Effect of cerebral perfusion pressure on contusion volume following impactinjury

Object. Although it is generally acknowledged that a sufficient cerebral pe rfusion pressure (CPP) is necessary for treatment of severe head injury, th e optimum CPP is still a subject of debate. The purpose of this study was t o investigate the effect of various levels of blood pressure and, thereby, CPP on posttraumatic contusion volume. Methods. The left hemispheres of 60 rats were subjected to controlled corti cal impact injury (CCII). In one group of animals the mean arterial blood p ressure (MABP) was lowered for 30 minutes to 80, 70, 60, 50, or 40 mm Hg 4 hours after contusion by using hypobaric hypotension. In another group of a nimals the MABP was elevated for 3 hours to 120 or 140 mm Hg 4 hours after contusion by administering dopamine. The MABP was not changed in respective control groups. Intracranial pressure (ICP) was monitored with an ICP micr osensor. The rats were killed 28 hours after trauma occurred and contusion volume was assessed using hematoxylin and eosin-stained coronal slices. No significant change in contusion volume was caused by a decrease in MABP fro m 94 to 80 mm Hg (ICP 12 +/- 1 mm Hg), but a reduction of MABP to 70 mm Hg (ICP 9 +/- 1 mm Hg) significantly increased the contusion volume (p < 0.05) . A further reduction of MABP led to an even more enlarged contusion volume . Although an elevation of MABP to 120 mm Hg (ICP 16 +/- 2 mm Hg) did not s ignificantly affect contusion volume, there was a significant increase in t he contusion volume at 140 mm Hg MABP (p < 0.05; ICP 18 +/- 1 mm HE) Conclusions. Under these experimental conditions, CPP should be kept within 70 to 105 mm Hg to minimize post traumatic contusion volume. A CPP of 60 m m HE and lower as well as a CPP of 120 mm HE and higher should be considere d detrimental.