pathophysiology chapter 22

CHAPTER 22

OBSTRUCTIVE PULMONARY DISORDERS

OBSTRUCTIVE PULMONARY DISORDERS

• Manifested by increased resistance to airflow• Classifications• Obstruction from conditions in the wall of the

lumen• Obstruction resulting from increasing pressure

around the outside of the airway lumen • Obstruction of the airway lumen

OBSTRUCTION FROM CONDITIONS IN THE WALL OF THE LUMEN

Asthma• Etiology• Airway obstruction that is reversible (not

completely in some patients)• Airway inflammation• Increased airway responsiveness to a variety of

stimuli


(CONT.)Asthma• Statistics• Occurs in 5% to 12% of U.S. population• Most common chronic disease of children• High-risk populations• African Americans• Inner-city dwellers• Premature/low-birth-weight children


(CONT.)Asthma• Predisposing factors• Genetic for atopy and structural (smaller airways)• Chromosomes 5, 11, 14

• History of hay fever, eczema• Family history• Positive skin test reactions to allergens


(CONT.)Asthma• Extrinsic (allergic)• 1/3 to ½ of asthma cases• An IgE-mediated response is common• Clinical manifestations• Elevated IgE levels• Allergic rhinitis• Eczema• Positive family history of allergy• Attacks associated with seasonal, environmental or

occupational exposure


(CONT.)Asthma• Extrinsic• Mechanism of action• Immediate phase

• Initiated by exposure to specific antigen that has previously sensitized mast cells in airway mucosa

• Antigen reacts with antibody on surface of mast cell • Mast cell releases packets of chemical mediator

substances


(CONT.)Asthma• Extrinsic• Mechanism of action• Chemical mediators released

• Histamine• Slow-reacting substances of anaphylaxis (leukotrienes)• Prostaglandins• Bradykinins• Eosinophilic chemotactic factor• Serotonin

OBSTRUCTION FROM CONDITIONS IN THE WALL OF

THE LUMEN (CONT.)


THE LUMEN (CONT.)Asthma• Extrinsic• Mechanism of action• Normal respiratory epithelium is denuded and

replaced by goblet cells• Alterations in epithelial integrity


THE LUMEN (CONT.)Asthma• Extrinsic• Mechanism of action• Increased microvascular permeability

• Mucosal edema• Inflammatory exudates• Bronchoconstriction• Leakage


THE LUMEN (CONT.)Asthma• Extrinsic • Mechanism of action• Late phase

• Arrival of recruited leukocytes signals initiation• More mediator release causes damage to epithelium


THE LUMEN (CONT.)Asthma• Extrinsic • Mechanism of action• Epithelial damage

• Hypertrophied smooth muscle• Edema• Mucous gland hypertrophy• Mucus in lumen


THE LUMEN (CONT.)Asthma• Inflammation of airway• Causes• Acute bronchospasm (bronchoconstriction)• Mucosal edema• Mucous plug formation• Airway wall remodeling


THE LUMEN (CONT.)


THE LUMEN (CONT.)Asthma• Pathogenesis• Immunohistopathologic features• Denudation of airway epithelium• Collagen deposition beneath the basement

membrane• Edema• Mast cell activation• Inflammatory cell infiltration by neutrophils,

eosinophils, and lymphocytes


THE LUMEN (CONT.)Asthma• Common symptoms• Wheezing• Feeling of tightness of chest• Dyspnea• Cough (dry or productive)• Increased sputum production (thick, tenacious,

scant, and viscid


THE LUMEN (CONT.)Asthma• Symptoms of severe attack• Use of accessory muscles of respiration• Intercostal retractions• Distant breath sounds with inspiratory wheezing• Orthopnea• Agitation• Tachypnea• Tachycardia


THE LUMEN (CONT.)Asthma• Diagnosis• Physical findings• Cough• Wheezing• Hyperinflated chest• Decreased breath sounds


THE LUMEN (CONT.)Asthma• Diagnosis• Radiographic finding• Hyperinflation with flattening of the diaphragm

• Sputum examination• Charcot-Leyden crystals (formed from crystallized

enzymes from eosinophilic membranes)• Eosinophils• Curschmann spirals (mucous casts of bronchioles)


THE LUMEN (CONT.)Asthma• Diagnosis• Pulmonary function tests• Forced expiratory volumes decrease• Peak expiratory flow rate (PEFR)

• Determines index of airway function• FEV1 measured over 1 second• FVC• Ratio of FEV1/FVC before and after administration of

short-acting bronchodilator • Obstruction indicated by FEV1/FVC <75%


THE LUMEN (CONT.)


