Measurement of Hemodynamic Variables Under Spinal Anesthesia With Varied Positioning

Overview

Multiple studies have compared spinal anesthetic performed supine versus lateral, with varying results, in parturients having elective cesarean section. Needle positioning during spinal placement has also been examined. No positioning techniques have demonstrated definitive superiority for hemodynamic stability. Investigators propose that following spinal placement in the sitting position if the patient is placed in a lateral position for 90 seconds prior to turning them supine, hemodynamic changes caused by sympathectomy related to the subarachnoid block can be avoided. This is the first study to examining the influence of position changes after spinal anesthetic placement in the sitting position, which includes hemodynamic variables not previously studied including cardiac output, TPR (total peripheral resistance) and pulse pressure variation (PPV).

Cesarean section is chosen when natural spontaneous vaginal delivery is either not possible or when the health of the baby or mother is compromised. Cesarean section may be planned, urgent, or performed emergently when the life of the baby or mother is threatened. Cesarean section is performed using different anesthetic techniques including: spinal, epidural, combined spinal and epidural, and general anesthesia. Spinal anesthesia is the most common technique chosen due to its relative safety, rapid onset and avoidance of potential complications from general anesthesia. It is the technique of choice for elective cesarean section unless contraindicated. Spinal anesthesia causes sympathetic blockade followed by sensory and motor blockade. Nerve fiber size explains the speed of onset and differential block. The critical moments during spinal anesthesia come as soon as local anesthetic is injected into the subarachnoid space.