Hypotension from spinal anesthesia in patients aged greater than 80 years is due to a decrease in systemic vascular resistance
Journal of Clinical Anesthesia, 05/07/2012
Nakasuji M et al. – A decrease in systemic vascular resistance (SVR), not cardiac output (CO), is the main mechanism of hypotension seen during spinal anesthesia in elderly patients.
Records from 60 consecutive patients over 80years of age, who underwent hip fracture repair (intramedullary nail or compression hip screw) during spinal anesthesia were studied.
After injection of isobaric 0.5% bupivacaine in the L3-L4 intervertebral space in the lateral decubitus position, patients were turned supine.
Acetate Ringer’s solution (300mL) was infused over 30minutes after subarachnoid puncture.
A decrease in systolic arterial pressure to less than 100mmHg was treated with an intravenous injection of 5mg ephedrine.
The hypotension group (n=18) comprised patients who required ephedrine during the 30 minutes after the puncture, and the nonhypotension group (n=42) consisted of patients who maintained stable arterial pressure with crystalloid infusion only.
Cardiac output (CO) and stroke volume variation (SVV) every 20seconds using the Vigileo-FloTrac system continuously from arrival in the operating room (OR) to 30minutes after the subarachnoid puncture were recorded.
Serial changes in systemic vascular resistance (SVR), CO, and SVV from baseline after puncture were compared between the two groups.
The decrease in SVR over 20minutes after the puncture was significantly greater in the hypotension group than the nonhypotension group (P=0.047).
Cardiac output was stable in the two groups.
Stroke volume variation in the first 10minutes after the puncture increased to similar levels in the two groups, then decreased gradually to baseline.
No significant differences were noted in circulatory parameters on arrival at the OR.
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