In babies with hypoxic respiratory failure, blood vessels in the lungs are constricted limiting bloodflow from the heart to the lungs (termed ”pulmonary hypertension”). As a result, when blood low in oxygen returns to the heart, it bypasses the lungs through fetal channels and flows back out to the body (termed “extrapulmonary shunting”). When inhaled INOmax® causes the constricted lung vessels to relax resulting in an increase in blood flow from the heart to the lungs, and a decrease in the amount of blood that bypasses the lungs.
Many babies with hypoxic respiratory failure have patchy lung disease meaning there are areas in the lung with good airflow (and thus oxygen) and areas where there is little or no airflow. In areas of good airflow, gas exchange will occur readily – blood can pick up oxygen from the inhaled air and can offload carbon dioxide to be exhaled. In areas of poor or no airflow, gas exchange is not optimal and blood may pass through the lungs without picking up oxygen and delivering carbon dioxide (thermed “intrapulmonary shunt”). Because INOmax® is a gas and delivered to regions in the lungs in proportion to the degree of airflow, it causes a local degree in bloodflow in areas of the lung, where airflow is best and the best possible gas exchange can occur.
® INOmax is a trademark registered by AGA AB