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CV Anesthesia > Test 1 > Flashcards

Test 1 Flashcards

1
Q

List the three most effective monitors used to detect myocardial ischemia

A
  • ECG
  • PAC
  • TEE
  • Visual
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2
Q

List major branches of the right coronary artery

A

o SA Nodal
o AV nodal Acute Marginal
o Posterior descending artery

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3
Q

List major branches of the left coronary artery

A
  1. Left anterior descending -> diagonal, septal perforator, intermediate
  2. Circumflex -> obtuse marginal, posterior descending artery
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4
Q

List two factors which both decrease myocardial oxygen supply and increase demand

A

o Heart rate and PCWP

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5
Q

Discuss the role of heart rate management in optimizing myocardial oxygen supply and demand

A

o Along with CPP, most important cause of myocardial ischemia
o LV fills during diastole
o Total time in diastole key in perfusion
o Modest increase in demand major effect on supply
–> Total time in diastole decreases and heart rate increases

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6
Q

Identify the hemodynamic variable most commonly associated with myocardial ischemia

A

o When heart rate increased to 146 bpm; SBP increased to 196 mmHg
 Angina increases 80% in hr and 30% with SBP
 ST depression increase 70% with hr and 20% with SBP
 In Anesthesia if hr <70- less than 30% have ischemia, if hr > or = 110- about 65% may experience ischemia

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7
Q

List four factors which may adversely affect ventricular wall tension

A 
(CPP = DBP -LVEDP) 
o	Systolic BP
o	Afterload
o	LV filling volumes
o	Myocardial ischemia
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8
Q

Identify the effect of intra-Aortic balloon pump on myocardial oxygen supply

A

o During diastole, the balloon inflates and augments the diastolic pressures via coronary and systemic perfusion

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9
Q

Identify the effect of the intra-aortic balloon pump on myocardial oxygen demand

A

o During systole, the balloon deflates and it reduces afterload
 DECREASE cardiac workload
 Decrease myocardial oxygen consumption
 Increase cardiac output
 Decrease hemodynamic abnormalities associated with mechanical defects

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10
Q

Identify the most commonly associated complication associated with CABG

A
  1. Afib or other rhythm disturbances: 22%
  2. MI: 5-10%
  3. Post op bleeding: 5%
  4. Death: 3-4%
  5. Acute renal failure: 2-5%
  6. Sternal wound infection: 2-5%
  7. Stroke: 1-2%
  8. Post-perfusion syndrome: “pumphead”
  9. Respiratory failure: “pump lung”
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11
Q

List four predictors of morbidity/mortality with CABG

A 
o	Age
o	Previous MI
o	Location of MI
o	Coagulopathy 
o	CHF/Heart failure
o	Dysrhythmias
o	HTN
o	DM
o	Cerebrovascular disease
o	PVD
o	Valvular heart disease
o	Cigarette smoking
o	Lung disease 
o	ECG abnormalities
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12
Q

Identify which time period is most associated with morbidity/mortality after an MI

A

o <1 mo: 35%
o <6 mo: 15%
o >6 mo: 5%

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13
Q

List two tests measuring ventricular function in the patient presenting for CABG

A

o Cath, echo

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14
Q

List three commonly used home medications in patients with CAD presenting for CABG

A

o Beta blockers -> bradycardia, withdrawal HTN/tachy, last dose
o Calcium blockers/Ace Inhibitors -> hypotension, orthostasis
o Diuretics/Thiazides-> hypovolemia, orthostasis, hypokalemia
o Hospital meds -> Heparin, nitrates, insulin

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15
Q

List three indications for placement of a pulmonary artery catheter

A

o LV dysfunction
o Angina within the last 48 hours
o Symptomatic valvular disease
o Severe hypertensive with angina history
o Large operation with anticipation of intravascular volume changes
o Vascular surgery with clamp of major artery

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16
Q

Describe four uses of pulmonary artery catheter data during CABG

A

o Measure CO and optimize perfusion
o Detect, treat and trend myocardial ischemia
o Measure and optimize ventricular preload and volume in surgery with large volume shifts
o Measure and optimize ventricular preload and volume in surgery during aortic cross clamp
o Detect, treat and trend valve dysfunction

