How does arterial blood gas analysis work

Learn about the symptoms and treatment of each. When blood sugar levels…. A blood glucose test measures the amount of glucose in your blood.

This simple test involves giving a small sample of blood. Read on to find out what…. Health Conditions Discover Plan Connect. Blood Gas Test. Medically reviewed by Elaine K.

Luo, M. Purpose Risks Procedure Results What is a blood gas test? Why is a blood gas test done? What are the risks of a blood gas test? How is a blood gas test performed?

Interpreting the results of a blood gas test. Read this next. CO2 Blood Test. Medically reviewed by Debra Sullivan, Ph. A measurement of how much oxygen is carried by the hemoglobin in red blood cells is oxygen saturation.

If the values are derived from capillary or venous samples, the reference range for the normal values will be slightly different.

An electrolyte imbalance in the body is the basis of metabolic acidosis, which is a serious electrolyte disorder. There are three major causes of Metabolic Acidosis: Excessive acid production, Bicarbonate loss, and a reduced ability to remove excess acid from the body.

The Alkalosis of the metabolism is a condition in which the tissues have a pH that is above normal 7. It results from reduced hydrogen ion concentration, which in turn causes an increase in bicarbonate, or else it is a direct consequence of an increase in bicarbonate concentrations. As a result of Respiratory Acidosis, the lungs are unable to remove all of the carbon dioxide produced by the body.

In turn, body fluids become excessively acidic, especially blood. A medical condition involving elevated blood pH and a reduction in arterial carbon dioxide levels, respiratory Alkalosis occurs when increased respiration elevates blood pH beyond the normal range 7. Glucose Meter Sensa Cores Gluco Spark , An advanced Glucometer provides accurate results in 5 sec and comes with no coding, which is easy to use and easy to afford.

Lactate Meter Lacto Spark is a hand-held lactate analyzer that requires just 0. Hemoglobin Meter Sensa Cores Hemo Spark is an in vitro diagnostic device that is used for quantitative testing of total hemoglobin in the blood Generic Portfolio A premier alternative manufacturer of Reagents and consumables for Blood Gas, Hematology and Electrolyte worldwide. Blood gas analysis is performed on blood collected from the artery.

It measures the partial pressure of Oxygen and Carbon dioxide in the blood, as well as Oxygen content, Oxygen saturation, Bicarbonate content and Blood pH. If blood is taken from the wrist, you will be seated with your arm extended and your wrist resting on a small pillow. The health professional taking the blood may rotate your hand back and forth and feel for a pulse in your wrist. A procedure called the Allen test may be done to make sure that the blood flow to your hand is normal.

An ABG test will not be done on an arm used for dialysis or if there is an infection or inflammation in the area of the puncture site. Collecting blood from an artery is more painful than collecting it from a vein. That's because the arteries are deeper and are surrounded by nerves. Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide.

Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you. The concentration of oxygen being breathed, called the fraction of inhaled oxygen FiO2 , is also usually reported. This is only useful if you are receiving oxygen therapy from a tank or are on a ventilator.

Many conditions can change blood gas levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health. Russo MD - Internal Medicine. Author: Healthwise Staff. Medical Review: E. This information does not replace the advice of a doctor. The oxygen delivery function of hemoglobin, i. In the deoxy state hemoglobin has low affinity for oxygen and in the oxy state it has high affinity for oxygen.

A number of environmental factors in blood determine the hemoglobin state deoxy or oxy and thereby the relative affinity for oxygen. The most significant of these is the p O 2. Hemoglobin present in blood with relatively high p O 2 has much greater affinity for oxygen than hemoglobin present in blood with relatively low p O 2. The oxygen dissociation curve ODC describes this relationship graphically Fig. The percentage of total hemoglobin saturated with oxygen i. By contrast in the milieu of the tissues where p O 2 is much lower, hemoglobin affinity for oxygen is also much lower and oxygen is released from hemoglobin to the tissues.

Relationship between the amount of oxygen dissolved in blood PO 2 and the amount of oxygen carried by hemoglobin SO 2. If p O 2 a is reduced, then less oxygen can be carried by hemoglobin i. Examination of the oxygen dissociation curve Fig. The delivery of oxygen to tissues becomes increasingly compromised as p O 2 a falls below this level. All biochemical reactions are sensitive to change in pH, so that optimum survival and function of cells require that blood pH is maintained within the narrow range of 7.

Even mild excursion outside the normal range has multiple deleterious effects, and a pH of less than 6. The maintenance of normal blood pH is a complex synergy of action involving the chemical buffers present in blood principally bicarbonate , red blood cells and the function of three organs: the kidneys, lungs and brain stem.

The following discussion assumes an outline understanding of some basic concepts: pH, acids, bases and buffers see BOXES for a reminder. Pure water has a pH of 7 neutral, i. From this equation: pH 7. An acid is a substance that dissociates in solution to release hydrogen ions.

A base accepts hydrogen ions. By contrast, carbonic acid is a weak acid ; it dissociates much less easily, yielding fewer hydrogen ions and therefore higher pH than hydrochloric acid. A chemical buffer is a compound in solution the conjugate base of a weak acid that resists change in the pH of the solution when acid is added, by "mopping up" hydrogen ions.

The principal buffer in blood is bicarbonate, which is the conjugate base of the weak acid, carbonic acid. The presence of bicarbonate in blood serves to minimize the change in pH of blood that occurs when acids produced during cell metabolism are released from cells to blood.

To illustrate the buffering action of bicarbonate consider a solution of sodium bicarbonate the buffer to which a strong acid, in this case hydrochloric acid, is added. The hydrogen ions resulting from strongly dissociating hydrochloric acid are incorporated in to the weak acid, carbonic acid thus:. The pH of any buffered solution is governed by the relative concentration of the weak acid and its conjugate base according to the following so-called Henderson-Hasselbalch equation for bicarbonate buffer in blood:.

From this equation it is possible to derive an important relationship between three ABG parameters: pH, pCO 2 a and bicarbonate that aids understanding of acid-base balance see text.

To understand the maintenance of blood pH and the other ABG parameters used to assess acid-base balance, it is useful to consider the way carbon dioxide CO 2 is transported in blood from tissue cells to lungs. In the microvasculature of tissues CO 2 diffuses from cells —where it is produced — to blood due to the prevailing p CO 2 gradient p CO 2 in tissue cells higher than that in blood.

The potentially dangerous fall in red-cell pH induced by the influx of hydrogen ions is ameliorated by them combining with reduced hemoglobin hemoglobin, now stripped of its oxygen is acting as a buffer here. When venous blood arrives in the capillary networks that surround the alveoli in the lungs, the small amount of CO 2 dissolved in blood passes across the alveolar membrane due to the prevailing p CO 2 gradient.

This loss of CO 2 from blood reverses the direction of the above equation should now be read from right to left reflecting a reversal of the sequence of events that occurred in the microvasculature of the tissues.

So, in blood perfusing the alveoli, hemoglobin releases hydrogen ions as it combines with inspired oxygen. These hydrogen ions are buffered by combine with bicarbonate to form carbonic acid, which dissociates to carbon dioxide CO 2 and water.

The CO 2 diffuses from blood to alveoli. The process is continuously regulated so that the amount of CO 2 being removed from blood at the lungs equals the amount of CO 2 being added to the blood in the tissues. This simple relationship, which is central to an understanding of all essential aspects of acid-base balance and interpretation of patient ABG results, states that pH of arterial blood is a function of both p CO 2 a and bicarbonate concentration.