ABG + Umbilical Gases

Question 1

ABG Normal Values

Answer 1

pH: 7.35-7.45
CO2: 35-45
pO2: 80-90* age dependent
HCO3: 25+/- 3

Question 2

ABG Interpretation Steps

Answer 2

1. pH Alkalosis or Acidosis?
2. Examine CO2 and HCO3, O2. What is the primary issue (resp vs metabolic)?
3. Check compensation
4. Check for Anion Gap
   = Na - (cl + HCO3)
   Normal <12
5. If anion gap, check delta-delta (rise in anion gap accounted for by drop in bicarb?)
6. If AGMA, check for osmolar gap (>10)

Question 3

Metabolic compensation for Respiratory Issue

Answer 3

For every CO2 change by 10, bicarb changes by:
Acute Acidosis - 1
Chronic Acidosis - 4
Acute Alkalosis - 2
Chronic Alkalosis - 5

Question 4

Respiratory Compensation for Metabolic Issue

Answer 4

for every change in bicarb, CO2 changes by:

Met Acid: 1:1
Met Alk: 1:0.7

Question 5

How to Calculate Osmolar Gap

Answer 5

Normal is <10

OG = osmolality - calculated

calculated (osmolarity)
= 2(Na) + Glucose + Urea

(in mmol/dL)

Question 6

Acidemia in Umbilical Gas

Answer 6

Arterial pH <7.2 = acidemia

<7.0 or base deficit > 12 = asphyxiation