Volume depletion is characterised by a reduction in extracellular fluid volume that occurs when salt and fluid losses exceed intake on a sustained basis.
The most common aetiologies are haemorrhage, vomiting, diarrhoea, diuresis, or third-space sequestration.
A detailed history and physical examination are crucial in determining the aetiology.
Signs and symptoms may include some of the following: postural dizziness, fatigue, confusion, muscle cramps, chest pain, abdominal pain, postural hypotension, or tachycardia.
Clinical symptoms usually do not manifest until large fluid losses have occurred.
Without proper assessment and timely resuscitation, volume depletion can lead to circulatory collapse and shock.
May be accompanied by electrolyte disturbance or acid-base disturbance.
In most situations, isotonic crystalloid is the best initial treatment for volume depletion. Balanced crystalloids may be preferable to normal saline in critically ill patients in intensive care and are recommended in patients with sepsis or septic shock.
Volume depletion is a reduction in extracellular fluid volume that occurs when salt and fluid losses exceed intake on a sustained basis. It may result from renal losses (diuresis) or extrarenal losses (from the gastrointestinal tract, respiratory system, skin, fever, sepsis, or third-space sequestration). Without proper assessment and timely resuscitation, volume depletion can lead to circulatory collapse and shock.
Dehydration and volume depletion are not the same, although they can co-exist in the same patient at the same time. Although often used interchangeably, it is important to distinguish one from the other. Dehydration implies a total body water deficit, alone or in excess of sodium loss, with a subsequent increase in plasma tonicity that usually comes to clinical attention as hypernatraemia. This hypertonicity implies intracellular water contraction whereas volume depletion implies blood volume contraction. Symptoms of pure water loss arise from the effects of increased osmolality and reflect the cellular responses to hypertonicity: confusion, thirst, impaired sensorium, and, in more extreme cases, coma or seizures. By contrast, clinical symptoms of volume depletion are a result of the haemodynamic effects of the reduction in intravascular volume and usually do not involve neurological changes.
History and exam
Key diagnostic factors
- postural dizziness
- weight loss
- orthostatic hypotension
- postural tachycardia
- signs of shock
Other diagnostic factors
- decreased urine output
- high-volume gastrointestinal drainage
- poor oral intake
- severe sweating
- intestinal obstruction
- severe pancreatitis
- crush injuries
- intra-abdominal bleeding
- dry mucous membranes
- muscle cramps
- abdominal pain
- chest pain
- decreased skin turgor
- diuretic therapy
- chronic kidney disease
- older adult
- altered mental status
- high ambient temperature
1st investigations to order
- serum electrolytes
- blood glucose
- serum urea
- serum creatinine
- random urine sodium
- fractional excretion of sodium (FENa)
- random urine chloride
- random urine creatinine
- random urine osmolality
- rectal examination and faecal occult blood test
Investigations to consider
- urine urea/fractional excretion of urea (FE urea)
- arterial blood gases
- nasogastric lavage
- stool cultures
- abdominal ultrasound
- abdominal CT scan
- upper gastrointestinal endoscopy
- saliva osmolality
- point-of-care magnetic relaxometry
gastrointestinal non-haemorrhagic losses: vomiting and/or diarrhoea
pulmonary losses: bronchorrhoea or draining pleural effusion
sustained inadequate oral intake
- Heart failure
- Hepatorenal syndrome
- Surviving sepsis campaign: international guidelines for management of sepsis and septic shock
- Fluid therapy in neurointensive care patients
Diarrhoea in adultsMore Patient leaflets
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