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Diploma in Anaesthesia > Risk, consent and preop assessment in CVS and RSP disease > Flashcards

Risk, consent and preop assessment in CVS and RSP disease Flashcards

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1
Q

How can very common/common/uncommon/rare/very rare be described to a patient during the consent process

A

Very common - 1 in 10 (One person in your family)
Common - 1 in 100 (One person on your street)
Uncommon - 1 in 1000 (One person in a village)
Rare - 1 in 10 000 (One person in a town)
Very rare - 1 in 100 000 (One person in a city)

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2
Q

Describe the common side effects of regional and general anaesthesia

A

GA + RA

PONV
Dizziness
Headache
Itching
Aches and pains
Pain at injection areas
Bruising and soreness

GA
Sore throat
Confusion and memory loss

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3
Q

Describe the uncommon side effects to GA and RA

A

GA + RA

Bladder problems
Slow breathing
Worsening of existing medical problem

GA
Chest infection
Damaged teeth/tongue/lips
Awareness

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4
Q

Describe the rare side effects to GA

A

GA + RA

Serious allergy to drugs
Nerve damage
Death
Equipment failure

GA
Eye damage

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5
Q

Who makes the decision regarding capacity

A

The health professional proposing the treatment

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6
Q

Can an anaesthetist refuse a Jehovah’s witness in the elective situation?

A

Yes but he must refer the case to a suitably qualified colleague who is prepared to do the case

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7
Q

In what situations might a Jehovahs witness accept blood products for transfusion

A
  • Autologous (cell-saver) blood
  • Cardiopulmonary bypass with non-hematogenous primes
  • Epidural blood patch may be acceptable to some
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8
Q

Should blood be given to the child of a Jehovah’s witness in a life-threatening emergency when the child is unable to give competent consent against the wishes of the parents

A

Yes.

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9
Q

List the ways of minimizing awareness during anaesthesia

A
  1. Choose LA/RA and stay awake
  2. Pre-op - Equipment check
  3. Pre-op monitoring check (pt, disconnection alarms, drug monitoring)
  4. Brain activity monitors
  5. Avoid muscle relaxants –> awareness is less common in spontaneously breathing patients
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10
Q

How common is awareness and what proportion feel pain

A

1 in 1000 have some degree of awareness

1 in 3000 feel pain

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11
Q

What are the reasons for awareness

A

Misjudgement of anaesthetic doses needed or equipment malfunction

High risk operations (for awareness)

  • Caesarian section (attempt to avoid drugs affecting baby)
  • Emergency surgery (severe illness)
  • Cardiac surgery

Chronic opioids/ETOH

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12
Q

Compare the benefits of GA vs benefits of RA

A

Benefits of RA

  1. Postoperative analgaesia (epidural)
  2. Decreased blood loss
  3. Decreased risk VTE
  4. Decreased PONV
  5. Reduced chest infection risk
  6. Earlier return to eating and drinking

Benefits of GA
1. Unconscious during surgery
(analgaesia available post op: PCA/IM/PO/PR)

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13
Q

What are the two major causes of mortality in the first 28 days after surgery and why is this the case

A

Cardiac (59%)
Respiratory (35%)

O2 consumption after surgery can increase by up to 40%. Any disease which affects the cardiac and respiratory systems may mean that the patient is unable to increase oxygen delivery to meet the increased demand.

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14
Q

Stratify cardiovascular risk based on history and examination

A

High risk

IHD
- MI < 3 month
- Unstable angina
Decompensated heart failure
Arrhythmias (symptomatic/uncontrolled)
Severe AS or MS

Intermediate risk

  • Previous MI
  • Stable angina Compensated HF
  • Previous stroke
  • DM
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15
Q

Describe metabolic equivalents

A

1 metabolic equivalent (or MET) is equal to the oxygen consumed by an individual at rest and during normal activity. In a 70 kg male this equates to an O2 consumption of about 250 ml/min.

2-3 METS: light house work

4 METS: Climbing one flight of stairs/running a short distance

> 10 METS: highly strenuous sport: tennis/soccer

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16
Q

When can METS not be assessed

A

Patient’s with limited mobility

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17
Q

When does heart failure occur

A

When the heart is unable to provide adequate tissue perfusion in the presence of normal filling pressures.

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18
Q

What is the mortality rate for a patient with decompensated heart failure - undergoing a high risk operation such as an emergency laparotomy?

A

20 -30%

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19
Q

Describe the pathophysiology of angina and at what level of narrowing of the coronary artery lumen this occurs

A

O2 extraction in the heart is very high at rest (OER = 0.6)
Exercise/stress –> increased myocardial O2 demand which is normally met by increased coronary blood flow. But this is not possible in atherosclerosis and the onset of angina usually occurs when lumen obstruction approaches 70%

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20
Q

How do MIs occur in the perioperative period?

A

O2 demand supply imbalance

50% are caused by excessive demand: Major surgery, stress, pain –> SNS –> tachycardia and hypertension –> increased O2 demand

50% are caused by sudden reduced supply: Unstable atherosclerotic plaque haemorrhage/rupture causing thrombosis and occlusion

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21
Q

In what % of patients over 65 is valvular heart disease diagnosed and what is the most common type

A

4%

Aortic stenosis

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22
Q

Aortic stenosis and mitral stenosis versus regurgitant valve disease: which condition tolerates anaesthesia and which condition is very high risk for anaesthesia and why

A

Aortic stenosis and mitral stenosis: Very high risk as they are associated with a fixed cardiac output state and are unable to compensate for falls in SVR or increase the metabolic demands caused by the stress of major surgery

Regurgitant valve disease often tolerate anaesthesia well –> reduction in SVR reduces regurgitant fraction and improves forward flow

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23
Q

How can severity of stenotic valve lesions be quantified

A

Doppler echocardiography: identifies increased flow velocity across stenotic valves from which pressure gradients and severity of stenosis may be estimated

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24
Q

What happens if patients with aortic stenosis develop tachycardia or lose sinus rhythm?

A

Usually calcification –> increased afterload –> LVH –> decreased LV wall compliance –> atrial contractions now contribute 40% (instead of 20%) to ventricular filling

Therefore:

  • Tachycardia is poolry tolerated
  • Loss of sinus rhythm may cause a critical reduction in cardiac output
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25
Q

Why can aortic stenosis be associated with angina in the absence of coronary artery disease

A

Due to left ventricular hypertrophy and fixed CO state

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26
Q

What are the symptoms of aortic stenosis

A

Angina
Effort syncope
Dyspnoea

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27
Q

What are the signs of aortic stenosis

A

EJECTION OF FLOW RESTRICTED

  • Slow rising pulse
  • Reduced pulse pressure
  • Ejection systolic murmur
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28
Q

What is the normal aortic valve area?

A

2.6 - 3.5 cm^2

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29
Q

Classify the severity of aortic stenosis

A

MILD

  • Valve area: >1.5 cm^2
  • Mean gradient: <25 mmHg

MODERATE

  • Valve area: 1.0 - 1.5 cm^2
  • Mean gradient: 25 - 40 mmHg

SEVERE

  • Valve area: < 1.0 cm^2
  • Mean gradient: > 40 mmHg
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30
Q

What are the symptoms of mitral stenosis

A

Dyspnoea, palpitations, fatigue.

If pulmonary hypertension develops:

  • bronchitis
  • haemoptysis
  • pulmonary oedema
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31
Q

What happens if patients with mitral stenosis develop tachycardia or lose sinus rhythm?

A

Critical decrease in cardiac output –> acute pulmonary oedema

32
Q

What is the normal valve area of the mitral valve

A

4 - 6 cm^2

33
Q

Classify the severity of mitral stenosis

A

MILD
- Valve area: 1.5 - 2.5 cm^2

MODERATE
- 1.0 - 1.5 cm^2

SEVERE
- <1.0 cm^2

34
Q

Describe the management of pre-operative (non-cardiac surgery) patients with AORTIC stenosis

A

SYMPTOMATIC:
AV replacement prior to major elective surgery

ASYMPTOMATIC:
Major surgery (with marked fluid shifts) thoracic/abdominal/major orthopedic
with AV gradients > 40 mmHg –> referred for AV replacement

Intermediate or minor surgery
–> do well if managed carefully with invasive monitoring

35
Q

Describe the management of pre-operative (non-cardiac surgery) patients with MITRAL stenosis

A

SYMPTOMATIC:
MV replacement considered prior to major elective surgery

ASYMPTOMATIC:
Usually tolerate elective surgery well

36
Q

Define atrial fibrillation

A

Arrhythmia
Uncoordinated atrial activation
Poor atrial mechanical function
Irregular ventricular response

37
Q

Why is cardiac output reduced in patients with AF

A

Well timed atrial contraction normally contributes 20% of ventricular filling

38
Q

What are the common causes of AF

A

Majority: Idiopathic AF

IHD
MV disease
Thyrotoxicosis

39
Q

What is the greatest risk associated with AF

A

Arterial thromboembolism (Clots forming in the left atrium)

  • Stroke
  • Acute gut ischaemia
  • Acute limb ischaemia
40
Q

How does anticoagulation with warfarin change the risk of stroke in atrial fibrillation

A

It halves the risk of stroke

41
Q

List the three important aspects of perioperative AF management

A
  1. Rate control < 100 (improves LV filling and reduces O2 demand)
  2. Anticoagulation: Warfarin should be stopped four days prior to surgery (minimal risk of bleeding when INR< 1.5)
  3. ECHO: for patients with functional impairment
    - Quantify ventricular performance
    - Measures left atrial size
    - Identifies Mitral Valve disease
42
Q

Under what circumstances can elective surgery proceed in the poorly controlled hypertensive patient

A

BP < 180/110 and NO TARGET ORGAN DAMAGE

Hypertension in the absence of target organ damage does not increase perioperative CVS complications

43
Q

What should be done if the BP for the patient is > 180/110 in the patient awaiting elective surgery

A

Delay surgery for four weeks and control BP

44
Q

Which patients with a newly diagnosed murmur should have an ECHO

A

Ideally all patients

> 4 METS, N ECG, N CXR –> tolerate minor and intermediate surgery but will require ECHO if major surgery is planned

Any patient with < 4 METS (poor functional capacity) –> ECHO

45
Q

What are the respiratory complication rates of body cavity surgery (thoracic and upper abdominal) and why is this the case

A

20 - 40% (compared to 2 - 5% in lower abdominal surgery)

46
Q

What happens to FRC during general anaesthesia and why

A

Decreases by 20%

Supine + muscle relaxation
Upward displacement of diaphragm downward displacement of lower ribs.

47
Q

What can potentially reduce pulmonary complications in major abdominal surgery

A

Effective epidural anaesthesia

48
Q

Describe the common causes of COPD

A

Congenital
- alpha 1 antitrypsin deficiency

Acquired

  • cigarette smoking
  • other fumes/dusts
49
Q

Define Chronic Bronchitis

A

Chronic Bronchitis is characterised by breathlessness and a productive morning cough for at least 3 months of the year in two consecutive years

Productive morning cough x3 months for two consecutive years

50
Q

Describe the pathophysiology of chronic bronchitis

A

Small airway obstruction is caused by mucosal oedema, mucus hypersecretion secondary to glandular hypertrophy.

51
Q

Describe the common clinical characteristics associated with chronic bronchitis

A

“Blue bloaters”

Overweight
Poor respiratory effort
Chronic CO2 retention
Hypoxaemia
Pulmonary hypertension
Right Ventricular Failure
52
Q

Define emphysema

A

Progressive and irreversible expansion of alveoli with eventual destruction o the alveolar tissue.

53
Q

What causes small airway obstruction in emphysema

A

Loss of elastic recoil of small airways which normally holds the airways open during expiration

54
Q

Describe the clinical features of emphysema

A

“Pink puffers”

Thin
Maintain reasonable oxygenation
Increased VE
Always SOB

55
Q

Define asthma

A

Recurrent reversible episodes of airway obstruction, caused by mucosal swelling, mucus hypersecretion and bronchoconstriction

56
Q

What is extrinsic and intrinsic asthma

A

Extrinsic –> in response to an external allergen

Intrinsic –> occurs in adults and has overlap with COPD

57
Q

How are well controlled asthmatics managed in the perioperative phase

A

Good control –> tolerate anaesthesia well

Poor control –> tolerate anaesthesia poorly

Continue all medications if controlled or change or add to get control

B2 agonist (Salbutamol)
Antimuscarinic (ipratroprium bromide)
Inhaled Steroids (Beclometasone)
58
Q

How are poorly controlled asthmatics managed in the perioperative period

A

Preoperative steroids (prednisolone 30 -60 mg daily x 4-5 days)

If already taking > 10mg prednisolone daily (very poor control) –> supplement hydrocortisone perioperatively

Exclude chest infection

59
Q

What effects does smoking have on the airways

A
  1. Sensitised/irritable airway (smokers cough)
  2. Increased mucus production (chemicals inhaled)
  3. Impaired ciliary function (secretion clearance reduced)
  4. Narrowed airways
    - reflex bronchoconstriction (chemicals)
    - increased mucus production (chemicals)
60
Q

What occurs more commonly during anaesthetics in smokers?

A
  1. Bronchospasm
  2. Laryngospasm
  3. Coughing
  4. O2 desaturation
  5. Postoperative chest infection
  6. Reduced O2 carrying capacity (COHb 2 -12%)
  7. SNS activation by nicotine
61
Q

How long before surgery should smoking be discontinued to reduce morbidity from complications to that of non-smokers

A

8 weeks

62
Q

How does smoking affect the oxygen carrying capacity. How can this be mitigated

A

Reduces the oxygen carrying capacity as levels of COHb are between 2 - 12% (normal <1.5%)

Abstinence for 12 hours will improve O2 carrying capacity (T1/2 of COHb is 4h) and reduce SNS activation by nicotine (t1/2 < 60 min)

63
Q

How is the FEV1/FVC ratio interpreted?

A

FEV1/FVC < 70% in obstructive lung disease

FEV1/FVC > 70% in restrictive lung disease (Normal is 80%)

If measurements indicate an obstructive pattern then the measurements should be completed again 10 minutes after an inhaled bronchodilator

64
Q

How is PEFR interpreted in an anaesthetic context?

A

Coughing is ineffective when PEFR < 200 L/min

PEFR falls during obstructive episodes

65
Q

How are the absolute values of FEV1 and FVC interpreted in an anaesthetic context?

A

FEV1 of less than 0.8 L and a FVC of less than 1 liter indicates that the patient’s cough will be poor and suggests the likely need for respiratory support following major surgery

66
Q

What is the name of the instrument used to measure the FEV1 and the FVC

A

Vitalograph - plots expired volume versus time

67
Q

What is DLCO

A

Another name for DLCO is transfer factor

This is the carbon monoxide diffusing capacity - it is an indication of the efficiency of gas exchange across the alveolar capillary membrane.

CO is extremely soluble in blood and hence never reaches equilibrium with capillary blood. This means that diffusion is independent of perfusion and hance CO is used because the amount that diffuses into the blood reflects the diffusion capacity rather than the pulmonary perfusion

68
Q

What diseases reduce DLCO

A

Interstitial lung diseases

Pulmonary fibrosis
Scleroderma
Sarcoidosis

All increase the thickness of the alveolar capillary membrane and hence reduce the DLCO

69
Q

What happens to the DLCO in emphysema and why?

A

In reduces. Alveolar destruction leads to a reduced surface area for gas exchange

70
Q

How can the DLCO be interpreted in an anaesthetic context?

A

DLCO of less than 60% predicted is associated with increased risk of pulmonary complications after major surgery

71
Q

What are CXR findings in pulmonary fibrosis

A

Bilateral ground glass appearance

72
Q

When should an ABG be performed preoperatively?

A

Patients breathless on minimal exertion
Hypoxic on room air
To look for CO2 retention
To quantify degree of hypoxia

73
Q

Summarise the criteria indicating severe respiratory disease

A

Breathlessness on minimal exertion

Hypoxia on room air (SaO2<95%)
PaCO2 > 6.0 kPa

FEV1 < 0.8 L
FVC < 1 L
DLCO < 60%

74
Q

What should the postoperative plan for patients with indications of severe respiratory disease include?

A

Initial postoperative care should be in HDU/ICU

If postoperative ventilatory support becomes necessary, non-invasive ventilation can be considered

75
Q

Is coronary sinus blood oxygen content the same as mixed venous blood?

A

Mixed venous blood O2 content = 15ml O2/100ml blood

Coronary sinus blood O2 content = 9 ml O2/100ml blood

Myocardium has an OER of 0.6 compared to peripheral tissue of 0.75

Diploma in Anaesthesia (73 decks)

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