Viscoelastic coagulation testing in Neonatal Intensive Care Units: advantages and pitfalls in clinical practice.

The expression "developmental hemostasis" indicates the age-related physiological changes occurring during the maturational process of the hemostatic system. Despite the quantitative and qualitative alterations, the neonatal hemostatic system is competent and well-balanced. Conventional coagulation tests do not provide reliable information as they only explore the procoagulants during the neonatal period. In contrast, viscoelastic coagulation tests (VCTs), such as viscoelastic coagulation monitoring (VCM), thromboelastography (TEG or ClotPro), and rotational thromboelastometry (ROTEM), are point-of-care assays that provide a quick, dynamic and global view of the hemostatic process, allowing prompt and individualized therapeutic intervention when necessary. Their use in neonatal care is on the increase and they could help monitor patients at risk of hemostatic derangement. In addition, they are crucial for anticoagulation monitoring during extracorporeal membrane oxygenation. Moreover, implementing VCT-based monitoring could optimize blood product use.

Hemostasis in neonatal ECMO.

Extracorporeal membrane oxygenation (ECMO) is a life-saving support for cardio-respiratory function. Over the last 50 years, the extracorporeal field has faced huge technological progress. However, despite the improvements in technique and materials, coagulation problems are still the main contributor to morbidity and mortality of ECMO patients. Indeed, the incidence and survival rates of the main hemorrhagic and thrombotic complications in neonatal respiratory ECMO are relevant. The main culprit is related to the intrinsic nature of ECMO: the contact phase activation. The exposure of the human blood to the non-endothelial surface triggers a systemic inflammatory response syndrome, which chronically activates the thrombin generation and ultimately leads to coagulative derangements. Pre-existing illness-related hemostatic dysfunction and the peculiarity of the neonatal clotting balance further complicate the picture. Systemic anticoagulation is the management's mainstay, aiming to prevent thrombosis within the circuit and bleeding complications in the patient. Although other agents (i.e., direct thrombin inhibitors) have been recently introduced, unfractionated heparin (UFH) is the standard of care worldwide. Currently, there are multiple tests exploring ECMO-induced coagulopathy. A combination of the parameters mentioned above and the evaluation of the patient's underlying clinical context should be used to provide a goal-directed antithrombotic strategy. However, the ideal algorithm for monitoring anticoagulation is currently unknown, resulting in a large inter-institutional diagnostic variability. In this review, we face the features of the available monitoring tests and approaches, mainly focusing on the role of point-of-care (POC) viscoelastic assays in neonatal ECMO. Current gaps in knowledge and areas that warrant further study will also be addressed.

Veno-Arterial Extracorporeal Membrane Oxygenation (ECMO) Impairs Bradykinin-Induced Relaxation in Neonatal Porcine Coronary Arteries.

Extracorporeal membrane oxygenation (ECMO) is a lifesaving support for respiratory and cardiovascular failure. However, ECMO induces a systemic inflammatory response syndrome that can lead to various complications, including endothelial dysfunction in the cerebral circulation. We aimed to investigate whether ECMO-associated endothelial dysfunction also affected coronary circulation. Ten-day-old piglets were randomized to undergo either 8 h of veno-arterial ECMO (n = 5) or no treatment (Control, n = 5). Hearts were harvested and coronary arteries were dissected and mounted as 3 mm rings in organ baths for isometric force measurement. Following precontraction with the thromboxane prostanoid (TP) receptor agonist U46619, concentration−response curves to the endothelium-dependent vasodilator bradykinin (BK) and the nitric oxide (NO) donor (endothelium-independent vasodilator) sodium nitroprusside (SNP) were performed. Relaxation to BK was studied in the absence or presence of the NO synthase inhibitor Nω-nitro-L-arginine methyl ester HCl (L-NAME). U46619-induced contraction and SNP-induced relaxation were similar in control and ECMO coronary arteries. However, BK-induced relaxation was significantly impaired in the ECMO group (30.4 ± 2.2% vs. 59.2 ± 2.1%; p < 0.0001). When L-NAME was present, no differences in BK-mediated relaxation were observed between the control and ECMO groups. Taken together, our data suggest that ECMO exposure impairs endothelium-derived NO-mediated coronary relaxation. However, there is a NO-independent component in BK-induced relaxation that remains unaffected by ECMO. In addition, the smooth muscle cell response to exogenous NO is not altered by ECMO exposure.

