Arterial Blood Gas (ABG)Procedure and Interpretation \Mohammad Al-me`ani. , MSN, RN.

Mohammad Al-me`ani. , MSN, RN.

 Understand ABG and its terms.
 Know some of the indication and contraindications
for performing an arterial puncture.
 Be able to demonstrate the technique for performing
an arterial puncture.
 Understand the interpretation of ABG.
Mohammad Al-me`ani, 2020 2

 Arterial blood gas analysis is an essential part
for diagnosing and managing the patient's
oxygenation status, ventilation status and acid
base balance.
 Drawn from arteries( radial, brachial and
femoral).
 It is an invasive procedure

 Drawn from arteries( radial, brachial and
femoral).
 Radial artery- best site - located superficially,
easy to palpate & stabilize .
 It is an invasive procedure

 Assess the ventilator status, oxygenation and
acid base status.
 Assess the response to an intervention.
 Regulate electrolyte therapy.
 Establish preoperative baseline parameters.

1. Bleeding diathesis.
2. AV fistula .
3. Severe peripheral vascular disease, absence
of an arterial pulse .
4. Infection over site.

1. The most common complication from an arterial puncture is
hematoma at the site.
2. Less common but important complications are thrombus in
the artery and infection at the site.
3. Pain

 the radial artery is superficial, has collaterals
and is easily compressed, It should almost
always be the first choice.
 Other arteries (femoral, dorsalis pedis,
brachial) can be used in emergencies

1. Wash your hands.
2. introduce yourself to the patient and clarify
their identity.
3. Explain what you would like to do and
obtain consent.
4. This is a slightly uncomfortable procedure
so you should let the patient know this.

 2ml syringe with heparin
 local anesthetic
 Alcohol gel
 Gauze
 Gloves
 Sharps box

 The modified Allen test is used to
evaluate the adequacy of collateral
circulation before cannulating the
radial artery.
A. Firmly occlude both the ulnar and
radial arteries of one hand while the
person makes a fist several times.
This causes the hand to blanch

B. Ask the person to open the hand without
hyperextending it; then release pressure on the
ulnar artery while maintaining pressure on the
radial artery.
C. Adequate circulation is suggested by a palmar
blush, a return to the normal color of the hand in
approximately 2 to 5 seconds.

 Wash hands
 Clean equipment tray as per guidelines
 Collect equipment

 Gel hands
 Don clean non sterile gloves
 Prepare equipment
 Ensure patient wrist supported comfortably
 Relocate maximum pulsation with finger tips

 Keeping one finger on pulse
 Clean in front of finger with alcohol wipe for
30 sec – allow to air dry
 Take pre-prepared needle and syringe

 Hold syringe into patient’s palm Gently but
steadily insert needle at 30-45˚
 Allow 1- 2mls of blood into syringe

 On removal of needle apply pressure to site
for minimum of 5 minutes
 Dispose of needle immediately into sharps bin
 Expel any air or bubbles and apply cap

 Roll or invert syringe for min of 30 secs to mix
heparin
 Transport labelled syringe to analyser within 15 mins
 Eject initial 1 or 2 drops of sample prior to
introduction into analyser

 Dispose and clean equipment as policy
 Wash hands
 Document results in patient notes

 The primary aim of keeping this delicate balance is to
preserve the Homeostasis i.e. the highly complex interactions
that maintain all body systems to functioning within a normal
range.
 Any extreme change in this balance may result in disastrous
changes e.g. denaturation of proteins & shut down of all
enzymatic and metabolic processes. Such disturbed
environment would be incompatible with life.

 The 2 body systems that always try to achieve this balance are:
1. The Kidneys: through manipulating the amount of HCO3- and
H+ (By secretion, excretion or reabsorption).
2. The Lungs: through manipulating the amount of CO2
(Increase or decrease the respiratory rate)

 If there is a defect in one system, the other one tries to buffer its
effects in order to reach the balance required for proper
homeostatic functioning (the principle of Compensation).
 The response of each system to make that balance varies e.g.
 The Lungs: Respond in minutes.
 The Kidneys: Respond in hours to days.

