The effect of thigh-length support stockings on the hemodynamic response to ambulation in pregnancy.

Abstract

Our purpose was to determine the effect of thigh-length support stockings on hemodynamic response when pregnant subjects change from the sitting to the lateral recumbent position and then after standing with ambulation. Eighteen subjects in the late second and early third trimester of pregnancy acted as their own controls. The cardiovascular status of the subjects was assessed by a noninvasive technique--thoracic electrical bioimpedance before and after wearing support stockings for 1 week. Urine catecholamines were measured in 13 patients before and after wearing support stocking to assess the release of catecholamines. Samples were collected after the subjects had been in the lateral recumbent position 40 minutes and again 40 minutes later after standing with ambulation. Heart rate and mean arterial blood pressure decreased significantly when subjects changed from the sitting to the lateral recumbent position and then increased with ambulation. Wearing compression stockings significantly increased mean arterial pressure and afterload in all three positions. Position change from lateral recumbent to standing and ambulation marginally increased urinary dopamine levels (p = 0.097) and significantly increased norepinephrine levels (p = 0.006). There are significant hemodynamic changes in pregnant subjects when they change from the sitting position to the lateral recumbent position and then change to standing with ambulation. Support stocking have a significant mechanical effect: they significantly increase afterload and systemic vascular resistance by preventing pooling of blood in the lower extremities. There may also be a biochemical effect that results in less catecholamine release. These results suggest that compression stockings could play an important role in supporting the circulation during ambulation.