Patient/caregiver was educated on pathophysiology of orthostatic hypotension as follows:
- Orthostatic hypotension is a sudden drop in blood pressure, secondary to abrupt change in body posture.
- A sudden drop of atleast 20 mm Hg in systolic blood pressure or a drop of atleast 10 mm Hg in diastolic blood pressure, induced by change in body position, would qualify for orthostatic hypotension.
- The symptoms are usually experienced, when an individual assumes a sudden erect posture, from either prolonged lying down or sitting.
- Venous blood in the lower extremities must travel in the upward direction, overcoming gravity, towards the heart. To facilitate movement of blood in upward direction, the big veins of the lower limbs have valves that continuously push the blood up, against gravity, towards the heart.
- Also, when the heart pumps oxygenated blood to the head & neck and brain, this blood must travel in the arteries in the upward direction, overcoming gravity. Optimal blood pressure in the arteries can act as a driving force to move the blood in the upward direction, to provide blood, oxygen, and nutrient suppl, and nutrient supply to the brain.
- Any factors that can compromise this upward movement of blood to the head and brain can result in orthostatic hypotension. Gravity is a force always acting in downward direction, inhibiting this movement of blood in the upward direction, to reach head and brain.
- When an individual is in a lying down position or sitting, the effect of gravity is not significant. When an individual changes the position suddenly, for example, assuming a standing position from prolonged sitting or a lying down position, gravity comes into play.
- Gravity, as a force always acting in downward direction, tends to retain more blood volume in the veins and lower portions of the body and inhibits the movement of blood in upward direction, to head and brain.
- Pooling of more blood volume in the veins and lower portions of the body result in suddenly reduced blood volume in circulation and abrupt drop in the blood pressure numbers.
- In all healthy individuals, to prevent blood pressure dropping too low, body triggers a compensatory increase in heart rate and narrowing of blood vessels. Increased heart rate with narrowing of blood vessels try to maintain the blood pressure numbers and prevent them dropping too low.
- This compensatory response could fail, especially in senior citizens, resulting in severe and abrupt drop in blood pressure, resulting in orthostatic hypotension.
- Reduced blood supply to head and brain can result in symptoms of orthostatic hypotension, such as, episodes of dizziness and confusion.