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17
Q

Describe three clinical uses of intraoperative TEE during CABG

A 
o	Ventricular function (EF, wall motion)
o	Wall motion abnormalities 
o	Valve dysfunction 
o	Stenosis or regurgitation 
o	Chamber size may be indicative of dysrhythmias, dysfunction
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18
Q

Calculate drug doses for induction using commonly used anesthetic agents
(Phenylephrine)

A

30-60 mcg/min vs. bolus

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19
Q

Calculate drug doses for induction using commonly used anesthetic agents (Midazolam)

A

3-5 mg

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20
Q

Calculate drug doses for induction using commonly used anesthetic agents (Propofol)

A

20-100 mg

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21
Q

 Calculate drug doses for induction using commonly used anesthetic agents (Etomidate )

A

 10-20 mg

22
Q

 Calculate drug doses for induction using commonly used anesthetic agents (Fentanyl )

A

3-25 mcg/kg

23
Q

 Calculate drug doses for induction using commonly used anesthetic agents (Sufentanil )

A

0.5-1.5 mcg/kg

24
Q
  1. Muscle Relaxants ( Three)
A

 Vecuronium, Rocuronium, Succinylcholine

25
Q

Describe the effect of fentanyl on volatile agent requirements

A

o Fentanyl25mcg/kg: 40% reduction on MAC
o 50 mcg/kg: 55% reduction on MAC
o 75 mcg/kg: 65% reduction on MAC
o 100 mcg/kg: 75% reduction on MAC
o Fentanyl increases HR, MAP CI, and MVO2 upon sternotomy
o Halothane and Nitrous control HR but decrease MAP, CI, and MVO2 during sternotomy

26
Q

Identify the dose of epinephrine associated with extrasystoles when using isoflurane

A

o 10 mcg/kg of epinephrine = 100% of patients exhibit ventricular extrasystole
o 7 mcg/kg = 50% of patients exhibiting ventricular extrasystole
o At 5 mcg/kg = less than 20% exhibit ventricular extra systole

27
Q

List three causes of myocardial ischemia During Anesthesia

A 
o	Coronary artery occlusion
o	Tachycardia (>100/min)
o	High PCWP/CVP (>12-15) 
o	Hypotension 
o	Severe hypertension
o	Increased workload of heart or high cardiac output (sepsis
28
Q

List three signs of myocardial ischemia

A 
o	St segment abnormality 
o	Dysrhythmias 
o	Conduction abnormality 
o	PA waveform abnormality 
o	Decreased myocardial performance (low CI or BP)
o	Wall motion abnormality (echo, visual)
29
Q

Identify four subgroups of patients requiring higher perfusion pressures (higher MAP)

A 
o	Acute MI/Ongoing Ischemia
o	Renal/Cerebral Insufficiency
o	Left Main/Left Main Equivalent 
o	Aortic Stenosis 
o	Chronic Hypertension
30
Q

List four potential sources of conduit for bypass grafts for CABG

A
  1. Mammary Harvest
     LIMA: almost always harvested as a graft unless subclavian stenosis or emergency
     RIMa: rarely harvested due to distance to heart from right sternum but may be used as “free graft”
     IMA: may need to hand ventilate during harvest -> prone to spasm, surgeon will check flow after harvest and attach bulldog +/- papaverine for spasms
    **Heparin may be given in varying mounts if mammary opened and flow checked
  2. Vein Graft Harvest
     SVG 30” to 5=10 years
     Can be endoscopic vs. open harvest
     Heparin 3000 units administered prior to taking vein from leg
     Greater saphenous usually taken but if previous CABG or bad vein may go prone for lesser saphenous
  3. Radial vein harvest
  4. Gastric-epiploic harvest
31
Q

Discuss blood pressure maintenance during aortic cannulation

A

o Aortic cannulation sutures with tourniquet will be placed in ascending aorta (MAINTAIN SBP <100 mmHg, communication with surgeon)