THE LUMEN (CONT.)Asthma• Diagnosis• ABG• Normal during mild attack• Respiratory alkalosis and hypoxemia as

bronchospasm increases in intensity• PaCO2 elevation


THE LUMEN (CONT.)Asthma• Diagnosis • Skin testing • Young patients with extrinsic asthma

• Bronchial provocation testing• Test with histamine or methacholine

• CBC• Elevated WBCs • Elevated eosinophils


THE LUMEN (CONT.)Asthma• Treatment• Avoid triggers• Environmental control • Removal of allergens• Air purifiers• Air conditioners

• Preventive therapy• Desensitization (allergen specific immunotherapy)


THE LUMEN (CONT.)


THE LUMEN (CONT.)Asthma• Treatment• Medications• O2 therapy• Small-volume nebulizers• B2 agonists• Corticosteroids• Leukotriene modifiers• Mast cell inhibitors


THE LUMEN (CONT.)


THE LUMEN (CONT.)Acute Bronchitis• Etiology• Acute inflammation of the trachea and bronchi• Causes• Viral

• Influenza virus A or B• Parainfluenza virus• Respiratory syncytial virus• Coronavirus• Rhinovirus• Coxsackievirus• Adenovirus


THE LUMEN (CONT.)Acute Bronchitis• Etiology • Causes• Nonviral

• Streptococcus pneumoniae• Haemophilus influenzae• Mycoplasma• Moraxella• Chlamydia pneumoniae


THE LUMEN (CONT.)Acute Bronchitis• Etiology • Causes • Heat• Smoke inhalation• Inhalation of irritant chemicals• Allergic reactions


THE LUMEN (CONT.)Acute Bronchitis• Pathogenesis• Airways become inflamed and narrowed from

capillary dilation• Swelling from exudation of fluid• Infiltration with inflammatory cells increased

mucus production• Loss of ciliary function• Loss of portions of the ciliated epithelium


THE LUMEN (CONT.)Acute Bronchitis• Clinical manifestations• Cough (productive or nonproductive)• Low-grade fever• Substernal chest discomfort• Sore throat• Postnasal drip• Fatigue


THE LUMEN (CONT.)Acute Bronchitis• Diagnosis• Clinical presentation• Chest x-ray to distinguish acute bronchitis from

pneumonia


THE LUMEN (CONT.)Acute Bronchitis• Treatment• Antibiotic therapy (bacterial)• Codeine-containing medications (for cough)• Increase fluid intake• Avoid smoke• Use a vaporizer in bedroom


THE LUMEN (CONT.)Chronic Bronchitis• Etiology• Type B COPD, “blue bloater”• Chronic or recurrent productive cough >3 months

>2+ successive years• Persistent, irreversible• Typical patient is overweight (1:2 male to female

ratio)• >30-40 years• Commonly associated with emphysema


THE LUMEN (CONT.)Chronic Bronchitis• Cause• Cigarette smoking (90%)• Repeated airway infections• Genetic predisposition• Inhalation of physical or chemical irritants


THE LUMEN (CONT.)Chronic Bronchitis• Pathogenesis• Chronic inflammation and swelling of the bronchial

mucosa resulting in scarring• Elevated IL8 levels recruit neutrophil activation• Elevated CD8 T-lymphocytes• Extend into surrounding alveoli• Prevent proper oxygenation and potentiate airway

obstruction


THE LUMEN (CONT.)Chronic Bronchitis• Pathogenesis• Hyperplasia of bronchial mucous gland/goblet

cells• Increased mucus production• Mucus combines with purulent exudate (bronchial

plugs) to form mucous plug


THE LUMEN (CONT.)


