The Measurement of pH
Basic foundations of acid-base chemistry for the intensivist
The Arrhenius definition of acids and bases
The Brønsted-Lowry definition of acids and bases
Lewis' definition, and the modern concept of acids and bases
The hydrogen ion as a convenient narrative device
The Sorensen definition of pH as hydrogen ion concentration
The modern concept of pH
The gold standard of pH measurement
History of the glass electrode
Measurement of pH in a modern ABG analyser
Neutrality and the influence of temperature and pressure on pH
Alpha-stat and pH-stat models of blood gas interpretation
The Measurement of the Partial Pressures of Dissolved Gases
Fundamental gas laws relevant to critical care medicine
Partial pressure and the solubility of gases in biological systems
The alveolar gas equation
Measurement of dissolved pO2 by electrolysis of dissolved oxygen
Principles of pO2 measurement with the Clark electrode
Principles of measuring pCO2 with the Severinghaus electrode
Absorption Spectroscopy of Haemoglobin Species
Absorption spectroscopy of haemoglobin species
Concentration of total haemoglobin in the ABG sample
Haematocrit: erythrocyte volume as fraction of total volume
Methaemoglobin measurement by the blood gas analyser
Biological properties of methaemoglobin
Causes and mechanisms of methaemoglobinaemia
Spectrophotometry of carboxyhaemoglobin
Assessment of Gas Transport and Gas Exchange
Measurement of oxygen saturation by the blood gas analyser
Fraction of oxygenated haemoglobin
The oxygen - carrying capacity of whole blood
The oxyhaemoglobin dissociation curve
Factors which influence the affinity of haemoglobin for oxygen
The p50 value of a blood gas sample
The idealised p50 value for a standard set of conditions
Oxygen tension - based indices of oxygenation
The shunt equation and content - based indices of oxygenation
Measurement of Electrolyte and Metabolyte Concentration
The ion-sensitive electrode chain in the blood gas analyser
Ion-selective electrode membranes
The potassium-sensitive electrode in the blood gas analyser
The sodium-sensitive electrode in the blood gas analyser
The calcium-sensitive electrode in the blood gas analyser
Factors influencing the concentration of ionised calcium
Correction of ionised calcium for pH
The chloride-sensitive electrode in the blood gas analyser
Principles of amperometric measurement
Amperometric measurement of glucose
Amperometric measurement of lactate
Assessment of Acid-Base Disturbance and Buffering
The actual bicarbonate value
The standard bicarbonate value
The actual base excess
Standard base excess
Assessment of compensation: Boston and Copenhagen methods
Stewart's approach to analysis of acid-base disorders
Practical Interpretation of Blood Gas Data
The officical diagnostic sequence for blood gas interpretation
A systematic approach to the interpretation of blood gas data
Summary of equations used for blood gas interpretation
The anion gap; its merits and demerits
Delta gap and delta ratio
Central Venous and Mixed Venous Blood Gases
The relationship of venous oxygenation and cellular metabolism
Practical use of central and mixed venous blood gases
Case Studies in Respiratory Acidosis
Catastrophe in the sleep lab
Post-Operative Respiratory Failure
Difficult intubation with prolonged poor quality manual ventilation
Case Studies in High Anion Gap Metabolic Acidosis
Poisoning by an Unknown Substance
Ischaemic gut
Case Studies in Mixed Metabolic Acidosis
Septic shock resuscitated with normal saline
Exotic Blood Gas Scenarios
"That can't possibly be human arterial blood"