Residual Blood Volume Research Articles

Effects of plateletpheresis on hematological parameters

Apheresis for platelet concentrates has been used more frequently in recent years due to the rising demand for platelet transfusions for patients with various medical and surgical disorders. Studies on the effect of repeated or frequent plateletpheresis on the donor's hematological parameters are still limited. This article will review the effects of plateletpheresis on the donor's hematological parameters to define the proper deferral for repeat donation because this treatment is relatively new and requires early repeat donations. We systematically search the studies and review current evidence about the effects of plateletpheresis on blood parameters in healthy donors. Literature tracking was performed on PubMed, CENTRAL, EbscoHost, and ProQuest databases. There are different effects, and some studies reveal that plateletpheresis can decrease hematological parameters (HB, HCT, PLT, PDW). Some can cause an increase in hematological parameters (HB, HCT). These different effects can be caused by variable cell separator technologies, residual blood volume lost during apheresis, and mechanical hemolysis of blood in tubes by machine pumps.

Direct Derivatization in Dried Blood Spots for Oxidized and Reduced Glutathione Quantification in Newborns.

The glutathione (GSH)-to-glutathione disulfide (GSSG) ratio is an essential node contributing to intracellular redox status. GSH/GSSG determination in whole blood can be accomplished by liquid chromatography–mass spectrometry (LC-MS) after the derivatization of GSH with N-ethylmaleimide (NEM). While this is feasible in a laboratory environment, its application in the clinical scenario is cumbersome and therefore ranges reported in similar populations differ noticeably. In this work, an LC-MS procedure for the determination of GSH and GSSG in dried blood spot (DBS) samples based on direct in situ GSH derivatization with NEM of only 10 µL of blood was developed. This novel method was applied to 73 cord blood samples and 88 residual blood volumes from routine newborn screening performed at discharge from healthy term infants. Two clinical scenarios simulating conditions of sampling and storage relevant for routine clinical analysis and clinical trials were assessed. Levels of GSH-NEM and GSSG measured in DBS samples were comparable to those obtained by liquid blood samples. GSH-NEM and GSSG median values for cord blood samples were significantly lower than those for samples at discharge. However, the GSH-NEM-to-GSSG ratios were not statistically different between both groups. With DBS testing, the immediate manipulation of samples by clinical staff is reduced. We therefore expect that this method will pave the way in providing an accurate and more robust determination of the GSH/GSSG values and trends reported in clinical trials.

Effects of Umbilical Cord Management Strategies on Stem Cell Transfusion, Delivery Room Adaptation, and Cerebral Oxygenation in Term and Late Preterm Infants.

Background:The umbilical cord blood contains a high concentration of stem cells. There is not any published study evaluating the amount of stem cells that have the potential to be transferred to the infant through placental transfusion methods as delayed cord clamping (DCC) and umbilical cord milking (UCM). The aim of this study is to measure the concentrations of endothelial progenitor cell (EPC) and CD34+ hematopoietic stem cell (HSC) in the placental residual blood volume (PRBV), and evaluate the delivery room adaptation and cerebral oxygenation of these infants.MethodsInfants with ≥36 gestational weeks were randomized to receive DCC (120 s), UCM, or immediate cord clamping (ICC). EPC and CD34+ HSC were measured by flow cytometry from the cord blood. PRBV was collected in the setup. The cord blood gas analysis and complete blood count were performed. The heart rate (HR), oxygen saturation (SpO2), and cerebral regional oxygen saturation (crSO2) were recorded.ResultsA total of 103 infants were evaluated. The amount of PRBV (in ml and ml/kg) was higher in the ICC group (p < 0.001). The number of EPCs in the PRBV content (both ml and ml/kg) were the highest in the ICC group (p = 0.002 and p = 0.001, respectively). The number of CD34+ HSCs in PRBV content (ml and ml/kg) was similar in all groups, but nonsignificantly higher in the ICC group. The APGAR scores at the first and fifth min were lower in the ICC group (p < 0.05). The mean crSO2 values were higher at the 3rd and 10th min in the DCC group (p = 0.042 and p = 0.045, respectively). cFOE values were higher at the 3rd and 10th min in the ICC group (p = 0.011 and p < 0.001, respectively).ConclusionThis study showed that placental transfusion methods, such as DCC and UCM, provide both higher blood volume, more stem cells transfer to the infant, and better cerebral oxygenation in the first minutes of life, whereas many lineages of stem cells is lost to the placenta by ICC with higher residual blood volume. These cord management methods rather than ICC do not require any cost or technology, and may be a preemptive therapeutic source for diseases of the neonatal period.

