As apnea or apnea ( [ Apno ː ə ], from Greek ápnoia ἄπνοια, non- breathing ' to pnoe πνοή, breathing ', ' breath ') refers to a more or less long exposure of the external respiration. Likewise, the deliberate stopping of breathing is called apnea or apnea (see apnea diving).
The duration of respiratory arrest can be from a few seconds to several minutes. Several different lengths of time, the patient unnoticed apneas per night is the eponymous symptom of sleep apnea syndrome.
Possible causes of respiratory paralysis may come into question:
- Damage to the respiratory center,
- Paralysis of the respiratory muscles,
- Airway obstruction,
- Neurological disorders,
- Trauma, especially a chest compression as a result of an accident or after an avalanche,
- Intoxication ( for example, with potassium cyanide ) or
- Result of a spillage in a mining accident.
The volume of gas contained in the lungs initially remains unchanged. The gas exchange within the lungs and cellular respiration remain of an apnea initially unaffected. Respiratory arrest leads regardless of the cause in a very short time to a dangerous lack of oxygen in the blood ( hypoxemia ) as a consequence it can quickly lead to a further loss of important vital functions. Respiratory arrest leading to the oxygen supply of the brain.
Respiration and CO2
Untrained people can their breath does not last longer than a minute or two willingly. The reason for this lies in the very strict regulation of CO2 and blood pH by the respiratory center. In apnea, no more CO2 is exhaled; it accumulates in the blood. This strong stimulus to the respiratory center may be voluntarily overcome. Trained free divers can hold their breath for over 10 minutes.
In the blood dissolved CO2 in physiological and slightly increased concentration activates the respiratory center of the brain. In contrast, significantly higher concentrations it leads to the reduction or abolition of the reflex respiratory stimulus may lead to respiratory arrest. Risk of poisoning by carbon dioxide.
Since the gas exchange between the blood and lung content is independent of the flow of gas between the lungs and the outside air, can even be administered to a person apneic sufficient oxygen. This phenomenon is called Apnoei oxygenation. In the apnea is of the gas volume in the lungs more oxygen than carbon dioxide is absorbed in the lungs diffused. With open airway administered a gas following the pressure gradient of the upper respiratory tract into the lungs. Upon administration of pure oxygen it is sufficient to fill the oxygen store in the lung. The uptake of oxygen into the blood thus remains in the normal range. However, in an apnea no CO2 is exhaled. The partial pressure of carbon dioxide in the blood will therefore rise and cause a respiratory acidosis. In addition, the oxygen in the lungs will gradually be replaced by CO2.
Under ideal conditions - that is, if before the start of apnea, pure oxygen was breathed to remove all the nitrogen and pure oxygen is insufflated - a healthy adult could theoretically be supplied for one hour with sufficient oxygen. The limiting factor here is the accumulation of carbon dioxide.
Apnoei oxygenation is applied in thoracic surgery as well as manipulations of the airways such as bronchoscopy, intubation, or surgical intervention. Due to the limitations described apnea oxygenation, however, is inferior to the method of extracorporeal circulation and is used only in emergencies and for short operations.
Apnea test ( brain death diagnosis )
The so-called " apnea test " in addition to angiography, electroencephalography, and other one of the criteria that will be used for the determination of brain death in the context of organ donation. Here, the comatose patient is ventilated with pure oxygen and the mechanical ventilation drastically reduced so that there will be an increase in the carbon dioxide partial pressure in the blood. For the receptors in the brain stem, this increase represents a maximum incentive to initiate a spontaneous breath not represent Sets the spontaneous breathing at a fixed threshold value that can be assumed by a complete failure of the respiratory center.
Apnea ventilation is also called backup ventilation ( here varied the names of the various manufacturers of ventilators ).
Spontaneous (or augmentane ) ventilation modes assist the patient to take over completely in breathing without it. As security, apnea setting is used on the ventilator, should fail the spontaneous breathing of the patient, the machine automatically jumps to the mode apnea, so ventilation controlled (or mandatory ) on.
- Pathological breathing type
- Diving Medicine