Air trapping
The Pschyrembel defines air trapping as follows: "Compression of the small airways (bronchial collapse) through a strong increase in intrathoracic pressure with forced expiration, whereby air remains trapped in the alveoli distal to the compressed bronchi or bronchioles (so-called trapped air)." However, this definition only takes into account a few pathophysiological aspects of air trapping; ultimately the definition of the term is inconsistent. "Air trapping" is generally used in medical parlance to describe a process in which there is a pathological accumulation of air in distal sections of the airway system, which does not exhale or only exhales under difficult conditions can be. This can also be the case, for example, if air is in the alveoli after inhalation, but can no longer be exhaled due to mucus or cramps in the bronchial system. Air trapping is therefore also possible with normal breathing and not only with forced expiration.
Emergence
Anatomical changes, constrictions and adhesions that enable air trapping can be caused by various diseases. These include colds , bronchitis , asthma , allergies , chronic obstructive pulmonary diseases or pulmonary emphysema . In emphysema, for example, air collects in the emphysema bladders and cannot be completely exhaled due to the narrowed bronchial system. In bronchial asthma , too, caused by a narrowing of the bronchi, the exhalation of the air "trapped" in the alveoli is impeded . This leads to reversible or "dynamic" lung hyperinflation.
Symptoms and Dangers
If only individual, smaller areas in the lungs are affected, local air trapping, for example in a small emphysema bubble, can go completely unnoticed by the patient and remain asymptomatic. With increasing severity of the underlying disease, the symptoms can increase to life-threatening conditions: The over-inflated sections can press on the surrounding tissue sections of the lungs and there in turn compress the airways, so that there is also a narrowing (obstruction) of the airways there. In addition, the trapped air can no longer participate in the gas exchange, so that the person concerned feels short of breath. This leads to an accelerated pulse ( tachycardia ). Lack of oxygen can lead to cyanosis (blue discoloration of the skin and mucous membranes). In severe lung hyperinflation, the diaphragm is pressed down and flattens out. This restricts the mobility of the lungs and makes breathing even more difficult. In addition, the ribs are in an increasingly horizontal position ( barrel chest ). The pressure in the pulmonary circulation increases, which leads to congested neck veins. Chronic hyperinflation can u. a. cause damage to the heart via this mechanism . Those affected often take a seated posture that makes breathing easier ( coachman's seat ) in order to improve the use of the auxiliary breathing muscles .
If the extensibility of the lung tissue is exceeded, the lung tissue ruptures. This can e.g. B. occur due to an acute pressure increase in the airways such. B. a strong cough or rapid compression of the thorax from outside (steering wheel impact, kick, etc.). A feared consequence is the pneumothorax .
Special dangers when diving
The (undetected because unnoticed) air trapping is particularly dangerous when diving, as the air that is inhaled under increased pressure in the depths expands during the surface. Since the air - for example in an emphysema bladder - is "trapped", i.e. can only be exhaled with a very delay, the volume expands when the surface is too rapid and can lead to overstretching and even tearing of the lung tissue. In this case, one speaks of pulmonary barotrauma (PBT) . Depending on the location of the emphysema bladder, this can result in both a pneumothorax and an arterial gas embolism (AGE) . The principle is not limited to diving, but can be applied to all conditions in which there is a rapid drop in ambient pressure, for example also in the event of an accident on overpressure construction sites in tunnel construction.
activities
Air trapping is not an independent clinical picture, but a process that can occur as a result of various diseases. However, there is one thing in common that air can no longer be exhaled. The therapeutic measures are therefore aimed at improving lung ventilation. This is done on the one hand through first aid measures such as a sitting posture to facilitate breathing to mobilize the auxiliary breathing muscles and the use of the lip brake , as well as through drugs that expand the bronchial system. Oxygen administration is mostly indicated, but should be done with caution in patients with chronic oxygen deficiency, as they can be sensitive to oxygen administration. In the event of severe respiratory distress, the rescue service including an emergency doctor must be called in. In the special case of a diving accident, first aid measures are the earliest possible administration of the maximum dose of oxygen and fluids. After alerting the rescue service, a diving doctor hotline should be contacted for further advice.
Note: In contrast to statements in an earlier version of this article, air trapping is not to be equated with barotrauma of the lungs , but rather a risk factor for this.
Individual evidence
- ↑ Willibald Pschyrembel: Pschyrembel Clinical Dictionary: With clinical syndromes and nouns anatomica. 266th edition. Walter de Gruyter & Co, Berlin 2014.
- ^ S. Matsuoka, Y. Kurihara, K. Yagihashi, M. Hoshino, N. Watanabe, Y. Nakajima: Quantitative assessment of air trapping in chronic obstructive pulmonary disease using inspiratory and expiratory volumetric MDCT. In: AJR Am J Roentgenol. doi: 10.2214 / AJR.07.2820
- ↑ U. Joseph Schoepf: Expiratory Hyperinflation - Air Trapping. In: Multidetector-Row CT of the Thorax. Birkhäuser, 2005, ISBN 3-540-26247-4 , p. 101.
- ↑ Guideline diving accident . Society for diving and hyperbaric medicine (GTÜM), AWMF register number 072-001, created on October 1, 2014, valid until October 31, 2017, S2k classification , accessed on August 2, 2017 (PDF).
