The following is a summary of ” Oxygen reactivity index indicates disturbed local perfusion regulation after aneurysmal subarachnoid hemorrhage: an observational cohort study” published in the June 2023 issue of Critical Care by Kastenholz et al.
Delayed cerebral ischemia (DCI) patients may experience impaired cerebral autoregulation (CA), with hypoperfused territories potentially worsening CA estimation, potentially affecting Oxygen Reactivity Index (ORx) and the pressure reactivity index (PRx).
Researchers performed a retrospective study where ORx and PRx were compared in 76 patients with aneurysmal subarachnoid hemorrhage (aSAH) with DCI diagnosis. Intracranial pressure (ICP) perfusion pressure and brain tissue oxygenation (PbtO2) probes were stratified into three groups: DCI+/probe, DCI+/probe−, and DCI−.
The results showed no correlation between the PRx and ORx (r =− 0.01, P=0.56). The mean of ORx was higher with a hypoperfused probe (ORx DCI +/probe +0.28 ± 0.13 vs. DCI + /probe− 0.18 ± 0.15, P< 0.05). PRx detected poorer autoregulation with higher (ICP0 (days 1–3) but not when ICP was lower. ORx was higher in the DCI + /probe + group from day three onward. ORx and PRx were similar between DCI and non-DCI groups (ORx DCI + /probe− 0.18 ± 0.15 vs. DCI− 0.20 ± 0.14; P=0.50; PRx DCI + /probe− 0.06 ± 0.20 vs. DCI− 0.08 ± 0.17, P= 0.35).
They concluded that homeostatic mechanisms differ between PRx and ORx; neither are interchangeable measures; further research needed for robustness in autoregulation-targeted treatment.
Source: ccforum.biomedcentral.com/articles/10.1186/s13054-023-04452-3