ATS Pulmonary Function Laboratory Manual

ATS Pulmonary Function Laboratory Management & Procedure Manual | 3rd Edition

Figure 9.4  “Too slow.” Graphic representation of open-shutter loops with a patient panting too slowly. Generally, this pattern occurs when the panting rate is less than 1.5 cycles/s. This is easily corrected by having the patient increase the panting speed without changing the volume per pant. However, a similar pattern is commonly en- countered with patients having large amounts of trapped gas which, despite increasing the pant frequency, will not result in loop closure.

Figure 9.5  “Too fast.” Graphic representation of the patient panting too rapidly and either exceeding the frequency response characteris- tics of their plethysmograph or inhomogeneity of time constants be- tween lung units. This situation is commonly remedied by instruct- ing the patient to slow down panting frequency. Use of a metronome or similar device helps the technologist develop the optimal panting frequency.

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