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Variable
effort can be detected by a flow volume loop that fails to demonstrate the normal early
peak, showing that the patient failed to expire maximally when instructed to do so. Early
glottic closure is seen as an abrupt cessation of flow during expiration, visible as a
sharp downslope on the expiratory flow volume curve. Coughing during spirometry appears as
sharp spikes in the decreasing limb of the flow volume curve. The quality of a spirogram can be assessed, by examining the flow
volume loops. In addition, the technician working with the patient should comment on the
patient's effort and the session as a whole. At least 3 efforts must be attempted to meet
reproducibility criteria. |
