title: Gas exchange and lung mechanics during percutaneous transtracheal ventilation in an unparalyzed canine model.
abstract: OBJECTIVE
  To compare the efficacy of percutaneous transtracheal ventilation (PTV) in the unparalyzed state with that in the paralyzed state using a sedated nonobstructed canine model.
  
  
  METHODS
  Eight mongrel dogs (16.8-32 kg) were anesthetized, instrumented, and placed in a volume plethysmograph. Anesthesia was achieved with pentobarbital sodium (up to 30 mg/kg). The spontaneous respiratory drive was kept intact. PTV was performed using a 13-ga transtracheal catheter and compressed air at 45 psi at an I:E ratio of 1:3 (15 breaths/min). Each dog was sequentially ventilated in both the paralyzed and unparalyzed states. The paralyzed/unparalyzed sequence was alternated among the animals to avoid sequence bias. Paralysis was achieved with succinylcholine (0.1 mg/kg bolus and 0.01 mg/kg/min drip). Reversal of paralysis was achieved by discontinuing the succinylcholine infusion. Key variables, including arterial blood gas, tidal volume, and pulmonary mechanics, were measured and compared for the paralyzed and unparalyzed states.
  
  
  RESULTS
  Gas exchanges and lung mechanics were similar between the unparalyzed and paralyzed states. There was no significant difference in mean pH, pCO2, pO2, tidal volume, or peak inspiratory transpulmonary pressure. There was also no significant difference in pulmonary resistance or pulmonary compliance.
  
  
  CONCLUSIONS
  In a sedated nonobstructed canine model, PTV is as efficacious in the unparalyzed state as it is in the paralyzed state. The lung mechanics are also similar in the 2 states. These data suggest that it may be unnecessary to induce paralysis when using PTV for emergency ventilation in the heavily sedated state.
authors.affiliation: Department of Surgery, University of Nebraska Medical Center, Omaha 68198-1150, USA. ttran@unmc.edu
authors.forename: T P
authors.initials: TP
authors.lastname: Tran
authors.forename: K J
authors.initials: KJ
authors.lastname: Rhee
authors.forename: H D
authors.initials: HD
authors.lastname: Schultz
authors.forename: M L
authors.initials: ML
authors.lastname: Carl
mesh_terms: D000818:Animals; D018592:Cross-Over Studies; D004285:Dogs; D008168:Lung / Q000502:physiology*; D010243:Paralysis / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics; D014132:Trachea