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AS - N934 Advanced Principles II > Cardiac Anesthesia > Flashcards

Cardiac Anesthesia Flashcards

1
Q

Preop Evaluation

A

Cardiac history - disease severity & hemodynamic status
- EKG, stress ECHO, cardiac catheterization
- Baseline status (EF, LVEDP, pulmonary HTN, valvular or congenital lesions, CHF)
Past surgical history - previous sternotomy (scarring), vascular surgery, graft sites, or Protamine administration
Angina presentation
Dysrhythmias
METs (exercise tolerance)
Past medical history - TIA or CVA (carotid studies before CV surgery to preserve CBF)
Comorbidities: HTN, COPD, T2D (infection risk), vascular disease, renal or liver insufficiency
Medications - anticoagulants, antianginal, β blockers, insulin, ACEi, ARBs

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2
Q

What’s the mortality percentage after an intraop MI?

A

50%

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3
Q

Cardiac Catheterization

A

Locates potential blockage(s)

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4
Q

EKG

A

Recent MI

Assess rate & rhythm

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5
Q

ECHO

A 
EF %
Valve function
Wall abnormalities
Aorta calcification
Atrial thrombus
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6
Q

Coagulation Studies

A

PTT/PT
Baseline ACT
Platelet number & functionality
TEG (thromboelastogram)

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7
Q

Chest X-ray

A

Aorta calcification
Cardiomegaly
Edema

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8
Q

Renal Function

A

Decreased function ↑postop mortality

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9
Q

Liver Function

A

Cardio-pulmonary bypass ↓liver perfusion

↑hypoperfusion risk d/t ↓splanchnic flow on CPB

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10
Q

What medications to continue leading up to cardiac surgery?

A

Antiarrhythmics
Ca2+ channel blockers
β blockers
Nitrates

Ø antiplatelet/anticoagulants

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11
Q

Cardiac Anesthesia Goals

A
  1. ↓cardiac oxygen utilization (MVO2)
  2. Maintain O2 supply
  3. Anticoagulation
  4. Normotensive w/in 20% baseline
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12
Q

↓MVO2

A

Anesthesia ↓SNS
Hypothermia - alters platelet function & ↓fibrin enzyme function, inhibits thrombin formation, & ↓metabolic demand, ↑ischemia tolerance
Cardioplegia K+ continuous admin during cross-clamping → electrical & mechanical activity ceases (renal patients hyperkalemia)
Empty cardiac chambers Ø LV distension

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13
Q

Maintain O2 Supply

A

Maximize O2 carrying capacity & flow
Optimal Hgb/Hct 30%
Hemodilution (dilutes clotting factors) = less viscous ↓blood viscosity ↑flow
Acceptable perfusion pressures & flow

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14
Q

Hypotension

A

↓end-organ perfusion

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15
Q

Hypertension

A

Disrupt myocardial balance

↑MVO2 (demand)

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16
Q

Monitoring

A

Pox
NIBP + A-line
EKG (ensure correct placement especially leads II & V5)
Temp probe (Foley best site for core temp w/ less impact from cooling, but delayed reading)
Foley
CVP or PA cath
NIRS/BIS on before induction to provide baseline
TEE

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17
Q

Transesophageal Echo

A

Evaluate preload (ventricular filling)
Volume status
Estimate CO
Assess ventricular systolic/diastolic function
Valvular pathology
Aorta calcifications
Cardiac tamponade
Atrial thrombus
Assess air present in heart prior to closure → de-airing maneuvers
Anastomosis evaluation after patient off bypass

When to admin volume, start vasoactive gtts, re-examine graft, & assess surgical repair

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18
Q

TEE Contraindications

A 
Esophageal pathology (i.e. alcoholic varices)
Empty stomach before placing the probe
- After asleep place down OG to suction
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19
Q

Swan Ganz

A

Pulmonary artery catheter
Typically placed in the R IJ (most direct route)
Cordis placed after induction as introducer to float the PA through when needed
TEE > PA cath

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20
Q

PA Catheter Insertion

R Atrium

A

5mmHg

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21
Q

PA Catheter Insertion

R Ventricle

A

15-30 / 0-8

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22
Q

PA Catheter Insertion

Pulmonary Artery Normal Pressures

A

15-30 / 5-15 mmHg

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23
Q

PA Catheter Wedge Pressure (PAWP)

A

Reflects the L ventricle pressure
Dampened waveform
Balloon inflated & catheter wedged into pulmonary artery distal branch
= 10

