RESPIRATORY-FUNCTION IN SEVERE GESTATIONAL PROTEINURIC HYPERTENSION - THE EFFECTS OF RAPID VOLUME EXPANSION AND SUBSEQUENT VASODILATATION WITH VERAPAMIL

Objectives - (1) To define the baseline respiratory function in untreated severe gestational proteinuric hypertension (GPH) and (2) to assess the effects of volume expansion with dextran (MW = 70 000 Dalton) and subsequent vasodilatation with the calcium antagonist verapamil on the baseline respiratory function in severe GPH. Design - Prospective descriptive study. Setting - Reproductive Research Unit, Groote Schuur Hospital, Cape Town, South Africa. Subjects - Six women with severe GPH undergoing stabilization and delivery. Interventions - Baseline haemodynamic and respiratory function was assessed using invasive monitoring. Patients then underwent volume expansion to a pulmonary capillary wedge pressure of 16 mmHg with dextran-70, followed by vasodilatation with the calcium antagonist verapamil. Haemodynamic and respiratory variables were measured, before and after both the fluid load and the reduction (20%) in the mean arterial pressure. Main outcome measures - Mean arterial pressure, heart rate, mean pulmonary arterial pressure, pulmonary capillary wedge pressure, central venous pressure, cardiac index, systemic vascular resistance, pulmonary vascular resistance, respiratory rate, blood gases, alveolar arterial oxygen difference, oxygen availability, oxygen consumption, pulmonary shunt fraction. Results - Baseline oxygen availability/delivery and oxygen consumption indices were consistent with severe tissue ischaemia. Volume loading with 400 +/- 114 ml dextran-70 normalized these variables, and subsequent vasodilatation with verapamil did not reduce these indices below the normal limits for pregnancy. Conclusions - These data support the theory that some of the complications of severe GPH may follow organ damage due to prolonged tissue ischaemia. They also support the appropriateness of controlled volume expansion in the management of this condition. We suggest, from these data, that the combination of volume expansion and verapamil vasodilatation lowers the blood pressure without compromising the maternal respiratory function.