Arterial Blood Gasses

How are arterial blood gasses drawn?

From an indwelling arterial catheter

- Can be drawn rapidly and results in minutes

5 Arterial Blood Gasses

1. pH

2. PaCO2

3. HCO3

4. PaO25. O2 Sat (SaO2)

Normal pH Value

7.35-7.45

PaCO2

Partial pressure of carbon dioxide dissolved in arterial blood

What is PaCO2 influenced by?

Pulmonary function

Normal PaCO2 value?

37-43 mmHg

HCO3

Amount of bicarbonate or alkaline substance dissolved in blood

What is HCO3 influenced by?

Metabolic changes

Normal HCO3 Value

22-26 mmHg/L

PaO2

Partial pressure of oxygen dissolved in arterial blood

Normal PaO2 Level

80-95 mmHg

SaO2

Oxyhemoglobin saturation % of oxygen carried by hemoglobin

Normal SaO2 Value

95-85%

Is SaO2 or SpO2 more specific?

SaO2

- SpO2 is pulse ox

What ABG value do you look at first? Second?

- First examine pH

- Second note PaCO2

pH < 7.35

Acidosis

pH > 7.45

Alkalosis

CO2 and pH are ___ related?

Inversely

- High PaCO2 means low pH = Respiratory acidosis

- Low PaCO2 means high pH = Respiratory alkalosis

If the PaCO2 is normal and pH is not normal, look at ___ because the problem is ___?

HCO3, metabolic

Respiratory Acidosis

Lungs cannot remove all of the CO2 the body produces

- Blood is too acidic

Respiratory Alkalosis

Marked by low levels of Co2 in the blood d/t breathing excessively

- Blood is too basic

High HCO3 and pH = ___

Metabolic alkalosis

Low HCO3 and pH = ___

Metabolic Acidosis

Metabolic Acidosis

Caused by too much acid in body fluids

Metabolic Alkalosis

Caused by too much bicarbonate in the blood

- Blood becomes basic

ABG Charting Order

pH/CO2/PaCO2/HCO3

Low pH and High PCO2

Respiratory acidosis

Low pH and High HCO3

Metabolic Acidosis

High pH and Low PCO2

Respiratory alkalosis

High pH and High HCO3

Metabolic alkalosis