Relationship between oral tissue blood flow and oxygen tension in rabbit.

Several studies have reported tissue blood flow and tissue oxygen tension during anesthesia, whereas there are few reports that discuss the relationship between tissue blood flow and tissue oxygen tension. The goal of this study was to investigate the relationship between these two variables before and after stellate ganglion block (SGB). We utilized 8 male Japan White rabbits. Anesthesia was maintained with propofol. For SGB, 0.2 ml of 1% lidocaine was injected and changes in mandibular bone marrow blood flow (BBF) and mandibular bone marrow oxygen tension (PbO(2)) were observed (Group B). After the observed variables completely recovered, 0.2 ml of 1% lidocaine was again injected and changes in masseter muscle blood flow (MBF) and masseter muscle oxygen tension (PmO(2)) were observed (Group M). The observed variables were hemodynamic parameters, common carotid artery blood flow, L (left side)-BBF, R (right side)-BBF, L-PbO(2), R-PbO(2), L-MBF, R-MBF, L-PmO(2) and R-PmO(2). In both groups, positive correlations (r=0.99; y=0.68x - 3.49 in Group B and r=0.99; y=0.62x + 0.47 in Group M) were observed when tissue blood flow was set at the X-axis and tissue oxygen tension at the Y-axis. In contrast, when tissue blood flow was set at the Y-axis and tissue oxygen tension at the X-axis, two regression lines almost overlapped (y=1.47x + 5.12 in Group B and y=1.59x - 0.28 in Group M). Therefore, it is estimated that tissue blood flow increases by approximately 15 ml/min/100g when tissue oxygen tension increases by 10 mmHg. In conclusion, there is a positive correlation between tissue blood flow and tissue oxygen tension. Changes in tissue oxygen tension should reflect the increase or decrease in tissue blood flow.