Effects of intrathecal ketamine added to bupivacaine for spinal anaesthesia

We prospectively studied 30 healthy female patients undergoing intracavitor y brachytherapy applicator insertion for carcinoma of the cervix under spin al anaesthesia. Patients were randomly allocated to receive either intrathe cal bupivacaine 10 mg alone or bupivacaine 7.5 mg combined with preservativ e-free ketamine 25 mg. Spinal block onset, maximum sensory level, duration of blockade, haemodynamic variables, postoperative analgesic requirements a nd adverse events were recorded. Onset of sensory and motor block and durat ion of spinal analgesia were comparable between groups. Duration of motor b lockade was shorter (p = 0.0416) and requirement for intravenous fluids in the peri-operative period was less (p = 0.0159) in the ketamine group. Sign ificantly more patients in the ketamine group had adverse events, such as s edation, dizziness, nystagmus, 'strange feelings' and postoperative nausea and vomiting. Although the addition of ketamine to spinal bupivacaine had l ocal anaesthetic sparing effects, it did not provide extended postoperative analgesia or decrease the postoperative analgesic requirements. Moreover, the central adverse effects of ketamine limit its spinal application.