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)
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Sodium and Water Balance
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)
Summary
What is the distribution of sodium in the body?
Sodium is the major extracellular cation of the body
50% is found in the extracellular fluid
45% is found in the bone
5% in the intracellular compartment
The vast majority (∼70%) is found in the readily exchangeable form.
What are the major physiological roles of sodium?
Because of the content of sodium in the body, it exerts significant osmotic forces, and so important for internal water balance between the intra and extracellular compartments. It also has a role in determining external water balance and the extracellular fluid volume. The other important role of sodium is in generating the action potential of excitable cells.
What is the daily sodium requirement?
The daily requirement is about 1 mmol/kg/day.
What is the normal plasma concentration?
The normal is 135–145 mmol/l.
Give a simple classification of the causes of hyponatraemia.
Water excess
Increased intake: polydipsia, iatrogenic, e.g. TURP syndrome, excess dextrose administration
Retention of water: SIADH
Retention of water and salt: nephrotic syndrome, cardiac and hepatic failure
Water loss (with even greater sodium loss)
Renal losses: diuretics, Addison's disease, relief of chronic urinary obstruction
Gut losses: diarrhoea, vomiting
Pseudohyponatraemia: in the presence of hyperlipidaemia
What is pseudohyponatraemia?
This is hyponatraemia that occurs as a peculiarity of the way in which the sodium concentration of the plasma is measured and expressed. In the presence of hyperlipidaemia or hyper–proteiaemia, the sodium concentration may be falsely low if it is expressed as the total volume of plasma, and not just the aqueous phase (which…
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- Surgical Critical Care Vivas , pp. 213 - 215Publisher: Cambridge University PressPrint publication year: 2002
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