A regression model for identifying patients at high risk of hypotension, bradycardia and nausea during spinal anesthesia.

We analyzed the predictive value of a number of demographic and anesthesiological variables with respect to the three most common complications during spinal anesthesia: hypotension, bradycardia, and nausea. A stepwise logistic regression model was created, using data from a prospective study of 1752 patients to combine the predictive value of all entry variables. The highest risk factors for hypotension were: age greater than or equal to 50, a sensory level above Th6, receiving bupivacaine as a local anesthetic, body mass index greater than or equal to 30, and receiving opiate as a premedication. An anesthetic level above Th6 and age below 50 were primarily associated with bradycardia. Females and those with a high sensory level or receiving opiate as a premedication were at significant risk of nausea. The model was also reliably predictive for a separate group of 200 consecutive spinal anesthesia patients. Thus, the risk model may be clinically useful in identifying high-risk patients requiring additional attention.