Hypovolemia is a state of decreased blood volume; more specifically, decrease in volume of blood plasma. It is thus the intravascular component of volume contraction (or loss of blood volume due to things such as bleeding or dehydration), but, as it also is the most essential one, hypovolemia and volume contraction are sometimes used synonymously. Hypovolemia is characterized by sodium depletion (salt depletion) and thus differs from dehydration, which is defined as excessive loss of body water.
1 Causes 2 Diagnosis
2.1 Stages of hypovolemic shock
3.1 Field care 3.2 Hospital treatment
4 History 5 See also 6 References 7 External links
Causes Common causes of hypovolemia are:
Loss of blood (external or internal bleeding or blood donation) Loss of plasma (severe burns and lesions discharging fluid) Loss of body sodium and consequent intravascular water; e.g. diarrhea or vomiting
Excessive sweating is not a cause of hypovolemia, because the body
eliminates significantly more water than sodium.
Clinical symptoms may not be present until 10–20% of total
whole-blood volume is lost.
Hypovolemia can be recognized by tachycardia, diminished blood
pressure, and the absence of perfusion as assessed by skin signs
(skin turning pale) and/or capillary refill on forehead, lips and nail
beds. The patient may feel dizzy, faint, nauseated, or very thirsty.
These signs are also characteristic of most types of shock.
Note that in children compensation can result in an artificially high
blood pressure despite hypovolemia. Children will typically compensate
(maintain blood pressure despite loss of blood volume) for a longer
period than adults, but will deteriorate rapidly and severely once
they do begin to decompensate. This is another reason (aside from
initial lower blood volume) that even the possibility of internal
bleeding in children should almost always be treated aggressively.
Obvious signs of external bleeding should be noted while remembering
that people can bleed to death internally without any external blood
loss. ("Blood on the floor, plus 4 more" = intrathoracic,
intraperitoneal, retroperitoneal, pelvis/thigh)
There should be considered possible mechanisms of injury that may have
caused internal bleeding, such as ruptured or bruised internal organs.
If trained to do so and if the situation permits, there should be
conducted a secondary survey and checked the chest and abdomen for
pain, deformity, guarding, discoloration or swelling.
Stage 1 Stage 2 Stage 3 Stage 4
Blood loss Up to 15% (750 mL) 15–30% (750–1500 mL) 30–40% (1500–2000 mL) Over 40% (over 2000 mL)
Blood pressure Normal (Maintained by vasoconstriction) Increased diastolic BP Systolic BP < 100 Systolic BP < 70
Slight tachycardia (> 100 bpm)
Respiratory rate Normal Increased (> 20) Tachypneic (> 30) Extreme tachypnea
Mental status Normal Slight anxiety, restless Altered, confused Decreased LOC, lethargy, coma
Skin Pallor Pale, cool, clammy Increased diaphoresis Extreme diaphoresis; mottling possible
Capillary refill Normal Delayed Delayed Absent
Urine output Normal 20–30 mL/h 20 mL/h Negligible
Treatment Field care The single most important step in the treatment of hypovolemic shock is to identify and control the source of bleeding. Emergency oxygen should be immediately employed to increase the efficiency of the patient's remaining blood supply. This intervention can be life-saving. The use of intravenous fluids (IVs) may help compensate for lost fluid volume, but IV fluids cannot carry oxygen in the way that blood can; however, blood substitutes are being developed which can. Infusion of colloid or crystalloid IV fluids will also dilute clotting factors within the blood, increasing the risk of bleeding. It is current best practice to allow permissive hypotension in patients suffering from hypovolemic shock, both to ensure clotting factors are not overly diluted and also to stop blood pressure being artificially raised to a point where it "blows off" clots that have formed. Hospital treatment Fluid replacement is beneficial in hypovolemia of stage 2, and is necessary in stage 3 and 4. See also the discussion of shock and the importance of treating reversible shock while it can still be countered. For a patient presenting with hypovolemic shock in hospital the following investigations would be carried out:
Blood tests: U+Es/Chem7, full blood count, glucose, blood type and
Central venous catheter
The following interventions would be carried out:
IV access Oxygen as required Surgical repair at sites of hemorrhage Inotrope therapy (Dopamine, Noradrenaline) which increase the contractility of the heart muscle Fresh frozen plasma or whole blood
Vasopressors (like Norepinephrine, Dobutamine) should generally be avoided, as they may result in further tissue ischemia and don't correct the primary problem. Fluids are the preferred choice of therapy. History In cases in which loss of blood volume is clearly attributable to bleeding (as opposed to, e.g., dehydration), most medical practitioners of today prefer the term exsanguination for its greater specificity and descriptiveness, with the effect that the latter term is now more common in the relevant context. See also
Exsanguination Hypervolemia Non-pneumatic anti-shock garment Polycythemia, an increase of the hematocrit level, with the "relative polycythemia" being a decrease in the volume of plasma Volume status
Hypovolemia definition - MedicineNet - Health and Medical
Information Produced by Doctors". Medterms.com. 2012-03-19. Retrieved
Hypovolemia definition of hypovolemia by Medical dictionary".
Medical-dictionary.thefreedictionary.com. Retrieved 2015-11-01.
V · T · D
ICD-10: E86, R57.1, T81.1 ICD-9-CM: 276.52 MeSH: D020896
CRISP Thesaurus 00004050[dead link]
v t e
Electrolyte imbalance and acid–base imbalance (E86–E87, 276)
Volume contraction (dehydration/hypovolemia) Hypervolemia
Hypernatremia Salt poisoning
Metabolic: High anion gap
Ketoacidosis Diabetic ketoacidosis Alcoholic ketoacidosis Lactic
Normal anion gap
Hyperchloremic Renal tubular
Mixed disorder of acid-base balance
v t e
Symptoms and signs relating to the cardiovascular system (R00–R03, 785)
Referred pain Angina Aerophagia
Split S2 S3 S4 Gallop rhythm
Systolic Diastolic Continuous
Pericardial friction rub Heart click Bruit
Tachycardia Bradycardia Pulsus tardus et parvus Pulsus paradoxus doubled
Pulsus bisferiens Dicrotic pulse Pulsus bigeminus
Cœur en sabot Jugular venous pressure
Cannon A waves
Cardiogenic Hypovolemic Distributive