BACKGROUND: Spinal anaesthesia-induced maternal hypotension is common during elective caesarean section. This study evaluated whether cerebral near-infrared spectroscopy predicts maternal hypotension, defined as a 25% reduction in systolic blood pressure or heart rate or presentation of clinical symptoms. METHOD: Thirty-eight ASA I-II parturients scheduled for elective caesarean section with spinal anaesthesia were monitored by near-infrared spectroscopy for changes in cerebral oxygenation (ScO(2)) with the recordings blinded to the anaesthesiologist. RESULTS: There was a 5% decrease in ScO(2) (median 8%, interquartile range 5-11%) in all 22 patients who developed hypotension, whereas only 2 of 13 women who did not develop hypotension had a 5% decrease in ScO(2). Median time from a 5% decrease in ScO(2) to hypotension was 81 (interquartile range 30-281) s. The sensitivity of near-infrared spectroscopy to predict hypotension was 1.00, with a specificity 0.85 and a predictability of 0.91. CONCLUSION: The results demonstrate a relationship between ScO(2) and impending hypotension during low-dose spinal anaesthesia for elective caesarean section. We suggest that immediate measures are taken to stabilise blood pressure if the near-infrared spectroscopy determined cerebral oxygenation decreases by more than 5%.
International Journal of Obstetric Anesthesia, 2005, Vol 14, Issue 1, p. 26-31