The Association Between Placental Residual Blood Volume and Two Placental Transfusion Methods After Delivery at Term.

Background: Despite reports of the beneficial effects, such as increasing hemoglobin level and iron store in the neonatal period, of delayed cord clamping, or umbilical cord milking after delivery in healthy term-born infants, the duration of delayed clamping or rounds of milking in most previous reports were determined arbitrarily and varied widely across different studies.Methods: We prospectively recruited 80 women with normal singleton pregnancies at 38–40 weeks' gestation. Participants were classified according to the mode of delivery and randomly assigned to either collecting blood from the placenta by umbilical cord drainage (CD) or cord milking (CM), with the placenta left in the uterus. The volume of blood collected, the duration of CD, and the number of rounds of CM were recorded.Results: Collected placental residual blood volume positively correlated with birth weight, placental weight, and length of the cord. When 80% of the total placental residual blood volume collected was set as the threshold, more than 80% of women who delivered vaginally reached this level within 60 s of CD or seven repetitions of CM. This amount of blood could be obtained within 120 s of CD or after seven repetitions of CM in more than 80% of women who underwent cesarean delivery.Conclusion: In most women, regardless of birth weight and placental weight, more than 80% of placental residual blood volume could be collected by CD within 60 s after vaginal delivery, 120 s after cesarean delivery, and seven repetitions of CM in both vaginal and cesarean deliveries.

Transcortical approach surgery versus external ventricular drainage in treating intraventricular hemorrhage.

Intraventricular hemorrhage is a serious intracerebral hemorrhagic disease with high mortality and poor prognosis. This retrospective study designed to investigate the therapeutic effect of transcortical approach surgery versus extraventricular drainage (EVD) on patients with intraventricular hemorrhage.Patients with intraventricular hemorrhage in Zhongshan City People's Hospital from January 01, 2014 to June 01, 2019 were retrospectively examined. They were divided into transcortical approach surgery groups and EVD groups to analyze the clinical characteristics and prognosis.A total of 96 patients were enrolled in the study (24 in the transcortical approach surgery group and 72 in the EVD group). The efficiency of postoperative operation was 15/19 in the transcortical approach surgery group and 24/48 in the EVD group (P = .012). The Glasgow Outcome Scale was 3.63 ± 1.27 in the transcortical approach surgery group and 2.80 ± 1.87 in the EVD group (P = .049). The postoperative residual blood volume was 9.62 ± 3.64 mL in the transcortical approach surgery group and 33.60 ± 3.53 mL in the EVD group (P < .001). The incidence of hydrocephalus after the operation was 1/23 in the transcortical approach surgery group and 19/53 in the EVD group. The 30-day postoperative mortality was 16/56 in the EVD group and 1/23 in the transcortical approach surgery group. The transcortical approach surgery group was significantly better compared with the EVD group.This study showed that the transcortical approach for ventricular hemorrhage compared with EVD improved the hematoma clearance rate, shortened catheterization time, reduced the incidence of postoperative hydrocephalus, decreased patient mortality, led to a better prognosis, and reduced complications of hydrocephalus.

Nutritional status and volume control in adolescents on chronic hemodialysis.

