Arterial Blood Gases

Made Easy

Prepared by:

Rafiq SulemanBScN

Purpose of ABGPurpose of ABG Assess degree to which

LungsLungs are able to provide adequate O2 & remove

CO2 and

KidneysKidneys are able to reabsorb or excrete HCO3 .Feb 1st, 2014.2 Rafiq Suleman BScN

You Must Know What is Normal to be Able to Know What is Abnormal

pH = 7.35 to 7.45

PaC02 = 35 to 45 mm Hg

PaO2 = 80 to 100 mm Hg

HCO3 = 22 – 26 mEq/l Feb 1st, 2014.3 Rafiq Suleman BScN

What You Must Look At To Interpret ABGs

Feb 1st, 2014.4 Rafiq Suleman BScN

Look at Your pH

Is it normal?

Is it high ?

Is it low?

Feb 1st, 2014.5 Rafiq Suleman BScN

ExamplespH = 7.36

pH = 7.23

pH = 7.47

A high pH indicates alkalosis.

A low pH indicates acidosis.Feb 1st, 2014.6 Rafiq Suleman BScN

Look at Your PaCO2

Is it normal ?

Is it high ?

Is it low ?

This is the respiratoryrespiratory component.

An abnormality in the PaCO2 will

indicate

a respiratory problem.Feb 1st, 2014.7 Rafiq Suleman BScN

ExamplesPaCO2 = 40 mm Hg

PaCO2 = 23 mm Hg

PaCO2 = 48 mm Hg

A high PaCO2 indicates acidity.

A low PaCO2 indicates alkalosis. Feb 1st, 2014.8 Rafiq Suleman BScN

PaCO2

Lungs will increase or decrease

ventilation to remove the appropriate

amount of CO2 .

Lung compensation begins quickly.

Feb 1st, 2014.9 Rafiq Suleman BScN

Now Look at Your HCO3

Is it normal ?

Is it high ?

Is it low ?

This is the metabolicmetabolic component.An abnormality in the HCO3 indicates a

metabolic problem.Feb 1st, 2014.10 Rafiq Suleman BScN

Examples

HCO3 = 25 mEq/l

HCO3 = 19 mEq/l

HCO3 = 32 mEq/l

A low HCO3 indicates acidity.

A high HCO3 indicates alkalosis. Feb 1st, 2014.11 Rafiq Suleman BScN

HCO3

The kidneys excrete Hydrogen

(acid) & retain bicarbonate (base) to

help maintain pH.

Renal compensation is slow.

Feb 1st, 2014.12 Rafiq Suleman BScN

Let’s Look at the 4 Situations that Can Occur

Feb 1st, 2014.13 Rafiq Suleman BScN

Acidosis

Develops when:

Excess accumulation of acid

Decreased amount of alkali.

Can be respiratory or metabolic.

Feb 1st, 2014.14 Rafiq Suleman BScN

Metabolic AcidosisABGs:

Low pH (below 7.35).

Decreased HCO3 (below 22)

PaCO2 will be normal.

Remember both the pH & HCORemember both the pH & HCO33 will be low. will be low.  Feb 1st, 2014.15 Rafiq Suleman BScN

Metabolic AcidosisCaused by too much acid in the body or loss

of bicarbonate.

Diarrhea (loss of HCO3).

Diabetic ketoacidosis.

Renal failure.

Feb 1st, 2014.16 Rafiq Suleman BScN

Respiratory AcidosisABGs:

Low pH (below 7.35)

Increased PaCO2 (above 45)

HCO3 will be normal.

Remember the pH will be low & PaCORemember the pH will be low & PaCO22 will be will be

elevated (opposite).elevated (opposite).Feb 1st, 2014.17 Rafiq Suleman BScN

Respiratory AcidosisCaused by acid buildup due to lungs not

eliminating CO2 .

Anything that decreased. respirations can cause

respiratory acidosis.

Chronic respiratory disease.

CNS depression.Feb 1st, 2014.18 Rafiq Suleman BScN

Alkalosis

Develops when:

Excess accumulation of bicarbonate.

Loss of acid.

Feb 1st, 2014.19 Rafiq Suleman BScN

Metabolic AlkalosisABGs:

Increase in pH (greater than 7.45)

Increased HCO3 (greater than 26)

PaCO2 will be normal.

Remember both the pH & the HCORemember both the pH & the HCO33 will be elevated will be elevated.

Feb 1st, 2014.20 Rafiq Suleman BScN

Metabolic Alkalosis

Loss of acid or increase in HCO3

Vomiting or NG drainage

(loss of Hydrogen).

Excessive use of antacids.Feb 1st, 2014.21 Rafiq Suleman BScN

Respiratory AlkalosisABGs:

Increase in pH (greater than 7.45)

Decrease in PaCO2 (less than 35)

HCO3 will be normal.

Remember the pH will be high & PaCORemember the pH will be high & PaCO22 will be low will be low

(opposite).(opposite).

Feb 1st, 2014.22 Rafiq Suleman BScN

Respiratory Alkalosis

Caused by too much CO2 being

excreted

by the lungs.

Hyperventilation.

