Lecture 10 9/18/24

Question 1

What is the goal of the cardiovascular system?

Answer 1

provision of circulating blood to allow delivery of nutrients, removal of waste, and homeostasis maintenance

Question 2

What is CaO2?

Answer 2

amount of oxygen in arterial blood, mL/dL

Question 3

What is CO/cardiac output?

Answer 3

the amount of blood pumped in a given time, L/min

Question 4

What is the equation for delivery of oxygen?

Answer 4

DO2 = CO x CaO2

Question 5

Which contributing factors of DO2 are routinely monitored during anesthesia?

Answer 5

-MAP
-heart rate
-heart rhythm
-CaO2

Question 6

What are the characteristics of heart rate?

Answer 6

-quantitative
-important determinant of cardiac output
-sensitive indicator for change in physiologic status

Question 7

What are the characteristics of heart rhythm?

Answer 7

-normal sinus rhythm allows for normal CO
-arrhythmia may alter CO and thus tissue blood supply

Question 8

What is the primary method for monitoring heart rate and rhythm?

Answer 8

electrocardiogram

Question 9

What information can be presented on an ECG?

Answer 9

-rate
-regular vs irregular rhythm
-P wave for each QRS
-PR interval
-QRS for every P wave
-ST segment
-T wave

Question 10

What is palpated when assessing a pulse?

Answer 10

difference between SAP and DAP

Question 11

How do pulse deficits appear on ECG and arterial pressure graphs?

Answer 11

the arterial pressure graph does not have a wave for every QRS on the ECG, indicating inadequate filling to produce a pulse

Question 12

Why is pulse quality not a good surrogate for blood pressure?

Answer 12

pulse quality only relies on the difference between SAP and DAP, which can still be “good” even when the actual values are not

Question 13

What is a plethysmograph?

Answer 13

graph that provides an indication of pulsatile flow

Question 14

What are the methods for assessing pulsatile flow?

Answer 14

-plethysmograph
-pulse oximetry
-doppler

Question 15

What are the characteristics of the mucus membranes as a monitoring tool?

Answer 15

-qualitative
-oral mucosa is more reliable than tongue
-pink color indicates good oxygenation +/- perfusion
-pale/gray/white coloration indicates vasoconstriction, hypotension, and/or anemia
-gray/blue indicates cyanosis and hypoxemia
-bright red indicates vasodilation and/or shock

Question 16

What are the characteristics of capillary refill time?

Answer 16

-semi-quantitative
-normal value is around 1-2 seconds
-prolonged CRT results from vasoconstriction and decreased peripheral perfusion
-short CRT results from vasodilation

Question 17

What is arterial blood pressure?

Answer 17

quantitative assessment of hydrostatic pressure in the arteries

Question 18

Which blood pressure value is the best indicator of perfusion pressure?

Answer 18

MAP

Question 19

How is MAP calculated?

Answer 19

MAP = 1/3 (SAP- DAP) + DAP
MAP = CO x SVR

Question 20

What is hypotension?

Answer 20

-abnormally low blood pressure
-MAP < 60 mmHg
-SAP < 90 mmHg

Question 21

What are the characteristics of direct ABP monitoring?

Answer 21

-quantitative
-invasive blood pressure measurement
-gold standard
-arterial catheter + BP transducer equipment
-continuous, beat to beat updates

Question 22

What are the advantages of direct ABP monitoring?

Answer 22

-accurate
-continuous
-provides information regarding CO, wall tone, and arrhythmias

Question 23

What are the disadvantages of direct ABP monitoring?

Answer 23

-invasive
-technically difficult
-requires capable monitors
-complications such as thrombosis, infection, and ischemia

Question 24

How is blood pressure cuff size determined?

Answer 24

cuff width should equal roughly 40% of limb circumference

Question 25

How does an incorrectly sized blood pressure cuff impact BP reading?

Answer 25

-if the cuff is too loose or too large the reading is overestimated -if the cuff is too tight or too small the reading is underestimated

Question 26

What are the characteristics of doppler ABP monitoring?

Answer 26

-quantitative -non-invasive -requires appropriately sized cuff, sphygmomanometer, and doppler -doppler detects blood flow and transmits as an audible sound -when cuff pressure is greater than SAP, no sound produced -when SAP is just above cuff pressure, 1st doppler sound is heard; indicates SAP

Question 27

What are the advantages of doppler ABP monitoring?

Answer 27

-non-invasive -can be done on awake patients -easy -cheap

Question 28

What are the disadvantages of doppler ABP monitoring?

Answer 28

-only measures SAP -user error possible -accuracy issues with extremes of ABP, brady/tachycardia, arrhythmias, and small patients

Question 29

What are the characteristics of oscillometric ABP monitoring?

Answer 29

-quantitative -non-invasive -requires appropriately sized cuff and oscillometer -detects oscillations in cuff due to arterial pulsation -evaluates pressure at which oscillations change

Question 30

What are the advantages of oscillometric ABP monitoring?

Answer 30

-non-invasive -can be done on awake patients -easy -less expensive than IBP -gives SAP, DAP, and MAP values

Question 31

What are the disadvantages of oscillometric ABP monitoring?

Answer 31

-technical errors -accuracy issues with extremes of ABP, brady/tachycardia, and arrhythmias

Question 32

What is perfusion?

Answer 32

delivery of blood to the tissue

Question 33

How is perfusion measured?

Answer 33

-by measuring the output of waste products from the cells (lactate) -by measuring the oxygen difference between arterial and venous blood