Pediatric patients on maintenance hemodialysis (HD) are at risk of both malnutrition and fluid overload. This pilot study aimed to assess correlates of normalized protein catabolic rate (nPCR) in adolescents on chronic HD, in particular fluid status markers. All patients aged 10-18 years on chronic HD in our center between 2017 and 2019 were enrolled. For each patient, mean nPCR was calculated and correlations with the following parameters investigated: dry body weight change in subsequent 3 months in kg (∆BW) and percentage of BW (∆BW%), change in body mass index (∆BMI), preHD systolic and diastolic blood pressure (SBP, DBP), residual urine output, biochemistry, and blood volume monitoring-derived first hour refill index (RI), calculated as ratio between ultrafiltration rate and reduction in relative blood volume in first hour of dialysis. Seventy-nine nPCR determinations were collected in 23 patients, median age 14.8 years. nPCR significantly correlated with ∆BW, ∆BW%, ∆BMI, spKT/V, and preHD serum creatinine, and negatively correlated with age, DBP SDS (r=-0.466, p=0.025) and RI (r=-0.435, p=0.043). RI was significantly higher in patients with nPCR <1 than those with nPCR above this threshold: 3.2 (1.9-4.7) vs. 1.4 (0.7-1.8) ml/kg/h/% (p=0.021). At multivariable analysis, nPCR remained positively correlated with creatinine and spKt/V, and inversely correlated with RI. nPCR is a significant predictor of weight change in adolescents on maintenance HD, and seems associated with creatinine and dialysis adequacy. Inverse correlation with RI suggests possible associations between malnutrition and fluid overload, but larger prospective studies are needed to confirm this. A higher resolution version of the Graphical abstract is available as Supplementary information.

Physiological parameter values for physiologically based pharmacokinetic models in food-producing animals. Part III: Sheep and goat.

This report is the third in a series of studies that aimed to compile physiological parameters related to develop physiologically based pharmacokinetic (PBPK) models for drugs and environmental chemicals in food‐producing animals including swine and cattle (Part I), chickens and turkeys (Part II), and finally sheep and goats (the focus of this manuscript). Literature searches were conducted in multiple databases (PubMed, Google Scholar, ScienceDirect, and ProQuest), with data on relevant parameters including body weight, relative organ weight (% of body weight), cardiac output, relative organ blood flow (% of cardiac output), residual blood volume (% of organ weight), and hematocrit reviewed and statistically summarized. The mean and standard deviation of each parameter are presented in tables. Equations describing the growth curves of sheep and goats are presented in figures. When data are sufficient, parameter values are reported for different ages or production classes of sheep, including fetal sheep, lambs, and market‐age sheep (mature sheep). These data provide a reference database for developing standardized PBPK models to predict drug withdrawal intervals in sheep and goats, and also provide a basis for extrapolating PBPK models from major species such as cattle to minor species such as sheep and goats.

Less Residual placental blood volume left when cord pulsation ceases than when early cord clamping at 60 seconds

Objectives: Our goal was to test the volume of residual placental blood volume (RPBV) left with delayed cord clamping occurring when pulsation of the umbilical artery ceases as compared to early cord clamping at 60 seconds along with an assessment of its effects on maternal and neonatal outcomes. Materials and Methods: From March to June 2015 in Haikou maternal and child health hospital, 403 single-term patients with normal vaginal births and healthy babies were enrolled with randomization into two groups. The experimental group (n = 201) received delayed cord clamping after pulsation of the umbilical artery ceased with the control group (n = 202) having the umbilical cord cut at exactly 60 seconds. RPBV was collected when the cord was cut in both groups. Maternal and neonatal conditions were recorded. Results: In the control group, RPBV per birth weight (RPBV (mL/kg) range) [21.0 ± 14.9 (2.9-73.2)] was higher than that in experimental group [4.3 ± 3.5 (0.8 - 19.1)] (p &lt; 0.01); peak total serum bilirubin (TSB) level (mg/dL) [(13.6 ± 3.5) (5.0 - 20.7) mg/d1] was higher in the control than that in experimental group [11.9 ± 2.9 (4.5 - 24.5)] (p &lt; 0.01); and postpartum blood loss in control group [(187.8 ± 104.6) (80-650.00) mL] was higher than that in experimental group [(160.2 ± 72.9) (70 - 450) mL] (p = 0.02). Maternal age, gestational age and Apgar score at one and five minutes were not of statistically different between groups. No neonatal deaths were recorded in either group at one month’s follow up. Conclusions: Delayed cord clamping until the umbilical artery pulsation ceased is a safe intervention and reduces the residual placental blood volume without any adverse maternal or neonatal effects. The data suggests that more placental transfusion occurs in the newborn with delayed cord clamping.

