Recommendations for the measurement of FIV(1) values in chronic obstructive pulmonary disease

In contrast to static inspiratory parameters such as vital capacity and inspiratory capacity, information on forced inspiratory volume in 1 s (FIV(1)) in patients with chronic obstructive pulmonary disease (COPD) is limited.

It was the aim of this study to investigate the influence of the preceding expiratory manoeuvre and the optimal number of manoeuvres on FIV(1) values.

In 169 patients with COPD, FIV(1) manoeuvres were performed after a forced (FIV(1)-Fe) and a slow (FIV(1)-Se) expiration. To investigate the optimal number of the FIV(1)-Se manoeuvres, 8 attempts were performed.

The variability of FIV(1)-Fe was greater than that of FIV(1)-Se. The mean difference between FIV(1)-Se and FIV(1)-Fe was 0.21 litres (p < 0.01) and dependent on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage. The higher the GOLD stage, the greater the difference between the 2 techniques. The correlation coefficient between FIV(1)-Se and FIV(1)-Fe was high (r = 0.89, p = 0.01), but there was a poor agreement between these parameters (limits of agreement -0.52 to 0.94 litres). Five manoeuvres were needed to obtain an optimal FIV(1)-Se. There was no association with the GOLD stage.

In COPD patients, FIV(1)-Se are less variable than FIV(1)-Fe, the agreement between the 2 manoeuvres is poor, and at least 5 FIV(1)-Se manoeuvres are needed to get an acceptable FIV(1). This holds for all GOLD stages.