Spiroergometry: Treatment, Effects & Risks

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

What is spiroergometry?

During spiroergometry, the patient is subjected to continuous exercise, for example on a treadmill, and breathing is monitored in parallel using a mask developed specifically for this purpose. Spiroergometry is a compound term made up of 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 subjected to continuous exertion, for example on a treadmill, while breathing is monitored using a mask developed specifically for this purpose. In addition, an electrocardiogram can also be derived, so that spiroergometry as a whole allows conclusions to be drawn about the performance and reaction of the metabolism, respiration, heart and circulation under stress. The level of stress is determined by the physician, because the patient should not be put at risk to his or her health by excessive stress during the maneuver. During spiroergometry, also known as ergospirography or ergospirometry, certain parameters, i.e. measured values, are continuously collected, which are of high importance for the diagnosis and progression of respiratory diseases in particular.

Function, effect, and goals

Spiroergometry is firmly established in the medical disciplines of cardiology and pulmonology. Spiroergometers are now also found in many general medical practices. The examination can be performed on both children and adults and can last up to 30 minutes. During a defined load, for example 10 minutes of bicycle ergometer at 120 watts, relevant cardiovascular parameters, such as pulse, blood pressure or ECG, are recorded by means of body electrodes. These parameters can be viewed and evaluated in real time directly by the physician. Spirometry measures pulmonary parameters through the breathing mask and therefore allows direct conclusions to be drawn about a subject’s lung function. This combination of spirometry and ergometry can therefore provide a very accurate description of a patient’s current physical performance. For special questions regarding athletic performance or limited lung function, blood samples can also be taken from the earlobe or fingertip during spiroergometry. These capillary blood samples can then be analyzed for lactate or blood gases. In chronic lung diseases, for example COPD, the oxygen content of the blood usually drops significantly during physical exertion. Spiroergometry is therefore also used to monitor the progress of lung diseases or to monitor therapy. During spiroergometry, the load is usually increased continuously, so it is also a question of answering the question of what maximum performance is possible. The organs involved in the performance, in particular the lungs, heart and skeletal muscles, can be assessed in their interaction during the examination. Percussion or cardiac auscultation can also be performed by the physician during spiroergometry. The maneuver is performed either on a treadmill or a bicycle ergometer. The power increase takes place in previously selected load levels. Exhaled carbon dioxide, CO2, and oxygen consumption are measured through the breathing mask. The parameters obtained can be compared with a reference table. Typically, spiroergometry records vital signs such as pulse and blood pressure, as well as respiratory rate, respiratory flow, and pulmonary parameters such as one-second capacity and vital capacity. If the patient reaches the limits of exercise capacity, 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. The level of lactate at the anaerobic threshold provides valuable information about muscular fatigability in conjunction with an oxygen deficit in lung diseases. This anaerobic threshold is also always the individual continuous performance limit of a subject. The anaerobic threshold can be influenced by physical training.If a patient’s performance deviates significantly from the normal values for his or her gender and age group, this is due to pulmonary or cardiac causes or a combination of both. However, oxygen deficits and thus premature fatigability on spiroergometry can also have entirely different causes, such as anemia.

Risks, side effects, and hazards

Spiroergometry is often performed on chronically ill patients to monitor their progress and therefore carries certain risks. Even healthy patients are catapulted to the edge of their individual physical capacity. Unforeseen events such as cardiac arrhythmias or hyperventilation may therefore occur during a maneuver. Spiroergometry should therefore only take place under medical supervision. The German Society of Pulmonary Medicine considers the provision of an emergency kit with adrenaline, intubation equipment and a ventilation mask to be indispensable during spiroergometry. Patients with pulmonary preload, for example asthmatics or allergy sufferers, can also suffer respiratory arrest during the stress. The possibility of immediate therapeutic intervention largely minimizes the consequences of such risks and side effects in everyday clinical practice. Despite the standardized performance of spiroergometry, the procedure is by no means free of possible measurement errors. In particular, hyperventilation, which occurs frequently, is considered 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 falsified results in respiratory compensation. All parts of the device, i.e. breathing mask or tubing, are reused and must therefore be carefully cleaned and sterilized. Otherwise, if hygienic specifications for device cleaning are neglected, reservoirs of germs can form unnoticed, posing a potential risk of infection for patients.