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Module 14--Current Emergency--Smoke Inhalation:

Terms in this set (17)

--Systemic chemical poisoning due to carbon monoxide should be suspected in every victim of fire and may be confirmed by measuring the serum carboxy-hemoglobin level.

--The often-described cherry-red skin color is not a frequent or reliable finding in patients with carbon monoxide poisoning. Similarly, arterial blood gas measurements are not reliable determinants of carbon monoxide poisoning, because PaO2 and the calculated percentage of oxygen saturation of hemoglobin (the value that is routinely reported by clinical laboratories) are not affected by carboxyhemoglobin. The oxygen saturation measured by pulse oximetry does not distinguish oxyhemoglobin from carboxyhemoglobin. Hence, the actual saturation is obtained by subtracting the percent of carboxyhemoglobin from the measured saturation obtained from the pulse oximeter.

--Typical nonexposed, nonsmoking individuals may have serum carboxyhemoglobin levels of up to 1%; smokers usually have levels of 4-6%. Levels above 10% signify significant exposure.

--Patients may be asymptomatic when carboxyhemoglobin levels are below 10-15%. Levels higher than 50-60% are associated with a high incidence of coma and seizures, and levels higher than 70% are frequently fatal.

--Myocardial ischemia or infarction and cardiac arrhythmias occur frequently, especially in patients with underlying atherosclerotic heart disease.

--Some patients who initially appear to have recovered may experience delayed onset of a neurologic syndrome characterized by dementia, ataxia, and other sensory and motor abnormalities. This syndrome may be due to infarcts in the globus pallidus. Loss of consciousness may be transitory.
--If there are signs of thermal injury to the airway, endotracheal intubation is indicated.

--In patients with major burns (particularly greater than 40-60% total body surface area), even if the airway is patent initially, edema frequently occurs minutes or hours later. Prophylactic intubation prevents a subsequent difficult intubation or surgical airway.

--Obtain arterial blood gas and carboxyhemoglobin determinations in all patients with possible smoke inhalation.

--While waiting for the results, give 100% oxygen by tight-fitting reservoir mask or, if indicated, by endotracheal tube.

--Avoid alkalosis and hypothermia, which decrease the dissociation of carbon monoxide from hemoglobin. Indications for hyperbaric oxygen therapy have been described as a carboxyhemoglobin level greater than 25%, neurologic symptoms, seizures, pregnancy, or depressed consciousness. The efficacy of hyperbaric oxygen in clinical management remains unproved and its use cannot be mandated.

--Although therapy shortens the half-life of carboxyhemoglobin to roughly 20 minutes, the hazards and the length of time involved in transporting a critically ill patient to the nearest hyperbaric oxygen facility and the limited resuscitative environment of the chamber may outweigh the benefits of treatment.

--Hyperbaric oxygenation may be useful in the severely poisoned patient who fails to respond to therapy with 100% oxygen. If carboxyhemoglobin levels are under 2% and if oxygenation is adequate, the inspired oxygen content can be decreased.

--In stable patients with suspected thermal or chemical injury of the airway, evaluate mucosa injury using direct laryngoscopy.

--Obtain an ECG, and monitor cardiac rhythm. Carbon monoxide poisoning is associated with myocardial ischemia and cardiac arrhythmias.

--Obtain a chest X-ray to look for signs of lung injury if smoke inhalation has occurred and to serve as a baseline for further changes. Give inhaled and parenteral bronchodilators to patients with clinical evidence of bronchospasm.

--Obtain a urine specimen for assessment of myoglobinuria.

--No evidence supports the use of prophylactic antibiotics or systemic corticosteroids in the treatment of inhalation injuries.