SUMMARYInhalation injury is an acute insult of the respiratory tract, caused by steam or toxic inhalants. A suspicion of inhalation trauma (closed-space exposure, facial burns, etc.) is an indication for an immediate endotracheal intubation.Precise objective case history is also very important point for making the diagnosis. Up-to-date methods of examination in case suspicion of inhalation injury are described in our contribution.The main therapeutical points are mentioned as well.
Das Inhalationstrauma
Kaloudovä Y., Brychta P., Aihovä H., Suchänek 1., Hrubä J., Seidlovä D., Hrazdfrovä A., Kubälek V.
Die Inhalationsverletzung ist eine akute Beschädigung des Respirationstraktes, die durch Dampf oder toxische Inhalation verursacht wird. Der Verdacht auf das akute Inhalationstrauma (Bedrohung in einem verschlossenen Raum, Gesichtsverbrennungen usw.) stellt eine Indikation für die sofortige Endotrachealeintubation dar. Für die richtige Diagnose ist die präzise und objektive Anamnese das wichtigste. Im unseren Beitrag werden die Untersuchungsmethoden der Fälle mit Verdacht auf eine Inhalationsverletzung beschrieben. Es wird auch das Haupttherapeutischeverfahren erwähnt.
Key words: inhalation injury, lung oedema, respiratory insufficiency in burns, bronchoscopy in burns
Inhalation trauma may be defined as an acute damage of the respiratory tract caused by the inhalation of combustion products or steam, as a rule in a closed space.
lt is a combination of damage to the epithelium of the airways by heat or chemicals, or it is a systemic intoxication by the products of combustion.
Combustion products comprise a mixture of not air, solid particles dispersed in the air (with an irritating and cytotoxic effect), aerosols of irritating and cytotoxic fluids and toxic gases with a systemic action (e.g. CO).
Solid particles larger than 10 micrometres are retained in the nose and nasopharynx, particles 3-10 micrometers in the tracheobronchial tree. Particles of 1-2 micrometers pass into the alveoli.
Acta chirurgiae plasticae
Gases readily soluble in water react chemically in the upper airways, less hydrosoluble gases in the lower airways. Gases poorly soluble in water penetrate through the alveolocapillary barrier and their toxic effects are systemic.
Direct necrosis of the epithelial cells, impaired function of the mucociliary apparatus, an acute inflammatory reaction with stimulation and passage of pulmonary macrophages and activation of neutrophils at the site of the insult occur. Liberation of oxygen radicals and tissue proteases, cytokines and smooth muscle constrictors (thromboxane A2, C3A, C5A) occurs and, secondarily increasing ischaemia in the already damaged airways (development of oedema of the wall, impaired microcirculation). The resistence of the wall of the airways and of the pulmonary vessels increases; the pulmonary compliance by formation of the interstitial pulmonary oedema declines. Oedema of the wall of the lower airways
occurs as well as formation of plugs in the airways made up of necrotic epithelial cells, mucus and blood cells. Thus, partial or total obstruction of the lower airways develops. Distally from the obstruction atelectasis may develop or conversly excessive dilation of the pulmonary alveoh. This may result in respiratory failure and hypoxaemia.
After exposure to products of combustion, reaction occurs at three levels:
1. Supraglottic region: The latter responds by the rapid development of oedema (within several minutes to three days). Supraglottic damage develops in some Gases independently, more frequently after skort-term exposure to combustion products of higher temperature, in particular when at the time of the injury reflex closure of the glottis occurs.
Symptoms: hoarseness, tendency to cough, respiratory insufficiency, imminent laryngospasm (Fig. 1).
<% immagine "Fig. 1","gr0000036.gif","Supraglottic region - pathophysiology; respiratory insuficiency 5th hour - 3rd day.",230 %>2. Tracheobronchial damage: Slower development of oedema. Greater risk of development of ARDS and pneumonia, imminent bronchospasm.
Symptoms: urge to cough, bronchorrhoea, sings of respiratory insufficiency usually appear the third to fifth day (Fig. 2).
<% immagine "Fig. 2","gr0000037.gif","Tracheobronchial region - pathophysiology; respiratory insuficiency 3rd - 7th day postburn.",230 %>3. Intoxication by combustion products (most frequently carbon monoxide): Carbon monoxid is linked very actively to haemoglobin and thus takes up the binding sites for Oxygen. The transport capacity of haemoglobin for Oxygen is impaired even in the Gase of good partial Oxygen pressure in arterial blond and this results in hypoxia.
