CHRONIC OBSTRUCTIVE PULMONARY DISEASE
Group of heterogeneous conditions embracing chronic bronchitis, chronic bronchiolitis (small airway disease) and emphysema characterized by air flow limitation that is not fully reversible.Emphysema is defined as enlargement of the distal airways with destruction of acinus , without associated fibrosis.Chronic bronchitis is defined clinically as cough, productive of at least 2 tablespoons of sputum on most days of 3 consecutive months in 2 consecutive years in the absence of other lung disease.Patients with a)emphysema on CT scan with normal spirometry or b) symptoms of chronic bronchitis and normal spirometry do not have COPD acc to current definition.
RISK FACTORS FOR DEVELOPMENT OF COPD
Tobacco smoke-cigarette, pipe, cigar or Environmental Tobacco Smoke (ETS)
Biomass fuel fires (indoor air pollution)
Occupation-coal miners and those who work with cadmium
Outdoor and indoor air pollution
Low socioeconomic status
Low birth wt
Lung growth-insults including childhood infections or maternal smoking
Infections-recurrent infection may accelerate decline in FEV1. Persistence of adenovirus in lung tissue may alter local inflammatory response predisposing to lung damage. HIV infection associated with emphysema
Cannabis smoking (controversial)
Genetic factors-a1-antiproteinase deficiency
- Processes important in the pathogenesis of COPD include inflammation, imbalance of proteinases and antiproteinases in the lung, apoptosis and oxidative stress.
- Pathologic changes characteristic of COPD are found in the central airways, peripheral airways , lung parenchyma and pulmonary vasculature.
- Dilation and destruction of the terminal airways , structural changes in the airway wall due to inflammation, airway edema, and mucus hypersecretion contribute to the development of COPD.
Physiologic changes of the lungs characteristic of COPD include mucus hypersecretion , ciliary dysfunction, airflow limitation, pulmonary hyperinflation, alveolar gas exchange abnormalities and pulmonary vascular disease.
a. Chronic cough
b. Chronic sputum production
c. Wheezing and chest discomfort.
d. Dyspnea-worse with exercise, Activities involving significant arm work, particularly at or above shoulder level, are particularly difficult
e. persistent (+ everyday)
f. progressive increased effort to breath, air hunger, gasping, heaviness
g. Hx of exposure to risk factors-smoking
1-antitrypsin deficiency should be considered in patients with emphysema who had
a) A minimal smoking history
b) Early onset COPD
c) A family history of lung disease
d) A predominance of lower lobe emphysema
In patients with more severe disease,prolonged exhalation , use of accessory muscle of respiration, chest hyperresonance to percussion, enlarged thoracic volume and decreased breath sounds.
prolonged expiratory phase and expiratory wheezing. signs of hyperinflation include a barrel chest and enlarged lung volumes with poor diaphragmatic excursion as assessed by percussion. use of accessory muscles of respiration, sitting in the characteristic “tripod” position to facilitate the actions of the sternocleidomastoid, scalene, and intercostal muscles.
Marked tachypnea ,cyanosis and signs of increased work of breathing(paradoxical abdominal motion) may characterize a severe COPD exacerbation.
weight loss, bitemporal wasting, and diffuse loss of subcutaneous adipose tissue. poor prognostic factor in COPD.
paradoxical inward movement of the rib cage with inspiration (Hoover’s sign), the result of alteration of the vector of diaphragmatic contraction on the rib cage as a result of chronic hyperinflation.
- A baseline ABG is often recommended for assessing patients.
- ABGs detect acute and chronic hypercapnia and the development of acute respiratory acidosis may signal acute respiratory failure.
- An elevated venous HCO3 may signify presence of a chronic respiratory acidosis.
- An elevated haemoglobin may signify chronic hypoxemia.
- Chest radiographs- thoracic hyperinflation, with flattening of diaphragm and increased retrosternal/retrocardiac air spaces, and hyperlucency with diminished vascular markings. bullae may be visible. to identify alternative diagnoses such as cardiac failure, other complications of smoking such as lung cancer
Spirometry: post-bronchodilator FEV1 less than 80% of the predicted value and accompanied by FEV1/FVC < 70%
Gold Criteria for COPD Severity
Stage I-mild-FEV1/FVC <0.7 and FEV1>80% predicted
Stage II-moderate-FEV1/FVC <0.7 and 50% FEV1 <80% predicted
Stage III-severe-FEV1/FVC <0.7 and 30% FEV1 <50% predicted
Stage IV-very severe-FEV1/FVC <0.7 and FEV1 <30% predicted
FEV1 <50% predicted with respiratory failure or signs of right heart failure
When FEV1 falls to <1 L , the 5 year survival is approx 50%
Total lung capacity (TLC), functional residual capacity (FRC),and residual volume (RV) increase to supranormal values in patients with COPD indicating ling hyperinflation and air trapping.
Emphysema and many other diseases produce a reduction in the diffusing capacity of lung (DLCO)
Long term management- smoking cessation and the correction of hypoxemia with supplemental oxygen produce the greatest survival benefit.
- Inhaled bronchodilators- beta -agonists and anticholinergics are the two main classes.
- Combination therapy (beta-agonists and anticholinergics) should be used in patients that did not achieve adequate relief with one class of drugs. Use of an MDI with a spacer or reservoir is as effective as delivery of the drug with nebulizer in most patients.
- Short acting inhaled beta2-agonists are used at two to four puffs bid-qid and PRN.
- Long acting-agonists salmeterol, formeterol or arformeterol are dosed twice daily.
