Comparative study of erythrocyte deformability in maternal and cord blood

Three-dimensional refractive index tomograms and deformability of individual human red blood cells from cord blood of newborn infants and maternal blood

Red blood cells (RBCs) from the cord blood of newborn infants have distinctive functions in fetal and infant development. To systematically investigate the biophysical characteristics of individual cord RBCs in newborn infants, a comparative study was performed on RBCs from the cord blood of newborn infants and from adult mothers or nonpregnant women using optical holographic microtomography. Optical measurements of the distributions of the three-dimensional refractive indices and the dynamic membrane fluctuations of individual RBCs were used to investigate the morphological, biochemical, and mechanical properties of cord, maternal, and adult RBCs at the individual cell level. The volume and surface area of the cord RBCs were significantly larger than those of the RBCs from nonpregnant women, and the cord RBCs had more flattened shapes than that of the RBCs in adults. In addition, the hemoglobin (Hb) content in the cord RBCs from newborns was significantly higher. The Hb concentration in the cord RBCs was higher than that in the nonpregnant women or maternal RBCs, but they were within the physiological range of adults. Interestingly, the amplitudes of the dynamic membrane fluctuations in cord RBCs were comparable to those in nonpregnant women and maternal RBCs, suggesting that the deformability of cord RBCs is similar to that of healthy RBCs in adults.

Evaluation of Red Blood Cell Deformability and Uterine Blood Flow in Pregnant Women with Preeclampsia or IUGR and Reduced Uterine Blood Flow Following the Intravenous Application of Magnesium

OBJECTIVE

Red blood cells (RBC) deformability is one of the factors determining microcirculation. In preeclampsia (PE) and some cases of intrauterine growth restriction (IUGR), RBC deformability and, consequently, microcirculation appear to be impaired. Magnesium sulfate is administered to reduce the risk of seizures in PE. The aim of our study was to detect the effect of 24-hour intravenous (IV) magnesium on RBC deformability and on uterine artery blood flow in pregnant patients with preeclampsia or IUGR and pathologic uterine blood flow.

METHODS

Magnesium IV (1 g/h) was administered to 25 pregnant women with reduced uterine blood flow for a period of at least 24 hours. The RBC deformability was measured by uterine artery Doppler. Measurements were taken before the start of magnesium therapy and 24 h later. Magnesium plasma levels were measured at the same time.

RESULTS

High plasma levels of magnesium improve RBC deformability from E = 0.109 (SD +/- 0.023) to E = 0.115 (SD +/- 0.021) after 24 h IV magnesium (p = 0.043). There is no correlation of E to the plasma magnesium level either before or after 24 h magnesium treatment. Blood volume flow in the uterine arteries increased significantly from 5.09 mL/s (SD +/- 3.03) to 10.02 mL/s (SD +/- 5.86) after 24 h magnesium (p = 0.0002). The differences in the resistance index do not significantly differ from 0 (p = 0.46).

CONCLUSION

A high IV dosage of magnesium over a period of 24 hours dilates the uterine arteries of pregnant women with PE and/or IUGR, reduces uterine blood flow and improves the deformability of RBC. Both parameters enhance the oxygen supply to the fetus, a clinical parameter in these pregnancies. Thus magnesium might not only be effective as phrophylaxis against seizures but also in cases of IUGR with a reduced uterine blood flow. The clinically observed beneficial effect of magnesium in PE could be due to the improved blood supply for the fetus.

Effect of Magnesium on Red Blood Cell Deformability in Pregnancy

OBJECTIVE

Red blood cell (RBC) deformability is an important factor in determining movement of red blood cells through the microcirculation. In preeclampsia and some cases of intrauterine growth restriction (IUGR), RBC deformability and microcirculation are reduced. Magnesium is administered to reduce the risk of seizures. The aim of this study was first to detect the effect of intravenous magnesium application (2 g/h) on the deformability of RBCs in pregnancies with normal RBC deformability, receiving magnesium as tocolytic agent. The second aim was to examine the effect of calcium-antagonists (magnesium, nifedipin) on the deformability of RBC of preeclamptic patients in vitro.

