Test 2: 27 cardiovascular

Question 1

what range of blood pressure can organs autoregulate? and which organs do this?

Answer 1

brain, heart, kidney
601-160 MAP

Question 2

how to measure HR

Answer 2

Stethoscope (external or esophageal)
* Direct measure of heart rate
* Arrhythmias and murmurs audible

Doppler monitor
* Direct measure pulse rate

Pulse Oximetry
* Pulse rate measured

Direct arterial pressure
* Pulse rate measured

ECG
* Electrical rate- may not correlate with generated pulses

Question 3

DAP— mmHg needed for adequate cardiac perfusion

Answer 3

> 40

Question 4

how to calculate MAP

Answer 4

Mean=diastolic + 1/3 (systolic-diastolic)

Question 5

Pressure (mean)=Flow (CO) x —

Answer 5

resistance (SVR)

can have good pressure from constricting vessels but the resistance can be too high for actual flow, need a balance

Question 6

Hypotension (MAP < —mmHg, SAP < — mmHg)

Answer 6

60
80

Ideally want to keep MAP> 80, SAP >100

Question 7

two non invasive BP devices

Answer 7

• Doppler Ultrasound
• Oscillometric

Question 8

two invasive ways to measure BP

Answer 8

• Pressure Transducer
• Simple Aneroid Gauge Method

Question 9

how does doppler work

Answer 9

ultrasonic crystal probe has two crystals: one for transmitting ultrasonic waves and one for detecting reflected waves

Arterial blood flow is detected and reflected wave frequencies are converted to an audible signal

Question 10

doppler readings in cats and dog where you should intervene

Answer 10

• Dogs doppler < 100mm Hg
• Cats doppler < 80 mm Hg

Question 11

how does oscillometric determine BP

Answer 11

measures Mean and then calculates systolic and diastolic via an algorithm

S/D may be different then if you have a direct measurment

Question 12

some factors that affect accuracy of non invasive BP

Answer 12

Cuff Size
Site-as cuff moves distally systolic increases and diastolic decreases
Arm position-cuff should be at level of heart
ARRHYTHMIAS?
Artifacts from motion are possible: shivering, trembling

Question 13

Non invasive BP decreases in accuracy with

Answer 13

extremes of pressure: very hypo or hypertensive
very high or very low HR

Question 14

what are some disadvantages of non invasive BP

Answer 14

not continous measurements- difficult to detect rapid changes

Clinical limitations:
* Decreased accuracy with extremes of BP and HR
* Not appropriate for critical patients
* Not appropriate when significant surgical complications are anticipated
(hemorrhage)
* Depending on brand may be less reliable in patients less than 10 kg (cats)?

Question 15

benifits of invasive BP

Answer 15

• accurate
• directly measures systolic and diastolic- mean is calculated
• Wave form is produced which can provide additional information about CV function: pulse contour often correlates with CO
• continous real time readings

Question 16

how does invasive BP work

Answer 16

• A column of fluid is directly connected between the arterial system and a pressure transducer
• Pressure waveform of arterial pulse is transmitted via the fluid to the transducer
• waveform is converted to electrical signal
• Signal is processed, amplified and converted into a visual display on a monitor

Question 17

Answer 17

arterial pressure wave from invasive BP

Question 18

what is damping of invasive BP

Answer 18

underdamping- gives you too high readings

overdamping- falsely low readings

Question 19

Answer 19

simple aneroid gauge

inexpensive way to measure invasive BP

only gives MAP- no SAP or DAP

Question 20

how does central venous pressure work

Answer 20

• way to measure preload
• assess response to fluid therapy
• pressure is measured in the cranial vena cava just proximal to the right atrium- estimates R atrial pressure
• makes a waveform that can provide additional info about cardiac function

Question 21

what is the bottom line

Answer 21

CVP (central venous pressure) waveform

Question 22

— can cause increased CVP valves

Answer 22

cardiac disease can cause falsely high CVP values

to measure CVP you need to consider cardiac output

Question 23

what is pulse pressure variation

Answer 23

change between diastolic and systolic from beat to beat

measure of fluid responsiveness

Pulse Pressure Variation > 15 % can indicate decreased preload (volume responsive)

Question 24

how to measure stroke volume

Answer 24

hard to do- need special imaging

echo, CT, MRI

Question 25

what are some physical signs that show afterload

Answer 25

afterload = systemic vascular resistance

increased afterload will decrease SV

pale= constricted, red= dilated
CRT < 1 s vasodilated, >2s vasoconstricted
Temp: cold constricted, warm dilated

Question 26

what are some ways to measure cardiac output

Answer 26

Fick- indirect NICO
thermodilution
Lithium dilution
arterial waveform analysis
echo
capnography