Pulmonary embolism
In acute pulmonary embolism, a vessel in the lung is displaced by a blood clot. A lack of oxygen in the blood of the patient can be detected here. Since the patient no longer has sufficient oxygen, he breathes more frequently.
However, this hyperventilation usually causes a drop in the carbon dioxide concentration, which is exhaled with each breath. In about 20% of the patients, however, these constellations do not occur; normal oxygen partial pressures are found in the blood. Especially if one has only a low cardiac output (blood volume transported by the heart per minute), it can remain at a normal distribution in the arterial blood gas analysis.
If the oxygen partial pressure in the arterial blood gas analysis increases, this can be an indication of a deteriorating blood circulation situation of the patient. In individual cases, falling values can also indicate an improvement in pulmonary perfusion. If the patient is known to have cardiovascular diseases, the diagnosis of pulmonary embolism can be made considerably more difficult.
Overall, a blood gas analysis alone is not sufficient for the diagnosis of a pulmonary embolism. Clinical symptoms such as shortness of breath, palpitations, chest pain, etc. and other diagnostic means (ECG, X-ray thorax, D-dimer test, CT or MR imaging of the vessels) must always be taken into account.
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