Introduction:
Inhalation injury is breathing in or inhalation of smoke, steam, and other harmful substances such as superheated gases or chemicals. The inhaled substance's temperature, composition, and exposure duration determine the injury severity. Such inhalation injuries are most commonly seen in fire accidents. Inhalation of the smoke and its toxic by-products cause significant fire-related deaths. Death is more common when severe skin burn occurs along with inhalation injury. Complications such as carbon monoxide and hydrogen cyanide poisoning, hypoxia (low oxygen levels), and upper airway edema (fluid accumulation and swelling) often make the management of inhalation injuries difficult.
What Are the Types of Inhalation Injuries?
The inhalation injuries include the following:
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Injury due to toxic gases such as carbon monoxide and cyanide.
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Upper airway injuries above the vocal cords due to direct heat or chemicals.
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Lower airway injuries below the vocal cords lead to airway edema (fluid accumulation and swelling in the passage from nose to lungs).
What Happens When We Inhale Poisonous Gases?
Carbon monoxide and hydrogen cyanide are two major poisonous gases commonly found in inhalation injuries. These gases are produced by incomplete combustion and are found in the smoke in fire accidents. Inhaling carbon monoxide is an immediate threat to survivors' lives of severe inhalation injuries. This reduces blood's oxygen-carrying capacity, leading to low oxygen levels in the blood. This results in decreased oxygen supply to the body organs, including the brain. As a result, the tissues and organs get affected and lose their functioning capacity. Headaches, nausea, vomiting, flu-like symptoms, and other changes in the central nervous system are seen initially. As the carbon monoxide levels increase in the blood (greater than 40 percent), the patient shows serious complications such as unconsciousness, seizures, breathing difficulty, and an increased chance of death. The symptoms can vary, and routine examinations and laboratory tests fail to identify carbon monoxide poisoning. Hence, it is essential to check the carboxyhemoglobin (COHb) levels in the blood to diagnose carbon monoxide poisoning.
Hydrogen cyanide is a rapid and potent poison to tissues and cells. The symptoms of cyanide toxicity are vague. Inhaling hydrogen cyanide can cause breathing difficulty, shortness of breath, headache, confusion, giddiness, mucous membrane, and eye irritations. Cyanide toxicity is suspected when lactic acid builds up in the blood despite resuscitation after smoke inhalation. Hydrogen cyanide inhalation can result in heart failure and death if emergency care is not given.
How Do Inhalation Injuries Affect the Patient’s Breathing?
Inhalation injuries to the upper and lower airway damage the patient’s airway. In addition, fluid resuscitation may cause fluid accumulation and swelling (edema) in the passage from the nose to the lungs. Edema blocks the airflow to the lungs and makes breathing difficult. Chemicals such as sulfur oxides and aldehydes damage the epithelial cells of the airway. Sloughing, edema, and inflammation can be seen in the windpipe and its smaller lung branches affected by prolonged exposure. Inhalation injury produces lots of debris in the patient’s respiratory tract. The gas exchange (oxygen and carbon dioxide exchange) in the lungs is also affected. As a result, the patient has severe breathing difficulty and respiratory distress. Special tubes are inserted into the airway (intubation) as early as possible to keep the airway clear during emergency care.
How Are Inhalation Injuries Managed?
1. Airway Management:
Airway management is vital for inhalation injury patients. Emergency interventions are initiated to maintain the airway patent to ensure oxygen supply to the lungs. Care is taken to avoid procedures and administering drugs such as steroids that may complicate subsequent treatment. Patients with cyanide or carbon monoxide poisoning are given humidified 100 % oxygen until the blood oxygen levels become normal. Suctioning of the debris in the respiratory tracts is done frequently and adequately to clear the passage. The emergency personnel assesses the patient’s condition to decide if intubation (inserting a tube to provide oxygen and assist breathing) is necessary. If the patient is unable to breathe or has severe damage and obstruction compromising the airway, intubation is done to save lives.
2. Patient Assessment:
After the patient’s airway, breathing, and oxygenation are assured, the patient’s condition is evaluated to make hospital transfer decisions. Normal oxygen level in the pulse oximeter does not rule out inhalation injury. A chest X-ray is done to look for other injuries and the position of the tubes inserted. More invasive diagnostic tests, such as bronchoscopy, are performed for patients on mechanical ventilation (machine-assisted breathing) to assess the severity of the inhalation injury. The patient is transferred to definitive care without delay.
3. Specific Treatment Initiation Depending on the Cause:
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Carbon Monoxide Poisoning: Patients with carbon monoxide poisoning are given 100 % oxygen until blood carboxyhemoglobin levels normalize.
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Hydrogen Cyanide Poisoning: Hydrogen cyanide poisoning is suspected if the patient does not respond to 100 % oxygen resuscitation measures. Hydroxycobalamin cyanide antidote is used to treat such unresponsive patients undergoing cardiopulmonary resuscitation.
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Inhalation Injury Above the Vocal Cord: Upper airway can get blocked due to edema, swelling, and secretions, and the obstruction can progress quickly. Tubes are inserted into the airway to help oxygen supply and breathing (endotracheal intubation) immediately without any delay. Placing the intubation tubes helps to save lives as it can take several days for the swelling in the airway to come down.
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Inhalation Injury Below the Vocal Cord: Lower airway inhalation injury causes debris, edema, and secretions to the windpipe and its tiny lung branches, affecting oxygen absorption in the lungs (gas exchange). Before transferring the patient, intubation is done to enable breathing and sufficient oxygenation. The patient is monitored carefully to check for the worsening of the symptoms. If the need arises, mechanical ventilation is used in which a machine is used to assist breathing and deliver oxygen.
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Supportive Care: Supportive treatment is initiated to manage the patients. Measures such as drugs, chest physiotherapy, and drainage are taken to clear the airway. Various drugs, such as bronchodilators, are used to treat symptoms such as wheezing.
Conclusion:
Inhaling smoke, toxic gases, and other chemicals can lead to life-threatening injuries. Inhalation injuries are most commonly seen in fire accidents. Inhalation of the smoke and its toxic by-products cause significant fire-related deaths. Inhalation injuries damage the patient’s airway. Edema, debris, and secretions block air passage to the lungs. The patient experiences difficulty breathing and has various symptoms depending on the cause and severity of the injury. Immediate airway management, quick and prompt assessment, and resuscitation are essential to save lives in inhalation injury.