Comparison of cut and intact cord milking regarding cerebral oxygenation, hemodynamic and hematological adaptation of term infants

Objective Although both delayed umbilical cord clamping and intact umbilical cord milking (I-UCM) provide the effective placental transfusion at birth, these procedures may not be used in neonates needing resuscitation. The aim of this study is to investigate the effect of cut umbilical cord milking (C-UCM), which permits resuscitation during an immediate transition period (ITP). Methods Sixty-two healthy term infants were randomly divided into C-UCM and I-UCM groups at birth. Approximately 30-cm length of cord was milked towards the baby 2–4 times within 20 seconds after birth in both C-UCM and I-UCM groups while the umbilical cord was cut in the former, and intact in the latter. Heart rate, arterial oxygen saturation (SpO2), cerebral regional oxygen saturation (crSO2) (2nd–15th min), blood pressure (BP) (within 15–30 min), residual placental blood volume (RPBV), and hemoglobin levels (at the sixth hour) were monitored during ITP. Results There were no significant differences in terms of mean gestational age (w) [(39.0 ± 1.2) versus (38.8 ± 1.1)], birth weight (g) [(3351.45 ± 254.30) versus (3256.94 ± 285.52)], Apgar scores at the 5th min (10 ± 0 versus 10 ± 0), first breathing time (sec) (5.4 ± 3.8 versus 5.7 ± 4.1), SpO2, crSO2, BP (mmHg) [(52.9 ± 6.9) versus (51.8 ± 5.7)], hemoglobin levels (g/dl) [(17.7 ± 1.8) versus (18.4 ± 1.4)], and RPBV (ml/kg) [(23.9 ± 4.7) versus (22.9 ± 5.4)] between C-UCM and I-UCM groups (p > .05). Conclusion This study showed that C-UCM is as effective as I-UCM on cerebral oxygenation, hemodynamic and hematological adaptation of term infants in ITP. We suggest that C-UCM can provide additional placental transfusion in term neonates exposed to early cord clamping.

The residual blood from segmental umbilical cord milking in preterm delivery

Umbilical cord milking is an alternative procedure providing blood to infants but there is no study in the proper length of umbilical cord and various gestational age. The aim of this study was to measure the blood volume in the umbilical cord of preterm infants at a certain length and to identify the correlation among blood volume, length, and circumference of umbilical cord, gestational age (GA), birth weight and placenta. Seventy-five pregnant women aged 18 years old and above with 24–36+6 weeks of gestation were included in this cross-sectional study. After delivery, a 15 to 45 cm of umbilical cord was cut and parameters of umbilical cord were recorded. The mean GA at birth was 241.84 ± 20.06 days. The mean length, diameter, and circumference were 23.31 ± 7.66, 1.10 ± 0.18, and 3.56 ± 0.75 cm, respectively. The mean residual blood volume was 11.58 ± 4.99 mL or 0.50 ± 0.18 mL/cm. Total residual blood volume had a significant positive strong correlation with umbilical cord length (r = 0.720, p < .001). To reduce complications from blood overload, the appropriate blood volume for preterm infant should be calculated from birth weight and umbilical cord length.Impact statementWhat is already known on this subject? The World Health Organisation recommends delayed cord clamping for newborn infants which neonatal resuscitation was not indicated but the majority of preterm infants needed resuscitation. Umbilical cord milking is an alternative procedure providing blood to infants. A small volume transfusion (10–20 m/kg) is commonly used for replacement in preterm neonates. Although there is a concern about the blood volume transferred into infants, blood volume and proper length of umbilical cord have not been thoroughly investigated.What do the results of this study add? In this study, the mean residual blood volume was 0.5 mL/cm and total residual blood volume had a significant positive strong correlation with umbilical cord length. In subgroup of very low birth weight group, the mean residual blood volume was 0.41 mL/cm; however, there was no statistically significant difference from other birth weight groups.What are the implications of these findings for clinical practice and/or further research? The appropriate length of umbilical cord for milking can be calculated from the estimated foetal weight and the mean residual blood volume per length (0.5 mL/cm); nevertheless, the calculation should be used with caution. The further study should investigate in extremely preterm or very low birth weight infants.

