Neuroanesthesia & neurocritical care
The oxygen reactivity index indicates disturbed local perfusion regulation after aneurysmal subarachnoid hemorrhage: an observational cohort study
Authors' conclusion
PRx and ORx are not interchangeable measures of autoregulation, as they likely measure different homeostatic mechanisms. PRx represents the classical cerebrovascular reactivity and might be better suited to detect disturbed autoregulation during phases with moderately elevated ICP. Autoregulation may be poorer in territories affected by DCI. These local perfusion disturbances leading up to DCI may be more readily detected by ORx than PRx.
Study context
- Population
- Patients with aneurysmal SAH with or without delayed cerebral ischemia
- Participants
- 76 patients
- Exposure
- ORx vs PRx by ICP/PbtO2 probe location relative to hypoperfused area
- Outcome
- Mean ORx and PRx (indices of cerebral autoregulation), compared daily until DCI diagnosis
Methodological detailsretrospective stratification by CT perfusion
- Retrospective stratification by CT perfusion
Main finding
As reported in the abstract
Mean ORx and PRx by probe location
| Group | Value | PRx |
|---|---|---|
| Delayed cerebral ischemia (DCI) + /probe + | mean 0.28 (SD 0.13) | 0.12 ± 0.17 |
| DCI + /probe- | mean 0.18 (SD 0.15) | 0.06 ± 0.20 |
| DCI- | mean 0.20 (SD 0.14) | 0.08 ± 0.17 |
Value
Delayed cerebral ischemia (DCI) + /probe +mean 0.28 (SD 0.13)
DCI + /probe-mean 0.18 (SD 0.15)
DCI-mean 0.20 (SD 0.14)
PRx
Delayed cerebral ischemia (DCI) + /probe +0.12 ± 0.17
DCI + /probe-0.06 ± 0.20
DCI-0.08 ± 0.17
- DCI + /probe + vs DCI + /probe-: P < 0.05
- DCI + /probe + vs DCI + /probe-: P = 0.35
- DCI + /probe- vs DCI-: P = 0.50
- DCI + /probe- vs DCI-: P = 0.35
Observational data: associations, not effects.
Further findings
Correlation of PRx and ORx
- PRx and ORx not correlated (r)
- - 0.01
- p
- P = 0.56
Time course of PRx and ORx
- PRx detected poorer autoregulation in early phase with higher ICP (days 1-3) but did not differentiate the 3 groups thereafter
- ORx higher in DCI + /probe + than the other 2 groups from day 3 onward
Original publication
The oxygen reactivity index indicates disturbed local perfusion regulation after aneurysmal subarachnoid hemorrhage: an observational cohort study. Crit Care. Published 13 June 2023. doi:10.
Composed by AI from the published abstract and checked against it. How Briefs are made →