Oxygen Saturation Targets in Pulmonary Fibrosis and Chronic Respiratory Failure

Objectives of Oxygen Saturation

For patients with pulmonary fibrosis and other conditions that present a risk of hypercapnic respiratory failure, the British Thoracic Society recommends a target oxygen saturation range of 88-92% while awaiting arterial blood gas results 1, 3
Patients with chronic respiratory failure should be carefully monitored, as hypercapnic respiratory failure with respiratory acidosis can develop during hospitalization even if initial arterial blood gases were satisfactory 2

Arterial blood gas measurement should be performed on hospital admission in patients with suspected hypercapnic respiratory failure 1, 2
Arterial blood gases should be repeated after 30-60 minutes (or if there is evidence of clinical deterioration) for all patients at risk of hypercapnic respiratory failure, even if the initial PCO2 measurement was normal 4, 3

If the pH and PCO2 are normal, the target oxygen saturation should be maintained at 94-98% unless there is a history of previous hypercapnic respiratory failure or if the patient's habitual saturation when clinically stable is below 94% (in these cases, maintain 88-92%) 2, 3
If the PCO2 is elevated but the pH is ≥7.35 and/or there is a high bicarbonate level (>28 mmol/L), the patient likely has chronic hypercapnia, and the target oxygen saturation range should be 88-92% 4, 3

For most patients at risk of hypercapnic respiratory failure, oxygen therapy should be initiated with a Venturi mask at 24% to 2-3 L/min, or a Venturi mask at 28% to 4 L/min, or nasal cannulas at 1-2 L/min 2, 3
Patients with a respiratory rate >30 breaths/min should have a flow from Venturi masks higher than the minimum specified to compensate for the increased inspiratory flow 2
Excessive oxygen use should be avoided in patients at risk of hypercapnic respiratory failure, as the risk of respiratory acidosis increases if the PaO2 is above 10.0 kPa due to previous excessive oxygen use 2

For patients using long-term home oxygen therapy (LTOT) for severe lung disease, a senior physician should consider establishing a specific target range for the patient 4, 3
Oxygen therapy should never be abruptly discontinued in hypercapnic patients, as this can cause potentially fatal rebound hypoxemia 4, 3