Hypothermia-Induced Platelet Aggregation: No Effect of Aprotinin (Trasylol®) but Inhibition by Eptifibatide (Integrilin®)

An Exploratory Analysis of Gastrointestinal Morbidities and Feeding Outcomes Associated with Neonatal Hypoxic-Ischemic Encephalopathy With or Without Hypothermia Therapy

This study investigates the clinical profile and predictors of gastrointestinal/hepatic morbidities and feeding outcomes among neonates with hypoxic-ischemic encephalopathy (HIE). A single-center retrospective chart review of consecutive neonates >35 weeks of gestation admitted with a diagnosis of HIE between January 1, 2015, and December 31, 2020, and treated with therapeutic hypothermia, if met the institutional eligibility criteria. Outcomes assessed included necrotizing enterocolitis (NEC), conjugated hyperbilirubinemia, hepatic dysfunction, assisted feeding at discharge, and time to reach full enteral and oral feeds. Among 240 eligible neonates (gestational age 38.7 [1.7] weeks, birth weight 3279 [551] g), 148 (62%) received hypothermia therapy, and 7 (3%) and 5 (2%) were diagnosed with stage 1 NEC and stage 2-3 NEC, respectively. Twenty-nine (12%) were discharged home with a gastrostomy/gavage tube, conjugated hyperbilirubinemia (first week 22 [9%], at discharge 19 [8%]), and hepatic dysfunction (74 [31%]). Time to reach full oral feeds was significantly longer in hypothermic neonates compared with neonates who did not receive hypothermia (9 [7-12] days vs. 4.5 [3-9] days, p < 0.0001). Factors significantly associated with NEC were renal failure (odds ratio [OR] 9.24, 95% confidence interval [CI] 2.7-33), hepatic dysfunction (OR 5.69, 95% CI 1.6-26), and thrombocytopenia (OR 3.6, 95% CI 1.1-12), but no significant association with hypothermia, severity of brain injury, or stage of encephalopathy. Transient conjugated hyperbilirubinemia, hepatic dysfunction within first week of life, and need for assistive feeding are more common than NEC in HIE. Risk of NEC was associated with the severity of end-organ dysfunction in the first week of life, rather than severity of brain injury and hypothermia therapy per se.

Bleeding Following Deep Hypothermia and Circulatory Arrest in Children

Deep hypothermic circulatory arrest (DHCA) is a technique of extracorporeal circulation commonly used in children with complex congenital heart defects undergoing surgical repairs. The use of profound cooling (20°C) and complete cessation of circulation allow adequate exposure and correction of these complex lesions, with enhanced cerebral protection. However, the profound physiologic state of DHCA results in significant derangement of the coagulation system and a high incidence of postoperative bleeding. This review examines the impact of DHCA on bleeding and transfusion requirements in children and the pathophysiology of DHCA-induced platelet dysfunction. It also focuses on possible pharmacologic interventions to decrease bleeding following DHCA in children.

Aprotinin in cardiac surgery

Aprotinin is a naturally occurring serine protease inhibitor that is being used with increasing frequency in cardiac surgery and beyond to reduce blood loss and the need for perioperative blood transfusion. Through inhibition of serine proteases such as plasmin, aprotinin significantly reduces fibrinolysis, thereby aiding hemostasis during surgical procedures. In addition, aprotinin interacts with other factors in the coagulation and fibrinolytic cascade, creating a hemostatic balance, without increasing the risk of thrombosis. These proven benefits are supplemented by the anti-inflammatory properties of aprotinin, which may help curb some of the deleterious effects of cardiopulmonary bypass. This article will review the discovery of aprotinin, its mechanism of action, dosing and adverse effects, and highlight the major recent trials demonstrating its efficacy.

Blood cell dynamics during hibernation in the European Ground Squirrel

Hibernation is a unique natural model to study large and specific modulation in numbers of leukocytes and thrombocytes, with potential relevance for medical application. Hibernating animals cycle through cold (torpor) and warm (arousal) phases. Previous research demonstrated clearance of leukocytes and thrombocytes from the circulation during torpor, but did not provide information regarding the timing during torpor or the subtype of leukocytes affected. To study the influence of torpor-bout duration on clearance of circulating cells, we measured blood cell dynamics in the European Ground Squirrel. Numbers of leukocytes and thrombocytes decreased within 24h of torpor by 90% and remained unchanged during the remainder of the torpor-bout. Differential counts demonstrated that granulocytes, lymphocytes and monocytes are all affected by torpor. Although a decreased production might explain the reduced number of thrombocytes, granulocytes and monocytes, this cannot explain the observed lymphopenia since lymphocytes have a much lower turnover rate than thrombocytes, granulocytes and monocytes. In conclusion, although underlying biochemical signaling pathways need to be unraveled, our data show that the leukocyte count drops dramatically after entrance into torpor and that euthermic cell counts are restored within 1.5h after onset of arousal, even before body temperature is fully normalized.