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Med Yr2 > Breathlessness > Flashcards

Breathlessness Flashcards

1
Q

Hypoxaemia (hypoxic hypoxia):

A
  • Abnormally low arterial partial pressure of oxygen (PaO2)
  • Associated with clinical signs of central cyanosis
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2
Q

Hypoxia:

A
  • Low tissue partial pressure of oxygen. Either due to a reduced O2 supply or inability to utilise it
  • Hypoxaemia is one, but not the only, cause of hypoxia
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3
Q

Alveolar-arterial (Aa) difference:

A

Aa difference = PAO2 - PaO2
- PA02: calculated using the alveolar gas equation
- PaO2 is measured via blood gas analysis

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4
Q

How to find PAO2 and PaO2:

A
  • PA02: calculated using the alveolar gas equation
  • PaO2 is measured via blood gas analysis
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5
Q

Aa difference: healthy ranges
- Healthy subjects
- Elderly

A
  • 2 KPa
  • 5 KPa
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6
Q

Causes of tissue hypoxia: Hypoxaemia

A
  • Hypoxaemia leads to a decrease in total oxygen content by lowering oxygen saturation (SaO2) and partial pressure of arterial oxygen (PaO2)
  • Total content (C) = (O2 binding capacity X SaO2) + (PaO2X solubility)
  • Rate of O2 delivery = Cardiac output (Q) X O2 content (C)
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7
Q

Causes of tissue hypoxia: stagnant hypoxia

A
  • Cardiac output is insufficient due to cardiac failure at normal filling pressures
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8
Q

Causes of tissue hypoxia: Anaemic hypoxia (2)

A
  • Rate of O2 delivery is reduced by a decrease in O2 content, this is due to a reduction in oxygen binding capacity
  • This reduced O2 binding capacity is caused by a reduction in viable RBCs
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9
Q

Causes of tissue hypoxia: histotoxic hypoxia
- Explanation (2)
- Cause

A
  • Rate of O2 delivery is normal but the tissues are unable to utilise the O2
  • Causes elevated CvO2 and a low arteriovenous difference in blood O2 content
  • Classic cause is cyanide poisoning (also smoke inhalation)
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10
Q

Alveolar ventilation equation:

A
  • PACO2 = PaCO2 § Rate of CO2 production by metabolism / Rate of CO2 removal by AV
  • PACO2 is directly proportionate to CO2 production rate and inversely proportionate to Rate of CO2 removal by AV
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11
Q

Type 2 respiratory failure:

A
  • “Pump failure”: CO2 production rate remains constant, hypoventilation causes hypercapnia (+PaCO2)
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12
Q

Clinical features of type 2 respiratory failure: (4)

A
  • vary according to underlying cause
  • Headache (cerebral vasodilation)
  • Flapping tremor of wrist
  • Bounding pulse
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13
Q

Type 1 respiratory failure:

A
  • When the respiratory system is unable to supply the body with an adequate amount of oxygen
    (lower PaO2)
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14
Q

Heart failure definition: (2)

A
  • An inability of the heart to maintain an adequate perfusion of the tissues (cardiac output) at a normal filling pressure
  • It is not a diagnosis but a syndrome of signs and symptoms caused by a variety of pathological conditions
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15
Q

Pathophysiology of Chronic Left-sided Heart Failure:
- Systolic dysfunction (emptying): (2)

A
  • Impaired emptying due to reduced contractility and/or increased afterload
  • End-systolic volume is increased due to the reduction in stroke volume and ejection fraction
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16
Q

Impaired contractility causes: (3)

A
  • MI or ischaemia
  • Dilated cardiomyopathy
  • Chronic “volume overload” e.g. mitral or aortic regurgitation
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17
Q

Excessive afterload cause: (3)

A
  • Aortic stenosis: narrowing of the aortic valve outlet
  • May result in a slow rising pulse and an ejection systolic murmur in aortic area
  • Systemic hypertension (+TPR)
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18
Q

Physiology of chronic left-sided heart failure:
- Diastolic dysfunction:

A
  • Increased stiffness of the ventricle impairs filling during diastole
  • Fibrosis and hypertrophy of ventricular wall or pericardium constriction
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19
Q

Right-sided heart failure:
- Definition
- Causes

A
  • Right ventricle fails if the afterload is too high
  • Secondary to LVF (commonest), Cor pulmonale, Acute PE, pulmonary stenosis
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20
Q

Cor pulmonale:
- Definition
- Symptoms (6)

A
  • RHF due to hypoxic lung disease (COPD)
  • Central cyanosis, raised JVP, pitting oedema, hepatomegaly, Parasternal heave (RVH), tricuspid regurgitation
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21
Q

Compensatory mechanisms for CHF:
- Increased renal salt …..

