Nisell H, Hjemdahl P, Linde B, Lunell N O
Am J Obstet Gynecol. 1985 Jul 1;152(5):554-60. doi: 10.1016/0002-9378(85)90623-4.
Sympathoadrenal and cardiovascular responses to tilting were studied in patients with pregnancy-induced hypertension and healthy control subjects during the last trimester of pregnancy and 8 to 12 weeks post partum. Blood volumes were lower in the patients with pregnancy-induced hypertension during pregnancy (0.065 versus 0.081 L/kg, p less than 0.01) but not post partum. Tilting induced significantly smaller increases in heart rate and arterial plasma norepinephrine concentrations and smaller changes in blood pressure during pregnancy as compared to after pregnancy in both groups. Forearm vascular resistance increased significantly in both groups after pregnancy but only in the patients with pregnancy-induced hypertension during pregnancy. The forearm vasoconstrictor response to tilting was, in fact, totally abolished in the third trimester of normal pregnancy. The hypertensive patients had higher arterial plasma epinephrine levels at rest and greater epinephrine and norepinephrine responses to tilting than the control subjects during pregnancy. Normal pregnancy appears to reduce the circulatory and sympathoadrenal responses to orthostatic stress, presumably because of volume expansion that allows venous return to be better maintained in the upright position. The less pronounced pregnancy-induced increase in blood volume in patients with pregnancy-induced hypertension appears to explain the increased sympathoadrenal and forearm vascular reactivity in this group during pregnancy.
在妊娠晚期及产后8至12周，对妊娠高血压患者和健康对照者进行了倾斜试验，以研究交感肾上腺和心血管系统的反应。妊娠高血压患者孕期血容量较低（0.065对0.081 L/kg，p<0.01），但产后无差异。与产后相比，两组在孕期倾斜试验引起的心率和动脉血浆去甲肾上腺素浓度升高明显较小，血压变化也较小。两组产后前臂血管阻力均显著增加，但仅妊娠高血压患者在孕期增加。事实上，正常妊娠晚期前臂对倾斜试验的血管收缩反应完全消失。孕期高血压患者静息时动脉血浆肾上腺素水平较高，对倾斜试验的肾上腺素和去甲肾上腺素反应比对照组更强烈。正常妊娠似乎会降低对直立位应激的循环和交感肾上腺反应，这可能是由于血容量增加，使直立位时静脉回流得以更好维持。妊娠高血压患者孕期血容量增加不明显，这似乎解释了该组在孕期交感肾上腺和前臂血管反应性增加的原因。
