respiratory

RespiratoryLecture 6

Dr Azeem Alam, MBBS BSc (Hons)Surgical AFPGuy’s and St. Thomas’ Hospital

Email: [email protected]: www.bitemedicine.comFacebook: https://www.facebook.com/biteemedicineInstagram: @bitemedicine Content reviewed on 11/04/2020.

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Learning objectives• 2 respiratory topics: COPD and Pneumonia

• Case-based discussion(s) to identify the top differentials and why

• Theory to cover pathophysiology, diagnostic criteria, investigations and

management

• Quiz (Mentimeter and multi-step SBAs)

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Case 1

History

A 57-year-old male presents with a 4-month history of a productive cough and shortness of breath at rest. He has a 20-pack-year smoking history.

The diameter of the chest is increased on examination, with some wheezing on auscultation.

Observations

HR 94, BP 128/84, RR 20, SpO2 93%, Temp 37.6°C.



PathophysiologyDefinition: progressive airflow limitation that is irreversible. Characterised by emphysema and chronic bronchitis.

Inflammation• Inhaled stimuli causes the activation of macrophages and neutrophils

Risk factors• Smoking• Alpha-1 antitrypsin deficiency• Air pollution


Pathophysiology


PathophysiologyPhysiological outcome• Remodelling and narrowing of airways• Increased airway resistance• Enlargement of mucus-secreting glands • Hypoxia and vascular bed changes result in pulmonary hypertension (cor pulmonale)

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Clinical featuresSymptoms SignsShortness of breath: initially exercise-induced, eventually at rest

Tar staining

Productive cough Tachypnoea

Fatigue Barrel chest Hyperresonance on percussionWheeze and quiet breath soundsExacerbation• Coarse crepitations• Pyrexia• Asterixis


DifferentialsCOPD Asthma Bronchiectasis

• Smoking • Alpha-1 antitrypsin

deficiency

• Allergen • Pollution• Exercise

• Associated with cystic fibrosis

• Recurrent infections

• Later in life • Irreversible

• Early in life • Atopy• Family history • Diurnal variation• Reversible

• Bronchial dilation• Significant purulent

sputum


Suspected casesNICE recommend investigating for suspected COPD in people over 35 years old, with a risk factor (currently smoking or ex-smoker) and 1 or more of the following:

• Exertional breathlessness• Chronic cough• Regular sputum production• Winter ‘bronchitis’• Wheeze


InvestigationsBedside• ECG: right sided heart failure (e.g. right axis deviation and RBBB) • Sputum: culture if evidence of exacerbation

Bloods• Inflammatory markers: if evidence of exacerbation• Arterial blood gas: possible type 2 respiratory failure

Imaging• CXR: flattened diaphragm and hyperinflation

Special tests• Spirometry: FEV1/FVC <0.70 and lack of reversibility post-bronchodilator • TLCO: perform if symptoms are disproportionate to spirometry results


Investigations

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ManagementThe GOLD classification is widely used, more so than NICE, in guiding the management of COPD [2]. GOLD classify airway obstruction as follows:

Severity of airflow obstruction Post-bronchodilator FEV1/FVC FEV1% predicted

Stage 1: Mild <0.70 ≥80%

Stage 2: Moderate <0.70 50-79%

Stage 3: Severe <0.70 30-49%

Stage 4: Very severe <0.70 <30%


Management• Smoking cessation advice should be offered to all• Vaccinations: one-off pneumococcal and annual influenza • Inhaler therapy: all patients will be started on a short-acting bronchodilator PRN and

may have additional long-acting agents


Management: initial therapyExacerbations Symptoms

between exacerbations

Inhaler

GOLD A ≤ 1 per year notrequiring admission

Mild Any bronchodilator (short or long acting)

GOLD B Severe LABA or LAMA

GOLD C ≥ 2 per year or 1 requiring admission

Mild LAMA

GOLD D Severe • LAMA or• LAMA + LABA or• ICS + LABA

Mild symptoms(MRC ≤ 1 OR CAT <10)

Severe symptoms(MRC ≥ 2 OR CAT ≥ 10)


Long-term oxygen therapy• Long term oxygen therapy (LTOT): supplemental O2 for at least 15 hours per day. ABG

measured on 2 separate occasions

• Indicated if a non-smoker and:• PaO2 <7.3 kPa

or• PaO2 ≥7.3 and <8 kPa and 1 of the following:

• Secondary polycythaemia• Peripheral oedema• Pulmonary hypertension


Management: exacerbationManagement is guided by observations, ABG, inflammatory markers, and CXR.

• Controlled oxygen: aim SpO2 88-92% if hypercapnic on ABG, otherwise aim for 94-98%

• Nebulised bronchodilators: salbutamol and ipratropium bromide

• Corticosteroids: usually a 5-day course

• Antibiotics: empirical antibiotics such as amoxicillin and doxycycline

• Theophylline: consider if there is an inadequate response to nebulisers

• Ventilation: if evidence of worsening respiratory acidosis• Non-invasive ventilation: BiPAP• Mechanical ventilation if BiPAP fails


Summary: COPD• COPD is a progressive, irreversible airflow obstruction due to chronic bronchitis and

emphysema

• Risk factors include smoking, occupational exposure (dust, chemicals, gases, coal), and genetic causes (alpha-1-antitrypsin deficiency)

• COPD can be distinguished from asthma with a lack of reversibility post bronchodilator

• GOLD criteria for management is dependent on frequency and severity of the exacerbations

• One-off pneumococcal vaccine and an annual influenza vaccine


Distinction question


A1AT genotypes

Disease GenotypeNormal PiMMModerate deficiency PiSSSevere deficiency PiZZ

Case 2

History A 64-year-old female presents to the emergency department with shortness of breath and a productive cough.

