Effect of body position and ventilation on umbilical artery and venous blood flows during delayed umbilical cord clamping in preterm lambs.
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SUBMITTER: Hooper SB
PROVIDER: S-EPMC5537513 | biostudies-other | 2017 Jul
REPOSITORIES: biostudies-other
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Project description:BackgroundDelayed umbilical cord clamping (UCC) after birth is thought to cause placental to infant blood transfusion, but the mechanisms are unknown. It has been suggested that uterine contractions force blood out of the placenta and into the infant during delayed cord clamping. We have investigated the effect of uterine contractions, induced by maternal oxytocin administration, on umbilical artery (UA) and venous (UV) blood flows before and after ventilation onset to determine whether uterine contractions cause placental transfusion in preterm lambs.Methods and findingsAt ~128 days of gestation, UA and UV blood flows, pulmonary arterial blood flow (PBF) and carotid arterial (CA) pressures and blood flows were measured in three groups of fetal sheep during delayed UCC; maternal oxytocin following mifepristone, mifepristone alone, and saline controls. Each successive uterine contraction significantly (p<0.05) decreased UV (26.2±6.0 to 14.1±4.5 mL.min-1.kg-1) and UA (41.2±6.3 to 20.7 ± 4.0 mL.min-1.kg-1) flows and increased CA pressure and flow (47.1±3.4 to 52.8±3.5 mmHg and 29.4±2.6 to 37.3±3.4 mL.min-1.kg-1). These flows and pressures were partially restored between contractions, but did not return to pre-oxytocin administration levels. Ventilation onset during DCC increased the effects of uterine contractions on UA and UV flows, with retrograde UA flow (away from the placenta) commonly occurring during diastole.ConclusionsWe found no evidence that amplification of uterine contractions with oxytocin increase placental transfusion during DCC. Instead they decreased both UA and UV flow and caused a net loss of blood from the lamb. Uterine contractions did, however, have significant cardiovascular effects and reduced systemic and cerebral oxygenation.
| S-EPMC8211207 | biostudies-literature
Project description:BACKGROUND AND OBJECTIVE:Delayed cord clamping (DCC) is recommended for premature infants to improve blood volume. Most preterm infants are born by cesarean delivery (CD), and placental transfusion may be less effective than in vaginal delivery (VD). We sought to determine whether infants <32 weeks born by CD who undergo umbilical cord milking (UCM) have higher measures of systemic blood flow than infants who undergo DCC. METHODS:This was a 2-center trial. Infants delivered by CD were randomly assigned to undergo UCM or DCC. Infants delivered by VD were also randomly assigned separately. UCM (4 strippings) or DCC (45-60 seconds) were performed. Continuous hemodynamic measurements and echocardiography were done at site 1. RESULTS:A total of 197 infants were enrolled (mean gestational age 28 ± 2 weeks). Of the 154 infants delivered by CD, 75 were assigned to UCM and 79 to DCC. Of the infants delivered by CD, neonates randomly assigned to UCM had higher superior vena cava flow and right ventricular output in the first 12 hours of life. Neonates undergoing UCM also had higher hemoglobin, delivery room temperature, blood pressure over the first 15 hours, and urine output in the first 24 hours of life. There were no differences for the 43 infants delivered by VD. CONCLUSIONS:This is the first randomized controlled trial demonstrating higher systemic blood flow with UCM in preterm neonates compared with DCC. UCM may be a more efficient technique to improve blood volume in premature infants delivered by CD.
| S-EPMC4485011 | biostudies-literature
Project description:BackgroundUmbilical cord milking (UCM) at birth causes surges in arterial blood pressure and blood flow to the brain, which may explain the high risk of intraventricular haemorrhage (IVH) in extremely preterm infants receiving UCM. This high risk of IVH has not been reported in older infants.ObjectiveWe hypothesized that lung aeration before UCM, reduces the surge in blood pressure and blood flow induced by UCM.MethodsAt 126 days' gestation, fetal lambs (N = 8) were exteriorised, intubated and instrumented to measure umbilical, pulmonary, cerebral blood flows, and arterial pressures. Prior to ventilation onset, the umbilical cord was briefly (2-3 s) occluded (8 times), which was followed by 8 consecutive UCMs when all physiological parameters had returned to baseline. Lambs were then ventilated. After diastolic pulmonary blood flow markedly increased in response to ventilation, the lambs received a further 8 consecutive UCMs. Ovine umbilical cord is shorter than the human umbilical cord, with ∼10 cm available for UCMs. Therefore, 8 UCMs/occlusions were done to match the volume reported in the human studies. Umbilical cord clamping occurred after the final milk.ResultsBoth umbilical cord occlusions and UCM caused significant increases in carotid arterial blood flow and pressure. However, the increases in systolic and mean arterial blood pressure (10 ± 3 mmHg vs. 3 ± 2 mmHg, p = 0.01 and 10 ± 4 mmHg vs. 6 ± 2 mmHg, p = 0.048, respectively) and carotid artery blood flow (17 ± 6 ml/min vs. 10 ± 6 ml/min, p = 0.02) were significantly greater when UCM occurred before ventilation onset compared with UCM after ventilation.ConclusionsUCM after ventilation onset significantly reduces the increases in carotid blood flow and blood pressure caused by UCM.
