Biomaterial Database

Failure of the Kety-Schmidt nitrous oxide method for determination of myocardial blood flow. 1991

M A Reid, and L E Mather, and W B Runciman, and C F McLean

Department of Anaesthesia and Intensive Care, Flinders Medical Centre, Flinders University of South Australia, Adelaide.

1. The reliability of the Kety-Schmidt nitrous oxide (N2O) blood-tissue equilibration method was examined in 50 studies of myocardial blood flow in seven conscious, unrestrained sheep using a newly developed carefully validated gas chromatographic assay for N2O. 2. In 10 studies the arterial and coronary sinus N2O blood concentration-time curves converged as expected at the end of the 10 min sampling period. In 14 studies they crossed over, and in 26 studies, the curves failed to converge. 3. A survey of the literature revealed that such results have been encountered previously but have not been accorded particular significance. An ultimate matching equilibrium between arterial and venous blood N2O concentration-time curves is, however, fundamental to the validity of the method. 4. The results indicate that the use of the Kety-Schmidt method with N2O as the indicator gas is invalid as applied to the measurement of myocardial blood flow in this preparation.

UI	MeSH Term	Description	Entries
D009609	Nitrous Oxide	Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream.	Laughing Gas,Nitrogen Protoxide,Gas, Laughing,Oxide, Nitrous
D001794	Blood Pressure	PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.	Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
D002404	Catheterization	Use or insertion of a tubular device into a duct, blood vessel, hollow organ, or body cavity for injecting or withdrawing fluids for diagnostic or therapeutic purposes. It differs from INTUBATION in that the tube here is used to restore or maintain patency in obstructions.	Cannulation,Cannulations,Catheterizations
D002849	Chromatography, Gas	Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.	Chromatography, Gas-Liquid,Gas Chromatography,Chromatographies, Gas,Chromatographies, Gas-Liquid,Chromatography, Gas Liquid,Gas Chromatographies,Gas-Liquid Chromatographies,Gas-Liquid Chromatography
D003326	Coronary Circulation	The circulation of blood through the CORONARY VESSELS of the HEART.	Circulation, Coronary
D005260	Female		Females
D006339	Heart Rate	The number of times the HEART VENTRICLES contract per unit of time, usually per minute.	Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012756	Sheep	Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.	Ovis,Sheep, Dall,Dall Sheep,Ovis dalli