Mod1: Monitoring for Cardiac Surgery - RENAL FUNCTION - NEUROLOGIC OUTCOME

Question 1

_INDICATIONS

Acute kidney injury (AKI) is a prevalent complication following bypass surgery. How often does it occur? What factor influences its occurence?

Answer 1

15-30%

Occurrence depends on complexity of procedure

Question 2

_INDICATIONS

What percentage of cardiac surgery pts suffer Dialysis dependent AKI? What’s it mortality rate?

Answer 2

2-5% of cardiac surgery patients

Dialysis dependent AKI carries mortality rate of 50%-80%

Associated with significant increase in hospital costs

Question 3

_INDICATIONS

Which three things is the renal failure resulting from impaired renal oxygenation that occurs during bypass is thought to be independently associated with?

Answer 3

Renal vasoconstriction

Hemodilution during cardiopulmonary bypass with cell-free solutions (e.g., crystalloids)

Non-physiologic state of nonpulsatile flow upsets renal blood flow autoregulation

Question 4

_INDICATIONS

T/F: Studies have shown that even with maintaining a mean perfusion pressure of 50 to 75, which has been shown to be adequate for maintaining systemic oxygen delivery, there is still a redistribution of blood away from the kidneys that occurs with bypass

Answer 4

True

Question 5

_INDICATIONS

T/F: During bypass, kidney function as well as kidney oxygen requirements are reduced?

Answer 5

False

Kidney function during bypass is maintained, as well as its oxygen requirements

Question 6

_INDICATIONS

During bypass, renal oxygen delivery is reduced by 20%. What’s responsible for this?

Answer 6

The combination of normal oxygen demand with reduced oxygen supply

Question 7

_INDICATIONS

What’s a negative outcome of the use of diuretics in CPB (e.g., mannitol)?

Answer 7

Hemolysis may occur

Question 8

_INDICATIONS

Why must U/O be maintained during CPB, especially when diuretics are used?

Answer 8

To avoid renal tubule damage

Removal of excess free water due to deliberate hemodilution induced with onset of CPB

Question 9

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

Which neurologic complications occur following adult cardiac surgery?

Answer 9

Stroke 1-3%

Encephalopathy

Cognitive dysfunction

_{Etiology of these complications is complex, but multifactorial}

Question 10

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

T/F:

There is a statistically significant difference in occurence of neurologic complications between patients who have undergone on pump bypass vs off pump bypass surgeries

Answer 10

False

There is No statistically significant difference between patients who have undergone on on pump bypass vs off pump bypass surgeries

Question 11

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

Which neurologic complication affect more patients than all other neurologic complications?

Answer 11

Cognitive dysfunction

Question 12

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

T/F:

Cognitive dysfunction is more prevalent at 1 month vs at 6 months after surgery

Answer 12

True

30-65% patients affected at 1 month

20-40% patients affected at 6 months

Question 13

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

What are possible causes of neurologic complications during CPB?

Answer 13

Cerebral emboli

Global cerebral hypoperfusion

Systemic inflammatory response

Genetic predisposition

Question 14

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

Microemboli responsible for Cerebral emboli during CPB are of which two types?

Answer 14

Gasses or particulates

Question 15

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

Where do Macroemboli responsible for Cerebral emboli during CPB originate?

Answer 15

Atheromatous

Calcific debris from the aorta

Cardiac valves

Great vessels

Question 16

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

We’ve discussed the importance of cerebral protection during CPB, and the importance of cooling and rewarming during the various phases of bypass.

What are indications for CNS monitoring?

Answer 16

Known diagnosis of cerebral ischemia or one that develops during the course of the procedure

Assess depth of anesthesia which is very important during the rewarming phase (prevent intraoperative awareness)

Spinal cord protection (thoracic aneurysm repair)

To confirm adequate cooling/hypothermic arrest

• Pre-existing neurologic disease*
• Diagnosis of embolic phenomenon*

Question 17

_{NEUROLOGIC OUTCOME FOLLOWING CARDIAC SURGERY}

Which adverse neurologic outcome could come from inadequate arterial flow on CPB or Aortic cannula malposition during CPB?

