The current work compares hemodynamics and ventricular functions in patients with different placental transfusions techniques; I-UCM C-UCM with DCC in preterm infants.
Despite all previously mentioned benefits of placental transfusion, the main potential drawback is relative rapid transfusions provided by the 3 techniques and rapid changes in hemodynamics in the vulnerable premature infants. This may not allow enough time for smooth transition and adaptation of cardiovascular system, especially in cord milking groups.
Another point that could be faced with cut cord milking is that the blood would be transfused after taking 1st breath and the available length of the cord segment to be milked might not be sufficient. However, this technique might be good alternative if the two other techniques couldn’t be done or missed to be done.
No difference was found among studied groups in terms of demographics. In the case of the DCC group, the type of delivery or anesthesia might affect the contractions of the uterus, and thus the amount of blood transfused. None of the studied groups demonstrated significant differences for those variables.
As Katheria et al, found no differences in pulse oxygen saturation and heart rate between the UCM and DCC groups of infants delivered by Caesarean section, their blood pressure was higher in UCM group in the first 15 hours of life.(17)However, in the present study, no significant difference was observed among the three studied groups in terms of mean blood pressure, heart rate, or saturation in the first 24 hours.
No significant differences were found among the three groups regarding temperature on admission. This might be attributed to short duration of procedure in intact cord milking, transfusion of warm blood in the DCC and the use of servo-controlled heater during cut cord milking.
Whether different techniques of placental transfusion have similar effect on Hb level is point of debate in various studies. Kilicdag and Shrink showed no significant difference regarding HB level between C-UCM and I-UCM, and DCC and I-UCM, respectively. (18, 19) While Katheria et al showed significant difference in Hb levels between DCC and I-UCM in preterm infants born by cs, where infants in DCC group are expected to have lower Hb levels owing to lack of effective uterine contractions in their mothers.(17)
In the current work, the mean values of hemoglobin in the three groups were more than 15 g/dl. Although the results were not statistically significant, the I-UCM group had a tendency toward higher hemoglobin levels and fewer newborns with hemoglobin concentrations below 15 mg/dl, which also suggests that I-UCM may be a better choice in premature neonates.
An observation was made in the DCC group that 29 weeker male patient had the lowest initial hemoglobin level (10 mg/dl) and the highest WBCs (80 ×103 ul), the umbilical cord was noted as being pale and whitish in color and had a very little amount of blood to be transfused at birth. However, the case was not excluded because he had none of the exclusion criteria. Right IVH grade1 was noted on day1 with, SVC was 171.7 ml/kg/min, LVO was 397 ml/kg/min, RVO 409ml/kg/min ductal shunt was unrestricted on the first day of life, and the D3-SVC flow decreased to 90.3 ml/kg/min on the third day after receiving packed cell transfusion on day2.
The lowest SVC flow is usually recorded around 3–12 h after birth, with a gradual increase thereafter until 24–48 h after birth. After the transitional phase, the SVC flow remains relatively stable at 85–90 mL/kg/min in preterm infants. (20)
In the First 24 hours, placental transfusion might be one of principal factors affecting hemodynamics and myocardial function in the study population. In the 2nd scan after day3 might represents partial recovery from effect of placental transfusion and might be affected by other postnatal factors such asepsis related illness, mechanical ventilation, and the use of inotropes.(21)
SVC flow is significantly higher in the DCC group in the first 24 hours after birth than I-UCM and C-UCM groups. This difference disappeared after day3. The relative increase in SVC flow in the 1st 24hours might played a role in lack of occurrence of catastrophic IVH in the 3 studied group. Moreover, only 2 patients developed IVH grade 1 in the DCC group with significantly higher mean values of SVCF. SVCF is a measure of systemic blood flow as well as RVO and LVO. Therefore, patients in the DCC group tend to have higher RVO and LVO.
In the current study, we used TAPSE, and EF and FS to evaluate systolic function of right and left ventricles, respectively. Left vent diastolic function was evaluated using A/E ratio.
There is scarcity of data about normative and reference values of echocardiographic parameters in preterm infants. (22) Noori et al in their observational study on 29 preterm infants with (gestational age = 26.2+/- 1.5 weeks) reported that average FS was 34%±5% (range 23–48%) in the first 3 postnatal days in hemodynamically stable preterm infants. (23) Left ventricular dysfunction can be classified into the following: mild (FS 20–25%), moderate (FS 15–19%), and severe (FS ≤ 14%).(22) In the current work 8/19, 8/19, and 10/19 patients have FS less than 23% in C-UCM, I-UCM, and DCC, respectively. However,2 out of those26 patient only needed inotropic support and only three of them have LVO < 120ml/kg /min. This might indicate that normative values might be adjusted to a lower level in premature infants. It is also probably that rapid autotransfusion by the three placental transfusion techniques might have affected LV systolic function. Taking into consideration that FS and EF measured by Linear Left Ventricular Minor-axis Dimensions reflect movement of region of LV along the cursor line of M-mode, so it underestimates the entire LV contractile function.
LV E/A ratio is normal for the 3 study groups as lower accepted value is 0.7:1 in premature infants (24) with no significant difference among 3 studied groups. TAPSE is significantly lower in DCC group despite still being within physiological range of premature infants and this difference disappeared after day3. The lowest accepted value for TAPSE in premature neonates is 4mm. (25)This finding is similar to what happens in recipient fetus in TTT syndrome with more affection of right ventricle by volume overload. After fetoscopic laser coagulation of the connecting vessel, rapid normalization of cardiac function occurs. (26)
Early and rapid volume expansion might have detrimental effect on ventricular function in preterm infants. (27) The immature myocardium has limited ability to tolerate over transfusion or rapid transfusions with decreased contractile reserve as only 30% of the fetal myocardium contains contractile mass in contrast to 60% in the adult.(28) The right ventricle is more vulnerable to transfusion intolerance. RV has a higher resting tension than the adult RV, leading to lower ventricular compliance in utero and early neonatal life.(28) Coronary flow is related to pressure Difference between aortic root to the RA. When RA pressure escalates, thus, the flow in RCA might be insufficient leading to transient wall ischemia .(29) In the current work, DCC patients are affected more than the other 2 groups. This could have 2explanation: first, the amount of transfused blood might be higher in DCC patients. DCC for 30–45 s in preterm infants resulted in upto 28ml/kg increase in blood volume, while, I-UCM with 30cm cord segment and C-UCM for 4times may increase blood volume by 8ml/kg, 14ml/kg, respectively. (30) Second, patients of DCC group have lower birthweight and gestational age, Table1 and TAPSE values increase linearly with gestational age and birth weight. (31)Yao et al suggested that late cord clamping, by allowing a sizable placental transfusion, appeared to affect adversely the left ventricular performance of the neonate.(32)
Limitations
In our trial, we were limited by the lack of an ICC group. This might justify absence of significant differences in most of echocardiographic parameters between the three evaluated groups, because these approaches resulted in increased SBFs and altered hemodynamics. It was also important to note that the sample size of the three groups was relatively small in the present study.
The study was also limited by the inability to measure the SVC flow and cardiac output more than two times, since the SVC flow tends to vary widely during the first days of life. A further limitation of the study was the fact that no actions were taken when the SVC flow decreased, as the study was designed as a prospective cohort study. We did not evaluate diastolic function of RV that might be affected by placental transfusions more than diastolic function left ventricle.