A
  • Increased renal salt and water retention leading to
    increased filling pressures (↑JVP) and (hopefully!)
    stroke volume by Frank-Starling mechanism
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22
Q

Compensatory mechanisms for CHF:
- Baroreceptor …..

A
  • Baroreceptor reflex increases sympathetic tone
    increasing heart rate and contractility and producing
    increased peripheral vasoconstriction with a relative
    diversion to the coronary and cerebral circulations
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23
Q

Compensatory mechanisms in CHF:
- Heart

A
  • Ventricular hypertrophy (LVH) and remodelling
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24
Q

What causes the increase in filling pressure?: (3)

A
  • Renin-angiotensin-aldosterone system
    The release of renin is stimulated by
    (1) Reduced renal artery pressure secondary to the fall in cardiac
    output
    (2) Increased renal sympathetic tone (due to baroreceptor reflex)
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25
Q

Detrimental effects of increased filling pressures (4)

A
  • A dilated heart is less efficient at contracting (Law of Laplace)
  • Widening of the atrioventricular valve orifices leads
    to regurgitation of blood through the valves
  • Increased filling pressure of the left ventricle leads
    to pulmonary oedema and breathlessness
  • Increased filling pressure of right ventricle leads to
    peripheral pitting oedema
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26
Q

Increased sympathetic tone: friend or foe?

A
  • Probably beneficial in mild failure but in more severe cases the effects can be detrimental
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27
Q

Increased sympathetic tone: detrimental effects (3)

A
  1. Venoconstriction raises the filling pressure
  2. Vasoconstriction leads to increase in afterload and
    hence myocardial oxygen consumption
  3. Uncoupling and down regulation of beta 1
    receptors reduces the positive inotropic effects of
    sympathetic stimulation
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28
Q

Signalling molecules increased in plasma in HF: (3)

A
  • ADH: Promotes water retention by kidney.
  • Endothelin: Potent vasoconstrictor (future therapeutic target?)
  • BNP: B-type natriuretic peptide
    produced by failing myocardium
    Plasma levels correlate with degree
    of severity, used as a biomarker
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29
Q

Ventricular hypertrophy and remodelling: (2)

A
  • Chronic elevations in wall stress and neuro-humoral factors lead to remodelling
  • The associated decrease in compliance leads to increased diastolic filling pressures
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30
Q

How does cardiac failure produce oedema?: (3)

A
  • Increased venous filling pressure increases capillary pressure
  • Salt & water retention reduces conc. of proteins in plasma and decreases colloid osmotic pressure in plasma
  • This increases production of tissue fluid by capillaries by ultrafiltration
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31
Q

Heart failure signs: dysponea and orthopnoea

A
  • Dysponea: Abnormal feeling of need to breath due to pulmonary venous congestion
  • Othopnoea: Breathlessness upon laying flat due to redistribution of blood from lower limbs
32
Q

Heart failure signs: PND and fatigue

A
  • PND: Paroxysmal nocturnal dysponea, wakes patient from sleep. Gradual reabsorption of peripheral oedema fluid when laying flat
  • Fatigue: reduced perfusion of skeletal muscle
33
Q

Signs of acute LVF: (4)

A
  • Tachypnoea: Due to stimulation of J receptors
  • Cold hands: Due to increased sympathetic tone
  • Tachycardia: Due to increased sympathetic tone
  • Crackles or wheeze: Due to pulmonary oedema
34
Q

Breathlessness investigations: Lungs
- Full Blood Count
Result
Possible diagnosis

A
  • Raised WCC
  • Possible infection
35
Q

Breathlessness investigations: Lungs
- BNP
Result
Possible diagnosis

A
  • > 400pg/mL
  • Heart failure if over, if under then rule out
36
Q

Breathlessness investigations: Lungs
- U & E
Result
Possible diagnosis

A
  • Increased urea and creatinine
  • Acute kidney injury which can cause breathlessness via several mechanisms
37
Q

