Risk factors for supine hypotension syndrome after spinal anesthesia in parturients

Objective To identity the risk factors for supine hypotension syndrome (SHS) after spinal anesthesia in parturients. Methods A total of 204 parturients, scheduled for elective cesarean section, were divided into either control group or SHS group depending on whether or not SHS (systolic blood pressure [SBP] in the upper extremity decreased by > 30 mmHg or decreased to < 80 mmHg) developed after spinal anesthesia.The baseline patient characteristics such as age, body height and weight, gestational weeks and biparietal diameter were recorded.Supine stress test (SST) was performed.Heart rate, blood pressure in upper and lower extremities, perfusion index, pleth variability index and intravesical pressure were recorded when patients were in supine position and in left lateral position before spinal anesthesia.The risk factors of which P values were less than 0.05 would enter the multi-factor logistic regression analysis to stratify the risk factors for SHS. Results Among the 204 patients, 99 cases developed SHS after spinal anesthesia, and the incidence was 48.5%.Logistic regression analysis showed that maternal body weight, biparietal diameter, the difference in SBP between upper and lower extremities in supine position, the difference in SBP in upper extremities caused by changing position and positive SST were risk factors for SHS after spinal anesthesia (P<0.05 or 0.01). Conclusion Maternal body weight, biparietal diameter, the difference in SBP between the upper and lower extremities in supine position, the difference in SBP in upper extremities caused by changing position and positive SST are risk factors for SHS after spinal anesthesia in parturients. Key words: Pregnant women; Subarachnoid space; Supine position; Hypotension; Risk factors