Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AP III Oral Exam > Cardiac/Bypass > Flashcards

Cardiac/Bypass Flashcards

1
Q

Preop eval of cardiac patient

A
  • Cardiac:
    • Severity of disease/hemodynamic status
    • Degree of impairment of contractility
    • Development of compensatory mechanisms
    • Exercise tolerance
    • Hx of CHF, or MI-ST segment changes
    • Angina
    • Dysrhythmias
    • Compensatory increase in sympathetic nervous outflow, ie ­Hr, anxiety, diaphoresis
    • Hx of previous surgery
  • Pulmonary
    • COPD
  • Renal
  • PVD-especially carotid disease
  • Diabetes
  • Obesity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Laboratory data for cardiac patients?

A
  • CBC
  • Electrolytes
  • Cardiac Enzymes
  • Serum Creatinine
  • Coagulation profile
  • Type and Cross

Must have PRBCs available

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Lab data for MI?

A

Peak A, early release of myoglobin or CK-MB isoforms after AMI

Peak B, cardiac troponin after AMI

Peak C, CK-MB after AMI

Peak D, cardiac troponin after unstable angina.

  • The most recently described and preferred biomarker for myocardial damage is cardiac troponin. (gold standard)
  • Absolute myocardial tissue specificity
  • High sensitivity
  • Thereby reflecting even microscopic zones of myocardial necrosis.
    • ​will see peak even after only angina

Apex-

  • CKMB
    • initial elevation 3-12 hours
    • peak 24 hours
    • return to baseline 2-3 days
  • Troponin I
    • Initial 3-12 hours
    • Peak 24 hours
    • return 5-10 days
  • Troponin T
    • initial 3-12 hours
    • peak 12-48 hours
    • returnto baseline 5-14 days
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Other cardiac testing you may want to evaluate before cardiac surgery?

A
  • Catheterization data
    • LVEDP
    • EF
    • CI
  • Echocardiography data
    • EF
    • Wall motion abnormalities
  • Chest X-Ray
    • Cardiomegaly
    • Pulmonary vascular congestion, edema, effusion
  • Angiography
  • EKG
    • Ischemia/infarct
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Monitors used for cardiac surgery?

A
  • Pulse Ox
  • TEE
  • EKG
    • Leads V5(ischemia) & II (arrhythmia)
  • Temperature
  • ABP
    • Usually radial, sometimes femoral
  • CVP
    • Mandatory for infusion of drugs
  • PA Catheter
    • Pts with severe LV dysfunction
    • Pts with profound pulmonary HTN
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

TEE use in cardiac?

A
  • Intermittent pulses with a frequency of 2.5-7.5 MHz.
  • Can determine:
    • Preload
    • Hypotension
    • CO
    • LV Filling Pressures
    • LV contractility
    • LV afterload
    • Ischemia, emboli, valvular pathology
    • Assessment of surgical repairs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Cardiac OR setup?

A
  • Usual airway equipment/machine check
  • Pacemaker
  • Drips
    • Vary b/w institutions
    • Most commonly:
      • NTG/NTP
      • Epinephrine/Norepinephrine
      • Phenylephrine/Ephedrine
      • Dopamine/Dobutamine as needed
      • Antiarrhythmics (esmolol, lidocaine, mag, amiodarone)
  • Heparin-and coag. monitoring capability
  • Emergency drugs
  • PRBC available in OR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Goals of induction and intubation of cardiac patient?

A
  • Smooth induction
    • Avoid cough, larygospasm, truncal rigidity
    • Avoid hypo- or hyper- tension
  • Deep plane of anesthesia
  • Short duration laryngoscopy
  • Tape tube, eyes
  • Pad pressure points
  • Check monitors in this busy period
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Considerations for incision to bypass period

A
  • Intense surgical stimuli → STERNOTOMY
    • Hypertension
      • Deepen the anesthetic
      • Narcotics (PAINFUL)
      • Vasoactive agents
        • NTG/NTP
    • Sternotomy
      • Drop lungs
        • Disconnect circuit from ETT/vent (lungs will deflate)
  • Heart Handling by surgeon
    • Communication is of the utmost importance
      • Arrythmias/HoTN common
    • Bleeding can be significant
    • Identifying and localizing ischemia
    • Arterial and Saphenous veins are harvested
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Considerations around the administration of heparin prior to initiation of bypass?

MOA of heparin? Dose? Peak?

