Inhaled nitric oxide (iNO) administration in intubated and nonintubated patients: Delivery systems, interfaces, dose administration, and monitoring techniques

Inhaled nitric oxide (iNO) is a drug used to treat neonates with persistent pulmonary hypertension and as a rescue strategy for the treatment of severe hypoxemia. The clinical administration of iNO is challenging since the patient population is heterogeneous, ranging from critically ill patients intubated and mechanically ventilated to patients with chronic pulmonary hypertension receiving iNO at home [8]. In the intubated mechanically ventilated patients, airways are sealed by a cuffed endotracheal tube. Therefore, it is possible to precisely reach and maintain the target iNO concentration. Conversely, in nonintubated spontaneously breathing patients, the patient airways are not sealed by a cuffed endotracheal tube, so the instantaneous delivered dose cannot be accurately determined. A snug-fitting mask can be used to deliver NO as a patient interface in hospitalized patients with acute bacterial or viral pneumonia. In patients requiring long-term iNO administration, nasal cannula can be a suitable patient interface, which is also often used for long-term oxygen administration. To safely administer iNO, the continuous monitoring of the delivered NO and nitrogen dioxide (NO2) concentrations is recommended to avoid excessive NO2 delivery that is irritant for the airways. Further, blood oxygenation and methemoglobin concentration monitoring have to be considered during iNO administration to ensure an adequate tissue oxygenation.