ATS Pulmonary Function Laboratory Manual

chapter  9

Appendix 9.2  Examples of Open- and Closed-Shutter Loops for Raw Measurements

Figure 9.1  Open-shutter loop. Graphic representation of an open- shutter Raw loop whereby Δ Box Pressure are plotted against Δ Flow.

Figure 9.2  Closed-shutter loop. Depiction of tracing derived when the mouth shutter closes and the patient pants against it, alternately compressing and decompressing the thoracic gas, with resultant Δ Mouth Pressure plotted against Δ Box Pressure.

Figure 9.3  Open- and closed-shutter loops. Representation of the combined loops (superimposed) as commonly depicted with com- mercially available Raw measurement software. Absolute configura- tions are dependent upon the specific manufacturer.

97