Feb 1st, 2014.23 Rafiq Suleman BScN

Interpreting ABGs

Feb 1st, 2014.24 Rafiq Suleman BScN

1st Step Look at pH

Is it normal (7.35 to 7.45)

Does it reflect acidosis ( less than 7.35).

Does it reflect alkalosis (greater than 7.45).

Label accordingly. Feb 1st, 2014.25 Rafiq Suleman BScN

Next Look at PaCO2

This is the respiratory component.

Is it normal.

Does it reflect alkalosis (less than 35).

Does it reflect acidosis (greater than 45).

Label accordingly.Feb 1st, 2014.26 Rafiq Suleman BScN

Next Look at the HCO3

This is the metabolic component

Is it normal.

Does it reflect acidosis (less than 22).

Does it reflect alkalosis (greater than 26).

Label accordingly.Feb 1st, 2014.27 Rafiq Suleman BScN

Let’s Put It All

Together

Feb 1st, 2014.28 Rafiq Suleman BScN

ProblemspH of 7.33

PaCO2 of 40 mmHg

HCO3 of 20 mEq/L

What does this indicate

Break it downFeb 1st, 2014.29 Rafiq Suleman BScN

pH = Acidosis

PaCO2 = Normal

HCO3 = Acidosis

An abnormal HCO3 indicates a metabolic

problem.Feb 1st, 2014.30 Rafiq Suleman BScN

Metabolic Acidosis

Way to go!!

Feb 1st, 2014.31 Rafiq Suleman BScN

ProblempH of 7.59

PaCO2 of 29 mm Hg

HCO3 of 24mEq/L

What does this indicate

Break it downFeb 1st, 2014.32 Rafiq Suleman BScN

pH = Alkalosis

PaCO2 = Alkalosis

HCO3 = Normal

An abnormal PaCO2 indicates a respiratory

problem.Feb 1st, 2014.33 Rafiq Suleman BScN

Respiratory Alkalosis

Great Job!!

Feb 1st, 2014.34 Rafiq Suleman BScN

ProblempH of 7.25

PaCO2 of 61 mmHg

HCO3 of 26 mEq/L

What does this indicate

Break it downFeb 1st, 2014.35 Rafiq Suleman BScN

pH = Acidosis

PaCO2 = Acidosis

HCO3 = Normal

An abnormal PaCO2 indicates a respiratory

problem.Feb 1st, 2014.36 Rafiq Suleman BScN

Respiratory Acidosis

You are doing a

great job !!

Feb 1st, 2014.37 Rafiq Suleman BScN

ProblempH of 7.51

PaCO2 of 44mmHg

HCO3 of 56

What does this indicate

Break it downFeb 1st, 2014.38 Rafiq Suleman BScN

pH = Alkalosis

PaCO2 = Normal

HCO3 = Alkalosis

An abnormal HCO3 indicates a metabolic

problem.Feb 1st, 2014.39 Rafiq Suleman BScN

Metabolic Alkalosis

You have become an ABG pro!!

Feb 1st, 2014.40 Rafiq Suleman BScN

You Are Doing Great

Feb 1st, 2014.41 Rafiq Suleman BScN

Compensation

Occurs as the body begins to correct the acid

base imbalance

pH will be normal or near normal if total

compensation

pH will be abnormal if partial compensationFeb 1st, 2014.42 Rafiq Suleman BScN

Compensation

Both the PaCo2 & HCO3 will be abnormal

Respiratory imbalances are compensated

for by the renal system

Metabolic imbalances are compensated for

by the respiratory system Feb 1st, 2014.43 Rafiq Suleman BScN

ExamplepH of 7.27

PaCO2 of 27 mm Hg

HCO3 of 10 mEq/l

Note that both the PaCO2 & the HCO3 are

low.Feb 1st, 2014.44 Rafiq Suleman BScN

Let’s Break it DownLow pH = Acidosis

Low PaCO2 = Alkalosis

Low HCO3 = Acidosis

HCO3 corresponds with the pH

This is a metabolic problem

Metabolic acidosis with partial compensation.Feb 1st, 2014.45 Rafiq Suleman BScN

ProblemspH of 7.52

PaCO2 of 47 mmHg

HCO3 of 36 mEq/L

What does this indicate

Break it downFeb 1st, 2014.46 Rafiq Suleman BScN

pH = Alkalosis

PaCO2 = Acidosis

HCO3 = Alkalosis

Which two go together?

Feb 1st, 2014.47 Rafiq Suleman BScN

Metabolic Alkalosis with Partial Compensation

You are doing great!!

Feb 1st, 2014.48 Rafiq Suleman BScN

ProblemspH of 7.45

PaCO2 of 50 mmHg

HCO3 of 33 mEq/L

What does this indicate

Break it downFeb 1st, 2014.49 Rafiq Suleman BScN

pH = Normal

PaCO2 = Acidosis

HCO3 = Alkalosis

Your pH leans toward the alkalosis side.

Feb 1st, 2014.50 Rafiq Suleman BScN

Fully Compensated Metabolic Alkalosis

You have done great!!

Feb 1st, 2014.51 Rafiq Suleman BScN

Feb 1st, 2014.52 Rafiq Suleman BScN