Analysis of maternal circulation and renal function in physiologic pregnancies; parallel examinations of the changes in the cardiac output and the glomerular filtration rate

Maternal microvascular dysfunction during preeclamptic pregnancy

Preeclampsia is a hypertensive disorder of pregnancy effecting ∼5-8% of pregnancies in the United States, and ∼8 million pregnancies worldwide. Preeclampsia is clinically diagnosed after the 20th week of gestation and is characterized by new onset hypertension accompanied by proteinuria and/or thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, or cerebral or visual symptoms. This broad definition emphasizes the heterogeneity of the clinical presentation of preeclampsia, but also underscores the role of the microvascular beds, specifically the renal, cerebral, and hepatic circulations, in the pathophysiology of the disease. While the diagnostic criteria for preeclampsia relies on the development of de novo hypertension and accompanying clinical symptoms after 20-week gestation, it is likely that subclinical dysfunction of the maternal microvascular beds occurs in parallel and may even precede the development of overt cardiovascular symptoms in these women. However, little is known about the physiology of the non-reproductive maternal microvascular beds during preeclampsia, and the mechanism(s) mediating microvascular dysfunction during preeclamptic pregnancy are largely unexplored in humans despite their integral role in the pathophysiology of the disease. Therefore, the purpose of this review is to provide a summary of the existing literature on maternal microvascular dysfunction during preeclamptic pregnancy by reviewing the functional evidence in humans, highlighting potential mechanisms, and providing recommendations for future work in this area.

Maternal kidney function during pregnancy: systematic review and meta-analysis

OBJECTIVES

To review systematically current literature on kidney function changes during pregnancy, in order to estimate the extent of adaptation over the course of both healthy physiological and complicated singleton pregnancies, and to determine healthy pregnancy reference values.

METHODS

PubMed (NCBI) and EMBASE (Ovid) electronic databases were searched, from inception to July 2017, for studies on kidney function during uncomplicated and complicated pregnancies. Included studies were required to report a non-pregnant reference value of kidney function (either in a non-pregnant control group or as a prepregnancy or postpartum measurement) and a pregnancy measurement at a predetermined and reported gestational age. Kidney function measures assessed were glomerular filtration rate (GFR) measured by inulin clearance, GFR measured by creatinine clearance and serum creatinine level. Pooled mean differences between pregnancy measurements and reference values were calculated for predefined intervals of gestational age in uncomplicated and complicated pregnancies using a random-effects model described by DerSimonian and Laird.

RESULTS

Twenty-nine studies met the inclusion criteria and were included in the analysis. As early as the first trimester, GFR was increased by up to 40-50% in physiological pregnancy when compared with non-pregnant values. Inulin clearance in uncomplicated pregnancy was highest at 36-41 weeks, with a 55.6% (53.7; 95% CI, 44.7-62.6 mL/min) increase when compared with non-pregnant values, and creatinine clearance was highest at 15-21 weeks' gestation, with a 37.6% (36.6; 95% CI, 26.2-46.9 mL/min) increase. Decrease in serum creatinine level in uncomplicated pregnancy was most prominent at 15-21 weeks, with a 23.2% (-0.19; 95% CI, -0.23 to -0.15 mg/dL) decrease when compared with non-pregnant values. Eight studies reported on pregnancies complicated by a hypertensive disorder. Meta-regression analysis showed a significant difference in all kidney function parameters when comparing uncomplicated and hypertensive complicated pregnancies.

CONCLUSIONS

In healthy pregnancy, GFR is increased as early as the first trimester, as compared with non-pregnant values, and the kidneys continue to function at a higher rate throughout gestation. In contrast, kidney function is decreased in hypertensive pregnancy. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Augmented renal clearance

Adding to the complexity of caring for critically ill patients is the fact that many of them have a creatinine clearance that exceeds 130 mL/min/1.73 m². This phenomenon, termed augmented renal clearance (ARC), has only recently been widely recognized and its pathogenesis remains incompletely understood. However, ARC has been shown to result in increased dose requirements for drugs that are primarily eliminated by renal excretion, including many antimicrobial agents and enoxaparin. Recognition of ARC is hampered by the fact that the standard creatinine-based equations used to estimate renal function are not accurate in this clinical setting and the diagnosis is best established using both serum and urine creatinine measurements to calculate clearance. So a high index of clinical suspicion and awareness is usually required before this step is taken to confirm the diagnosis of ARC.

