Respiratory Flashcards
Define asthma
Chronic inflammatory airway disease characterised by intermittent reversible airway obstruction, bronchial hyper-responsiveness and inflammation
What is the aetiology of asthma?
Multi-gene association interacting with environmental exposure
- Initial trigger leads to the release of inflammatory mediators
- Activation and migration of other inflammatory cells.
- Th2 lymphocytic response - release of interleukins, chemokines etc.
- Inflammatory cells move to the airway, causing changes in the epithelium, airway tone, hyper-secretion of mucus, mucociliary function alteration and increased smooth muscle responsiveness.
Acute: SM contraction leading to bronchoconstriction Mucus hypersecretion Oedema Airway obstruction
Chronic:
Proliferation of SM cells and fibroblasts causing airway remodelling
What are the risk factors of asthma?
Family history Atopic history - eczema, dermatitis, allergic rhinitis Obesity GORD Nasal polyposis
Exposure to allergens/precipitants: Cats Dogs Cockroaches Dust mites Fungal spores Tobacco smoke Fumes from chemicals eg bleach Pollen from trees, weeds, and grass. Viral infections - rhinovirus, influenza Bacterial infections - Mycoplasma pneumoniae, chlamydia pneumoniae Cold Exercise Extreme emotion
Summarise the epidemiology of asthma
Affects 10% of adults and 5% of children
Prevalence is increasing
Highest hospitalisation rates and asthma deaths were amongst black patients
What are the presenting symptoms of asthma?
Cough
Wheeze
SOB/dyspnoea precipitated by allergen exposure
Chest pain/tightness
Nocturnal symptoms
Worse at night
Variation in symptoms (episodic history) - sometimes fine and sometimes symptomatic
Previous hospitalisation for asthma
What are the signs on physical examination of asthma?
Nasal polyps/congestion Polyphonic high-pitched expiratory wheeze Tachypnoea Prolonged expiratory phase Hyperinflated chest Chest may be silent in severe asthma
What are the appropriate investigations for asthma?
Forced Expiratory Volume in 1 second/Forced Vital Capacity - <80% of predicted
FEV1 <80% of expected
PEFR - variation >20% over 3 days a week over several weeks. >20% increase following bronchodilator therapy
ACUTE: Peak flow Pulse oximetry ABG CXR - to exclude other diagnoses (e.g. pneumonia, pneumothorax). Normal or hyperinflated. May show signs of infection. FBC - raised WCC if infective exacerbation CRP U&Es Blood and sputum cultures
CHRONIC:
Peak flow monitoring - often shows diurnal variation with a dip in the morning
Pulmonary function test
Bloods - Eosinophilia, IgE level, Aspergillus antibody titres
Skin prick tests - identify allergens
What is the management of an acute exacerbation of asthma?
ABCDE and necessary resuscitation
Monitor O2 sats, ABG, PEFR and U&Es (K+ lowered by bronchodilators)
High-flow oxygen (get to 94-98%)
Salbutamol nebulizer (5 mg initially continuously, then 2-4 hourly)
Nebulised Ipratropium bromide (0.5 mg QDS)
Steroid therapy: 100-200 mg IV hydrocortisone. THEN, 40 mg oral prednisolone for 5-7 days
If no improvement - IV magnesium sulphate
Consider IV aminophylline infusion
Consider IV salbutamol
May need ITU and ventilation if fatiguing.
- Normal PCO2 is a BAD SIGN as they should be hyperventilating and blowing off their CO2 (PCO2 should be low)
Treat underlying cause (e.g. antibiotics if it is an infective exacerbation)
DISCHARGE when: PEF > 75% predicted Diurnal variation < 25% Inhaler technique checked Stable on discharge medication for 24 hours Patient owns a PEF meter Patient has steroid and bronchodilator therapy Arrange follow-up
What is the management of chronic asthma?
Start on the step that matches the severity of the patient’s asthma
- Inhaled short-acting beta-2 agonist used as needed eg SALBUTAMOL
If needed > 1/day then move onto step 2 - SABA + regular inhaled low-dose steroids (400mcg/day)
- SABA + low-dose steroids + inhaled long-acting beta-2 agonist
If inadequate control with LABA, increase steroid dose (800 mcg/day)
If no response to LABA, stop LABA and increase steroid dose (800 mcg/day) - Increase inhaled steroid dose (2000 mcg/day)
Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2 agonist tablet) - Add regular oral steroids
Maintain high-dose oral steroids
Refer to specialist care
What are the possible complications of asthma?
Exacerbations Airway remodelling Oral candidiasis secondary to incorrect use of inhaled corticosteroids Growth retardation Chest wall deformity – Harrison’s sulcus Recurrent infections Pneumothorax Respiratory failure Death
What is the prognosis of asthma?
Patients with well-controlled asthma have the same life expectancy as patients without
Many children improve as they get older
Adult-onset asthma is usually chronic
Define COPD
A chronic progressive lung condition that is characterised by irreversible airflow obstruction which encompasses emphysema and chronic bronchitis.
