Hypotension after spinal anesthesia for cesarean section: identification of risk factors using an anesthesia information management system.

OBJECTIVE: To determine risk factors for developing hypotension after spinal anesthesia for cesarean section to prevent obstetric patients from hypotensive episodes potentially resulting in intrauterine malperfusion and endangering the child. METHODS: The data from 503 women, having received spinal anesthesia for cesarean sections were investigated using online gathered vital signs and specially checked manual entries employing an anesthesia information management system. Blood pressure, heart rate, and oxygen saturation were measured throughout and hypotension was defined as either a drop in mean arterial blood pressure of >20% from baseline value or readings of <90 mmHg systolic arterial blood pressure. Thirty-two variables were studied for association with hypotensive episodes using univariate analysis and logistic regression employing a forward stepwise algorithm to identify independent variables (P < 0.05). RESULTS: Hypotension was found in 284 cases (56.5%). The univariate analysis identified the neonate's weight, mother's age, body mass index, and peak sensory block height associated with hypotension. Body mass index, age and sensory block height were detected as independent factors for hypotension (odds-ratio: 1.61 each). CONCLUSIONS: Knowledge of these risk factors should increase the anesthesiologist's attention to decide for the necessity to employ prophylactic or therapeutic techniques or drugs to prevent the neonate from any risk resulting of hypotension of the mother.