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Perf tech II > test 5 part 2 > Flashcards

test 5 part 2 Flashcards

1
Q

When delivering CPG, you need a what

A
  • PRESSURE
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2
Q

ways of measuring pressure

A

š- Direct measurement
š *Measured directly at the site
-š Calculated Measurement
š *Pressure drop calculation

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3
Q

Pressure Drop

A
  • Decrease in pressure from one point in a tube to another point downstream
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4
Q

Pressure Drop and Delivery of Cardioplegia

A
  • Pressure drop Occurs with frictional forces on a fluid as it flows through a tube
    š *Resistance (velocity and viscosity) = increase in resistance increases pressure drop
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5
Q

Pressure Drop in relation to shear forces

A

-š Increases proportional to frictional shear forces
š *High flow velocities and / or high fluid viscosities -> Larger pressure drops
š *Low velocity -> lower / no pressure drop

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6
Q

Goal for perfusionist and what we look at when monitoring effectiveness

A

-š Want to optimize uniformity and effectiveness of delivery
š *Especially retrograde
- Look at electrical activity and temperatuer

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7
Q

Monitoring - Temperature

A 
- Myocardial Temperature
š *Thermo coupled needle inserted septal muscle
-š Ensure delivery of adequate dose
-š Efficacy of delivery
š *Cases of aortic insufficiency
š *Retrograde (cannula position)
-š Determine when next dose needed
š **YOU ARE THE TIMEKEEPER!!!
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8
Q

Types of Setups

A 
š- Crystalloid (custodial)
š *Single pass system
š- Blood
š -Fixed ratio
š *Bridged
š *Non-Bridged
š- Microplegia
š *MPS
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9
Q

Crystalloid Cardioplegia benefits

A 
š- Simple
š- Inexpensive
š- Readily available
š- Better surgical visibility
š- Lower viscosity – better distal perfusion
š- Low calcium (promotes quiescence)
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10
Q

Crystalloid Cardioplegia disadvantages

A 
-š No beneficial effect on metabolic environment
š *Minimal buffering
-š Minimal oxygen carrying capacity
š- Hemodilution due to large volumes
- Must be delivered coldš 
- Low oxygen carrying capacity
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11
Q

Blood Cardioplegia 2:1, 4:1, 8:1, 16:1 ratios (blood:crystalloid) benefits

A 
-š Improves metabolic
environment
š *Oxygen and substrates
š *Trace elements (such as magnesium) for ATP production
š *Natural buffers
š *Natural oncotic pressures (prevents edema)
š *Free radical scavengers!!!
-š Can be delivered warm
-š Smaller crystalloid volume
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12
Q

Blood Cardioplegia 2:1, 4:1, 8:1, 16:1 ratios (blood:crystalloid) disadvantages

A
  • Shifts the oxy-hemoglobin dissociation curve to the left
  • š Increased viscosity
  • š Complexity
  • š Cost
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13
Q

Blood vs. Crystalloid

A
  • blood cardioplegia enhanced aerobic myocardial metabolism during aortic cross-clamping
    š - increased myocardial oxygen consumption
    š - reduced anaerobic lactate production
    š - preserved high-energy phosphate stores
    -š Blood cardioplegia also improved both systolic and diastolic function following surgery
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14
Q

Current consensus for Blood vs. Crystalloid

A
  • šBlood cardioplegia is superior in terms of myocardial protection and recovery.
    š- There may be no long-term difference in outcomes using blood vs. crystalloid cardioplegia.
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15
Q

Microplegia (Quest MPS)

A

-š Type of blood cardioplegia
š *Very small volume of crystalloid (instead of 4:1, 8:1, 16:1, etc)
-š Independent control of blood:crystalloid ratio as well as arresting agents and additives
-š Eliminates crystalloid solutions
š *Reduces edema
- Cons: cost and complexity

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16
Q

Temperature of CPG

A 
- Standard temperature = 10°C
š *Blood cardioplegia
š *Crystalloid Cardioplegia
-š Topical Jacket or Saline Flush
š *Aid in myocardial cooling
š *May cause phrenic nerve damage
-š Target myocardial temperature is 10-15ºC.
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17
Q

Delivery temperature study

A

-š Postoperative left ventricular function was greatest with warm, intermediate with tepid, and least with cold cardioplegia

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18
Q

Intermittent Delivery pros

A

-š Improved exposure

š- Lower cardioplegia volume delivered

19
Q

Intermittent Delivery cons

A
  • Increased inter-dose myocardial acidosis
20
Q

Continuous Delivery pros

A
  • š Normal perfusion
  • š Increased post-operative LV performance
  • š Decrease inotrope requirement
21
Q