Breathlessness investigations: Lungs
- D-dimer
Result
Possible diagnosis

A
  • Positive
  • DVT/PE, if negative then rule out
38
Q

Breathlessness investigations: Lungs
- ABG
Result
Possible diagnosis

A
  • Respiratory acidosis/alkalosis
  • Many, including COPD, severe asthma, panic attack
39
Q

Breathlessness investigations: Lungs
- CRP
Result
Possible diagnosis

A
  • Raised
  • inflammation, non-specific infection, blood cultures needed
40
Q

Breathlessness investigations: circulation
- FBC
Result
Possible diagnosis

A
  • Decrease in Hb
  • Anaemia, further tests needed to distinguish the type
41
Q

Breathlessness investigations: circulation
- Troponin
Result
Possible diagnosis

A
  • Positive
  • Myocardial damage
42
Q

Breathlessness investigations: circulation
- Carboxyhaemoglobin
Result
Possible diagnosis

A
  • Raised
  • CO poisoning
43
Q

Breathlessness investigations: circulation
- Methaemoglobin
Result
Possible diagnosis

A
  • Raised
  • Congenital, drugs
44
Q

Breathlessness investigations: circulation
- LFTs
Result
Possible diagnosis

A
  • Deranged
  • Several
45
Q

Lung cancer causes: (3)

A
  • Smoking 72%
  • Workplace exposure 13%
  • Air pollution 8%
46
Q

Lung cancer subtypes:
1.
2. (3)

A
  1. Small cell (15-20%)
  2. Non-small cell (80-85%)
    - Adenocarcinoma
    - Squamous cell
    - Large cell
47
Q

Lung cancer: symptoms
- Usual
- Red flags (3)

A
  • Usually no signs or symptoms in early stages
  • Persistent cough/chest infection/breathlessness/tiredness
  • Coughing up blood
  • Loss of appetite/unexplained weight loss
48
Q

Lung cancer: metastatic tumour effects (4)

A
  • Cervical or supraclavicular lymphadenopathy
  • Palpable liver edge
  • Bone pain or pathological fracture
  • Persistent vomiting, seizures, focal neurology, headaches, confusion
49
Q

lung cancer screening: low dose CT scan
- Detection
- Shift?
- Mortality

A
  • Increases lung cancer detection
  • With stage shift towards treatable disease
  • Reduction in lung cancer mortality
50
Q

Upper respiratory tract infections:
- Symptoms (4)
- Complications
- Signs (3)

A
  • Pain, fever, headache, stridor
  • Quinsy (peri-tonsillar abscess)
  • Raised temperature, erythema, exudate
51
Q

Lower respiratory tract:
- Symptoms (5)
- Complications (2)
- Signs (5)

A
  • Cough, wheeze, sputum, production, pleuritic chest pain
  • Empyema, pulmonary cavity
  • Raised RR and intercostal , muscle movement, wheeze, dull percussion, bronchial breathing
52
Q

Pneumonia and LRTI:
- Detection
- Difference

A
  • Pneumonia = consolidative change on radiology
  • LRTI = no consolidative change on CXR
  • Any pathogen can cause either, all about radiological change
  • LRTI and pneumonia are a spectrum of disease
53
Q

Streptococcus pneumoniae (pneumococcus):
- Prevalence
- Structure/variation

A
  • 50-60% community-acquired pneumonia
  • Gram positive coccus, surrounded by polysaccharide capsule, over 90 serotypes
54
Q

Streptococcus pneumoniae (pneumococcus)
- Variation
- Infections (7)

A
  • Over 90 serotypes,
  • Can cause multitude of infections (LRTI/pneumonia, empyema, meningitis, infective endocarditis, abscesses, otis media and externa)
55
Q

Legionella pneumophila:
- Description
- Incubation
- Transmission (4)

A
  • Atypical pneumonia
  • 2-10 days
  • Spread by breathing contaminated aerosolised water or soil: AC units, hotels/conferences, care homes, water sprinklers
56
Q

Legionella pneumophila:
- Outbreak definition
- Symptoms

A
  • 2+ cases where onset is closely linked in time and in space
  • Hyponatraemia and liver dysfunction
57
Q

Pneymocytsis pneumonia (PCP):
- Cause
- Effects
- Diagnosis

A
  • Caused by fungus
  • Associated with immunosuppression, high risk of pneumothorax
  • Diagnosis by PCR on sputum (beta glucan usually posistive)
58
Q

