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FRCA Final > Cardiothoracic anaesthesia > Flashcards

Cardiothoracic anaesthesia Flashcards

1
Q

What is the mortality for lobectomy and pneumonectomy?

A

2-4% and 6-8% respectively

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2
Q

What is ppoFEV1?

A

Predicted postoperative forced expiratory volume in 1 second. It is the most validated marker for post operative respiratory complications.

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3
Q

How can you calculate the ppoFEV1?

A

(Pre-op FEV1) X (% lung remaining) = ppoFEV1 (functionally inactive lung pre-operatively doesn’t contribute)

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4
Q

What is TLCO or DLCO?

A

This is the transfer co-efficient using carbon monoxide. A measure of diffusion capacity of the lung. When referenced to lung volume it is given as KCO.

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5
Q

What are the risk categories for ppoTLCO?

A

low risk: >40% moderate-high risk:

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6
Q

What are the boundaries of the paravertebral space?

A

Anteriorly: Parietal pleura Posteriorly: Costotransverse ligament Medially: spinal foramina

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7
Q

What are the risk categories for ppoFEV1?

A

Low risk: > 40% Moderate risk: 30-40% High risk:

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8
Q

Name structure 1.

A

Dorsal root ganglion (sensory)

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9
Q

Coronary Perfusion Pressure

A

CPP = Aortic Root Diastolic Pressure - LVEDP

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10
Q

Myocardial O2 Extraction Ratio

A

70%

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11
Q

Coronary sinus saturation

A

30%

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12
Q

Standard approach to cardiac anaesthetics

A
  • Consider Lorazepam 2-3mg 2 hours pre-op
  • Fentanyl 5 - 15 mcg/kg
    • NB, Fentanyl is filtered out in CPB
  • Propofol up to 1.5 mg/kg
  • Pancuronium / Vecuronium preferred
  • Isoflurane (mimics ischaemic pre-conditioning, lowers myocardial O2 demand, steal syn. probably not an issue)
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13
Q

Institution of CPB - Anticoagulation requirements

A

ACT > 480 seconds

Requires Heparin 300-400 units/kg

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14
Q

Establishing CPB

A
  1. Heparinise, aim SBP 100 mmHg
  2. Cannulate aorta
    • 100 mL bolus, test bounce
    • Check not carotid
  3. Site venous pipes (Bicaval/Right Atrium)
  4. Attach cardioplegia lines
  5. Increase flow from CPB
  6. Aortic cross clamp
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15
Q

What are the essential component of CPB

A
  • 1 or 2 Venous cannulae
  • Venous reservoir
  • Fresh gas supply (and volatile vapouriser)
  • Oxygenator
  • Heat exchanger
  • Pumps
  • Arterial cannulae (and filter)
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16
Q

Qualities of a bubble oxygenator

A
  • Positive
    • Efficient
    • Cheap
    • Low resistance
  • Negative
    • Difficult to control O2/CO2 independently
    • Causes haemolysis and clotting abnormalities
    • Limited to a few hours use
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17
Q

Qualities of a membrane oxygenator

A
  • High resistance
  • Less damaging to blood components
  • Provides long term support (12 hours or more)
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18
Q

What is a membrane oxygenator?

A

Cellulose or polypropylene membrane arranged in hollow fibres. Blood and gas phases are separated, gas exchange occurs by diffusion

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19
Q

Myocardial Preservation Techniques

A
  • Cardiostable GA
  • Pre-conditioning
  • CPB - offloading heart reduces myocardial work
  • Aim:
    • Hb 7-10
    • MAP > 70
    • CPP > 50
    • Slow heart rate
    • Turn off ionotropes once on CPB
    • Venting of LV
    • Avoid LV distention (AR very difficult)
  • Cardioplegia
  • Hypothermia
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20
Q

St. Thomas’ (No.2) Cardioplegia Solution

A
  • K - 16 mmol/L
  • Mg - 16 mmol/L
  • Ca 1.2 mmol/L
  • NaCl - 120 mmol/L
  • NaBicarb - 10 mmol/L
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21
Q

