High-flow nasal oxygen therapy warms and humidifies gases, allows better clearance of secretions, along with providing added benefits like preventing dehydration of airway surface, while decreasing atelectasis and thereby, offering comfort to the patient. While its effect on critically ill patients is still in its pioneering phase, there is lack of substantial evidence on the use of high-flow nasal cannula in cardiac patients with type I respiratory failure. We found it worthwhile to share our experience of its use in elderly and postpartum patients with moderate-to-severe pulmonary hypertension, with associated comorbidities and type I respiratory failure, with do-not-intubate or defer intubation status. In patients with pulmonary hypertension (PHT) and respiratory failure, endotracheal intubation followed by initiation of mechanical ventilation may have detrimental hemodynamic effects. Increase in lung volumes and decrease in functional residual capacity lead to increase in pulmonary hypertension and right ventricle afterload. If a patient has right heart failure, lung hyperinflation can fatally reduce cardiac output. High-flow nasal oxygen therapy may be of an advantage in these scenarios.