Respiratory compensation point | Spiroergometry

Respiratory compensation point

The attainment of the anerobic threshold can also be estimated, for example, on the basis of the respiratory compensation point. From this point on, significantly more CO2 is breathed out than before as the physical strain continues to increase. This is due to the fact that anaerobic energy production leads to increased lactate formation and acidosis.

This leads to an increase in the respiratory drive (hyperventilation). The increased respiration in turn leads to a stronger exhalation of CO2, which can be measured in the breathing air by spiroergometry. Thus, RCP is not quite equivalent to the anaerobic threshold but marks a point just before reaching the anaerobic threshold.

Once the RCP is reached, the oxygen uptake is submaximal rather than maximum. This range is called the continuous power limit. A load in this range can be continued without rapid muscular fatigue.

Termination criteria

Spiroergometry is widely used in the work with top athletes. However, it is also used in everyday clinical practice with patients, especially in cardiology (heart specialist area) and pulmonology (lung specialist area). Here in particular, all the more attention must be paid to potential performance limitations of the patient and any signs of physical overstrain. Among the criteria for termination during spiroergometry are that the patient should indicate a sudden feeling of tightness or pressure on the chest (angina pectoris) or that the ECG should show signs of reduced blood flow to the heart (ischemia) or cardiac arrhythmia. Signs of respiratory insufficiency, cold sweat or dizziness should also cause the examination to be aborted.

Contraindications

Spiroergometry is an examination that is associated with considerable physical strain. In this respect, it must first be determined whether the patient suffers from a disease that does not allow such stress. This includes: For patients who are chronically ill but still have a medium level of stress, the stress level must of course be individually adapted to their ability to cope with stress.

  • An acute heart attack
  • An infection (for example a pneumonia)
  • A pronounced narrowing of the aortic valve of the heart (severe aortic valve stenosis)
  • A severe heart failure (cardiac insufficiency)
  • Acute respiratory insufficiency
  • An acute thrombosis (blood clot, for example in the lower leg).