Optimal Oxygenation, Hyperoxaemia, and Hypoxaemia in Patients With ARDS

blood oxygenator
blood oxygenator
What happens when ventilated patients with ARDS receive too much or too little oxygen—and what PaO2 level is optimal?

Research to determine a reasonable oxygenation target for ventilated patients with acute respiratory distress syndrome (ARDS) found that partial pressure of arterial oxygen (PaO2) levels were linked to mortality when they were either above or below a certain threshold. Results of this investigation were recently published in BMC Pulmonary Medicine.

The researchers examined whether there was a relationship between average time-weighted PaO2 and intensive care unit (ICU) mortality in patients with ARDS. Investigators also evaluated whether oxygenation targets were associated with changes in hospital mortality or duration of invasive mechanical ventilation.

The prospected study measured oxygen exposure variables at 6-hourly intervals in 202 patients with ARDS. The primary exposure marker was average time-weighted PaO2 calculated over a maximum of 7 days from meeting ARDS criteria. The primary outcome was ICU mortality.

Among patients included in the analysis, the overall ICU mortality was 31%. When outcomes were examined, the average time-weighted PaO2 during the first 7 days of ARDS was similar between nonsurvivors and survivors. However, in univariable and multivariable analysis, average time-weighted PaO2 demonstrated a U-shaped relationship with both ICU mortality and in-hospital mortality: for average time-weighted PaO2 values less than 13.5 kPa, increased mortality is associated with decreasing PaO2; for values greater than 13.5 kPa, increased mortality is associated with increasing PaO2.

The study authors wrote, “In patients with ARDS, the predicted probability of both ICU and hospital mortality was lowest when the average time-weighted PaO2 was between 12.5 and 14 kPa (93.8–105.0 mmHg), suggesting this is a reasonable oxygenation target for clinicians to aim for.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Boyle AJ, Holmes DN, Hackett J, et al. Hyperoxaemia and hypoxaemia are associated with harm in patients with ARDS. BMC Pulm Med. 2021;21(1):285. doi:10.1186/s12890-021-01648-7