Method and apparatus for ventilating a patient with a breathing gas mixture formed from nitric oxide, air, and oxygen

Abstract

A method and apparatus for supplying a breathing gas mixture to a patient in which a desired concentration of oxygen is maintained when nitric oxide (NO) is provided in the breathing gases. A clinician establishes at a ventilator, ventilation parameters for the patient, the inspired oxygen concentration, and the inspired NO dosage. From these quantities, a breathing gas mixture flow rate is determined. An instantaneous flow rate for an NO containing gas is determined, based on the concentration of nitric oxide in the supply gas and the instantaneous breathing gas mixture flow rate. An instantaneous flow rate for the supply of a balance gas, such as air, is determined using the breathing gas mixture flow rate, the instantaneous NO containing gas flow rate, and the inspired oxygen concentration established by the clinician. Finally, the instantaneous oxygen flow rate is determined as the difference between the inspiratory breathing gas flow rate and the instantaneous flow rates for the NO containing gas and the balance gas. A breathing gas mixture is thereafter provided to the patient at an instantaneous flow rate comprising the sum of the NO containing gas, balance gas, and oxygen flow rates. Actual gas flows are sensed by gas flow sensors and used to render the gas flow rates and the concentrations of NO and oxygen more accurate.

Dependencies are inferred from the claim text.