Role of Granisetron in Preventing Hypotension After Spinal Anesthesia With Levobupivacaine in Rheumatic Patients Undergoing Elective Cesarean Section: A Randomized Clinical Trial

The subarachnoid block is the most used anesthesia technique for conducting a cesarean section. The incidence of hypotension following this procedure is as high as 20-40% in pregnant patients. Similarly, bradycardia is also commonly associated with post-SAB, and the reported incidence is around 13%. Spinal anesthesia results in sympathetic block leading to a decrease in systemic vascular resistance and hypotension. Hypotension caused by subarachnoid block is physiologically compensated by an increase in heart rate. However, if vagus nerve-mediated Bezold-Jarisch reflex gets stimulated, then the cardiac autonomic balance gets shifted towards the parasympathetic nervous system leading to bradycardia, which further precipitates hypotension.

Levobupivacaine is a highly potent long-acting local anesthetic with a comparatively slow onset of action. Compared to bupivacaine, it has a lower tendency to block deactivated cardiac sodium and potassium channels with a more rapid rate of dissociation. It has reduced cardiac toxicity on overdose intravenous administration due to its faster protein binding rate. Plain levobupivacaine is isobaric to CSF. One of its advantages is that it has a more expectable spread. Several studies have revealed the reduced occurrence of various side effects (such as nausea, vomiting, bradycardia, and hypotension) when levobupivacaine compared with bupivacaine for spinal anesthesia used for cesarean delivery. It has been suggested to use 12.5-13.5mg levobupivacaine for effective spinal anesthesia for cesarean delivery.