title: Venous air emboli with 15N2: pulmonary excretion and physiologic responses in dogs.
abstract: Venous air embolism occurs with decompression sickness as well as during a wide variety of surgical procedures in hospitalized patients. We developed a canine model to allow documentation and quantitation of pulmonary excretion of intravascular air emboli both in a control air breathing state and during treatment. We utilized 15N2 (a stable, nonradioactive isotope of room air nitrogen, 14N2) as the nitrogen component of venous air emboli (1 ml.kg-1) given to 27 anesthetized mongrel dogs ventilated with room air (tidal volume = 15 ml.kg-1). End-tidal 15N2 was measured and the embolism diagnosed by increased levels in exhaled gases. Exhaled gases were also collected in Douglas bags and the 15N2 recovered was quantitated by a helium dilution technique. Systemic and pulmonary artery pressure changes and quantitation of excreted 15N2 were documented after embolism during a control state with continued room air (21% oxygen) ventilation, and after treatments with either a) 100% oxygen ventilation; b) compression to 2128 mmHg, or 2.8 atm abs, and room air ventilation; or c) a combination of 100% oxygen ventilation and 2.8 atm abs compression. Increased end-tidal 15N2 was characteristic of all emboli, and use of 15N2 allowed accurate measurement of excreted gas during both room air and 100% oxygen ventilation. Embolic gas recoveries were not increased significantly by any of the treatments.
authors.affiliation: Milton S. Hershey Medical Center, Penn State University, University Park 16802.
authors.forename: G B
authors.initials: GB
authors.lastname: Russell
authors.forename: M T
authors.initials: MT
authors.lastname: Snider
authors.forename: R B
authors.initials: RB
authors.lastname: Richard
authors.forename: J L
authors.initials: JL
authors.lastname: Loomis
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D004285:Dogs; D004618:Embolism, Air / Q000503:physiopathology / Q000628:therapy*; D009584:Nitrogen; D010100:Oxygen / Q000627:therapeutic use; D011651:Pulmonary Artery / Q000502:physiology; D011659:Pulmonary Gas Exchange; D014680:Veins
chemical_list: D009584:Nitrogen; D010100:Oxygen