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24
Q

Swan Ganz Complications

A

Ventricular arrhythmias
Heart block (especially in patient w/ pre-existing L bundle branch block)
Pneumothorax (most common w/ subclavian approach)
Unintended arterial puncture (most common acute injury)
Valve damage
Hematoma/thromboemoblism
Vascular injury (localized hematoma)
Thorax perforation → hemothorax
Pulmonary artery rupture → blood noted in ETT
Cardiac tamponade
Bloodstream infection

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25
Q

Aortic or Mitral Stenosis Valve Repair

A 
Maintain preload (volume)
Maintain SVR (afterload)
Lower HR < NSR 50-80bpm
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26
Q

Aortic or Mitral Regurgitation Valve Repair

A

Maintain preload (volume)
↓SVR
↑HR to promote forward flow & prevent regurgitation

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27
Q

Monitoring, Equipment, & Drugs (Infusions/Emergency)

A

Pacemaker
Infusions:
- Nitroglycerin or sodium nitroprusside
- Epi or NE
- Phenylephrine
- Dopamine/Dobutamine
- Antiarrhythmics (Esmolol, Lidocaine, Magnesium, Amiodarone)
- Insulin
Coagulation monitoring ACTs or TEG/ROTEM
Emergency drugs - Atropine, Glycopyrrolate, Ephedrine, Succinylcholine
Type & cross 4 units PRBCs available in OR

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28
Q

What neuromuscular blocking agent should be avoided in cardiac anesthesia? Why?

A

Pancuronium

Vagolytic ↑HR d/t reflex tachycardia

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29
Q

When to administer antibiotics?

A

Pre-incision & post bypass

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30
Q

What diagnoses fibrinolysis? When to start monitoring to be effective?

A

Thromboelastogram (TEG)

BEFORE going on CPB

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31
Q

Preop Anesthetic Considerations

How to prepare the patient for induction?

A

Oxygen via NC or non-rebreather
Limit or avoid Midazolam
Place lines before induction - PIV x2, A-line, CVP, PA catheter (after induction in stable patients)
Discuss access when surgical team regarding A-line & vein or graft harvesting sites
Obtain baseline ABG & ACT
Place external defibrillation (R2) pads on prior to induction

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32
Q

Intraop Anesthetic Considerations:

Positioning, Incision, & Temperature

A

Positioning - supine w/ arms tucked
Ensure lines infusing, A-line waveform present, & blood return +
Preop area from sternal notch to toes (saphenous vein graft)
Fluid warmer
Under-body forced air warmer
Rapid infuser available
Infusions set-up, programed, connected to the patient, & ready to go

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33
Q

Volatile Anesthetics

A

Dose-dependent cardiac depression
Negative effects d/t intracellular Ca2+ alterations
Sensitizes the myocardium to Epi
Prevent or facilitate atrial or ventricular arrhythmias during myocardial ischemia or infarction
Produces weak coronary artery dilation & depresses baroreceptor reflex control (arterial pressure)

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34
Q

Induction

A

Narcotics CV stable
- High dose
- Low dose w/ induction agent
Awake intubation when difficult airway anticipated
Post-induction place central line, OG, & TEE (stable patients when not placed pre-induction)

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35
Q

What to anticipate pre-incision?

A

Lack stimulation → HoTN
Systemic pressure support
Recall rare

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36
Q

Incision → Bypass

A

Sternotomy - drop the lungs
Discontinue or ↓pressors prior to sternotomy
Intense surgical stimulation w/ incision
HTN → deepen the anesthetic & consider vasodilator agents
Anticipate significant bleeding (consider previous sternotomy effects & anticipate response)
Identify & localize ischemia
Arterial and/or saphenous veins harvested

37
Q

Pre-Bypass

A

Administer Heparin
*Drawn up BEFORE sternotomy → available in case need to crash onto bypass
Check ACT

38
Q

Heparin MOA

A

Binds to antithrombin III & potentiates natural anticoagulant properties

39
Q

Heparin Dosage

A

300-400 units/kg

40
Q

Heparin Administration

A

Via central line BEFORE cannulas placed

*Check ACT 3-5min after administration

41
Q

Normal ACT

A

< 130 seconds

80-120 seconds

42
Q

ACT range required to start cardio-pulmonary bypass?