A

Anti-coagulate the pt with Heparin

  • MOA:
    • Binds to antithrombin 3 (AT3) and potentiates its natural anticoagulant properties on Factor Xa and thrombin
  • Dose: 200-300units/kg (300-400 unin/kg from bypass lecture)​
    • Admin via central line or by surgeon directly into R atrium
    • Dose is facility dependent
      • Ex: 70 kg pt → 28,000 units (or round up to 30,000 units)
      • Once the chest and pericardium are open and surgeon is happy with exposure, they will ask the anesthesia provider to give heparin via IV or will give it directly into the right atrium
  • Peak: 2 mins
    • 3 min → Check activated clotting time (ACT)
      • Normal ACT = < 130 seconds (70-110 average)
      • Heparinized ACT = 350-500 seconds acceptable (> 400-450)
        • *Safe to go on bypass
    • Administered through CVP or directly into RA

Considerations:

  • SVR & BP can ↓ by 10-20%
    • D/t blood viscosity reduction
      • While blousing → monitor for HoTN and tx
  • ACT checked after 3-5mins
    • (Should be > 300-400 sec)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are some special cirucmstance that would interfere with heparinization?

A

Special circumstances that interfere with heparinization- Examples: ACT may not increase

  • Antithrombin III deficiency
  • Long term heparin therapy
  • Excessive hemodilution
    • min fluids → interferes w/ heparinization
  • Heparin-induced thrombocytopenia
    • Antibody mediated response
  • NTG long term
    • Heparin resistance?
  • Alternatives to increase ACT:
    • FFP
      • ​Inconvenient (must thaw and want to avoid blood product during CV sx)
      • 1 unit of ATIII per mL of FFP
      • ~ Adult: usually 2 units of FFP
    • Thrombate III
      • Scenario: Appropriate heparin dose admin and ACT doesn’t increase appropriately → admin thombate III or FFP, then wait, then give additional dose of heparin and check ACT
      • NEVER go on pump unless appropriate ACT

From bypass lecture:

Look for ATIII level from preop labs

  • Sometimes ACT will not reach the goal of 480 seconds with the loading heparin dose alone, when this happens the first step is for the perfusionist to provide the anesthesia provider with a second, smaller dose of heparin in hopes of getting closer to goal ACT
  • Increasing heparin dose w/ increasing body wt is only effective to some degree bc the heparin is mainly distributed in plasma.
  • Once the additional heparin reaches > 600 units/kg and the pt is still < 300 seconds → pt is “heparin resistant”
  • Heparin does need anti-thrombin 3 as a co-factor to work
    • so even additional heparin will not provide enough anti-coagulation because of an anti-thrombin 3 deficiency.
  • This can be inherited or acquired r/t prior heparin exposure.
    • Why it’s helpful to get pre-op ATIII level so a poor response to heparin can be anticipated and prepared for.
  • In cases when you have ATIII deficiency → Administer:
    • recombinant anti-thrombin (thrombate) or
    • FFP (contains ATIII)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What cannulations are performed to initiate CPB

A

Bypass:

  • Aorta (Arterial side) → brings O2 rich blood to systemic circulation
  • RA (venous side) → brings O2 blood back from systemic circulation

Cannulation

  • 1st→ Aortic cannulation (Arterial side): must DROP BP!! (esp if calcified)
    • Can cause aortic rupture!
    • Ex: SBP 90-100
      • Cannulated 1st bc perfusionist can rapidly admin fluids through arterial line in case BP drops
    • Arterial cannula size
      • Too small → limit flow due to increased resistance and then jetting of blood (high pressure) – this can potentially cause an aortic dissection, biggest risk of cannulation
      • Too large → cause vessel damage
        • Need balance
        • Adult Cannula Size: 22 - 24 French aortic canula
    • Once the arterial canula is in place, the perfusionist will check the arterial line pressure is reading as this is a reflection of the [aortic] root pressure
      • excessively high = sign of aortic dissection.
      • Perfusionist will check for pulsatility so some fluctuation up and down in the pressure on the A-line, and can give a test transfusion of a small amount of volume to ensure the pressure doesn’t jump up.
    • The surgeon wants the pressure on the LOWER side for canulation to avoid additional bleeding during this period.
      • The pt will lose blood during cannulation, but this is only temporary.
    • Hypotension should be treated with VASOPRESSORS not volume.
  • 2nd → RA cannula (venous side):
    • BP might drop &/or arrhythmias can occur while placing
  • 3rd → Cannulation of the coronary sinus for retrograde cardioplegia to arrest heart
    • Anatomy: Coronary sinus is where coronary vessels empty into to get reperfused
    • Retrograde cardioplegia- providing poor RV myocardial perfusion, stopping the heart
      • Cannulation → similar effects as RA (severe ↓ BP)
        • Tx: Fluids by perfusionists, vasoactive agents
  • *Medicate pt w/ extra Midaz and Fentanyl right before going on bypass
    • Priming fluid of bypass machine increases Vd → diluting anesthetic agents
      • INCREASE RECALL RISK
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What needs to occur (by anesthesia) when initiating bypass?