THE LUMEN (CONT.)Chronic Bronchitis• Pathogenesis • Increased bronchial wall thickness• Resistance increases work of breathing• Increased O2 demands• Produce ventilation-perfusion mismatch with

hypoxemia and hypercarbia• Increases pulmonary artery resistance


THE LUMEN (CONT.)


THE LUMEN (CONT.)Chronic Bronchitis• Pathogenesis• Pulmonary hypertension• Inflammation in bronchial walls with vasoconstriction

of pulmonary blood vessels and pulmonary arteries• Right-sided heart failure may occur r/t high

pulmonary resistance

OBSTRUCTION CONDITIONS IN THE WALL FROM OF THE

LUMEN (CONT.)Chronic Bronchitis• Clinical manifestations• SOB on exertion • Excessive sputum• Chronic cough (more severe in mornings)• Evidence of excess body fluids (edema,

hypervolemia)• Cyanosis (late sign)


LUMEN (CONT.)


LUMEN (CONT.)Chronic Bronchitis• Diagnosis• Chest x-ray• Increased bronchial vascular markings• Congested lung fields• Enlarged horizontal cardiac silhouette• Evidence of previous pulmonary infection


LUMEN (CONT.)Chronic Bronchitis• Diagnosis• Pulmonary function tests• Normal total lung capacity (TLC)• Increased residual volume (RV)• Decreased FEV1


LUMEN (CONT.)Chronic Bronchitis• Diagnosis • Arterial blood gas (ABG)• Elevated PaCO2• Decreased PO2• Develop early in disease process


LUMEN (CONT.)Chronic Bronchitis• Diagnosis• ECG• Atrial arrhythmias• Evidence of right ventricular hypertrophy

• Secondary polycythemia• R/t continuous or nocturnal hypoxemia


LUMEN (CONT.)Chronic Bronchitis• Treatment• Medications• Inhaled short-acting B2 agonists• Inhaled anticholinergic bronchodilators• Cough suppressants• Antimicrobial agents (bacterial infections)• Inhaled/oral corticosteroids• Theophylline products


LUMEN (CONT.)Chronic Bronchitis• Treatment• Low-dose O2 therapy• Patients with PaO2 levels <55 mm Hg


LUMEN (CONT.)Chronic Bronchitis• Management• Smoking cessation• Bronchodilator therapy• Reduction to exposure of irritants• Adequate rest• Proper hydration• Physical reconditioning• Treadmill/stationary bike• Alternating rest and exercise

OBSTRUCTION RELATED TO LOSS OF LUNG PARENCHYMA

Emphysema• Etiology• Type A COPD• “Pink puffer”• Young to middle-age adults <50 years

(uncommon)• Hereditary low α1-antitrypsin activity in lung

• >50 years (develops over time)


(CONT.)


(CONT.)Emphysema• Etiology• Causes• Smoking >70 pack/year• Air pollution• Certain occupations (mining, welding, working with or

near asbestos)• α1-Antitrypsin deficiency


(CONT.)Emphysema• Etiology• Smoking causes alveolar damage• Inflammation in lung tissue leading to release of

proteolytic enzymes• Inactivates α1-antitrypsin (protects lung parenchyma)


(CONT.)


(CONT.)Emphysema• Pathogenesis• Release of proteolytic enzymes from inflammatory

cells (neutrophils, macrophages) leading to alveolar damage

• Reduction in pulmonary capillary bed• Exchange of O2 and CO2 between alveolar and

capillary blood impaired


(CONT.)


(CONT.)Emphysema• Pathogenesis• Loss of elastic tissue in lung• Results in decrease in size of smaller bronchioles• Results in loss of radial traction (holds airway open)


(CONT.)


(CONT.)Emphysema• Classifications• Centriacinar (centrilobular)• Associated with chronic bronchitis, emphysema• Destroys respiratory bronchioles

• Panacinar (panlobular)• Destroys the alveoli

• Paraseptal• Affects the peripheral lobules


(CONT.)


(CONT.)Emphysema• Clinical manifestations• Progressive, exertional dyspnea• Increased SOB for past 3-4 years• Thin • R/t increased caloric expenditure and decreased

ability to consume adequate calories• Use of accessory muscles• Pursed-lip breathing• Cough (minimal or absent)


(CONT.)


