title: Xenon inhalation increases airway pressure in ventilated patients.
abstract: BACKGROUND
  The inert gas xenon, known as an anaesthetic for nearly 50 years, is also used as a contrast agent during computerised tomography (CT)-scanning. As xenon has a higher density and viscosity than air, xenon inhalation may increase airway resistance.
  
  
  METHODS
  In a retrospective study we investigated the effects of 33% xenon/67% oxygen on airway pressure and cardio-respiratory parameters in 37 long-term mechanically ventilated patients undergoing cerebral blood flow (rCBF) measurements by means of stable xenon-enhanced CT.
  
  
  RESULTS
  Xenon administration caused a significant increase in peak airway pressure from 31.6+/-8.0 cm H2O to 42.7+/-16.9 cm H2O. This effect was reproducible, did not occur after reduction of inspiratory flow rate by 50% from 0.56+/-0.15 L x s(-1) to 0.28+/-0.08 L x s(-1), and vanished immediately after termination of xenon delivery.
  
  
  CONCLUSIONS
  Due to the higher density and viscosity of this gas mixture, ventilation with xenon/oxygen produces a higher Reynolds' number than oxygen/air when given at the same flow rate. This means that during xenon ventilation the zone of transition from turbulent to laminar gas flow may be located more peripherally (in smaller airways) than during oxygen/air ventilation with a subsequent increase in airway resistance. Our results indicate that xenon inhalation may cause a clinically relevant increase of peak airway pressure in mechanically ventilated patients.
authors.affiliation: Dept. of Anaesthesiology, Hannover Medical School, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Rueckoldt
authors.forename: B
authors.initials: B
authors.lastname: Vangerow
authors.forename: G
authors.initials: G
authors.lastname: Marx
authors.forename: B
authors.initials: B
authors.lastname: Haubitz
authors.forename: M C
authors.initials: MC
authors.lastname: Meyer
authors.forename: S
authors.initials: S
authors.lastname: Piepenbrock
authors.forename: M
authors.initials: M
authors.lastname: Leuwer
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000403:Airway Resistance / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D012121:Respiration, Artificial; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014978:Xenon / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D002245:Carbon Dioxide; D014978:Xenon; D010100:Oxygen