Volume depletion in adults

Outcome in volume depletion depends on its severity, the underlying clinical diagnosis, and the management of volume resuscitation. In hypovolaemic shock, when systolic blood pressure is <80 mmHg and signs of organ ischaemia are present, inadequate volume resuscitation will lead to poor outcomes. Furthermore, if the patient presents late in their clinical course, it may be extremely difficult to replace the volume deficit adequately. At extremes of age, clinically severe volume depletion occurs quickly and must be addressed early. In most situations, satisfactory management is achievable as long as the cause of volume depletion is addressed and the appropriate fluid used for replenishment.

Haemorrhage

The prognosis depends entirely on the underlying cause of bleeding. A ruptured abdominal aortic aneurysm is often catastrophic, and patients can be critically ill. In contrast, with a bleeding gastric ulcer, if volume loss is appropriately managed and the bleeding stopped in a timely fashion, the outcome is generally favourable.

Gastrointestinal losses

Generally, these are due to self-limiting conditions such as viral gastroenteritis. However, the rate and duration of fluid loss determine the severity of volume depletion at presentation. Most patients will do well, but diarrhoeal illness, particularly in developing countries, is a significant cause of morbidity and mortality. In infants and older people, only small amounts of volume loss may have large clinical consequences, so outcomes can be poor without adequate resuscitation or with a delay in clinical evaluation.

Renal losses

This is usually manageable with the appropriate choice of replacement fluid, as long as the underlying reason for renal fluid loss can be treated. If over-use of diuretics is the cause, then the dose can be adjusted, and if due to an intrinsic renal disease, the appropriate replacement of abnormal electrolytes must be taken into consideration. It is rare for renal fluid losses alone to cause severe hypovolaemia unless a patient has multiple comorbid conditions and the volume depletion leads to acute kidney injury or organ ischaemia.

Third-space sequestration

Prognosis depends very much on the underlying disease that is causing the sequestration.

Respiratory fluid losses

This is a rare cause of volume depletion, and long-term prognosis will depend on management of the underlying cause. However, appropriate fluid resuscitation is generally possible in the short term.