A randomized, observer-blind comparison between the Neurotip mounted Neuropen and a disposable plastic neurological wheel for assessing the level of spinal blockade at cesarean section

BackgroundVarious methods are used to assess the height of sensory block to touch under spinal anesthesia for cesarean section. We tested a novel, inexpensive, miniature, user-dependent plastic neurological wheel against the user-independent Neurotip mounted Neuropen.MethodsPatients received either spinal or combined spinal–epidural anesthesia. For each patient assessment, the devices were randomly assigned to one of two independent investigators. The order of device application was randomly permuted. Neither researcher was involved with anesthetic care. At 5-min intervals for 20 min after spinal injection, and again at the end of the operation, the levels of block to loss-of-touch sensation were assessed. While one investigator evaluated the block, the other left the operating room and vice versa. Mixed-effects regression and Bland–Altman analysis were used to weigh agreement between devices.ResultsThe mean difference in level-to-touch was 0.04 (95% CI −0.18, 0.27) dermatome levels. Measurement error standard deviation associated with the Neurotip mounted Neuropen and plastic neurological wheel was 1.36 (95% CI 1.26, 1.41) and 1.33 (95% CI 1.26, 1.46) dermatome levels, respectively. The difference in measurement error standard deviation was −0.03 (95% CI −0.16, 0.24). This evidence excludes the possibility, with 95% confidence, of clinically significant bias or measurement error differences between methods. Occasional wide variances in dermatome level were observed with both instruments at the initial assessment only.ConclusionThe compact plastic neurological wheel is as clinically reliable as the Neurotip mounted Neuropen.