Blood cardioplegia

A
  • Good supply of protein buffers, nutrients and O2
  • Superior to crystalloid
  • Excellent if myocardium ischaemic
  • Cold intermittent administration
    • Warm administartion rarely used
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22
Q

Cardioplegia route of administration

A
  • Antegrade:
    • Via aortic root, direct into ostia
    • Problems if CA obstruction, AR, LVH
  • Retrograde:
    • Via coronary sinus
    • May not garuntee protection of RV
  • Often a combnination technique is ued
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23
Q

Protamine dose

A

1mg per 100 units of Heparin

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24
Q

Problems with protamine

A
  • Histamine release
  • Myocardial depression
  • Systemic vasodilatation
  • Severe anaphylactoid reactions
  • Acute catastrophic pulmonary hypertension and RV failure
  • GIVE SLOWLY (5-6 mins)
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25
Q

Proceedure for coming of CPB

A
  • Warm to 36.5
  • Establish cardiac rate and rhythm compatible with CO
  • Lungs ventillating
  • Iontropes back on if needed
  • IABP monitoring functional
  • Check metabolic disturbance
  • Perfusionist ready with adequate blood in reservoir
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26
Q

pH-STAT or alpha-STAT

A
  • alpha stat - typically in adults (reduces risk of neurological injury from microemoli)
  • pH stat - typically neonates (reduces risk of neurological injury from hypoperfusion)
27
Q

pH Stat regulation

A
  • Maintains pH in normal range when corrected for temperature, by the addition of CO2 into CPB
  • Creates a mild acidosis when measured at 37°C
  • Promotes vasodilitation with increased risk of microemboli.
28
Q

alpha stat regulation

A
  • Maintains pH in normal range when measured at 37°C
  • Alpha describes the unprotonated fraction of imidazole moiety of histidine (most important intracellular buffer)
  • Thought to be more physiological
  • Promotes acid load removal from metabolically active tissues
  • Preffered in adults
29
Q

CPB’s effect on blood and complement

A
  • Activates alternative pathway
  • C3a and C5a increase on CPB
  • Triggers polymorphonuclear leukocytes (PMN) to marginate and adhere
  • PMNs increase capillary leakage
  • Platelets activated (Increased adherance, reduced function)
  • Erythrocytes (increased haemolysis)
  • Cytokines (Increased TNF and IL-8)
  • Kallikrein-Kinin system activation (bradykinin release)
30
Q

CPB’s endocrine response

A
  • Increased:
    • Catecholamine release
    • ADH
    • Cortisol
    • Renin, Angiotensin, Aldosterone
  • Reduced:
    • Insulin response
31
Q

Organ Dysfunction following CPD

A
  • Brain: 1-2% Major CVA, Post Op cognitive impairement
    • Macro/Micro emboli
    • Hypoperfusion
    • Inflammatory response
  • Respiratory: Post pump pulmonary dysfunction
    • Emboli causing V/Q mismatch
    • Complement PMN activation
    • Increased pulmonary hydrostatic pressure (poor venting)
    • TRALI
  • Renal: dysfunction in 15%
    • Hypothermia
    • Hypoperfusion
    • Haemoglobinuria 2° to haemolysis can cause ATN
  • Liver: Hepatic dysfunction in 20%
    • Hypotention, hypoxia
    • Worse with high Right pressures
32
Q

MIDCAB

A

Minimally invasive direct coronary artery bypass. A left anterolateral thoracotomy for single LIMA to LAD graft

33
Q

OPCAB

A

Off Pump Coronary Artery Bipass. Also called Beating Heart Surgery

34
Q

Why is OPCAB beneficial

A

Avoids all the pitfalls of CPB

35
Q

Anaesthetic implications of OPCAB

A
  • Prepare for sudden loss of CO (prepare for CPB)
  • Expect high bleeding
  • Arrythmias are common (cardiac manipulation)
  • Potential for severe MR and TR (and severe pulmonary oedema)
  • Challenging to maintain normothermia (lots of the body exposed)
  • Myocardial ischaemia detection difficult as ECG unreliable
36
Q

