title: Macroscopic barotrauma caused by stiff and soft-tipped airway exchange catheters: an in vitro case series.
abstract: BACKGROUND
  Many airway management guidelines include the use of airway exchange catheters (AECs). There are reports, however, of harm from their use, from both malpositioning and in particular from the administration of oxygen via an AEC leading to barotrauma.
  
  
  METHODS
  We used an in vitro pig lung model to investigate the safety of administering oxygen at 4 different flow rates from a high-pressure source via 2 different AECs: a standard catheter and a soft-tipped catheter. Experiments were performed with the catheters positioned either above the carina or below it at the first point of resistance to advancement (hold-up). The experiments were then repeated to produce a series of 32 cases.
  
  
  RESULTS
  With an AEC positioned above the carina, we did not observe macroscopic lung damage after the administration of oxygen. The administration of oxygen through an AEC positioned below the carina resulted in macroscopic barotrauma regardless of the rate of oxygen delivery. Increasing speed of oxygen flow led to faster and more extensive damage. Use of an "injector" at 2.5 or 4 bar led to instantaneous macroscopic lung damage and advancement of the AEC through the lung tissue. Our observations were the same when both types of AECs were used.
  
  
  CONCLUSIONS
  Our results are consistent with reports of harm during the use of AECs and demonstrate the risk of administering oxygen through these devices when they are positioned below the carina. An indicator, ideally made on an AEC at the time of manufacture and designed to lie at the same level as the teeth, may be useful in preventing the insertion of that AEC beyond the level of the carina and improve the safety of using such devices.
authors.affiliation: From the *Department of Anaesthesia and Intensive Care Medicine, Royal United Hospital Bath, Bath, United Kingdom; and †Department of Thoracic Surgery, Bristol Royal Infirmary, Bristol, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Axe
authors.forename: Alex
authors.initials: A
authors.lastname: Middleditch
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Kelly
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Batchelor
authors.forename: Tim M
authors.initials: TM
authors.lastname: Cook
mesh_terms: D058109:Airway Management / Q000009:adverse effects* / Q000295:instrumentation*; D000818:Animals; D001469:Barotrauma / Q000209:etiology* / Q000473:pathology; D057785:Catheters / Q000009:adverse effects*; D066298:In Vitro Techniques; D008168:Lung / Q000473:pathology; D010100:Oxygen / Q000008:administration & dosage; D012121:Respiration, Artificial / Q000009:adverse effects; D013552:Swine; D014132:Trachea / Q000293:injuries / Q000473:pathology
chemical_list: D010100:Oxygen