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Aviation Medicine and Respiratory Disease Diploma in Aviation Medicine Course No 44. Wg Cdr Gary Davies RAF Consultant Advisor in Respiratory Medicine Consultant Respiratory Physician, Chelsea & Westminster Hospital. Introduction.
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Aviation Medicine and Respiratory DiseaseDiploma in Aviation Medicine Course No 44 Wg Cdr Gary Davies RAF Consultant Advisor in Respiratory Medicine Consultant Respiratory Physician, Chelsea & Westminster Hospital
Introduction • Commonest cause of morbidity and time off work in general population • 2nd most common medical cause of loss of flying time • Often thought to be incompatible with flying
Diseases to be covered • Asthma • Sarcoidosis • Pneumothorax • Pulmonary thrombo-embolic disease • Obstructive Sleep Apnoea • Interstitial Lung Disease • Bronchiectasis • COPD • Pulmonary Tuberculosis • Atypical Mycobacterium • Pulmonary Malignancies
Asthma - Introduction • Widespread airway obstruction of a variable nature • Variation – Spontaneous, stimulus (allergic) or treatment • Asthma and flying thought by some to be incompatible
Asthma – Natural History • Wide variety of clinical patterns • 5-10% of UK adults • Increasing prevelance • Link with childhood asthma and adult asthma • Early treatment → better prognosis
Aviation Management Problems • INDIVIDUAL • Concerns • Sudden Incapacitation • At risk individuals • Previous life-threatening attack • Variable PEF on treatment • Repeated admissions
Asthma - Symptoms • Very variable • Cough / wheeze / SOB / Nocturnal wakening / chest tightness • Look for stimuli • History very important but use OBJECTIVE assessments
Specific History • Gestation and birth weight • Recurrent respiratory or sinus infections during childhood • Whooping cough in young childhood • Persistent symptoms after the age of 5 years • Maternal smoking
Asthma - Investigation • PEF diary • Basic Spirometry • Gas transfer and RV • Reversibility testing / Steroid challenge • Exercise spirometry • Methacholine (Histamine) challenge testing • Allergy testing • Exhaled NO • Breath condensate
Treatment STEP 5 Add daily oral steroid or regular booster courses of oral steroid STEP 4 Add any or all of the following as determined by empirical trial: increase inhaled steroid up to 2000 μg/day, leukotriene receptor antagonist, theophylline, cromone STEP 3 Add long-acting β2-agonist STEP 2 Add inhaled steroid: 800 μg/day adult 400 μg/day children ******** Symbicort SMART ********* STEP 1 Inhaled short-acting β2-agonist (or other bronchodilator) Adapted from draft BTS /SIGN asthma guidelines 3. BTS/SIGN draft guidelines.
Treatment worries • SABAs as regular solo treatment • Fenoterol (NZ) 1980s – increased mortality • Potential increased risk of hospitalisation or death 1 2 • Increase PEF variability and bronchial hyper-reactivity • LABAs as regular solo treatment • Salmeterol alone 3 • Potential mechanism 4 5 • Increased brain-derived neurotrophic factor (BDNF) • IL-6 • cAMP response element (CRE) 1. Bronchodilator treatment and deaths from asthma: case control study. Anderson et al. BMJ 2005;330:117. 2. Excess mortality in patients with asthma on long acting β2-agonists. Hasford & Virchow. EurResp J 2006;28:900-2 3. Salmeterol Multicenter Asthma Research Trial (SMART). Nelson et al. Chest 2006; 129:15-26 4 mechanism of adverse effects of β2-agonists in asthma. Johnston & Edwards. Thorax 2009; 64:739-741 5. Adverse effects of salmeterol in asthma: a neuronal perspective. Lommatzsch et al. Thorax 2009; 64:763-769
New Specialist Treatment • Steroid sparing agents • IV Immunoglobulin • Xolair (Omalizumab) – anti-IgE • Bronchial thermoplasty
Disposition • Pilot Recruits • Exclusion criteria • Currently on any treatment for asthma. • Any asthmatic symptoms including nocturnal cough or exercise-induced wheezing. • Regular inhaled steroids for a period > 8 weeks in the 5 years before application. • Hospital attendance, including A&E, for asthma or wheezing in the 5 years before application. • Required oral steroids for asthma within the 5 years before application. • Required admission to an intensive care unit for asthma at any time in their life. • Required a hospital admission > 24 hours for asthma or wheeze since the age of 5
Disposition • Pilot Recruits • Objective testing • Normal full pulmonary function tests • (spirometry and reversibility, lung volumes and transfer factor). • Methacholine challenge test. • > 16mg/ml • Research • Exhaled nitric oxide level. • Allergy skin prick (basic allergen panel) • house dust mite, grass, tree pollen and aspergillus • further tests may be required if the history suggests other potential allergen. • Total IgE. • Eosinophil count
