Invited Editorial: The Role of Volume Expansion in Clinical Management of Hypertensive Pregnant Women

Plasma volume expansion for treatment of women with pre-eclampsia

BACKGROUND

Plasma volume is reduced amongst women with pre-eclampsia. This association has led to the suggestion that expanding the plasma volume might improve maternal and uteroplacental circulation, and so potentially improve outcome for both the woman and her baby.

OBJECTIVES

The aim of this review was to assess the effects of plasma volume expansion for the treatment of women with pre-eclampsia.

SEARCH STRATEGY

The register of trials maintained by the Cochrane Pregnancy and Childbirth Group, and the Cochrane Controlled Trials Register Issue 1 1999 were searched for trials meeting the selection criteria.

SELECTION CRITERIA

Randomised trials were included. Quasi-random designs were excluded. Participants were women with hypertension during pregnancy, with or without proteinuria. Women who were postpartum at trial entry were excluded. Interventions were any comparison of plasma volume expansion with no expansion, or of one plasma volume expander with another.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two reviewers. Discrepancies were resolved by discussion. There was no blinding of authorship or results.

MAIN RESULTS

Three trials involving 61 women were included in this review. All compared a colloid solution with no plasma volume expansion. For every outcome reported, the confidence intervals are very wide and cross the no effect line.

REVIEWER'S CONCLUSIONS

There is insufficient evidence for any reliable estimates of the effects of plasma volume expansion for women with pre-eclampsia.

Pre-eclampsia: the effect of intravenous fluid preload on atrial natriuretic peptide secretion during caesarean section under spinal anaesthesia

BACKGROUND

The haemodynamic effect of volume load at elective Caesarean delivery may be modulated by atrial natriuretic peptide (ANP) especially in pre-eclamptic women in whom basal ANP levels are increased.

METHODS

We followed the haemodynamic parameters and determined the peripheral venous levels of ANP before and after an intravenous volume preload of 1000 ml of Ringer's acetate solution, followed by a further load of the same volume under spinal anaesthesia in 7 healthy and in 6 pre-eclamptic women.

RESULTS

During the preload period the median ANP level increased more (from 14.8 to 22.1 pmol/l, P = 0.03) in pre-eclamptic than in healthy women (from 8.0 to 8.5 pmol/l, NS); while an increment in central venous pressure (CVP) was also greater in pre-eclamptic than in healthy women. The increase in the concentrations of ANP correlated significantly (P < 0.05) with the increase in CVP in the total study group. A significant increase in ANP levels in healthy pregnant women was not seen until during the second infusion period under spinal anaesthesia; in pre-eclamptic women the levels increased further during that period.

CONCLUSION

These findings concur with the theory that atrial stretch is a stimulus for ANP release. An exaggerated release of ANP in response to volume loading may aid in the adaptation of maternal circulation to volume load at elective Caesarean delivery in pre-eclamptic women.