| S-EPMC10071016 | biostudies-literature
Project description:ImportanceUmbilical cord milking as an alternative to delayed umbilical cord clamping may provide equivalent benefits to preterm infants, but without delaying resuscitation.ObjectiveTo determine whether the rates of death or severe intraventricular hemorrhage differ among preterm infants receiving placental transfusion with umbilical cord milking vs delayed umbilical cord clamping.Design, setting, and participantsNoninferiority randomized clinical trial of preterm infants (born at 23-31 weeks' gestation) from 9 university and private medical centers in 4 countries were recruited and enrolled between June 2017 and September 2018. Planned enrollment was 750 per group. However, a safety signal comprising an imbalance in the number of severe intraventricular hemorrhage events by study group was observed at the first interim analysis; enrollment was stopped based on recommendations from the data and safety monitoring board. The planned noninferiority analysis could not be conducted and a post hoc comparison was performed instead. Final date of follow-up was December 2018.InterventionsParticipants were randomized to umbilical cord milking (n = 236) or delayed umbilical cord clamping (n = 238).Main outcomes and measuresThe primary outcome was a composite of death or severe intraventricular hemorrhage to determine noninferiority of umbilical cord milking with a 1% noninferiority margin.ResultsAmong 540 infants randomized, 474 (88%) were enrolled and completed the trial (mean gestational age of 28 weeks; 46% female). Twelve percent (29/236) of the umbilical cord milking group died or developed severe intraventricular hemorrhage compared with 8% (20/238) of the delayed umbilical cord clamping group (risk difference, 4% [95% CI, -2% to 9%]; P = .16). Although there was no statistically significant difference in death, severe intraventricular hemorrhage was statistically significantly higher in the umbilical cord milking group than in the delayed umbilical cord clamping group (8% [20/236] vs 3% [8/238], respectively; risk difference, 5% [95% CI, 1% to 9%]; P = .02). The test for interaction between gestational age strata and treatment group was significant for severe intraventricular hemorrhage only (P = .003); among infants born at 23 to 27 weeks' gestation, severe intraventricular hemorrhage was statistically significantly higher with umbilical cord milking than with delayed umbilical cord clamping (22% [20/93] vs 6% [5/89], respectively; risk difference, 16% [95% CI, 6% to 26%]; P = .002).Conclusions and relevanceIn this post hoc analysis of a prematurely terminated randomized clinical trial of umbilical cord milking vs delayed umbilical cord clamping among preterm infants born at less than 32 weeks' gestation, there was no statistically significant difference in the rate of a composite outcome of death or severe intraventricular hemorrhage, but there was a statistically significantly higher rate of severe intraventricular hemorrhage in the umbilical cord milking group. The early study termination and resulting post hoc nature of the analyses preclude definitive conclusions.Trial registrationClinicalTrials.gov Identifier: NCT03019367.
| S-EPMC6865839 | biostudies-literature
Project description:BackgroundDelayed cord clamping (DCC) is a placental to new-born transfusion strategy recommended by obstetric and gynaecological societies. Though not widely adopted, umbilical cord milking (UCM) may achieve faster transfusion when DCC cannot be performed such as when a neonate requires resuscitation.MethodsPragmatic, two-arm, randomized clinical trial in which consenting women in spontaneous labour or provider-initiated delivery at 28 to less than 37 weeks at Kenyatta National Hospital in Nairobi, Kenya, were enrolled. At delivery, stable preterm infants were randomized to UCM (4 times) or DCC (60 seconds). Neonatal samples were collected for analysis at 24 hours after delivery. Maternal primary PPH (within 24 hours) and neonatal jaundice (within 1 week) were evaluated clinically. The primary outcome was the mean neonatal haemoglobin level at 24 hours after birth. Modified Intention to treat analysis was used for all outcomes. P-value was significant at p<0.05.ResultsBetween March 2018 to March 2019, 344 pregnant women underwent screening, and 280 eligible participants were randomized when delivery was imminent. The intervention was not performed on 19 ineligible neonates. Of the remaining 260 neonates, 133 underwent UCM while 128 underwent DCC. Maternal and neonatal baseline characteristics were similar. The mean neonatal haemoglobin (17.1 vs 17.5 grams per decilitre, p = 0.191), haematocrit (49.6% vs 50.3%, p = 0.362), anaemia (9.8% vs 11.7%, p = 0.627), maternal PPH (2.3% vs 3.1%, p = 0.719) were similar between UCM and DCC respectfully. However, neonatal polycythaemia (2.3% vs 8.6%, p = 0.024) and neonatal jaundice (6.8% vs 15.6%, p = 0.024) were statistically significantly lower in UCM compared to DCC.ConclusionUCM compared to DCC for preterm neonates resulted in similar outcomes for neonatal haemoglobin, haematocrit, anaemia and maternal primary PPH and a lower proportion of neonatal polycythaemia and clinical jaundice. UCM offers a comparable method of placental transfusion compared to DCC and may be considered as an alternative to DCC in preterm neonates at 28 to <37 weeks' gestation.
