Mean arterial pressure and prediction of pre-eclampsia
BMJ 2008; 336 doi: https://doi.org/10.1136/bmj.39555.518750.80 (Published 15 May 2008) Cite this as: BMJ 2008;336:1079
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In 1983 an Australian friend gave me a copy of his paper concerning blood viscosity in pre-eclampsia, yet in this editorial there is no apparent recognition that changed blood rheology is an important determinant of blood pressure.
A search for "Pre-eclampsia and blood viscosity" in PubMed produced 59 titles of papers from authors in several countries. Although there are a few conflicting reports, the majority found increased blood viscosity in pre-eclamptic women. Some authors noted that low-shear rate viscometry indicated reduced red cell deformability, and one report found that 24 hours of intravenous magnesium therapy increased red cell deformability. A Japanese study obtained beneficial results from dextran infusions.
Increased blood viscosity greatly disrupts kidney function through its effect on filtration pressure, and the adverse effects of the hyperviscous blood of flow in the peritubular plexus and thus on tubular reabsorption. The simplest model is polycythemia where a haematocrit of 62 was associated with a high molecular weight proteinuria. But when the haematocrit was reduced to 45, there was no proteinuria.
It seems that on the basis of the published information the treatment of pre-eclampsia should be aimed at reducing blood viscosity.
Competing interests: None declared
Competing interests: No competing interests
Other Predictive Markers of Pre-eclampsia
Pre-eclampsia in Cuba is one of the top five causes of obstetric morbidity, results which are similar to those reported by other countries of the northern hemisphere (2-8%). It is evident that the deviations of the normality of the arterial pressure stocking become useful when they associate to decisive risk factors for the illness such as nulliparity, age, ethnicity, first line family history of pre-eclampsia-eclampsia, Chronic Hypertension, Metabolic Syndrome and Prethrombotic States ,among others .
Our hospital gives medical assistance to a population of about 400 000 inhabitants, with an annual average of 4 000 births. In a series of 368 patients who required admission at the Intensive Care Unit (1987 - 2006), due to complications related with the evolution of pre- eclampsia, it represented 0.09% of the total of births and in the prenatal controls 95% of them had an arterial tension stocking above the values considered as a positive test. Other predictive methods for the diagnosis of the illness are also considered.
In 1974, Gant and Cols demonstrated that 91 % of women who were pregnant for the first time whose diastolic pressure was not increased to 20 mmHg when they changed position from the DLI to the supine decubits (Roll Over Test) they stayed with a normal arterial pressure until the end of their pregnancy, meanwhile 93% of patients that presented an increase in their diastolic pressure to 20 mmHg or more developed Pregnancy Induced Hypertension. This test is carried out between the 28-32 gestational weeks measuring the arterial pressure every 5 minutes, at the level of the right arm in DLI until it stabilizes. Then the pregnant woman changes her position to decubits supine and the blood pressure (B.P) is measured 5 minutes later.
In the case that the diastolic pressure doesn’t increase to 20 mmHg or more, the test is negative and it excludes the probability of the development of the illness with a high degree of accuracy.
In a study carried out in a population of pregnant women assisted in our hospital in the period 2006-2007 (314), it was found that the positivity marker for the Gant Test was 20.5%. Out of the total and of patient 18.5% developed pre-eclampsia, that represented 93.5% of the patients with the positive test, being demonstrated the high positive predictive value of this test.
References:
1. Colin A Walsh, Laxmi V Baxi. Mean arterial pressure and prediction of pre-eclampsia. BMJ 2008; 336: 1079-1080.
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3. Olsen S, Secher NJ, Tabor A, Weber T, Walker JJ, Gluud C. Randomised clinical trials of fish oil supplementation in high risk pregnancies. Br J Obstet Gynaecol 2000; 107:382–395. MA
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Competing interests: None declared
Competing interests: No competing interests