Peripheral nerve stimulator-induced electrostimulation at the P6 point reduces the incidence of post-spinal hypotension in patients undergoing post-trauma orthopaedic surgery

Objectives: Sympathetic block following spinal anaesthesia is often associated with a fall in blood pressure. This fall has been shown to be attenuated by using transcutaneous nerve stimulation at the P6 point in patients receiving spinal anaesthesia for Caesarean section. The aim of this study was to evaluate the efficacy of stimulation at the P6 point, using peripheral nerve stimulator (PNS), for the prevention of a fall in blood pressure in trauma patients undergoing surgery under spinal anaesthesia. Design: Randomised, open-label, parallel-assignment, interventional trial. Setting and subjects: Thirty-two American Society of Anesthesiologists I and II young adult patients of either sex, who were scheduled for elective post-trauma lower limb orthopaedic surgery under spinal anaesthesia, were randomised into two equal groups. The control group (group A) received no P6 stimulation, while the study group (group B) received train-of-four electrical stimulation using the peripheral nerve stimulator (PNS) immediately prior to spinal anaesthesia until the completion of surgery. Outcome measures: The primary outcome measure was mean arterial pressure (MAP) and the secondary outcome measure was heart rate and use of vasopressors. Results: Of the 32 patients, there was a fall in mean arterial pressure (MAP) from basal value following spinal anaesthesia in 16 patients receiving P6 stimulation (group B), as well as in those not receiving it (group A). However, the onset of significant fall in MAP was not only delayed (20 minutes vs. 10 minutes), but was also of shorter duration (10 minutes vs. 50 minutes), in group B patients, than it was in patients in the non-stimulated group (group A), respectively. Conclusion: Electrostimulation by PNS of the P6 point successfully attenuates the severity and duration of hypotension after spinal anaesthesia during post-trauma orthopaedic surgery.