METHODS

Part 1: magnesium (2 g/h), fenoterol (270 microg/h)+verapamil (0.2 mg/h) or placebo (NaCl 0.9%) was administered intravenously to pregnant women with premature contractions to test the tocolytic effect. RBC-deformability was measured by laser diffractoscopy in all three groups. Blood samples were taken before, after 1 h and after 24 h of administration. Magnesium-plasma-levels were measured. Part 2: Blood samples from patients with preeclampsia were incubated in vitro with magnesium (2 mmol), nifedipine (0.25 mg/ml), or placebo (NaCl 0.9%). RBC deformability was measured before and 15 min, 1 h, 2 h, 6 h, and 10 h after start of the incubation.

RESULTS

Part 1: The initial RBC-deformability was the same in all groups (E=0.232+/-0.017 in NaCl, 0.232+/-0.023 in fenoterol+verapamil, 0.232+/-0.019 in magnesium). After 1 h of administration, RBC-deformability was significantly greater with magnesium (0.254+/-0.020) and Fenoterol+Verapamil (0.238+/-0.02) compared to placebo (0.231+/-0.015). After 24 h the effect on RBC deformability in the fenoterol+verapamil-group was gone (0.234+/-0.021 compared to 0.234+/-0.016 in placebo), while in the IV-magnesium-group RBC-deformability remained increased (E=0.241+/-0.019). Statistical analysis of the influence of magnesium-plasma-levels showed the maximum effect at concentrations of 1.95-2.15 mmol/l. Part 2: RBC-deformability in preeclampsia was reduced as predicted by previous studies (0.120+0.0086 versus 0.232 in normal pregnancy). In vitro incubation with magnesium enhanced RBC-deformability in preeclampsia. Even after 15 min, a statistically significant effect was seen (0.127+/-0.0091 versus 0.121+/-0.0091 in placebo). Maximum effect was reached after 6 h of incubation (0.159+/-0.0093 versus 0.133+/-0.0091). Incubation with Nifedipine also enhanced RBC deformability [0.127+/-0.0091 after 15 min, 0.149+/-0.010 after 6 h (maximum effect)], but the effect was less pronounced than with magnesium.

CONCLUSION

Intravenous magnesium therapy over a 24-hour period increases RBC-deformability even in pregnancies with normal RBC-deformability. In vitro measurements show an increase of RBC-deformability in preeclampsia in response to magnesium, which could offer additional therapeutic benefit for the treatment of reduced blood flow seen in most cases of preeclampsia.

Maternal mean corpuscle volume and oxytocin augmentation during vaginal delivery

OBJECTIVE

The aim of this study was to assess whether low maternal MCV values are associated with adverse course of vaginal delivery.

STUDY DESIGN

A retrospective analysis of 92 consecutive vertex singleton vaginal deliveries in nulliparous women in a university tertiary health care facility. MCV was considered as major outcome variable.

RESULTS

54.1% of Parturients with higher MCV needed oxytocin augmentation during labor as compared to 79.5% of parturients with lower MCV (P<0.05). The need for oxytocin for augmentation of labor was decreased with larger MCV (OR 0.90 per fL, 95% CI 0.82-0.98, P<0.05). No correlation was found between MCV and other parameters of labor course.

CONCLUSION

Low maternal MCV values were associated with increased use of oxytocin augmentation during vaginal delivery.

Red blood cell survival and kinetics during pregnancy

Profound changes occur during pregnancy in the maternal hematopoietic system in order to meet the needs of the developing fetus and of the mother. By presenting the available data in one review, this review links all known hematopoietic events that occur during normal and certain abnormal pregnancies. Erythropoietin and erythrocyte production are increased during normal pregnancy while erythrocyte mass per unit of body weight remains constant throughout the entire pregnancy, and hemoglobin and hematocrit continuously decrease into the third trimester. Erythrocyte life span is decreased during normal pregnancy due to 'emergency hemopoiesis' in response to elevated erythropoietin levels. In preeclampsia, maternal erythrocytes are of similar to non-pregnant state age distribution, while fetal erythrocytes are of younger age distribution than in normal pregnancy. In gestational diabetes, maternal erythrocyte age distribution is similar to that of normal pregnancy. In multifetal pregnancy, maternal erythrocyte age distribution is younger than that of normal pregnancy.