Question

Whats the difference in the causes and compensation for respiratory and metabolic acidosis? Which system causes each and which system will compensate?

Answer 1

Respiratory Acidosis:

Reduced rate of respiration Increased amounts of C02 in the body (INCREASED HC03-)

The increase in H+ ions reduces pH = MORE ACIDIC

Can occur in emphysema, asthma, pneumonia, Respiratory Centre Depression

NM Disorders, Airway Obstruction, Parenchymal Diseases

Metabolic Acidosis

High amounts of H+ ions therefore increased acidity (not due to respiratory condition)

Occurs in ketoacidosis, certain kidney diseases, diarrhea

Symptoms - Headaches, palpatations. abdominal pain, muscle weakness, kussmaul's breathing

6 Steps to ABG Analysis

Is the pH normal?

Is the C02 normal?

Is the HC03 normal?

Match the C02 or HC03 with the pH

Does the C02 or HC03 go the opposite direction?

Are the p02 and 02 sat. normal?

Normal Values

pH	7.35-7.45
CO2	35-45
P02	80-100
Hco3	22-26
02 Sat.	95-100%

Value	i Value	Î Value
pH	Acidosis	Alkalosis
CO2	Alkalosis	Acidosis
P02	Hypoxemia	02 therapy
HC03	Acidosis	Alkalosis
Sa02	Hypoxemia	—

Magnitude of metabolic component

Measures total body bases

Hemoglobin

Cl-, P04, S04

Albumin

Normal +2 to -2

In a metabolic disorder with appropriate compensation, the PaC02 (mmHg) is approximately the same as the first two digits of the pH after the decimal point.

A primary metabolic disorder will result in respiratory compensation.

Compensation How fast does it occur?
	Timing of peak compensation
Respiratory compensation for a primary metabolic disorder	1 - 24 hrs
Metabolic compensation for a primary respiratory disorder	12 hrs -5 days?

   
ALTERNTIVE TO CALCULATING COMPENSATON Respiratory Acidosis
Acute ----[HC03~] 1 1 mEq/L for each 10mmHg PCOj is above 40 mmHg  

Chronic------ [HC03~] 1 4mEq/L for each lOmmHg PCO2 is above 40 mmHg

Acid-Base Disorder	Mechanism of Compensation
Metabolic Acidosis (decrease HCO3 - decrease pH)	Increased minute ventilation (decrease PCO2 increase pH)
Respiratory Acidosis Increase PCO2 decrease PH	increase Reabsorption of HC03- and increase Excretion of H+ by the kidneys increase HCO3 -increase PH)