PATTERN IDENTIFICATION OF OBSTRUCTIVE AND RESTRICTIVE VENTILATORY IMPAIRMENT THROUGH FLOW VOLUME CURVES

Abstract

Respiratory system performs functions of ventilation (V), perfusion (Q), and diffusion (DL). All respiratory function tests are based on the measurement of these functions. Spirometry measures the mechanical function of the lung, chest wall, and respiratory muscles by assessing the total volume of air exhaled from a full lung (total lung capacity [TLC]) to an empty lung (residual volume). This volume, the forced vital capacity (FVC) and the forced expiratory volume in the first second of the forceful exhalation (FEV1), should be reproducible to within 0.15 L upon repeat efforts unless the largest value for either parameter is less than 1 L. Flow-volume loop recording is one of the dynamic ventilatory function tests. This is a safe, simple and
reproducible. It is performed routinely in general practice. The shape of the flow-volume loop can differentiate between normal or abnormal lung function.