Phosgene (carbonyl chloride) gas is of historical interest and has important industrial applications today. Historically, it was the most lethal of World War I war gases. It is estimated that nearly 80% of the poison gas deaths during that war were caused by phosgene exposure. In the post 9/11 era, phosgene remains a potential, highly toxic chemical weapon. Additionally, phosgene poses significant risk to some workers who may be occupationally exposed. This case report demonstrates a known hazard of refrigeration workers suffering phosgene poisoning after heating chlorinated fluorocarbons (Freons).
49 year-old refrigerator technician was admitted to our intensive care unit following phosgene gas exposure. The patient reports using a welding torch while soldering a refrigerator coil which contained Freon. Following vaporization of Freon to phosgene the patient immediately noted a peculiar, pungent smelling gas. He then experienced lacrimation and a burning sensation in his mouth and throat, followed by severe dyspnea, wheeze and cough. On arrival to the emergency department the patient was dyspneic and complained of chest tightness and palpitations. The patient’s heart rate was 140 bpm, blood pressure was 110/60, oxygen saturation was 98% on a non-rebreather facemask. Physical examination revealed an obese male in moderate distress. His conjunctiva was injected. His respirations were mildly labored but clear to auscultation. The cardiovascular exam was irregularly irregular. The remainder of his exam was normal. Chemistries and complete blood count were within normal limits. An arterial blood gas revealed a pH of 7.39, pCO2 of 36 mmHg, and pO2 of 92 mmHg on a FiO2 of 1.0. The patient’s chest X-ray was normal and telemetry monitoring showed a ventricular rate of 140 bpm and atrial fibrillation. Following CDC and OSHA recommendations, appropriate measures were taken to minimize risk of poisoning hospital personnel including monitoring of the patients exhaled gas phosgene levels. This remained detectable (>1 ppm) for approximately 5 hours, after which isolation procedures were discontinued. The patient was admitted to the ICU for observation with rapid resolution of hypoxic respiratory failure and was discharged within 48 hours.
This patient’s symptoms were typical of those seen after exposure to phosgene at a concentration exceeding 3 ppm. 1 The possibility of occupational exposure of refrigeration workers to phosgene has been rarely reported. Adequate purging of refrigeration pipes before welding should help to reduce this risk significantly. Phosgene is a highly toxic gas, and exposure may have a fatal outcome. Respiratory symptoms may be delayed by a latent period of several hours before acute respiratory distress syndrome (ARDS) becomes apparent. The mechanisms of lung injury have been elucidated in animal models to include acylation and lipid peroxidation. These processes result in denaturation of proteins and lipids, irreversible alterations of membrane structures, and disruption of enzyme and other cell function. 2 Treatment is primarily supportive as there is no known antidote for phosgene. The most severe cases benefit from close monitoring and positive pressure ventilation, but the role of corticosteroids and other adjuncts of care remain controversial. Specific treatment regimens for phosgene exposure and ARDS have not been investigated in human, prospective randomized controlled trials.
Phosgene exposure is associated with significant morbidity and mortality. Physicians should be aware of the risk of phosgene exposure when heat is applied to Freon, commonly used in a variety of industries. Patients with a history of exposure should be admitted to the hospital for observation given the potential for delayed onset of respiratory failure and ARDS.
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