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Background: Oxygen delivery to the brain is dependent on cardiac output and arterial oxygen content. Objectives: The study was designed to investigate the influence of a left-to-right shunt via the ductus arteriosus (DA) on regional oxygen saturation (rSO2) of the brain and peripheral tissue during postnatal transition. Methods: Nested case-control study. In term neonates after elective cesarian section, rSO2 of the brain and pre- and postductal peripheral tissue were measured 15 min after uncomplicated postnatal transition. Two groups were formed according to shunt flow characteristics via the DA: shunt group (with a left-to-right shunt), and nonshunt group (no shunt). Results: Of 80 infants, in 58 (72%) a left-to-right shunt was identified, and in 22 (28%) no flow was seen via the DA. The 22 infants formed the nonshunt group. They were matched with 22 newborn infants with a left-to-right shunt via the DA (shunt group). Infants in the nonshunt group had significantly lower cerebral rSO2 values and higher fractional tissue oxygen extraction and heart rate values. There were no significant differences in regard to peripheral rSO2 values. Conclusion: During postnatal transition, term infants with a left-to-right shunt via the DA have significantly higher cerebral rSO2 values compared to infants without shunt flow.

Background: To date, only few pharmacokinetic studies on low-molecular-weight heparins (LMWHs) in neonates exist not allowing to formally assess pharmacodynamics of LMWHs in neonates. Objective: To evaluate the anticoagulant effects of the two LMWHs nadroparin and enoxaparin on endogenous formation of FXa or FIIa in cord versus adult platelet-poor plasma (PPP) and on thrombelastometry profiles in cord versus adult whole blood (WB). Unfractionated heparin (UH) was the reference antithrombotic drug. Methods: The effects of nadroparin, enoxaparin, or UH on endogenous formation of FXa or FIIa was investigated in tissue factor-activated PPP using a subsampling technique and chromogenic substrates. The anticoagulant efficacy of these drugs was also investigated in WB triggered by the physiological relevant activator collagen/endogenous thrombin using thrombelastometry. Results: The major findings are (i) nadroparin is as efficient as enoxaparin concerning inhibition of the endogenous formation of FXa and FIIa, (ii) cord PPP and WB are significantly more susceptible to the addition of LMWHs or UH than adult PPP or WB, and (iii) compared by equivalent anti-FXa activity, the anticoagulant action of UH is markedly higher than that of the LMWHs in PPP and WB of neonatal or adult origin. Conclusions: Administration of LMWHs in neonates has to be performed carefully to avoid bleeding side effects due to their high anticoagulant efficacy in cord PPP and WB.

Background: In previous studies, neonatal platelets have been shown to be hypoaggregable to various agonists when compared with adult platelets. Objectives: It was the aim of this study to investigate the aggregability of neonatal versus adult platelets when the physiological relevant agonist collagen/endogenous thrombin is used. Methods and Results: Whole blood (WB) aggregation experiments employing the impedance method revealed the same responsiveness of neonatal and adult platelets to collagen/endogenous thrombin. Maximum aggregation (13.5 ± 3.2 vs. 13.6 ± 3.2 Ω; p = 0.94), slope (5.8 ± 1.8 vs. 6.2 ± 2.6 Ω/min; p = 0.79) and lag time until the onset of platelet aggregation (38.7 ± 8.9 vs. 42.6 ± 16.5 s; p = 0.59) were similar in cord and adult WB. However, the rise in serotonin plasma levels due to platelet activation was significantly lower in neonates versus adults (227.57 ± 57.65 vs. 473.34 ± 155.75 ng/ml; p = 0.0001). Furthermore, we found a fast capability of cord plasma to generate (the efficient platelet agonist) endogenous thrombin: thrombin generation started significantly earlier in cord compared with adult plasma (215 ± 19 vs. 247 ± 21 s; p = 0.01). Moreover, thrombelastometry revealed significantly shorter coagulation times in cord versus adult WB activated with collagen/endogenous thrombin (229.8 ± 12.5 vs. 256.3 ± 25.3 s; p = 0.003). Conclusions: The efficient platelet aggregation in cord WB provoked by collagen/endogenous thrombin might help to explain the clinically observed well-functioning primary hemostasis of neonates.