title: The influence of xenon, nitrous oxide and nitrogen on gas bubble expansion during cardiopulmonary bypass.
abstract: OBJECTIVE
  Xenon may have favourable applications in the setting of cardiac surgery. Its advantages include a desirable haemodynamic profile as well as potential cardiac and neuroprotective properties. However, its low solubility may lead to enhanced diffusion into enclosed gas spaces. The purpose of this study was to compare the effects of xenon (Xe), nitrous oxide (N2O) and nitrogen (N2) on gas bubble size during cardiopulmonary bypass (CPB).
  
  
  METHODS
  Rats were randomized to receive 70% Xe, 26% oxygen (O2), 4% carbon dioxide (CO2) (xenon group); 70% N2O, 26% O2, 4% CO2 (nitrous oxide group) or 70% N2, 26% O2, 4% CO2 (nitrogen group) during 90 min of normothermic CPB. Small gas bubbles (300-500 microL; n = 12 per group) were injected into a bubble chamber on the venous side of the bypass circuit. After 10 min of equilibration, they were removed for volumetric analysis.
  
  
  RESULTS
  The increase in bubble size was 2 +/- 2% with nitrogen, 17 +/- 6% with xenon (P = 0.0192 vs. nitrogen) and 63 +/- 23% with nitrous oxide (P = 0.0001 vs. nitrogen). The nitrous oxide group had significantly increased bubble size compared to the xenon group (P = 0.0001).
  
  
  CONCLUSIONS
  During CPB, xenon anaesthesia produced a small increase in gas bubble size compared to nitrogen. Nitrous oxide resulted in significantly larger bubbles compared to both nitrogen and xenon.
authors.affiliation: Duke University Medical Center, Division of Cardiothoracic Anesthesiology and Critical Care Medicine, Department of Anesthesiology, Durham, NC 27710, USA. h.grocott@duke.edu
authors.forename: H P
authors.initials: HP
authors.lastname: Grocott
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: H M
authors.initials: HM
authors.lastname: Homi
authors.forename: B E
authors.initials: BE
authors.lastname: Smith
mesh_terms: D000704:Analysis of Variance; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D001784:Blood Gas Analysis / Q000379:methods; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D002315:Cardiopulmonary Bypass / Q000379:methods*; D004058:Diffusion / Q000187:drug effects; D005740:Gases; D006454:Hemoglobins / Q000187:drug effects; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008297:Male; D045423:Microbubbles; D009584:Nitrogen / Q000494:pharmacology*; D009609:Nitrous Oxide / Q000494:pharmacology*; D010316:Particle Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D014978:Xenon / Q000494:pharmacology*
chemical_list: D018685:Anesthetics, Inhalation; D005740:Gases; D006454:Hemoglobins; D014978:Xenon; D009609:Nitrous Oxide; D009584:Nitrogen