• Measurement of acidity or pH
alkalinity, based on the hydrogen
(H+) ( 7-35 - 7.45)
PH
• The partial pressure oxygen that is
dissolved in arterial plasma. (80 -
100 mm Hg)
PaO2
• The amount of carbon dioxide
dissolved in arterial blood. (35 - 45
mmHg)
PaCO2

• The calculated value of the
serum m HCO
concentration of
bicarbonate (22- 26 mEq/L)
HCO3
• The partial pressure oxygen
that is dissolved in arterial
plasma. (80 - 100 mm Hg)
SaO2

1. Respiratory Acidosis
 It is defined as a pH less than 7.35 with a Paco2 greater than
45 mmHg.
 Acidosis is caused by an accumulation of co2, thus lowering
the pH of the blood.

 any condition that results in hypoventilation can cause
respiratory acidosis ,includes:
1. Central nervous system depression related to head injury or
cerebrovascular stroke .
2. Medications such as : narcotics , sedatives .
3. Spinal coed injuries & neuromuscular disease .
4. Pulmonary disorders such as : atelectasis ,pneumonia ,
pneumothorax & pulmonary edema .
5. Hypoventilation due to pain , chest wall injury.
6. COPD

 Signs and symptoms
1. Dyspnea
2. Shallow respiration
3. headache
4. Confusion
5. Drowsiness
6. Tachycardia
7. Arrhythmias

 Management of Respiratory Acidosis:
1. Oxygen & suctioning as needed.
2. "Pulse oximetry & ABG follow up.
3. Treatment of the cause e.g. pneumothorax, severe
pain (Rib fracture) and CNS depressants toxicity.
4. If the cause can not be readily resolved, mechanical
ventilation.

1. Respiratory Alkalosis
 It is defined as a pH greater than 7.45 with a Paco2 lesser
than 35 mmHg.
 Alkalosis is excessive wash of co, (hyperventilation), thus
increasing the pH of the due to blood.

 any condition that results in hyperventilation can cause
Respiratory Alkalosis ,includes:
1. Anxiety
2. Fear
3. Pain
4. Fever
5. Sepsis
6. Chronic liver disease

1. Confusion
2. light headness
3. Inability to concentrate
4. Blurred vision
5. Palpitation
6. Dry mouth
7. Diaphoresis

 Management of Respiratory Alkalosis :
1. Oxygen for any patient with respiratory distress of
any origin.
2. "Pulse oximetry & ABG follow up.
3. Treatment of the cause.
4. If panic attack: calm the patient, oxygen,
Benzodiazepines.

 It is defined as a pH less than 7.35 with a HCO3 less than
22 mEqL..

 Any disorder that will lead to tissue hypo perfusion whatever
the cause will lead eventually to increase in lactic acid
production resulting in Metabolic Acidosis.,includes:
1. Renal failure (Sulphuric, phosphoric, uric adids.etc)
2. Diabetic Keteacidosis (Ketoacids.)
3. Anaerobic metabolism (Lactic acid)
4. Convulsions (Lactic acid) .
5. "Drugs : Salicyliates, methanol, ethylene glycol, metformin
intoxication.
6. Diarrhea.

1. Restlessness
2. lethargy
3. headache
4. Confusion
5. Coma
6. Cardiac arrest
7. Nausea
8. Vomiting

 Management of Respiratory Acidosis:
1. Treatment of the cause should be our primary aim.
2. Maintain adequate tissue oxygenation &
Hemodynamic stability.
3. In severe cases, we can use Sodium
Bicarbonate(NAHCO3) as a buffer to maintain a pH
value that is compatible with a proper homeostatic
functioning.

 It is defined as a pH greater than 7.45 with a HCO3 greater
than 26 mEqL.