Disposition • Trained Aircrew (At present) • Can continue with Restricted flying category if • Resting Lung Function, exercise testing normal on treatment • Treatment not > step 2 BTS guidelines • Dual crew aircraft • Normal bronchial hyper-responsiveness • Infrequent exacerbations
Sarcoidosis - Introduction • Multi-system granulomatous disease of unknown aetiology • More common than thought • Often incidental finding on routine medical
Sarcoidosis – Natural History • Most commonly – asymptomatic BHL • → Asymptomatic pulmonary infiltrates • Erythema Nodosum • If shadowing persists > 1 year, ↑ risk of fibrosis • Extra thoracic often more chronic and indolent
Sarcoidosis – Natural History (2) • Stage 1 – BHL only • Stage 2 – BHL + Pulmonary Infiltrates • Stage 3 – Pulmonary Infiltrates only • Stage 4 – Irreversible fibrosis • Cardiac involvement irrespective of staging
Sarcoidosis - Investigation • Bronchoscopy • BAL and Trans-bronchial biopsies • Urine and blood calcium • Biopsy of nodes • Echocardiogram • Serum ACE level
Sarcoidosis – Treatment • None • Corticosteroids (Stage 2 +) • Azathioprine • Hydroxychloroquine • Methotrexate
Aviation Management Problems • Main risk - cardiac arrhythmia • Interference with operational effectiveness • Steroid treatment
Sarcoidosis - Disposition • Pilot Training • Any History → Unfit (risk cardiac sarcoidosis) • Trained Aircrew • Grounded until fully investigated • If no cardiac involvement and asymptomatic and no treatment • As or with co-pilot initially • Upgrade to solo after 1 year • On treatment • Grounded until above • Asymptomatic pulmonary infiltrates • REFER RESPIRATORY PHYSICIAN
Pneumothorax – Natural History • Two peaks of incidence • Young adults • Old adults • Recurrence Rate • 30% after 1st • 50% after 2nd • 80% after 3rd
Pneumothorax - Investigation • CXR • Spirometry • Hi Res CT Thorax
Pneumothorax - Treatment • Aspiration / chest drain • Operative treatment • Open pleurectomy • Thoracoscopic pleurectomy • Chemical pleurodesis (NOT recommended)
Aviation Management Problems • Sudden incapacitation • Increasing with altitude
Pneumothorax – Disposition • Pilot Training • > 2 years ago or following definitive treatment specialist referral to investigate possible underlying disease • Trained Aircrew • Pleurectomy → 3 months • VATS procedure or mini-thoracotomy preferably • If no pleurectomy - Grounding 18 months minimum • Investigation
Traumatic Pneumothorax • No associated bullous lung disease • Risk of recurrence – VERY small • No further treatment required after emergency treatment
Pulmonary thrombo-embolic disease – Natural History • Variation from single life threatening event to insidious breathlessness • Causes • Short term risks • Malignancies • Clotting disorders
Pulmonary thrombo-embolic disease - Investigation • CXR • ECG • Arterial Blood Gases • CTPA • Ventilation/perfusion scan
Pulmonary thrombo-embolic disease - Treatment • LMW heparin + warfarin followed by 3 - 6 months of warfarin for first event. • Life-long warfarin for recurrent events • Thrombolysis in life-threatening events
Aviation Management Problems • Risks of sudden incapacitation • Disabling breathlessness
Pulmonary thrombo-embolic disease - Disposition • Pilot Training • Cause unknown or recurrent episodes → Disqualifying • Recognised cause → Individual -> referral • Trained Aircrew • Grounded while on warfarin • Single episode with defined cause and normal pro-coagulation screen → upgraded after treatment • Recurrent episodes / malignancy / clotting disorder → permanent grounding
Obstructive Sleep Apnoea –Natural History • Collapse of upper airway during sleep leading to apnoea • Overweight, middle aged men most commonly • Hypoxia and hypercapnia • Hypersomnolence • Increased risks of cardiac disease if untreated
OSA - Investigation • Sleep study • Epworth Sleepiness Scale
OSA - Treatment • Address aggravating factors • CPAP • Jaw advancement splint • Surgery
Aviation Management Problems • Daytime somnolence leading to increased accidents and decreased performance • Treatment negates this risk
OSA - Disposition • Pilot Training • Disquallifying • Trained Aircrew • Grounded until response to treatment assessed • Effective treatment → full flying category • Help from specialist centre
Interstitial Lung Disease – Natural History • Characterised by diffuse parenchymal lung disease distal to the terminal bronchiole. • Large number of different disorders • Progression is dependant on specific cause.
ILD - Investigation • CXR (little use) • Hi res CT scan • Refer to specialist centre
ILD - Treatment • Complex and related to cause and pattern of disease. • Mainstay treatment involving • Oral / iv steroids • Azathioprine • Cyclophosphamide • May require transplantation