She has a history of hypertension, for which she takes amlodipine.

Observations

HR 100, BP 120/80, RR 20, SpO2 94%, Temp 38.2 °C.


Pathophysiology

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AetiologyCategorised into:• Community-acquired pneumonia (CAP)• Hospital-acquired pneumonia (HAP) • Atypical pneumonia• Aspiration pneumonia


AetiologyCategory Organism Clinical feature

Community-acquired pneumonia

Streptococcus pneumoniae • The most common cause of pneumonia

Haemophilus influenzae • Associated with COPD

Staphylococcus aureus • Post viral URTI (commonly)

• Abscess and empyema

Hospital-acquired pneumonia• Occurs ≥ 48 hours after

admission to hospital

Gram-negative bacteria and staphylococcus aureus

• May require broad-spectrum antibiotics


AetiologyCategory Organism Clinical feature

Atypical pneumonia• Difficult to gram stain and

culture • Interstitial inflammation• Atypical presentation• CXR: no consolidation

Mycoplasma pneumoniae • Young adults • Autoimmune haemolytic

anaemia and erythema multiforme

Legionella pneumophila • Water source exposure• Hyponatraemia• Deranged LFTs

Chlamydia psittaci • Exposure to birds

Aspiration pneumonia• Inhalation of oropharyngeal

contents • Commonly right lower lobe

Klebsiella pneumoniae, anaerobes, streptococcus pneumoniae, staphylococcus aureus, haemophilus influenzae

• Redcurrant jelly sputum • Upper lobe abscess• Alcoholics and diabetics• Poor swallow


Clinical features

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InvestigationsBedside• Sputum culture: allows assessment of organism and antibiotic sensitivities

Bloods• FBC: leukocytosis• U&Es: deranged renal function and elevated urea in severe disease• CRP: raised• Arterial blood gas: perform if hypoxic to assess for respiratory failure

Imaging• CXR: consolidation is the classic finding, but may be absent with atypical pneumonia

Investigations to consider:• Urinary antigen testing: useful to determine if the cause is pneumococcal

pneumonia or legionella• Serology: can identify mycoplasma infection


Investigations

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CURB-65Estimate mortality with CAP to determine inpatient vs. outpatient treatment• Low-risk (0-1): community-based care• Intermediate-risk (2): hospital-based care• High-risk (≥ 3): consider ITU assessment

CURB-65

Criteria Marker (1 point for each marker)

Confusion Abbreviated Mental Test Score ≤ 8, or new disorientation in person, place or time

Urea > 7mmol/L

Respiratory rate ≥ 30/min

Blood pressure SBP < 90mmHg or DBP < 60mmHg

65 ≥ 65 years of age


Management: CAP

Category Antibiotic(s)Low severity (CURB ≤ 1) Amoxicillin

Penicillin-allergic or atypical: offer doxycycline or clarithromycin

Moderate severity (CURB 2) Oral amoxicillin and add clarithromycin if atypical

High severity (CURB ≥ 3) IV co-amoxiclav and clarithromycin


Management: HAP

Category Antibiotic(s)Low severity Oral co-amoxiclav

Penicillin-allergic: doxycycline or levofloxacin

High severity Broad-spectrum: such as IV tazocin or ceftriaxone

Suspected or confirmed MRSA Add IV vancomycin


Summary: Pneumonia• Pneumonia presents with a brief history of shortness of breath, pleuritic chest pain,

productive cough, and fever

• Atypical pneumonia can cause ‘atypical’ symptoms with a normal CXR

• Categorised into CAP, HAP, atypical and aspiration pneumonia

• Streptococcus pneumoniae is the most common bacterial cause

• CURB-65 is used to risk-stratify patients with CAP, with a score of ≥ 2 warranting admission

• Management is with antibiotics as per local guidelines and tailored to sensitivities


Distinction question

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References1) National Heart Lung and Blood Institute / Public domain.

https://upload.wikimedia.org/wikipedia/commons/3/37/Copd_2010Side.JPG2) James Heilman, MD / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0).

https://upload.wikimedia.org/wikipedia/commons/0/0b/COPD.JPG3) See page for author / Public domain.

https://upload.wikimedia.org/wikipedia/commons/f/fb/New_Pneumonia_cartoon.jpg4) Häggström, Mikael (2014). Medical gallery of Mikael Häggström 2014.

https://upload.wikimedia.org/wikipedia/commons/2/20/Symptoms_of_pneumonia.svg5) Mikael Häggström, M.D. - Author info - Reusing imagesWritten informed consent was obtained

from the individual, including online publication. / CC0. https://upload.wikimedia.org/wikipedia/commons/5/51/X-ray_of_lobar_pneumonia.jpg

44Buy our textbook at www.bitemedicine.com

https://upload.wikimedia.org/wikipedia/commons/3/37/Copd_2010Side.JPG

https://creativecommons.org/licenses/by-sa/3.0

https://upload.wikimedia.org/wikipedia/commons/0/0b/COPD.JPG

https://upload.wikimedia.org/wikipedia/commons/f/fb/New_Pneumonia_cartoon.jpg

https://upload.wikimedia.org/wikipedia/commons/2/20/Symptoms_of_pneumonia.svg

https://upload.wikimedia.org/wikipedia/commons/5/51/X-ray_of_lobar_pneumonia.jpg

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