Mod1: Monitoring for Cardiac Surgery - BLOOD PRESSURE MONITORING

Question 1

_{BLOOD PRESSURE MONITORING​}

What is the Most frequently monitored hemodynamic variable?

Answer 1

BLOOD PRESSURE

Question 2

_{BLOOD PRESSURE MONITORING​}

Which information is made available to us via the MAP?

Answer 2

Organ perfusion

_{(Especially Brain, Liver and Kidneys)}

Question 3

_{BLOOD PRESSURE MONITORING​}

Which information is made available to us via the diastolic blood pressure?

Answer 3

Coronary perfusion

_{(Coronaries feel during diastole)}

Question 4

_{BLOOD PRESSURE MONITORING}

Which information is made available to us via the Pulse pressure?

Answer 4

Stroke Volume

^{(Volume status)}

CO

SVR

Question 5

_{BLOOD PRESSURE MONITORING}

Why is Noninvasive BP not typically used as primary BP monitoring during CPB?

Answer 5

Inadequacy of monitoring hemodynamic parameters

Inaccurate at extreme pressures

Intermittent data, not continuous

Requires pulsatile flow (which is not available during CPB)

Often used merely as adjunct to direct arterial blood pressure monitoring

Question 6

_{BLOOD PRESSURE MONITORING}

What remains the “Gold Standard” for monitoring BP during cardiac surgery?

Answer 6

Direct arterial blood pressure

Question 7

_{BLOOD PRESSURE MONITORING}

What are advantages of Direct arterial blood pressure monitoring?

Answer 7

Displays real-time blood pressure monitoring

Allows for pharmacological or mechanical BP manipulation while maintaining awareness of beat to beat BP

Allows for analysis of waveform can give information on SVR, SV, and cardiac output

Allows for close monitoring of ABG’s, coagulation (ACT’s), and electrolytes

Allows for Direct ABP monitoring possible during non-pulsatile CPB

Question 8

_{BLOOD PRESSURE MONITORING}

Which information can be gathered via analysis of direct arterial BP waveform?

Answer 8

Cardiac Output

SV

SVR

Question 9

_{INTERPRETING ARTERIAL WAVEFORM}

Which wave on the QRS complex represents the begining of systole?

Answer 9

The R-wave

Question 10

_{INTERPRETING ARTERIAL WAVEFORM}

When does the arterial pulse wave occur in reference to the ECG tracing?

Answer 10

160-180 milliseconds after the R-wave

Question 11

_{INTERPRETING ARTERIAL WAVEFORM}

What happens during the Systolic phase or Systolic upstroke?

What is it associated with on the ECG tracing?

Answer 11

Begins with a Rapid increase of pressure to a peak

Opening of the Aortic valve

Blood ejecting into the aorta from LV

Peak systole = Systolic BP

Follows the R-wave on EKG

Question 12

_{INTERPRETING ARTERIAL WAVEFORM}

What happens during the Systolic runoff?

Answer 12

Represents the time when

the eflux of blood out of the ventricle is lower than

the influx of blood into the aorta

Question 13

_{INTERPRETING ARTERIAL WAVEFORM}

What does the Dicrotic notch represents?

Answer 13

Closure of the aortic valve

Question 14

_{INTERPRETING ARTERIAL WAVEFORM}

What happens during the “diastolic runoff”?

Answer 14

Drop in pressure that occurs after the aortic valve closes

Blood is now going into the peripheral circulation

Question 15

_{INTERPRETING ARTERIAL WAVEFORM}

What does End-Diastolic-Blood-Pressure (EDBP) also referred to as “Aortic Diastolic Pressure” represents?

Answer 15

Pressure exerted by the vasculature back onto the aortic valve

Question 16

_{INTERPRETING ARTERIAL WAVEFORM}

What reflects DBP on the arterial waveform?

Answer 16

Lowest reading before the next systolic upstroke

Question 17

_{INTERPRETING ARTERIAL WAVEFORM}

What reflects MAP on the arterial waveform?

Answer 17

Area under the curve

Question 18

_{INTERPRETING ARTERIAL WAVEFORM}

How is Pulse pressure calculated?

What is its normal value?

Answer 18

PP = SBP - DBP

Normal value: 40 - 60 mmHg

Question 19

_{INTERPRETING ARTERIAL WAVEFORM}

Which informations could be gathered via Pulse Pressure?

