High-Dose Oxygen Therapy and Acute Hypercapnia in Elderly Patients: A Case Series Analysis

BACKGROUND Detection of episodes of desaturation on pulse oximetry in elderly people in community settings is now a common occurrence. Transfer of such patients to hospital by ambulance has led to a greatly increased exposure to high-dose (FiO₂ > 50%) inhaled oxygen therapy in this group. Current British Thoracic Society (BTS) guidelines recommend administration of oxygen, 15 L/min via a non-rebreather mask (NRB) to acutely hypoxemic patients with an SpO₂ below 85% on room air. In some elderly subjects, such high-dose oxygen therapy induces significant hypercapnia in the absence of an identifiable risk factor for oxygen-induced CO₂ retention. CASE REPORT This case series describes 3 very elderly (>85 years old) female patients developing acute hypercapnia shortly after initiation of high-dose inhaled oxygen therapy. In each of these cases, hypercapnia developed in the absence of an accepted risk factor for oxygen-induced CO₂ retention. In 2 cases, CO₂ narcosis resolved within hours of the establishment of controlled oxygen therapy on bi-level positive airway pressure (BPAP). The possibility of oxygen-induced CO2 retention was not considered by the treating physicians in the acute setting. CONCLUSIONS The possibility of oxygen-induced CO₂ retention should be considered in all elderly patients developing acute type II respiratory failure in the setting of high-dose oxygen therapy. Failure to recognize oxygen-induced CO₂ retention has significant implications for patient outcome and resource utilization.