Anaesthetic technique for OPCAB

A
  • Cardiostable GA
  • Consider thorassic epidural
  • Monitor for ischaemia
    • TOE
    • PAC (increased PA pressure with LV ischaemia)
  • Avoid ionotropes
  • Small doses phenylephrine to maintain coronary perfusion pressure
  • Minimise arrythmias from handling
    • 8 mmol Mg over 15 mins
    • K > 4.5
  • Beaware of pulmonary oedema - diuretics as needed
  • Consider cell salvage
  • Fluid warming, heated mattress
  • Aim ACT > 350
37
Q

Insidious signs of postoperative cardiac tamponade

A
  • CVS deterioration
  • Increasing ionitropic requirements
  • Rising CVP
  • Dropping urine output
  • Evolving metabolic acidosis
  • Poor end of the bed-o-gram
38
Q

Treatment of postoperative cardiac tamponade

A

Return to theatre for re-sternotomy under GA. note, needle pericardiocentesis is inappropriate in this setting as it will not remove clot

39
Q

Moving a patient back to theatre for re-sternotomy (intubated)

A
  • Maintain all monitoring
  • Hand ventillate and maintain appropraite sedation
  • Maintain all ionotropic infusions
  • X-Match 2 units minimum (plus other products)
  • Ensure NMB
  • Switch onto Isoflurane
  • Consider BIS
  • Take baseline ABG
  • Small dose fentanyl
  • Start
40
Q

Moving a patient back to theatre for re-sternotomy (non-intubated)

A
  • Maintain all monitoring
  • FiO2 = 1 via 15 L NRB mask
  • Maintain all ionotropic infusions
  • X-Match 2 units minimum (plus other products)
  • Patient is heavily dependent on sympathetic drive to maintain CO - GA will remove this
  • Prepare for surgery proir to induction
  • Etomidate 0.15-0.2 mg/kg
  • Rocuronium 1 mg/kg
  • Consider RSI
  • Expect loss of output
  • Start
41
Q

Causes of excessive bleeding post cardiac surgery

A
  • Surgical haemostatic problem
  • Inadequte reversal of heparin
  • Excessive fibrinolysis
  • Reduced platelet count/function
  • Clotting factor deficiency
  • Complement activation
42
Q

Anaesthetic considerations for heart transplanted patients

A
  • Note cardiac denervation
  • CO cannot increase by HR easily
  • CO can increase by SV (i.e fluid)
  • Chronically elevated catecholamine levels
  • Epedrine / Atropine ineffective
  • Adrenaline / Isoprenaline better
  • Maintrain pre-load at all costs
  • Note accellerated athersclereosis and silent ischaemia
43
Q
A
44
Q

Describe the different parameters in TEG

A
  1. R-time: reaction time (s); time of latency from start of test to initial fibrin formation (amplitude of 2mm); initiation
  2. K-time: kinetics (s); time taken to achieve a certain level of clot strength (amplitude of 20mm); amplification
  3. alpha angle: slope between R and K; measures the speed at which fibrin build up and cross linking takes place, hence assesses the rate of clot formation; thrombin burst
  4. MA: maximum amplitude (mm); represents the ultimate strength of the fibrin clot; clot strength
  5. LY-30: amplitude at 30 minutes; percentage decrease in amplitude at 30 minutes post-MA; fibrinolysis
45
Q

What are the treatment options availible for different TEG traces?

A
  • Increased R time => FFP
  • Decreased angle => cryopreciptate
  • Decreased MA => platelets (consider DDAVP)
  • Fibrinolysis => tranexamic acid (or aprotinin or aminocaproic acid)
46
Q

What does this trace show?

A

Hypercoagulability

  • R and K Decreased
  • Angle and MA Increased
47
Q

What does this trace show?