Cardiac Arrest in Pregnancy

This is the first scientific statement from the American Heart Association on maternal resuscitation. This document will provide readers with up-to-date and comprehensive information, guidelines, and recommendations for all aspects of maternal resuscitation. Maternal resuscitation is an acute event that involves many subspecialties and allied health providers; this document will be relevant to all healthcare providers who are involved in resuscitation and specifically maternal resuscitation.

Changes in choroidal thickness during pregnancy detected by enhanced depth imaging optical coherence tomography

AIM

To compare the choroidal thickness measurements of healthy pregnant women obtained in the first trimester with measurements obtained in the third trimester using enhanced depth imaging optical coherence tomography (OCT).

METHODS

54 eyes of 27 healthy pregnant women and 50 eyes of 25 age matched healthy women were enrolled in this observational, cross-sectional study. The pregnant women underwent two OCT scans, one in the first trimester at gestational weeks 6-8, and the other during the third trimester at gestational weeks 32-37; the control group had OCT scanning during the follicular phase of the menstrual cycle, using the enhanced depth imaging mode. Choroidal thicknesses were measured at the fovea, at three locations nasal, and at three locations temporal to the fovea at 500 μm intervals.

RESULTS

The choroidal thickness measurements obtained in the third trimester were significantly decreased in all measured points in both eyes compared to the measurements obtained in the first trimester (p<0.05). At the fovea, the mean (±SD) choroidal thickness measured in the first trimester was 349.22±82.11 μm in the right eyes and 341.30±85.22 μm in the left eyes, which decreased to 333.56±76.61 μm in the right eyes (p=0.014) and 326.93±75.84 μm in the left eyes (p=0.024) in the third trimester. Although not statistically significant, choroidal thicknesses of the control group were less than the choroidal thicknesses of the pregnant women (p>0.05).

CONCLUSIONS

Choroidal thickness was found to be significantly decreased in healthy pregnant women during the third trimester compared to the first trimester. This finding can provide valuable information when interpreting pregnancy related ocular disorders.

Postpartum anemia I: definition, prevalence, causes, and consequences

This review provides a status on the definition, prevalence, causes, and consequences of anemia in women who have given childbirth, i.e., postpartum anemia. The diagnosis of iron deficiency anemia relies on a full blood count including hemoglobin, serum ferritin, and serum soluble transferrin receptor, which appear to be reliable indicators of anemia and iron status 1 week postpartum while serum transferrin saturation is an unreliable indicator several weeks after delivery. It is recommended that postpartum anemia should be defined by hemoglobin <110 g/L at 1 week postpartum and <120 g/L at 8 weeks postpartum. The major causes of postpartum anemia are prepartum anemia combined with acute bleeding anemia due blood losses at delivery. Normal peripartum blood losses are approximately 300 ml, but hemorrhage >500 ml occur in 5-6% of the women. In healthy women after normal delivery, the prevalence of anemia (hemoglobin <110 g/L) 1 week postpartum is 14% in iron-supplemented women and 24% in non-supplemented women. In consecutive series of European women, the prevalence of anemia 48 h after delivery is approximately 50%. In developing countries, the prevalence of postpartum anemia is in the range of 50-80%. Postpartum anemia is associated with an impaired quality of life, reduced cognitive abilities, emotional instability, and depression and constitutes a significant health problem in women of reproductive age.

Echocardiographic Assessment of Cardiovascular Hemodynamics in Normal Pregnancy

OBJECTIVE

The factors affecting cardiac output in normal pregnancy remain controversial. This study prospectively evaluates maternal central hemodynamics and cardiac structure and function by echocardiography, together with maternal stature correction and correlation of these variables in healthy pregnant women in the latter half of pregnancy.

METHODS

One hundred sixty echocardiographic studies were performed in 35 healthy pregnant women for longitudinal evaluation from early second trimester until term and 6-12 weeks postpartum.

RESULTS

Cardiac output increased significantly at the early to mid third trimester and was maintained until term. It increased predominantly in the latter half of pregnancy, and peak cardiac output of 46-51% occurred from a 15% increase in heart rate and 24% increase in stroke volume. Maternal cardiac output measured in the early third trimester showed a good correlation with maternal body surface area (r = 0.72; P <.001) and fetal birth weight (r = 0.52; P =.008). Left ventricular systolic function was preserved until term.

CONCLUSION

Maternal cardiac output peaks in the early to mid third trimester and is maintained until term. Significant correlations were observed among maternal cardiac output, maternal body surface area, and fetal birth weight.