Preoperative Oral Midodrine for Prophylaxis Against Post Spinal Hypotension in Knee Arthroscopic Surgeries: A Randomized Clinical Study

Abstract

Background: Midodrine has been utilized efficiently for prophylaxis against several hypotensive syndromes like weaning cases off the intravenous vasopressors, orthostatic hypotension and reducing the frequency of hypotension happening throughout dialysis.

Objective: Our aim was to assess the efficiency of oral midodrine as a prophylaxis against hypotension following spinal anesthesia in cases having knee arthroscopy.

Methods: This randomized double blinded controlled study has been carried out on 100 patients aged 21 to 45 years of either gender having elective knee arthroscopy under spinal anesthesia. Cases have been randomized to midodrine group (administered ten milligrams pills of midodrine) or placebo (control) group (administered placebo pills), and pills have been given 75 minutes prior to spinal anesthesia (intrathecal injection of 12.5 milligrams 0.5 percent hyperbaric bupivacaine and 25 milligrams fentanyl). The 1^ry result was the prevalence of hypotension, identified as a systolic blood pressure below ninety millimeter Hg or below eighty percent of baseline. 2^ry results were hemodynamic features (heart rate (HR) and mean arterial pressure (MAP)) following spinal anesthesia, ephedrine or atropine doses, and the prevalence of complications involving vasovagal attacks, bradycardia, reactive hypertension vomiting, nausea, in addition to shivering.

Results: Baseline hemodynamic features were similar among the 2 groups. In the midodrine group, 25 (50%) cases had hypotension following spinal anesthesia against 43 cases (86%) in the placebo group. The median intraoperative (quartile) overall dose of ephedrine was significantly reduced in midodrine group 12 (0-27) milligrams compared to placebo group 36 (21-45) milligrams, P-value: 0.001). The frequency of bradycardia in addition to hypertension were similar among the 2 groups. Moreover, the MAP and HR were similar among the 2 groups. In the two groups, the MAP during surgery reduced in association with the baseline reading, whereas the HR has been generally sustained.

Conclusions: preoperative administration of oral midodrine ten milligrams tablets prior to spinal anesthesia is an efficient technique in the avoidance of post-spinal hypotension in adult cases having elective knee arthroscopic surgeries.