Spread of spinal block in patients with rheumatoid arthritis.

Background: In clinical practice, we noticed a greater than expected spread of sensory spinal block in patients with rheumatoid arthritis. We decided to test this impression and compared the spread of standard spinal anaesthesia in rheumatoid and non-rheumatoid control patients.

Methods: Spinal anaesthesia with 3.4 ml (17 mg) of plain bupivacaine was administered to 50 patients with seropositive rheumatioid arthritis and to 50 non-rheumatoid control patients. The protocol was standardised for all patients. All the patients were undergoing lower limb surgery and the rheumatoid patients were operated on due to their rheumatoid disease. The spread of sensory block was recorded 30 min from the dural puncture using a pin prick test and a cold ice-filled container. The impact of body mass index (BMI), height and age on the spread were analysed.

Results: The spread of sensory block was greater in patients with rheumatoid arthritis (15.6+/-3.1 dermatomes) than in non-rheumatoid patients (14.1+/-3.3 dermatomes) (P<0.05). Increasing BMI was related to cephalad spread of block in the rheumatoid group (P<0.05), but not in the control group.

Conclusion: The mean spread of sensory block 30 min after the injection of plain bupivacaine was 1.5 segments cephalad in patients with rheumatoid arthritis than in those without this disease. BMI might be a patient-related factor contributing to the extent of the block in rheumatoid patients. These findings should be considered when performing a spinal block in rheumatoid patients.