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Arterial blood gas
 
 
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An arterial blood gas (ABG) is a blood test
Blood test

A blood test is a medical laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick....
 that is primarily performed using blood
Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
 from an artery
Artery

Arteries are blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood....
. It involves puncturing an artery with a thin needle and syringe and drawing a small volume of blood. The most common puncture site is the radial artery
Radial artery

In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm....
 at the wrist
Wrist

In human anatomy, the wrist is the flexible and narrower connection between the forearm and the hand. The wrist is essentially a double row of small short bones, called carpals, intertwined to form a malleable hinge....
, but sometimes the femoral artery
Femoral artery

The femoral artery is a large artery in the muscles of the thigh....
 in the groin
Groin

In human anatomy, the groin areas are the two wikt:crease at the junction of the torso with the legs, on either side of the pubic area. A pulled groin muscle usually refers to a pulled Adductor muscles of the hip....
 or other sites are used. The blood can also be drawn from an arterial catheter.

The test is used to determine the pH
PH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
 of the blood, the partial pressure
Partial pressure

In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
 of carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 and oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
, and the bicarbonate
Bicarbonate

In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid. Its chemical formula is HCO3−....
 level.






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An arterial blood gas (ABG) is a blood test
Blood test

A blood test is a medical laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick....
 that is primarily performed using blood
Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
 from an artery
Artery

Arteries are blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood....
. It involves puncturing an artery with a thin needle and syringe and drawing a small volume of blood. The most common puncture site is the radial artery
Radial artery

In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm....
 at the wrist
Wrist

In human anatomy, the wrist is the flexible and narrower connection between the forearm and the hand. The wrist is essentially a double row of small short bones, called carpals, intertwined to form a malleable hinge....
, but sometimes the femoral artery
Femoral artery

The femoral artery is a large artery in the muscles of the thigh....
 in the groin
Groin

In human anatomy, the groin areas are the two wikt:crease at the junction of the torso with the legs, on either side of the pubic area. A pulled groin muscle usually refers to a pulled Adductor muscles of the hip....
 or other sites are used. The blood can also be drawn from an arterial catheter.

The test is used to determine the pH
PH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
 of the blood, the partial pressure
Partial pressure

In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
 of carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 and oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
, and the bicarbonate
Bicarbonate

In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid. Its chemical formula is HCO3−....
 level. Many blood gas analyzers will also report concentrations of lactate
Lactate

Lactate may refer to:*The act of lactation*A salt or ester of lactic acid...
, hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
, several electrolyte
Electrolyte

An electrolyte is any substance containing free ions that behaves as an electrical conductor medium. Because they generally consist of ions in solution, electrolytes are also known as ionic solutions, but molten electrolytes and solid electrolytes are also possible....
s, oxyhemoglobin, carboxyhemoglobin
Carboxyhemoglobin

Carboxyhemoglobin is a stable complex of carbon monoxide and hemoglobin that forms in red blood cells when carbon monoxide is inhaled, and hinders delivery of oxygen to the body....
 and methemoglobin. ABG testing is mainly used in pulmonology
Pulmonology

File:Lungs_open.jpgIn medicine, pulmonology is the specialty that deals with diseases of the lungs and the respiratory tract. It is called chest medicine and respiratory medicine in some countries and areas....
, to determine gas exchange
Gas exchange

Gas exchange or respiration takes place at a respiratory surface?a boundary between the external environment and the interior of the body....
 levels in the blood related to lung
Lung

The lung is the essential respiration organ in air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located in the chest on either side of the heart....
 function, but has a variety of applications in other areas of medicine. Combinations of disorders can be complex and difficult to interpret, so calculators , nomograms, and rules of thumb are commonly used.

Extraction and analysis


Arterial blood for blood gas analysis is usually extracted by a phlebotomist
Phlebotomist

A phlebotomist is an individual trained to draw blood, either for laboratory tests or for blood donations....
, nurse
Nurse

A nurse is a healthcare professional, who along with other health care professionals, is responsible for the treatment, safety, and recovery of Acute or Chronic ill or injured people, health maintenance of the healthy, and treatment of life-threatening emergencies in a wide range of health care settings....
, or respiratory therapist. Blood is most commonly drawn from the radial artery
Radial artery

In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm....
 because it is easily accessible, can be compressed to control bleeding, and has less risk for occlusion. The femoral artery
Femoral artery

The femoral artery is a large artery in the muscles of the thigh....
 (or less often, the brachial artery
Brachial artery

The brachial artery is the major blood vessel of the upper arm.It is a continuation of the axillary artery beyond the lower margin of teres major muscle....
) is also used, especially during emergency situations or with children. Blood can also be taken from an arterial catheter already placed in one of these arteries.

