Brainscape's Knowledge GenomeTM

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


See full index

Advanced Principles of Anesthesia > Week 7 - Cardiac Anesthesia > Flashcards

Week 7 - Cardiac Anesthesia Flashcards

1
Q

What is included in the preop evaluation for a cardiac patient?

A

Assessment of cardiac characteristics:

  • cardiac history (acute unstable angina, acute MI, CHF, shock)
  • coronary lesion (left main high grade lesion, triple-vessel disease, diffuse lesion)
  • ventricular function
  • valvular disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are some common comorbidities in cardiac patients?

A
  • Carotid and cerebrovascular disease
  • Diabetes
  • Renal disease
  • Pulmonary disease
  • Peripheral vascular disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the most important factors in balancing myocardial oxygen supply and demand?

A

Heart Rate and Left Ventricular Pressure

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

What medications should cardiac patients continue taking preoperatively?

A

Beta Blockers
Calcium Channel Blockers
ASA
Long-acting insulin

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

What medications should cardiac patients hold preoperatively?

A

Diuretics
Renin-Angiotension-Aldosterone System inhibitors (ACE/ARB)
Warfarin
Short-acting insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When should cardiac patients stop taking their ACE/ARBs prior to surgery?

A

24 hours prior to surgery

*except Captopril can be held 12 hours prior

ACE/ARBs may cause vasoplegic syndrome – unexpected refractory hypotension under GA with MAP less than 50 mmHg, cardiac index > 2.5 L/min, and a low systemic vascular resistance despite vasopressor admin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What surgical risk assessment scales are used preoperatively for cardiac patients?

A

The Society of Thoracic Surgeons Cardiac Surgery Risk Score – allows calculation of pt’s risk of mortality and morbidities for the most commonly performed cardiac surgeries

European System for Cardiac Operative Risk Evaluation II – predicts risk of in-hospital mortality after major cardiac surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the most sensitive clinical monitor for detecting wall motion abnormalities cause by myocardial ischemia?

A

TEE

*completed before CPB to identify baseline pathology and function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the pros and cons of the different induction agents for cardiac surgery?

A
  • Etomidate causes less myocardial depression than propofol, but the adrenal suppression cause by etomidate is subject for debate
  • Etomidate provides more stable hemodynamic parameters compared to propofol in pts with poor LV function
  • Pts with severe LV dysfunction may require a primary narcotic technique since all volatile agents cause some degree of myocardial depression and afterload reduction

*typical to do large dose of versed and fentanyl for induction – slower but hemodynamically stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the hemodynamic goals pre-bypass in cardiac surgery?

A

Maintain perfusion pressure

Lower cardiac oxygen consumption

Increase oxygen supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the hemodynamic goals post-bypass for cardiac surgery?

A

Mean 60-70 mmHg

HR 80-90 bpm

Cardiac Index >2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are common medication infusions used in cardiac surgery?

A 
Phenylephrine
Norepinephrine
Epinephrine
Nitroglycerin
Nitroprusside
Nicardipine
Dopamine
Dobutamine
Tranexamic Acid
Insulin
Dexmedetomidine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What occurs from incision to bypass in cardiac surgery? What is the anesthetic goals?

A

Goal: Maintain Hemodynamic Stability

  • Incision and Sternotomy: narcotics, esmolol, deepen volatile, additional muscle relaxant
  • Harvesting of Grafts (if CABG)
  • Heparin 300-400 units/kg (ACT >450)
  • Cannulation: aortic cannula, venous cannula, antegrade/retrograde cardioplegia cannula
  • before aortic cannulation BP is decreased to SBP 90-100 or MAP <70 to decrease the risk of aortic dissection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the typical dose of heparin administered prior to initiation of cardiopulmonary bypass?

A

300-400 units/kg

  • ACT is measured 3-5 min after admin
  • Goal ACT is >400 seconds (450 at some places) – normal ACT = 80-120
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the advantages and disadvantages of using volatile anesthetics in cardiac surgery?