Continuous Delivery cons

A
  • š Operative field may not be “dry”

- š Complexity for surgeon and perfusionist

22
Q

purpose of KCl as an additive

A
  • Produce / maintain diastolic arrest
23
Q

purpose of THAM/ histadine as an additive (similar to bicarb)

A
  • Buffer

- decreases acidosis and brings up pH

24
Q

purpose of mannitol as an additive

A
  • Osmolarity, free radical scavenger
25
Q

purpose of Aspartate / glutamate as an additive

A
  • Metabolic substrate
  • gives cells a substrate to use
  • EXPENSIVE
26
Q

purpose of MgCl2 as an additive

A
  • Mitigates against calcium

- helps maintain homeostasis of the cells

27
Q

purpose of CPD as an additive

A
  • Lowers free calcium

concentration

28
Q

purpose of Glucose as an additive

A
  • Metabolic substrate
29
Q

purpose of Blood as an additive

A
  • Oxygen-carrying capacity, etc.
30
Q

Typical Cardioplegia

A 
Before dilution with blood:
 *Potassium Chloride – 100 mmol/L
š *THAM – 12 mmol/L
š *Magnesium sulfate – 9 mmol/L
š *Dextrose – 250 mmol/L
š *CPD-Adenine – 20 mL
31
Q

St. Thomas Solution

A 
š *Sodium – 110 mmol/L
š *Potassium – 16 mmol/L
š *Calcium – 1.2 mmol/L
š *Magnesium – 16 mmol/L
š *Chloride – 160 mmol/L
š *Sodium Bicarbonate – 10 mmol/L
š *Osmolarity – 320 mOsm/L
32
Q

Custodial HTK

A

š- Histadine – Tryptophan – Ketogluterate
-š Intracellular cardioplegia solution (similar to intracellular conditions)
š *Low sodium concentration
š *Histidine
š *Tryptophan
š *Mannitol
-š Longer safe time of ischemia

33
Q

Del Nido Cardioplegia (1:4)

A
  • Plasmalyte base – similar to ECF (1000 mL)
34
Q

Three Phases of Cardioplegia

A

-š Induction of Arrest
š- Maintenance of Arrest
š- Reperfusion

35
Q

Induction

A

-š Pure Crystalloid Induction
š *Easy, Cheap, Low Viscosity
š *Edema, low O2, Hemodilution
-š Cold Blood Cardioplegia Induction
š *Oxygen, decreased hemodilution, buffering, oncotic effects, endogenous scavengers
*sludging and RBC damage from occluded roller pumps
-š Warm Blood Cardioplegia Induction
š *Improved aerobic metabolism, improved LV function,
š *Expensive additives (GA)

36
Q

Potassium Blood CPG maintenance

A

-š Lower potassium
-š Usually every 15-20 minutes
š *After grafts
-š Restores arrest
š *Post wash-out of metabolites

37
Q

Warm Continuous Retrograde Blood Cardioplegia maintenance

A

-š Warm retrograde cardioplegia flow must be >100ml/min to minimize myocardial lactate production

38
Q

Hot Shots

A

-š Warm retrorade blood cardioplegia
-š Given just prior to cross-clamp removal
š *Warm Heart
š *Better metabolic environment
- slowly getting the patient ready

39
Q

Hot shots types

A
  • š Warm blood only

- š Substrate enhanced blood cardioplegia

40
Q

Preparation for Reperfusion

A

-š Substrate enhanced cpg
š- Limit calcium
š- Limit pO2
š- Controlled reperfusion
*Endothelium damaged during ischemia
š *Can be worsened through unregulated perfusion
š *After AoXC removal – 40mmHg for 1-2 min
š *70mmHg after 2 min
-š Adequately deair
-š Avoid ventricular distension (venting)

41
Q

Fibrillatory Arrest

A
  • š Place an alternating current generator in contact with LV
  • š L side of heart opened without fear of ejection
  • š Used with hypothermia
  • Spontaneous ejection – air emboli!!
  • used for really quick cases
  • closing a PFO or an ASD or a very small myxoma
42
Q

Fibrillatory Arrest advantages

A
  • Avoid XC

- š ”Quiet” heart with coronary perfusion

43
Q

Fibrillatory Arrest disadvantages

A
  • High energy requirement
44
Q

Off Pump

A
  • Regional Ischemia unavoidable
  • Ischemic pre-conditioning
  • š Keep normal to high systemic blood pressure
  • Adequate coronary perfusion / flow through collateral vessels
  • š ATTACH PROXIMAL END OF GRAFT BEFORE DISTAL
  • Immediate re-estabilishment of blood flow
  • š Use intracoronary shunt

Perf tech II (16 decks)

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