[Spinal anesthesia in high-volume, low-concentration technique for Caesarean sections : Retrospective analysis]

Nowadays Caesarean sections are mainly undertaken using spinal anesthesia; therefore, it is important to minimize potential side effects and risks associated with this technique. Currently, many studies have been conducted to optimize the dose of local anesthetics to avoid hypotension, which often occurs during spinal anesthesia.

In a retrospective study design the high-volume, low-concentration technique with up to 12 ml isobaric bupivacain 0.1% (1 mg/ml) and sufentanil (1 µg/ml), which has been used at the University Hospital Würzburg for many years was analyzed with respect to reliability and side effects. The use of this technique so far is unique among university hospitals in Germany.

Of the 1424 anesthesia protocols from 2001 to 2007 a total of 1368 were analyzed. Demographic data and parameters, such as location of puncture, dose and extent of anesthesia, hemodynamic stability and additional medication were recorded. A decrease of systolic blood pressure of more than 20% of the initial value was defined as hypotension.

The median volume used for spinal anesthesia was 9 ml, containing 9 mg bupivacaine and 9 µg sufentanil. The rate of hypotension was 48.8 %. No significant differences in hypotension between lower and higher volumes were detectable. In 0.84% (n=12) of the cases the procedure had to be changed to general anesthesia and additional analgesia was administered in 3 cases (0.22%).

The high-volume, low-concentration technique is an effective approach for spinal anesthesia with a small number of cases needing general anesthesia or additional analgesics. The rate of hypotension was moderate compared to other studies; however, because of the retrospective and non-randomized study design the dependence of this rate on dose and given volume should be interpreted with caution.