Hypotension following spinal anesthesia in obstetric patients is a common complication with incidence as high as 80 percent. Unless urgently treated, it might lead to fetal hypoxic stress and acidosis due to reduced uteroplacental blood flow and reduced cardiac output in mother with catastrophic effects on both mother and fetus.^.

Vasopressors are the mainstay in the management of hypotension associated with spinal anesthesia. Commonly used vasopressors are Ephedrine, Mephenteramine and phenylephrine with different benefits. Phenylephrine, a pure alpha agonist is the first line vasopressor in treatment of hypotension in normotensive patients , both as bolus and infusion. Phenylephrine boluses in dose range of 50-100µg have been used in both normotensive and pre eclamptic patients but the optimum dose is not yet proved. High doses are reported to cause maternal hypertension, bradycardia and decrease in cardiac output whereas lower dose may be associated with repeated dosing . Compared to healthy patients, the dose requirement of phenylephrine in pre eclamptic patients is expected to be lower due to smaller fetus and diffuse endothelial dysfunction with decreased synthesis of vasodilators but increased sensitivity of vasoconstrictors .

There is inadequate literature on the effective dose of phenylephrine as bolus injection in preeclampsia patients to treat post spinal hypotension. Hence, we intend to study two different doses of phenylephrine bolus injections in treatment of post spinal hypotension in Pre-eclampsia patients undergoing LSCS.