Successful treatment of severe ARDS caused by accidental inhalation of nitric acid fumes with veno-venous ECMO: A case report and literature review

Abstract

Rationale: The treatment of severe acute respiratory distress syndrome caused by accidental inhalation of nitric acid fumes is challenging. Few successful cases have been reported in literature. Owing to the development of extracorporeal life support, extracorporeal membrane oxygenation (ECMO) may play an important role in treatment.

Patient concerns: A 40-year-old man was accidentally exposed to nitric acid fumes for 10 minutes in a factory. Mild throat irritation and dyspnea occurred 3.5 hours after exposure. Severe dyspnea recurred approximately two hours later. Chest computed tomography revealed bilateral interstitial edema. Tracheal intubation and mechanical ventilation were provided when the non-invasive ventilator failed to support the patient. However, his vital signs, respiratory function, and circulation were aggravated.

Diagnosis: Aspiration pneumonia (inhalation of nitric acid fumes), acute respiratory distress syndrome, and hypertension.

Interventions: Veno-venous ECMO (VV-ECMO) was started 6 hours after exposure at the intensive care unit. During VV-ECMO, hypoxia improved. However, chest radiography revealed aggravated pulmonary edema. Prone positioning under ultrasound monitoring and high-dose methylprednisolone were administered on the first day. Nebulization and fiberoptic bronchoscopy for airway management were performed on the second day after the exposure. Pulmonary secretions were significantly reduced 48 hours later.

Outcomes: The patient was weaned off V-V ECMO after 6 days, achieved the standard of extubation after 9 days, and was discharged without serious pulmonary or infectious complications after 12 days of hospitalization. Three weeks after discharge, the patient's lung function showed a slight decline in the diffusion function. Two months after discharge, the patient's lung function returned to normal.

Lesson: Early ECMO combined with prone positioning and visualized management through ultrasonography can better improve the prognoses of patients and promote lung function recovery.

Figure 1.

Typical image features at 4 hours after exposure time. Pulmonary edema could be observed on the computed tomography (CT) scan. Thoracic CT disclosed bilateral peribronchovascular ground glass opacity, as well as diffuse interstitial infiltrating shadow.

Figure 2.

The chest X-rays at different times. (A) The X-ray on Day 1 after exposure showed the diffuse infiltration throughout all lung fields. (B) The X-ray on Day 5 after exposure showed that the diffuse plaques and infiltration in all lung fields were reduced obviously, and the costophrenic angle in the left region became blunt (red arrow).