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Abstract #6702 Published in IGR 4-1
Effect of isovolumic hemodilution on oxygen delivery to the optic nerve head
Chamot SR; Petrig BL; Pournaras CJ; Riva CEKlinische Monatsblätter für Augenheilkunde 2002; 219: 292-295
BACKGROUND: To investigate the effect of isovolumic hemodilution on the tissue oxygenation of the optic nerve head (ONH). MATERIAL AND METHODS: In nine miniature pigs (6-12 kg), hemodilution was performed by replacing 100-140 ml of blood by an equivalent volume of 6% hydroxyethyl starch in saline. The blood flow parameters in the ONH microcirculation, namely velocity (BVel), volume (BVol) and flow (BF), were measured by laser Doppler flowmetry. Microelectrodes placed at approximately 50 μm from the disc surface and the phosphorescence quenching technique were used to measure pO 2 in the vitreous (pO 2vitro) and in the ONH capillary blood (pO 2blood), respectively. Arterial blood pressure, hematocrit (Hct) and gas content were documented. RESULTS: In all animals, hemodilution reduced Hct by 30 ± 6%. All the flow parameters increased markedly. Simultaneously, pO 2blood (baseline: 31 ± 3 mmHg) dropped to approximately 75% of its initial value, while pO 2vitr (baseline: 26 ± 8 mmHg) increased by 15 ± 8%. CONCLUSIONS: Hemodilution leads to an increase of pO 2vitr reflecting a similar rise of the ONH tissue pO2. This effect results from an enhanced blood perfusion of the ONH, which over-compensates the decrease of the blood O2 content.
Dr. S.R. Chamot, Laboratoire d'Optique et de Biophysique, Institut de Recherche en Ophtalmologie, Sion, Switzerland
Classification:
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
