ABG Interpretation midterm study

What is acidaemia [pH value, H+ ions]?

pH < 7.35

Increase in H+ ions

What is alkalaemia [pH value, H+ ions]?

pH > 7.45

Decrease in H+ ions

PaCO2 is regulated by what organ?

Lungs

Acidemia and a raised PaCO2 indicates which state?

Primary respiratory acidosis

Alkalemia and a decreased PaCO2 indicates which state?

Primary respiratory alkalosis

Bicarbonate is regulated by what organ?

Kidneys

Low bicarbonate levels and base excess < -2mmol/L indicate what?

Metabolic acidosis

Alkalosis and High bicarbonate levels indicate what?

Metabolic Alkalosis

Acidemia and low bicarbonate indicate what state?

Primary metabolic acidosis

Alkalosis and high bicarbonate indicate what state?

Primary metabolic alkalosis

What is the aim of compensation?

maintain homeostasis

If pH returns to normal, what type of compensation is this?

Complete compensation

If compensation has begun but, pH remains abnormal, what type of compensation is this?

Partial compensation

low pH (acid) + low HCO3 (acid)

metabolic acidosis

low pH (acid) + high PaCO2 (acid)

respiratory acidosis

high pH (base) + high HCO3

metabolic alkalosis

high pH (base) + low PaCO2 (base)

respiratory alkalosis

normal pH + both HCO3 and PaCO2 are abnormal, is what type of compensation?

full compensation

abnormal pH + both HCO3 and PaCO2 are abnormal, is what type of compensation?

partial compensation

abnormal pH + one abnormal value for either HCO3 or PaCO2 + one normal value for either HCO3 or PaCO2, is what type of compensation

uncompensated compensation

What would pH, PaCO2 and HCO3- look like in respiratory acidosis, uncompensated?

Low pH

High PaCO2

Normal HCO3-

What would pH, PaCO2 and HCO3- look like in respiratory alkalosis, uncompensated?

High pH

Low PaCO2

Normal HCO3-

What would pH, PaCO2 and HCO3- look like in metabolic acidosis, uncompensated?

Low pH

Normal PaCO2

Low HCO3-

What would pH, PaCO2 and HCO3- look like in metabolic alkalosis, uncompensated?

High pH

Normal PaCO2

High HCO3-

causes of respiratory acidosis

drugs/narcotics; neuromuscular disease; morbid obesity; severe kyphoscoliosis; chronic obstructive pulmonary disease (COPD); sarcoidosis, pulmonary fibrosis

causes of respiratory alkalosis

hyperventilation; anxiety; fever; sepsis; salicylate overdose; pulmonary embolism; pneumonia; acute bronchial asthma; aggressive mechanical ventilation

causes of metabolic acidosis

ketoacidosis; poison; renal failure; potassium sparing diuretics; diarrhea; excess intake of ammonium chloride

causes of metabolic alkalosis

excessive vomiting; diuretics; hypokalemia; Cushing syndrome; milk-alkali syndrome; excessive antacid use

What is an indicator of the adequacy of alveolar ventilation?

PaCO2

High PaCO2 reflects what type of breathing?

hypoventilation or inadequate ventilation

Low PaCO2 indicates what type of breathing?

hyperventilation or excessive ventilation

What ABG numbers indicated Mixed acidosis

A combination of low pH with either low PaCO2 (respiratory acidosis) or low HCO3- (metabolic acidosis)

What ABG numbers indicated mixed alkalosis?

A combination of high pH with either high PaCO2 (respiratory alkalosis) or high HCO3- (metabolic alkalosis)

ABG: 7.27 pH; 56mmHg PaCO2; 70mmHg PaO2; 26mmol/L HCO3; 140mmol/L Na+; 4mmol/L K+; 105mmol/L Cl-. 30 yo male, breathing room air, low RR, bradycardia, hypotension, unconscious.

pH: acidosis

PaCO2: acidosis

HCO3: normal

indicates respiratory acidosis, no compensation w/

mild hypoxemia

dx: drug overdose/ possible respiratory center depression.

ABG: 7.25 pH; 20mmHg PaCO2; 90mmHg PaO2; 10mmol/L HCO3; 140mmol/L Na+; 4mmol/L K+; 105mmol/L Cl-. 55yo female, hx: diabetes, coma, gasping, deep respirations on room air.

pH: acidosis

PaCO2: alkalotic

HCO3: acidosis

indicates metabolic acidosis with partial compensation

no hypoxemia

high anion gap (25)

dx: ketoacidosis, diabetic coma