- attending physician estimation (< 50% likelihood) of other more likely non-covid etiology - presence of tracheostomy - requirement of oxygen therapy to maintain resting oxygen saturation of > 94% - clinical contraindication to use of inhaled nitric oxide

- attending physician estimation (< 50% likelihood) of other more likely non-covid etiology - presence of tracheostomy - requirement of oxygen therapy to maintain resting oxygen saturation of > 94% - clinical contraindication to use of inhaled nitric oxide