A

Hyperfibrinolysis

  • R and K normal
  • MA normal or continuously decreasing
  • LY-30 > 7.5%
48
Q

What does this trace show?

A

DIC Stage 1

  • R, K, Alpha, MA Increased
  • LY-30 Increased (Secondary fibrinolysis)
49
Q

What characteristics will platelet dysfunction show on TEG?

A
  • Normal R (normal initiation)
  • Decreased K (slow amplification)
  • Decreased MA
  • Normal LY-30
50
Q

Describe the blood supply to the heart

A
  • Right and Left coronary arteries branch from the aorta
  • The left coronary artery divides itself into:
    • Left anterior descending artery (LAD)
    • Ramus circumflexus (RCX)
  • The right coronary artery (RCA) connects to the ramus descendens posterior (RDP)
  • In 20% of the normal population the RDP is supplied by the RCX (left dominance)
51
Q

Describe the ECG findings for an anterior MI

A
  • ST Elevation in:
    • V1-V6
  • Reciprocal ST Depression in:
    • Nill
  • Coronary artery teritory
    • LAD
52
Q

Describe the ECG findings for a septal MI

A
  • ST Elevation in:
    • V1-V4, disappearance of septum Q in leads V5,V6
  • Reciprocal ST Depression in:
    • Nill
  • Coronary artery teritory
    • LAD-septal branches
53
Q

Describe the ECG findings for a lateral MI

A
  • ST Elevation in:
    • I, aVL, V5, V6
  • Reciprocal ST Depression in:
    • II,III, aVF
  • Coronary artery teritory
    • LCX or MO
54
Q

Describe the ECG findings for an inferior MI

A
  • ST Elevation in:
    • II, III, aVF
  • Reciprocal ST Depression in:
    • I, aVL
  • Coronary artery teritory
    • RCA (80%) or RCX (20%)
55
Q

Describe the ECG findings for a posterior MI

A
  • ST Elevation in:
    • V7, V8, V9
  • Reciprocal ST Depression in:
    • high R in V1-V3 with ST depression V1-V3 > 2mm (mirror view)
  • Coronary artery teritory
    • RCX
56
Q

Describe the ECG findings for a Right Ventricle MI

A
  • ST Elevation in:
    • V1, V4R
  • Reciprocal ST Depression in:
    • I, aVL
  • Coronary artery teritory
    • RCA
57
Q

Describe the ECG findings for an atrial MI

A
  • ST Elevation in:
    • PTa in I,V5,V6
  • Reciprocal ST Depression in:
    • PTa in I,II, or III
  • Coronary artery teritory
    • RCA
58
Q

What is a CM5 ECG configuration?

A

CM5 detects 89% of ST-segment changes due to left ventricular ischaemia. (Right arm electrode on manubrium, left arm electrode on V5 and indifferent lead on left shoulder).

59
Q

What is a CB5 ECG confirguration?

A

CB5 is useful in thoracic anaesthesia. Right arm electrode over the centre of the right scapula and left arm electrode over V5.

60
Q

What ppoFEV1/ppoTLCO should prompt for further investigations.

A

Less than 40%

61
Q

A patient undergoing pneumonectomy has a ppoFEV1 less than 40%, which investigation is most appropriate?

A

CPET

62
Q

What is the cut off VO2 Max on CPET for pneumonectomy?

A

Less than 15 ml/kg/min would be of concern

63
Q

Grades of AS

A
  • Mild: area < 1.5cm2, gradient < 25 mmHg
  • Moderate: 1-1.5cm2, gradient 25-40 mmHg
  • Severe: < 1cm2, gradient >40 mmHg
  • Critical: area < 0.6cm2, gradient > 70 mmHg
64
Q

What is the blood supply to the sino-atrial and atrio-ventricular nodes?

A
  • SAN - 2/3rds by right coronary
  • AVN - Majority by right coronary

FRCA Final (21 decks)

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