32
Q

List four sources of rhythm disturbances associated with surgical manipulation immediately prior to cardiopulmonary bypass

A

o Atrial cannulation/vent stitch (death grip, etc.)
o RFG catheter (retrograde cardioplegia)
o Pericardiotomy
o Lap under heart to explorer distal
o Myocardial ischemia
o Dissecting out heart for red/pericarditis

33
Q

Discuss heparin dose and target ACTs for on-bypass CABG

A

o Heparin 300 units/kg at some point

o ACT > 400 seconds at some point after pericardiotomy and prior to aortic cannulation

34
Q

Describe the hemodynamic consequences of “mixing” or “RAPing”

A

o “Mix/Rap”
 Retrograde autologous priming
 Drains venous blood from patient to prime CPB circuit
 Decreases viscosity and circulating norepinephrine levels (decreases SVR)
o Mugging/Leeching by surgeon dealt with by transfusion back from CPB, alpha drug, and communication

35
Q

List four goals or priorities of cardiopulmonary bypass

A

o Oxygenation of blood and elimination of carbon dioxide (ventilation
o Circulation of the blood
o Systemic cooling and rewarding
o Diversion of blood from the heart to provide a bloodless surgical field (aortic crossclamp, cardioplegia

36
Q

Compare cross-clamp strategies for distal anastomoses and proximal anastomoses

A

o Distals usually done with cross clamp on
o Mammary usually done last (to avoid twisting IMA)
o Reward initiated after last distal
o Cross-clamp removed, partial clamp of aorta for proximals
o Heart defibrillated 10” after clamp off if in VF/VT
o At risk for ischemia until proximals competed

37
Q

Discuss protamine dosing after separation from CPB

A

o Remove venous cannulation and drain venous circuit of heart-lung machine into reservoir (extra volume)
o When satisfied with heart performance start protamine after 10 mg test dose
o Give 25 mg Protamine every minute
o Typical protamine dose is 250 mg
o Administer volume from pump to compensate for arterial and venous dilation
o Remove aortic cannula when ½ of the protamine dose is in

38
Q

Compare OPCAB to conventional CABG in regards to construction of distal anastomoses

A
  1. OPCAB
     Beating heart, absence of CPB
     Use of an epicardial stabilizer and displaced heart
     Temporary interruption of coronary blood flow during anastomoses and regional ischemia
     Bypass of 1-7 vessels
     Extubation either on table or very shortly thereafter

 Timing of hemodynamic manipulation is optimized by knowing order of grafts, when displacement is to occur
 After displacement, silastic tape is placed around vessel to produce proximal coronary occlusion and lift vessel into better place
 If tolerate, the epicardial stabilizing device is placed

 Stabilization of the target site is accomplished by using one of the many stabilizer, which work by compression and lifting
 These stabilizers create an immobile field, but if used as retractors the heart will slip and compression will cause hemodynamic compromise

39
Q

List four potential advantages of OPCAB over conventional CABG

A

o Less neuropsychological impairment (short-term only, ? Same at 12 months)
o Transient periods of regional myocaridal ischemia instead of global myocardial ischemia
o Fewer inotropes, fewer dysrhythmias postop
o Improved hemostasis
o Less need fro transfusion and fluids
o Less postoperative renal insufficiency

40
Q

List from subgroups of patients that may benefit from OPCAB

A 
o	Age > 70 years
o	Low EF
o	Reoperative surgery 
o	Patients with significant comorbidities: cerebrovascular disease, peripheral vascular disease, bleeding disorders, COPD, renal dysfunction 
o	Atheromatous or calcified aorta
o	Patients who refuse blood products
41
Q

Describe the role of intracoronary shunts in performing distal anastomoses

A

o A double limb shunt (proximal and distal ends) is placed after arteriotomy
o Bleeding from arteriotomy site during anastomoses is reduced
o Coronary blood flow is maintained through reduced
o Blood loss results regardless

42
Q

Describe methods used to displace the heart for distal anastomoses

A

o Octopus stabilization system lifts and immobilizes the anastomotic site
o Suction cup or starfish is use that lifts the apex by applying suction
o Saline/carbon dioxide irrigation system is used to maintain clear surgical

