Spinal Anesthesia and Hypotension: Mechanisms, Risk Factors, Prophylaxis and Correction

Hypotension is the most common adverse effect of spinal anesthesia (SA). The insidence of SA-induced hypotension in the total population is 15-33%, in patients of older age groups it reaches 80%. At young and middle ages, the main determinant of SA-induced hypotension is considered to be a reduction of postload and venous reflux, due to blood deposition in capacitance vessels of the lower extremities. The aortocaval compressionsyndromeplays a significant role in obstetric practice, cardiac output does not change. In elderly patients, the main prerequisite for the development of hypotension is an enhanced basal sympathetic toneon the background of SA. In patients of this category, in addition to reducing the total peripheral vascular resistance (TPVR), a decline in cardiac output also plays a role. Risk factors for anesthesia-induced hypotension are the followings: (chronic alcohol consumption, history of hypertension, sensory block upper than Th6, and urgency of surgery). To prevent SA-induced hypotension it is advisable to reduce the doses of local anesthetics. Data from the most studies do not confirm the effectiveness of extended infusion therapy in the prevention and correction of hypotension. Vasopressors - phenylephrine in obstetric practice, ephedrine or dopamine in elderly patients are effectiveforpreventinghypotension.