title: Correlation between pulmonary gas exchange and basal and nitroglycerin (GTN)-induced exhaled nitric oxide (eNO) in patients undergoing cardiac surgery.
abstract: The relationship between eNO and events in the alveolar-capillary unit in acute lung injury remains to be established. Since endogenous eNO largely originates from the airway epithelium, but nitroglycerin (GTN)-induced eNO is due to microvascular/alveolar metabolism, we have proposed to use basal and GTN-induced eNO as metabolic markers of the airway--and microvascular/alveolar function, respectively. The current work investigates the relationship between basal and GTN-induced eNO and oxygenation parameters (PaO(2)/FiO(2) ratio) in patients undergoing cardiac surgery utilising cardiopulmonary bypass (CPB). Breath by breath eNO measurements were made in 10 patients before, and 1 and 3 h after CPB either under basal conditions or following intravenous administration of GTN (1, 2 and 3 microg/kg). Basal eNO remained unchanged, whereas GTN-induced eNO was reduced following CPB. Also, there was a transient reduction in PaO(2)/FiO(2) ratio 1 h after CPB (32+/-4 vs. 44+/-3 kPa). A negative correlation was found between oxygenation and basal eNO by Pearson's correlation test and linear regression analysis suggesting that decreased oxygenation was associated with increased basal eNO. In contrast, a decrease in GTN-induced eNO positively correlated with reduced oxygenation index (R=0.533, p=0.002). These data suggest that differential relationships exist between basal and nitrovasodilator-induced eNO and oxygenation indices during subclinical lung injury in patients following CPB and that GTN-induced eNO evolution may reflect better microvascular events and injury.
authors.affiliation: Department of Anaesthetics, Royal Brompton and Harefield NHS Trust, Heart Science Centre, Harefield Hospital, Harefield, UK.
authors.forename: Tamás
authors.initials: T
authors.lastname: Kövesi
authors.forename: Anita
authors.initials: A
authors.lastname: Szabo
authors.forename: David
authors.initials: D
authors.lastname: Royston
authors.forename: Nándor
authors.initials: N
authors.lastname: Marczin
mesh_terms: D001944:Breath Tests; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007275:Injections, Intravenous; D009569:Nitric Oxide / Q000378:metabolism*; D005996:Nitroglycerin / Q000008:administration & dosage / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange; D012044:Regression Analysis; D012121:Respiration, Artificial; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D009569:Nitric Oxide; D005996:Nitroglycerin