title: Prolonged partial liquid ventilation in spontaneously breathing awake animals.
abstract: OBJECTIVE
  To date, studies of partial liquid ventilation (PLV) have examined its effects acutely in anesthetized and mechanically ventilated subjects. We set out to develop a model of prolonged PLV in awake, spontaneously breathing animals.
  
  
  METHODS
  Animal case series
  
  
  METHODS
  Cardiopulmonary physiology laboratory.
  
  
  METHODS
  Fifteen New Zealand white rabbits (3.2+/-0.39 kg).
  
  
  METHODS
  Animals were anesthetized and instrumented with a novel technique allowing percutaneously assisted placement of an intratracheal catheter with a subcutaneously tunneled externalized free end. After anesthetic recovery, PLV was performed in spontaneously breathing unsedated animals.
  
  
  RESULTS
  Evaporative losses were determined using a single 10 mL/kg perflubron dose (n = 5); hourly radiographs were obtained until residual perflubron was minimal. For prolonged PLV (n = 10), a 10-mL/kg initial perflubron dose was followed every 4 hrs with 5-mL/kg supplements. Radiographs were obtained immediately before and after perflubron administration and were scored (0-5) by a radiologist blinded to dosing regimen and time interval. Data were analyzed with ANOVA and Student's t-test with correction for multiple comparisons. Initial filling was nearly complete (score = 4.8+/-0.42); lungs were maintained approximately half-filled through 4 hrs (score = 2.53+/-0.71). By 6 hrs, the majority of perflubron had evaporated (score = 1.75+/-0.53). Over 24 hrs, radiographs documented continuous perflubron exposure (postffill = 4.53+/-0.64, prefill = 3.40+/-0.71, average = 3.97+/-0.43); scores were comparatively higher after filling (after = 4.53+/-0.64, before = 3.4+/-0.71, p< .001). Left and right lung volumes were equivalent (left = 4.06+/-0.47, right = 3.89+/-0.39, p = .027). All animals survived the 24 hrs of PLV.
  
  
  CONCLUSIONS
  Percutaneously assisted intratracheal cannulation with catheter exteriorization permits prolonged PLV in spontaneously breathing, unsedated animals. Continuous perfluorocarbon exposure with this method is reproducible, consistent, and well tolerated for 24 hrs in uninjured animals.
authors.affiliation: Department of Surgery, The University of Michigan Hospitals, Ann Arbor, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Rich
authors.forename: C A
authors.initials: CA
authors.lastname: Reickert
authors.forename: S A
authors.initials: SA
authors.lastname: Mahler
authors.forename: S
authors.initials: S
authors.lastname: Sawada
authors.forename: S
authors.initials: S
authors.lastname: Awad
authors.forename: E A
authors.initials: EA
authors.lastname: Kazerooni
authors.forename: R B
authors.initials: RB
authors.lastname: Hirschl
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D005466:Fluorocarbons / Q000627:therapeutic use*; D006842:Hydrocarbons, Brominated; D007322:Instillation, Drug; D007442:Intubation, Intratracheal / Q000379:methods*; D008176:Lung Volume Measurements; D011817:Rabbits; D012119:Respiration; D012121:Respiration, Artificial / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D016037:Single-Blind Method; D013997:Time Factors; D014139:Tracheostomy; D014851:Wakefulness
chemical_list: D005466:Fluorocarbons; D006842:Hydrocarbons, Brominated; C003072:perflubron