Abstract WMP98: Genetic Deletion of Haptoglobin Ameliorates Intracerebral Hemorrhage-induced Brain Damage

Background: The presence of extracorpuscular hemoglobin (Hb) exacerbates brain damage following intracerebral hemorrhage (ICH). Systemically, haptoglobin (Hp) is an acute phase glycoprotein that reduces brain injury by binding to extracellular Hb, which stabilizes the protein and prevents further toxic reactions. However, the properties of Hp within the brain during ICH are not well understood. This study aims to investigate the acute and chronic effects of haptoglobin deletion following ICH and the possibility that age influences the recovery outcomes. Methods: The ICH was induced in young and older aged (WT) controls and Hp -/- C57BL/6 mice using the autologous whole blood and collagenase injection models. Behavioral assessments of neurological deficit scoring, open field locomotor activity, and rotarod were conducted to investigate functional outcomes at 1d, 2d, 3d, 4d, 7d, and 10d. Various anatomical outcomes were measured through the staining for specific biomarkers following animal sacrifice at 3d and 10d. Results: At 3d, Hp -/- mice display 36.7±6.9% smaller lesions, 35.8 ± 9.5% less residual blood volume and 36.9±6.5% less tissue injury. At 10d, young Hp -/- mice show significant reduction in lesion volume. Behavioral assessments exhibit a reduction in neurological deficits in Hp mice. Similarly, young and old Hp -/- mice show significant differences in neurological deficit scores and open field locomotor activity at 3d and 10d. Additionally, Hp -/- mice display significantly less heme oxygenase 1 expression, less iron, and, less blood-brain barrier breakdown at 3d conversely, no significant differences are observed at 10d. Furthermore, Hp -/- mice show a reduction in hematomal vascular endothelial growth factor expression and ipsilateral motor cortex expression at 3d. Additionally, ipsilateral thalamic astrogliosis was less in young Hp -/- mice but no significance observed at 10d. Conclusion: The results of this study display the acute and chronic ameliorating effects of haptoglobin deletion in mice following ICH. Initially, Hp -/- mice have significant reductions in brain injury and later, perform similarly and occasionally better than WT controls.

Residual Placental Blood Volume Estimation to Measure the Increase in Neonatal Blood Transfer by Delayed Cord Clamping: A Quasi-Experimental Study

Residual Placental Blood Volume Estimation to Measure the Increase in Neonatal Blood Transfer by Delayed Cord Clamping: A Quasi-Experimental Study

Comparing of Residual Placental Blood Volume When Cord Pulsation Ceased with Early Cord Clamping at 60 Seconds

Comparing of Residual Placental Blood Volume When Cord Pulsation Ceased with Early Cord Clamping at 60 Seconds

Fixed volume particle trace emission for the analysis of left atrial blood flow using 4D Flow MRI

4D Flow MRI has been used to quantify normal and deranged left ventricular blood flow characteristics on the basis of functionally distinct flow components. However, the application of this technique to the atria is challenging due to the presence of continuous inflow. This continuous inflow necessitates plane-based emission of particle traces from the inlet veins, leading to particles that represents different amounts of blood, and related quantification errors. The purpose of this study was to develop a novel fixed-volume approach for particle tracing and employ this method to develop quantitative analysis of 4D blood flow characteristics in the left atrium. 4D Flow MRI data were acquired during free-breathing using a navigator-gated gradient-echo sequence in three volunteers at 1.5T. Fixed-volume particle traces emitted from the pulmonary veins were used to visualize left atrial blood flow and to quantitatively separate the flow into two functionally distinct flow components: Direct flow=particle traces that enter and leave the atrium in one heartbeat, Retained flow=particle traces that enter the atrium and remains there for one cardiac cycle. Flow visualization based on fixed-volume traces revealed that, beginning in early ventricular systole, flow enters the atrium and engages with residual blood volume to form a vortex. In early diastole during early ventricular filling, the organized vortical flow is extinguished, followed by formation of a second transient atrial vortex. Finally, in late diastole during atrial contraction, a second acceleration of blood into the ventricle is seen. The direct and retained left atrial flow components were between 44 and 57% and 43–56% of the stroke volume, respectively. In conclusion, fixed-volume particle tracing permits separation of left atrial blood flow into different components based on the transit of blood through the atrium.