Answer 19

Fluid status and Vascular competence

_{Via SV, CO, and SVR}

Question 20

_{INTERPRETING ARTERIAL WAVEFORM}

What could a Narrow PP (less than 40mmHg) indicate?

Answer 20

Hypovolemia

Cardiac tamponade

Anything that causes a low CO state

Question 21

_{INTERPRETING ARTERIAL WAVEFORM}

What could a Widened PP (more than 60mmHg) indicate?

Answer 21

Worsening aortic valve insufficiency

Usually Aortic Regurgitation

During diastole, the arterial BP will drop to backfill the LV through that regurgitant aortic valve that is supposed to be closed

May also get what’s called “Bisferiens pulse” which occurs d/t to run off of blood into the periphery and into the LV

Question 22

_{INTERPRETING ARTERIAL WAVEFORM}

What’s another name for the biphasic-pulse aortic waveform that shows two peaks per cardiac cycle, a small one followed by a strong and broad one? What does it indicate?

Answer 22

Bisferiens pulse

It is a sign of problems with the aortic valve, including aortic stenosis and aortic regurgitation, as well as hypertrophic cardiomyopathy causing subaortic stenosis

It is associated with a widened Pulse pressure

Question 23

_{INTERPRETING ARTERIAL WAVEFORM}

Explain the mechanics of Systolic Pressure Variation (SPV), volume status, and how it affects SBP?

Answer 23

PPV causes and increase in intrathoracic pressure which impedes VR, compresses the lungs, and causes blood in the pulmonary vasculature to be pushed to the left side of the heart, and ejected with each beat

This result in increase in BP during inspiration

During expiration, there is no augmentation to the amount of blood pumped out, resulting in a decrease in SBP

Question 24

_{INTERPRETING ARTERIAL WAVEFORM}

What’s the normal value of Systolic Pressure Variation (SPV)

Answer 24

10 mmHg

Question 25

_{INTERPRETING ARTERIAL WAVEFORM} What do large variations in Systolic Pressure Variation (\>15 mmHg) indicate? How do this affect ABP?

Answer 25

**Hypovolemia =** ↓ ABP with PPV Patients are said to be hypovolemic when the respiratory variations are more than 15mmHg. It’s the same exact concept as SVV (stroke volume variation) SVV is measured as percent

Question 26

_{INTERPRETING ARTERIAL WAVEFORM} What does the ARTERIAL WAVEFORM reflects?

Answer 26

Changes in pressures over time Qualitative estimates of hemodynamic indices of Contractility, SV, SVR

Question 27

_{INTERPRETING ARTERIAL WAVEFORM} On the following chart, what does "a" represents?

Answer 27

**Contractility** Grossly judged by rate of pressure rise/slope of upstroke during systole The steeper the slope, the quicker the rise, the greater the contractile forces Converly, the shallower the slope, the slower the rise and the weaker the contractile forces *This is a controversial way to the determine the pt's volume status*

Question 28

_{INTERPRETING ARTERIAL WAVEFORM} On the following chart, what does "b" represents?

Answer 28

**Stroke Volume** Area under the aortic pressure waveform Onset of systole to _dicrotic notch_

Question 29

_{INTERPRETING ARTERIAL WAVEFORM} What determines the location of the Dicrotic notch?

Answer 29

Timing of the Aortic closure in the cardiac cycle

Question 30

_{INTERPRETING ARTERIAL WAVEFORM} What charaterizes Aortic closure and dicrotic notch location in pts that are hypovolemic?

Answer 30

Aortic closure occurs slower Consequently the Dicrotic notch occurs farther down the dicrotic limb

Question 31

_{INTERPRETING ARTERIAL WAVEFORM} Why is using arterial waveform interpretation alone to determine volume status controversial?

Answer 31

*The location of the arterial line itself affects where the Dicrotic nocth occurs on the dicrotic limb* Pts with radial arterial line or arterial lines that are more peripheral will have their Dicrotic nocth occur lower on the dicrotic limb vs pts with arterial lines placed more proximal (axillary or sunclavian arteries or aortic root) This is why you cannot necessarily use the location of the Dicrotic notch to determine volume status

Question 32

_{INTERPRETING ARTERIAL WAVEFORM} What on the arterial waveform represents Systemic Vascular resistance?

