LASER-DOPPLER FLOWMETRY FOR ESTIMATION OF BONE BLOOD-FLOW - STUDIES OF REPRODUCIBILITY AND CORRELATION WITH MICROSPHERE TECHNIQUE

The blood flow in the femoral condyles of six pigs was measured by the microsphere technique and by laser Doppler flowmetry (LDF) before and after clamping of the external iliac artery. A significant decrease i n the bone blood flow was found with both microsphere and LDF measurem ents, and a high correlation was found between the two methods. After release of the arterial clamp, the LDF values rapidly returned to appr oximately the same values as before clamping. In a second part of the study, the LDF output signal was studied in the intertrochanteric area of eight patients. The reproducibility of two LDF measurements at the same location was within 15%. The temporal variability of the LDF sig nal during 10 min of recording showed only slight variations. It is co ncluded that LDF is relative in nature and that the mean LDF output si gnal is suitable for monitoring dynamic responses of the bone blood fl ow to various stimuli. Several consecutive measurements have to be per formed if the blood flow at different locations of a specific bone are to be compared with each other.