects, and one patient developed dissociative anaesthesia. Central effects were more intense the higher level of block. There were no significant changes in mean systolic arterial blood pressure, pulse, or respiratory rates. Surgical analgesia for the blocked dermatomes lasted for a mean of 58 minutes (range 45-90), and recovery was complete and uncomplicated; mild generalised analgesia persisted for a further one to three hours following return of sensation. Ketamine alone did not produce motor block, but addition of adrenaline resulted in complete motor block, and may have intensified sensory blockade. Motor loss persisted for the same duration as surgical analgesia. Adrenaline neither delayed the onset of central effects, nor reduced their intensity.(ABSTRACT TRUNCATED AT 250 WORDS)