Hyperoxia test algorithm: How will you carry out and interpret this test?

Hyperoxia test algorithm: How will you carry out and interpret this test?

Persistent pulmonary hypertension in the newborn can be sometimes very difficult to distinguish from true cyanotic congenital heart disease. Response to oxygen may also be sluggish, simulating cyanotic CHD. There can be a transient right to left shunt across PFO and PDA. Shunt across PDA in

this baby produced a differential saturation (>5% difference between radial and femoral samples).

ECG will often show RVH with strain and qR in V1 or V3 R, indicating suprasystemic PA pressure.

The clinical picture may simulate obstructed TAPVC, but chest X-ray (CXR) in TAPVC will be most often characteristic—“white wash lung”. If echo is not available, a modified hyperoxia test may pick up PPHN (see the flow chart).

Management is essentially supportive, by using oxygen, IV diuretics, sildenafil (IV or oral) and inotropes. Both dobutamine and milrinone are useful. Mechanical ventilation, nitric oxide (NO) inhalation and extracorporeal membrane oxygenation (ECMO) may be the other advanced options, if available.