| Jugular venous oxygen saturation (SjvO2) | Brain tissue oxygen tension (PbtO2) | Cerebral oximetry using near-infrared spectrometry (SctO2 – NIRS) | |
| Basic principle -indicator | Oxygen consumption —oxygen need—cerebral metabolism | Oxygen diffusion > cerebral metabolism | Oxygen consumption—oxygen need—cerebral metabolism in normal healthy brain |
| Applicability | Continuous at bedside | Continuous at bedside | Continuous at bedside |
| Application fields | Intraoperative ICU | Intraoperative ICU | Intraoperative ICU |
| Device | Invasive | Minimally invasive | Non-invasive (main advantage) |
| Limitations of use | -Catheter tip displacement -Compiled hemispheric measurement -Lack of detection of limited ischaemia -Extracranial blood pollution | -Local or regional measurement -Site-dependent measurement | -Mainly healthy brain monitoring -Inter- & intra-individual variability -Complex multi-factor brain pathophysiological process -Compiled hemispheric measurement -Desaturation ≠ real ischaemia and infarction -Specific SctO2 determination methodology of each device |
| Cost-investment | -Monitoring -Probe (reusable or single use) | -Monitoring -Probe (single use) | -Monitoring -Probe (single use) |
| Technical expertise, management & nursing | Advanced Time-consuming | Advanced Time-consuming | Basic (intuitive) |
| Specific infrastructure for insertion | Special need (invasive, ICU, or OR) | Special need (minimally invasive, OR) | No need |
| Ischaemia detection | Hemispheric (focal ischaemia undetected) | Local (insertion site-dependent) | Hemispheric |
| CPP correlation | CPP < 60 mmHg: PbtO2↓ CPP > 60 mmHg: PbtO2 ≈ or ↑ | Variable (+/− more specific than SjvO2) | |
| Numeric values | -Normal: 60% - 90% -Critical: 50% - 55% during 15 min = cerebral ischaemia | -Normal: 25 - 35 mmHg -Critical: <15 mmHg = ischaemia -<6 mmHg = infarction, even cerebral death | -Normal: 60% - 75% -Baseline variation: 10% -↓13%: ischaemic threshold -35% during 2 - 3 h: infarction |
| Thresholds correspondance | 50% | 8.5 mmHg | To be determined-variable (correct for internal carotid clamping, circulatory arrest) |