title: Experimental study of double-lumen, two-stage endotracheal tube during conventional mechanical ventilation in rabbits.
abstract: OBJECTIVE
  To evaluate the effects of a double-lumen, two-stage endotracheal tube on gas exchanges (ventilatory efficiency) during conventional mechanical ventilation, using a ventilator in rabbits.
  
  
  METHODS
  Prospective, randomized, crossover laboratory animal trial.
  
  
  METHODS
  Research laboratory in the Beijing Children's Hospital.
  
  
  METHODS
  Five adult New Zealand rabbits, weighing 3.2 to 3.7 kg.
  
  
  METHODS
  A new type of endotracheal tube-the double-lumen two-stage endotracheal tube-was designed and tested for ventilation efficiency in rabbits with normal and injured lungs. The new tube (size 3.0 mm) was made out of two Portex endotracheal tubes (size 3.0 mm) by adhering two vertical cross-sections at the distal end of the two tubes. The new tube and a conventional endotracheal tube of the same size (inner diameter 3.0 mm) were randomly used in pressure control ventilation. Each trial was maintained for 30 mins.
  
  
  RESULTS
  Effects from the two endotracheal tubes on pulmonary mechanics, hemodynamics, and gas exchange were observed. We measured peak inspiratory pressure, positive end-expiratory pressure (PEEP), intrinsic PEEP, mean airway pressure, and arterial blood and mixed expired gas variables (Pao2, Paco2, pH, and mixed expired gas Pco2). The new endotracheal tube acutely increased CO2 elimination in all animals with normal and injured lungs. Paco2 decreased from 46 +/- 4 to 36 +/- 5 torr (6.1 +/- 0.5 to 4.8 +/- 0.7 kPa; p < .01) in normal lungs and from 48 +/- 5 to 36 +/- 5 (6.4 +/- 0.7 to 4.8 +/- 0.7 kPa; p < .01). Meanwhile, tidal volume fraction decreased from 0.48 +/- 0.07 to 0.35 +/- 0.05 (p < .01) and from 0.56 +/- 0.07 to 0.40 +/- 0.07 (p < .01) in normal and injured lungs, respectively. Intrinsic PEEP of the new tube slightly increased, but there were no significant differences in comparison with the conventional tube.
  
  
  CONCLUSIONS
  Compared with the conventional endotracheal tube, the new double-lumen, two-stage endotracheal tube reduced Paco2 by decreasing anatomical deadspace in rabbits with normal and injured lungs under pressure control ventilation, thus enhancing ventilatory efficiency and reducing ventilator-induced injury.
authors.affiliation: Pediatric Intensive Care Unit, Beijing Children's Hospital, PR, China.
authors.forename: X N
authors.initials: XN
authors.lastname: Chen
authors.forename: J C
authors.initials: JC
authors.lastname: Wu
authors.forename: R
authors.initials: R
authors.lastname: Geng
authors.forename: X P
authors.initials: XP
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001784:Blood Gas Analysis; D018592:Cross-Over Studies; D004195:Disease Models, Animal; D004867:Equipment Design; D006439:Hemodynamics; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D011659:Pulmonary Gas Exchange; D011817:Rabbits; D011897:Random Allocation; D012121:Respiration, Artificial / Q000295:instrumentation*; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*; D015656:Respiratory Mechanics