Problem
A Caucasian male weighing 4950 g, born of vaginal delivery at 40 weeks' gestation, presented with severe respiratory insufficiency due to meconium aspiration syndrome (MAS). He was immediately transferred to the neonatal intensive care unit for supportive care. There he was treated for a left-sided pneumothorax with a water-sealed chest tube. He was intubated and received mechanical ventilation on the following settings: peak inspiratory pressure 25 cm H2O, PEEP 8 cm H2O, mandatory rate 60 breaths per minute, inspiratory time 0.4 seconds, and FiO2 1.0. The mean airway pressure was measured at 20 mm Hg. Arterial gas analysis showed the following: pH 7.29, PaO2 39.4 torr, PaCO2 52.7 torr, HCO3 24.5 mEq/L, BE -1.5, and oxygen saturation 84%. The echocardiogram showed severe pulmonary hypertension. Inhaled nitric oxide was started at 20 ppm. Cranial ultrasound scanning and blood coagulation tests yielded normal results. Dopamine and dobutamine were administered due to low blood pressure and impaired peripheral perfusion. After 12 hours of treatment, a number of ventilator changes were made to improve respiratory status, and inhaled nitric oxide was increased to 30 ppm, but there was no improvement of the patient's respiratory status. Because no improvement in oxygenation or ventilation occurred, ECMO was considered. Venous-arterial ECMO by roller pump was initiated. The initial ECMO flow was 120 cc/kg and was reduced according to the child's tolerance. The objective was to maintain a PaO2 between 70 and 90 torr and a PaCO2 between 40 and 50 torr. Mechanical ventilator settings were minimal to rest the lungs. The patient received ECMO for 6 days, was successfully weaned from ECMO support, and discharged home a month later.
a) List two clinical conditions of the newborn that may be unresponsive to standard treatment.
b) Calculate the oxygenation index (OI) for this patient.
c) Describe the two types of ECMO circuits and systems.