COPD Physiology The lungs are filters Filter in oxygen Filter out - PDF document

11/4/2014 Stan Kellar, MD Chief of Clinical Affairs, BH NLR Pulmonary Medicine Sleep Medicine COPD Physiology • The lungs are filters • Filter in oxygen • Filter out carbon dioxide • (Vascular filter, not part of this discussion) 1

11/4/2014 Physiology • Ventilation • Perfusion • Diffusion Anatomy Inspiration/Expiration 2

11/4/2014 INSPIRATION Passive Expiration Forced Expiration 3

11/4/2014 Respiratory bronchiole Tethering 4

11/4/2014 Normal Conducting System Alveoli • Surface area equivalent to that of a tennis court. • Very thin. Alveolar and capillary surface 5

11/4/2014 Perfusion • Low pressure bed, PA pressure 30/10. • Approximately 6 billion capillaries in human lung, or about 2000 per alveolus. • Under normal (resting) conditions there is little or no flow to the apices, a waterfall effect. Ventilation/Perfusion • Under normal circumstances the V/Q (ventilation to perfusion) ratio is 1. • This is altered with decreased perfusion (PE) or decreased ventilation (obstructive lung disease or infiltrative diseases). Transportation O2 • Primarily by hemoglobulin. • Very little dissolved in plasma. 6

11/4/2014 Transportation of CO2 • 10% dissolved in plasma. • 20 % carried by Hemoglobin. • 70% in form of bicarbonate. • CO2 dissociation curve linear. COPD • Chronic airflow limitation • Airway inflammation • Affects more than 6% of the population • Third leading cause of death in US • Preventable • Treatable COPD • Chronic bronchitis ‐ chronic productive cough for three months in two successive years • Emphysema ‐ permanent enlargement of airspaces distal to the terminal bronchioles, loss of alveolar walls • “Asthma” ‐ Reversible airflow limitation 7

11/4/2014 Emphysema Causes • Smoking ‐ Duration and Amount. PACK YEARS • Threshold? About 25 pack years • Smoking • Smoking • Biomass fuel in developing countries Incidence • Overall 6.3% USA • Higher in men, lower education level and socioeconomic groups • Incidence increases with increasing age • 3 rd to 6 th leading cause of death 8

11/4/2014 RISK BY AGE Pathology • Airway limitation ‐ inflammation • Goblet cell hyperplasia • Mucus plugging • Loss of airway tethering • Loss of airway rigidity • Bronchospasm Normal Airway 9

11/4/2014 Airway narrowing Symptoms • Shortness of breath • Cough, with or without sputum • Wheezing • Chest tightness Dyspnea • Lung disease • Heart disease • Circulatory problems • Neuromuscular diseases • Therefore not all dyspnea is due to lung diseases 10

11/4/2014 Wild Cards • ACID REFLUX • 25% of patients with significant reflux have no reflux symptoms • Another 25% underestimate the degree of reflux • Patients with symptoms have 2x rate of exacerbations • Deconditioning Physical Findings • Wheezing • Decreased breath sounds • Crackles in bases • Diminished heart sounds • Barrel ‐ shaped chest • Tobacco stained finger tips • Clubbing is rare Chest X ‐ ray • Normal • Hyperinflation • Bullae • Flattened hemi ‐ diaphragms • Basilar scarring • Unexpected disease ‐ pneumothorax, lung cancer 11

11/4/2014 Hyperinflation Pneumothorax Spirometry • FEV1 ‐ effort dependent • FVC ‐ effort and time dependent, more than 6 seconds • FEV1/FVC ratio ‐ less than 70% • Peak flow ‐ useful for trends, very effort dependent 12

11/4/2014 G lobal initiative on chronic O bstructive L ung D isease • GOLD 1: Mild (FEV1 >80% Pred.) • GOLD 2: Moderate (FEV1 50 ‐ 80% Pred.) • GOLD 3: Severe (FEV1 30 ‐ 50% Pred.) • GOLD 4: Very severe (FEV1 < 30% Pred.) COPD Assessment Test OK < 10 Modified Medical Research Council Guide • Please Check Line That Applies to You Grade 0: I only get short of breath with strenuous exercise. ___ • Grade 1: Short of breath hurrying or up slight incline. ___ • Grade 2: I walk slower on level ground as similar aged individuals • or I stop to rest when walking on my own. ___ • Grade 3: I stop for breath when walking 100 meters or after a • few minutes. ___ • Grade 4: I am too breathless to leave the house or I am • breathless dressing or undressing. ___ • 13

