LONG-TERM MEASUREMENT OF LIVER MICROCIRCULATION IN DOGS AND HUMANS

Background: We verified the possibility of using laser Doppler fluxmet ry for prolonged monitoring of hepatic perfusion; we confirm the abili ty of an implantable laser Doppler microprobe to be in constant 'optic al contact' with the liver and thus to transmit a stable microcirculat ory signal for a prolonged period of time, and we correlate the respon se of liver microcirculation to the hepatic artery blood flow reductio n in order to estimate this flow by continuous monitoring of microcirc ulation. Method: Hepatic microcirculation was recorded by a single-fib er microprobe implanted in the livers of 8 dogs and of 5 surgical ICU patients. In another 7 dogs, liver microcirculation as well as hepatic artery blood flow were recorded digitally, while an occluder was used to decrease hepatic artery flow. Results: Analysis of the initial dat a of microcirculation revealed a nonsignificant variation between cons ecutive time segments, a finding confirming the hypothesis that laser Doppler gives a very stable signal over a long period of time. Polynom ial regression analysis, performed on data pairs obtained from microci rculation and hepatic artery blood flow revealed a regression coeffici ent y = -54.22 + 1.07x + 0.0046x(2) (y = hepatic artery blood flow, x = liver microcirculation). Conclusion: This finding means that it is p ossible to watch the hepatic artery flow values continuously by the us e of this equation and simple monitoring of liver microcirculation. Th us, the use of laser Doppler fluxmetry with implantable microprobes se ems promising as a novel method for continuous assessment of hepatic a rtery blood flow.