A

> 400-450

43
Q

Response to Heparin

A

↓SVR/BP 10-20%

44
Q

HIT

A

Heparin-induced thrombocytopenia
Antiplatelet antibodies → lead to platelet aggregation & potentially life-threatening thromboembolic events
Platelet count < 100,000
*Previous Heparin exposure
Check antibodies to antiplatelet factor IV

45
Q

Heparin Alternative

A

Bivalirudin

Direct thrombin inhibitor

46
Q

Pre-Bypass (Post Heparinization)

A

↓BP before aortic cannulation to prevent aortic dissection
TEE to assess Ca2+ deposits or plaques present in aorta
Aorta cannulation (arterial) 1st
- Perfusionist able to administer fluids through
R atrium (venous) cannulation 2nd
- HoTN and/or arrhythmias w/ venous placement
Coronary artery sinus cannulation - retrograde cardioplegia ↓BP

47
Q

Pre-Bypass Complications

A

Arrhythmias - cardiac manipulation & cannulation; potentially 1st sign myocardial ischemia
HTN especially during aortic cannulation
HoTN - admin volume via aortic line or pump; consider pressors
Heart failure
Bleeding - sternotomy lacerates R ventricle or aorta

48
Q

Transitioning to Cardio-Pulmonary Bypass

A

Perfusionist opens venous clamp to passively drain blood into the venous reservoir
Begins active patient cooling
A-line flat
Pull back pulmonary artery catheter 2-3cm into R ventricle
Assess for swelling or blanching (indicates improper venous catheter placement Ø adequate drainage from the head)
Pupils & BIS

49
Q

When to stop the ventilator?

A

When transitioning to bypass once the heart volume emptied

Bypass at full flows discontinue IV fluids

50
Q

Bypass Numbers

A

Pump flow 2.5-3L/min or 50-60mL/kg
Goal MAP 65-70mmHg (valve repair 50-60)
CVP 0-5 or (-) w/ vacuum assist to remove the blood
Mixed venous saturation 70-80%
Cerebral oximetry ↓normal when transition to bypass

51
Q

Pump Prime

A

Ask perfusionist
1,500-2,500mL balanced electrolyte solution
Crystalloid
Albumin, Heparin, bicarbonate, & Mannitol (↑osmolality ↓edema → promote diuresis)
Corticosteroids, antifibrinolytics, & blood products

52
Q

Anticipated patient response to going on bypass

A

Dilutional effect ↓viscosity (cooling ↑viscosity) ↓SVR → promotes blood flow to tissues
Catecholamine dilution → administer + inotropes
Hemodilution ↓O2 carrying capacity

53
Q

Cardio-Pulmonary Bypass Goal

A

Bloodless field
Still heart (not beating)
Quiet <3

54
Q

Hct %

A

20% acceptable
Goal 25-28%
Optimal viscosity = 30%

Admin PRBCs after patient off bypass

55
Q

How often to check labs after bypass initiated?

A

Q30min

ABG & ACT

56
Q

Cardioplegia Solution

A 
4°C
Reduces cardiac metabolism
Contains KCl 26mEq/L → depolarization
Glucose 43.9g/L
Mannitol 12.5g/L
NaHCO3 2.67mEq/L
Methylprednisolone Na+ 1g/L
Normosol-R
pH 7.6
Osmolality 480mOsm/Kg H2O
57
Q

When does V-fib occur?

Hint: Temperature °C

A

25-30°C

58
Q

When does the heart arrest?

A

DIASTOLE phase

59
Q

Cardio-Pulmonary Bypass Complications

A

HoTN ↓SVR
Renal ischemia d/t hypo-perfusion and/or hemodilution
CVA d/t thrombus in bypass pump (clot or foreign object)
Air emboli
Thrombocytopenia → extrinsic & intrinsic coagulation pathways activated
↑inflammatory response
Altered postop mental status “pump head”

60
Q

What patients are at an ↑risk to experience postop renal compromise?

A

Pre-existing renal conditions
Pump run time > 1hr
Elderly

61
Q

Cerebral Protection Mechanisms:

A

Hypothermia
Blood gas management
Adequate BP
BIS & cerebral oximetry

*Emboli 1° culprit → CNS complications

62
Q

When does re-warming the patient begin?

A

During the last anastomosis
Turn on warming blanket
Indicates close to coming off bypass
30-40min to re-warm patient

63
Q

Re-Warming

A

Begins PRIOR to aortic cross-clamp removal
When last distal anastomosis in angioplasty procedure
All valve sutures are in & knots are being tied down

64
Q

↑temperature ___°C per ___-___ minutes

A

↑1°C per 3-5 minutes

65
Q

What to anticipate w/ re-warming?

