We are presenting cases of 2 employees of a chemical plastics manufacturing plant who experienced acute, brief, inhalational exposure to lethal concentrations of hydrogen sulfide in a confined space. Eight other coworkers not present in the immediate exposure area also presented to local health care facilities with mild complaints of headache, nausea, and dizziness, but they suffered no significant sequelae.Patient #1 was a 55-year-old man who, while working in a confined space, uncoupled a nozzle from a steam pipe, collapsed within one minute, and suffered cardiopulmonary arrest. He had a prior history of asthma, hyperlipidemia, coronary artery disease, and was taking lisinopril, aspirin, and lipitor. Following chest compressions and rescue breathing, both by on-scene responders and EMS, the patient's blood pressure was 210/110 mmHg, the pulse was 100 bpm, and ventilation was assisted at 14/minute. On examination, the patient was minimally combative, with a Glasgow coma score of 6 (E1, V1, M4), with pupils 3 mm bilaterally and reactive to light. The patient had a small partial-thickness burn to the right chest, presumed to be a thermal burn from steam or the hot pipe. No cyanosis or pulmonary crackles were noted. Because of respiratory distress, the patient was intubated on-scene using fentanyl, diazepam, and vecuronium by the combined nurse-physician Air EMS flight team. Post-intubation vital signs were as follows: blood pressure 130/69 mmHg, pulse 95 bpm, respirations 14/min (assisted), and oxygen saturation 98% on 100% FiO 2 . The patient's temperature on arrival to the Emergency Department (ED) was 98.2°F (36.8°C), where his examination remained unchanged.Diagnostic studies were obtained in the ED. Arterial blood gas analysis on 100% O 2 showed: pH 7.24, pCO 2 58 mmHg, pO 2 284 mmHg, oxyhemoglobin 97.2%, deoxyhemoglobin 2.0%, methemoglobin 0.3%, and carboxyhemoglobin 0.0%. The blood appeared red. An electrocardiogram revealed a narrow complex tachycardia, without Q waves, ST-segment abnormalities, or interval changes. Serum chemistries were as follows: a sodium of 139 mEq/L, potassium of 4.2 mEq/L, chloride of 105 mEq/L, bicarbonate of 25 mEq/L, BUN of 15 mg/dL, creatinine of 0.9 mg/dL, and glucose of 156 mg/dL. Creatinine kinase (CK) was 299 IU/L, CK-MB 2.2 IU/L, and troponin-I was 0.05 IU/L. A complete blood count showed: white blood cells at 9.0 k/mm 3 , hemoglobin at 13.0 g/dL, hematocrit at 38.2%, and platelets at 130/mm 3 . Coagulation studies were normal, and a chest radiograph showed adequate endotracheal tube placement, absence of pulmonary edema, and a widened mediastinal silhouette, likely due to projection artifact on an antero-posterior film.Patient #2 was a 53-year-old male co-worker, with a history of hypertension, but he was not receiving medical therapy. He was
