Introduction
Materials and methods
Patient selection and profile
Continuous monitoring and sampling of multimodal physiological data
Routine treatment
Data analysis
Results
Patient characteristics
PtiO2-CPP relationship
Variable | Minimum | Maximum | Mean | Standard deviation |
---|---|---|---|---|
Mean arterial blood pressure (mmHg) | 62 | 139 | 96 | 11 |
Intracranial pressure (mmHg) | 0 | 69 | 15 | 10 |
Cerebral perfusion pressure (mmHg) | 27 | 128 | 81 | 14 |
End tidal carbon dioxide (mmHg) | 25 | 64 | 32 | 4 |
Peripheral saturation of oxygen (%) | 78 | 100 | 99 | 2 |
Temperature (°C) | 31 | 39 | 36.7 | 0.9 |
Hemoglobin (g/dl) | 6.7 | 14 | 10.2 | 1.4 |
Hours monitored per patient | 27 | 195 | 40 | 36 |
CPP < 50 mmHg | CPP < 60 mmHg | CPP < 70 mmHg | CPP < 80 mmHg | CPP < 90 mmHg | CPP < 100 mmHg | CPP < 130 mmHg | ||
---|---|---|---|---|---|---|---|---|
PtiO2 | Spearman's Rho coefficienta | 0.54 | 0.50 | 0.19 | 0.24 | 0.24 | 0.24 | 0.29 |
Probability | < 0.05 | < 0.01 | < 0.01 | < 0.01 | < 0.01 | < 0.01 | < 0.01 | |
N samples | 16 | 75 | 308 | 776 | 1,252 | 1,510 | 1,672 |
CPP thresholds for hypoxia
PtiO2 percentiles (mmHg) | |||||||
---|---|---|---|---|---|---|---|
5 | 10 | 25 | 50 | 75 | 90 | 95 | |
CPP < 60 mmHg | 0 | 4 | 8 | 15a | 22 | 35 | 42 |
CPP 60–70 mmHg | 8 | 10 | 15a | 19 | 30 | 48 | 51 |
CPP > 70 mmHg | 12 | 15a | 20 | 27 | 33 | 41 | 48 |
Discussion
The effect of CPP on PtiO2
Limitations of the study
Conclusion
Key messages
-
In severe TBI, the risk of brain tissue hypoxia is common when CPP is below 60 mmHg, less frequent when it is between 60 and 70 mmHg, and lower above these CPP thresholds.
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Brain hypoxia occurs less frequently at higher CPP
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In the case of proven brain hypoxia and once treatable non-ischemic causes have been stabilized, maintaining higher CPP may be helpful.