History and exam
Key diagnostic factors
common
postural dizziness
When haemorrhage is suspected, it has a sensitivity of 22% for moderate blood loss and 97% for severe blood loss.[2] The specificity is 98%.[2] This finding is less well established with volume depletion from other causes.[2] It can also be a sign of autonomic insufficiency, which is not volume depletion.
weight loss
A decrease from baseline weight.
orthostatic hypotension
Orthostatic hypotension is defined as a decrease of >20 mmHg in systolic blood pressure from supine to standing and/or a drop in diastolic pressure of >10 mmHg within 3 minutes of standing or head-up tilt from a supine position, although this may also occur in cases of autonomic insufficiency or from treatment with certain antihypertensive drugs.[2][20][21] In cases when the patient’s systolic BP is <90 mmHg, it is often not necessary and even dangerous to check for orthostatic vital signs.
postural tachycardia
An increase in pulse rate of >15 beats per minute indicates significant orthostatic changes.[22] An increase in pulse rate of >30 beats per minute from supine to standing has a sensitivity of 22% for moderate blood loss and 97% for severe blood loss. The specificity is 98%. This finding is less well established with volume depletion from other causes.[2]
signs of shock
End result of severe volume depletion resulting in poor tissue perfusion and ischaemia.
Other diagnostic factors
common
decreased urine output
Patient may note decreased urinary frequency or volume, or more concentrated urine.
diarrhoea
Patients with frequent and severe diarrhoea may be unable to maintain adequate oral intake to compensate for these losses, and so become volume-depleted. Older people and children are especially vulnerable.
vomiting
Patients with frequent and severe vomiting are often unable to maintain adequate oral intake to compensate for these losses and so become volume-depleted. Older people and children are especially vulnerable.
melaena
The passage of characteristic black, tarry, foul-smelling stool is indicative of blood from a gastric or duodenal haemorrhage that has passed through the ileum and colon. Such bleeds are a frequent cause of volume depletion.
haematochezia
The passage of significant amounts of bright red, bloody stool is an important indicator for the possibility of volume depletion.
high-volume gastrointestinal drainage
Hospitalised patients may become volume-depleted due to large volume losses from nasogastric suction or enteral drainage if they do not receive appropriate maintenance or replacement fluids.
polyuria
May be associated with uncontrolled diabetes and the presence of glucose in the urine, causing osmotic diuresis.
poor oral intake
A sustained poor intake of fluids and solutes can result in volume depletion. Children and older people are especially vulnerable.
severe sweating
Prolonged heavy physical exertion in warm environments, with limited access to solute and water replacement, can quickly lead to volume depletion.
burns
Likelihood depends on the size of the burn. If extensive, burns can quickly lead to volume depletion, as the fluid lost has a similar solute composition to plasma.
intestinal obstruction
As much as 7-8 L of fluid can be sequestered in the bowel, especially when the obstruction is distal.
severe pancreatitis
Substantial volumes may be sequestered in the retroperitoneum.
crush injuries
intra-abdominal bleeding
Substantial volumes may be lost into the abdominal cavity.
fatigue
Non-specific; may be a manifestation of decreased tissue perfusion.
thirst
Non-specific; may be seen with volume depletion alone, but is greatest in settings of true water depletion (dehydration and hypernatraemia), with or without hypovolaemia. Volume depletion can stimulate thirst, but an increase in serum osmolality, as seen in dehydration, is the strongest stimulus of thirst.
dry mucous membranes
Usually reflects associated dehydration. It is not a very useful sign in cases of acute, haemorrhage-related volume depletion.
uncommon
muscle cramps
May be a reflection of decreased tissue perfusion or electrolyte abnormalities.
abdominal pain
In patients with significant atherosclerosis of the mesenteric vasculature, abdominal ischaemia due to severe volume loss can result in abdominal pain. However, it can also be a symptom of intra-abdominal bleeding, bowel obstruction, or pancreatitis.
chest pain
Volume depletion in patients with coronary atherosclerosis can result in cardiac ischaemia and angina due to hypotension.
confusion
Non-specific; but may reflect poor cerebral blood flow or uraemia in the setting of impaired kidney function.
Risk factors
strong
diuretic therapy
Volume depletion often manifests after an increase in diuretic therapy or during an acute illness in a patient on diuretics.[16] In patients with heart failure, in particular, there is a delicate balance between euvolaemia and hyper- and hypovolaemia, and even small changes in diuretic dose or fluid intake can upset this balance.[17]
chronic kidney disease
With chronic renal vasoconstriction, a small drop in effective circulating volume can have large clinical effects.
older adult
These patients may have motivational or practical difficulties in preparing food and drink for themselves. They can easily become volume-depleted if appropriate amounts of water and solutes are not made readily available, or without assistance given to enable them to take in sufficient volumes.
altered mental status
Patients with a reduced level of consciousness who are unable to drink and regulate their own intake of water and solutes can become volume-depleted unless appropriate fluids are administered by nasogastric or intravenous routes.
weak
high ambient temperature
Prolonged heavy physical exertion in warm environments, with limited access to solute and water replacement, can quickly lead to volume depletion through excessive sweating.
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