(CONT.)Emphysema• Diagnosis• Patient history and physical finding• Thin, wasted individual hunched forward• Barrel chest• Digital clubbing• Decreased breath sounds, lack of crackles and

rhonchi with prolonged expiration• Decreased heart sounds• Decreased diaphragmatic excursion


(CONT.)Emphysema• Diagnosis • Pulmonary function tests (PFTs)• Increased functional residual capacity• Increased RV• Increased TLC• Decreased FEV• Decreased FVC


(CONT.)Emphysema• Diagnosis• Chest x-ray• Hyperventilation• Low, flat diaphragm• Presence of blebs or bullae• Narrow mediastinum• Normal or small “vertical” heart


(CONT.)Emphysema• Diagnosis• ABG• Mild increase in PaO2• Normal PaCO2 (elevated in late stages)

• ECG• Normal, show tall P waves• Sinus tachycardia• Supraventricular arrhythmias• Ventricular irregularities


(CONT.)Emphysema• Treatment• O2 therapy• Medications• Inhaled short-acting B2 agonists• Inhaled anticholinergic bronchodilators• Cough suppressants• Antimicrobial agents (infections)• Inhaled/oral corticosteroids• Theophylline products

OBSTRUCTION OF AIRWAY LUMEN

Bronchiectasis• Etiology• Dilation of bronchial wall• Obstructive and suppurative (pus-forming)

disorder• Increased risk in children• Acquired

• Rare• Congenital

• 50% associated with cystic fibrosis

OBSTRUCTION OF AIRWAY LUMEN (CONT.)

Bronchiectasis• Classifications• According to bronchial shape• Saccular

• Cavity-like dilatations• Cylindrical• Fusiform

• Combination of saccular and cylindrical


Bronchiectasis• Pathogenesis• Recurrent infection and infection of bronchial walls

leads to persistent dilation• Inflammation results in destruction of walls• Destructive process leads to loss of ciliated

epithelium• Transforms to squamous cell and pus formation• Leads to obstruction


Bronchiectasis• Clinical manifestations• Chronic, productive cough • Purulent, foul-smelling, green, or yellow sputum• Hemoptysis• Fever, night sweats• Moist crackles including bases, rhonchi• Halitosis (bad breath)• Skin pallor• Digital clubbing (infrequent)


Bronchiectasis• Clubbing• Caused by prolonged, decreased oxygenation• Associated with lymphocytic extravasation,

increased vascularity, and edema• Severity parallels the severity of disease


Bronchiectasis• Complications• Malnutrition• Recurrent pneumonia• Right ventricular failure• Secondary visceral abscesses


Bronchiectasis• Diagnosis• History of chronic, productive cough• Chest x-ray• Small cysts, bronchial wall thickening, increased

bronchial markings• PFTs• Decreased airflow and vital capacity

• ABG• Decreased PaO2, Increased PaCO2

• CT• Best choice for diagnosis


Bronchiectasis• Treatment• Antibiotic therapy• Bronchodilators• Vigorous chest percussion and postural drainage• Proper hydration and nutrition• Bronchoscopy (if severe)• Surgical removal (if severe)


Bronchiolitis• Widespread inflammation of bronchioles

due to infectious agents• Occasionally related to allergic reactions• Occurs winter to spring• Children <2 years• Adults • Smoking, toxic fumes, immunosuppression


Bronchiolitis• Common organisms• Viral• RSV, influenzavirus (A, B, C)

• Bacterial• H. influenzae, pneumococci, hemolytic streptococci,

mycoplasma, chlamydia, Pneumocystis jiroveci


Bronchiolitis• Pathogenesis• Proliferation and necrosis of bronchiolar

epithelium• Production of thick, tenacious mucus• Airway obstruction• Atelectasis• Hyperinflation


Bronchiolitis• Pathogenesis• Possible mechanisms of airway obstruction• Development of inflammatory exudate• Release of chemical mediators• Inflammation• Goblet cell metaplasia• Increased bronchial muscle mass


Bronchiolitis• Clinical manifestations• Severity and course range from mild-fatal• Wheezing r/t bronchospasm• Crackles• Decreased breath sounds• Retractions• Increased sputum• Dyspnea• Tachypnea• Low-grade fever