The syringe is pre-packaged and contains a small amount of heparin
Heparin

Heparin, a highly-sulfated glycosaminoglycan, is widely used as an injectable anticoagulant and has the highest negative charge density of any known biomolecule....
, to prevent coagulation
Coagulation

Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis , wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop hemorrhage and begin repair of the damaged vessel....
 or needs to be heparinised, by drawing up a small amount of heparin and squirting it out again. Once the sample is obtained, care is taken to eliminate visible gas bubbles, as these bubbles can dissolve into the sample and cause inaccurate results. The sealed syringe is taken to a blood gas analyzer. If the sample cannot be immediately analyzed, it is chilled in an ice bath in a glass syringe to slow metabolic processes which can cause inaccuracy. Samples drawn in plastic syringes should not be iced and should always be analyzed within 30 minutes.

The machine used for analysis aspirates this blood from the syringe and measures the pH
PH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
 and the partial pressure
Partial pressure

In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
s of oxygen and carbon dioxide. The bicarbonate concentration is also calculated. These results are usually available for interpretation within five minutes.

Standard blood tests can also be performed on arterial blood, such as measuring glucose
Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
, lactate
Lactic acid

Lactic acid , also known as milk acid, is a chemical compound that plays a role in several biochemistry processes. It was first isolated in 1780 by a Swedish chemist, Carl Wilhelm Scheele, and is a carboxylic acid with a chemical formula of C3H6O3....
, hemoglobins, dys-haemoglobins, bilirubin
Bilirubin

Bilirubin is the yellow breakdown product of normal heme catabolism. Heme is formed from hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile, and its levels are elevated in certain diseases....
 and electrolyte
Electrolyte

An electrolyte is any substance containing free ions that behaves as an electrical conductor medium. Because they generally consist of ions in solution, electrolytes are also known as ionic solutions, but molten electrolytes and solid electrolytes are also possible....
s.

Reference ranges and interpretation

These are typical reference ranges, although various analysers and laboratories may employ different ranges.
Analyte Range Interpretation
pH 7.35 - 7.45 The pH
PH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
 or H+ indicates if a patient is acidemic (pH < 7.35; H+ >45) or alkalemic (pH > 7.45; H+ < 35).
H+ 35 - 45 nmol
Mole (unit)

The mole is a Units of measurement of amount of substance: it is an SI base unit, and one of the few units used to measure this physical quantity....
/l
Litre

The litre or liter is a unit of volume. There are two official symbols: the Latin letter L in lower and upper case . The lower case L is often written as a cursive l to avoid confusion with the number 1 in antiqua fonts....
 (nM
Concentration

In chemistry, concentration is the measure of how much of a given chemical substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent....
)		 See above.
PO2 9.3-13.3 kPa
KPA

KPA may refer to:* Kenya Ports Authority* Kilopascal , a unit of pressure* Known-plaintext attack, a method of cryptanalysis* Korean People's Army...
 or 80-100 mmHg		2 is 70-100 mmHg (age-dependent). >A low O2 indicates that the patient is not respiring properly, and is hypoxemic. At a PO2 of less than 60 mm Hg, supplemental oxygen should be administered. At a PO2 of less than 26 mm Hg, the patient is at risk of death and must be oxygenated immediately.
PCO2 4.7-6.0 kPa or 35-45 mmHg The carbon dioxide and partial pressure (PCO2
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
) indicates a respiratory
Respiration (physiology)

In animal physiology, respiration is the transport of Oxygen from the outside air to the cells within Tissue s and the transport of carbon dioxide in the opposite direction....
 problem: for a constant metabolic rate, the PCO2
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 is determined entirely by ventilation. A high PCO2
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 (respiratory acidosis
Respiratory acidosis

Respiratory acidosis is acidosis due to decreased Ventilation of the lung alveoli, leading to elevated artery carbon dioxide concentration ....
) indicates underventilation, a low PCO2
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 (respiratory alkalosis
Respiratory alkalosis