A
  • Pt placed on bypass, adequate perfusion flow and pressure, pt cooling starts (arterial side)
    1. Cease ventilation (dc circuit)
    2. IV fluids shut off
    3. Volatile anesthetic turned off
    4. Make sure perfusionist has instituted anesthetic
    5. Pull back Swan catheter – tends to float in further
    6. Give NMB to prevent shivering, along with fentanyl/versed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens with the intiation of bypas?

A

Significant drop in BP

  • Causes:
    • Hemodilution → ↓ viscosity
      • From priming fluids (perfusionist)
    • Rapid dilution of catecholamines
    • Rapid cooling
      • for brain, heart, liver
    • Aortic cross-clamp-to prevent systemic extravasation of antegrade cardioplegic solution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are some hematological effects of CPB?

A
  • Effects both extrinsic and intrinsic coagulation pathways
    • Factor XII conversion to Factor XIIa on various surfaces of CPB circuit
  • Directly impairs platelet function
    • Rapid adhesion and conformational alteration of plasma proteins
      • i.e., von Willebrand factor (vWF) and fibrinogen (Fib)
    • Platelet aggregation, and detachment due to shear forces
  • Monocyte and endothelial activation with TF and tissue/vessel injury
  • Tissue (vessel) injury → Extrinsic pathway → release of TF → causes both initiation of intrinsic pathway and common pathway
    • Intrinsic pathway (via IX)
    • Common pathway (via X)
  • Understand adhesion and damage to cell from pt being on bypass
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are some CNS risks while on pump? People at risk?

A

Risks:

  • Embolization
  • Hypoperfusion
    • Bypass machine at low pressures/flow
  • Inflammation from pulsatile to flow BP

Influencing Factors/predisposition: (people at risk)

  • Aortic atheromatous plaque (atherosclerosis in aorta)
  • Cerebrovascular disease
  • Altered cerebral autoregulation (elderly)
  • HoTN
  • Intracardiac debris
    • Plagues
  • Air
  • Cerebral venous obstruction on bypass
  • Cardiopulmonary bypass circuit surface and damaged blood cells
  • Reinfusion of unprocessed shed blood (cell saver)
  • Cerebral hyperthermia (rewarmed too quickly)
  • Hypoxia (serial ABGs)
17
Q

How can we provide cerebral protection while on bypass?

A
  • Emboli are biggest culprits
  • PROTECTION:
    • Hypothermia → decrease CMRO2
    • Barbiturate therapy?
      • Used to give TPL/Methohexital decrease BF to brain
    • CCBs
      • increase perfusion to brain
    • Blood gas management
      • Draw from aline
    • Adequate BP (run machine at good flows)
      • blood cell damage vs. CPP? Individualized
        • (look at risk list above and those prob need higher pressures)
    • Cerebral oximetry
18
Q

Rewarming considerations?

A
  • Begins at different times: (Surgeon can ask for rewarming of pt)
      1. Begins prior to aortic cross-clamp removal (or)
    • 2. Begins with the last distal anastomosis in angioplasty procedure (or)
    • 3. Begins when all the valve sutures are in and knots are being tied down
  • Considerations:
    • 1° C per 3-5 mins (slowly)
      • Usually takes ~ 30-40 mins
    • Turn on heating blanket
    • Temp gradient bt arterial and venous blood should remain < 5-10°C
      • if gradient higher → higher risk of air emboli
    • Amnestic and NMB agents should be given (recall)
    • SVR drops d/t vasodilation
      • Monitor pressure*
      • Phenylephrine can be given to perfusionist since they have more direct access
19
Q

What must occur prior to the discontinuation of bypass?

