INFLUENCE OF BODY POSITION ON TISSUE-PO(2), CEREBRAL PERFUSION-PRESSURE AND INTRACRANIAL-PRESSURE IN PATIENTS WITH ACUTE BRAIN INJURY

It is a common practice to position head injured patients in bed with the head elevated above the level of the heart in order to reduce intr acranial pressure (ICP). This practice has been in vivid discussion si nce some authors argue a horizontal body position will increase the ce rebral perfusion pressure (CPP) and therefore improve cerebral blood f low (CBF). However, ICP is generally significantly higher in the horiz ontal position. The aim of this study was to evaluate changes in regio nal microcirculation using tissue pO(2) (ti-pO(2)), as well as changes in cerebral perfusion pressure (CPP) and intracranial pressure induce d by changes in body position in patients with head injury. The effect of 0 degrees and 30 degrees head elevation on ti-pO(2), CPP, ICP and arterial blood pressure (MABP) was studied in 22 head injured patients during day 0-72 after trauma. The mean ICP was significantly lower at 30 degrees head elevation than at 0 degrees (14.1 + 8.6 vs. 19.9 + 8. 3 mmHg). While MABP was unaffected by head elevation, CPP was slightly higher at 30 degrees than at 0 degrees 176.5 + 13.5 vs. 71.5 + 13.2 m mHg). However, regional ti-pO(2) was unaffected by body position (30 d egrees vs. 0 degrees: 24.9 + 13.1 vs. 24.7 + 12.9 mmHg). In addition, there was no change in the time course after trauma concerning these f indings in the individual patients. The data indicate that a moderate head elevation of 30 degrees reduces ICP without jeopardizing regional cerebral microcirculation as monitored using a polarographic ti-pO(2) microcatheter.