HEMORRHAGE DURING ANESTHESIA AND SURGERY - CONTINUOUS MEASUREMENT OF MICROCIRCULATORY BLOOD-FLOW IN THE KIDNEY, LIVER, SKIN AND SKELETAL-MUSCLE

Multichannel laser Doppler flowmeters allow continuous, simultaneous m easurement of perfusion in several organs. We measured microcirculator y blood flow in the kidney, liver, skin and skeletal muscle in 10 anae sthetized rats subjected to abdominal surgery and graded haemorrhage ( withdrawal of 5% total blood volume every 10 min). Mean arterial blood pressure, heart rate and haemoglobin concentrations were also measure d. Muscle blood flow decreased after only 10% blood loss, but without significant changes in the other organs. At this time the perfusion si gnal from the muscle was cycling 2-3 times per min (slow wave flowmoti on) which was never seen in any other organ. After 35% blood loss, all organs monitored maintained approximately 70% of initial flow, despit e a 45% decrease in mean arterial pressure from 104+/-12 to 55+/-9 mmH g (mean+/-SD). After 40% blood loss there was a sharp decrease in bloo d flow in all organs. Haemoglobin concentration decreased from 14.4+/- 0.8 to 10.8+/-1.3 mg dL(-1) after 45% blood loss. We conclude that las er Doppler flowmetry is useful for continuous measurement of microcirc ulatory blood flow in several organs simultaneously during haemorrhagi c hypovolaemia. It showed that microcirculatory blood flow in skeletal muscle is particularly sensitive to lesser degrees of blood loss duri ng anaesthesia. Hypovolaemia-induced slow wave flowmotion occurred onl y in skeletal muscle, which may be linked to fluid mobilization during haemorrhage.