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Anesthesiology > Cardiac/Thoracic Anesthesia > Flashcards

Cardiac/Thoracic Anesthesia Flashcards

0
Q

What effect does hypothermia have on platelets?

A

Decreased temperature causes reversible sequestration in portal circulation

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1
Q

Who needs prophylaxis against infective endocarditis?

A

Only needed in high risk patients undergoing high risk procedures

High risk patients:

  • prosthetic heart valves
  • history of infective endocarditis
  • unrepaired congenital heart disease (or recently repaired)
  • valvulopathy in transplanted heart

High risk procedures:

  • Dental work
  • Respiratory procedures
  • Skin/musculoskeletal procedures
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2
Q

What is the most sensitive indicator of left ventricular myocardial ischemia?

A

Wall motion abnormalities on echo

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3
Q

What is normal O2 consumption at rest?

A

3.5 mL/kg/min

This is equal to 1 MET

For an average 70 kg person, this is about 250 mL/min

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4
Q

What does the y-axis of the Frank Starling curve represent? What values can be used?

A

Left ventricular work

Can be represented by:
LV stroke work index
Stroke volume
Cardiac output
Cardiac index
Arterial blood pressure
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5
Q

What does the x-axis of the Frank Starling curve represent? What values can be used?

A

Left ventricular filling pressure

Can be represented by:
LVEDV
LVEDP
Left atrial pressure
PA wedge pressure
CVP
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6
Q

What can cause a rise in PA pressure during cardiopulmonary bypass?

A

Distal migration of the PA catheter (very common - should resolve if catheter is withdrawn 3-5 cm)

Inadequate ventricular venting / ventricular distention

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7
Q

How does body temperature affect tissue metabolic rate?

A

For each degree Celsius below 38, tissue metabolic rate decreases approximately 5%

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8
Q

How might malposition of the aortic cannula during cardiopulmonary bypass present? What about the venous cannula?

A

Aortic cannula - unilateral facial blanching

Venous cannula - facial or scleral edema

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9
Q

Pts with bicuspid aortic valves are predisposed to what other cardiac abnormality?

A

Aortic dissection

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10
Q

How does an intra-aortic balloon pump work? What are common indications? What are the contraindications?

A

Deflates just before systole, reducing aortic pressure and afterload, which enhances LV ejection and reduces wall tension and O2 consumption

Inflates during diastole, just after closure of the aortic valve, which increases diastolic aortic pressure and coronary blood flow

Common indications include cardiogenic shock, failure to wean from CBP, severe MR, or as a bridge to transplantation

Contraindications include AI, aortic disease, and severe peripheral vascular disease

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11
Q

What special mechanism makes epinephrine so useful in the treatment of Vfib?

A

Epinephrine reduces the ventricular fibrillation threshold and cellular refractory period, thereby stabilizing fibrillation

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12
Q

What type of drugs are Milrinone and Inamrinone? How do they work? What is the difference?

A

PDE III inhibitors

  • decreases in both SVR and PVR via vasodilation
  • increases CO (inotropy) via increase intracellular calcium

Inamrinone is associated with thrombocytopenia and has largely been replaced by Milrinone

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14
Q

What are the hemodynamic goals for aortic stenosis?

A

1) Decrease heart rate (increase filing)
2) Maintain sinus rhythm
3) Maintain/increase preload

4) Maintain/increase afterload
- in order to maintain coronary perfusion

5) Maintain PVR

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15
Q

What are the hemodynamic goals for aortic regurgitation?

A

1) Maintain preload
2) Increase HR (less time for the blood to regurgitate)
3) Maintain contractility
4) Decrease/maintain afterload

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16
Q

What are the hemodynamic goals for mitral stenosis?

A

1) Maintain/increase preload
2) Decrease HR (to increase injection time)
3) Maintain contractility
4) Maintain afterload
5) Decrease/maintain PVR

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17
Q

What are the hemodynamic goals for mitral regurgitation?

A

“fast, full, forward” by avoiding bradycardia, ensuring adequate preload, and avoiding high afterload

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18
Q

What are the hemodynamic goals of tricuspid stenosis?

A

1) Maintain/increase preload
2) Decrease/maintain HR
3) Maintain/increase afterload
4) Maintain PVR
5) Maintain contractility

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19
Q

What are the hemodynamic goals of tricuspid regurgitation?

A

1) Maintain/increase preload
2) Maintain/increase HR
3) Maintain afterload
4) Decrease PVR
5) Maintain contractility

20
Q

What are the hemodynamic goals of pulmonic stenosis?

A

1) Increase preload
2) Increase HR
3) Maintain preload
4) Decrease PVR
5) Maintain contractility

20
Q

What is the difference between concentric and eccentric hypertrophy?

A

Concentric hypertrophy is increased wall thickness with no change in chamber size and is pressure related

Eccentric hypertrophy is increase wall thickness with increased chamber size and is volume related

21
Q

What happens if Protamine is given to a patient who has not received Heparin?

A

It can cause anticoagulant effects by binding to platelets and soluble coagulation factors

22
Q

What is normal daily production of cortisol? What about during times of stress?

A

Normal daily production is 15 to 20 mg. Under stress, production can increase to 75 to 150 mg/day.

23
Q

What is the Fick equation for cardiac output?

A

Oxygen consumption / [(arterial O2 content - mixed venous O2 content) x 10]

24
Q

What is normal myocardial O2 consumption?

A

8 to 10 mL/100 g/min

25
Q

What is resting coronary artery blood flow?

A

75 mL/100 g/min

About 5% of cardiac output

26
Q

How much Protamine is required to reverse Heparin?