Answer 32

Position of Dicrotic notch ## Footnote * High on downslope = ↑ SVR* * Low on downslope = ↓ SVR*

Question 33

_{INTERPRETING ARTERIAL WAVEFORM} What value of SVR correspond to a Dicrotic notch High on downslope?

Answer 33

↑ SVR

Question 34

_{INTERPRETING ARTERIAL WAVEFORM} What value of SVR correspond to a Dicrotic notch Low on downslope?

Answer 34

↓ SVR

Question 35

_{INTERPRETING ARTERIAL WAVEFORM} What does the "c" on the chart represents?

Answer 35

**Systolic time**

Question 36

_{INTERPRETING ARTERIAL WAVEFORM} What does the "d" on the chart represents?

Answer 36

**Diastolic time**

Question 37

_{ARTERIAL BP - SITES OF CANNULATION} Why is the Radial artery the most common cannulation site?

Answer 37

Ease of placement Accurate estimation of true aortic pressure

Question 38

_{ARTERIAL BP - SITES OF CANNULATION} What are contraindications for radial arterial line placement?

Answer 38

Positive Allen’s test Radial artery harvest

Question 39

_{ARTERIAL BP - SITES OF CANNULATION} Why is the Allen’s test performed before radial artery line placement?

Answer 39

Too determine whether ulnar artery collateral circulation to the hand is present in the case of arterial thrombosis The test screens for pts with inadequate palmar collateralisation from the ulnar artery

Question 40

_{ARTERIAL BP - SITES OF CANNULATION} How is the Allen’s test performed?

Answer 40

Apply firm pressure over both the radial and ulnar arteries simultaneously while having the pt squeeze their hand to promote exanguination Release pressure over the ulnar artery, keeping the radial artery compressed Measure time for capillary refill of the nail bed

Question 41

_{ARTERIAL BP - SITES OF CANNULATION} What is a _positive_ **Allen's test**? What does a positive Allen's test indicate?

Answer 41

Capillary refill of nail bed **\>10 seconds** Indicates inadequate collateral circulation from the ulnar artery

Question 42

_{ARTERIAL BP - SITES OF CANNULATION} Why should the radial artery line be placed in opposite side if the IMA is to be harvested for graft?

Answer 42

Due to the **dampen** or **obliterate tracing** resulting from compression of chest wall & subclavian artery _{This slide states that if the IMA is to be harvested for grafting, the radial artery catheter should be placed on the opposite side. This is not practice that you will see. The main reason that the surgeon request that the radial artery catheter be placed on one side over the other is if he plans to harvest the radial artery for one of the bypass grafts. OR if there is some type of blockage in the subclavian that would preclude you from placing a catheter in it and reducing blood flow even more. And the reason is because of compression of the chest wall with the sternal retractor. However, this is not actual practice that you will see, although it theoretically could happen because the internal mammary arteries branch off the subclavian artery proximal to where the subclavian becomes the axillary artery. Here you can see the right subclavian artery and how the internal thoracic or internal mammary artery branches off the subclavian artery. This picture shows it branching off the axillary because the subclavian actually turns into the axillary artery as it passes underneath the clavicle. So theoretically, you could have an obliteration of the pulse with the sternal retractor that’s used to take down the mammary.}

Question 43

_{ARTERIAL BP - SITES OF CANNULATION} Where should the arterial line be placed if both IMA’s are to be harvested?

Answer 43

F**emoral artery**

Question 44

_{ARTERIAL BP - SITES OF CANNULATION} Why is the use of the Brachial artery relatively contraindicated as a cannulation site?

Answer 44

Brachial artery has **no benefit of collateral flow** as does the ulnar _{Brachial artery (medial to the antecubital fossa)}

Question 45

_{ARTERIAL BP - SITES OF CANNULATION} In which instances is Brachial artery cannulated?

Answer 45

Invasive BP monitoring is required, but Radial arteries cannot be cannulated for some reason

Question 46

_{ARTERIAL BP - SITES OF CANNULATION} True or False: Brachial arterial line are usually only used for short periods of time

Answer 46

True

Question 47

_{ARTERIAL BP - SITES OF CANNULATION} Why does Brachial arterial line more accurately reflects central aortic pressure than the radial artery?

