Correlation between gestational age and level of sensory block in spinal anesthesia

Abstract

Background and objectives To identify a specific correlation between progression of gestational age and level of sensory block in spinal anesthesia in patients undergoing cervical cerclage. Methods The medical records of patients who underwent cervical cerclage under spinal anesthesia using hyperbaric bupivacaine between March 2016 and May 2018 were retrospectively reviewed. The primary outcome measure was the correlation between gestational age and sensory block level of spinal anesthesia. Secondary outcomes included the correlations between gestational age and reduction in blood pressure and length of the postanesthesia care unit (PACU) stay. The Pearson correlation test, partial correlation test, and linear regression were used to identify relationships and to adjust for confounding variables. Results Of the 261 cases reviewed, there was a linear and significant correlation between gestational age and sensory block level, reduction in systolic blood pressure during surgery, reduction in systolic blood pressure during PACU, and length of PACU stay, after adjusting for confounding factors (partial correlation coefficient=0.71, p<0.001; 0.27, p<0.001; 0.25, p<0.001; 0.21, p=0.001, respectively). A 1-day increase in gestational age corresponded to an increase of 0.04 dermatomes in sensory block level (95% CI 0.035 to 0.045, p<0.001). Conclusion Results demonstrated that as the gestational age progressed, sensory block level increased, blood pressure was decreased, and length of PACU stay increased after spinal anesthesia. Sensory block increased by 0.28 dermatomes when the pregnancy progressed 1 week. Further controlled prospective studies are needed to support this relationship. Trial registration number NCT0000538.