JOURNAL CLUB - Oxygen Targets
By: Marcelo Alcantara, Médico - 07/25/2022 09:45
Another paper from the excellent series: Lasting Legacy In Intensive Care Medicine.
Paul J. Young, Carol L. Hodgson & Bodil S. Rasmussen published a review of therapeutic goals or targets for PaO2 in different settings.
The first two are from Oceania, New Zealand, and Australia, and the third is from Germany.
The figure below presents a summary of the authors' recommendations.
They built it based on the most recent evidence from studies that compared strategies based on predefined oxygen therapy targets, generally comparing more liberal or conservative approaches.
The authors highlight the limitations of observational studies on the topic. As a confounding factor, they point out that more severe patients with poor tissue and peripheral perfusion may eventually receive a higher or more liberal titration of FIO2 and therefore present higher PaO2.
Thus, the association of higher PaO2 with lower survival may not reflect a cause-and-effect association but rather be a marker of severity.
The authors cite the best RCTs, namely: the ICU-ROX (n 1000), the RCT LOCO2 (n 205), the HOT-ICU (n 2000), and the Dutch RCT (n 400). Unfortunately, these studies did not demonstrate significant differences between more liberal or conservative strategies regarding outcomes such as mortality.
However, sample heterogeneity can be a confounding factor, and it is impossible to exclude clinically meaningful effects in specific subgroups of patients.
Post-hoc analyzes of the ICU-ROX suggest that lower oxygenation targets may be favorable in cases of post-ischemic encephalopathy.
At the same time, higher levels may be preferable in other causes of brain injury or sepsis.
Another post-hoc analysis of the HOT-ICU trial raised the possibility that higher oxygenation targets may benefit patients with septic shock.
It is worth noting that, as a general rule, SpO2 close to 100% should be generally avoided.
Below, check two arterial blood gas analyses obtained with the Xlung simulator for the same PaO2 of 100mmHg in two scenarios, the one on the left with normal pH at 37oC and the one on the right with acidemia and fever (39oC).
For the same PaO2 of 100mmHg, two SpO2 were obtained, 97% and 94%, respectively!
They illustrate the importance of complementing the information obtained by pulse oximetry with arterial blood gas analysis, especially in conditions where the accuracy of the former may be compromised, such as in cases of shock.
Finally, the authors cite at least 5 RCTs underway that should shed light on the question that remains open about the ideal targets for oxygen therapy.
Here is a link to the article:
Young, P.J., Hodgson, C.L. & Rasmussen, B.S. Oxygen targets. Intensive Care Med 48, 732–735 (2022). https://doi.org/10.1007/s00134-022-06714-0
What is your current practice on this topic?
Which PaO2 and SpO2 targets have you been using?
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