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Arterial Blood Gas Analysis

Presenter : dr. Nivedita R Shetty

dr. Rollando Erric Manibuy

Supervisor : dr. Tatang SpB-KBD, KIC

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What Is An ABG?pH [H+]

PCO2 Partial pressure

CO2

PO2 Partial pressure O2

HCO3 Bicarbonate

BE Base excess

SaO2 Oxygen Saturation

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The normal range

Desired Ranges pH - 7.35 - 7.45

PaCO2

- 35-45 mmHg

PaO2 - 80-100 mmHg

HCO3 - 21-27

O2sat - 95-100%

Base Excess - +/-2 mEq/L

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Why Order an ABG?

Helps in establishing a diagnosis

Helps guide treatment plan

Helps in ventilator management Improvement in acid/base management

allows for optimal function of medications

Acid/base status may alter electrolyte levels

critical to patient status/care

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From where is the sample

taken Radial artery

Femoral artery

Brachial artery

Dorsalis Pedis artery

Axillary artery

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Acid Base Balance

The body produces acids daily

15,000 mmol CO2

50-100 mEq Nonvolatile acids

The lungs and kidneys attempt to

maintain balance

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Acid Base Balance

Assessment of status via bicarbonate-carbon dioxide buffer system

CO2 + H2O H2CO3 HCO3- + H+

ph = 6.10 + log ([HCO3] / [0.03 x PCO2])

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The Terms

ACIDS

Acidosis Respiratory

CO2

Metabolic

HCO3

BASES

Alkalosis Respiratory

CO2

Metabolic

HCO3

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Respiratory Acidosis

ph, CO2,Ventilation

Causes

CNS depression

Pleural disease

COPD/ARDS

Musculoskeletal disorders

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Respiratory Acidosis

Acute vs Chronic

Acute - little kidney involvement. Buffering

via titration via Hb for example pH by 0.08 for 10mmHg in CO2

Chronic - Renal compensation viasynthesis and retention of HCO3 (Cl to

balance charges hypochloremia) pH by 0.03 for 10mmHg in CO2

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Respiratory Alkalosis

pH, CO2,Ventilation

CO2 HCO3 (Cl to balance charges

hyperchloremia) Causes

Intracerebral hemorrhage

Salicylate and Progesterone drug usage

Anxietylung compliance Cirrhosis of the liver

Sepsis

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Respiratory Alkalosis

Acute vs. Chronic

Acute - HCO3 by 2 mEq/L for every

10mmHg in PCO2 Chronic - Ratio increases to 4 mEq/L of

HCO3 for every 10mmHg in PCO2

Decreased bicarb reabsorption anddecreased ammonium excretion tonormalize pH

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Metabolic Acidosis

pH, HCO3

12-24 hours for complete activation of

respiratory compensation PCO2 by 1.2mmHg for every 1 mEq/LHCO3

The degree of compensation isassessed via the Winters Formula

PCO2 = 1.5(HCO3) +8 2

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Metabolic Alkalosis

pH, HCO3

PCO2 by 0.7 for every 1mEq/L in HCO3

Causes Vomiting

Diuretics

Chronic diarrhea

Hypokalemia

Renal Failure

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THANK YOU....