Book contents
- Frontmatter
- Contents
- List of Abbreviations
- Acknowledgements
- Abdominal Trauma: Investigations
- Accessing the Thorax
- Acid-Base
- Acute Renal Failure (see also table in ‘Low urine output’)
- Acute Respiratory Distress Syndrome (ARDS)
- Agitation and Sedation
- Airway Management
- Analgesia
- Aortic Dissection
- Atelectasis
- Blood Pressure Monitoring
- Blood Products
- Blood Transfusion
- Brainstem Death and Organ Donation
- Bronchiectasis
- Burns
- Calcium Balance
- Cardiac Assessment
- Cardiogenic Shock
- Central Line Insertion
- Chronic Renal Failure
- Coagulation Defects
- Disseminated Intravascular Coagulation (DIC)
- ECG I – Basic Concepts
- ECG II – Rate and Rhythm Disturbances
- Endotracheal Intubation
- Enteral Nutrition
- Extubation and Weaning
- Fat Embolism Syndrome
- Flail Chest
- Fluid Therapy
- Haemorrhagic Shock
- Head Injury I – Physiology
- Head Injury II – Pathophysiology
- Head Injury III – Principles of Management
- Inotropes and Circulatory Support
- ITU Admission Criteria
- Jugular Venous Pulse (JVP)
- Lactic Acidosis
- Low Urine Output State
- Magnesium Balance
- Mechanical Ventilatory Support
- Metabolic Acidosis (see also ‘Acid-base’ and and ‘Lactic acidosis’)
- Metabolic Alkalosis
- Nutrition: Basic Concepts (see also parenteral nutrition & TPN)
- Oxygen: Basic Physiology
- Oxygen Therapy
- Parenteral Nutrition (TPN)
- Pneumonia
- Pneumothorax
- Potassium Balance
- Pulmonary Artery Catheter (see also ‘Central line insertion’)
- Pulmonary Thromboembolism
- Pulse Oximetry
- Renal Replacement Therapy
- Respiratory Assessment
- Respiratory Failure (see also ‘Oxygen therapy’)
- Rhabdomyolysis
- Septic Shock and Multi-Organ Failure
- Sodium and Water Balance
- Spinal Injury
- Systemic Response to Trauma
- Tracheostomy
- Transfer of the Critically Ill
- Tube Thoracostomy (Chest Drain)
Potassium Balance
- Frontmatter
- Contents
- List of Abbreviations
- Acknowledgements
- Abdominal Trauma: Investigations
- Accessing the Thorax
- Acid-Base
- Acute Renal Failure (see also table in ‘Low urine output’)
- Acute Respiratory Distress Syndrome (ARDS)
- Agitation and Sedation
- Airway Management
- Analgesia
- Aortic Dissection
- Atelectasis
- Blood Pressure Monitoring
- Blood Products
- Blood Transfusion
- Brainstem Death and Organ Donation
- Bronchiectasis
- Burns
- Calcium Balance
- Cardiac Assessment
- Cardiogenic Shock
- Central Line Insertion
- Chronic Renal Failure
- Coagulation Defects
- Disseminated Intravascular Coagulation (DIC)
- ECG I – Basic Concepts
- ECG II – Rate and Rhythm Disturbances
- Endotracheal Intubation
- Enteral Nutrition
- Extubation and Weaning
- Fat Embolism Syndrome
- Flail Chest
- Fluid Therapy
- Haemorrhagic Shock
- Head Injury I – Physiology
- Head Injury II – Pathophysiology
- Head Injury III – Principles of Management
- Inotropes and Circulatory Support
- ITU Admission Criteria
- Jugular Venous Pulse (JVP)
- Lactic Acidosis
- Low Urine Output State
- Magnesium Balance
- Mechanical Ventilatory Support
- Metabolic Acidosis (see also ‘Acid-base’ and and ‘Lactic acidosis’)
- Metabolic Alkalosis
- Nutrition: Basic Concepts (see also parenteral nutrition & TPN)
- Oxygen: Basic Physiology
- Oxygen Therapy
- Parenteral Nutrition (TPN)
- Pneumonia
- Pneumothorax
- Potassium Balance
- Pulmonary Artery Catheter (see also ‘Central line insertion’)
- Pulmonary Thromboembolism
- Pulse Oximetry
- Renal Replacement Therapy
- Respiratory Assessment
- Respiratory Failure (see also ‘Oxygen therapy’)
- Rhabdomyolysis
- Septic Shock and Multi-Organ Failure
- Sodium and Water Balance
- Spinal Injury
- Systemic Response to Trauma
- Tracheostomy
- Transfer of the Critically Ill
- Tube Thoracostomy (Chest Drain)
Summary
What is the normal level of the serum potassium?
3.5–5.0 mmol/l.
What is the distribution of potassium in the body?
98% of the total body potassium is intracellular. The intracellular concentration is ∼150 mmol/l compared to ∼4 mmol/l in the serum.
How is potassium regulated?
There are a number of influential factors on serum potassium
Dietary potassium: the ‘Western’ diet may contain 20–100 mmol of potassium daily
Aldosterone: this is a mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex. It stimulates sodium reabsorption in the distal convoluted tubule and cortical collecting duct through an active exchange with potassium, whose excretion is therefore promoted
Acid-Base balance: potassium and H+ are exchanged at the cell membrane, so that excess of one or the other leads to increased exchange. Thus, acidosis leads to hyperkalaemia and vice versa. Similarly, alkalosis can lead to hypokalaemia and vice versa. This also occurs at the kidney where reabsorption of one causes excretion of the other
Tubular fluid flow rate: increased flow rate promotes potassium secretion. This is one method by which some diuretics may cause hypokalaemia
Insulin: this stimulates potassium uptake into cells, reducing the serum level
What are the causes of hyperkalaemia?
Artefact: haemolysis in the blood bottle
Excess oral or i.v. administration
Redistribution:
Between the ICF and ECF due to injury: intravascular haemolysis, burns, tissue necrosis
Reduced cellular uptake: insulin deficiency, acidosis
Decreased excretion:
Renal origin: renal failure, potassium-sparing diuretics
Adrenal origin: Addison's disease
Mineralocorticoid resistance: systemic lupus erythematosus, chronic interstitial nephritis
- Type
- Chapter
- Information
- Surgical Critical Care Vivas , pp. 180 - 182Publisher: Cambridge University PressPrint publication year: 2002