arterial blood gases (3)

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Page 1: Arterial Blood Gases (3)

اللهم علمني ما ينفعني ( )وانفعني بما علمتني

الرحمن الله بسمالرحيم

Page 2: Arterial Blood Gases (3)

Arterial Blood GasesArterial Blood Gases

This article will help us to

1. Interpret arterial blood gases.

2 .Translate informations into effective action.

Page 3: Arterial Blood Gases (3)

IndicationsIndications

It is essential in evaluation of critical ill patient , giving an idea about his acid base balance and oxygenation . In a respiratory disturbance , it is a diagnostic assessment of the nature , severity and progress of the illness .

Page 4: Arterial Blood Gases (3)

TechniqueTechnique

•Choose vessels that have best collateral circulation.

•Puncture of a site where the artery is superficial .

•Radial artery is the best choice , if not accessible : dorsalis pedis , posterior tibial , brachial and femoral arteries .

Page 5: Arterial Blood Gases (3)

•Brachial and femoral arteries puncture are contraindicated in patients with abnormal haemostatic mechanism .

Page 6: Arterial Blood Gases (3)

PH 7.35 – 7.45

PaCO2 35 – 45 mmHg

PaO2 80-100 mmHg

HCO3 22 – 26mq / L

O2 saturation 95 – 100 %

Normal values of ABG,s

Page 7: Arterial Blood Gases (3)

Interpretation of ABG,sInterpretation of ABG,s

Does the patient have acidosis or alkalosis ?

If PH < 7. 35 acidosis

If PH > 7. 45 alkalosis

Page 8: Arterial Blood Gases (3)

Is acidosis / alkalosis respiratory or metabolic?

If PH and PaCO2 move in the same direction

If PH and PaCO2 move in the opposite direction it is primary respiratory acid - base disturbance.

it is primary metabolic acid – base disturbance .

Page 9: Arterial Blood Gases (3)

PH PaCO2

Metabolic acidosis

Metabolic alkalosis

Respiratory acidosis

Respiratory alkalosis

Page 10: Arterial Blood Gases (3)

Is the respiratory disorder is acute Is the respiratory disorder is acute ( uncompensated ) or chronic ( uncompensated ) or chronic ( compensated ) ?( compensated ) ?

•If PH is unaccepted it is acute.

•If PH is accepted it is chronic.

N.B accepted PH is from 7.30 to 7.50.

Page 11: Arterial Blood Gases (3)

Acid – Base Disorder Primary change Compensatory change

Respiratory acidosis PaCo2HCo3Respiratory acidosis

Respiratory alkalosis PaCo2HCo3

Metabolic acidosis HCo3 PaCo2

Metabolic alkalosis HCo3 PCo2

Page 12: Arterial Blood Gases (3)

Is the patient hypoxemic or not ?Is the patient hypoxemic or not ?

.If PaO2 between 80 – 100 mmHg , oxygenation is normal.

.If PaO2 is < 60 mmHg , hypoxic state is existing.

Page 13: Arterial Blood Gases (3)

* In respiratory disturbances : .If ABG,s show only that PaO2 is < 60 mmHg

Hypoxaemic ( type I ) Respiratory Failure .

.If PaO2 < 60 mmHg & PaCO2 > 45mmHg, Hypoxaemic , Hypercapnic ( type II )

Respiratory Failure.

Page 14: Arterial Blood Gases (3)

Indication for Critical Care Indication for Critical Care Unite admissionUnite admission

1. Persistent or worsening hypoxemia ( PaO2 < 50 mmHg ) .

2 .Severe or worsening hypercapnia ( PaCO2 > 70 mmHg ) .

3 .Severe or worsening respiratory acidosis ( PH < 7.30 ) .

Page 15: Arterial Blood Gases (3)

Measures to improve Measures to improve ventilation ventilation

1. Enhancing alveolar ventilation i.e treatment of the cause ( drug over dose / central hypoventilation / neuromuscular disease / airway obstruction ) .

2 .Decrease CO2 production -Bring fever down . -Avoid excessive nutritional calories.

Page 16: Arterial Blood Gases (3)

Measures to improve Measures to improve oxygenationoxygenation

1. O 2 supplementation

* RF type I nasal catheter / face mask .

* RF type II venturi mask “ controlled oxygen “ .

Page 17: Arterial Blood Gases (3)

2 .Treatment of the cause .

3 .Anaemic patients should be transfused to haemoglobin of 10 gm. %

Page 18: Arterial Blood Gases (3)

adequate delivery of oxygenated blood to tissues .

4. Hypotensive patients should be resuscitated to an adequate cardiac output to assure

Page 19: Arterial Blood Gases (3)

EXAMPLE 1EXAMPLE 1

PH 7.34 (academia )

Pa CO2 48 ( academia )

Pa O2 129 ( normal )

HCO3–

26 ( normal )

BE + 1 ( normal )

Sa O 2 99 % ( normal )

Interpretation

Respiratory acidosis , adequate oxygenation.

Page 20: Arterial Blood Gases (3)

EXAMPLE 2EXAMPLE 2

PH 7.40 ( normal )

Pa CO2 58 ( academia )

Pa O2 57 ( hypoxemia )

HCO3–

35 ( alkalemia )

BE + 9 ( alkalemia )

Sa O 2 89 % ( hypoxemia )

Interpretation

Respiratory acidosis with complete metabolic compensation and hypoxemia.

Page 21: Arterial Blood Gases (3)

EXAMPLE 3EXAMPLE 3

PH 7.29 (academia )

Pa CO2 40 ( normal )

Pa O2 192 ( normal )

HCO3–

19 (academia )

BE - 5.6 (academia )

Sa O 2 97.5 % ( normal )

Interpretation

Metabolic acidosis with no compensation , adequate oxygenation.

Page 22: Arterial Blood Gases (3)

EXAMPLE 4EXAMPLE 4

PH 7.37 ( normal )

Pa CO2 40 ( normal )

Pa O2 126 ( academia )

HCO3–

20 ( academia )

BE - 3.1 ( academia)

Sa O 2 98 % ( normal )

Interpretation

Fully compensated metabolic acidosis , adequate oxygenation.

Page 23: Arterial Blood Gases (3)