Question: What Is Base Excess In Arterial Blood Gases?

The base excess It is defined as the amount of acid required to restore a litre of blood to its normal pH at a PaCO2 of 40 mmHg. The base excess increases in metabolic alkalosis and decreases (or becomes more negative) in metabolic acidosis, but its utility in interpreting blood gas results is controversial.

What does a positive base excess mean?

Together with the bicarbonate, the base excess gives you an indication of the metabolic component of the blood gas results. A positive base excess means excess base, i.e. a metabolic alkalosis, whereas a negative base excess means reduced base, i.e. a metabolic acidosis.

What is base excess vs base deficit?

A positive number is called a base excess and indicates a metabolic alkalosis. A negative number is called a base deficit and indicates a metabolic acidosis.

What is base excess used for?

Base excess of extracellular fluid is a quantity that reflects only the non-respiratory (metabolic) component of acid-base disturbances. It is the most used “non-respiratory” quantity for the diagnosis of acid-base disturbances and is calculated and presented by all blood gas analyzers produced today worldwide.

What is base deficit on ABG?

A base deficit indicates an excess of acid. It refers to the amount of base needed to titrate a serum pH back to normal (healthy human-arterial blood pH varies between 7.35 and 7.45) when the contribution of respiratory factors is taken out of the equation. Base deficit is usually reported as a negative base excess.

What causes high base excess?

A high base excess (> +2mmol/L) indicates that there is a higher than normal amount of HCO3– in the blood, which may be due to a primary metabolic alkalosis or a compensated respiratory acidosis. 6

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What is normal base excess?

Base excess or base deficit is characterized by the amount of base that is required to normalize the pH of the blood. Normal values range from -2 to +2 mEq/L.

What is a normal bicarb?

Normal bicarbonate levels are: 23 to 30 mEq/L in adults.

What causes high anion gap metabolic acidosis?

The most common causes of high anion gap metabolic acidosis are: ketoacidosis, lactic acidosis, kidney failure (also known as renal failure), and toxic ingestions.

What causes metabolic acidosis?

Metabolic acidosis develops when too much acid is produced in the body. It can also occur when the kidneys cannot remove enough acid from the body.

How do you interpret ABG and VBG?

The values on a VBG and ABG are comparable (arterial and venous values are NOT significantly different for practical purposes) except in the cases of O2 and CO2. The arterial PO2 is typically 36.9 mmHg greater than the venous with significant variability (95% confidence interval from 27.2 to 46.6 mmHg).

How do you correct ABG base deficit?


  1. Bicarbonate deficit: The amount of bicarbonate req’d to correct a metabolic acidosis can be estimated from the following formula:
  2. Volume of distribution (Vd) = Total body weight (kg) x [0.4 + (2.4/[HCO3-])
  3. (Deficit) mEq of NaHCO3 = Vd x target change in [HCO3-]

What is blood base?

Blood is normally slightly basic, with a normal pH range of about 7.35 to 7.45. Usually the body maintains the pH of blood close to 7.40. A doctor evaluates a person’s acid-base balance by measuring the pH and levels of carbon dioxide (an acid) and bicarbonate (a base) in the blood.

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How is base excess calculated?

Most equations used for calculation of the base excess (BE, mmol/l) in human blood are based on the fundamental equation derived by Siggaard-Andersen and called the Van Slyke equation: BE = Z x [[cHCO3-(P) – C7. 4 HCO3-(P)] + beta x (pH -7.4)].