Nasal cannula apparatus, includes in an inlet tubular fitting sized and configured to directly endwise connect to a source of oxygen, or oxygen and air. The fitting defines an inlet flow passage area A, having a 15 mm external diameter. A pair of tubular prongs is operatively connected with the inlet fitting, and receivable in an infant's nostrils to deliver oxygen, or oxygen and air flow to the infant, the prongs each having flow passing area A3, and A1>>A3.