What is emphysema and describe its aetiology?
Pathological diagnosis of permanent destructive enlargement of air spaces distal to the terminal bronchioles
Destruction and enlargement of alveoli due to elastin breakdown, causing loss of the elastic traction that keeps small airways open in expiration.
What is chronic bronchitis and describe its aetiology?
Chronic cough and sputum production on most days for at least 3 months per year over 2 consecutive years
Narrowing of the airways due to bronchiole inflammation and bronchi with mucosal oedema, mucous hypersecretion (increased goblet cell size and number) and squamous metaplasia
What are the causes/risk factors of COPD?
CIGARETTE SMOKING Advanced age White ancestry Air pollution Occupational exposure (dust, traffic fumes, sulphur dioxide) Male sex Developmentally abnormal lung Genetic disorders eg alpha-1 antitrypsin deficiency (common cause in young, non-smokers)
Summarise the epidemiology of COPD
More common in those over 65 years old
Slightly higher prevalence in men
Very common - prevalence up to 8%
What are the presenting symptoms of COPD?
Chronic cough and white frothy sputum production (often in morning) Progressively worsening SOB Fatigue Wheeze Reduced exercise tolerance History of smoking
What are the signs on physical examination of COPD?
Barrel chest Hyper-resonance on auscultation Quiet breath sounds, prolonged expiration, crepitations Wheeze Coarse crackles Tachypnoea Tchycardic Asterixis Cyanosis Clubbing Use of accessory muscles Bounding pulse
In late stages, signs of right heart failure i.e. raised JVP, ankle oedema, RV heave
What are appropriate investigations for COPD?
Spirometry - FEV1/FVC <0.7
Pulse oximetry - low O2 sats (88-90%)
CXR - hyperinflation (>6 anterior ribs visible, flat hemidiaphragms)
ECG - risk factors for COPD similar to those of IHD
Alpha-1 antitrypsin
Acute presentation:
ABG - PaCO2 >50mmHg +/- PaO2 <60mmHg suggests respiratory insufficiency
FBC - increased WCC and haematocrit, raised Hb (secondary polycythaemia)
Sputum culture
What is the management of an acute exacerbation of COPD?
Short acting bronchodilator
Systemic corticosteroid which is transferred to inhaled corticosteroid
Airway clearance techniques (respiratory physio to clear sputum)
Supplementary O2 - 24% via non-variable flow Venturi Mask (aim for 88-92% O2 sats)
Antibiotics if infectious exacerbation
Non-invasive positive pressure ventilation if respiratory insufficiency (BiPAP)
Prevent infective exacerbations: pneumococcal & influenza vaccination
What is the management of COPD?
Short or long-acting bronchodilator (SABA or LABA, anti-cholinergics eg ipratropium bromide via inhaler or nebs)
If LABAs used >2 exacerbations per year - use steroids (oral eg prednisolone or inhaled eg budesonide)
Patient education and prophylactic vaccination
Smoking cessation
Pulmonary rehabilitation
Long term O2 therapy
What are possible complications of COPD?
Cor pulmonale - R sided heart failure secondary to long-standing COPD (chronic hypoxia - pulmonary vasoconstriction - pulmonary hypertension) Recurrent pneumonia Pneumothorax Respiratory failure Anaemia Secondary polycythaemia
What is the prognosis of COPD?
Variable prognosis dependent on genetic predisposition, environmental exposure, comorbidities
High level of morbidity
Three-year survival rate 90% if <60 years old, FEV1>50% predicted
Three-year survival rate 75% if >60 years old and FEV1 40-49% predicted.
Define acute respiratory distress syndrome
Syndrome of acute and persistent lung inflammation with increased vascular permeability due to non-cardiogenic pulmonary oedema.
What are the four characteristics of Acute Respiratory Distress syndrome?
- Symptoms occur within 1 weeks of insult
- CXR shows diffuse bilateral opacities
- Pulmonary oedema cannot be explained by heart failure (no clinical evidence for increased left atrial pressure so PCWP <18mmHg)
- PaO2:FiO2 < 300mmHg (hypoxaemia regardless of level of positive-end expiratory pressure)
Summarise the aetiology of acute respiratory distress syndrome
Systemic inflammation causes cytokines secretion leading to damage to alveolar or capillary endothelium.
Increases permeability of membrane, leading to fluid moving into alveoli - PULMONARY OEDEMA.
Fluid prevents normal gas exchange and surfactant is diluted leading to eventual alveolar collapse - DECREASED LUNG COMPLIANCE.
What are risk factors for acute respiratory distress syndrome?
Sepsis - pneumonia, UTI, infected intravenous line Acute pancreatitis Burns injury Trauma Near drowning DIC Toxic smoke inhalation Aspiration of gastric contents Transfusion Drug overdose/reaction Transplantation
Summarise the epidemiology of acute respiratory distress syndrome
Annual UK incidence ~ 1 in 6000
Critical illness, cigarette smoking and alcohol use are predisposing factors.
