Cardiovascular Anesthesia Pt. II (Exam III) Flashcards
When is the highest risk of mortality from a surgery after an MI?
Within the 1st 30 days after the MI
When should an arterial line be placed for cardiac surgery?
Preoperatively (preop area or pre-induction)
What drug is necessary prior to cardiac surgery in the preop area?
Versed
How should an initial reading with the cerebral oximeter be measured?
Baseline measurement at room air
What four factors result in our cerebral oximeter reading?
- MAP
- FiO₂
- Hgb
- EtCO₂
What is the most important thing during sternal incision?
Lungs need to be down
What possible complication can occur doing a redo sternotomy on someone who had previous heart surgery years ago?
Pericardium can be adhered to sternum and at risk of being cut by the saw.
What changes should be made from a first time steronotomy to a redo sternotomy?
2ⁿᵈ Sternotomy needs:
- Blood in room
- Bypass primed and on field
What should be done as the pericardium is opened?
- Assess color of pericardial fluid (should be straw-colored)
- ↓ lung volumes as pericardium is tacked.
Systolic BP must not exceed _______ mmHg as we cannulate.
90 - 100 mmHg
What is the bypass dose of heparin?
3mg/kg
or
300units/kg
What is the ideal body weight dosage of heparin for cardiopulmonary bypass?
Trick question. Heparin for bypass is dosed on actual body weight.
ACT must be greater than ______ to go on bypass.
400
When is ACT drawn after heparin administration?
3 - 5 minutes
What should an ACT be for off-pump heart surgeries?
300 - 350 is acceptable
If a repeated dose of heparin does not achieve an ACT of 400 or greater, what should be considered?
ATIII deficiency (consider giving FFP or ATIII directly)
How often must cardioplegia solution be administered to maintain cardiac arrest?
Every 20 - 30 min
CMRO₂ will decrease __% for every 1°C drop in temperature.
7%
What is the temperature goal in cardiac surgery?
32°C
Where are bypass grafts sewn first? Why is this?
Distally
Done so that warming can begin.
What is our target temperature during re-warming?
35.5 - 37°C
When should postoperative sedation start being considered during a cardiac operation?
During re-warming.
Versed, Precedex, Propofol…
What aortic clamp is used to allow partial flow whilst sewing on proximal grafts?
Partial occluder clamp
What cannot be maintained if a patient is cold coming off bypass?
Stable rhythm
Cold = V-fib.
What joule dosage is used on the internal defibrillator paddles?
20 - 30 joules
What is our BP goal around decannulation time?
90 - 100 sBP
When are antibiotics typically redosed in CV surgery?
Decannulation
Dependent on drug and bypass time.
What should be done prior to restarting the patient on the ventilator after cardiopulmonary bypass?
Alveolar recruitment
What is the dose of protamine for CPB reversal?
1mg/kg
How is protamine best administered?
IV Piggyback
What should be held as the chest is wired shut?
Respirations
What specific type of pump is most often used in adult CPB?
Roller pump
What are the most important characteristics of a centrifugal roller pump?
- Pressure limited
- Higher prime volume
What priming solution is most often used for a CPB pump?
Crystalloid typically
What is the typical priming volume for a CPB pump?
1500 - 2500 mLs
What additive may be included in a CPB circuit dependent on specific patient factors?
- Albumin
- PRBCs
- Electrolytes
- Mannitol
- Heparin
What hematocrit would be expected for a patient on CPB? Why?
Low HCT expected (17 - 25%)
This is due to dilutionary effects from the pump prime.
What two things are used for myocardial protection during cardiac surgery?
- Cold, Hyperkalemic Cardioplegia
- Systemic Hypothermia
Where is cardioplegia administered in:
Antegrade?
Retrograde?
- Antegrade = Aortic root
- Retrograde = Coronary sinus
- On occasion a graft may also be used
What is the most common lung injury due to CPB?
Pump Lung (Acute Lung Injury)
What are the characteristics of pump lung?
- Diffuse congestion & edema
- Hemorrhagic atelectasis
What is the main CNS complication of CPB?
“Pump Head”
- Stroke is also a major risk
What is the cause of Pump Head?
- Small emboli
- Hypotension
What is the major GI complication of CPB to watch out for?
Mesenteric Infarction
What are the possible causes of CPB induced mesenteric infarction?
- Emboli
- Hypoperfusion
- HIT
What is the urine output goal for cardiac surgery?
1 mL/kg/hr
What factors will increase the risk of acute renal injury post cardiac surgery?
- Pump time (non-pulsatile time)
- Excessive blood loss
- DM
- Vasopressor usage
- Advanced age
What anti-fibrinolytic has replaced aprotinin?
Cyclokapron
Cyclokapron may increase risk of bleeding if administered more than ____ hours prior to surgery.
3 hours
What drug will work as a hemostatic agent in cases of extreme fibrinolysis?
Cyclokapron
What is the dose of cyclokapron for cardiac surgery?
10mg/kg bolus
1-2 mg/kg/hr infusion
What is the generic name of cyclokapron?
Tranexamic Acid
Off pump CABG’s (OPCAB) are most successful with a normal _____.
EF
How are vessels grafted differently in OPCAB surgeries?
Grafts sewn proximally first and distally second.