Bronchiolitis• Diagnosis• Elevated WBC• Chest x-ray• Enlarged air sacs, interstitial infiltrates, atelectasis,

severe hyperinflation• PFT• Severe obstruction to airflow

• Nasal swab


Bronchiolitis• Treatment• Adequate oxygenation• Bronchodilator agents• Corticosteroids• Sedation (anxiety)• Hydration, administration of medications• Antiviral/antibiotics• Smoking cessation


Cystic Fibrosis• Etiology• Autosomal recessive disorder of exocrine glands• Dysfunction of CFTR gene (60%-75% of patients)

• 1:2000-3000 Caucasian births• >18 years (35%)• Affects pancreas, intestinal tract, sweat glands,

lungs, infertility (male)• Classified as Airflow or suppurative (pus-forming)


Cystic Fibrosis• Clinical manifestations• History of cough in young adult or child• Thick, tenacious sputum• Recurrent pulmonary infections• Recurrent episodes of bronchitis


Cystic Fibrosis• Clinical manifestations• Physical findings• Digital clubbing (late) • Dyspnea, tachypnea• Sternal retractions• Unequal breath sounds• Moist basilar crackles and rhonchi• Barrel chest hyperresonant to percussion


Cystic Fibrosis• Clinical manifestations• Nutritional assessment• Depleted fat stores• Steatorrhea (fatty stools)• Anorexia• Decreased growth rate in children (wt, ht, head circ)• Decreased mid-arm indices


Cystic Fibrosis• Diagnosis• ABG• PFT• Decreased VC, airflow, TV• Increased airway resistance, functional residual

capacity• Sputum C&S• Chest x-ray• Patchy atelectasis, bronchiectasis, obstructive

emphysema, cystic lung fields, peribronchial thickening


Cystic Fibrosis• Diagnosis • 72-hour stool collection• Determine fat absorption and fecal fat excretion

• Sweat test (pilocarpine iontophoresis)• Elevated Na, Cl levels• 98% have levels >60 mEq/L (children) >80 mEq/L

(adult)• Genetic testing• Genetic marker AF-508 confirms diagnosis


Cystic Fibrosis• Treatment• Postural drainage and chest physiotherapy

(priority)• Medications• Bronchodilators• High dose antibiotics (bacterial infections)• Influenza vaccine

• Heart-lung or lung transplant


Cystic Fibrosis• Treatment• Nutritional therapy• Unrestricted fat consumption

• 30% of caloric intake• High protein• Vitamin supplements• Pancreatic enzymes• Intake of 150% normal caloric intake


Acute Tracheobronchial Obstruction• Etiology• Causes• Aspiration of foreign body (most often in left lung)• Malpositioned endotracheal tube• Laryngospasm• Epiglottitis• Trauma• Swelling (smoke inhalation)• Postsurgical blood clot• Compression of bronchus/trache (tumor, enlarged

lymph nodes


Acute Tracheobronchial Obstruction• Clinical manifestations• Partial obstruction• Stridor• Sternal and intercostal retractions• Wheezing• Nasal flaring• Tachypnea, dyspnea• Tachycardia• Use of accessory muscles


Acute Tracheobronchial Obstruction• Clinical manifestations• Complete obstruction• No air movement heard with auscultation (complete

obstruction)• Inability to talk• Tachycardia• Cyanosis• Rapid progression to unconsciousness


Acute Tracheobronchial Obstruction• Diagnosis• Based on clinical features• ABG• Hypoxemia, hypercarbia

• Chest x-ray• Location of obstruction


Acute Tracheobronchial Obstruction• Treatment• Open obstructed airway as soon as possible• Heimlich to expel foreign body• Suction• Emergency tracheostomy (obstruction in

subglottic region or above)


Epiglottitis• Etiology• Rapidly, progressive cellulitis of epiglottis and

adjacent soft tissues• Subtype of croup• Children 2 to 4 years• Common organisms• Pneumococci, streptococci, staphylococci


Epiglottitis• Pathogenesis• Infecting agent localizes in epiglottis and

pharyngeal structures• Causes rapid and potentially fatal inflammation • Swelling • Airway obstruction


