Document Detail

The mechanism of nitrous oxide-induced changes in pulmonary vascular resistance in a dog model of left atrial outflow obstruction.
MedLine Citation:
PMID:  2520935     Owner:  NLM     Status:  MEDLINE    
Nitrous oxide has been reported to increase pulmonary vascular resistance (PVR) in patients with pulmonary hypertension secondary to mitral stenosis. Additional data suggest this response involves sympathetic stimulation because the increase in PVR can be prevented by alpha-adrenergic and ganglionic blockade. Whether or not active pulmonary vasoconstriction occurs remains unclear. This study was designed to more fully characterize the influence of N2O on pulmonary hemodynamics during left atrial outflow obstruction (LAO). Responses in an in situ blood-perfused lung lobe were compared with those in the remaining intact lung of six dogs anesthetized with pentobarbital, 30 mg/kg, and morphine, 1.5 mg/kg, and prepared for measurement of peak left ventricular (LV) pressure, LV end-diastolic pressure (LVEDP), LV dP/dt, systemic arterial and pulmonary arterial (PA) pressures, and cardiac output (CO). The pulmonary artery branch supplying the left middle lung lobe was cannulated and perfused at a constant rate with warmed blood. LAO was produced by filling the balloon of a Foley catheter positioned in the left atrium (LA) with enough saline to increase PA pressure by 50%; the balloon was subsequently left filled for the entire protocol. Measurements were first obtained during ventilation with 67% N2, and 33% O2. The inspired gas was then changed to 67% N2O and 33% O2 for 10 minutes, and then returned to the N2/O2 mixture. Once baselines had been reestablished (about 10 minutes), phentolamine, 0.75 mg/kg, was administered, and the response to 10 minutes of N2O again observed. N2O did not change vascular resistance in the isolated lobe, but increased intact-lung PVR.(ABSTRACT TRUNCATED AT 250 WORDS)
P M Heerdt; R W Caldwell
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of cardiothoracic anesthesia     Volume:  3     ISSN:  0888-6296     ISO Abbreviation:  J Cardiothorac Anesth     Publication Date:  1989 Oct 
Date Detail:
Created Date:  1992-08-18     Completed Date:  1992-08-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8709732     Medline TA:  J Cardiothorac Anesth     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  568-73     Citation Subset:  IM    
Department of Pharmacology, University of Tennessee, Memphis.
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MeSH Terms
Anesthesia, Inhalation*
Atrial Function, Left / drug effects
Blood Pressure / drug effects
Cardiac Output / drug effects
Lung / blood supply*
Nitrous Oxide / pharmacology*
Phentolamine / pharmacology
Pulmonary Artery / physiopathology
Pulmonary Circulation / drug effects
Stroke Volume / drug effects
Vascular Resistance / drug effects*
Ventricular Function, Left / drug effects
Ventricular Outflow Obstruction / physiopathology*
Grant Support
Reg. No./Substance:
10024-97-2/Nitrous Oxide; 50-60-2/Phentolamine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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