Acid / Base

Table of contents

Basics
Buffer system

Basics

	Respiratory acidosis	Respiratory alkalosis	Metabolic acidosis	Metabolic alkalosis
pH	<	>	<	>
PCO2	Up	Down	Down (compensation)	Up (compensation)
HCO3-	Up (compensation)	Down (compensation)	Down	Up
Mechanism	Hypoventilation -> $\ce{CO2}$ retention	Increased RR and/or Vt -> Hyperventilation -> $\ce{CO2}$ washout	Increased production/ingestion of $\ce{H+}$ or loss of $\ce{HCO3-}$	Loss of $\ce{H+}$ or increased production/ingestion of $\ce{HCO3-}$
Common causes	- Airway obstruction (e.g. choking, COPD, asthma) - CNS Depression (drug toxicity, post-ictal, trauma) - Acute lung problem (e.g. Pneumonia, pulmonary oedema)	- Pain - Anxiety/Panic Attack - Pregnancy - Sepsis -CCF	- Ketoacidosis - Addisons Disease (adrenal insufficency) - Diarrhoea	- Vomiting - Diuretics - Hypovolemia

Note. From Kasper DL, Fauci AS, Hauser SL, Longo DL, Lameson JL, Loscalzo J. Harrison’s Principles of Internal Medicine. New York, NY: McGraw-Hill Education; 2015

Buffer system

\ce{CO2 + H2O <-> H2CO3 <-> HCO3- + H+}