Respiratory alkalosis results from increased alveoli respiration leading to decreased plasma carbon dioxide concentration. This leads to decreased hydrogen ion and freely ionized blood calcium concentrations....
) hyper- or overventilation. PCO2 levels can also become abnormal when the respiratory system is working to compensate for a metabolic issue so as to normalize the blood pH. An elevated PCO2 level is desired in some disorders associated with respiratory failure
Respiratory failure

The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges....
; this is known as permissive hypercapnia
Permissive hypercapnia

Permissive hypercapnia is hypercapnia, , in respiratory insufficiency patients in which oxygenation has become so difficult that the optimal mode of mechanical ventilation is not capable of exchanging enough carbon dioxide....
.
HCO3- 22–26 mmol/l The HCO3- ion indicates whether a metabolic
Metabolism

Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
 problem is present (such as ketoacidosis
Ketoacidosis

Ketoacidosis is a type of metabolic acidosis which is caused by high concentrations of ketone bodies, formed by the breakdown of fatty acids and the deamination of amino acids....
). A low HCO3- indicates metabolic acidosis
Metabolic acidosis

In medicine, metabolic acidosis is a process which if unchecked leads to acidemia, i.e. blood pH is low due to increased production of hydrogen by the body or the inability of the body to form bicarbonate in the kidney....
, a high HCO3- indicates metabolic alkalosis
Metabolic alkalosis

Metabolic alkalosis is a metabolic condition in which the pH of the blood is elevated beyond the normal range. This is usually the result of decreased hydrogen ion concentration, leading to increased bicarbonate, or alternatively a direct result of increased bicarbonate concentrations....
. HCO3- levels can also become abnormal when the kidneys are working to compensate for a respiratory issue so as to normalize the blood pH.
SBCe 21 to 27 mmol/l the bicarbonate concentration in the blood at a CO2
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 of 5.33 kPa, full oxygen saturation and 37 degrees Celsius.
Base excess
Base excess

In human physiology, base excess refers to the amount of acid required to return the blood pH of an individual to the reference interval pH with the amount of carbon dioxide held at a standard value....
 -3 to +3 mmol/l- | HPO42-
Phosphate

A phosphate, an inorganic chemical, is a Salt of phosphoric acid. Inorganic phosphates are mining to obtain phosphorus for use in agriculture and industry....
 | 0.8 to 1.5 mM | |- | total CO2 (tCO2 (P)c) | 25 to 30 mmol/l | This is the total amount of CO2, and is the sum of HCO3- and PCO2 by the formula:
tCO2 = [HCO3-] + a*PCO2, where a=0.226 mM/kPa, HCO3- is expressed in millimolar concentration
Concentration

In chemistry, concentration is the measure of how much of a given chemical substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent....
 (mM) (mmol/l) and PCO2 is expressed in kPa |- | total O2 (tO2e) | | This is the sum of oxygen solved in plasma and chemically bound to hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
.


Contamination with room air will result in abnormally low carbon dioxide and (generally) normal oxygen levels. Delays in analysis (without chilling) may result in inaccurately low oxygen and high carbon dioxide levels as a result of ongoing cellular respiration.

Lactate level analysis is often featured on blood gas machines in neonatal wards, as infants often have elevated lactic acid
Lactic acid

Lactic acid , also known as milk acid, is a chemical compound that plays a role in several biochemistry processes. It was first isolated in 1780 by a Swedish chemist, Carl Wilhelm Scheele, and is a carboxylic acid with a chemical formula of C3H6O3....
.

See also

  • Acid-base homeostasis
    Acid-base homeostasis

    Acid-base homeostasis is the part of human homeostasis concerning the proper balance between acids and Chemical base, in other words the pH. The body is very sensitive to its pH level....
  • Anion gap
    Anion gap

    The anion gap is used to aid in the differential diagnosis of metabolic acidosis.Although the term "anion gap" usually implies "serum anion gap", the Urine anion gap is also a clinically useful measure....
  • Mechanical ventilation
    Mechanical ventilation

    In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous respiration .Mechanical ventilation is typically used after an invasive intubation, a procedure wherein an endotracheal tube or tracheostomy tube is inserted into the airway....


External links

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