Introduction: Glucose is the main metabolic substrate and its extraction depends on brain metabolism. The influence of venous hypertension resulting form altered internal jugular vein valve function on brain metabolism has been described [1,2]. The aim of the study was to analyse relationships between brain glucose extraction (a-v) Gluc, gradient of lactate concentrations (a-v) Lact and pressure gradient across the internal jugular valve (JP-CVP) during CABG.
Method: 15 patients, aged 47-72 underwent CABG. The (a-v) Gluc, (a-v) Lact, JP-CVP were noted at the following 11 stages: 1. induction of anaesthesia - initial values, 2. surgery before ECC, 3. ECC commencement, 4. aorta cross clamping, 5. aorta declamping, 6. end of ECC, 7. end of surgery, 8. the evening after surgery, 9. the morning of the first postoperative day, 10. the evening of the first postoperative day and 11. the morning of the second postoperative day. Pressure in the jugular vein was measured in the jugular bulb. CVP was obtained by cannulation of the opposite jugular vein. The Wilcoxon test was used for statistical analysis.
Results: In comparison with initial values, significant increases of JP-CVP gradient were observed in stages 4, 5, 8, 9, 10 and 11. These changes were accompanied in all but stage 10 by elevated (a-v) Gluc extraction. Initial increase of (a-v) Gluc in stages 4 and 5 was followed by elevated (a-v) Lact recorded in stages 5, 6 and 7.
Discussion: Obstructed outflow of the brain circulation is one of the deleterious factors affecting brain metabolism. Sum-Ping's study  emphasises the relationship between brain pathology and jugular valve insufficiency. Our study shows that the changes of JP-CVP and (a-v) Gluc occur simultaneously and, at least with intra-operative measurements, can reflect brain metabolism pathology.
1 Imai M, Hanaoka Y, Kemmotsu O. Valve injury: a new complication of internal jugular vein cannulation. Anesth Analg
2 Sum-Ping ST. Internal jugular valves: competent or incompetent? Anesth Analg