Successful Asymmetric Nasal High-Flow Therapy in CO₂ Narcosis Triggered by Pneumonia in an Elderly Patient: A Case Report.

The number of elderly people transported to the emergency department with respiratory failure is increasing. Some do not wish to receive invasive interventions, but when patients are unconscious, determining their treatment preferences can be challenging. Asymmetric nasal high-flow (NHF) therapy is a non-invasive respiratory support method that has shown effectiveness in type II respiratory failure, although there are no prior reports on its use for carbon dioxide (CO₂) narcosis. We report a case in which asymmetric NHF therapy was effective for CO₂ narcosis triggered by pneumonia in an elderly patient. A 96-year-old man with impaired consciousness was brought to the emergency department. Arterial blood gas analysis revealed respiratory acidosis, and imaging confirmed the presence of pneumonia and CO₂ narcosis secondary to pneumonia. Given the patient's advanced age, the goal was to avoid invasive intubation. Non-invasive ventilation (NIV) was considered, but deemed unsuitable because of excessive sputum and impaired consciousness. Therefore, asymmetric NHF therapy was initiated. The patient became responsive within 40 minutes, and his respiratory acidosis improved. After regaining consciousness, the treatment plan was discussed with the patient, and antibiotic therapy and asymmetric NHF were continued. For elderly patients, patient preference should be taken into account when making airway management decisions. Although NIV is commonly used for CO₂ narcosis, it is not suitable for certain patients, such as patients with excessive sputum and impaired consciousness. Asymmetric NHF is a noninvasive option that may help reduce the partial pressure of arterial CO