| S-EPMC7837492 | biostudies-literature
Project description:ObjectiveTo evaluate changes in cerebral oxygenation, peripheral arterial oxygenation, respiratory status, and administered fraction of inspired oxygen during the first 10 minutes of life in premature infants receiving umbilical cord milking compared with delayed cord clamping (DCC).Study designPremature infants born at 230/7 to 276/7 weeks of gestation were randomized to umbilical cord milking or DCC. A near infrared spectroscopy sensor, pulse oximeter, and electrocardiogram electrodes were placed. Pulse rate, cerebral tissue oxygenation, peripheral oxygen saturation, airway pressure, and fraction of inspired oxygen were collected for 10 minutes in the delivery room. Longitudinal models were used to compare effects of umbilical cord milking and DCC.ResultsFifty-six infants had cerebral oximetry and advanced monitoring at birth. There was an increased incidence of severe intraventricular hemorrhage in infants who received umbilical cord milking compared with DCC (P = .0211). Longitudinal models suggested that peripheral oxygen saturation was higher in the umbilical cord milking group in the first 4 minutes (P = .0221) and that mean airway pressures were lower in the umbilical cord milking group after the first 7 minutes (P = .0072). No statistical differences were observed for fraction of inspired oxygen, cerebral tissue oxygenation, or heart rates.ConclusionsThe data suggest that the rapid transfer of blood during umbilical cord milking may facilitate lung expansion with improved pulmonary blood flow, but may also increase cerebral blood flow, resulting in severe intraventricular hemorrhage.Trial registrationClinicalTrials.gov: NCT03145142.
| S-EPMC7387184 | biostudies-literature
Project description:Bronchopulmonary dysplasia (BPD) is a frequent cause of morbidity in preterm infants that is characterized by prolonged need for ventilatory support in an intensive care environment. BPD is characterized histopathologically by persistently thick, cellular distal airspace walls. In normally developing lungs, by comparison, remodeling of the immature parenchymal architecture is characterized by thinning of the future alveolar walls, a process predicated on cell loss through apoptosis.We hypothesized that minimizing lung injury, using high-frequency nasal ventilation to provide positive distending pressure with minimal assisted tidal volume displacement, would increase apoptosis and decrease proliferation among mesenchymal cells in the distal airspace walls compared with a conventional mode of support (intermittent mandatory ventilation).Accordingly, we compared two groups of preterm lambs: one group managed by high-frequency nasal ventilation and a second group managed by intermittent mandatory ventilation. Each group was maintained for 3 days.Oxygenation and ventilation targets were sustained with lower airway pressures and less supplemental oxygen in the high-frequency nasal ventilation group, in which alveolarization progressed. Thinning of the distal airspace walls was accompanied by more apoptosis, and less proliferation, among mesenchymal cells of the high-frequency nasal ventilation group, based on morphometric, protein abundance, and mRNA expression indices of apoptosis and proliferation.Our study shows that high-frequency nasal ventilation preserves the balance between mesenchymal cell apoptosis and proliferation in the distal airspace walls, such that alveolarization progresses.