 Causes
 is due to excessive acid loss (repeated vomiting a nasogastric
suction) OR bicarbonate retention e.g overuse of sodium
bicarbonate.
1. Vomiting
2. Gastric section
3. During treatment with loop and thiazide diuretics .
4. Overuse of antacid salts .

1. Lethargy
2. Nausea
3. Vomiting
4. Coma
5. Seizures
6. Dizziness
7. Weakness in muscles
8. Disorientation
9. Respiratory depression

 Management of Respiratory Alkalosis :
1. Give the patient dimox (carbonic anhydrase
inhibitors) to shifting HCO3.

Step 1: Assess the pH
 If below 7.35 = acidotic
 If above 7.45 = alkalotic
Step 2:
 1- Assess the paCO2 level
 If below 35 = Respiratory alkalosis element
 If above 45 = Respiratory acidosis element
 2- Assess HCO3 value
 If below 22 Metabolic acidosis element .
 If above 26 = Metabolic alkalosis element.

Step 3: Determine if there is a compensatory
mechanism working to try to correct the pH (Full
or partial).
1. Full compensation
PH (normal)
PaCO2(abnormal )
HCO3(abnormal )

2. Partial compensation
PH (abnormal)
PaCO2(abnormal )
HCO3(abnormal )

3. Non- compensation
PH
PaCO2(normal )
HCO3(abnormal )
Only one of the readings is normal and the other is abnormal

3. Compound mixed
PH (abnormal)
PaCO2(abnormal )
HCO3(abnormal )
All the component acidosis or alkalosis

1. pH:7.51, pCO2 :40, HCO3: 31
a. Normal
b. Uncompensated metabolic alkalosis
c. partially compensated respiratory acidosis
d. Uncompensated respiratory alkalosis

2. pH: 7.33, pCO2 :29, HCO3: 16
a. Uncompensated respiratory alkalosis
b. Uncompensated metabolic acidosis
c. Partially compensated respiratory acidosis
d. Partially compensated metabolic acidosis

3. pH: 7.40, pCO2 :40, HCO3: 24
a. Normal
b. uncompensated metabolic acidosis
c. partially compensated respiratory acidosis
d. partially compensated metabolic acidosis

4. pH : 7.12, pCO2: 60, HCO3: 29
a. Uncompensated metabolic acidosis
b. Uncompensated respiratory acidosis

5. pH :7.48, pCO2: 30, HCO3:23
a. Uncompensated metabolic alkalosis
b. Uncompensated respiratory alkalosis
c. Partially compensated respiratory alkalosis
d. Partially compensated metabolic alkalosis

6. pH :7.52, pCO2: 47, HCO3: 30
a. Uncompensated metabolic alkalosis
b. Uncompensated respiratory alkalosis
c. Partially compensated respiratory alkalosis
d. Partially compensated metabolic alkalosis

7. pH :7.30, pCO2 :59. HCO3: 28
a. Uncompensated metabolic acidosis
b. Uncompensated respiratory acidosis

1. B – pH is high, Bicarb is high, Co2 is normal and not attempting to
correct the problem so this metabolic alkalosis is uncompensated.
2. D – pH is low, Bicarb is low, Co2 is low and attempting to correct
the problem (but has not completely helped) so this is partially
compensated metabolic acidosis.
3. A – pH, Bicarb and Co2 are within normal ranges so this is a
normal ABG
4. C – pH is low, Co2 is high, Bicarb is high and attempting to correct
the problem (but has not completely helped) so this is partially
compensated respiratory acidosis

5. B – pH is high, Co2 is low, Bicarb is normal and not attempting
to correct the problem so this is an uncompensated respiratory
alkalosis
6. D – pH is high, Bicarb is high, Co2 is high and attempting to
correct the problem (but has not completely helped) so this is a
partially compensated metabolic alkalosis
7. C – pH is low, Co2 is high, Bicarb is high and attempting to
correct the problem (but has not completely helped) so this is a
partially compensated respiratory acidosis.

Arterial Blood Gas (ABG)Procedure and Interpretation \Mohammad Al-me`ani. , MSN, RN.

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