Saturday, October 31, 2009

Definition of Hemodynamically Unstable?

In the pediatric population.
hemodynamically unstable means..that having problem in circulation..hemo means blood and dynamic means there's trouble in the motion of hyperdynamic circulation this is caused by many things...inwhich there's rapid shift of blood from the arterial side to the venous side...hyperthyrodism(incre... secretion of thyroid gland) causes hyoer dynamic circulation and anaemia causes hyperdynamic circulation...these r called problems in the peripheral circulation.that can lead to abnormalities in heart work..there's also the opposite of hyperdynamic circulation which is the slugguish circulation ..slow shift of blood from arterial to venous side.caused by polycycemia which is the abnormal increase in the count of red blood cells.
I used to take care of sick kids (now only adults). There are several reasons why we use the term "hemodynamically unstable" -- all relate to the patient's inability to autoregulate blood pressure in response to environmental stressors such as being lifted or turned in a bed or stretcher, to being able to maintaining their basal metabolism.
If a patient's blood pressure remains within the normal range to allow sufficient end organ perfusion (for several hours), even with postural movements (e.g. sitting up), without the need for intervention, they are hemodynamically stable.
If IV meds (inotropes) or transfusions of fluids (e.g. blood) are requires to sustain the blood pressure within acceptable parameters, they are said to be hemodynamically compromised a.k.a. "hemodynamically unstable".
The following are a few examples I can think of in which the term "hemodynamically unstable" would be applied:
1) The patient requires an intravenous inotrope drip (e.g. dopamine, norepinephrine, epinephrine, or some combination) to maintain an adequate mean arterial pressure (MAP) or systolic pressure (SBP) -- both required for vital end-organ perfusion (SBP is only an issue when a part of the brain has too much pressure on it, is swelling, or the arteries supplying parts of the brain are in vasospasm, such that the autoregulatory mechanisms that shunt blood to areas with higher glucose demand are failing).
2) The patient has ongoing internal bleeding that is being treated with blood transfusions and other blood products (to maintain a stable blood volume or preload).
3) The patient's heart pauses or eratically dips into a low rate (despite the body's requirement for a higher one) such that the patient needs a programmed, temporary pacemaker (e.g. a transcutaneous or transvenous pacemaker).
Basically, the same principles apply to adult patients as they do to kids, but kids are more difficult to manage (in general) if they are hemodynamically compromised. Generally, the term applies when it is essential that constant cardiovascular monitoring *and* intervention is required to enable the patient's brain, heart, lungs and other major organs to receive the right amount of blood to function normally.

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