43
Q

Describe the effect of cardiac displacement on CI, left/right ventricular filling, myocardial oxygen supply and demand and heart rhythm

A

o Thin right atrium is compressed by positioning, resulting in decreased RV filling but elevated filling pressures
o Decreased RV output results in an under-filled left ventricle and low stroke volume/cardiac output
o Decreased CO results in decreased BP

o	Marked decrease in cardiac output and SV
o	Profound hypotension 
o	Increased filling pressures 
o	Valve dysfunction
o	MI
o	Dysrythmias
44
Q

Identify the target vessel positioning most associated with decrease in SV and increase in CVP

A

o The vertical position of the heart produces distortion of the mitral and tricuspid annuli and significant regurgitation may occur
o Large “v” waves on the pulmonary artery tracing without LV failure are diagnostic
o Abnormal valves become more distorted by positioning

45
Q

List four strageties used to manage heart rhythm disturbances during OPCAB

A

o Rhythm disturbances from ischemia or mechanical issues
o Consider lidocaine infusion, especially for RCA
o Mag 2 grams, maintain K at 4.0
o NTG often administered during distal anastomoses for spasm
o Pacemaker always ready available due to need for higher HR

46
Q

Discuss heparinization and target ACTs for OPCAB

A

o Heparin dose should be 1.5-2 mg/kg, aiming to keep the ACT > 250 seconds during vessels anastomoses
o Dose usually 10,000-15,000 units (1/2 full CPB dose)
o Heparin 3000 units if vein taken prior to bolus for revascularization
o ACT should be repeated every 30 min

47
Q

Compare PAC use to TEE for monitoring of cardiac performance and ischemia during cardiac displacement

A

o ECG position dependent
o PCWP affected by displacement and ischemic
o Arterial line, operative field are best monitors
o CI superior to TEE with displacement
o TEE is useful for RWMA

48
Q

List four surgical maneuvers which may limit hemodynamic compromise during cardiac displacement

A

o Order of grafts based on hemodynamic consequences (LAD-PDA-Circ)
o OR graft most diseased vessel first
o Close communication with anesthesia with modification of position as needed
o DPS to bring great vessels and chambers into same plane

o Open right pleura for lateral walls grafts to allow heart to rotate and avoid compression
o Open right pericardium to allow heart to drop into right chest cavity
o Lift right sternum to make more space for the heart (towel under right side of sternal retractor)
o Remove pleurocardial fat pad to make more room for heart

o Suture musculofascial tissue on the posterior part of mediastinum to allow heart to drop posteriorly
o Moderate right lateral decubitis positioning at 30-45 degrees to allow gravity-assisted rotation of the heart rightward and preserve hemodynamics

49
Q

Describe management of heart rate, vascular tone and LV filling immediately prior to cardiac displacement

A

o Maintenance of reasonable heart rate
o Background infusion of norepinephrine (2-6 mcg/min) may be utilized to maintain BP and CO
o Infusion should be utilized instead of bolus, port closest to circulation
o Volume loading (500 ml Albumin vs 2000 ml crystalloids) immediately prior to verticalization and stabilization

o If CI remains less than 1.5, bolus doses of epi (10-20 mcg) are administered
o Proactive treatment of ischemia-induced ventricular function is essential
o Right ventricular compression especially with verticalization requires increase preload to maintain left ventricular filling
o Anticipation of distals and effect on BP/CI essential, hespan/trendelenberg key

50
Q

Describes uses and limitations of NTG during OPCAB

A

o Useful in optimizing coronary perfusion pressure by decreasing PCWP
o Decreases wall tension and MVO2
o Decrease mitral regurgitation and pulmonary artery pressures
o Double edge sword as decrease in preload can be detrimental, as higher filling pressures are needed to ensure optimal ventricular filling

51
Q

Compare protamine reversal of heparin with OPCAB

A

o Reversal dose is 1 mg protamine for every 1/3 mg active heparin (usually 100 mg protamine, dose variable sometimes only 50 mg)

CV Anesthesia (1 decks)

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