A
  • Potentially cause myocardial depression, vasodilation, and hypotension
  • Lower the arrhythmogenic threshold to catecholamines, and don’t provide pain relief in post-op period
  • Including volatile agents is associated with better outcome after cardiac surgery than using total IV technique
  • Most pts will benefit from myocardial protection of volatile agents (exception is severe LV dysfunction who can’t tolerate further cardiac depression)
  • Des and N2O raise PVR, PA pressure, and wedge pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why should nitrous oxide be avoided in cardiac surgery?

A

Potential for expansion of air introduced into the circulation during bypass

May cause catecholamine release and LV dysfunction

17
Q

What anesthetic technique facilitates early extubation post cardiac surgery?

A

Low to moderate dose narcotics (fentanyl 5-20 mcg/kg or sufentanil 2-10 mcg/kg) combined with volatile agent, or TIVA with short to moderate acting drugs such as remifentanil, propofol, or dexmedetomidine

18
Q

What are the advantages and disadvantages of narcotic use in cardiac surgery?

A
  • Don’t cause myocardial depression
  • Maintain stable hemodynamics
  • Can cause significant bradycardia, recall, chest wall rigidity, and prolonged intubation

*primary narcotic technique is reserved for hemodynamically unstable pts

19
Q

What is included in the pre-bypass checklist?

A
  • Anticoagulation (heparin admin, desired anticoag level - ACT >450)
  • Arterial cannulation
  • Venous cannulation
  • Pulmonary artery catheter (if used) pulled back
  • Are all monitors/access catheters functional?
  • TEE
  • Supplemental medications (muscle relaxant, anesthetics, analgesics, amnestics)
  • Inspection of head and neck (color, symmetry, venous drainage, pupils)
20
Q

What are the steps of cardiac surgery on CPB?

A
  • On bypass
  • Cross clamp aorta
  • Cardioplegia
  • Cardiac arrest
  • Grafts anastomosis
  • Unclamp aorta
  • Rewarming
  • Wean off CBP
  • Protamine
21
Q

Where is cardioplegia infused during cardiac surgery?

A

Solution infused either through:

  • a catheter placed in the aortic root (cardioplegia moves forward into the coronary arteries – antegrade)
  • a catheter placed in the coronary sinus (cardioplegia moves backward into the coronary veins – retrograde)
22
Q

What is the function of cardioplegia?

A
  • Keeps heart muscle still to allow surgery to be more easily completed
  • Greatly reduces the metabolic needs and oxygen requirements of the heart muscle, reducing the amount of ischemia during surgery

*may be infused multiple times during surgery to ensure the heart doesn’t beat

23
Q

What does intraop management of CPB look like?

A
  • With full flow there will no longer a pulsatile trace on the PA or A-line as blood is now bypassing the lungs
  • Stop mechanical ventilation
  • Vaporizer if used in attached to the oxygenator inlet of the CPB machine
  • Infusion of all IV fluids and most meds stopped (insulin and antifibrinolytics be continued)
  • CPB flow is temporarily decreased and aorta is cross clamped (note time)
  • Cardiac arrest ensues and cardioplegia is infused (high potassium) and then asystole
  • Active cooling may ensue, or allow patients temp to “drift” to ambient.
24
Q

What is the MAP goal while on CPB?

A

60 - 80 mmHg

*closer to 80 if pt has preexisting renal insufficiency or known atherosclerosis of carotid or cerebral arteries

25
Q

How is hypertension and hypotension typically treated while on CBP?

A

HTN: increasing anesthetic

HoTN: small boluses of phenylephrine (per perfusionist)

26
Q

What are the physiologic effects of CPB?

A
  • Systemic Inflammatory Response (SIRS)
  • Myocardial Injury
  • Neurological Deficits: Type 1 CVA, encephalopathy, coma, TIA – Type 2 confusion, agitation, disorientation, memory deficits, seizures (may improve after 3 months)
  • Pulmonary Complications (Atelectasis, Acute Lung Injury (ALI), ARDS, hemothorax, pnueomothorax, pulmonary edema)
  • Renal Dysfunction (ARF)
  • GI system dysfunction
  • Coagulopathies
27
Q

What is included in the discontinuation from bypass checklist?

