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Spinal cord blood flow changes following systemic hypothermia and spinal cord compression injury: an experimental
H Westergren1, M Farooque, Y Olsson
1Unit of Neurosurgery, Department of Neuroscience, Uppsala University, Sweden.
Study Design:
It is well known that changes of the body temperature as well as trauma influence the blood flow in the brain and spinal cord. However, there is still a lack of knowledge concerning the levels of blood flow changes, especially during hypothermia.
Objectives:
This investigation was carried out to examine the effects of systemic hypothermia and trauma on spinal cord blood flow (SCBF).
Methods:
Twenty-four rats were randomized either to thoracic laminectomy only (Th VII-IX) or to 35 g spinal cord compression trauma. The animals were further randomized to either constant normothermia (38 degrees C) or to a systemic cooling procedure, ie reduction of the esophageal temperature from 38 to 30 degrees C. SCBF was recorded 5 mm caudal to the injury zone using Laser-Doppler flowmetry which allows a non-invasive continuous recording of local changes in the blood flow. The autoregulation ability was tested at the end of the experiments by inducing a 30-50 mmHg blood-pressure fall, using blood-withdrawal from the carotid artery.
Results:
The mean SCBF decreased 2.8% and 3.5% per centigrade reduction of esophageal temperature in the animals sustained to hypothermia with and without trauma, respectively. This could be compared to a decrease of 0.2%/min when only trauma was applied. No significant differences were seen between the groups concerning auto regulatory ability.
Conclusions:
Our results indicate that the core temperature has a high impact on the SCBF independent of previous trauma recorded by Laser-Doppler flowmetry. This influence exceeds the response mediated by moderate compression trauma alone.