Laser Doppler velocimetry in critically ill patients.

Cutaneous blood flow may be an indirect measure of circulatory function estimated by continuous, noninvasive laser Doppler velocimetry (LDV). It has been postulated that LDV may be a useful monitor of cardiac output changes. To test this hypothesis, LDV was evaluated in 67 critically ill adult patients with simultaneous measurements of cardiac index (CI) and other physiologic variables. Heated and unheated laser probes were utilized. The results indicate that LDV reflects acute directional changes of CI. Further, with the heated laser probe, the magnitude of acute CI change is reflected. However, there are gradual changes over time of LDV which may occur independently of CI or other monitored variables. Hence, absolute LDV values are not predictive of absolute CI values.