Obstructive lung disease

Obstructive lung disease Microchapters
Overview
Classification Asthma COPD Bronchiolitis Bronchiectasis Heart failure Tuberculosis Lymphangioleiomyomatosis Cystic fibrosis
Spirometry Findings in Various Lung Conditions
Approach to Lung Disorders
Differentiating Obstructive Lung Disease from other Diseases

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Usama Talib, BSc, MD [2], Feham Tariq, MD [3], Dildar Hussain, MBBS [4]

Overview

An obstructive lung disease is a group of diseases characterized by various deformities that result in the collapse of airways. Patients suffering from obstructive lung disease usually present with shortness of breath due to damage to the airways within the lungs. This results in an inability to exhale air completely and an abnormally high amount of air may still present in the lungs after the end of full expiration. One of the main etiology of the obstructive lung disease is long-term exposure to substances that irritate and damage the lung epithelium and lung parenchyma. This includes cigarette smoke, air pollution, chemical fumes, or dust etc. Patients are usually asymptotic during the initial phase of the disease. However, symptoms usually become more evident as the disease process gets worse. The symptoms usually include a productive cough, difficulty in breathing, wheezing, and tightness in the chest. These diseases include asthma, COPD, bronchiolitis, bronchiectasis, heart failure, tuberculosis, cystic fibrosis, and lymphangioleiomyomatosis. Obstructive lung diseases present with an obstructive pattern that is an increase in total lung capacity (TLC), increase in respiratory volume (RV), a decrease in forced vital capacity (FVC), a decreased forced expiratory volume (FEV1), and a decreased FEV1/FVC, on pulmonary function tests.

Classification

Various diseases that present with an obstructive pattern on pulmonary function tests include:

• Asthma
• COPD
• Bronchiolitis
• Bronchiectasis
• Heart failure
• Tuberculosis
• Lymphangioleiomyomatosis
• Cystic fibrosis

Spirometry Findings in Various Lung Conditions

Spirometry can help distinguish obstructive lung disease from restrictive lung disease. On spirometry the findings include:

Approach to Lung Disorders

Spirometry

Low FEV1/FVC ratio

Normal to high FEV1/FVC ratio

Obstructive Lung Disease

Restrictive Lung Disease

Bronchodilator therapy

DLCO

Increased FEV1

No change in FEV1

Normal DLCO

Decreased DLCO

Asthma

COPD

Chest wall disorders

Interstitial Lung Disease

Differentiating Obstructive Lung Disease from other Diseases

Various diseases presenting with obstructive pattern on pulmonary function tests can be differentiated from each other as follows:

Diseases	Clinical manifestations										Diagnosis
	Symptoms					Signs					Lab findings	PFT				Imaging			Gold standard	Other features
	Cough	Dyspnea	Hemoptysis	Fever	Weight loss	Cyanosis	Clubbing	JVD	Peripheral edema	Auscultation		ABGs	FEV1/FVC	TLC	DLCO
																CXR	CT scan	Other tests
Asthma	+	+	±	±	−	−	−	−	−	Wheeze Rhonci	↑IgE	Normal	↓FEV1 FEV1:FVC =<0.7	↑	Normal/↑	Pulmonary hyperinflation	Extensive air trapping	Bronchoprovocation testing Peak expiratory flow measurement	Physical Exam Spirometery	Associated with: Allergic rhinitis GERD and obesity can mimic asthma
Chronic bronchitis	+	+	±	+	−	−	−	−	−	Wheeze Rhonci Egophony Rales ↓Bronchial breath sounds.(present in consolidation)	↑Procalcitonin	Normal	↓FEV1	↑	Normal	Thickening of the bronchial walls in the lower lobes	Thickening of the bronchial walls in the lower lobes	Microbiological testing is done in cases of: Influenza Pertusis	Clinical diagnosis Chest radiograph	Secondary to URTI
Bronchiolitis	+	+	−	+	−	−	−	−	–	Wheeze Crackles		Normal	↓	↑	↓	Bronchovascular markings	Air trapping Bronchial wall thickening	Bronchoscopy Lung biopsy	Thoracoscopic lung biopsy	Can be associated with: Organ transplantation
Emphysema	+	+	–	+	+	+	+	–	–	Expiratory wheeze Hyperinflation	↓alpha-1 antitrypsin deficency	Respiratory alkalosis Metabolic acidosis	↓FEV1	↑	–	Flattening of the diaphragm Vertical heart	Small subpleural collections of gas Centriacinar emphysema Panacinar emphysema Paraseptal emphysema	Pulse oximetry	Physical Exam Spirometery	Barrel Chest
Bronchiectasis	+	+	+	+	–	+	+	–	–	Rhonci Wheeze Crackles	↑Neutrophils		↓FEV1:FVC	↑	↓	Tram track opacities	Signet-ring sign Airway dilation	Flexible bronchoscopy	HRCT	Chronic productive cough
Heart failure	+	+	–	–	–	+	–	+	+	S3 gallop Wheeze Rales	↑Pro-BNP ↑Troponin Anemia Hyponatremia ↑BUN ↑Creatinine	Respiratory alkalosis		Normal	Normal	Bat wing appearance Cardiomegaly Pulmonary congestion Pulmonary interstitial edema Pleural effusion		MRI Cardiac catheterization Exercise testing Ambulatory ECG monitoring
Tuberculosis	+	+	+	+	+	–	–	–	–	Diminished breath sounds Rhonci/wheeze	↑C-reactive protein Normocytic anemia			↑		Upper lobe infiltrate Upper lobe cavitation Hilar adenopathy Solitary nodules Pleural effusion Mediastinal lymphadenopathy Fibrotic leisons Distortion of the lung parenchyma	Centrilobular 2 to 4 mm nodules Branching linear lesions Patchy small lower lobe infiltrates
Lymphangioleiomyomatosis	+	+	+(<5%)	-	-	-	+(rare)	-	+	Wheeze Hyperinflation Absent or ↓Breath sounds	↑Vascular endothelial growth factor-D	Respiratory acidosis in severe disease	↓FEV1:FVC	Normal	↓DLCO	Ground glass appearance Interstetial pulmonary edema Septal thickening	Pulmonary cyst Pnuemothorax Pleural masses Pleural thickening Mediastianl lymphadenopathy Pleural effusion	VQ Scan PET Scan Advanced lymphatic imaging	Surgical lung biopsy	Chylothorax(most common lymphatic manifestation) Chyloperitonium Renalangiomyolipoma
Status Asthmaticus	+	+	-	±	-	-	-	+	-	Wheeze Absent or ↓Breath sounds	↑TLC ↑Glucose	↑PCO2 ↓PO2	↓FEV1:FVC < 30% of predictive value	↑TLC	↑DLCO	Pulmonary hyperinflation Atypical presentation	-	Peak expiratory flow<50% of baseline	Clinical diagnosis	Pulses paradoxus
Cystic fibrosis	+	+	+	+	-	+	+	-	-	Crackles	Sweat Chloride test: >60 mEq/L	↑PCO2 ↓PO2	↓FEV1:FVC	↑TLC	↓ In severe lung impairment