Arterial blood gas test Diagnostic test Description , An arterial-blood gas test measures the amounts of arterial gases, such as oxygen and carbon dioxide. An ABG test requires that a small volume of blood be drawn from the radial artery with a syringe and a thin needle, but sometimes the femoral artery in the groin or another site is used.

1. PRESENTEDBY,
BHEEMALINGA,
AER.
ABG ANALYSIS.

2. DEFINITION
• An arterial blood gas (ABG) test measures the
acidity (pH) and the levels of oxygen and carbon
dioxide in the blood from an artery. This test is used
to check how well lungs are able to move oxygen
into the blood and remove carbon dioxide from the
blood.

3. Haemoglobin
PO2/PaO2 Base
Electrolytes
CO2 HCO-3
MAIN COMPONANTS IN ABG
PH O2 Saturation

4. COMPONENT
pH(7.35-7.45) ACIDOSIS ALKALOSIS
CO2 (35-45mmHg) ALKALOSIS ACIDOSIS
pO2 (80-100%) HYPOXEMIA O2 THERAPY
HCO3 (22-26mmol) ACIDOSIS ALKALOSIS
SaO2 (95-100%) HYPOXEMIA -----------------

5. INTERPRETATION IN DETAIL
pH - POWER OF HYDROGEN
• pH was originally acronym for French clause "pouvoir hydrogène,"
which can be translated into the English as "power of hydrogen," or
"potential of hydrogen." pH is used to quantify acidic or alkaline
nature of a chemical which is measured in terms of H+ ions
concentration.
• Normally the body’s pH is closely controlled at between 7.35 to 7.45.
This is achieved through buffering and excretion of acids. Buffers
include plasma proteins and bicarbonate(extra cellular) and proteins,
phosphate and haemoglobin(intra cellular).

6. CARBON MONOXIDE (CO2)
• Normally CO is <10%. In city dwellers or smokers levels can be raised up
to 10% but a level >10% indicates poisoning, commonly from poorly
ventilated boilers or old heating systems. CO2 is carbon dioxide
• In the body, most of the CO2 is in the form of a substance called
bicarbonate (HCO3-). Therefore, the CO2 blood test is really a measure
of your blood bicarbonate level
• At levels of 10 -20% symptoms such as nausea, headache vomiting and
dizziness will be predominant. At higher levels patients may experience
arrhythmias, cardiac ischemia, respiratory failure and seizures.

7. PaO2 AND PaCO2
• PaO2 is the partial pressure of oxygen in
arterial blood
• PaCO2 is the partial pressure of carbon dioxide
in arterial blood

8. BICARBONATE(HCO3)
o Bicarbonate is produced by the kidneys and acts as a
buffer to maintain a normal pH. The normal range for
bicarbonate is 22 – 26mmol/l.
o If there are additional acids in the blood the level of
bicarbonate will fall as ions are used to buffer these acids.
If there is a chronic acidosis additional bicarbonate is
produced by the kidneys to keep the pH in range.
o It is for this reason that a raised bicarbonate may be seen
in chronic type 2 respiratory failure where the pH remains
normal despite a raised CO2.

9. ELECTROLYTES
A venous or arterial blood gas is a good way to
quickly check potassium and sodium values. This is
particularly important in the immediate
management of cardiac arrhythmias as it gives an
immediate result.

10. GLUCOSE
• Don’t forget to check this. Glucose is especially
pertinent in the management of the patient who
has decreased consciousness or seizures. It is also
important in patients with known or suspected
diabetes.
• Glucose may also be raised in patients with severe
sepsis or other metabolic stress

11. ACIDOSIS - METABOLIC &
RESPIRATORY
• Acidosis is a process causing increased acidity in the
blood and other body tissues (i.e., an
increased hydrogen ion concentration). If not
further qualified, it usually refers to acidity of
the blood plasma. It is broadly divided into two as
metabolic and respiratory.

12. CAUSES OF METABOLIC ACIDOSIS
• hypoxemia
• hypovolemic shock
• starvation and diabetic ketoacidosis
• poisoning
• elevated levels of iron in the blood
• diarrhea and vomiting
• heart failure, cancer, seizures, liver failure, prolonged lack of
oxygen, and low blood sugar

13. CAUSES OF RESPIRATORY ACIDOSIS
• chronic airway conditions, like asthma
• injury to the chest
• obesity, which can make breathing difficult
• sedative misuse
• overuse of alcohol
• muscle weakness in the chest
• problems with the nervous system
• deformed chest structure

14. SIGNS & SYMPTOMS - ACIDOSIS
• rapid and shallow breathing.
• confusion.
• fatigue.
• headache.
• sleepiness.
• lack of appetite.
• jaundice.
• increased heart rate.

15. ALKALOSIS
• Alkalosis is the result of a process
reducing hydrogen ion concentration
of arterial blood plasma (alkalemia) alkalemia
occurs when the serum pH is higher than normal
(7.45 or higher). Alkalosis is usually divided into the
categories of respiratory alkalosis and metabolic
alkalosis or a combined respiratory/metabolic
alkalosis.[1]

16. CAUSES OF METABOLIC ALKALOSIS
• excess vomiting, which causes electrolyte loss
• overuse of diuretics
• adrenal disease
• a large loss of potassium or sodium in a short
amount of time
• antacids
• accidental ingestion of bicarbonate, which can be
found in baking soda
• laxatives
• alcohol abuse

17. CAUSES – RESPIRATORY ALKALOSIS
• hyperventilation, which commonly occurs with anxiety
• high fever
• lack of oxygen
• salicylate poisoning
• being in high altitudes
• liver disease
• lung disease

18. SIGNS & SYMPTOMS - ALKALOSIS
• Confusion (can progress to stupor or coma)
• Hand tremor.
• Lightheadedness.
• Muscle twitching.
• Nausea, vomiting.
• Numbness or tingling in the face, hands, or feet.
• Prolonged muscle spasms (tetany)

19. Respiratory and metabolic
compensation
LUNGS HCO3
CO2
KIDNEYSpH 7.40

20. Metabolic Compensation
o In response to a respiratory acidosis, for example
in CO2 retention secondary to COPD, the kidneys
will start to retain more HCO3 in order to correct
the pH.
o Here you would see a low normal pH with a high
CO2 and high bicarbonate.
o This process takes place over days.
o It is important to ensure that the compensation
that you see is appropriate, i.e. as you would
expect. If not then you should start to think about
mixed acid base disorders.

22. RADIAL

23. BRACHIAL

24. FEMORAL

25. BRACHIAL

26. DORSALIS PEDIS

27. WHY HEPARANIZED????
• it is essential for accurate results that the correct
volume of blood is sampled to achieve a correct
heparin concentration (and dilution, if liquid heparin is
used), and that blood and anticoagulant are well mixed
immediately after sampling. One of the most common
practical problems associated with blood-gas analysis is
inadequate anticoagulation and the formation of small
blood clots that can block the sample pathway of
blood-gas analyzers and invalidate results. Inadequate
mixing of specimen with heparin is usually the
problem. Clearly, the lower the heparin concentration
the greater is the risk that poor mixing technique will
give rise to inadequate anticoagulation and the
associated problems.

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