Proinflammatory Endothelial Phenotype in Very Preterm Infants: A Pilot Study.

Very preterm infants are exposed to prenatal inflammatory processes and early postnatal hemodynamic and respiratory complications, but limited data are available about the endothelial effect of these conditions. The present pilot study investigates the perinatal endothelial phenotype in very preterm infants (VPIs) and explores its predictive value on neonatal mortality and hemodynamic and respiratory complications. Angiopoietin 1 (Ang-1), Ang-2, E-selectin, vascular adhesion molecule 1 (VCAM-1), tissue factor (TF), and endothelin 1 (ET-1) concentrations were tested in first (T1), 3rd (T2), and 7-10th (T3) day of life in 20 VPIs using Luminex technology and compared with 14 healthy full-term infants (FTIs). Compared to FTIs, VPIs had lower Ang-1 at T1 and T2; higher Ang-2 at T1, T2, and T3; higher Ang-2/Ang-1 ratio at T1, T2, and T3; lower E-selectin at T1, T2, and T3; higher VCAM-1 at T1; higher TF at T2. No differences in concentrations were found in neonatal deaths. VPIs with hemodynamic or respiratory complications had higher Ang-2 at T3. Perinatal low Ang-1 and high Ang-2 associated with high VCAM-1 and TF in VPIs suggest a proinflammatory endothelial phenotype, resulting from the synergy of a pathological prenatal inheritance and a premature extrauterine transition.

Individualized Bleeding Risk Assessment through Thromboelastography: A Case Report of May-Hegglin Anomaly in Preterm Twin Neonates.

May-Hegglin anomaly (MHA) is a rare autosomal dominant disorder in the spectrum of myosin heavy chain-related disorders (MYH9-RD), characterized by congenital macrothrombocytopenia and white blood cell inclusions. MHA carries a potential risk of hemorrhagic complications. Bleeding diathesis is usually mild, but sporadic, life-threatening events have been reported. Data regarding the clinical course and outcomes of neonatal MYH9-RD are limited, and specific guidelines on platelet transfusion in asymptomatic patients are lacking. We present monochorionic twins born preterm at 32 weeks of gestation to an MHA mother; both presented with severe thrombocytopenia at birth. Peripheral blood smear demonstrated the presence of macrothrombocytes, and immunofluorescence confirmed the diagnosis of MHA. Close clinical monitoring excluded bleeding complications, and serial hemostatic assessments through a viscoelastic system demonstrated functionally normal primary hemostasis in both patients. Therefore, prophylactic platelet transfusions were avoided. Whole DNA sequencing confirmed the pathogenetic variant of MHA of maternal origin in both twins. Thromboelastography allowed real-time bedside bleeding risk assessment and supported individualized transfusion management in preterm newborns at risk of hemostatic impairment. This report suggests that dynamic and appropriate clotting monitoring may contribute to the more rational use of platelets' transfusions while preserving patients with hemorrhagic complications and potential transfusion-related side effects.

D-lactic acidosis in humans: systematic literature review.

BACKGROUND: D-lactic acidosis is an uncommon and challenging form of metabolic acidosis that may develop in short bowel syndrome. It has been documented exclusively in case reports and small case series. METHODS: We performed a review of the literature in the National Library of Medicine and Excerpta Medica databases. RESULTS: We identified 84 original reports published between 1977 and 2017. D-lactic acidosis was observed in 98 individuals ranging in age from 7 months to 86 years with short bowel syndrome. The clinical presentation included Kussmaul breathing, confusion, slurred speech, and gait disturbances. Furthermore, among 99 consecutive patients with short bowel syndrome, 21 reported having episodes with symptoms consistent with D-lactic acidosis. In addition, D-lactic acid might also contribute to acidosis in diabetes mellitus. Finally, abnormally high D-lactic acid was documented after administration or ingestion of large amounts of propylene glycol, as paraneoplastic phenomenon and perhaps also in a so far poorly characterized inherited inborn error of metabolism. CONCLUSIONS: In humans with short bowel syndrome (or carbohydrate malabsorption), D-lactic acidosis is likely rather common and under-recognized. This condition should be included in the differential diagnosis of unexplained high-gap metabolic acidosis where the anion causing the acidosis is not known. Furthermore, diabetic acidosis might be caused by accumulation of both ketone bodies and D-lactic acid. Finally, there are endogenous sources of D-lactic acid in subjects with propylene glycol intoxication.