Blood Pressure Monitoring Flashcards by Alex Sextro

in most organs does the blood flow/perfusion increase or decrease with increased BP?

increase

and decreases blood flow as BP decreases

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what organs autoregulate their blood flow?

brain
kidney
heart

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autoregulation of blood flow definition

the amount of blood flow/perfusion to these organs remains CONSTANT despite changes in BP (within autoreguation range)

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proposed cerebral autoregulation ranges

60-160mmHg

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If the BP in the brain goes above 160mmHg what happens to blood flow to the brain?

increases

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If the BP in the brain goes below range (50-60) what happens to blood flow to the brain?

decreases

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What happens to the autoregulation curve in a chronically hypertensive patient?

the curve is shifted to the right

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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

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What is the renal autoregulation range?

80-180mmHg

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What is the coronary autoregulation range?

50-120mmHg

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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

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What does preventing over perfusion to the brain do?

prevents increase in intracranial pressure

reduces the risk of brain injury

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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

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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

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When can autoregulation ability be impaired (4)?

ischemia
hypercarbia
acidosis
high end tidal concentration of volatile agent

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During anesthesia what should the anesthetist try to keep the patients BP within?

20-30% of their baseline BP value

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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)

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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

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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

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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)

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Patients undergoing intestinal surgery will usually have to do what?

bowel prep

requires 1000-1200mL to replace this fluid

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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)

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What are the 5 types of BP measurement?

auscultation
doppler (systolic only)
NIBP (oscillometry; cuff)
Noninvasive arterial line (tonometry)
arterial line

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other name for auscultation

sphygmomanometry

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laminar defintion

(of a flow) taking place along constant streamlines; not turbulent.

korotkoff sound

the sounds you hear when taking a BP with auscultation

When do you hear and not hear the korotkoff sounds?

korotkoff sounds disappear when artery is completely compressed (no blood flow) korotkoff sounds appear when partially compressed (blood flow turbulent) korotkoff sounds disappear when artery is completely open (blood flow is laminar)

what are the systolic and diastolic BPs in terms of korotkoff sounds?

systolic (appearance of korotkoff sounds) | diastolic (disappearance of korotkoff sounds)

when the BP cuff is inflated to a pressure above systolic what is the pulse amplitude?

low bc artery is compressed and no blood flow

when the BP cuff starts to deflate and the pressure in the cuff matches the systolic pressure what is the pulse amplitude?

starts to increase and the pulse is felt b/c the artery is less compressed

when the BP cuff deflates to the point of MAP what is the pulse amplitude

the pulse amplitude is at its maximum

when the BP cuff is deflated to diastolic pressure and below what is the pulse amplitude?

the pulse amplitude is small again and cannot be felt

Does the NIBP calculate the MAP from the systolic and diastolic?

no it measures the MAP separately

Is oscillometry equally as accurate with regular and irregular rhythms?

no irregular rhythms cause it to be more inaccurate

In order to get an accurate reading how much greater should the width of the cuff be than the diameter of extremity

20-50%

If the cuff is too large will the BP be an overestimation or underestimation?

underestimation | it must squeeze harder in order to flatten artery

if the cuff is too small will the BP be an overestimation or underestimation?

overestimation

what is the difference between the systolic pressure in the arm vs. leg in supine patient

10-20mmHg greater in the legs

what is the difference between diastolic pressure in the arm vs. leg in supine patient

- some sources say equal | - some sources say equal to or lower than arm

MAP in arm vs leg in supine patient

leg MAP is higher | increase in systolic was greater than decrease in diastolic

is the NIBP accurate when you cannot feel a distal pulse or the extremities are cold?

do different sites on the body give you different BPs? why is this important?

yes | important b/c blood flow to an extremity can be compromised and we need an accurate BP

What would happen if the surgeon was leaning on the BP cuff?

overestimated BP **important to make sure reading is accurate before treating**

Where should you not place the BP cuff (3)?

1- operative arm 2- same side as mastectomy or lymph node removal (lymphedema) 3- arm with AV fistula

AV fistula

artificial connection between artery and vein (vein gets big) allows for dialysis in renal failure patients

Non-invasive A line (tonometry)

gives a beat to beat BP by placing probe over wrist | senses the pressure required to flatten artery

disadvantages of non-invasive a lines (4)

sensitive to movement sensitive to placement needs frequent calibration no arterial access for labs

dialysis

excess waste and fluid is removed from the blood in patients with renal failure

what are the two types of dialysis

``` hemodialysis (HD) peritoneal dialysis (PD) ```

process of HD (3)

1- large vein and artery are accessed (via AV fistula, graft or central line) 2- machine draws blood from artery 3- machine purifies and returns via vein

What type of anesthesia does a person getting a AV fistula?

MAC anesthesia

AV graft

artificial tube that connects the artery to the vein

when is an AV graft indicated?

the patients blood vessels are too small to create a fistula

AV graft advantage

mature faster than fistulas

AV graft disadvantage

more likely to clot | infxn more likely

central line for dialysis

short term solution until fistula or graft created | double lumen

peritoneal dialysis

dialysis solution is infused into the peritoneal cavity, waste diffuses and then solution is drained

anesthetic management for renal failure (3)

1-pt usually anemic (decreased EPO) 2- restrict fluids as much as possible (500mL on microdrip) 3- cautious of any increase in serum potassium (LR or Sux)

if the patient is not supine what effects the BP?

gravity

NIBP cuff is placed higher on a reverse trendelenburg will the BP be higher or lower?

lower

In lateral decubitus position the BP reading on the dependent arm will be over or under estimated?

over estimated

how can BP in the head be estimated in non supine positions?

1- measure distance from cuff to head | 2- calculate the difference in BP at level of head

For each 1cm in height difference the MAP will be how much lower at the head??

0.77mmHg