Answer 17

Cerebral ischemia

Question 18

_{ELECTROENCEPHALGRAM}

What does the EEG reflects?

Answer 18

The EEG reflects metabolic activity of the brain

Question 19

_{ELECTROENCEPHALGRAM}

Why is the EEG rarely used during cardiac surgery to confirm the adequacy of cerebral oxygenation?

Answer 19

Because there are simpler methods for monitoring

Question 20

_{ELECTROENCEPHALGRAM}

What does the EEG records?

Answer 20

The electrical activity of cells in the cerebral cortex

Question 21

_{ELECTROENCEPHALGRAM}

Which EEG waves are often found in the resting adult with eyes closed?

Answer 21

Alpha waves

Frequency: 9-12Hz

Explanation: Medium frequency, higher amplitude, awake but eyes closed (EEG seen in occipital lobes)

Question 22

_{ELECTROENCEPHALGRAM}

Which EEG waves are found in concentrating adults, and sometimes in adults undergoing anesthesia?

Answer 22

Beta waves

Frequency: 13-30Hz

Explanation: High frequency, low amplitude, awake state

Question 23

_{ELECTROENCEPHALGRAM}

Which EEG waves are found with brain injury, deep sleep and anesthesia?

Answer 23

Delta waves

Frequency: 0-4Hz

Explanation: Very low frequency, depressed functions (coma, deep anesthesia, hypoxia, ischemia, infarction, poor metabolism)

Question 24

_{ELECTROENCEPHALGRAM}

Which EEG waves are found in sleeping individuals and those undergoing anesthesia?

Answer 24

Theta waves

Frequency: 4-8Hz

Explanation: Low frequency, seen under general anesthesia

Question 25

_{ELECTROENCEPHALGRAM}

What does slowing of electrical brain activity and decrease in signal amplitude on EEG indicate?

Answer 25

Cerebral ischemia

Question 26

_{ELECTROENCEPHALGRAM}

T/F: EEG requires experienced personel to interpret data

Answer 26

True

Question 27

_{BIS MONITOR}

What is BIS monitor indicated and used for?

Answer 27

Commonly used to indicate wakefulness

Used to measure the depth of anesthesia

More easily interpreted and utilized

Question 28

_{BIS MONITOR}

Why can’t BIS monitor be used to assess global ischemia?

Answer 28

Because the monitor is placed on the forehead

Question 29

_{BIS MONITOR}

T/F: BIS is a type of processed EEG

Answer 29

True

Question 30

_{BIS MONITOR}

In BIS power spectrum analysis how is EEG data processed?

Answer 30

By Fast Fourier Analysis …

into a single power versus time spectral array

Data reduced via proprietary method to a single number and scaled

Question 31

_{BIS MONITOR}

What does a BIS number of 100 indicate?

Answer 31

Alert/wakefulness

Question 32

_{BIS MONITOR}

What does a BIS number of 90-70 indicate?

Answer 32

Light to moderate sedation

Question 33

_{BIS MONITOR}

What does a BIS number of 70-60 indicate?

Answer 33

Deep sedation

Low probability of explecit recall

Question 34

_{BIS MONITOR}

What does a BIS number of 60-40 indicate?

Answer 34

General or adequate depth of Anesthesia

Question 35

_{BIS MONITOR}

What does a BIS number of 40-10 indicate?

Answer 35

Deep hypnotic state

Question 36

_{BIS MONITOR}

What does a BIS number of 10-0 indicate?

Answer 36

Flat line on the EEG

Electrical silence

Question 37

_{EVOKED POTENTIALS}

In which surgical cases do monittoring Somatosensory (SSEPs) & Motor evoked potentials (MEPs) become very important?

