Hypotension (Low blood pressure)
During hemodynamic stress such as exercise and standing adequate blood pressure is maintained by barorecptor, volume receptor chemoreceptor and pain receptor. However, in the presence of certain cardiovascular abnormalities, these mechanisms may fail to regulate blood pressure correctly; when these occurs, a person may experience transient or sustained hypotension.
As a practical definition, hypotension exists when symptoms are caused by low blood pressure.
Symptoms:
- Lightheadedness
- Fainting
- Blurred vision
- Nausea
- Cold, pale skin
- Rapid shallow breathing
- Fatigue
- Depression
- Thirst
- Coma
Causes: Hypotension may be due to neurogenic or nonneurogenic factors.
Neurogenic causes include autonomic dysfunction or failure, which can occur in association with other central nervous system abnormalities, such as Parkinson’s disease , or may be secondary to systemic diseases that can damage the autonomic nerves, such as diabetes or amyloidosis; vasovagal hyperactivity; hypersensitivity of the carotid sinus; and drugs with sympathetic stimulation or blocking properties .
Nonneurogenic causes of hypotension include vasodilatation caused by alcohol, drugs or fever; cardiac disease (e.g., cardiomypathy, valvular disease); or reduced blood volume secondary to hemorrhage, dehydration, or other causes of fluid loss. In may patients, multiple causative factors are involved.
Diagnosis:
Hypotension is diagnosis by history, physical examination but some other investigation (EKG, echo) to rule out underlying diseases.
Treatment:
The symptomatic hypotension is to eliminate the underlying cause whenever possible, which, in some causes, produces satisfactory results. When this approach is not possible, other adjunctive measures may be necessary, especially when the symptoms are disabling. Common treatment modalities include avoidance of factors that can precipitate hypotension (e.g., sudden changes in posture, hot environment, alcohol, certain drugs, large meals), volume expansion (usually salt supplements and/or medication with salt-retaining/volume-expanding properties), and mechanical measures (including tight-fitting elastic compression stockings or pantyhose to prevent the blood from pooling in the veins of the legs upon standing).
Unfortunately, even when these measures are employed, some patients continue to have severe, debilitation effects from hypotension.
References:
- Medical physiology, Lippincott Williams & Wilkins 3rd edi.
- mayoclinic.com
- medicinenet.com
- nhlbi.nih.gov
- health.nytimes.com
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