Answer 47

C**loser to the heart**

Question 48

_{ARTERIAL BP - SITES OF CANNULATION} Why should shortest, smallest gauge (18 or less) cath be used for Brachial artery line cannulation?

Answer 48

To decrease the incidence of **thromboembolism**

Question 49

_{ARTERIAL BP - SITES OF CANNULATION} What's the largest vesselcommonly use to monitor arterial BP with comparable results to all other sites?

Answer 49

**Femoral artery** *Large & superficial making for easy access*

Question 50

_{ARTERIAL BP - SITES OF CANNULATION} Why is the Femoral artery an excellent access to the central arterial tree?

Answer 50

Its waveform more closely resemble aortic pressure waveform than do waveforms from more peripheral sites

Question 51

_{ARTERIAL BP - SITES OF CANNULATION} Why is there a Low risk of distal ischemic sequela with femoral artery cannulation?

Answer 51

Because of its large **Diameter**

Question 52

_{ARTERIAL BP - SITES OF CANNULATION} When is the risk for plaque immobilization and pseudoaneurysm significant with femoral artery line placement?

Answer 52

When initially placing the line

Question 53

_{ARTERIAL BP - SITES OF CANNULATION} Why should the femoral artery be placed below the inguinal line?

Answer 53

To reduce the risk of damaging the **inguinal liguament**

Question 54

_{ARTERIAL BP - SITES OF CANNULATION} True or False: during femoral cannulation, you must be cautious of hitting a hematoma or creating uncontrolled hematomas into the pelvis or retroperitoneal space

Answer 54

**True**

Question 55

_{ARTERIAL BP - SITES OF CANNULATION} Why femoral artery cannulation suggested in pts with expected difficulty weaning from CPB d/t known ↓ EF or severe wall motion abnormalities?

Answer 55

They may require IABP Access may be used should IABP placement become necessary

Question 56

_{ARTERIAL BP - SITES OF CANNULATION} What are contraindications to femoral artery cannulation?

Answer 56

Prior vascular surgery Skin infection

Question 57

_{ARTERIAL BP - SITES OF CANNULATION} What are advantages of Axillary artery cannulation?

Answer 57

More comfortable for the patient Large and superficial Easy access to central arterial tree Provides a central arterial pressure waveform that more closely resemble the aortic root pressure

Question 58

_{ARTERIAL BP - SITES OF CANNULATION} Why is there increased risk of cerebral embolus of air or debris with axillary artery cannulation?

Answer 58

Because cannulation site more centrally located Air or debris can easily enter the circulation during flushing of the catheter

Question 59

_{ARTERIAL BP - SITES OF CANNULATION} Why is left axillary cannulation preferred?

Answer 59

Reduce risk of cerebral embolus of air or debris

Question 60

_{ARTERIAL BP - SITES OF CANNULATION} What could cause nerve damage with axillary catheter placement?

Answer 60

Hematoma formation Traumatic cannulation

Question 61

_{ARTERIAL BP - SITES OF CANNULATION} True or False: Infection at site is a contraindication for axillary artery cannulation

Answer 61

True

Question 62

_{ARTERIAL BP - SITES OF CANNULATION} When is Aortic root cannulation indicated for arterial BP monitoring? Who places it?

Answer 62

When difficulties are encountered in obtaining reliable BP Placed by surgeon

Question 63

_{ARTERIAL BP - SITES OF CANNULATION} Ulnar artery cannulation is rare. The Process for cannulation of the ulnar artery is similar to that of which other vessel?

Answer 63

The radial artery

Question 64

_{ARTERIAL BP - SITES OF CANNULATION} True or False: Ulnar artery provides most of the blood flow to the hand in 90 percent of pt

Answer 64

True

Question 65

_{ARTERIAL BP - SITES OF CANNULATION} In which instances is the ulnar artery cannulated?

Answer 65

When radial artery can not be used Positive Allen’s Harvest for graft

Question 66

_{ARTERIAL BP - SITES OF CANNULATION} Allen's test must be performed prior to ulnar catheter placement. How does Allen's test for ulnar artery cannulation differ to that for radial artery cannulation?

Answer 66

*Occlude the ulnar artery* and assess for adequate radial artery collateral flow

Question 67

_{ARTERIAL BP - SITES OF CANNULATION} What are disadvantages of using Dorsalis pedis and posterior tibial arteries as cannulation sites for BP monitoring?

