Things worth knowing about "Hypovolaemia"
Hypovolaemia refers to an abnormally reduced volume of blood or fluid circulating in the body. It can become life-threatening and requires prompt medical treatment.
What is Hypovolaemia?
Hypovolaemia is a medical condition in which the volume of blood or fluid circulating in the body is critically reduced. As a result, the heart is unable to pump sufficient blood to the organs, leading to inadequate supply of oxygen and nutrients. In severe cases, this progresses to hypovolaemic shock, a life-threatening medical emergency.
Causes
Hypovolaemia can result from various mechanisms that lead to the loss of blood or body fluids:
- Bleeding: external or internal injuries, surgery, gastrointestinal haemorrhage
- Severe vomiting or diarrhoea: causing rapid loss of fluid and electrolytes
- Excessive sweating: for example during fever, intense physical exertion, or heat exposure
- Burns: large-area burns cause massive fluid loss through the skin
- Excessive urination: e.g. in uncontrolled diabetes mellitus or diabetes insipidus
- Insufficient fluid intake: dehydration due to inadequate drinking
Symptoms
The symptoms of hypovolaemia depend on the severity of fluid loss and can worsen rapidly:
- Dizziness and light-headedness, especially when standing up (orthostatic hypotension)
- Rapid heartbeat (tachycardia)
- Drop in blood pressure (hypotension)
- Dry mucous membranes and reduced skin turgor
- Decreased urine output, potentially leading to anuria
- Pallor, cold sweating, and rapid breathing
- Confusion or loss of consciousness in severe cases
Diagnosis
Diagnosis of hypovolaemia is based on a combination of clinical assessment and laboratory tests:
- Clinical evaluation: blood pressure, heart rate, skin condition, capillary refill time
- Blood tests: haematocrit, haemoglobin, serum creatinine, electrolytes, lactate
- Urinalysis: urine osmolality and sodium to assess renal function
- Imaging: ultrasound to detect internal bleeding or fluid collections
- Central venous pressure (CVP): measured in intensive care to assess circulatory filling status
Treatment
The goal of treatment is to rapidly restore the circulating blood and fluid volume:
Fluid Replacement
In mild hypovolaemia, oral fluid intake may be sufficient. In severe cases, intravenous (IV) fluid administration is required:
- Crystalloid solutions (e.g. 0.9% NaCl, Ringer's lactate): first choice in most cases
- Colloid solutions (e.g. albumin): used in specific clinical situations
- Blood transfusions: indicated in cases of significant blood loss and severe oxygen deficiency
Treatment of the Underlying Cause
Alongside fluid replacement, the underlying cause must be addressed, for example haemostasis in bleeding, antiemetics for vomiting, or insulin administration in diabetes.
Intensive Care Measures
In hypovolaemic shock, intensive care interventions are required, including monitoring of vital signs, oxygen therapy, and if necessary the use of vasopressors to stabilise circulation.
References
- Vincent, J.L. & De Backer, D. (2013): Circulatory shock. In: New England Journal of Medicine, 369(18), 1726-1734.
- World Health Organization (WHO): Emergency Triage Assessment and Treatment (ETAT) Guidelines.
- Marino, P.L. (2014): The ICU Book. 4th edition. Lippincott Williams & Wilkins, Philadelphia.