In case of explosion the Situation is complicated by the effects of the pressure wave - barotrauma may develop with rupture of some part of the pulmonary tree, in particular the pulmonary alveoli. Costal fractures may also occur or the development of pneumothorax and haemothorax.
A wide range of damage at different levels of the airways, possible intoxication and development of respiratory failure within the range of 5 hours to 7 days after injury makes the assessment of the diagnosis and therapy of Inhalation injury rather complicated.
Accurate objective Gase - history is very important (mechanism of injury, exposure to combustion products in closed space, type of burning material).
Up-to-date methods of examination in Gase of suspicion of Inhalation injury are: auscultation, direct laryngoskopy, X-ray of the Jungs (usually 3-5 days normal finding), repeated fiberoptic bronchoscopy, laboratory screening including level of carbonyl haemoglobin and examination of blond gases - pulmonary shunts (Tab. 1).
Toxicological examination, in certain Gases even the radioisotope examination of the Jungs. Radioisotope examination is useful but in many departments not yet available.Functional examination of the Jungs is usually done.
Cytokine levels and cytological examination of broncho-alveolar lavage are examined at present more often experimentally as an indicator of risk (Figs 3, 4).
<% riquadro "Bronchoscopic fmdings:
• soot
• hyperaemia, bronchorrhoea
• petechiae
• pink-grey areas of necrosis
• flat, sometimes concave rigid areas of white totally necrotic lining econdary infection - mucopurulent secretion" %>
Treatment of patients with Inhalation injuries involves supportive treatment apart from the specific treatment of some intoxications.In the majority of Gases, Inhalation trauma is associated with extensive dermal bums.
Immediately after injury and on admission to a specialised department, basic measures are essential to take:
1. Ensuring free airways - prompt endotracheal intubation:In case of deep skin burns on the neck and trunk, releasing incisions must be made as soon as possible.
2. Ensuring adequate ventilation and oxygenation of peripheral tissues: moistened oxygen, artificial pulmonary ventilation in case of respiratory insufficiency.
Sings of respiratory insufficiency:
Ventilation regimen strictly individual as required. At present, in the majority of departments tolerance of permissive hypercapnia is preferred or even permissive hypoxaemia, provided the circulatory stability of the patient is preserved. Ventilation parameters should be close to the following values:
For the vitality of peripheral tissues in cases of circulatory stability the following are sufficient: Sa02 > 0.9, pH > 7.21.
3. The treatment of shock, involving haemodynamic stabilization of the patient (Koller, 1992), it means adequate intravenous volume resuscitation as a prevention of hypovolaemic shock. In inhalation trauma, during the first 24 hours the need of crystalloids is 40-75 % greater than in patients with dermal burns only.
4. Careful analgosedation is essential.
5. After intoxication with combustion products: specific antidotes (if known) and oxygen therapy.
6. Promotion of mobilization and evacuation of secretions and detritus from the tracheobronchial tree and lungs (airway suction and lavage, humidification, chest physiotherapy, regular positioning of the patient, mucolytics, bronchodilatating substances).
7. Antioedematous treatment (elevation of head and trunk on the bed, escinum etc.).
8. Other problems of pharmacotherapy: In many departments a major single dose of corticosteroids is administered immediately after injury to mitigate the cascade of mediators of an acute inflammatory reaction and to reduce the level of circulating mediators. Substitution of surfactant should be considered. Nonsteroidal antiphlogistics are also administered even at the present time to patients with inhalation injuries.
| <% immagine "Fig. 3","gr0000038.jpg","The bronchoscopy of a 51- H20,-year-old male third day after inhalation of products of combustion in a closed space.",230 %> | <% immagine "Fig. 4","gr0000039.jpg","The cytological picture shows a markedly increased quantities of polynuclears. The polynuclears are degenerated, with gramentose nuclei, macrophages are also present, together with desintegrated and structurally altered cylindrical epithelia. (MGG, 40x)",230 %> |
Yvona Kaloudovä Burn and Reconstructive Surgery University Hospital Jihlavshä 20 624 00 Brno-Bohunice Czech Republic
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