Dose-to-block Level Relation in Single Shot Spinal Anesthesia for Cesarean Section.

Overview

The study is designed to support or deny relation between the dose of hyperbaric bupivacaine given intrathecally and extent of spinal block level. There is ongoing debate whether anesthetists should adjust the dose in the range of conventional doses in order to achieve appropriate coverage of anesthesia which would be suitable for cesarean section. Two strategies are predominantly used: low dose strategy, which is focused on safety, and conventional dose approach, which is more effective in terms of success of anesthesia, with markedly higher rate of spinal block - related complications. It is hypothesized that there may be no relation between block level and the dose if conventional doses are used. For that purpose anesthetic charts of cesarean sections will be reviewed to gather information on the doses of anesthetic used and the level of spinal block they produced.

Single - shot spinal block for cesarean delivery is a gold standard in obstetric anesthesia. Both level and density of the block may have direct impact on the quality of surgery, patient's comfort and the course of postoperative recovery. Ideal dose of local anaesthetic for single - shot spinal anesthesia is still to be decided, with ongoing debate on using either "low" or "conventional" doses as routine approach. Use of conventional doses of local anesthetic (doses nearing dose effective in 95 percent of patients,ED95) have proven to be superior to low dose regimens in terms of effectiveness and therefore this strategy is widely used, despite the higher risk of spinal block - related complications. Amount of local anesthestic used is regarded to be a factor of significant influence on its intrathecal spread and the final level of block following single - shot spinal anesthesia. It was investigated in both general and obstetric populations, although most of the studies with results in favor of this relation were designed to assess the other factors, and the extend of sensory block was not set as their primary outcome. It was previously reported that adjusting the conventional dose of hyperbaric bupivacaine to parturient's height does not change the risk of block failure and rate of complications when compared to fixed - dose regimen. Whether the change in bupivacaine dose within the range of conventional doses results in significant change in sensory block level is not clear. This retrospective analysis was designed to assess the above relation