Spiroergometry

The Spiroergometry is a diagnostic method for measuring cardiopulmonary performance. For this purpose, the so-called breathing gases, oxygen and carbon dioxide, are measured during a defined physical activity. The procedure is particularly important in pulmonary medicine and for monitoring therapy and progress.

What is spiroergometry?

Spirometry is a compound term from the two words spirometry and ergometry. The Latin word Spiro means breathing, Ergo comes from the Greek and means measure of work.

During spiroergometry, the patient is subject to constant stress, for example on a treadmill, while breathing is controlled with a mask specially developed for this purpose. In addition, an electrocardiogram can also be derived. Overall, the spiroergometry allows conclusions to be drawn about the performance and the reaction of metabolism, breathing, heart and circulation under stress.

The doctor determines the level of exposure because the patient should not be endangered by excessive exposure during the maneuver. During a spiroergometry, which is also called Ergospirography or Ergospirometry is known, certain parameters, i.e. measured values, are continuously collected, which are of great importance for the diagnosis and the course of respiratory diseases in particular.

Function, effect & goals

Spiroergometry is firmly established in the medical disciplines of cardiology and pulmonology. Spiroergometers can now also be found in many general medicine practices. The test can be performed on both children and adults and can take up to 30 minutes.

During a defined load, for example 10 minutes of a bicycle ergometer at 120 watts, relevant cardiovascular parameters such as pulse, blood pressure or EKG are recorded using body electrodes. These parameters can be viewed and evaluated directly by the doctor in real time. The spirometry measures pulmonary parameters through the breathing mask and therefore allows a direct conclusion about the lung function of a test person.

With this combination of spirometry and ergometry, the current physical performance of a patient can be described very precisely. If you have specific questions about athletic performance or if you have restricted lung function, blood samples can also be taken from the earlobe or fingertip during a spiroergometry. These capillary blood samples can then be tested for lactate or blood gases.

In the case of chronic lung diseases, such as COPD, the oxygen content of the blood usually drops significantly under physical exertion. Spiroergometry is also used to monitor the progress of lung diseases or to monitor therapy. During a spiroergometry, the load is usually continuously increased, so it is also about answering the question of what maximum performance is possible. The organs involved in the provision of the service, in particular the lungs, heart and skeletal muscles, can be assessed in their interaction during the examination.

The doctor can also perform percussion or cardiac auscultation during the spiroergometry. The maneuver is performed either on the treadmill or on a bicycle ergometer. The increase in performance takes place in previously selected load levels. Exhaled carbon dioxide, CO2 and oxygen consumption are measured through the breathing mask. The parameters collected in the process can be compared with a reference table.

Typically, in spiroergometry, in addition to vital parameters such as pulse and blood pressure, respiratory rate, respiratory flow and pulmonary parameters such as one-second capacity and vital capacity are recorded. If the patient reaches the limits of their resilience, the so-called anaerobic threshold is reached. Glucose is then no longer completely burned by the metabolism and lactate is produced as a metabolic product. At the anaerobic threshold, the level of the lactate value provides valuable information on muscular fatigue in connection with an oxygen deficit in lung diseases.

This anaerobic threshold is always the individual endurance limit of a test person. Physical training can influence the anaerobic threshold. If the performance of a patient deviates significantly from the normal values ​​of his gender and his age group, this is due to pulmonary or cardiac causes or a combination of both. Oxygen deficits and thus premature fatigue in spiroergometry can also have completely different causes, for example anemia.

Risks, side effects & dangers

Spiroergometry is often carried out in chronically ill patients to monitor the progress and therefore involves certain risks. Even healthy patients are catapulted to the limit of their individual physical performance. Unforeseen events such as cardiac arrhythmia or hyperventilation can therefore occur during a maneuver.

Spiroergometry should therefore only take place under medical supervision. The German Society for Pulmonary Medicine believes it is mandatory to have an emergency kit with adrenaline, intubation equipment and ventilation mask available during a spiroergometry. In patients with a previous pulmonary burden, such as asthmatics or allergy sufferers, the exposure can also lead to respiratory arrest. The possibility of immediate therapeutic intervention largely minimizes the consequences of such risks and side effects in everyday clinical practice.

Despite the standardized implementation of a spiroergometry, the procedure is by no means free from possible measurement errors. In particular, the frequently occurring hyperventilation is seen as a significant source of error. Even putting on the breathing mask can lead to psychologically triggered hyperventilation in some patients. In the subsequent performance diagnostics, this can lead to incorrect results in the respiratory compensation.

All device parts, i.e. breathing mask or hoses, are reused and must therefore be cleaned and sterilized very carefully. If hygienic requirements for device cleaning are neglected, germ reservoirs can otherwise form unnoticed, which mean a potential risk of infection for the patient.