| S-EPMC2542442 | biostudies-other
Project description:PurposeInjurious mechanical ventilation causes white matter (WM) injury in preterm infants through inflammatory and haemodynamic pathways. The relative contribution of each of these pathways is not known. We hypothesised that in vivo magnetic resonance imaging (MRI) can detect WM brain injury resulting from mechanical ventilation 24 h after preterm delivery. Further we hypothesised that the combination of inflammatory and haemodynamic pathways, induced by umbilical cord occlusion (UCO) increases brain injury at 24 h.MethodsFetuses at 124±2 days gestation were exposed, instrumented and either ventilated for 15 min using a high tidal-volume (VT) injurious strategy with the umbilical cord intact (INJ; inflammatory pathway only), or occluded (INJ+UCO; inflammatory and haemodynamic pathway). The ventilation groups were compared to lambs that underwent surgery but were not ventilated (Sham), and lambs that did not undergo surgery (unoperated control; Cont). Fetuses were placed back in utero after the 15 min intervention and ewes recovered. Twenty-four hours later, lambs were delivered, placed on a protective ventilation strategy, and underwent MRI of the brain using structural, diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS) techniques.ResultsAbsolute MRS concentrations of creatine and choline were significantly decreased in INJ+UCO compared to Cont lambs (P = 0.03, P = 0.009, respectively); no significant differences were detected between the INJ or Sham groups and the Cont group. Axial diffusivities in the internal capsule and frontal WM were lower in INJ and INJ+UCO compared to Cont lambs (P = 0.05, P = 0.04, respectively). Lambs in the INJ and INJ+UCO groups had lower mean diffusivities in the frontal WM compared to Cont group (P = 0.04). DTI colour mapping revealed lower diffusivity in specific WM regions in the Sham, INJ, and INJ+UCO groups compared to the Cont group, but the differences did not reach significance. INJ+UCO lambs more likely to exhibit lower WM diffusivity than INJ lambs.ConclusionsTwenty-four hours after injurious ventilation, DTI and MRS showed increased brain injury in the injuriously ventilated lambs compared to controls. DTI colour mapping threshold approach provides evidence that the haemodynamic and inflammatory pathways have additive effects on the progression of brain injury compared to the inflammatory pathway alone.
| S-EPMC5718608 | biostudies-literature
Project description:Background: High frequency oscillatory ventilation (HFOV) is considered a lung protective ventilation mode in preterm infants only if lung volume is optimized. However, whilst a "high lung volume strategy" is advocated for HFOV in preterm infants this strategy is not precisely defined. It is not known to what extent lung recruitment should be pursued to provide lung protection. In this study we aimed to determine the relationship between the magnitude of lung volume optimization and its effect on gas exchange and lung injury in preterm lambs. Methods: 36 surfactant-deficient 124-127 d lambs commenced HFOV immediately following a sustained inflation at birth and were allocated to either (1) no recruitment (low lung volume; LLV), (2) medium- (MLV), or (3) high lung volume (HLV) recruitment strategy. Gas exchange and lung volume changes over time were measured. Lung injury was analyzed by post mortem pressure-volume curves, alveolar protein leakage, gene expression, and histological injury score. Results: More animals in the LLV developed a pneumothorax compared to both recruitment groups. Gas exchange was superior in both recruitment groups compared to LLV. Total lung capacity tended to be lower in the LLV group. Other parameters of lung injury were not different. Conclusions: Lung recruitment during HFOV optimizes gas exchange but has only modest effects on lung injury in a preterm animal model. In the HLV group aiming at a more extensive lung recruitment gas exchange was better without affecting lung injury.
| S-EPMC6349831 | biostudies-literature
Project description:BackgroundOptimum timing of umbilical cord clamping has not been established in preterm infants.ObjectivesWe compared the short- and long-term effects of umbilical cord milking (UCM) versus delayed cord clamping (DCC) on infants born at less than 37 weeks of gestation.Search methodsA systematic review and meta-analysis was conducted according to the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" statement. We searched CINAHL, CENTRAL, EMBASE, MEDLINE, PubMed and ClinicalTrials.gov for relevant randomized controlled trials (RCTs).Selection criteriaWe included individual and clustered RCTs comparing UCM to DCC for infants born before 37 weeks of gestation.Data collection and analysisFour reviewers independently assessed trial quality and eligibility for inclusion.Main resultsTwo trials (255 preterm infants, 23 0/7 to 32 6/7 weeks of gestation) were included in the analysis. UCM was associated with fewer intraventricular hemorrhages (IVHs) (two trials, 255 infants; relative risk [RR] 0.45, 95% confidence interval [CI] 0.20 to 0.98, low quality of evidence) and UCM was an increased proportion of infants with a Bayley score at 2 years of age (two trials, 174 infants; Cognitive: RR 1.14, 95% CI 1.03 to 1.26, Language: RR 1.24, 95% CI 1.03 to 1.49, low quality of evidence) compared to DCC.ConclusionsUCM wasn't reduced in-hospital mortality and need for transfusion compared to DCC. But our study suggests that UCM may lower the risk of IVH and improve certain neurodevelopmental outcomes compared to DCC in preterm infants.
| S-EPMC6116944 | biostudies-literature