A Study of the Effects of Using Different Cerebral Perfusion Pressure (CPP) Thresholds to Quantify CPP “Secondary Insults” in Children

Abstract

Little is known about the incidence of secondary insults, particularly cerebral perfusion pressure insults, in children. The objectives of this study were to assess the duration of CPP insults at three different thresholds in children and to relate CPP insults to outcome.

Eighteen children (age < 16, median & mean 8 years) admitted to the Neurointensive Care Unit who had ICP, MAP and CPP continuously monitored were studied. Using the Edinburgh secondary insult analysis program, data was scanned for CPP insults at three different thresholds: CPP < 70 mmHg, <60 mmHg and <50 mmHg. Outcome was assessed using the Glasgow Outcome Scale.

Thirty percent of the time CPP was between 60 and 70 mmHg, 21% of the time CPP was between 50 and 60 mmHg and 8% of the time the CPP was less than 50 mmHg. Compared with adults, there was more than twice the incidence of CPP insults in all threshold groups.

BP remained relatively stable above 70 mmHg across all three CPP threshold groups. However, ICP increased slightly on average from about 13 → 17 mmHg when CPP decreased from the <70 to < 60 mmHg group (p < 0.001). There was a marked increase in ICP to greater than 30 mmHg on average in the CPP < 50 mmHg group (p < 0.001).

CPP insults less than 70, 60 and 50 mmHg do occur commonly in children, a larger dataset and possibly longer term follow up mea- sures will be needed to identify potentially treatable physiological factors most effecting the outcome of children.