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

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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)

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Physiology

• Ventilation
• Perfusion
• Diffusion

Anatomy Inspiration/Expiration

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INSPIRATION Passive Expiration Forced Expiration

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Respiratory bronchiole Tethering

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Normal Conducting System

Alveoli

• Surface area equivalent to that of a tennis

court.

• Very thin.

Alveolar and capillary surface

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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)
• r decreased ventilation (obstructive lung

disease or infiltrative diseases).

Transportation O2

• Primarily by hemoglobulin.
• Very little dissolved in plasma.

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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

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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
• 3rd to 6th leading cause of death

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RISK BY AGE

Pathology

• Airway limitation‐inflammation
• Goblet cell hyperplasia
• Mucus plugging
• Loss of airway tethering
• Loss of airway rigidity
• Bronchospasm

Normal Airway

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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

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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

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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

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Global initiative on chronic Obstructive Lung Disease

• 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
• r 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. ___

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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

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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

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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)

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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

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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

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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

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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

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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

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Treatment Recommendations GOLD

• Group A
• Group B
• Group C
• Group D
• Group A
• Group B
• Group C
• Group D
• S‐A Beta agonist or anticholinergic
• L‐A Beta agonist or anticholinergic
• ICS + LA Beta or LA anticholinergic
• ICS + LA Beta +/or LA anticholinergic
• ALTRERNATIVE
• LA Beta or LA anticholinergic or SA Beta

with SA anticholinergic

• LA Beta with LA anticholinergic
• LA Beta + LA anticholinergic or LA Beta +

PD4 Inh or LA anticholinergic + PD4 Inh

• ICS + LA Beta + LA Antichol. Or ICS + LA Beta

+ PD4 Inh, or LA Beta + LA antichol, LA antichol + PD4 inh

Other Considerations

• Exercise
• Mucolytics
• Antidepressants

Comorbidities

• Coronary artery disease
• Osteoporosis
• Peripheral vascular disease
• Cancer
• Heart failure
• Atrial fibrilation
• Interstitial lung diseases

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Referrences

• Global Initiative for Chronic Obstructive lung Disease
• Lancet 370; 2007, p741, “International variation…”
• Lancet 378; 2011, p991, “Lifetime risk…”
• MMWR 61, 2012, p938, “COPD among adults”
• UpToDate
• Chest 130; 2006, p1096, “Role of gastroesophageal…”
• Am J Crit Care Med 180; 2009, p3, “The Natural History…”
• NEJM 365: 2011, p1184, “Changes in Forced…”
• Pulmonary Physiology in Clinical Medicine, Tisi
• Am J Respir Crit Care Med 161; 2000, p 1608, “Time course and

recovery…”

• BMJ 1; 1977, p1645, “The natural history…”
• Am J Respir Crit Care Med178; 2008, p332, “Effect of pharmacotherapy…”
• JAMA 309;2013, p2223, “Short‐term vs conventional…”