Distribution and elimination of crystalloid fluid in pre-eclampsia

Pre-eclampsia (PE) is a disease of pregnancy associated with peripheral oedema and hypovolaemia, but few details are known about how women with PE handle a volume load of crystalloid fluid compared with healthy pregnant women. To study this issue, Ringer's acetate solution (12.5 ml/kg of body weight) was given by intravenous infusion over 30 min to eight women with PE and to eight healthy pregnant women matched with respect to gestational week (mean, 34 weeks). Venous blood was sampled and excreted urine was collected over 90 min to study the time course of the volume expansion by means of volume kinetic analysis. The results show that the size of the central body fluid space expanded by the infused fluid was smaller in PE (mean, 2940 ml compared with 4240 ml respectively; P<0.04), and the clearance constants for distribution (100 ml/min compared with 43 ml/min; P<0.04) and elimination (125 ml/min compared with 36 ml/min; P<0.02) were higher in the women with PE than in the controls. Less excess volume accumulated in the central body fluid space in the presence of PE, whereas the rates of distribution and elimination were higher during and for 15 min after the infusion. It is concluded that Ringer's acetate solution fluid is both distributed and eliminated faster in women with PE than in matched pregnant controls.

Volume Kinetics of Intravenous Fluid Therapy in the Prehospital Setting

Introduction:To study the volume effect of isotonic and hypertonic crystalloid fluid during ambulance transports after mild trauma, a prospective case-control study was initiated, using the ambulance and helicopter transport system in Stockholm.Methods:The hemodilution resulting from intravenous infusion of 1.0 L of Ringer's acetate solution (n = 7) or 250 ml of 7.5% sodium chloride (n = 3) over 30 minutes (min) was measured every 10 min during 1 hour when fluid therapy was instituted at the scene of an accident, or on arrival at the hospital. The dilution was studied by volume kinetic analysis and compared to that of matched, healthy controls who received the same fluid in hospital.Result:The hemodilution at the end of the infusions averaged 7.7% in the trauma patients and 9.1% in the controls, but the dilution was better maintained after trauma. The kinetic analysis showed that the size of the body fluid space expanded by Ringer's solution was 4.6 L and 3.8 L for the trauma and the control patients, respectively, while hypertonic saline expanded a slightly larger space. For both fluids, trauma reduced the elimination rate constant by approximately 30%.Conclusion:Mild trauma prolonged the intravascular persistence of isotonic and hypertonic crystalloid fluid as compared to a control group.

Volume Kinetics of Ringer's Solution in Hypovolemic Volunteers

Background The amount of Ringer's solution needed to restore normal blood volumes is thought to be three to five times the volume of blood lost. This therapy can be optimized by using a kinetic model that takes accounts for the rates of distribution and elimination of the infused fluid. Methods The authors infused 25 ml/kg Ringer's acetate solution into 10 male volunteers who were 23 to 33 yr old (mean, 28 yr) when they were normovolemic and after 450 ml and 900 ml blood had been withdrawn. One-volume and two-volume kinetic models were fitted to the dilution of the total venous hemoglobin and plasma albumin concentrations. Results Withdrawal of blood resulted in a progressive upward shift of the dilution-time curves of both markers. The two-volume model was statistically justified in 56 of the 60 analyzed data sets. The hemoglobin changes indicated that the body fluid space expanded by the infused fluid had a mean total volume of 10.7 l(+/-0.9 SEM). The elimination rate constant (kr) decreased with the degree of hypovolemia and was 133 ml/min (22 ml/min [SEM]), 100 ml/min (39 ml/min [SEM]), and 34 ml/min (7 ml/min [SEM]), respectively (P &lt; 0.01). Plasma albumin indicated a slightly larger body fluid space expanded by the infused fluid, but kr was less (P &lt; 0.02). Hypovolemia reduced the systolic and diastolic blood pressures by approximately 10 mmHg (P &lt; 0.05). Conclusions The dilution of the blood and the retention of infused Ringer's solution in the body increases in the presence of hypovolemia, which can be attributed chiefly to a reduction of the elimination rate constant.