What is measured?
Ergometry records the following data: In addition, hemodynamic (blood vessels), pulmonary (lungs) and metabolic (metabolism) parameters are determined. An additional measurement of the respiratory gases (spiroergometry) allows insight into processes of energy metabolism.
- Heart Rate
- Blood pressure
- Exercise ECG
- Respiratory frequency
- Respiratory minute volume
- Oxygen concentration
- Carbon dioxide concentration
- Subjective perception of performance
- Achieved power (mostly in watts or km/h)
Procedure
Before every ergometry recording, the patient should be examined and asked about current complaints. Particular attention should be paid to the heart and lungs in order to rule out possible pre-existing conditions that do not allow an ergometric examination. Furthermore, it is advisable to ask about the patient’s medications (e.g. beta blockers), as these could influence the result of the ergometry in both positive and negative ways.
The determination of height, sex and age is also important for the later evaluation. Before the ergometry under stress starts, an ECG should be written and the blood pressure measured under resting conditions. This gives an initial value for comparison with the newly determined values.
The examination conditions are equally important. A room temperature between 18 and 22 °C is desirable. The humidity should also not be too high.
In addition, it should be ensured that the physician and/or the personnel performing the ergometry can/can intervene and act in an emergency. Now the patient is equipped with all necessary means for monitoring the individual values.These include a 12-channel ECG (including chest wall and arm and leg leads), a blood pressure cuff and optionally a respiratory mask, which is used to record lung function, the so-called spiroergometry (i.e. respiratory volume, respiratory rate, etc.) In the course of the examination there are basically two different procedures for performing ergometry.
On the one hand, one can aim for a continuous load at a constant level, in which a certain power (in watts) is prescribed for a certain time, which is terminated after it has been successfully achieved. On the other hand, starting from a certain load, it is possible to gradually increase the load at regular intervals until the patient’s continuous output limit is reached. This corresponds to the exhaustion of the patient.
Usually one starts at 25 or 50 watts and increases the power by 25 watts every two minutes. For very athletic test persons, the power can also be increased by 50 watts every three minutes. On the whole, the total duration of exercise should not exceed 12 minutes.
The maximum pulse limit is calculated using the formula “220 – age” and should not be exceeded during the stress test. The procedure is slightly different for treadmill ergometry. Here you start with a rest phase of three minutes and increase the load in eight steps every three minutes with increasing speed and/or larger inclination angle.
Before, during and after the exercise the following changes in the patient should be observed: the skin color of the patient, his sweat production, possible pain, shortness of breath, signs of exhaustion and other abnormalities. In addition, it is very important to record parameters such as pulse (continuously), blood pressure and ECG readings at minute intervals. The ergometry can only be completed when all values are back to normal after a recovery phase as a result of the stress.