A
  • Pt must be warmed
  • Surgical field should be _dry (_no bleeding)
  • Lab values checked
    • Admin Ca & Mag to decrease effects of cardioplegic soln (high K)
  • Pulmonary compliance evaluated
    • Begin ventilating lungs slowly (attach circuit)
      • Manually bag pt to see compliance → watch lungs
      • Then switch to ventilator
  • Regulate cardiac rhythm by pacing, defibrillating or pharmacologically
    • Ca, Mg
  • Transfuse pt with pump volume (~50-100cc by perfusionist)
    • Look at:
      • PA Diastolic pressure
      • TEE*
      • Actual heart over drapes (floppy?)
      • VS
20
Q

Pneumonic to help remember preparation to wean from bypass?

A
  • ( see pic)“CVP”
  • C
    • Cold
    • Conduction
    • CO
    • Cells- PRBCs
    • Calcium
    • Coagulation
  • V
    • Ventilation
      • Visualization
      • Vaporizers- turn on gas since perfusionist turns off theirs
      • Volume expanders- for HoTN
  • P
    • Predictors:
      * Based off preop assessment
      * Arrythmias beforehand?
      • Pressure
      • Pressors
      • Pacer
      • Potassium/Mag/Calcium balance
      • Protamine- AFTER everything else looks good (last thing)
21
Q

Considerations during discontinuation of bypass?

A
  • Use the ratio of systemic BP to pulm BP
  • EXAMPLES:
    • If pulm pressure ↑, but BP ↓ = ventricular failure (inotropic agent)
      • PA pressure high → diastolic fx not working properly and BP low → SV or stroke pressure poor → ventricle not fx properly
        • Tx: Inotropic agent→ increase force of contraction
    • If CO is low, but BP is adequate = SVR high (overly vasoconstricted)
      • BP good but heart cant pump against heavy constriction
        • Tx: vasodilation
    • If BP is low:
      • Inotropes
      • volume (cell saver, PRBC, whole blood)
  • Diagnose THEN treat
    • Look at BP and PA pressures
  • Once the pt is stable, bypass is completely d/c’d
22
Q

How do we support ventricular function during bypass weaning?

A

Assess function

LV support =

  • Inotropes
  • PRBC
  • Preload
  • afterload

RV support = (need to ↓ pulm vasoconstriction)

  • Nitric oxide-based vasodilators
  • β2 agonists
  • prostaglandin E1
    • RV failing unrelated to pulm vasoconstriction:
      • cyclic adenosine monophosphate-specific phosphodiesterase inhibitors
        • (Phosphodiesterase inhibitors are a class of medications that promote blood vessel dilation (vasodilation) and smooth muscle relaxation in certain parts of the body, such as the heart, lungs, and genitals)
    • If not working:
      • IABP (intra-arterial balloon pump)
      • Ventricular Assist Devices
23
Q

What is protamine? Dosage?

A
  • Derived from salmon sperm
    • Pts w/ vasectomies (develop AB against sperm) → Allergic Rx to protamine
  • Dose:
    • 2-4 mg/kg
    • 1-1.3 mg per 100units of Heparin given
      • Administration considerations:
        • SLOWLY push (over 5-10 min)
          • *Massive vasodilation/drop in BP*
        • CVP line (draw back and ensure good line)
        • Check ACT and give more accordingly
          • ~ < 100
24
Q

Considerations for anaphylaxis with protamine?

A
  • Anaphylaxis can occur: Admin w/ premedication or alternatives to heparin
    • Pts with previous exposure
    • Pts with vasectomy
    • Pts on NPH (Neutral Protamine Hagedorn) (prior exposure technically)
      • Can cause vasodilation, give slowly over >5mins.
  • Pts with documented adverse events related to protamine → do not rechallenge with protamine
  • Pharmacologic alternatives to protamine:
    • Do not reverse heparin
    • Non–heparin-based CPB
    • Performing off-pump coronary artery bypass (OPCAB) with an alternative to heparin
      • Surgeon dependent (variable)
  • Non-protamine heparin reversal drugs: (if heparin used)
    • PF4
    • Heparinase
      • MOA: deactivates heparin (not technically reversing it)
    • Simply waiting for heparin’s effects to dissipate
25
Q

What are the types of protamine reaction?

