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Cerebral blood flow and intracranial pressure during experimental subarachnoid haemorrhage
T Brinker1, V Seifert, H Dietz
1Neurosurgical Department, Medical School Hannover, Federal Republic of Germany.
Insights
In experimental subarachnoid hemorrhage, the Cushing response paradoxically increased intracranial pressure (ICP) and worsened cerebral blood flow (CBF). This suggests the Cushing response is detrimental during subarachnoid hemorrhage.
Area of Science:
- Neuroscience
- Physiology
- Neurosurgery
Background:
- Subarachnoid hemorrhage (SAH) is a critical condition characterized by elevated intracranial pressure (ICP).
- The Cushing response, a physiological reaction to increased ICP, aims to maintain cerebral blood flow (CBF).
Purpose of the Study:
- To investigate the interplay between ICP, systemic blood pressure (SBP), and CBF during experimental SAH in cats.
- To evaluate the role and effect of the Cushing response in SAH.
Main Methods:
- Continuous monitoring of regional cerebral blood flow (rCBF) using a thermal diffusion method with a Peltier stack.
- Induction of experimental subarachnoid hemorrhage in feline models.
- Measurement of ICP and SBP throughout the experiment.
Main Results:
- SAH induced a rapid and significant rise in ICP, from baseline to 176.1 +/- 27.8 mmHg.
- The elevated ICP led to a temporary cessation of cerebral circulation.
- The Cushing response exacerbated ICP, failing to improve CBF during the hemorrhage phase.
Conclusions:
- The Cushing response during SAH acts as a deleterious mechanism, further increasing ICP.
- This response does not benefit, but rather impairs, cerebral circulation during subarachnoid hemorrhage.
- Findings challenge the traditional view of the Cushing response as a protective reflex in SAH.
Abstract:
The relationships of intracranial pressure (ICP), systemic blood pressure (SBP) and cerebral blood flow (CBF) during experimental subarachnoid haemorrhage were investigated in cats. Continuous monitoring of regional cerebral blood flow (rCBF) was done by a thermal diffusion method using a Peltier stack. During haemorrhage ICP rose within 5.4 +/- 0.97 minutes from 10.5 +/- 4.9 to 176.1 +/- 27.8 mmHg. This strong increase of ICP resulted in a temporary arrest of cerebral circulation. The Cushing response during the haemorrhage could not improve the cerebral circulation, but in contrast caused a further increase of ICP. After the haemorrhage the cerebral blood flow normalised within minutes. It is concluded, that the Cushing response during a subarachnoid haemorrhage should be regarded as a deleterious rather than a beneficial mechanism.