The objective of this study was to determine the effect of volume expansion with colloid on oxygen consumption (VO2), oxygen delivery (DO2) and the oxygen extraction ratio in patients with severe preeclampsia. The study was prospective and descriptive and took place in the tertiary care labor and delivery unit in a university hospital. Fourteen women with severe preeclampsia who received a pulmonary artery catheter and radial arterial line to monitor their hemodynamic and respiratory status took part in the study. Patients who had received prior medication or volume expansion were excluded. The intervention employed was acute volume expansion, using colloidal solutions (Dextran 70 or Haemaccel) to elevate the pulmonary capillary wedge pressure (PCWP) > 12 mm Hg, and this was followed by repeat measurements. The main outcome measures were PCWP, mean pulmonary artery pressure, cardiac output, systemic vascular resistance, VO2, DO2, and oxygen extraction. The VO2 and DO2 (but not oxygen extraction) increased proportionately to cardiac index, and inversely with afterload, but had no significant relationship with preload or volume of colloid infused. The oxygen extraction ratio remained abnormally low despite improved perfusion. There was no relationship between change in preload and the volume of colloid infused. Mean pulmonary artery pressure was a better indicator of preload than was wedge pressure. Volume expansion, associated with an increase in cardiac index and a reduction in afterload, increases VO2 and DO2 in preeclampsia. Oxygen extraction remains unchanged and VO2 is DO2 dependent. An increase in preload may be required to maintain cardiac index during afterload reduction, but does not appear to have any direct effect on VO2.
- Oxygen consumption
- Volume expansion
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health
- Obstetrics and Gynecology