Answer 37

In cases where maintaining spinal cord blood flow is crucial

SSEPs and MEPs are used to monitor integrity of spinal cord during surgery of the descending aorta (thoracic aneurysm where blood flow to spinal cord may be compromised)

Question 38

_{EVOKED POTENTIALS}

Why do many of the thoracic aneurysm cases hold a very high incidence of paraplegia?

Answer 38

Incrased risk of hypoperfusion of the spinal cord following surgery

Question 39

_{EVOKED POTENTIALS}

How are Evoked Potentials measured?

Answer 39

A stimulus is applied to peripheral nerve while the brain activity is quantified

Question 40

_{EVOKED POTENTIALS}

What are the two different methods of assesing Evoked Potentials?

Answer 40

Visual evoked potentials

Brain stem audio evoked potentials

Question 41

_{EVOKED POTENTIALS}

T/F: Evoked Potentials Do not have routine clinical application in cardiac surgery

Answer 41

True

Question 42

_{CEREBRAL OXIMETRY}

Cerebral oximetry is increasingly used in the perioperative period of cardiac surgery. What technology does is use?

Answer 42

Infrared spectroscopy (NIRS)

It is a noninvasive technology that monitor the regional oxygen saturation of the frontal cortex

Question 43

_{CEREBRAL OXIMETRY}

What’s a benefit of the preoperative use of cerebral oximetry?

Answer 43

Can stratify patients preoperatively according to their risk

Question 44

_{CEREBRAL OXIMETRY}

What are benefits of using cerebral oximetry Intraoperatively?

Answer 44

Continuous information about brain oxygenation

Allows the use of the brain as an organ that indexes overall organ perfusion and injury

Question 45

_{CEREBRAL OXIMETRY}

What’s the similarity of cerebral oximetry with pulse ox?

Answer 45

Oxygenated and deoxygenated hemoglobin absorb light at different frequencies

Question 46

_{CEREBRAL OXIMETRY}

Unlike pulse oximetry, cerebral oximetry cannot identify pulsatile arterial components. Why not?

Answer 46

Because it reflects absorption of venous hemoglobin

Question 47

_{CEREBRAL OXIMETRY}

What are normal ranges of cerebral oximetry prior to anesthesia?

Answer 47

60-80%

Lower values of 50-60% have been seen

Question 48

_{CEREBRAL OXIMETRY}

What might regional saturation less than 40% or changes from baseline greater than 25% indicate

Answer 48

Neurological events secondary to decreased cerebral oxygenation

It’s important however to make sure that Pre-sedation values are captured to make accurate comparison with the post-sedation values

Question 49

_{CEREBRAL JUGULAR BULB VENOUS OXIMETRY}

What does jugular bulb venous oximetry monitor?

Answer 49

Cerebral metabolic function

Question 50

_{CEREBRAL JUGULAR BULB VENOUS OXIMETRY}

How does jugular bulb venous oximetry measure cerebral metabolic function?

Answer 50

Via fiberoptic catheter

Akin to measuring SVO2 via PA catheter

Question 51

_{CEREBRAL JUGULAR BULB VENOUS OXIMETRY}

Why is jugular bulb venous oximetry not routinely used in cardiac surgery?

Answer 51

Because of it invasiveness, and

Less invasive monitors are available

Question 52

_{CEREBRAL JUGULAR BULB VENOUS OXIMETRY}

What factors influence Cerebral O2 consumption?

Answer 52

Cerebral blood flow

O2 extraction from brain

Question 53

_{CEREBRAL JUGULAR BULB VENOUS OXIMETRY}

How does Decreased cerebral blood flow affect jugular O2 saturation?

Answer 53

Decreased cerebral blood flow => Increases O2 extraction

=> Decrease jugular O2 saturation

Question 54

_{CEREBRAL JUGULAR BULB VENOUS OXIMETRY}

T/F: Trend monitoring yields more info than individual measurements

Answer 54

True