Article Text
PDF
Abstract
Please confirm that an ethics committee approval has been applied for or granted: Yes: I’m uploading the Ethics Committee Approval as a PDF file with this abstract submission
Background and Aims Ropivacaine has become more popular for spinal anesthesia due to a shorter duration of blockade than bupivacaine. We investigated the correlation between patient height, intrathecal ropivacaine dose, and block duration.
Methods Retrospective study of adults receiving ropivacaine spinal anesthesia for elective total hip arthroplasty at one institution between 1/1/2000, and 12/31/2023. Collected variables included ropivacaine dose, patient height, time to full motor recovery by the modified Bromage scale, weight, age, and the use of IV dexamethasone and dexmedetomidine.
Results Out of 2063 records, 2034 had full data. Ropivacaine dose was 13.5 ± 1.9 [range 6 to 20 mg] and duration was 225.3 ± 62.0 [range 98 to 575 min]. Scatter plots as well as Pearson and Spearman correlation tests demonstrated weak positive correlations between duration, height and dose. There was also a weak correlation (0.21) between height and dose, suggesting that some anesthesiologists might adjust the dose based on weight. Multiple linear regression yielded a small R2 value (0.047), suggesting that dose and height explain only in small part the variability in duration.
Scatterplot of block duration vs. patient height
Scatterplot of block duration vs. ropivacaine dose
Conclusions There is a weak positive correlation between ropivacaine spinal dose and duration of motor blockade, while patient height has almost no correlation with motor block duration. Within the range of clinically used doses, most of the variability in duration appears related to the factors outside of the ropivacaine dose and patient height.