Mathematical bias in assessment of placental residual blood volume.

Mathematical bias in assessment of placental residual blood volume.

The Effects of Placental Transfusion on Placental Residual Blood Volume and 24 to 48‐hour Hemoglobin and Serum Bilirubin in Term Newborns: A Randomized Controlled Trial

PurposeTo determine if newborns who receive a full placental transfusion at birth differ in placental residual blood volume (PRBV) and 24 to 48‐hour hemoglobin (Hb) and total serum bilirubin (TSB) levels compared to newborns who receive no placental transfusion.Research QuestionWill newborns who receive a full placental transfusion have less PRBV, a higher 24 to 48‐hour Hb, and no difference in peak TSB compared to newborns who receive no placental transfusion?SignificanceThe usual maternity care practice in the United States is to immediately clamp the umbilical cord (immediate cord clamping [ICC]) at the time of birth. When ICC occurs, 20% to 40% of the fetal‐placental blood volume (containing iron‐rich red blood cells) is left behind in the placenta, potentially leading to lower iron stores in infancy.MethodsA prospective randomized controlled trial was conducted. Seventy‐three healthy term pregnant women with singleton fetuses were enrolled. At birth, they were randomized to either ICC (&lt;20 seconds; n = 36) or delayed cord clamping (DCC) (≥5 minutes; n = 37) and then placed skin‐to‐skin. The primary endpoints were PRBV in mL/kg, Hb (g/dL), and peak TSB at 24 to 48 hours of age. Primary analyses were conducted by intention‐to‐treat and secondary analyses by actual treatment.ResultsMaternal and newborn demographics were not significantly different between groups. Mean (standard deviation [SD]) cord clamping time was 303 (121) seconds (DCC) versus 10 (6) (ICC) seconds (P = .001). Eleven newborns received cord milking as a proxy for DCC at the time of cesarean birth or when resuscitation measures were indicated. There were 9 protocol violations. Newborns randomized to DCC left behind less PRBV (20.0 vs 30.8 mL/kg, P &lt; .001). At 24 to 48 hours of age, newborns exposed to DCC had significantly higher Hb levels (19.5 vs 17.7 g/dL, P = .002) without a difference in peak TSB levels (DCC = 8.5 vs ICC = 9.0 mg/dL, P = .45) compared to infants with ICC. Two newborns in each group had phototherapy.DiscussionNewborns with ICC left behind more PRBV and had lower Hb levels at 24 to 48 hours. There was no difference between the groups on peak TSB levels or other indicators of hyperbilirubinemia. The results support the early hematological advantage of DCC while demonstrating no association with an increase in hyperbilirubinemia.

Effects of delayed cord clamping on residual placental blood volume, hemoglobin and bilirubin levels in term infants: a randomized controlled trial.

ObjectiveTo measure the effects of a five-minute delay (DCC) versus immediate cord clamping (ICC) on residual placental blood volume (RPBV) at birth, and hemoglobin and serum bilirubin at 24 to 48 hours of age.Study DesignIn this prospective randomized controlled trial, seventy-three women with term (37 to 41 weeks) singleton fetuses were randomized to DCC (≥5 minutes; n=37) or ICC (<20 seconds; n=36).ResultsMaternal and infant demographics were not different between groups. Mean cord clamping time was 303 ± 121 (DCC) versus 23 ± 59 (ICC) seconds (p<0.001) with 10 protocol violations. Cord milking was the proxy for DCC (n = 11) when the provider could not wait. Infants randomized to DCC compared to ICC had significantly less RPBV (20.0 vs 30.8 mL/kg, p<0.001), higher hemoglobin levels (19.4 vs 17.8 g/dL, p=0.002) at 24 to 48 hours, with no difference in bilirubin levels.ConclusionsTerm infants had early hematological advantage of DCC without increases in hyperbilirubinemia or symptomatic polycythemia.

Calculation of the Residual Blood Volume after Acute, Non-Ongoing Hemorrhage Using Serial Hematocrit Measurements and the Volume of Isotonic Fluid Infused: Theoretical Hypothesis Generating Study.