A

Recall risk - administer amnestic & neuromuscular blocker

Vasodilation ↓BP

66
Q

Preparation to come OFF bypass:

A 
Core temperature > 35°C (target 37°C)
Check labs: ABG, ACT, electrolytes, CBC+
1. Correct K+
2. Acid base balance
3. Hct%
Inflate the lungs w/ manual ventilation
Perform de-airing maneuvers
Remove aortic cross-clamp
Ensure HR > 90bpm (pacing as required)
Perfusionist slowly clamps the venous line & turns down flows to allow R atrium to fill
- Monitor PA & A-line pressures (anticipate ↑)
Pump off & venous cannula clamped = OFF bypass
Monitor CO via TEE, PA (re-float Swan Ganz), A-line
↑SvO2 indicates ↑O2 demand or ↓delivery 
Shivering → administer muscle relaxant
Turn ventilator on
Perform recruitment maneuvers PRN
67
Q

Hyperkalemia Treatment

A

CaCl 500mg

68
Q

Magnesium

A

2-4 grams

↓A fib risk

69
Q

How to restart the heart?

A

Surgeon administers “hot shot” warm cardioplegia solution w/o K+ after removing the cross-clamp

Unsuccessful?
Attempt internal shock or pacing

70
Q

Blood Glucose Goals

A

< 200
180-200

↑risk sternal wound infections w/ uncontrolled blood glucose levels

71
Q

Diabetic response to bypass:

A

↑glucose on bypass

Regular insulin gtt

72
Q

When providing recruitment breaths & manual ventilation what does the anesthetist need to monitor for?

A

Pressures < 30cmH2O

Internal mammary/thoracic artery anastomosis → LAD

73
Q

Aortic Cross-Clamp Time

A

Prolonged cross-clamp time α postop morbidity

74
Q

Normal patient response to aortic cross-clamp removal:

A

Paradoxical myocardial damage & limit recovery extent d/t free radicals released from the site (anaerobic metabolism)
Slow release
As blood flow returns, metabolites will be washed out

75
Q

Aortic Cross-Clamp

Complications

A

Hemorrhage at the cannulation site
Atheromas (clots) dislodgement
Aortic dissection

76
Q

What does ST elevation indicate?

A 
Myocardial supply & demand mismatch → ischemia
Air trapped in the heart
- Notify the surgeon
- De-airing maneuvers
- Needle insertion by surgeon
77
Q

Open Chest Defibrillation

A

10-30 joules

78
Q

Assessments when coming OFF bypass:

A

Contractility - heart filling & rhythm
TEE - volume, wall motion, valve function
Inspect for bleeding
Systemic α pulmonary artery pressure

79
Q

Protamine Dosage

A

1mg per 100 units Heparin

80
Q

Protamine Administration

A

SLOWLY via peripheral line

Potential to cause pulmonary HTN & R heart failure

81
Q

Post-Bypass Complications

A 
Recall
Neurocognitive changes
Bleeding - ↓clotting factors, fibrinolysis, thrombocytopenia, surgical blood loss, transfusion reaction, vessel trauma, & anaerobic metabolites
Organ hypo-perfusion
Emboli or thrombi
Systemic inflammatory response
Residual hypothermia
82
Q

Protamine

A

Multiple low-molecular weight proteins derived from salmon sperm
Neutralizes & reverses Heparin effects → Heparin-Protamine complex

83
Q

Protamine Half-Life

A

30-60 minutes

Potential to experience “Heparin rebound”

84
Q

When to check ACT after Protamine administration?

A

15-30 minutes

85
Q

Protamine Type I

Allergic Reaction

A

Histamine release → HoTN
Prevent w/ slow administration over 20-30min
Treat w/ volume or inotrope

86
Q

Protamine Type II

Allergic Reaction

A

IgE antibody mediated

Bronchoconstriction presents as anaphylactic reaction

87
Q

Protamine Type III

Allergic Reaction

A

Heparin-Protamine complex lodges in the pulmonary circulation
→ pulmonary HTN & R ventricle failure
Prevent w/ administering slowly via peripheral vein

88
Q

Closing the Chest

A

Cardiac tamponade type scenario where the heart squished & patient unable to tolerate → open back up
↓BP
Monitor TEE & hemodynamics

89
Q

Transport to ICU

A 
Ambu-bag
O2 tank
Monitors
Emergency drugs
Keep surgical table sterile
Transport assistance
Re-check breath sounds
Attach to ventilator 100% FiO2

AS - N934 Advanced Principles II (18 decks)

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