Comparing the different dosages of prophylactic phenylephrine infusion effect on hypotension in elderly patients under spinal anesthesia in orthopedic surgeries

The purpose of this study will be to assess the effect ofdifferent dosages of prophylactic phenylephrine infusion effect on hypotension in elderly patients under spinal anesthesia in orthopedic surgeries

Clinical trial with two arm parallel groups, randomised trial with double blinded assessment. Study phase will be 2-3.

In Urmia Imam Khomeini hospital operating room the patients under spinal anesthesia in orthopedic surgeries will be divided into two parallel groups (30 patients each group). The drug will be administered by the nurse , the anesthesiologist will be unaware which patient will be assigned to which group. Drug containers will be identical and only the nurse will know about the contents of each of them, and finally, after collecting information by the resident in training in anesthesiology, the anesthesiology specialist will be informed of the group each patient is assigned to. Hemodynamic changes during surgery will be compared.

Inclusion criteria : over 60 years, American Society of Anesthesiologists physical status classification I and II, Patients under spinal anesthesiaAges 1 to 60 Exclusion criteria:Heart rate less than 45, Drug sensitivity to local anesthetics, Existence of uncontrolled systemic diseases such as diabetes or high blood pressure, Heart disease such as heart failure or arrhythmias, History of neurological or psychological diseases, Existence of any contraindications to performing spinal anesthesia

Intervention group(A):Phenylephrine will be injected intravenously in 10 cc syringes containing 10 mg / ml in 100 ml of normal saline and Intervention group(B):Phenylephrine will be injected intravenously in 10 cc syringes containing 10 mg / ml in 200 ml of normal saline immediately after changing position to supine position

Mean blood pressure

The number of patients in this study will be 60. This number of patients will be exclusive randomly assigned into two groups of phenylephrine 10mg / ml in 100 ml of normal saline(group A) and phenylephrine 10mg / ml in 200 ml of normal saline (group B) using Random Allocation Software 2.0, and the target codes will be written and placed in sealed envelopes with sequential allocation using double-blind method.

The anesthesiologist will be unaware of which patient will be assigned to which group. phenylephrine syringes will be identical and only the operating room will knew about the contents of each of them, and finally, after collecting information from the anesthesia residents, the anesthesiologist will be informed of the group each patient will be assigned to.