Myocardial injury and performance in hypoxaemic neonates: Effects of oxygen and carbon dioxide during reoxygenation : An experimental study in newborn pigs
Year: 2005
Type: dissertation
Abstract: Definition of asphyxia.\nAsphyxia is a Greek term and means loss of pulse (1). There is no clear definition of the term, though perinatal asphyxia or birth asphyxia often is defined as impaired placental- or pulmonary oxygen delivery to the neonate. As a consequence the neonate is going through a period of hypoxaemia and hypercapnia with a subsequent respiratory and metabolic acidosis (1). In clinical work, the diagnosis of perinatal asphyxia predominantly is based on its consequences, and there is a general agreement that a combination of perinatal stress (i.e. fetal bradycardia, acidosis, low Apgar scores), multiple organ affection and neurological symptoms (i.e. hypoxic ischemic encephalopathy) are required for the diagnosis (2).\nCardiac abnormalities in perinatal asphyxia. \nMyocardial performance may vary subsequent to asphyxia. The cardiac dysfunction is often underdiagnosed and requires a high index of suspicion to detect (3;4). The clinical picture varies from brady- or tachycardia to cardiogenic shock (1;5). \nMyocardial failure subsequent to asphyxia was first reported in 1961 (6). The authors described a group of asphyxiated neonates with left ventricular (LV) heart failure within the first 24 hours of life. A decade later three term infants were reported with a syndrome of acute LV failure accompanied by cyanosis and pulmonary and systemic venous congestion (7). Rowe et al. (8) classified the cardiac abnormalities following asphyxia in 1978, broadly as:\n1) Transient myocardial ischaemia of the newborn\n2) Transient mitral regurgitation of the newborn\n3) Transient tricuspid regurgitation of the newborn\n4) Persistent pulmonary hypertension of the newborn\nIncreased pulmonary artery pressure (PAP) and tricuspid regurgitation is the most common, and although the cardiac abnormalities were described as separate clinical entities, it is important to understand that the distinction may not be clear, and there is much overlap in the pathogenesis. In severely asphyxiated neonates post-mortem autopsies have showed ischemic papillary muscle necrosis and diffuse subendocardial left ventricular (LV) necrosis secondary\nto perinatal asphyxia (9;10).\nAetiology\nThe aetiology of asphyxia in the newborn is multifactorial, including abruption or infarction of the placenta, excessive uterine contraction, fetal or maternal bleeding, and compression of the umbilical cord. Infection is contributing to its severity, and the clinical picture in severe asphyxia may present similar to what is seen in severe congenital heart disease, thus it is mandatory to evaluate these neonates by echocardiography to exclude congenital heart disease.
Author: Wenche Bakken Børke
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2276457729