A

1.3 mg of Protamine for each mg of Heparin given

27
Q

What happens when a magnet is placed over a combined ICD/pacemaker?

A

The cardioversion and defibrillator functions are disabled

Pacemaker settings are unchanged
- EP must reprogram the pacemaker of changes are desired

28
Q

Which patients should be started on pre-operative beta blockade?

A

Any patients with 3 or more risk factors for CAD (ischemic heart disease, congestive heart failure, stroke, diabetes, chronic kidney disease) who are undergoing high risk surgery

Patients already on beta blockers should continue them peri-operatively

29
Q

What nerve can be injured during surgical repair of a patent ductus arteriosus?

A

The recurrent laryngeal nerve (branch of CN X)

30
Q

What are the hemodynamic goals in HOCM/IHSS

A

Preload should be kept up

Afterload should be kept up

Heart rate should be kept down

Contractility should be kept down

Sinus rhythm should be maintained

31
Q

Describe the effects of aging on the CV system

A

Resting systolic function (EF) is unchanged, but exercise-induced increases in CO, SV, and HR are reduced

Plasma levels of circulating catecholamines are significantly elevated
- Due to decreased sensitivity of Beta receptors

Increased vascular fibrosis and diastolic dysfunction, leading to increased reliance on the atrial kick

Fibrosis of conduction system can lead to arrhythmia

32
Q

What are alpha-stat and pH-stat? What is the difference?

A

Alpha-stat and pH-stat are pH management strategies during cardiopulmonary bypass

Alpha-stat is temperature uncorrected and maintains normocarbia and normal pH by assuming pt is at 37 degree celcius

pH-stat is temperature corrected and maintains normocarbia and normal pH based on the pt’s actual temperature
- Infuses extra CO2 into the blood to compensate for decreased temperature

33
Q

What are the hemodynamic effects of aortic cross-clamping?

A

Increased arterial blood pressure above the level of the clamp
- decreased blood pressure below the clamp

Increased coronary artery blood flow

Increased left ventricular wall stress

Increased central venous pressure and pulmonary artery wedge pressure

Decreased cardiac output

Decreased oxygen extraction

34
Q

Describe the thermodilution method of determining CO. What causes under-/over-estimation?

A

A set volume of injectate at a set temperature is administered through the CVP port of the PA catheter and travels distally towards the thermistor at the tip

The thermistor detects how much and how quickly the temperature changes after injection

  • a smaller change is interpreted as a larger CO (less time for injectate to mix)
  • a larger change is interpreted as a smaller CO (more time for injectate to mix)

Any error that increases the temperature change (larger volume or colder temperature) will lead to an under-estimation of CO

Any error that decreases the temperature change (smaller volume or warmer temperature) will lead to an over-estimation of CO

35
Q

How should you manage the pacemaker when a pacemaker-dependent patient comes to the OR?

A

Ideally, you should re-program the pacemaker to an asynchronous mode at a rate higher than the patient’s intrinsic rate

You can place a magnet over a pacemaker, but it is unreliable and manufacturer dependent

36
Q

During one-lung ventilation, what are some strategies to improve oxygenation?

A

Bronchodilators and suctioning

CPAP to the non-ventilated lung

PEEP to the ventilated lung

Occluding the PA of the non-ventilated lung

37
Q

What are the risk factors for heparin resistance? What is the treatment?

A

Risk Factors:

  • Preoperative heparin therapy
  • Use of LMWH
  • Age over 65

Treatment is with FFP, AT3 concentrate, or recombinant AT3

38
Q

What are the important values of a TEG and what do they tell you?

A 
Reaction time (R) is from time zero to initial clot formation
- prolonged R values result from coagulation factor abnormalities, factor deficiencies, or heparin
Coagulation time (K) measures speed of clot formation and strengthening
- prolonged K values result from inadequate fibrinogen
Maximum amplitude (MA) measure the strength of the fully formed clot
- decreased MA suggest platelet dysfunction

Alpha angle is the speed of clot formation
- decreased alpha angle results from inadequate fibrinogen

39
Q

Describe the response to bronchodilators seen in COPD patients

A

Response to bronchodilators follows a bell-shaped curve

  • mild or severe COPD patients usually show MINIMAL response
  • moderate COPD patients usually show GREATEST response
41
Q

How are PFTs used for risk stratification in thoracic surgery?

A

High risk factors include:

  • FEV1 less than 40% predicted
  • DLCO less than 40% predicted
  • VO2 max less than 10 mL/kg/min

If PFTs are unfavorable, you can perform split-lung function testing

42
Q

In what situations is a bronchial blocker preferred over a DLT? What would a DLT be better?

A

It is better to use a blocker for:

  • selective lobar collapse
  • challenging airways
  • patients with trachs
  • children less than 12
  • when post-op mechanical ventilation is expected

DLTs are more reliable than blockers when you want true lung isolation

43
Q

How does hypothermia effect pH?

A

For each degree Celsius temperature decrease, the pH of blood increases by approximately 0.017

44
Q

How do TEE, EKG, and PCWP compare in terms of sensitivity for detecting myocardial ischemia?

A

From most sensitive to lease:

  • TEE
  • EKG
  • PCWP
45
Q

How can you estimate transvalvular pressure gradients based off of echo findings?

A

Bernoulli equation

transvalvular pressure = 4 * (peak velocity)^2

46
Q

What are the risk factors associated with post-CBP acute kidney injury?

A

Creatinine over 1.2
Combined valve and bypass procedures
Pre-op intra-aortic balloon pump
Emergency procedures

Anesthesiology (12 decks)

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