Vital Capacity

Hello, I work for an OH provider and I write the respiratory directory, what I would like to ask if there is any reason for carrying out VC ? as we only document the FVC FVC1 FEV1/FVC I do not feel that we need to carry out VC as we are not documenting this and we are not diagnosing, please can you point me in the right direction for seeing if there is any research into this Many Thanks Fiona Gove RI, Shepherd J, Burge PS, Variability and reversibility of the slow and forced vital capacity in chronic airflow obstruction., Br J Dis Chest, 1987;81:182-185,

Occupational Asthma, Health Professional, 1/3/2020, 1/9/2020,

Hi Fiona, Thanks for your question. The VC is a useful measure for those with obstruction to see if there is a difference between the VC and the FVC. This could probably just be performed at baseline initially (on all) and then FEV1/FVC followed from then on. If the spirometry starts to become obstructive, a repeat of VC would be warranted. The difference between VC and FVC can give an indication of air trapping which can be useful in the diagnosis of lung disease. Many thanks Vicky

1/8/2020

You are likely to get different replies from physiologists and clinicians, particularly those testing healthy working populations. Speaking as a clinician I think the differences in forced and slow VCs are really only of relevance in those with fairly severe airflow obstruction, particularly those who have pressure-dependant collapse of their airways such as can occur with emphysema. If you do not stop forced expiration until the flow plateaus the differences in VC and FVC are very small, even in those with severe airflow obstruction, the problem is that expiration needs to be very long, often over 20 seconds, when you are doing a Val Salva manoeuvre and you worker might faint. The current spirometry guidelines recommend stopping at 16 seconds, in this case the VC may be grater than the FVC. In practice few report serial VC or FVC changes in occupational cohorts, as the quality of FVC measurements is often suboptimal. FVC decline is a standard outcome measure in those with restrictive lung disease, when the FEV1 and FVC are usually very close and the forced expiratory time <3 seconds. Using Spirola to calculate FEV1 decline in my opinion should be the priority in occupational cohorts. Hnizdo E, Glindmeyer HW, Petsonk EL., Workplace spirometry monitoring for respiratory disease prevention: a methods review., Int J Tuberc Lung Dis, 2010;14:796-805, Hnizdo E, Yu L, Freyder L, Attfield M, Lefante J, Glindmeyer HW, The precision of longitudinal lung function measurements: monitoring and interpretation, Occup Environ Med, 2005;62:695-701,

1/9/2020

You are likely to get different replies from physiologists and clinicians, particularly those testing healthy working populations. Speaking as a clinician I think the differences in forced and slow VCs are really only of relevance in those with fairly severe airflow obstruction, particularly those who have pressure-dependant collapse of their airways such as can occur with emphysema. If you do not stop forced expiration until the flow plateaus the differences in VC and FVC are very small, even in those with severe airflow obstruction, the problem is that expiration needs to be very long, often over 20 seconds, when you are doing a Val Salva manoeuvre and you worker might faint. The current spirometry guidelines recommend stopping at 16 seconds, in this case the VC may be grater than the FVC. In practice few report serial VC or FVC changes in occupational cohorts, as the quality of FVC measurements is often suboptimal. FVC decline is a standard outcome measure in those with restrictive lung disease, when the FEV1 and FVC are usually very close and the forced expiratory time <3 seconds. Using Spirola to calculate FEV1 decline in my opinion should be the priority in occupational cohorts. Gove RI, Shepherd J, Burge PS, Variability and reversibility of the slow and forced vital capacity in chronic airflow obstruction., Br J Dis Chest, 1987;81:182-185,

1/9/2020