Inhaled nitric oxide (iNO): Clinical applications in critical care medicine, delivery devices, and measuring techniques

Inhaled nitric oxide (iNO) is widely available for the treatment of multiple conditions such as hypoxemia due to pulmonary hypertension of the newborn (i.e., >34weeks of gestational age), acute respiratory distress syndrome, myocardial infarction, and it is under investigation as an antimicrobial agent. Other uses of iNO can be observed in the perioperative management of pulmonary hypertension in cardiac and transplantation surgery.With a wide range of doses from 1 up to 200ppm reported in the clinical setting, the care of the patient receiving iNO must include the monitoring of nitrogen dioxide (NO2) levels delivered to the patients and the methemoglobin concentration reached during the treatment together with the evaluation of the heart and the kidney functions.The methods primarily used to measure the amount of iNO delivered to the patient include absorbance, fluorescence, chemiluminescence-based approaches, electron paramagnetic resonance (EPR), and electrochemistry.Because of the cost and the organizational complexity of using NO stored in cylinders, iNO treatment is not available worldwide. However, a growing amount of evidence is exploring other methods to produce iNO (e.g., electric NO generators, chemical NO generators, NO-releasing solutions, and nanoparticles), making it more cost-efficient and potentially more available worldwide.