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C a = the oxygen concentration of arterial blood (oxygenated blood) C v = the oxygen concentration of venous blood (deoxygenated blood) The usual unit for a-vO 2 diff is millilitres of oxygen per 100 millilitres of blood (mL/100 mL), [1] however, particularly in medical uses, other units may be used, such as micro moles per millilitre (μmol/mL ...
The use of Doppler measurements which trace the echoes of the generated soundwaves received by the probe, enable the direction and the velocity of the blood flow, to be depicted. The overlay of color onto the Doppler information lets these images be seen more clearly. [8] The choice of a probe will depend on the depth needed to be studied.
Unlike arterial ultrasonography, venous ultrasonography is carried out with the probe in a transversal position, (perpendicular to the vein axis), displaying cross-sections of the veins. [4] All collateral veins are better detected this way, including perforator veins, but of most importance is the detection of venous thrombosis.
Lower limb venography is indicated in deep vein thrombosis, oedema with unknown cause, and congenital abnormality of the venous system. Less frequently it is used to demonstrate the incompetent valves of perforating veins. Doppler ultrasound is preferable rather than venography to access the competence of the veins.
Absence of the portal system in a first trimester case associated with hygroma and aorto-umbilical fistula. (A): Transverse plane of the upper abdomen with color Doppler applied, showing umbilical cord insertion, stomach, the prominent hepatic artery and no afferent liver venous perfusion; (B): midsagittal plane reconstructed from a three-dimensional volume acquisition were the crown-rump ...
Venous refill with dependency (should be less than 30 seconds) – the vein should bulge outward within 30 seconds of elevation for one minute. Buerger's test (assessment of arterial sufficiency): With the patient supine, note the colour of the feet soles. They should be pink. Then elevate both legs to 45 degrees for more than 1 minute.
One of the most common angiograms performed is to visualize the coronary arteries. A long, thin, flexible tube called a catheter is used to administer the X-ray contrast agent at the desired area to be visualized. The catheter is threaded into an artery in the forearm, and the tip is advanced through the arterial system into the major coronary ...
The peripheral vascular system is the part of the circulatory system that consists of the veins and arteries not in the chest or abdomen (i.e. in the arms, hands, legs and feet). [1] [2] The peripheral arteries supply oxygenated blood to the body, and the peripheral veins lead deoxygenated blood from the capillaries in the extremities back to ...