Volume Depletion

Question 1

Defintion?

Answer 1

Volume depletion is a reduction in extracellular fluid volume that occurs when salt and fluid losses exceed intake on a sustained basis.

Question 2

RF?

Answer 2

• Diuretics
• CKD
• Old age
Confusion

Question 3

Epidemiology?

Answer 3

Age: Older
Sex:
Ethnicity:
P:

Question 4

Aetiology?

Answer 4

Extra renal
Renal
Adrenal
Pituitary

Question 5

Extrarenal cause?

Answer 5

bleeding
dialysis
GI
Skin
3rd-space losses

Question 6

Renal

Answer 6

AKI

Question 7

Adrenal

Answer 7

insufficiency,hypoaldosteronism,Bartter syndrome,Gitelman syndrome

Question 8

Hypothalamic/PI

Answer 8

central DI
osmotic diuresis/DM
diuretics
salt-wasting renal disease

Question 9

CP?

Answer 9

• Postural dizziness
• Weight loss
• Orthostatic hypotension
• Postural tachycardia
• Signs of shock
• Low urine output
• N and V
• Burns
• Sweating
Thirst

Question 10

Pathophysiology-isotonic?

Answer 10

• Vomiting and diarrhea:severe watery diarrhea and/or vomiting can be a life-threatening condition, especially in children. People withgastroenteritismay lose tremendous amounts of fluids and electrolytes in a short time and their oral replacement is limited due to recurrent vomiting, which can result in severe dehydration.
  
  • Excessive sweating:vigorous exercise, especially in humid weather, will increase sweating and lead to fluid and electrolyte loss.
  • If dehydration is not corrected, it will lead torenal injuryfrommuscle breakdownandlactic acidosis.

Question 11

Pathophys-hypertonic?

Answer 11

• Fever:Fever will increase the respiratory rate and therefore, water loss. Sweating also increases in order to lower the body temperature. Water intake is commonly decreased during a fever which will aggravate dehydration
  
  • Polyuria:Increased water loss in the urine causes hypertonic dehydration and may occur indiabetes mellitus,diabetes insipidus,orwithdiuretic use.
  • Decreased water intake
  • Excessive sweating
  • End-stage renal disease
  • Drinking urine or seawater for survival

Question 12

Pathophys-hypotonic?

Answer 12

• Addison’s disease
  
  • Renal tubular acidosis
  • Iatrogenic causes:hypotonic fluids or regular saline used for IV hydration in patients with heat stroke or diarrhea
  • Diuretics:loop,thiazide, and osmotic diuretics especially with prolonged use
  • Cystic fibrosis

Question 13

Investigations first line?

Answer 13

• Exam and History
• FBC-blood loss
• Serum electrolytes, urea, creatinine-hypernatremia, hypo/hyperkalaemia
• Urinalysis-high specific gravity density-dehydration
• Urine sodium-<20 mmol/L
• Urine osmolality->450 mmol/kg
• FOBT-positive if blood loss

Question 14

Investigations-second line?

Answer 14

• Investigations for underlying cause of vol depletion

Question 15

Management first line?

Answer 15

• Replace fluids-
• IV isotonic crystalloid
• Packed RBCs, FFP and treated source of bleeding
• Anti-emetics/anti-diarrhoeals if GI loss
• IV isotonic sodium bicarbonate
• IV vasopressors
• Withhold diuretics
• Treat burns
• Isotonic saline if third-space sequestration (can’t be reabsorbed) or pulmonary losses
Oral rehydration

Question 16

Management second line?

Answer 16

• IV lactated Ringer’s solution-
• Ringer’s lactate and other buffered solutions have lower chloride concentrations and may reduce development of hyperchloremic metabolic acidosis.
• Anti-emetics/anti-diarrhoeals if GI loss
• IV isotonic sodium bicarbonate
IV vasopressors

Question 17

Prognosis?

Answer 17

Depends on severity, underlying cause, and speed of management

Question 18

Complications?

Answer 18

• Peripheral/pulmonary oedema
• Hypovolaemic shock
• Electrolyte disturbances
• Acid base disturbances
• Acute tubular necrosis
• AKI