How can I measure my capacity for inspiration

Lung volumes, lung capacities, Tiffeneau test

 
Print preview

Printing and copying of the page is only possible for registered users!

Course:Patient observation - breathing (part 2): breathing disorders, diagnostic measures

Lesson:1

Page title:Lung volumes, lung capacities, Tiffeneau test


There are more volumes in the lungs than normal inhalation and exhalation.

The different lung volumes are determined during the lung function test. In the case of certain diseases that lead to breathing disorders, these volumes change.

Important note: There are significant fluctuations in terms of lung volumes. In women, for example, the lung volumes are generally ten to 20% smaller. There are also age-related changes. Last but not least, lifestyle has an impact, for example, certain lung volumes are increased in athletes. The numbers below refer to a young, healthy male adult.

Please take a look at the following picture. Further down on the page, I'll go into the individual volumes and their disease-related changes.



Fig. 6: Diagnosis of dyspnea - lung volumes, © Andreas Heimann-Heinevetter


Tidal volume (AZV)



Fig. 7: Diagnostics for dyspnea - tidal volume AZV, © Andreas Heimann-Heinevetter

The tidal volume is the volume of one breath. Normally it is around 500 ml in adults. The tidal volume is reduced, e.g. if the respiratory muscles are weak. It is physiologically increased during physical exertion. The tidal volume is also known as the tidal volume. The usual abbreviation in German-speaking countries is AZV.

While a decrease in the tidal volume (shallow breathing) is actually always a sign of illness, an increase in the tidal volume can have disease-independent reasons.


Inspiratory Reserve Volume (IRV)



Fig. 8: Diagnostics for dyspnea - inspiratory reserve volume IRV, © Andreas Heimann-Heinevetter

The inspiratory reserve volume is the volume that can be additionally inhaled after normal inhalation. The inspiratory reserve volume is normally around 3.0 liters. The inspiratory reserve volume is abbreviated as IRV.


Expiratory reserve volume (ERV)



Fig. 9: Diagnosis of dyspnea - expiratory reserve volume IRV, © Andreas Heimann-Heinevetter

The expiratory reserve volume is the tidal volume that you can also exhale after normal exhalation. Usually it is around 1.2 liters. The expiratory reserve volume is abbreviated as ERV.


Residual volume (RV)



Fig. 10: Diagnostics for dyspnea - residual volume RV, © Andreas Heimann-Heinevetter

The residual volume is the volume that remains in the lungs after maximum exhalation. It is about 1.3 liters. The residual volume is abbreviated as RV. The residual volume can only be measured with a complex test procedure.

If one summarizes the individual lung volumes, one obtains the lung capacities.


Inspiratory Capacity (IC)



Fig. 11: Diagnosis of dyspnea - inspiratory capacity IK, © Andreas Heimann-Heinevetter

If you add the normal tidal volume and the inspiratory reserve volume, you get the inspiratory capacity. In other words, the maximum volume that can be inhaled after normal exhalation.

AZV + IRV = IK

The inspiration capacity is usually around 3.5 liters.


Functional residual capacity (FRK or FRC)



Fig. 12: Diagnostics for dyspnea - functional residual capacity FRC, © Andreas Heimann-Heinevetter

If you add the residual volume and the expiratory reserve volume, you get the functional residual capacity, i.e. the volume that remains in the lungs after normal exhalation.

RV + ERV = FRC

Typically the functional residual capacity is 2.5 liters.


Vital capacity (VC)


Fig. 13: Diagnostics for dyspnea - vital capacity VC, © Andreas Heimann-Heinevetter

Well, I think you already have an idea of ​​what is meant by vital capacity. The volume of the lungs that you can move with maximum exhalation and inhalation. So you add the expiratory reserve volume with the normal tidal volume and the inspiratory reserve volume.


ERV + AZV + IRV = VC


Normally the vital capacity is 4.7 liters.

The vital capacity can be determined in four variations. This distinction is important. In the case of healthy lungs, all values ​​determined are approximately the same, in contrast to those with lung disease.


  • Inspiratory Vital Capacity (IVC)

    Inspirational vital capacity is the volume that can be inhaled all at once after maximum exhalation.

  • Expiratory Vital Capacity (EVC)

    Expiratory vital capacity is the volume that can be exhaled all at once after maximum inhalation.

  • Forced inspiratory vital capacity (FIVC)

    Forced inspiratory vital capacity is the volume that can be forcefully inhaled all at once after maximum exhalation.

  • Forced expiratory vital capacity (FVC)

    Forced expiratory vital capacity is the volume that can be forced out all at once after maximum inhalation.

In patients with obstructive pulmonary disease (e.g. bronchial asthma, COLD), however, the values ​​change in a characteristic way.

IVC> EVC> FVC

The inspiratory vital capacity is greater than the expiratory vital capacity and this in turn is greater than the forced expiratory vital capacity.


Total capacity (TC or TLC)



Fig. 14: Diagnostics for dyspnea - total capacity VC, © Andreas Heimann-Heinevetter

The total volume of air that is in the lungs after maximum inhalation is referred to as total capacity. It is usually around six liters.


Dead space


When breathing, not the entire volume in the airways takes part in the gas exchange, but only the volume that is in the alveoli.

The air in the bronchi, trachea, larynx, throat and nose (oral cavity) is excluded from gas exchange. This air or these spaces are referred to as "dead space". Nevertheless, the dead space is important;

The total volume is approx. 150 ml. This means that with a breath of 500 ml, only 350 ml take part in the gas exchange. If the breathing is very shallow, e.g. only 300 ml per breath, only 150 ml take part in the gas exchange.


Tiffeneau Test, Forced Expiratory Volume / Second (One Second Capacity - FEV1)


In the Tiffeneau test (breath test), the vital capacity is determined first. The patient is then asked to inhale as much as possible and then exhale as forcefully as possible. The volume of air that could be exhaled in one second is measured. This exhalation volume is called the one-second capacity.

The one-second capacity is usually between 75 and 85% of the vital capacity.

This information on the Tiffeneau test is based on printed sources. If you do a little research, you will find different information about the Tiffeneau test. I opted for the definition described above because printed sources are mostly proofread by an editor (my courses too, by the way).

In obstructive lung diseases, the one-second capacity decreases in relation to the vital capacity, i.e. the percentage value becomes smaller. The cause is the increased flow resistance due to the narrowed airways.


Restrictive ventilation disorders


In the case of restrictive ventilation disorders, the extensibility of the lungs (compliance) is pathologically restricted. This is the case, for example, with pulmonary fibrosis or adhesions on the pleural membranes, but also with deformities of the chest. The lungs and chest cannot expand enough.

With restrictive ventilation disorders, the vital capacity and the residual volume of the lungs decrease. The one-second capacity usually remains the same.


Obstructive ventilation disorders


In the case of obstructive ventilation disorders, the airway resistance is increased, e.g. due to foreign bodies, secretions, edema, bronchial asthma, COLD or pulmonary emphysema.

In the case of obstructive ventilation disorders, the residual volume increases, the one-second capacity (FEV1) decreases, and the forced expiratory vital capacity (FVC) remains the same. In the later course there is a decrease in vital capacity.



A printout of the page is only possible for registered users!