Gas exchange fault

Gas exchange disturbance is defined as a disturbance of gas exchange triggered by a change in the exchange surface and/or diffusion distance, which primarily leads to improved oxygen saturation in the blood (Schoppmeyer 2020). In the advanced stage, the partial pressure of CO2 may increase and suction may develop. Develop hypercapnia (van Aken 2007).

Pulmonary gas exchange disturbance always leads to hypoxemia (Oczenski 2008).

By means of blood gas analysis, one differentiates between:

- 1. pulmonary partial insufficiency.

In this case, hypoxemia occurs with a drop in the partial (arterial) O2 pressure. The partial pressure of CO2 is normal or decreased, so-called normocapnia or hypocapnia. This is called "respiratory alkalosis" (Oczenski 2008).

- 2. Pulmonary global insufficiency

In pulmonary global insufficiency, there is a drop in the (arterial) partial pressure of O2 and an increased partial pressure of CO2, also known as hypercapnia. In such a case, one speaks of a "respiratory acidosis" (Oczenski 2008).

Gas exchange dysfunction can occur at any age, even in neonates (Oczenski 2008). Classic examples of a gas exchange disorder are pneumonia and respiratory distress syndrome (ARDS) (van Aken 2007).

Gas exchange disorders may include diseases of:

- Lungs

- bronchi (Herold 2022)

- cardiovascular system (Kasper 2015)

Gas exchange disorders can also occur postoperatively, e.g. during cardiothoracic surgery, upper abdominal surgery or posttraumatically, e.g. due to lung contusions (Oczenski 2008).

Gas exchange can be impaired at three functional levels:

- Respiratory pump: This includes bony thorax, respiratory muscles, upper airway and bronchial system.

- Respiratory regulation: A central nervous function

- Gas exchange pathway: This consists of the connection between pulmonary vessels and alveolar space (Classen 2009).

The body itself has several mechanisms to compensate for impaired gas exchange:

- Extraction by the tissues of more oxygen from the blood

- Increase of ventilation

- Increase of cardiac output (Wagner 2015)

Clinically, a gas exchange disorder can manifest itself as

- Dyspnea (Kasper 2015)

- cyanosis

- additional symptoms of the triggering disease may exist (Classen 2009)

A gas exchange disorder can be determined by means of blood gas analysis (BGA). The blood sample is taken capillary, venous or arterial (Oczenski 2008).

Arterial blood gas measurements provide more precise values (Wagner 2015).

In the case of a mild form of gas exchange disorder, correction of the hypoxemia is usually already successful by administering oxygen via a nasal probe. If the alveoli collapse, they can be treated by high inspiratory and expiratory pressures during ventilation (van Aken 2007).

The prognosis depends on the disease causing the gas exchange disorder.

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