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A low PaO 2 indicates that the patient's current minute ventilation (whether high or normal) is not enough to allow adequate oxygen diffusion into the blood. Therefore, the A–a gradient essentially demonstrates a high respiratory effort (low arterial PaCO 2) relative to the achieved level of oxygenation (arterial PaO 2). A high A–a gradient ...
Mathematically, if the change in the numerator is similar to the change in the denominator, the delta ratio will be close to 1. Since the anions are unable to diffuse out of the bloodstream, while bicarbonate and hydrogen ions diffuse with ease (as H 2 CO 3, carbonic acid), the usual result will be closer to a delta ratio of 1 to 2.
If one were to consider humidified air (with less oxygen), then the ideal v/q ratio would be in the vicinity of 1.0, thus leading to concept of ventilation-perfusion equality or ventilation-perfusion matching. This matching may be assessed in the lung as a whole, or in individual or in sub-groups of gas-exchanging units in the lung.
A high gradient (> 1.1 g/dL, >11 g/L) indicates the ascites is due to portal hypertension, either liver related or non-liver related, with approximately 97% accuracy. [2] This is due to increased hydrostatic pressure within the blood vessels of the hepatic portal system , which in turn forces water into the peritoneal cavity but leaves proteins ...
Enzyme activity is commonly used for e.g. liver function tests like AST, ALT, LD and γ-GT in Sweden. [5] Percentages and time-dependent units (mol/s) are used for calculated derived parameters, e.g. for beta cell function in homeostasis model assessment or thyroid's secretory capacity. [citation needed]
The proportion of AST to ALT in hepatocytes is about 2.5:1, but because AST is removed from serum by the liver sinusoidal cells twice as quickly (serum half-life t 1/2 = 18 hr) compared to ALT (t 1/2 = 36 hr), so the resulting serum levels of AST and ALT are about equal in healthy individuals, resulting in a normal AST/ALT ratio around 1.
The E/A ratio is a marker of the function of the left ventricle of the heart. It represents the ratio of peak velocity blood flow from left ventricular relaxation in early diastole (the E wave) to peak velocity flow in late diastole caused by atrial contraction (the A wave). [ 1 ]
The respiratory exchange ratio (RER) is the ratio between the metabolic production of carbon dioxide (CO 2) and the uptake of oxygen (O 2). [3] [4] The ratio is determined by comparing exhaled gases to room air. Measuring this ratio is equal to RQ only at rest or during mild to moderate aerobic exercise without the accumulation of lactate.