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· Emphysema is characterized by an increase in the sizes of the airspaces distal to the terminal non-respiratory bronchiole. This increase in size beyond normal arises from the destruction of the airspace walls.
· There is considerable overlap in both etiology and symptomatology among patients with emphysema, asthma, and chronic bronchitis
· About 2/3 of adults in the U.S. will have emphysematous changes at autopsy, and up to 10% of these will have had severe clinical disease
· Roughly 3-5% of the U.S. population suffers from asthma
· About 10% of cigarette smokers have significant chronic airflow obstruction associated with chronic bronchitis
· The current hypothesis postulates that enzymatic mechanisms of tissue destruction (protease pathogenesis hypothesis) are due to an excess of proteolytic enzymes (elastase)
· Major source of elastase are PMNs and alveolar macrophages
· Alpha -1 protease inhibitor (alpha-1 anti-trypsin) is the major antiprotease in the lower respiratory tract
· Cigarette smoke caues an oxidative inactivation of alpha-1 anti-trypsin
· There may also be decreased elastin resynthesis destruction of lung tissue
· Alpha-1 antiprotease (anti-trypsin) is a plasma protease inhibitor synthesized in the liver which inhibits PMN elastase
· Antiprotease deficiency is associated with a 20-30x increased risk of pulmonary disease
· The deficiency occurs in 1-2% of those with emphysema
· The PiZ phenotype (autosomal recessive) results in a severe deficiency of the enzyme
A. Anatomic Classification:
· There are four types, categorized by the manner in which the acinus is involved:
1) Proximal acinar emphysema (centrilobular) - associated with cigarette smoking and distal airway inflammation; localized in upper lung zone and causes symptomatic chronic airflow obstruction
· Panacinar (panlobular) - involves the entire acinus uniformly; associated with the antiprotease deficiencies, worse in lower zones of the lung
· Distal acinar (paraseptal) - involves the distal acinus, ducts, and alveolar sacs; causes fibrosis, associated with pneumothorax/bullous disease and usually occurs in a subpleural location
· Irregular - affects the acinus in an irregular manner; associated with scarring and fibrosis
B. Clinical Classification
· Divides emphysema into three types according to clinical presentation:
1) Compensatory emphysema - no acinar destruction; includes infantile lobar emphysema, localized emphysema with infection, bronchial tumor or aspirated FB, and compensatory changes after pulmonary resection
2) Diffuse obstructive emphysema - major component of COPD; two forms based on sputum production
· Type A (dry) = cough, dyspnea, barrel chest, CXR with overinflation, flat diaphragms, no fibrosis, decreased pulmonary vasculature, pan-acinar type destruction, good prognosis
· Type B (wet) = severe cough, copious sputum production, rales, wheezing, cyanosis, CXR with moderate hyperinflation, fibrosis in lower lobes, increase in central pulmonary vascularity, centrilobular destruction, poor prognosis
3) Bullous emphysema - congenital cysts and blebs, which can be single, multiple, or coalesce; may fill with fluid or become infection
· Bleb = intrapleural airspace separated from alveoli by a thin pleural covering
· Bulla = subpleural airspace that results from the destruction of pulmonary tissue
· Both types are thin walled air sacs under tension that can cause compression and atelectasis of normal pulmonary tissue
· There is no single test which will identify those patients most likely to benefit from surgery
· Compare symptoms of bullae to symptoms of underlying pulmonary disease
· Dyspnea is the most common symptom of bullous disease, and its presence alone implies a good surgical result
· Chronic cough, however, is an indicator of poor surgical outcome
· Remove as little functioning pulmonary tissue as possible
· Trim away the thin wall of large bullae and ligate the base
· Obliterate smaller bullae and place multiple chest tubes
· Common complications inclue prolonged air leaks and residual pneumothorax
· Mortality rate is about 10-20% and is related to the severity of underlying disease
· Median sternotomy may result in less morbidity for patients with bilateral disease
· Accumulation of gas within the pleural space. A pneumothorax that has no known etiology or underlying disease is called a primary spontaneous pneumothorax. When there is an underlying disease process, this results in a secondary spontaneous pneumothorax. Other types of spontaneous pneumothorax include catamenial and neonatal. Traumatic, iatrogenic, and diagnostic pneumothorax are also encountered.
· Occurs typically in young adults; the incidence is 9 per 100,000
· The usual patient is a tall, thin male, aged 25 to 30, who smokes and has a family history of pneumothorax
· If the patient has had a pneumothorax before, there is a 90% chance it is on the same side
· Simultaneous bilateral pneumothorax occurs in about 10% of cases
· A ruptured bleb is the cause, and about 15% are seen on CXR
· This type of pneumothorax recurs with increasing frequency: 50% after first episode, 60% after second episode, 80% after third episode
· In 20% of patients with spontaneous pneumothorax, it will be related to underlying pulmonary disease
· The most common underlying disease is COPD
· Neonatal spontaneous pneumothorax is associated with hyaline membrane disease, renal malformation, Potter's syndrome, and meconium aspiration
· Catamenial spontaneous pneumothorax occurs during menstruation and does not occur during periods of non-ovulation
· Most occur during the 3rd and 4th decades and 90% are on the right side
· Pain is the most common symptom and is usually sharp or pleuritic
· Dyspnea is the next most common symptom
· Orthopnea, hemoptysis, and non-productive cough are less common
· The affected chest is hyper-resonant, tympanitic, and there are decreased breath sounds
· On chest film, subcutaneous emphysema and/or mediastinal emphysema may be present, as well as tracheal deviation
· Observation if less than 20%
· Thoracentesis is effective in 30-70% of patients
· Thoracostomy tube is the most commonly used technique
· Chemical pleurodesis is considered when there is persistent air leak
· Thoracotomy and mechanical pleurodesis will be necessary in up to 20% of patients
| Indications for Thoracotomy |
| Massive air leak that prevents re-expansion of the lung Persistent air leak over 7-10 days Second episode of spontaneous PTX Complications of PTX (hemothorax, empyema, chronic PTX) Specific surgical indications for underlying conditions Occupational indications (airline pilot, scuba diver, remote area) Previous contralateral PTX Bilateral simultaneous PTX Presence of large cysts |