11/4/2014 RISK • Related to history of exacerbations • Group A: Low risk, less symptoms ‐ GOLD 1 ‐ 2 and 0 ‐ 1 exacerbations • Group B: Low risk, More symptoms – GOLD 1 ‐ 2 and 0 ‐ 1 exacerbations • Group C: High risk, Less symptoms – GOLD 3 ‐ 4 and > 2 exacerbations • Group D: High risk, More symptoms ‐ GOLD 3 ‐ 4 and > 2 exacerbations Exacerbations • Increased dyspnea • Increased cough • Sputum production • +/ ‐ fever • +/ ‐ chest pain – chest tightness Exacerbation Treatment • Steroids, oral or IV • Antibiotics, oral or IV • Additional bronchodialators • Hospitalization • Non ‐ invasive ventilation • Ventilation • Over 7% do not return to baseline 14

11/4/2014 Smoking Cessation • Without help/nicotine replacement ‐ 10% • With help/nicotine replacement ‐ 50 ‐ 60% • ASK – ADVISE – ASSESS – ASSIST ‐ ARRANGE • Chantix • Nicotine, Give enough • Too much nicotine causes nausea Decreased airflow + smoking • Progressive lung disease • 25 times normal risk for heart attack or stroke • 8 times risk for lung, laryngeal, esophageal, stomach, kidney, bladder, oral and pancreatic cancer • Cessation rapidly reduces the risk of cardiovascular complications 15

11/4/2014 Medications: Short acting Rescue • Beta agonists, MDI or nebulizer (albuterol) • Techniques • Spacers • Cost • Intended for rescue • Primary side effects cardiac arrhythmia (tachycardia) and tremor Medications: Short acting Rescue • Anticholinergics, MDI or nebulizer (Atrovent) • Short acting • Rescue • Costs • Adverse effects rare, dryness Medications: Long acting • Beta agonists, MDI and nebulizer • Foradil and Serevent are the primary single agents with MDI • Perforomist and Brovana are the nebulized forms • Almost never used alone • Increased risk of death in asthma patients when use alone (Black Box Warning) 16

11/4/2014 Medications: Long acting • Anticholinergics, MDI • Spiriva and Tudorza • Cost Medications: Inhaled Steroids • MDI and nebulizer • Controversy • Single agents, Flovent, Asmanex, Qvar, Pulmicort • Anti ‐ inflammatory • Adverse effects ‐ oral thrush, hoarseness, possible osteoporosis, increased risk of pneumonia Medications: Steroids/Beta agonists • MDIs • Advair Discus and MDI • Symbicort • Dulera • Breo, new, fluticasone and vilanterol 17

11/4/2014 Medication: LABA + LA Anticholinergic • Anoro, new Medications: Steroids • Anti ‐ inflammatory • Oral prednisone or Medrol • Dose and length of treatment controversial • IV for hospitalized patients, dose and length of treatment controversial • Adverse effects – Hyperglycemia, thrush, increased risk of infection, osteoporosis, weight gain, myopathy Medications: Phosphodiesterase ‐ 4 Inhibitors • Daliresp – anti ‐ inflammatory • Frequent side effects with nausea, vomiting, diarrhea, generalized aches, loss of appetite 18

11/4/2014 Medication: Theophyllins • Moderate bronchodialator • Toxicity is dose related • Adverse effects – nausea, vomiting, headaches, seizures • Blood levels altered by other medications, both up and down Special Consideration • Alpha ‐ 1 Antrypsin Deficiency • Earlier emphysema with a basilar predominance • Replacement available • Testing is free Vaccinations • Yearly flu immunization • Pneumococcal vaccine for patients 65 years and older 19

11/4/2014 Oxygen • Improve mortality • Improve dyspnea • Improve quality of life • Improve cognition • Cost – over $500/mo., 1 million patients in USA at a cost of over 2 billion dollars Oxygen • PaO2 , 55 mmHg or saturation, 89% at rest • PaO2 , 60 with cor pulmonale, right heart failure or HCT > 55 • O2 saturation less than 89 % for more than 5 minutes with sleep (Look for OSA) • Pao2 < 55 or saturation <88 with exercise • In COPD patients check ABGs on O2 to check PaCO2 ANN Internal Med 1980; 93:391 20

11/4/2014 Lancett 11981; 1:681 Oxygen • No benefit for saturations > 92% • Increase in PaCO2 (Hypoventilation) • Absorptive atelectasis • Hyper ‐ oxemia can result in decreased free water clearance • Facial burns especially in patients with facial hair • Fall risk with the tubing • NO SMOKING RISK • Related to history of exacerbations • Group A: Low risk, less symptoms ‐ GOLD 1 ‐ 2 and 0 ‐ 1 exacerbations • Group B: Low risk, More symptoms – GOLD 1 ‐ 2 and 0 ‐ 1 exacerbations • Group C: High risk, Less symptoms – GOLD 3 ‐ 4 and > 2 exacerbations • Group D: High risk, More symptoms ‐ GOLD 3 ‐ 4 and > 2 exacerbations 21