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    70 77 Blood flow of other organs
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    70 77 Blood flow of other organs

    Blood flow of other tissues: bone, fat, glands and connective tissue, calculated as the remainder of cardiac output.

    Blood flow of other organs is the part of cardiac output that goes to tissues not counted separately: bones and bone marrow, adipose (fat) tissue, connective tissue, thyroid and other endocrine glands, reproductive organs, bronchial vessels and others. Together they receive about 10% of cardiac output at rest, roughly 0.5 L/min. Although each of these tissues receives relatively little blood, their supply is important: bone marrow produces blood cells, the endocrine glands release hormones into the blood, and adipose tissue stores and releases energy.

    CirculationBone marrowEndocrine glands
    Share of cardiac output≈ 10%
    At rest≈ 0.5 L/min
    Includesbone, fat, glands, connective tissue
    Calculated asremainder of cardiac output
    Resting distribution of cardiac output with blood flow to other tissues highlighted: brain 13 percent, heart 4, skeletal muscle 20, skin 9, kidneys 20, abdominal organs 24, other tissues 10 Resting distribution of cardiac output (≈ 5 L/min) Brain 13% · ≈ 650 mL/min Heart (coronary) 4% · ≈ 215 mL/min Skeletal muscle 20% · ≈ 1030 mL/min Skin 9% · ≈ 430 mL/min Kidneys 20% · ≈ 950 mL/min Abdominal organs 24% · ≈ 1200 mL/min Other tissues 10% · ≈ 525 mL/min
    Figure 1. Resting distribution of a cardiac output of about 5 L/min (after Chapman and Mitchell, 1965). The highlighted bar shows blood flow to other tissues.

    This application estimates regional blood flow as a percentage of cardiac output and converts it into mL/min from the calculated cardiac output. In clinical practice, organ blood flow is measured invasively or with imaging (for example indicator dilution, Doppler ultrasound, PET or MRI perfusion).

    How it is obtained

    In this application, this value is the remainder: cardiac output minus the flows to the heart, brain, muscles, abdominal organs, kidneys and skin. Its changes therefore reflect, indirectly, the redistribution of blood among the main organs. For example, when much blood is directed to working muscles or the skin, the share of other tissues falls.

    Clinical significance

    • Bone: reduced blood supply can cause avascular necrosis (for example of the femoral head with corticosteroids, alcohol or after fracture) and slows fracture healing
    • Adipose tissue: blood flow increases after meals; in obesity it is reduced and less responsive, which is linked to insulin resistance
    • Thyroid: very high flow in Graves disease (a bruit may be heard over the gland)
    • Pregnancy: blood flow to the uterus and placenta rises greatly, making up a large share of the increased cardiac output
    Why it matters

    The distribution of blood among organs changes constantly with posture, meals, temperature, exercise and stress. A single value should be interpreted together with cardiac output and the flows to the main organs.

    References

    1. Vander A, Sherman J, Luciano D. Human Physiology: The Mechanisms of Body Function. 8th ed. Boston: McGraw-Hill; 2001. Fig. 14-9 (after Chapman CB, Mitchell JH. Sci Am. 1965). Data: BioNumbers BNID 109465

    This article is for general information and does not replace a consultation with a doctor. Measurements must be interpreted by a physician together with symptoms and other tests.

    Published on 30 April 2024