Blood Pressure Monitoring COPY Flashcards
in most organs does the blood flow/perfusion increase or decrease with increased BP?
increase
and decreases blood flow as BP decreases
what organs autoregulate their blood flow?
brain
kidney
heart
autoregulation of blood flow definition
the amount of blood flow/perfusion to these organs remains CONSTANT despite changes in BP (within autoreguation range)
proposed cerebral autoregulation ranges
60-160mmHg
If the BP in the brain goes above 160mmHg what happens to blood flow to the brain?
increases
If the BP in the brain goes below range (50-60) what happens to blood flow to the brain?
decreases
What happens to the autoregulation curve in a chronically hypertensive patient?
the curve is shifted to the right
What does an autoregulation curve shifted to the right mean for BP maintenance?
It means that the blood flow to the brain will decrease at a higher MAP than a healthy patient
What is the renal autoregulation range?
80-180mmHg
What is the coronary autoregulation range?
50-120mmHg
What do the local blood vessels that supply autoregulation organs do during hypotension or hypertension?
adjust their tone
example: cerebral hypotensive: vasodilate and increase perfusion
cerebral hypertensive: vasoconstrict and prevents over perfusion
What does preventing over perfusion to the brain do?
prevents increase in intracranial pressure
reduces the risk of brain injury
What happens if the MAP falls below autoregulatory range?
still receive blood flow but not as much
amount of blood flow of autoreg organs will be proportional to the BP
What happens if the MAP rises above the autoregulatory range?
will receive more blood flow than they should
amount of blood flow of autoreg organs will be proportional to the patients BP
When can autoregulation ability be impaired (4)?
ischemia
hypercarbia
acidosis
high end tidal concentration of volatile agent
During anesthesia what should the anesthetist try to keep the patients BP within?
20-30% of their baseline BP value
If a patient has a starting BP of 185/105 with MAP= 132; what should you not let the MAP fall below?
92mmHg MAP (30% below)
What is controlled hypotension?
when surgeons ask for hypotension on purpose to decrease bleeding at the surgical site and improve the view through a scope
what cautions should an anesthetist take during controlled hypotension (3)?
- dont allow as much hypotension in ill or chronic hypertensive pts
- don’t allow the same amount of hypotension if the patient is in beach chair postion
- communicate concerns with surgeon
what are the etiologies (causes) of hypotension (8)?
1- hypovolemia (NPO, blood loss) 2- vasodilation (anesthetics, sepsis) 3- patient positioning 4- vagal response 5- need for stress dose of steriods 6- decreased cardiac contractility/EF (lower CO) 7- BP cuff too large 8- lateral decubitus (depends on the arm you put it on)
Patients undergoing intestinal surgery will usually have to do what?
bowel prep
requires 1000-1200mL to replace this fluid
treatments for hypotension (5)?
1- vasoconstriction (phenylephrine or lower volatile agent)
2- increase intravascular volume (if hypovolemic: LR, N/S, albumin, blood)
3- change pt position
4- administer inotropes (if heart failure: epi)
5- stress dose of steroids (chronic steroid use)
What are the 5 types of BP measurement?
auscultation doppler (systolic only) NIBP (oscillometry; cuff) Noninvasive arterial line (tonometry) arterial line
other name for auscultation
sphygmomanometry
laminar defintion
(of a flow) taking place along constant streamlines; not turbulent.