Epiglottitis• Clinical manifestations• Drooling• Dysphagia, dysphonia• Rapid onset of fever• Inspiratory stridor and retractions• Oropharynx edematous and cherry red• Child sits in “sniffing dog” position• Provides best airway patency


Epiglottitis• Diagnosis• Direct or fiberoptic visualization of epiglottis• Lateral neck x-ray• Classic “thumbprint sign”

• CBC• Leukocytosis with shift to left


Epiglottitis• Treatment• True medical emergency• May necessitate intubation• Antibiotic therapy• Preventative• Hib vaccine


Croup Syndrome• Etiology• A number of acute, viral inflammatory diseases of

larynx, trachea, and bronchi• Laryngotracheobronchitis (viral croup)• Epiglottitis• Bacterial tracheitis

• Occurs in fall and early winter• Children 6 months to 3 years


Croup Syndrome• Etiology• Causes• Parainfluenza virus type 2 and 3• RSV• Influenzavirus• Adenovirus• Mycoplasma pneumoniae


Croup Syndrome• Pathogenesis• Viral agent of subglottic area• Infectious agent causes inflammation along entire

airway• Leads to edema in subglottic area


Croup Syndrome• Clinical manifestations• History of upper respiratory infection or cold• Barking cough with stridor• Low-grade fever (may be absent)• Severe cases• Stridor at rest• Retractions• Cyanosis


Croup Syndrome• Diagnosis• Clinical signs and symptoms• Lateral neck films• Subglottic narrowing and normal epiglottis

• Laryngoscopy• Confirm presence or rule out epiglottitis


Croup Syndrome• Treatment• Mist therapy• Oral hydration• Avoidance of stimulation• O2 therapy, pulse oximetry (hospitalized)• Nebulized epinephrine (relieves airway

obstruction)• Endotracheal intubation (respiratory failure)

DIAGNOSTIC TESTSPulmonary Function Testing (PFT)• Demonstrates obstruction of airflow in

lungs• Spirometry• Determines severity and diagnosis of COPD• Patient inhales deeply and exhales as quickly as

possible until maximal air is exhaled

DIAGNOSTIC TESTS (CONT.)Pulmonary Function Testing (PFT)• Spirometry• Forced vital capacity• Total volume of air exhaled• Time required for exhaling the air is also measured

• Forced expiratory volume in 1 second• Volume exhaled in 1st second is reliable and index of

obstructive airway disease

DIAGNOSTIC TESTS (CONT.)

DIAGNOSTIC TESTS (CONT.)Pulmonary Function Testing (PFT)• Spirometry• Airflow obstruction• FEV1/FVC ratio >75%

• No significant obstruction • FEV1/FVC ratio between 60% and 70%

• Mild obstruction• FEV1/FVC ratio 50% to 60%

• Moderate obstruction• FEV1/FVC ratio <50%

• Severe obstruction

DIAGNOSTIC TESTS (CONT.)Spirometry• Inhaled bronchodilator given, repeat test in

15-20 minutes• Positive bronchodilator response• FEV1 improves >15% = positive bronchodilator

response• Partially reversible bronchospasm of smooth muscle

(asthma, asthmatic bronchitis)

DIAGNOSTIC TESTS (CONT.)Spirometry• Diffusion capacity• Measures ability of alveolar gases to diffuse into

capillary blood• Valuable for determining fibrosis or destruction of

membrane

DIAGNOSTIC TESTS (CONT.)Spirometry• Total lung capacity• Normal RV/TLC 30% to 35%• Breathing mixtures of inert gas (helium)• Volume composed of FVC and RV (residual volume• Volume voluntarily exhaled all of the air from lungs

• ABG• Assesses oxygenation and acid-base status

DIAGNOSTIC TESTS (CONT.)Spirometry• Diagnosis of obstructive disorder• Decreased FEV1• Low FEV1/FVC ratio (<70%)• Improvement in FEV1 after use of bronchodilator

(asthma)• Increased residual volume• Increased functional residual capacity

DIAGNOSTIC TESTS (CONT.)Bronchial Provocation Tests• Induction of bronchospasm by inhalation of

various agents• Series of ventilations administered• Identify hyper-reactive airways and identify source

of bronchospasm• Done only with emergency support services• Hyperactivity = fall >20%

pathophysiology chapter 22

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