A
  • Air clearance maneuvers complete
  • Rewarming completed
  • Address issue of adequacy of anesthesia and muscle relaxation
  • Obtain stable cardiac rate/rhythm
  • Pump flow and systemic arterial pressure
  • Metabolic parameters (normal limits, K+ 4-5.5)
  • Ensuring all monitors/access catheters are functional
  • Respiratory management (lungs re-expanded)
  • IV fluids restarted
  • Inotropes/vasopressors/vasodilators prepared
28
Q

What are the steps of coming off bypass?

A
  • As cardiac chambers are surgically closed, the lungs are inflated to remove air from the heart and pulmonary veins and to assist in filling the heart
  • Perfusionist lowers pump flow as surgeon removes aortic cross clamp
  • Heart will commonly fibrillate as it is re-perfused, internal defibrillation as indicated
  • Antidysrhythmics are often administered (lidocaine 100mg, Mg 1-2mg)
  • Optimal HR 80-90, AV asynchronous pacing if needed – change to synchronous mode when cautery use stops
  • Delivery of volatile or IV anesthetics
  • TEE assessment
  • Perfusionist then gradually occludes venous return to facilitate filling of RV, as arterial pressure rises CPB flow is gradually decreased and stopped
29
Q

What is the blood pressure goal during decannulation after CBP?

A

SBP 90 or MAP of 70 mmHg

*to decrease bleeding

30
Q

What is the dosing of Protamine after decannulation of CBP?

A

1mg Protamine to reverse every 100 units of heparin given

  • normal heparin dose of 30,000 units would require 300mg protamine
  • ACT is taken 3-5 min after protamine to confirm ACT returns to baseline
  • Give slow (mild hypotension) – anaphylaxis
31
Q

What occurs with cardiac tamponade?

A

Accumulation of blood in pericardium –> decreased SV –> compensatory rise in right atrial pressure –> septal shift to left –> diminished LV filling –> HoTN, systemic acidosis, myocardial ischemia, reduced CO

32
Q

What is Beck’s Triad?

A

Clinical Presentation of Cardiac Tamponade:

  • Hypotension
  • Jugular Distension
  • Distant muffled heart sounds
33
Q

What are the symptoms of cardiac tamponade?

A

Beck’s Triad (HoTN, jugular distention, and distant muffled heart sounds)

Pulsus Paradoxus: >10 mmHg decrease in SPV that occurs during inspiration

34
Q

How is cardiac tamponade diagnosed?

A

Chest X-Ray

Echo

*typically occurs 12-24 hours post cardiac surgery

35
Q

What regional anesthesia techniques can be used in cardiac surgery?

A
  • Central Neuraxial Block: thoracic epidural, spinal anesthesia
  • Peripheral Neuaxial Block: thoracic paravertebral block, intercostal nerve block
  • Field Block
36
Q

What are the benefits of regional anesthesia in cardiac surgery?

A 
Decreased opioid consumption
Pain control
Decreased surgical stimulus 
Fast track
Decreased respiratory complication
Hemodynamic stability
Decreased dysrhythmias
37
Q

What are the risks of regional anesthesia in cardiac surgery?

A 
Hematoma
Infection
Local anesthetic toxicity
Hypotension
Bradycardia
38
Q

What are the differences for Off-Pump cardiac surgery?

A
  • Good communication with surgeon
  • Require more volume replacement
  • Maintain normothermia, less neurological protection
  • Anticoagulation is necessary, but goal is usually at 300 ACT
  • Antifibrinolytics are not routinely used
  • MAP is kept relatively high during distal anastomosis (90-100)
  • Map is lowered with aortic anastomosis (60-70)
39
Q

Compare and contrast on-pump vs off-pump cardiac surgery

A
  • Surgical time: off-pump shorter
  • Transfusion rate: off-pump lower
  • Hospital & ICU stay : off-pump shorter
  • Neurological damage: off-pump lower
  • Overall perioperative complications: off-pump = on-pump
  • Graft-patency rate lower for off pump at three months: off-pump 88% vs. on-pump 97%
  • Similar early and late graft patency, incidence of recurrent or residual myocardial ischemia, need for reintervention, and long-term survival

Advanced Principles of Anesthesia (31 decks)

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