title: Small-dose nitric oxide improves oxygenation during one-lung ventilation: an experimental study.
abstract: Inhaled nitric oxide (NO) at 20 or 40 ppm does not improve arterial oxygenation during one-lung ventilation (OLV). The authors hypothesized that NO at smaller concentrations might improve oxygenation. Twelve piglets weighing 26 to 32 kg were studied. When PaO(2) had reached a plateau during OLV, NO at doses of 4, 8, 16, and 32 ppm were randomly administered for 30 min. Hemodynamic data were determined by invasive monitoring. Blood gas analysis and, in six animals, ventilation-perfusion analysis by the multiple inert gas elimination technique were used to characterize pulmonary gas exchange. NO at 4, 8, 16, and 32 ppm improved PaO(2) during OLV. NO at 4 ppm had a more intense effect on arterial oxygenation than doses of 8, 16, and 32 ppm (DeltaPaO(2), 42 +/- 35 mm Hg versus 22 +/- 20 mm Hg, 13 +/- 18 mm Hg, and 15 +/- 16 mm Hg; P < 0.05). NO at 4 ppm reduced intrapulmonary shunt flow, whereas a larger concentration exhibited no statistically significant effect. The authors conclude that NO improves arterial oxygenation more effectively at smaller doses than at larger doses. This dose-dependent effect remains to be confirmed in acute hypoxemia during OLV.
  
  
  CONCLUSIONS
  Inhaled nitric oxide at 4 ppm improves arterial oxygenation during one-lung ventilation to a greater extent than larger doses, and this effect is caused by a reduction in intrapulmonary shunt.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, Justus-Liebig University, Giessen, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Sticher
authors.forename: Stefan
authors.initials: S
authors.lastname: Scholz
authors.forename: Olav
authors.initials: O
authors.lastname: Böning
authors.forename: Ralph Theo
authors.initials: RT
authors.lastname: Schermuly
authors.forename: Claudia
authors.initials: C
authors.lastname: Schumacher
authors.forename: Dieter
authors.initials: D
authors.lastname: Walmrath
authors.forename: Gunter
authors.initials: G
authors.lastname: Hempelmann
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D009569:Nitric Oxide / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism*; D012121:Respiration, Artificial / Q000379:methods*; D013552:Swine; D014692:Ventilation-Perfusion Ratio / Q000187:drug effects
chemical_list: D009569:Nitric Oxide; D010100:Oxygen