Crystalloid/colloid versus crystalloid intravascular volume administration before spinal anesthesia in elderly patients: the influence on cardiac output and stroke volume.

Abstract

Hypotension is the most common cardiovascular response to spinal anesthesia. We compared the effects of crystalloid/colloid versus crystalloid administration before spinal anesthesia on cardiac output (CO) in elderly patients undergoing transurethral resection of the prostate. Sixty male ASA I-III patients were randomized to one of three groups the control group received no intravascular volume preload, the saline group received 500 mL saline, and the hydroxyethyl starch (HES) group received 500 mL of saline plus 500 mL of 6% HES 130/0.4 within 20 min before spinal anesthesia. Mean arterial blood pressure (MAP) and heart rate, CO, and stroke volume were recorded with a thoracic electrical bioimpedance device. MAP significantly decreased from baseline in the control group (from 104 +/- 20 mm Hg to 88 +/- 11 mm Hg [P = 0.005]) and was significantly lower than in the HES group (from 107 +/- 13 mm Hg to 97 +/- 12 mm Hg [P = 0.001]). In the saline group, MAP decreased (103 +/- 14 mm Hg to 92 +/- 17 mm Hg) with no significant differences compared with the control and HES groups. CO decreased significantly in the control group (from 4.9 +/- 1.6 L/min to 3.8 +/- 0.9 L/min [P = 0.002]) and was significantly lower than in the HES patients in whom CO increased significantly after volume preload (from 5.2 +/- 1.23 L/min to 6.2 +/- 1.43 L/min [P = 0.003]) and remained at baseline level until the end of the study. Intravascular volume preload with saline plus HES prevented a decrease of CO, but did not prevent spinal anesthesia-induced hypotension in elderly patients undergoing transurethral resection of the prostate.