Method for determining the functional residual capacity of lungs and a ventilator for practicing said method

US5540233A · kind A · utility

Assignee

• Siemens Elema AB · SE

Inventors

• Anders Larsson · Lotorp, SE
• Rolf Castor · Stuvsta-Snättringe, SE
• Stefan Brauer · Waiblingen, DE
• Sven-Gunnar Olsson · Ždírec nad Doubravou, CZ

Key dates

• Filing date: Oct 24, 1994
• Grant date: Jul 30, 1996
• Expiry date: Oct 24, 2014

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61B5/0813
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

In a method and a ventilator device for measuring the functional residual capacity, FRC, of lungs, a trace gas is mixed with a breathing gas in a gas mixer and the mixture os fed into the lungs via an inspiratory tube. When a predetermined concentration of trace gas is achieved in the lungs, the supply of trace gas is stopped, and a washout phase starts. During the washout phase, the concentration of trace gas in expired gas and the flow of expired gas are measured. The measurement values are sent to an analyzer which calculates the volume of trace gas in the lungs. Functional residual capacity can then be determined from the calculated volume of trace gas. The trace gas is preferably SF.sub.6.