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WHAT IS HYPOVOLEMIA?
Hypovolemia basically means low blood volume. "Hypo" means
low, "vol" is for volume, and "emia" refers to blood.
The reduction of blood volume in hypovolemia means there is a reduction
of oxygen carrying capcity. Thus, symptoms of hypovolemia may include
cold hands and feet, light headedness, infrequent urination, increased
heart rate, and weakness.
Low blood volume due to hemorrhage is most commonly be caused by accidental
trauma or internal ailments such as gastro-intestinal bleeding. Dehydration
can also contribute to hypovolemia, though it's usually not a cause
under normal circumstances. .
Losing about 1/5 or more of the normal amount of blood in your body
causes hypovolemic/hemorrhagic shock to various degrees. Loss of red
blood cells decreases oxygen carrying capacity - the body compensates
by increasing cardiac output (your heart rate and blood pressure) to
maintain oxygen levels, and also steps up oxygen extraction. For mild
to moderate blood loss, fluid solutions (saline or Lactated Ringer's
Solution [a/k/a "LRS"] ) may be used to restore fluid volume.
In more severe stages of hypovolemia, however, blood transfusions are
required because the blood loss (and resultant lack of oxygen carrying
capacity) is too much for the body to compensate for, even with IV fluids.
The patient may exhibit high anxiety, especially if they're prone to
anxiety in the first place, as well as shivering from feeling constantly
cold.
STAGES OF HYPOVOLEMIA
- Stage I Hemorrhage
Involves up to 15% (apx. 750ml) of blood volume. There is typically
no change in vital signs and fluid resuscitation is not usually necessary.
* Compensated by constriction of vascular bed
* Blood pressure maintained
* Normal respiratory rate
* Pallor of the skin
* Slight anxiety
- Stage II Hemorrhage
Involves 15-30% (apx. 750–1500 ml) of total blood volume. A patient
is often tachycardic (rapid heart beat) with a narrowing of the difference
between the systolic and diastolic blood pressures. The body attempts
to compensate with peripheral vasoconstriction (narrowing of blood vessels).
Skin may start to look pale and be cool to the touch. The patient may
exhibit slight changes in behavior. Intravenous fluid resuscitation
with crystalloids (Saline solution or Lactated Ringer's solution) is
all that is typically required. Blood transfusion is not typically required.
* Cardiac output cannot be maintained by arterial constriction
* Tachycardia >100bpm (rapid heart rate)
* Increased respiratory rate
* Blood pressure maintained
* Increased diastolic pressure
* Narrow pulse pressure
* Sweating from sympathetic stimulation
* Mildly anxious/Restless
- Stage III Hemorrhage
Involves loss of 30-40% (apx. 1500–2000 ml) of circulating blood
volume. The patient's blood pressure drops, the heart rate increases,
peripheral perfusion (shock), such as capillary refill worsens, and
the mental status worsens. Fluid resuscitation with crystalloid (Saline
solution or Lactated Ringer's solution) and blood transfusion are usually
necessary.
* Systolic blood pressure falls to 100mmHg or less
* Classic signs of hypovolemic shock
* Marked tachycardia >120 bpm (heart rate - beats per minute)
* Marked tachypnea >30 bpm (rapid breathing - breaths per minute)
* Decreased systolic pressure
* Alteration in mental status (Anxiety, Agitation)
* Sweating with cool, pale skin
- Stage IV Hemorrhage
Involves loss of over 40% (>2000mls) of circulating blood volume.
The limit of the body's compensation is reached and aggressive resuscitation
is required to prevent death.
* Extreme tachycardia with weak pulse
* Pronounced tachypnea
* Significantly decreased systolic blood pressure of 70 mmHg or less
* Decreased level of consciousness
* Skin is sweaty, cool, and extremely pale (moribund)
TREATMENT OPTIONS
Stage II or worse should always always ALWAYS be evaluated and treated
by medical professionals.
Stage I may be treated at home, but monitor carefully if the cause
is unknown (internal bleeding does not always leave visible signs or
bruising) so that if it gets worse , proper treatment can be obtained
as soon as possible.
OTHER INFORMATION
Blood pressure (BP) is the pressure exerted by circulating blood on
the walls of blood vessels, and is one of the principal vital signs.
During each heartbeat, BP varies between a maximum (systolic) and a
minimum (diastolic) pressure. The mean BP decreases as the circulating
blood moves away from the heart through arteries, has its greatest decrease
in the small arteries and arterioles, and continues to decrease as the
blood moves through the capillaries and back to the heart through veins.
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