Intravenous Volume Expansion Therapy in Pregnancy-Induced Hypertension: The Role of Vasoactive Hormones

Objective: To examine the hormonal and clinical effects of intravenous volume expansion therapy in women with pregnancy-induced hypertension (PIH).Methods: Fifteen untreated women with PIH, six of whom had significant proteinuria, were randomized to receive a 500 ml infusion of either Haemaccel (n = 7) or a control solution (hypotonic saline, n = 8), and the acute response of the following hormones was examined: plasma atrial natriuretic peptide (ANP), angiotensin II (ANG II), adrenaline (Adr), and noradrenaline (NA). These were measured by radiomimmunoassay or enzyme immunoassay as appropriate following plasma extraction. Blood pressure (BP) and pulse rate (PR) were measured before, during, and after the infusion as well as 24 and 48 h later.Results: The infusion of Haemaccel but not hypotonic saline was associated with a significant decrease in plasma albumin and hematocrit. Plasma ANP increased significantly in those who received Haemaccel but not in controls, while there were no significant changes in plasma ANG II, Adr, or NA in response to either infusion. There were no acute changes in blood pressure or pulse rate in response to intravenous volume expansion.Conclusions: Intravenous volume expansion therapy in women with PIH is associated with an increase in plasma ANP which does not acutely decrease blood pressure but may have a role in the more chronic effects of such treatment.