Respiratory Lecture 5 Dr Azeem Alam, MBBS BSc (Hons) Surgical AFP Guy’s and St. Thomas’ Hospital Email: admin@bitemedicine.com Website: www.bitemedicine.com Facebook: https://www.facebook.com/biteemedicine Content reviewed on 08/04/2020. Instagram: @bitemedicine 1
Learning objectives • 2 respiratory topics: Asthma in adults and Lung cancer • 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) 2 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Case 1 History A 29-year-old male presents with shortness of breath and wheezing after exercise. His symptoms have been getting progressively worse over the last year and he has been struggling to sleep at night. Observations HR 98, BP 134/82, RR 18, SpO 2 96%, Temp 37.4°C. 3 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
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Pathophysiology Definition: chronic inflammation resulting in reversible airway obstruction and hyper- reactivity 1 5 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Pathophysiology Inflammatory response is driven by T-helper type 2 (Th2-cells) 1. Bronchial inflammation • Terminal bronchioles 2. Bronchial obstruction • Increased mucous production and mucosal oedema • Bronchospasm • Smooth muscle hypertrophy 3. Bronchial hyperresponsiveness 6 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Classifications Allergic asthma (extrinsic) • Allergen • IgE-mediated type 1 hypersensitivity • Mast cell degranulation and histamine release Non-allergic asthma (intrinsic) • Irritants and other external factors • Neutrophil release 7 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Differentials Asthma COPD Alpha-1 antitrypsin Bronchiectasis deficiency Aetiology Th2-cells and IgE Macrophages Genetic Recurrent • • • • type 1 and neutrophils pulmonary hypersensitivity infections Features Wheezing, cough Smoking history Young onset Wheezing, cough • • • • and dyspnoea Dyspnoea occurs Wheezing and dyspnea • • Trigger with or without FHx of lung High-resolution • • • (allergens, wheezing disease CT: bronchial exercise) Progressive Liver dysfunction wall thickening • • Diurnal variation Irreversible • • airway obstruction 8 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
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Investigations: diagnostic Primary investigations • Fractional exhaled nitric oxide (FeNO): inflammatory cells produce nitric oxide (> 40 ppb) • Spirometry : FEV1/FVC < 70% Investigations to consider Bronchodilator reversibility: improvement of FEV1 by ≥ 12% • Peak flow rate (PEFR): variability of > 20% throughout the day • • Airway hyperreactivity testing : histamine or methacholine direct bronchial challenge • Allergy testing : for allergic asthma 10 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Investigations: exacerbation Bedside • PEFR • Moderate: 50–75% • Severe: 33–50% • Life-threatening: < 33% Bloods • FBC : leukocytosis, eosinophilia and neutrophilia may be present • Arterial blood gas : may demonstrate acidosis or respiratory failure Imaging • Chest x-ray : hyperexpanded chest, with or without focal signs 11 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
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Levels of severity Moderate Severe (any one of) Life-threatening Near-fatal (any one of) Worsening Peak flow 33-50% Clinical signs One or both of: • • symptoms RR ≥ 25 Reduced High PaCO 2 • • • Peak flow 50-75% HR ≥ 110 consciousness Mechanical • • • Unable to complete Exhaustion ventilation • • sentences in one Arrhythmia • breath Low BP • Cyanosis • Silent chest • Poor respiratory • effort Measurements Peak flow < 33% • SpO 2 < 92% • PaO 2 < 8 kPa • 'Normal’ PaCO 2 • 13 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
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Management: chronic (adult >16 years) 15
Management: exacerbation General management for all severities: Oxygen : use in life-threatening asthma or if SpO 2 <94% • Inhaled salbutamol +/- ipratropium bromide : Nebulisers are generally used for exacerbations and can be given ‘back to back’ • Corticosteroid : Oral prednisolone is given if alert, otherwise, offer IV hydrocortisone • Steroids take a few hours to work and a course of 3 days is usually sufficient • Severe or life-threatening exacerbation Intravenous bronchodilation: magnesium sulphate may be needed • Other IV bronchodilators : second-line options include IV salbutamol and aminophylline • Ventilation: if deteriorating despite the above measures • Other considerations Antibiotics: indicated if there is a suspected bacterial infection • 16 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Summary 1 – Asthma • Asthma classically presents with a history of dyspnoea, wheeze, and cough, with diurnal variability • According to NICE, FeNO and spirometry are the first-line investigations • Offer bronchodilator reversibility or PEFR as additional investigations • First-line treatment is with a SABA , followed by an ICS . A leukotriene antagonist is then added if symptoms remain poorly controlled • Acute exacerbations are generally managed with bronchodilators and steroids 17 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Case 2 History A 62-year-old male presents with a one-month history of coughing up blood. He has felt generally lethargic recently and mentions that his clothes are feeling loose. On examination, you note tar staining of his fingernails. Some routine bloods are taken and show the following: Hb 135 g/L (135 - 180) WCC 10.9 X 10 9 /L (4.0-11.0) Na 126 mmol/L (135-145) K 4.5 mmol/L (3.5-5.5) Creatinine 70 μmol/L (55-120) 18 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
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Aetiology Majority of lung cancers are primary bronchial carcinomas . Risk factors Smoking (85% of lung cancer cases) • Family history • Asbestos exposure • Pollution • Radon exposure • Idiopathic pulmonary fibrosis • 20 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Classifications Small-cell lung cancers (SCLCs) 15% of lung cancers • Derived from neuroendocrine Kulchitsky cells • Rapid growth and patients present in an advanced stage • Non-small cell lung cancers (NSCLCs) 85% of lung cancers • Squamous cell, adenocarcinoma, large-cell, carcinoid tumours and bronchoalveolar • cells 21 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
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Pathophysiology SCLC NSCLC Small cell Squamous-cell Adenocarcinoma Large-cell (10-15%) (25-30%) (40%) (10-15%) Location Central lesion Central lesion Peripheral lesion Peripheral lesion Smoking Strong link Strong link Lower link Strong link Paraneoplastic SIADH Hypertrophic Hypertrophic Hypertrophic • • • • syndrome pulmonary pulmonary pulmonary Cushing’s osteoarthropathy osteoarthropathy osteoarthropathy • syndrome PTHrP: Ectopic βHCG • • Lambert-Eaton hypercalcaemia secretion • syndrome Cerebellar • syndrome 24 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Cancer referral pathway Cancer referral (within 2 weeks) if: CXR findings suggestive of lung cancer or • > 40 years old and have unexplained haemoptysis • Urgent CXR (within 2 weeks) if: > 40 years old and 2 of the following or PMHx of smoking and 1 of the following: • Fatigue • Cough • SOB • Chest pain • Weight loss • 25 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Investigations Bloods: not diagnostic but may reveal evidence of paraneoplastic syndromes • U&Es: hyponatraemia in SIADH • Bone profile: hypercalcaemia Imaging • CXR: coin lesion • CT chest: if CXR is abnormal, conduct CT chest and image the abdomen for staging • PET-CT: staging Special tests • Biopsy: either percutaneous if peripheral, or EBUS if central • Mediastinoscopy: assess for mediastinal lymphadenopathy as CT not always sensitive • Spirometry: assess fitness prior to surgery. FEV1 < 2L is a contraindication for pneumonectomy 26 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Investigations 27 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
Investigations 2 28 www.bitemedicine.com Instagram: @bitemedicine Facebook: /biteemedicine
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