How often are ACT’s checked during OPCAB?
every 20 min
What major anesthetic issues should be considered in cardiac transplantation?
- Denervated heart
- Immunosuppressant effects
- CAD
What is the major consequence of denervated heart in a cardiac transplant patient?
SNS > PSNS due to lack of vagal input
HR higher, atropine & glyco won’t work, etc.
What sensory capability is lost by a patient who has a heart transplant?
No sensory ability
CAD w/o angina!!!
Immunosuppressants must be discontinued during the perioperative period in transplant patients. T/F?
False. Immunosuppressants must be continued.
What should occur in regards to preload and vasodilation with cardiac transplant patients?
- Maintain preload
- Avoid vasodilation
What two echocardiogram views are commonly used in cardiac surgery?
- Transverse 4-chamber
- Transgastric short axis
What are contraindications to TEE?
- Esophageal stricture
- Esophageal mass
- Esophageal varices
- Zencker’s Diverticulum
- S/P radiation to the neck
- Recent gastric bypass surgery
What view is depicted below?
Aortic Valve Short Axis view
What view is depicted below?
4-chamber view
What view is depicted below?
Transgastric Short Axis
What view is depicted below?
Left Atrial Appendage view
What view is depicted below?
Ascending Aorta Short Axis
What are the characteristics of a bioprosthetic valve?
- Bovine or porcine
- 10 - 15 year duration
- Lower clotting potential
What are the characteristics of metal valves?
- Metal or carbon alloy
- Last 20 - 30 years
- Highly thrombogenic
What are risk factors for mitral stenosis?
- Female
- Rheumatic fever
- RA
- SLE
How quickly does mitral stenosis occur?
Slowly (20 - 30 years)
What is a normal mitral valve opening?
4 - 6 cm²
At what surface area does an obstruction of LV filling occur with mitral stenosis patients?
MV area ≈ 1.5 cm²
What type of murmur is heard in mitral stenosis?
Diastolic murmur at apex
What s/s of mitral stenosis are common?
- DOE
- Orthopnea
- PND
- A-fib
- Embolism
What EKG changes are seen in mitral stenosis patients?
- Broad notched p-waves
- LAE on EKG
- A-fib
What is the medical treatment of mitral stenosis?
- Maintain NSR
- Diuretics (↓ LAP)
- Anticoagulation
What are the surgical treatment option for mitral stenosis?
- Balloon Valvulotomy
- Commissurotomy
- Replacement
What are our anesthetic goals for mitral stenosis patients?
- Prevent/treat pulmonary edema
- Prevent/treat Afib
- Avoid ↑ CVP
- Avoid ↓ SVR
Stenosis generally requires ____________ of normal parameters.
Maintenance of normal parameters (normal BP, normal HR, etc)
What are common causes of mitral regurgitation?
- Endocarditis
- MV prolapse
- LV hypertrophy
- Papillary muscle dysfunction
- SLE
- RA
- Ankylosing spondylitis
- Carcinoid syndrome
A regurgitant fraction of ________ is considered severe mitral regurgitation.
greater than 0.6
What factors contribute to the degree of regurgitation of a mitral valve?
- MV orifice size
- HR
- Pressure gradients
What type of murmur is heard with mitral regurgitation?
Holosystolic apical murmur radiating to axilla
What EKG changes are seen with MR?
LAE & LVH on EKG
Overall left axis deviation.
What two hemodynamic changes should be avoided in mitral regurgitation?
- Bradycardia
- ↑ SVR
What hemodynamic parameters would indicate the need for mitral valve replacement for regurgitation?
- EF < 30%
- Right SV > 65mL
Is repair or replacement preferred for mitral regurgitation? Why?
Repair is preferred
What HR should be maintained in mitral regurgitation?
normal to slightly high
The phrase “Forward, Fast, & Full” describes the anesthetic goals for what valvular pathology?
Mitral Regurgitation
What induction agent might be best for MR?
Etomidate (minimal cardiac depression & SNS activity)
Why might VAA’s be good for severe MR?
VAA will ↓ SVR
Aortic stenosis will occur earlier in life if the valve is ______.
bicuspid
What is the normal valvular surface area of the aortic valve?
2.5 - 3.5 cm²
At what surface area is aortic stenosis considered severe?
< 0.8 cm²
What are the s/s of aortic stenosis?
- Angina
- Syncope
- DOE
- Left axis deviation
What murmur is heard with aortic stenosis?
Systolic murmur that radiates to the neck
The murmur heard from aortic stenosis may sound like what other pathologic condiditon?
Carotid bruit
What murmur is heard with aortic regurgitation?
Diastolic murmur at the right sternal border
What s/s are seen with aortic regurgitation?
- Widened pulse pressure
- LV dysfunction
- Fatigue/Dyspnea/Coronary ischemia
- Left axis deviation
Warfarin and direct thrombin inhibitors should be discontinued _____ days preop.
3 - 5 days
How long must warfarin be held prior to starting neuraxial anesthesia?
5 days
How long must lovenox be held prior to neuraxial anesthesia?
12 - 24 hours
How long must apixaban, rivaroxaban, etc be held prior to neuraxial anesthesia?
3 days
How long must Clopidogrel (Plavix) be held prior to starting neuraxial anesthesia?
5 - 7 days