Persistent Oxygen Requirement in Infants with Birth Asphyxia

Primary Pulmonary Causes

Periods of acute hypoxia are common causes of persistent pulmonary hypertension in infants with birth asphyxia, according to the American Heart Association 1, 2
Any disorder producing acute lung injury requiring positive-pressure mechanical ventilation and high oxygen concentrations during initial weeks of life predisposes infants to chronic lung disease of infancy (CLDI), as stated by the American Thoracic Society 3
Chronic alveolar hypoxia elicits pulmonary vasoconstriction leading to pulmonary hypertension, particularly in children with respiratory disorders, as reported by the American Thoracic Society 4
Intermittent hypoxemia adversely affects alveolar and vascular development in infants with BPD, according to the American Thoracic Society 4

Evaluation for structural airway abnormalities is essential, including tonsillar and adenoidal hypertrophy, vocal cord paralysis, subglottic stenosis, and tracheomalacia, as recommended by the American Heart Association 1, 2
Flexible bronchoscopy is required for diagnosis of anatomic and dynamic airway lesions that contribute to hypoxemia and poor clinical responses to oxygen therapy, according to the American Heart Association 1, 2
Tracheomalacia presents with wheezing and cyanosis with crying, as described by the American Thoracic Society 6

Infants with chronic lung disease from asphyxia may have deficient peripheral chemoreceptor function resulting from repeated and/or prolonged hypoxemia, as reported by the American Thoracic Society 7
Sixty percent of infants with CLDI lack a hyperoxic ventilatory response, with chemoreceptor activity negatively correlated with time spent on ventilator, according to the American Thoracic Society 7
Abnormal ventilatory and/or arousal responses during sleep contribute to persistent hypoxemia, as stated by the American Thoracic Society 7

Target oxygen saturations of 92% to 94% are sufficient to prevent adverse effects of hypoxia in most infants without increasing risk of additional lung inflammation and injury, as recommended by the American Heart Association 1, 2
Maintaining systemic oxygen saturation greater than 90% reduces frequency of central apnea and transient elevations in pulmonary artery pressure, according to the American Thoracic Society 9
Correction of hypoxemia using supplemental oxygen can ameliorate physiologic complications, with home oxygen therapy resolving right ventricular hypertrophy when SpO2 is maintained above 94-95%, as reported by the American Thoracic Society 4

Continuous oxygen saturation monitoring is essential; brief spot checks are insufficient for decisions on supplemental oxygen needs, as recommended by the American Heart Association 1, 2
Multiple determinations in various states including rest, sleep, feeding, and high activity are required, according to the American Thoracic Society 9
Echocardiogram and ECG are helpful when pulmonary hypertension is suspected, as stated by the American Thoracic Society 9
Serial echocardiograms should be performed at 4- to 6-month intervals depending on clinical course changes, as recommended by the American Heart Association 1, 2