title: A pressurized injection/suction system for ventilation in the presence of complete airway obstruction.
abstract: OBJECTIVE
  To describe the design and ventilatory characteristics of a new mode of ventilation (pressurized injection/suction ventilation).
  
  
  METHODS
  Descriptive and analytical laboratory study.
  
  
  METHODS
  Laboratory study.
  
  
  METHODS
  Simulated lung model and dogs.
  
  
  METHODS
  We tested the ability to maintain ventilation through a 2.5-mm internal diameter ventilating stylet in the setting of simulated complete airway occlusion. A microprocessor-controlled ventilator mode was used wherein injection of oxygen under high pressure (flow rate 95 L/min) alternates with suction of expired gas (flow rate 18 L/min) through the ventilating stylet.
  
  
  RESULTS
  In a lung model, we achieved a maximum minute ventilation of 12.9 L/min. In two dogs, we maintained stable oxygenation (mean PaO2 603 +/- 47 torr [80.4 +/- 6.3 kPa]) and ventilation (mean PaCO2 19 +/- 3 torr [2.5 +/- 0.4 kPa]) for 15 mins at maximum minute ventilation settings. No clinically important deleterious effects on the tracheal mucosa were observed. The ventilator system's safety-abort feature prevented overinflation or excessive deflation of the dogs' lungs in every test of simulated malfunction of the pressure-monitoring mechanism.
  
  
  CONCLUSIONS
  Pressurized injection/suction ventilation can maintain adequate gas exchange in an animal model with near-complete airway obstruction. Further work is needed to develop the safety and clinical applications of pressurized injection/suction ventilation in the management of patients with near-complete airway occlusion.
authors.affiliation: Department of Anesthesiology, University of California at San Francisco.
authors.forename: A
authors.initials: A
authors.lastname: Schapera
authors.forename: C R
authors.initials: CR
authors.lastname: Bainton
authors.forename: R
authors.initials: R
authors.lastname: Kraemer
authors.forename: K
authors.initials: K
authors.lastname: Lee
mesh_terms: D000402:Airway Obstruction / Q000628:therapy*; D000818:Animals; D004285:Dogs; D008168:Lung / Q000502:physiology; D008961:Models, Structural; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000295:instrumentation*