- Short acting inhaled anticholinergics are used at two to four puffs bid-qid and PRN.
- Long acting anticholinergics tiotropium is dosed as one inhalation once daily.
- Methylxanthines:patient not responding to inhaled bronchodilator therapy may benefit from treatment with oral methylxanthine.sustained release theophylline is dosed once or twice daily . levels should be between 6 to 12 mg/L to avoid toxicity.
- Corticosteroids: Inhaled corticosteroids reduce the frequency and severity of exacerbations; they are currently recommended in patients with severe disease(FEV1<50%) who report two or more exacerbations requiring antibiotics or oral steroids per year. The combination of ICS with long acting ?-agonists produces further improvement in breathlessness and reduces the frequency and sverity of exacerbations.
- Systemic glucocorticoids are not recommended for long term management of COPD.
Long term domiciliary oxygen therapy(LTOT) used for 15hrs/day in patients with COPD and chronic severe hypoxemia improves survival, reduces secondary polycythaemia and prevents progression of primary pulmonary hypertension.
|PRESCRIPTION OF LONG TERM OXYGEN THERAPY (LTOT) IN COPD|
|Arterial blood gases measured in clinically stable patients on optimal medical therapy on at least two occasions 3 weeks apart.
-PaO2<7.3kPa(55mm Hg) irrespective of PaCO2 and FEV1<1.5 L
-PaO2 7.3-8 kPa(55-60 mm Hg) plus pulmonary hypertension, peripheral oedema or nocturnal hypoxaemia.
-Patient stopped smoking.
Use at least 15 hrs/day at 2-4 L/min via nasal prongs to achieve a PaO2>8kPa (60 mm Hg) without unacceptable rise in PaCO2.
- Vaccinations: annual Influenza and Pneumococcal vaccinations reduce serious illness and mortality in patients with COPD.
- Intravenous -1 antitrypsin (A1AT) augmentation therapy may benefit select patients with A1AT deficiency and COPD.
- Mucolytics (e.g. acetylcysteine 200mg orally 8 hrly for 8 weeks in the first instance), antitussives, antioxidants ,antibiotics, vasodilators, respiratory stimulants have shown significant benefit.
- Chest physiotherapy
- Pulmonary rehabilitation
- Psychoactive drugs
- Surgical treatment options are
- Giant bullectomy
- Lung transplantation
- Lung volume reduction surgery
A recent study has suggested that a composite score comprising the body mass index (B),the degree of airflow obstruction (O), a measurement of dyspnea (D) and exercise capacity (E) may assist in predicting death from respiratory and other causes.
|Variable points on BODE index
0��������� 1�������������� 2�������������� 3
|FEV1��������������������������� �������?65��� 50-64����� 36-49������ ?35
Distance walked������������ ?350� 250-349� 150-249��� ?149
In 6 min(m)
MMRC dyspnea scale 0-1����� 2��������������� 3���������������� 4
Body mass index >21�� ?21
A patient with a BODE score of 0-2 has a mortality rate of around 10% at 52 months whereas a patient with� a BODE score of 7-10 has a mortality rate of around 80% at 52 months.
ACUTE EXACERBATION OF COPD
Increased breathlessness, often accompanied by cough, sputum production, wheezing, chest tightness or other symptoms and signs of acutely worsened respiratory status define a COPD exacerbation.
Infection and air pollution are the most common causes.
- Cardiac ischemia
Investigation: CXR ; ABG : Pao2<60mmhg, SpO2<90% when breathing room air- indicates respiratory failure
Moderate to severe acidosis pH<7.36 plus hypercapnia (PaCO2>50mmHg) In a pt with Respiratory failure is an indication for NIV/mechanical ventilation
Routine blood work , Oxyhemoglobin saturation
Indications for Hosp admission for AE
Marked increase in intensity of symptoms e.g. sudden development of resting dyspnea
Severe background copd
Onset of new physical signs eg cyanosis, peripheral edema
Failure of AE to respond to initial medical mgmt
Significant co morbidities
Newly occurring arrhythmias
Insufficient home support
Intensive Care Unit (ICU) admission
indications include severe dyspnea that does not adequately respond to therapy, mental status changes, and persistent or worsening hypoxemia, hypercapnia, or respiratory acidosis despite medical therapy.
Oxygen therapy -24-28% of oxygen at 2-4 l/min
Inhaled bronchodilators: short acting inhaled ?2 adrenergic agonists are the first line therapy for COPD exacerbations.
Short acting inhaled anticholinergic agents such as ipatropium bromide have similar efficacy .
Combined therapy is the most efficacious.
Antibiotics: indicated for patients with increased dyspnea, sputum volume and sputum purulence.
Haemophilus influenza, Streptococcus pneumonia and Moraxella catarrhalis are the most often causative agents.
Trimethoprim/sulfamethoxazole; amoxicillin ; azithromycin; co-amoxiclav; 2nd or 3rd generation cephalosporin are effective.
Systemic corticosteroids Prednisone 30-40 mg PO daily
For patients with severe COPD exacerbation Prednisone 60 mg PO daily or IV methylprednisolone 60 mg IV q6h.
Indications for invasive mechanical ventilation:-
Severe dyspnea with increased work of breathing, life threatening hypoxemia, respiratory acidosis, respiratory arrest, impaired mental status.
Use of inhaled bronchodilators less frequently than every 4 hrs ; clinical and ABG stability for at least 12-24hrs; acceptable ability to eat, sleep and ambulate ; adequate patient understanding of home therapy and adequate home arrangements.