Aim. The aim of this study was to evaluate the arterio-venous difference in carbon dioxide tension (DPCO2) and the ratio between DPCO2 and arterio-jugular oxygen difference (AJDO2) as indicators of compensated or uncompensated cerebral hypoperfusion. Methods. Cerebral blood flow (CBF) was reduced stepwise in 6 pigs by inducing intracranial hypertension with consequently cerebral perfusion pressure (CPP) reduction: CBF 100%, 50-60 % of baseline, 20-30% of baseline. Intracranial pressure (ICP), mean arterial pressure (MAP), CPP and CBF (laser-Doppler method) were continuously recorded. Superior sagittal sinus was punctured for the determination of AJDO2 and DPCO2. Results. CBF impairment was accompanied by changes in AJDO2 from 6.03 +1.21 vol% to 7.32±1.30 vol%, up to 8.07±1.32 vol% (P2 from 12.17±3.25 mmHg to 16±4.12 mmHg, up to 26.5±6.41 mmHg (P2/AJDO2 ratio from 2.05±0.39 to 2.06±0.72 up to 3.41±1.09 in the 3 phases (P2 increase s, indicating greater extraction of O2 to satisfy aerobic metabolism. However, this mechanism can no longer compensate once a critical CBF threshold is reached. DPCO2 rises slowly during moderate CBF reduction because of defective washout; the rise is steeper during marked CBF impairment when anaerobic metabolism takes place. During cerebral hypoperfusion the venous blood gases and acid base variables mirror the degree of cerebral perfusion. In particular the DPCO2, and the DPCO2/AJDO2 ratio may be useful markers of critical brain hypoperfusion.
|Number of pages||7|
|Publication status||Published - Jun 2006|
- Arterio-venous difference
- Cerebral hypoperfusion
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine