We have noted the update of this German S3 guideline with interest (1). We welcome the update of the limit values for initiating oxygen (O2) therapy at pulse oximetry oxygen saturation (SpO2) levels of < 92% and < 88%, respectively. To our regret, no upper limit of the SpO2 level is included in the recommendations. The S3 guideline on oxygen therapy in acute medicine (2), published in 6/2021, takes an evidence-based position on O2 therapy in COVID-19, yet unfortunately it seems not to have been considered in the guideline search. The lack of benefit from hyperoxemia (i.e. SpO2 > 96%) as a goal of oxygen therapy has been demonstrated by numerous randomized controlled studies and meta-analyses. SpO2 values of > 96% on O2 therapy should be avoided in patients with COVID-19 too. It has been shown that, when an upper SpO2 limit of 96% is used, 37% of patients breathed room air in the intensive care unit, as compared to 9% of patients without this upper SpO2 limit (3). We consider this to be relevant in the context of scarce resources during the pandemic.
In patients with respiratory failure, hyperoxemia under O2 therapy can lead to a delay in the recognition of a clinical deterioration (4).
We also recommend extending the SpO2 lower limit under O2 therapy of 88% to other patient groups at risk of hypercapnia, in addition to patients with chronic obstructive pulmonary diseases.
Beside this, it remains unclear to the reader, based on Figure 1 and the text, how the treatment should proceed in the presence of either hypoxemia without tachypnea (respiratory rate over 30/min) or tachypnea without hypoxemia (SpO2 < 92% or < 88%, respectively).
Footnotes
Conflict of interest statement:
Prof. Gottlieb is coordinator of the S3 Guideline
Sauerstoff in der Akuttherapie beim Erwachsenen (Oxygen for Acute Therapy of Adults).
Prof. Worth is chairman of the pneumology section of the German Society for Internal Medicine (Deutschen Gesellschaft für Innere Medizin).
The remaining authors declare that no conflict of interest exists.
References
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