Tuberculosis (TB):
- Transmission
- Culture
- Relevance

A
  • Transmission by droplets
  • Very difficult to culture in the lab
  • Notifiable disease of public health importance
59
Q

TB: active infection risk factors (5)

A
  • Young children
  • Immunocompromised hosts
  • Prison contact
  • Recent contact with TB
  • Country of high incidence
60
Q

TB: latent infection risk factors (4)

A
  • Exposure at some time
  • Evidence of scars on CXR
  • Immune response to TB (memory T-cell recognition of TB)
  • Risk of reactivation in later life
61
Q

TB signs and symptoms:
P
C
L
Chest
H

A

Pale
Cachexic
Lymphadenopathy
Chest: dullness to percussion, bronchial breathing, clear
- High temperature

62
Q

Is TB vaccine-preventable:

A
  • BCG recommended at birth in areas with high incidence
  • Protects children from severe forms of TB (TB meningitis)
63
Q

stenotic valve:

A
  • Blood flows backwards through the valve (turbulent flow)
64
Q

Bacteraemia: (3)

A
  • Presence of bacteria in the blood
  • Detected by blood cultures
  • Assessment of significance
65
Q

Infective Endocarditis (IE): definition
- definition
- Clinical presentation
- Diagnosis requirements

A
  • Bacterial (or fungal) infection of a heart valve or area of endocardium
  • Either acute or sub-acute
  • Constellations of clinical signs and investigations required to make diagnosis
66
Q

IE: Epidemiology
- Prevalence
- Mortality
- Infecting organisms / pre-disposing factors

A
  • <10 per 100,000 population per year
  • 20%
  • Have changed over time, rheumatic fever was a risk factor pre-antibiotic era (75%)
67
Q

IE: Rheumatic fever

A
  • Group A Streptococcus
  • Post-infectious, autoimmune, multi-system disease
68
Q

IE: Epidemiology
Risk factors (4)
NVIE
PVIE
P-AE
NIE

A

A. Native valve infective endocarditis
B. Prosthetic valve infective endocarditis
C. PWID-associated endocarditis
D. Nosocomial infective endocarditis

69
Q

A. Native Valve Endocarditis
- C
- PDH
- U
- BC

A
  • Cardiac abnormalities
  • Poor dental hygienes: viridans streptococci
  • Urinary tract infection: Enterococcus
  • Bowel cancer: S. gallolyticus
70
Q

B. Prosthetic valve endocarditis:
- Cause
- Prevalence
- Pathogen
- Presentation

A
  • Prosthetic valve or cardiac device related
  • 1-5% of cases, within first 2 months of surgery
  • Coagulase negative staphylococci
  • Low virulence pathogens so often sub-acute
71
Q

C. IVDU-associated endocarditis
- Age
- Features
- Pathogen

A
  • Median age 30 (M>F)
  • Right sided infection more common
    tricuspid 50%; Aortic 25%; Mitral 20%
  • Staphylococcus aureus (including MRSA) predominates, can be other organisms
72
Q

D. nosocomial infective endocarditis
- Incidence
- Age
- Causes

A
  • Increasing (>10%)
  • > 60 years
  • Often underlying cardiac disease, IV lines, invasive procedures
73
Q

IE pathogenesis:
- Immune system

A
  • The immune system is unable to eradicate an organism once located on the endocardium
74
Q

IE pathogenesis: transient bacterium

A
  • Dental related
  • Procedures in non-sterile sites e.g. urethral catheterisation
  • Portals of entry for bacterium (wounds, lines)
  • Source of bacterium often not found
75
Q

IE clinical syndrome:
- Common (=/>70%)
M
P
Cm
H

A
  • Malaise (95%)
  • Pyrexia (90%)
  • Cardiac murmurs (90%)
  • Haematuria (70%)
76
Q

IE clinical syndrome:
- Uncommon (<70%)
A
CF
ON
JL
SH
RS
S
CE

A
  • Arthraglia (25%)
  • Cardiac failures (5%)
  • Oslers node’s (15%)
  • janeway lesions (5%)
  • Splinter haemorrhages (10%)
  • Roth spots (5%)
  • Splenomegaly (40%)
  • cerebral emboli (20%)

Med Yr2 (12 decks)

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