Apparatus for the Determination of Pulmonary Function Parameters
Original Publication Date: 2002-Jun-01
Included in the Prior Art Database: 2003-Jul-23
It is known that pulmonary function parameters such as shunt and diffusion resistance can be estimated both in normal subjects and in postoperative patients. This may be done by varying the inspired oxygen fraction in order to achieve oxygen saturations in the order of 0.90 to 1.00 and subsequently making mea- surements, such as flow, pressure, inspiratory and expiratory O 2 and CO 2 levels in the inspired and the expired breathing gases. SaO 2 measurements, for example using a pulse oxymeter, are also employed in the calculation of the pulmonary function para- meters. One reason for the lack of general use of such a calculation in patient monitoring is the ab- sence of a simple breathing apparatus adapted to facilitate the making of the above described measu- rements, used in the calculation of the above mentio- ned parameters. A breathing apparatus for the determination of pul- monary function parameters is shown in Fig. 1 and comprises a variable volume reservoir (2); a common flow conduit (4) connected at one end to the reser- voir (2) and connectable at the opposite end to a patient’s airways (not shown), for example via a face mask or an endotracheal tube; in gas communication with the conduit (4), a measuring head (6) for mea- suring inspiration and expiration gas parameters necessary for the calculation of the desired pulmona- ry function parameters and a CO 2 filter (8) to elimi- nate CO 2 from expiration gas after it has passed the measuring head (6); a calculations unit (10) to cal- culate and to optionally display the desired pulmona- ry function parameters from measurement values input from the measuring head (6) and from an opti- onal SaO 2 measurement device (12). A safety pressu- re release valve (14) may optionally be included in connection with the flow conduit (4).