The symptoms of acute respiratory failure are stage-specific. In stage 1 there is a lack of oxygen in the blood (=hypoxaemia) and an increased respiratory rate (=hyperventilation). This leads to shifts in the acid-base balance, the pH rises (= respiratory alkalosis).
In stage 2, respiratory distress increases more and more and spotty, streaky densifications of the lungs appear, which become visible in the X-ray image. In stage 3, in addition to hypoxaemia, an increase in the carbon dioxide content occurs (=hypercapnia), as the CO2 can no longer be breathed out sufficiently. This is called respiratory global insufficiency and is characterized by a decreasing pO2 and an increasing pCO2. The acid-base balance shifts to an acidic pH, resulting in respiratory acidosis. The X-ray image now shows shadows on both sides.
X-rays are taken to monitor the progress of acute lung failure. In the same way, blood gas analysis (blood sample taken from the earlobe) is required to monitor the acid-base balance. In the case of acute lung failure, lung function shows early signs of a decrease in the lung’s ability to absorb oxygen (=diffusion capacity) and a decrease in lung expandability (=compliance). A cardiac echo is performed to rule out heart disease. To make a diagnosis, 3 criteria must be met:
- Presence of a trigger factor
- Hypoxemia that does not respond to therapy
- Detection of lung changes in the X-ray image that are not due to cardiac pulmonary edema.
If possible, the cause of the acute lung failure should be eliminated, e.g. circulatory shock. Subsequently, symptomatic therapy is administered. Due to the increasing shortness of breath, patients must be ventilated.
However, since normal ventilation would damage the lungs, lung protective ventilation is used (acute lung failure). This consists of low peak pressures and low breathing volumes. This is combined with a positive pressure at the end of exhalation (= expiratory pressure, PEEP).
As soon as the patient breathes spontaneously, assisted spontaneous breathing techniques (such as BIPAP or APRV) are used. Alternatively, a machine that eliminates CO2 outside the body (=extracorporeal) via a venovenous dilatation of the circulation and enriches the blood with oxygen can be used, a so-called EKMO (extracorporeal membrane oxygenator). In severe cases the patient is placed in a prone position or in a special bed with continuous 60° rotation.
This is a supporting measure to improve the oxygen distribution. The patient must be fed enterally. Complications, such as infections, are treated with antibiotics.
Artificial coma for acute lung failure
In acute lung failure, the lung is suddenly no longer able to supply the body with sufficient oxygen. This leads to a life-threatening situation that requires very extensive therapy in the short term. In these cases the lung needs strong mechanical support to ensure the survival of the affected person.
According to the current state of medical knowledge, ECMO (extracorporeal lung membrane oxygenation) is usually used for this purpose. The oxygen-deficient blood of the affected person is fed out of the body into the machine. There it is enriched with oxygen (replenished) and then returned to the body.
Since the method is highly invasive, i.e. it intervenes heavily in the human body’s system, affected persons are usually put into an artificial coma for this purpose. In the meantime, however, there are also more and more waking EMOS. Here, the affected person is conscious, can eat, drink and speak and rehabilitation measures such as light muscle training can be started more quickly. Artificial coma for pneumonia