TY - JOUR
T1 - Brain tissue oxygen tension response to induced hyperoxia reduced in hypoperfused brain
AU - Hlatky, Roman
AU - Valadka, Alex B.
AU - Gopinath, Shankar P.
AU - Robertson, Claudia S.
PY - 2008/1
Y1 - 2008/1
N2 - Object. Increasing PaO2 can increase brain tissue PO2 (PbtO2). Nevertheless, the small increase in arterial O2 content induced by hyperoxia does not increase O2 delivery much, especially when cerebral blood flow (CBF) is low, and the effectiveness of hyperoxia as a therapeutic intervention remains controversial. The purpose of this study was to examine the role of regional (r)CBF at the site of the PO 2 probe in determining the response of PbtO2 to induced hyperoxia. Methods. The authors measured PaO2 and PbtO2 at baseline normoxic conditions and after increasing inspired O2 concentration to 100% on 111 occasions in 83 patients with severe traumatic brain injury in whom a stable xenon-enhanced computed tomography measurement of CBF was available. The O2 reactivity was calculated as the change in PbtO2 X 100/change in PaO2. Results. The O2 reactivity was significantly different (p <0.001) at the 5 levels of rCBF (<10, 11-15, 16-20, 21-40, and > 40 ml/100 g/min). When rCBF was < 20 ml/100 g/min, the increase in PbtO2 induced by hyperoxia was very small compared with the increase that occurred when rCBF was > 20 ml/100 g/min. Conclusions. Although the level of CBF is probably only one of the factors that determines the PbtO2 response to hyperoxia, it is apparent from these results that the areas of the brain that would most likely benefit from improved oxygenation are the areas that are the least likely to have increased PbtO2.
AB - Object. Increasing PaO2 can increase brain tissue PO2 (PbtO2). Nevertheless, the small increase in arterial O2 content induced by hyperoxia does not increase O2 delivery much, especially when cerebral blood flow (CBF) is low, and the effectiveness of hyperoxia as a therapeutic intervention remains controversial. The purpose of this study was to examine the role of regional (r)CBF at the site of the PO 2 probe in determining the response of PbtO2 to induced hyperoxia. Methods. The authors measured PaO2 and PbtO2 at baseline normoxic conditions and after increasing inspired O2 concentration to 100% on 111 occasions in 83 patients with severe traumatic brain injury in whom a stable xenon-enhanced computed tomography measurement of CBF was available. The O2 reactivity was calculated as the change in PbtO2 X 100/change in PaO2. Results. The O2 reactivity was significantly different (p <0.001) at the 5 levels of rCBF (<10, 11-15, 16-20, 21-40, and > 40 ml/100 g/min). When rCBF was < 20 ml/100 g/min, the increase in PbtO2 induced by hyperoxia was very small compared with the increase that occurred when rCBF was > 20 ml/100 g/min. Conclusions. Although the level of CBF is probably only one of the factors that determines the PbtO2 response to hyperoxia, it is apparent from these results that the areas of the brain that would most likely benefit from improved oxygenation are the areas that are the least likely to have increased PbtO2.
KW - Brain tissue oxygenation
KW - Brain trauma
KW - Cerebral blood flow
KW - Hyperoxia
UR - http://www.scopus.com/inward/record.url?scp=38149113378&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=38149113378&partnerID=8YFLogxK
U2 - 10.3171/JNS/2008/108/01/0053
DO - 10.3171/JNS/2008/108/01/0053
M3 - Article
C2 - 18173310
AN - SCOPUS:38149113378
SN - 0022-3085
VL - 108
SP - 53
EP - 58
JO - Journal of Neurosurgery
JF - Journal of Neurosurgery
IS - 1
ER -