Fluid resuscitation, hemostasis, and transfusion is essential in care of hemorrhagic shock. Although estimation of the residual blood volume is crucial, the standard measuring methods are impractical or unsafe. Vital signs, central venous or pulmonary artery pressures are inaccurate. We hypothesized that the residual blood volume for acute, non-ongoing hemorrhage was calculable using serial hematocrit measurements and the volume of isotonic solution infused. Blood volume is the sum of volumes of red blood cells and plasma. For acute, non-ongoing hemorrhage, red blood cell volume would not change. A certain portion of the isotonic fluid would increase plasma volume. Mathematically, we suggest that the residual blood volume after acute, non-ongoing hemorrhage might be calculated as 0·25N/[(Hct1/Hct2)–1], where Hct1 and Hct2 are the initial and subsequent hematocrits, respectively, and N is the volume of isotonic solution infused. In vivo validation and modification is needed before clinical application of this model.

Residual blood volume in the umbilical cord of extremely premature infants.

The aim of this study was to investigate residual blood volume in the umbilical cord of extremely premature infants. Twenty extremely premature infants were held at or below the placenta while the umbilical cord was clamped and cut at approximately 2-3 cm from the umbilicus within 30 s after birth. The umbilical cord was then clamped near the placenta to obtain a length of approximately 30 cm and cut. The residual blood volume in the segment of cord was drained and measured in milliliters. Mean birthweight was 846 ± 172 g (range, 587-1180 g). The average length of the clamped segment of umbilical cord was 29.8 ± 1.5 cm (range, 27-32 cm). Total residual blood volume and residual blood volume per cm were 15.5 ± 6.7 mL (range, 6-25 mL) and 0.5 ± 0.2 mL/cm (range, 0.2-0.8 mL/cm), respectively. The residual cord blood volume per kilogram of infant weight per 30 cm was 17.7 ± 5.5 mL/kg/30 cm (range, 8.9-29.0 mL/kg/30 cm). Infants could receive approximately 18 mL/kg of whole blood by one-time milking of 30 cm umbilical cord. With an average hematocrit of 40%, this volume is equivalent to approximately 13 mL of packed red blood cells (hematocrit 55%).

Impact of cesarean section on placental transfusion and iron-related hematological indices in term neonates: A systematic review and meta-analysis

Evidence suggests that cesarean section is likely associated with a reduced placental transfusion and poor hematological status in neonates. However, clinical studies have reported somewhat inconsistent results. We conducted a systematic review and meta-analysis to examine whether cesarean section affects placental transfusion and iron-related hematological indices. Pubmed, Web of Science, ScienceDirect, and Ovid Databases were searched for relevant studies published before April 9, 2013. Mean differences between cesarean section and vaginal delivery in outcomes of interests (placental residual blood volume; hematocrit level, hemoglobin concentration, and erythrocyte count in cord/peripheral blood) were extracted and pooled using a random effects model. We identified 15 studies (n = 8477) eligible for the meta-analysis. Compared with neonates born vaginally, those born by cesarean section had a higher placental residual blood volume [weighted mean difference (WMD), 8.87 ml; 95% confidence interval (CI), 2.32 ml–15.43 ml]; a lower level of hematocrit (WMD, −2.91%; 95% CI, −4.16% to −1.65%), hemoglobin (WMD, −0.51 g/dL; 95% CI, −0.74 g/dL to −0.27 g/dL) and erythrocyte (WMD, −0.16 × 1012/L; 95% CI, −0.30 × 1012/L to −0.01 × 1012/L). Subgroup analysis showed that the WMD for hematocrit in neonate's peripheral blood (−6.94%; 95% CI, −9.15% to −4.73%) was substantially lower than that in cord blood (−1.75%; 95% CI, −2.82%, −0.68%) (P value for testing subgroup differences <0.001). In conclusion, cesarean section compared with vaginal delivery is associated with a reduced placental transfusion and poor iron-related hematologic indices in both cord and peripheral blood, indicating that neonates delivered by cesarean section might be more likely affected by iron-deficiency anemia in infancy.