Most common cause is sepsis
What are the presenting symptoms of acute respiratory distress syndrome?
Severe shortness of breath Rapidly worsening respiratory failure Cough Respiratory distress Dyspnoea
What are the signs on physical examination of acute respiratory distress syndrome?
Cyanosis Tachypnoea Hypoxaemia Diffuse crackles on auscultation - widespread inspiratory crepitations Tachycardia Signs are BILATERAL
What are the appropriate investigations for acute respiratory distress syndrome?
CXR - will show bilateral opacities if ARDS
ABG - low PaO2 - HYPOXAEMIA
Investigations to determine cause:
Sputum culture - positive for infectious agent if sepsis is cause
Blood culture - test for any underlying infection causing sepsis
Urine culture - test for any underlying infection eg UTI causing sepsis
Amylase and lipase - raised if acute pancreatitis is underlying cause
Bloods - FBC, U&E, LFT, ESR/CRP, clotting
Investigations to rule out cardiogenic pulmonary oedema:
Serum BNP - raised if due to heart failure
Echo - if due to heart failure would show decreased ejection fraction or abnormal relaxation of myocardium
Pulmonary artery catheterization: PCWP <18 mmHg (if higher suggests heart failure as cause of pulmonary oedema due to raised pulmonary BP)
Define pulmonary embolism
Occlusion of the pulmonary vasculature (usually pulmonary arteries) by a venous thromboembolus usually from the deep veins of the lower limbs.
Summarise the aetiology and risk factors of pulmonary embolism
VIRCHOW’S TRIAD
A venous thromboembolus travels through the circulation to the pulmonary vasculature where it causes an occlusion
Usually from a DVT in the lower limb.
Most PEs originate from the veins above the knee
Rarely from right atrium in patients with AF
Other embolising agents: amniotic fluid, air, fat, tumour, septic emboli (from Right Sided Endocarditis)
Risk factors: Bed ridden >3 days Recent surgery <12 weeks Recent long haul flight or care journey Sedentary lifestyle OCP Genetic coagulation disorders - factor V leiden, protein C deficiency Trauma Pregnancy Obesity Active cancer Smoking Varicose veins Previous or FHx of DVT or thromboembolic event
Summarise the epidemiology of pulmonary embolism
Relatively common especially in hospitalised patients
Occur in 10-20% of people with confirmed proximal DVT
What are the presenting symptoms of pulmonary embolism?
Small PE - asymptomatic
Sudden onset, severe, PLEURITIC chest pain Chest pain better on leaning forwards Dyspnoea Cough Haemoptysis Fatigue Fever Feeling of apprehension
Large (or proximal): Shock Syncope Acute right heart failure Sudden death
Symptoms of DVT:
Unilateral, painful, erythematous swelling of leg
What are the signs on physical examination of pulmonary embolism?
Small: often no clinical signs, however, the earliest signs are tachycardia and tachypnoea
Moderate: Tachypnoea Tachycardia Pleural Rub Hypoxaemia
Massive PE:
Shock (increased HR and RR, decreased BP)
Cyanosis
Signs of Right Heart Strain (increased JVP, Left parasternal heave, accentuated S2 heart sound)
Multiple small recurrent:
Signs of pulmonary HTN and right heart failure
What are the appropriate investigations for a pulmonary embolism?
Wells Score: should be calculated in patients with suspected PE
CTPA - direct visualisation of of thrombus in pulmonary artery - DIAGNOSTIC!!
Ventilation-Perfusion (V/Q) Scan - area is ventilated but NOT perfused. If negative, excludes PE
D-dimer - elevated
ECG - sinus tachycardia, right axis deviation, RBB
CXR: often normal, but done to exclude other DDx
Echo: may show right heart strain
Doppler USS Lower Limbs: to examine for venous thrombosis
ABG - respiratory alkalosis
What is the management of a pulmonary embolism?
DVT prevention:
Compression stockings
Regular calf exercises in periods of immobility
Heparin prophylaxis i.e. pre-surgery
Early mobilisation and hydration post-surgery
Prevention of further PE:
Anticoagulation eg warfarin, heparin
Surgically place filter in IVC
If Haemodynamically stable:
Respiratory Support: Supplemental high concentration O2 (Target saturations 94-8%)
Anticoagulation with heparin or LMW heparin
Change to oral warfarin therapy (INR 2-3) for a minimum of 3 months
Analgesia
If Haemodynamically Unstable: Resuscitate: give O2 and IV fluid Thrombolysis i.e. Alteplase Vasoactive agents for Hypotension i.e. noradrenaline Anticoagulation i.e. LMWH
Thrombectomy if needed
What are the possible complications of pulmonary embolism?
Sudden cardiac death Cardiac arrest Right heart failure Pulmonary hypertension Recurrent venous thromboembolism Pulmonary infarction
