Acid Base disturbances Flashcards
Describe the pH, CO2 and bicarbonate in metabolic acidosis
pH: Low
CO2: Low (compensated)
HCO3: Low
Describe the pH, CO2 and bicarbonate in metabolic alkalosis
pH: High
CO2: High (compensated)
HCO3: High
Describe the pH, CO2 and bicarbonate in respiratory acidosis
pH: Low
CO2: High
HCO3: High (compensated)
Describe the pH, CO2 and bicarbonate in respiratory alkalosis
pH: High
CO2: Low
HCO3: Low (compensated)
What acronym can be used to interpret an ABG and determine whether the cause is metabolic or respiratory?
ROME Respiratory Opposite Metabolic Equal
What is meant by “respiratory opposite” in ROME?
Direction of pH change is opposite to direction of CO2 change
E.g. respiratory acidosis= low pH, high PaCO2
What is meant by “metabolic equal” in ROME?
pH change goes in same direction as CO2 change
What is the mechanism causing respiratory acidosis?
Alveolar hypoventilation
CO2 retention
What is the mechanism causing respiratory alkalosis?
Increase RR or tidal volume
Alveolar hyperventilation
CO2 washout
What is the mechanism causing metabolic acidosis?
Increased ingestion/ production of H+
Increased loss of HCO3
What is the mechanism causing metabolic acidosis?
Increased ingestion/ production of HCO3
Increased loss of H+
List 4 types of causes of respiratory acidosis
Airway obstruction: COPD
Acute lung disease: Pneumonia
Respiratory muscle weakness: Myasthenia Gravis
CNS Depression: Head traum
List 4 types of causes of respiratory alkalosis
Pain, anxiety, panic attacks
Pregnancy
Hypoxemia: Altitude
Pulmonary disease e.g. PE
What are the 2 types of metabolic acidosis?
High anion gap metabolic acidosis
Normal anion gap metabolic acidosis
What are the 2 types of metabolic alkalosis?
Chloride responsive
Chloride resistant
List 4 causes of high anion gap metabolic acidosis
Lactic acidosis: metformin use
Ketoacidosis: DM
Renal insufficiency
Iron tablets
List 4 causes of normal anion gap metabolic acidosis
Renal tubular acidosis
GI loss of HCO3: diarrhoea
Hyperchloremia
Addisons disease
List 3 causes of Chloride responsive metabolic alkalosis
Vomiting
Hypovolemia
Loop + thiazide diuretics
List 2 causes of Chloride resistant metabolic alkalosis
Hyperaldosteronism
Cushings
Describe compensation in metabolic disorders
Rapid compensation in minutes due to change in minute ventilation
Describe compensation in respiratory disorders
Slow compensation over hours/ days due to change in urine pH
What is a high anion gap indicative of?
Metabolic acidosis
