Effect of Ondansetron on Spinal-induced Hypotension for Percutaneous Nephrolithotomy
Status:
Recruiting
Trial end date:
2021-12-31
Target enrollment:
Participant gender:
Summary
Percutaneous nephrolithotomy (PCNL) is the surgical standard for treating large or complex
renal stones. The stones are removed by passing a small telescope through the side of the
patient directly into the kidney, so the stone can be broken up and the fragments are removed
.PCNL can be performed under general anesthesia or spinal anesthesia. SA has some advantage
over GA, such as lower postoperative pain, lower consumption of analgesic drugs and avoidance
of side effects from multiple medications used in GA.However, SA induced sympathetic block
leads to a decrease in the systemic vascular resistance and subsequent drop in the arterial
blood pressure. Furthermore, anesthesia for PCNL usually requires a high sensory level
reaching T4,resulting in a high incidence (nearly 33%) of hypotension. Also, to meet the long
duration of surgery, drugs, ;like dexmedetomidine, are added to intrathecal local anesthetics
, increasing the incidence of hemodynamic instability induced by the spinal anesthesia.
Decreasing the systemic vascular resistance (SVR) and the venous return to the heart result
in a reflex vasodilation, bradycardia and hypotension. This reflex is called Bezold -Jarisch
reflex and is mediated by serotonin receptors (5_HT3) located on the vagus nerve and within
the wall of the cardiac ventricles.
Ondansetron; an antiemetic drug used for treatment of perioperative nausea and vomiting, was
investigated as a 5HT antagonist for inhibition of Bezold - Jarisch reflex. While some
studies proved its efficacy in prevention of spinal anesthesia induced hypotension , other
studies could not support this conclusion .