Answer 67

Difficult management in postop period Difficult cannulation Increased risk for ischemic complications Relative contraindication with PVD/DM Distal location increases distortion of waveform

Question 68

_{ARTERIAL BP - SITES OF CANNULATION} In which population is it appropriate to use Dorsalis pedis and posterior tibial arteries as cannulation sites?

Answer 68

Pediatrics

Question 69

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, what happens to **Arterial upstroke**?

Answer 69

Becomes **steeper**

Question 70

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, what happens to **Systolic peak**?

Answer 70

Becomes **higher**

Question 71

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, when does the **Dicrotic notch** appears?

Answer 71

**Later!!!**

Question 72

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, what happens to **Diastolic wave**?

Answer 72

Becomes more prominent

Question 73

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, what happens to **End diastolic pressure**?

Answer 73

Becomes lower

Question 74

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, what happens to **Systolic pressure**?

Answer 74

Systolic pressure increases (as much as **20-50mmHg higher** than central aorta)

Question 75

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, what happens to **Diastolic pressure**?

Answer 75

Becomes lower

Question 76

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, what happens to **Pulse pressure**?

Answer 76

Wider pulse pressure

Question 77

_{Direct Arterial Blood Pressure} As cannulation site becomes more peripheral, what happens to **MAP**?

Answer 77

MAP remains relatively unchanged

Question 78

_{ARTERIAL BLOOD PRESSURE MONITORING - COMPLICATIONS} What are common complications associated with arterial blood pressure monitoring?

Answer 78

Distal ischemia (low) Arterial thrombosis Infection Bleeding

Question 79

_{ARTERIAL BLOOD PRESSURE MONITORING - COMPLICATIONS} What's is the most common site of arterial BP cannulation for CPB?

Answer 79

The radial artery

Question 80

_{ARTERIAL BLOOD PRESSURE MONITORING - COMPLICATIONS} Sometimes, False low of radial artery pressure is seen immediately after CPB. What could be responsible of lower BP immediately after CPB?

Answer 80

Peripheral vasodilation secondary to rewarming Hypovolemia Vasoconstriction *_{If suspect that peripheral artery tracing is dampened (slow upstroke or loss of dicrotic notch), obtain a direct pressure measurement from central site}*

Question 81

_{ARTERIAL BLOOD PRESSURE MONITORING - COMPLICATIONS} Sometimes, False low of radial artery pressure is seen immediately after CPB. What would the surgeon do if this is suspected?​

Answer 81

The surgeon will sometimes place a catheter into the aortic root and transduce it to compare it to the radial artery pressure And if it is in fact lower, an alternate site will be chosen to place an arterial line

Question 82

_{RECOMMENDATIONS FOR BLOOD PRESSURE MONITORING DURING CPB} T/F: Radial artery pressure is usually accurate before and after CPB

Answer 82

True

Question 83

_{RECOMMENDATIONS FOR BLOOD PRESSURE MONITORING DURING CPB} When is Addition of a femoral artery catheter recommended?

Answer 83

Poor LV function is evident Second comparable (central) BP ^{(BP from a more peripheral site is questionable)} Ensures arterial access should IABP become necessary

Question 84

_{RECOMMENDATIONS FOR BLOOD PRESSURE MONITORING DURING CPB} If IMA is to be harvested for grafting, why should you place radial artery catheter in opposite side

Answer 84

Compression of chest wall/subclavian artery =\> dampens/obliterates tracing This is not necessarily practice Theoretically, because the IMA branches from the SC artery, occlusion could occur to the radial artery This is rarely seen unless the pt has some sort of blockage in the sc artery

Question 85

_{RECOMMENDATIONS FOR BLOOD PRESSURE MONITORING DURING CPB} If both IMA’s are to be harvested, where should the arterial cannulation be placed?

Answer 85

Place femoral artery catheter

Question 86

_{RECOMMENDATIONS FOR BLOOD PRESSURE MONITORING DURING CPB} If radial artery to be harvested, where should you place arterial line?

Answer 86

Place radial arterial line on **opposite side**

Question 87

_{RECOMMENDATIONS FOR BLOOD PRESSURE MONITORING DURING CPB} When is the only time that the radial artery is cannulated on the opposite side?

Answer 87

Known blockage in the subclavian artery Radial artery is to be harvested