A
  • Something that we always have to be aware of happening, there are several different types of protamine reactions
  • Type I: systemic hypotension
    • r/t histamine release caused by protamine
      • tx:
        • give protamine slowly
        • give IV fluids
  • Type II: true anaphylaxis
    • IgE mediated
    • most commonly seen with prior protamine exposure or NPH use.
    • Tx: steroids, epinephrine, anti-histamines and PPV
  • Type III: catastrophic pulmonary vasoconstriction/flash pulmonary edema
    • → right heart failure → left heart failure & hypotension
    • Tx:
      • Tx myocardial depression
      • → re-heparinize and go back on CPB
    • There are no protamine alternative, so the only option is to wait and allow heparin to be metabolized
26
Q

What are some common causes of bleeding post bypass?

Interventions?

A
  • surgical (proline suture deficiency)
  • hypothermia
  • coagulation dysfunction
  • re-do operations → BLEEDING (cordis/rapid infuser available)
  • Interventions:
    • Obtain post protamine ACT
      • Consider heparin rebound → seen in Obese pts
        • Most heparin bound in plasma but some migrates to tissues
      • ½ life Protamine 30-45 min → may need redose
    • Cell saver blood (only high Hct)
      • No clotting factors → consider FFP
    • TEG
      • Elongated R time: residual heparin → reverse w/ protamine
    • If a pt’s coagulopathy and bleeding cannot be controlled with blood products, you may need to give factor 7 (FEIBA) – which is Factor 8 inhibitor bypass agent, this is an off label use for serious bleeding after bypass. Comes with risk of thromboembolic complications
27
Q

Review of TEG?

various times/treatments?

A
  • R time 5-10 minutes
    • definition- time to clot formation
      • problem with coag factors
    • treatment- FFP
  • K time 1-3 minutes
    • definition- time until clot reaches fixed strength
      • problem with fibinogen
    • treatment cryo
  • Alpha angle 53-72 degrees
    • definition- speed of fibinr accumulation
      • problem with fibrinogen
    • treatment cryo
  • MA 50-70 mm
    • def- highest vertical amplitude of teg
      • problem with platelets
    • treatment- PLT and/or DDAVP
  • LY30 0-8%
    • def- percentage of amplitude reduction 30 min after MA
      • problem with fibrinolysis
    • treatment
      • TXA/amicar
28
Q

What are some strategies to conserve blood during CPB?

A
  1. Retrograde autologous prime (RAP)
  2. Venous Autologous prime (VAP)
  3. Minimal prime volume and IV fluids
  4. hemoconcentration
  5. minimize cooling
  6. diuresis
  7. antifibrinolytics
  8. ANH
  9. Autotransfusion/cell salvage
29
Q

What is retrograde autologous prime?

A
  1. Replace crystalloid circuit prime volume w/ pt’s own blood
    1. Process may cause HoTN → tx w/ pressors or have perfusionist stop
      1. DO NOT tx w/ fluid
  2. Perfusionist will reduce the crystalloid prime of the circuit by replacing it with the pt’s own blood volume.
  3. Once the cannulas are placed and attached to the circuit, we slowly allow blood from arterial cannula to flow retrograde and we replace the crystalloid volume in the arterial line with blood.
  4. We may even be able to replace the crystalloid prime of the oxygenator with blood if the pt’s BP can tolerate it.
  5. crystalloid volume that is replaced will be removed from the circuit
  6. This process will likely cause hypotension, we don’t want anesthesia to treat this with fluid because that would defeat the purpose of RAP-ing but you can treat with vasopressors or have the perfusionist stop the process
30
Q

What is acute normovolemic hemodilution (ANH)?

A
  1. For normal or high Hgb
  2. Remove whole blood in OR prior to sx repair
    1. from central/a line → into bag w/ anticoag CPDA
      1. ~400-500 ml and place on rocker
  3. Replace volume w/ crystalloid/albumin
    1. volume that is taken off is replaced by anesthesia with either crystalloid or albumin, idea is that the blood loss during surgery will now be more dilute
    2. Also this higher Hct blood that is collected prior to CPB won’t be exposed to the circuit and can be given back to pt once protamine is given
  4. Expires after 8 hrs
31
Q

What is autotransfuion/cell salvage?

A
  1. Collect shed blood from surgical field
    1. Mixed w/ heparin
  2. Centrifuge to [] RBC
    1. Removal of plasma volume (highly concentrate RBC)
  3. Wash w/ 0.9% NaCl 1000 ml
  4. End product: ~60% Hct
    1. 50-70% Hct
    2. Higher pH
    3. Lower K+ than banked blood (bank blood a/w poorer CV sx outcomes)
  5. Devoid of CF
    1. Washed out CF, heparin, WBC

AP III Oral Exam (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions