Specific diseases Flashcards by Ra Ma

What are the criteria of the STOP-BANG assessment?

Snoring
Tiredness during the day
Observed cessation in breathing
Pressure (BP) high
BMI >35 kg/m2
Age >50
Neck circumference >40cm
Gender male

≤ 2 - excludes OSA
3-4 - intermediate risk of OSA
≥ 5 - high risk of OSA

How well did you know this?

Not at all

Perfectly

What is the AHI?

Apnoea-Hypopnoea Index
The number of apnoeas or hypopnoeas lasting >10s recorded in 1 hour

≥5 mild
≥15 moderate
≥30 severe

How well did you know this?

Not at all

Perfectly

What constitutes a significant desaturation in OSA?

Desaturations >4% if ≥5 in 1 hour

How well did you know this?

Not at all

Perfectly

Which features of OSA does nocturnal CPAP most improve? (3)

CCF
Platelet aggregation
Dysrhythmias

How well did you know this?

Not at all

Perfectly

Which features of OSA should prompt to postpone surgery and optimise?

Untreated CCF
Hypercapnoea with PaCO₂ >6.5

How well did you know this?

Not at all

Perfectly

What is the most common and most severe muscular dystrophy?

Duchenne Muscular Dystrophy (DMD)

How well did you know this?

Not at all

Perfectly

What is the incidence of DMD?

1 in 3500 male live births (LB)

How well did you know this?

Not at all

Perfectly

Define muscular dystrophy

Inherited disorder characterised by progressive muscle weakness, without evidence of denervation
Caused by mutations in genes (usually those involved in making muscle proteins)
X-linked recessive

Post-junctional neuromuscular disorder

Dystrophy = tissue degeneration
Muscular dystrophy = muscular tissue degeneration

Progressive muscular weakness, pseudohypertrophy (muscle contractures), poor balance, progressive inability to walk, scoliosis, waddling gait, Gowers’ sign

How well did you know this?

Not at all

Perfectly

What are the cardiac effects of DMD? (3)

Cardiomyopathy
Arrhythmias
Conduction defects
Heart failure

How well did you know this?

Not at all

Perfectly

What are the respiratory effects of DMD? (4)

Respiratory muscle weakness
Swallowing impairment
Improper secretion management
Recurrent chest infections
Scoliosis resulting in restrictive lung defects
Failure to wean from ventilation

How well did you know this?

Not at all

Perfectly

What are the neurological effects of DMD?

Learning disability

How well did you know this?

Not at all

Perfectly

What is the typical life expectancy in DMD?

15-25 years

How well did you know this?

Not at all

Perfectly

What is pseudohypertrophy?

False enlargement of muscle

Dystrophin absence renders sarcolemma weak → muscle fibres inadequately tethered → replaced with fibrous connective tissue → pseudohypertrophy

How well did you know this?

Not at all

Perfectly

What are the biochemical abnormalities found in DMD?

Raised CK

How well did you know this?

Not at all

Perfectly

What are the common operations in DMD?

Orthopaedic:
Scoliosis corrections

Cardiac:
Angiography
Valve replacement

Ophthalmic:
Cataracts

Incidental:
Dental work 2° to low IQ

How well did you know this?

Not at all

Perfectly

Why should you perform lung function tests in DMD?

FVC <20ml/kg associated with increased mortality

How well did you know this?

Not at all

Perfectly

List 3 acquired, non-drug related causes of Long QT

Subarachnoid haemorrhage
Anorexia Nervosa
Hypothermia
Hypocalcaemia
Hypokalaemia

How well did you know this?

Not at all

Perfectly

How do you diagnose long QT?

QTc greater than 450 ms men, 460 ms women

How well did you know this?

Not at all

Perfectly

What is your perioperative anaesthetic management of Long QT?

Seek cardiologist opinion
Check electrolytes
Perform ECG with valsalva
Stop any drugs that increase QTc
Continue beta blockers
Avoid suxamethonium
Obtund pressor response to laryngoscopy
Avoid use of reversal (use sugammadex)
Consider transvenous pacing

How well did you know this?

Not at all

Perfectly

Pathophysiology of long QT?

Depolarisation abnormality
Malfunction in cardiac ion channels

How well did you know this?

Not at all

Perfectly

What is porphyria?

Group of disorders characterised by an inherited or acquired abnormality in the enzymes relating to haem synthesis

How well did you know this?

Not at all

Perfectly

What is the pathophysiology of porphyria?

Failure in haem synthesis → accumulation of porphyrins and precursors (ALA, aminolaevulinic acid, and PBG, porphobilinogen)

Which enzyme is an important rate limiting step in porphyria?

ALA synthetase

What is the incidence of porphyria?

1 in 20,000

How is a diagnosis of porphyria confirmed?

Urinary ALA and porphobilinogen (PBG)

What are the different types of porphyria?

Acute Hereditary Intermittent Variagate

Which premedication drugs are considered SAFE in porphyria?

NONE

Which induction agents are considered SAFE in porphyria?

Propofol only

Which maintenance agents are considered SAFE in porphyria?

Most volatiles N₂O

Which analgesics are considered SAFE in porphyria?

Paracetamol Aspirin Codeine Opioids: Fentanyl Alfentanil Morphine Pethidine

Which local anaesthetics are considered SAFE in porphyria?

Bupivacaine Prilocaine

Which uterotonics are considered SAFE in porphyria?

Oxytocin

Define BMI

Body mass index, kg/m2 Mass / height^2

What is the WHO BMI classification?

Underweight <18.5 Healthy weight: 18.5-24.9 Overweight: 25-29.9 Obesity: 30+ - Class 1 Obesity: 30-34.9 - Class 2 Obesity: 35-39.9 - Class 3 Obesity: 40+ (morbid)

What is morbid obesity?

BMI > 40, or BMI > 35 with a recognised co-morbidity: - T2DM - Sleep disordered breathing - HTN - Cardiovascular disease - Cerebrovascular disease

Define central obesity

Waist circumference > 88 cm in a woman Waist circumference > 102 cm in a man; or a waist-to-height ratio > 0.55

What risks is OSA specifically associated with in the perioperative period? (4)

OSA patients have double the incidence of: - Postoperative desaturation - Respiratory failure - Postoperative cardiac events - ICU admission

What is obesity hypoventillation syndrome?

A triad of: 1. Obesity (BMI > 35) 2. Sleep disordered breathing (usually OSA) 3. Daytime hypercapnoea (PaCO₂ > 6 kPa)

What is the typical compliance with nocturnal CPAP for OSA?

Around 50%

Obesity Hypoventilation Syndrome - pathophysiology (3)

Leptin intolerence / resistance Reduction in CO₂ chemoreceptor sensitivity Particularly susceptible to opioid respiratory depression

What are the cardiovascular sequelae of obesity? (5)

HTN Increased cardiac output and cardiac work Pulmonary HTN CCF Arrhythmias - 2° to sino-atrial node dysfunction and fatty infiltration of the conducting system - 1.5x RR for atrial fibrillation - Increased risk of sudden cardiac death - Increased incidence of prolonged QT interval

Which anaesthetic drugs should be dosed on Lean Body Weight?

Induction agents - Propofol (induction) - Thiopental - Fentanyl Non-depolarising Muscle Relaxants: - Rocuronium - Atracurium - Vecuronium Morphine Paracetamol Bupivacaine Lidocaine

Which anaesthetic drugs should be dosed on Adjusted Body Weight

Propofol (infusion) Antibiotics Low molecular weight heparin Alfentanil Neostigmine (maximum 5 mg) Sugammadex

Ideal Body Weight

IBW = height (cm) - x x = 105 in females x = 100 in males

Lean Body Weight

The patient’s weight excluding fat Many of the formulae for calculating lean body weight are complex but one of the most widely used is that of Janmahasatian et al.

Adjusted Body Weight

ABW = IBW + 0.4(TBW - IBW) Adding 40% of the excess weight to the IBW

What is OS-MRS?

Obesity Surgery Mortality Risk Stratification: BMI > 50 Male Age > 45 years Hypertension Risk factors for pulmonary embolism - Previous VTE - Venocaval filter - Sleep disordered breathing - Pulmonary HTN Mortality: Class A: 0-1 points: 0.2-0.3% Class B: 2–3 points: 1.1-1.5% Class C: 4–5 points: 2.4-3%

What are the main benefits of a pre-operative discussion in bariatric surgery?

Promote smoking cessation Discuss importance of VTE-prophylaxis and early mobilisation Plan management of medication before admission Remind patients to bring their own CPAP machine Commence “Liver Shrinking” diet Ensure CPAP adherence

What collar size is associated with a difficult airway?

> 43cm

How much epidural catheter should be left in the space in bariatric cases

At least 5 cm to prevent catheter migration

Why might suxamethonium be a bad idea in bariatric cases?

Suxamethonium associated fasciculations increase oxygen consumption and have been shown to shorten the safe apnoea time It is unlikely to wear off before profound hypoxia occurs

List some general techniques to deliver a “Safe Sleep-Disordered-Breathing Anaesthetic”

Avoid GA/Sedatives where possible Use short acting agents Use DoA monitoring to limit anaesthetic load Use neuromuscular monitoring to ensure complete reversal of block before waking Maximal use of local anaesthetic and multimodal opioid sparing analgesia Maintain head–up position throughout recovery Monitor of oxygen saturations until mobile Reinstate CPAP early

Describe the basic pathophysiology of acromegaly

Eosinophilic adenoma Excess growth hormone production