Comparison of the Effects of Milrinone, Sodium Nitroprusside, and Nitroglycerine for Induced Hypotension in Elderly Patients Undergoing Spine Surgery: A Randomized Controlled Trial

Background:The use of induced hypotension is limited because of concerns about hypoperfusion to major organs in elderly patients. The aim of this study was to compare the effects of milrinone with those of other vasodilating hypotensive agents on induced hypotension in elderly patients undergoing spine surgery.Methods:In total, 60 patients older than 60 years who underwent lumbar fusion surgeries were randomized to groups M (milrinone), S (sodium nitroprusside), and N (nitroglycerine). The study drug was infused after perivertebral muscle retraction until complete interbody fusion occurred. The infusion dose was adjusted to achieve a fall of 30% in systolic blood pressure or mean blood pressure to 60 to 65 mm Hg. Intraoperative blood loss, grade of the surgical field, and urine output were recorded.Results:Intraoperative blood loss per fused spine level was 288.5±94.4 mL in group M, 399.8±60.3 mL in group S, and 367.0±122.5 mL in group N (P=0.002). The grade of the surgical field was similar among the 3 groups (P=0.439). Hourly urine output was 1.4±0.5 mL in group M, 0.7±0.3 mL in group S, and 0.9±0.4 mL in group N (P<0.001).Conclusions:The use of milrinone for induced hypotension led to less intraoperative blood loss and higher urine output than the use of sodium nitroprusside or nitroglycerine in elderly patients undergoing spine surgery.