**2. Asphyxia at birth**

Asphyxia at birth, also known as perinatal asphyxia, is the most common reason that newborn infants fail to make a successful transition to ex-utero life [10]. Asphyxia may occur from several perinatal events, such as failure of placental gas exchange prior to delivery (e.g. placental abruption, uterine rupture, umbilical cord prolapse, chorioamnionitis), or deficient pulmonary gas exchange immediately after birth (e.g. apnea, airway obstruction, respiratory distress syndrome) [10]. Asphyxia is a condition of impaired gas exchange with simultaneous hypoxia and hypercapnia, leading to a mixed metabolic and respiratory acidosis [10]; it depresses myocardial function leading to cardiogenic shock, pulmonary hypertension, mesenteric reperfusion, acute renal failure, and ultimately cardiac arrest. The cascade of hypoxic–ischemic insults results in dysfunction of one or more organ systems in over 80% of asphyxiated newborn infants [11], leading to significant mortality and long-term morbidity. Newborns affected by perinatal asphyxia often present with an inadequate heart rate that does not respond to positive pressure ventilation (PPV). This is due to depressed myocardial function, vasodilation, and very low diastolic blood pressures through which the heart is unable to efficiently contract. Ineffective pumping of enough blood to the lungs inhibits the exchange and consumption of oxygen that is being delivered via PPV [10]. This inevitably leads to the need for CC to mechanically pump the blood through the heart until the myocardium is adequately oxygenated to resume spontaneous contraction and blood circulation [10].
