Pathophysiology Pulmonary Infections

Upper respiratory tract infection

• Viral- Rhinovirus; adenovirus; coronaviruses; parainfluenza; respiratory syncytial virus; typically symptomatic

Upper respiratory tract infection S/S

nasal drainage, stuffiness, sore throat, PND, headache, malaise

Upper respiratory tract infection transmission

Contaminated surface, hand to mouth/eyes/nose

Rhinitis

inflammation of nasal passages

Sinusitis

inflammation of the sinuses

Rhinosinusitis

inflammation of the nasal and paranasal sinus mucosa; Pathogen: H. influenza, S. pneumoniae, rhinovirus

Rhinosinusitis S/S

face pain, purulent drainage, fever, HA

Rx: antibiotics, decongestants

Rhinosinusitis Bacterial

duration about 4 weeks; severe onset (fever, purulent drainage), worsening symptoms, or >10 days with symptoms

Rhinosinusitis Viral

duration is 5-7 days

allergic rhinitis

Type I hypersensitivity, an allergic reaction to airborne allergens that causes an increased flow of mucus

Allergic Rhinitis S/S

Nasal drainage (clear, watery), itching/burning eyes, nose, throat, nasal congestion

Rx: antihistamines, decongestants, nasalcorticosteroids, desensitization(immunotherapy)Allergic Rhinitis

Influenza

Viral infection of upper/lower respiratory tract- Often epidemic, can cause death- Children: highest rate of infection- Elderly/immunocompromised: higher severity•

Influenza

• Transmission: droplet infection• Incubation: 1-4 days• Contagious: 1 day before sx. to5 days after illness, longer for children, immunosuppressed

Influenza A

most common- highly contagious-- also affects birds, pigs, horses

Subtypes of Influenza A

Based on surface glycoproteins- Change antigens on cell membranes → newsubtypes

Hemaglutinin (HA)

part of the influenza A virus that allows for attachment to the cell and subsequent endocytosis; attachment proteins

Neuroaminidase (NA)

aids viral replication and release from host cell

Drift

minimal/small changes antigens

Shift

Both H and N antigens change

URI, viral pneumonia, complicating bacterial infection

3 syndromes of seasonal influenza

Influenza Pathophysiology

Upper airway infection- Damage ciliated/epithelial cells• Lower respiratory tract- Shedding, bronchial/alveolar cells• Secondary bacterial infection- ↓ natural defenses- ↑ bacterial adhesion

Influenza symptoms

Abrupt onset• Fever, malaise, chills, muscle aches, HA, watery nasal discharge, sore throat, dry cough• Peak: 3-5 days

viral pneumonia symptoms

Fever, tachypnea, cyanosis, tachycardia- Rapid progression of symptoms (within 1 day of influenza onset)- Survivors often develop acute pulmonary fibrosis

H1N1 S/S

similar to seasonal flu, some diarrhea/vomiting, extremely high fevers

Differences- Timing- Population more serious in adults < 25years old

Influenza prevention

Vaccine: everyone aged 6 months and older;

Especially high risk:- 6-59 months old; 50 years and older- Asthma, diabetes, chronic lung disease, HF, Pregnant women, Immunocompromised- Nursing facility & long-term care residents

Pneumonia

inflammation and infection of bronchioles and alveoli in lung parenchyma

Risk factors:

immunocompromised, elderly, lung disease

Pneumonia defense mechanisms

- Nasopharyngeal IgA- Cough reflex- Mucocilliary system- Alveolar macrophagesPneumonia

community acquired pneumonia

a type of pneumonia that results from contagious infection outside of a hospital or clinic; streptococcus pneumoniae most common

Hospital acquired pneumonia

pneumonia occurring 48 hours or longer after hospital admission and not incubating at the time of hospitalization. Not present on admission, nosocomial, usually bacterial, associated with antibiotic resistance, ventilator associated pneumonia

Typical pneumonia

Inhalation or aspiration of virulent organism• Inflammatory/immune response- Complement activation, antibody production- Opsonization of bacteria- Release inflammatory mediators andtoxins from organism → capillarypermeability & edema- Damage to bronchial/alveoli mucous membranes- Bronchioles/alveoli fill with fluid/debris (exudate)• Consolidation of lung tissue- Problems with ventilation and oxygenation- Recovery: macrophages digest fibrin & bacteria

Pneumonia S/S

Fever, chills, ↑RR- Cough, purulent sputum- Can progress to bacteremia and sepsis

Dx: CXR

Prevention - pneumococcal vaccines

Legionella pneumophilia

From water: Aerosolized water• Pneumonia with diarrhea, confusion, hyponatremia

Atypical pneumonias

Damage epithelium; invade alveolar septum/wall and interstitial lung tissue

Viral pneumonias

Frequently "interstitial", NOT alveolar; respiratory syncytial, influenza; atypical

Fungal Pulmonary Infections

Rare and self limiting in healthy individuals• Opportunistic infection• Pneumocystis Jiroveci (PJP)• Histoplasmosis, blastomycosis, coccidiomycosis- Found in soil, rotting wood/vegetation, river valleys- Regional distribution- Granuloma formation

Fungal pulmonary infections S/S

mild, flulike sx, productive cough, fever, night sweats, weight loss

Tuberculosis

• Risk factors: foreign born, HIV positive, congregatesettings (prisons, shelters)• Organism mycobacterium tuberculosis- Rod shaped, acid-fast, waxy capsule- Spread by droplet nuclei- Atypical infections• m. avium intracellulare, m. avium complex

Primary Tuberculosis

• Inhaled droplets activate inflammatory/ immune system• Macrophages and T lymphocytes seal off colony → Gohn Focus(aka: granuloma or tubercule)• Caseous necrosis: center ofgranuloma• Enter lymph → granuloma formation in lymph nodes• Gohn Complex = lung lesion and lymph node granuloma

Latent TB

one of two things that happens after a TB infection; organism contained, no active disease, lesions calcify

Primary progressive TB

(5%) one of two things that happens after a TB infection; organism continues to spread in lungs

Secondary TB

Reactivation of primary lesion or reinfection• More likely if chronic disease or immunocompromised: HIV, DM, malnutrition, elderly• Reactivation: necrotic tissue liquefies and drains into bronchus secondary activeTB

Latent TB

No symptoms of TB disease.• TB screen positive• CXR normal• Respiratory specimens are smear and culture negative.• Cannot spread TB bacteria to others.• Should consider treatment to prevent active TB disease

Active TB

Symptomatic• TB screen positive• CXR abnormal (usually)• Respiratory specimens are usually smear or culture positive• May spread TB bacteria to others• Needs treatment for TB disease

Tuberculosis S/S

Primary infection maybe asymptomatic• Low grade fever, sweats• Anorexia, weight loss• Cough - purulent, hemoptysis• Dyspnea• Other organ involvement- Death in 5 years if untreated

TB difficult to treat

- Due to resistance- Waxy capsule- Bacteria can live/divide within old lesionsTB - cont.

acute respiratory disease

-most common in infants/children

-small diameter airways

-lung maturity

infant respiratory distress syndrome

caused by immature lungs --> too little surfactant in the alveoli; lungs collapse with each breath (atelectasis), increased work of breathing and hypoxia, hyaline membrane forms

infant respiratory distress syndrome S/S

cyanosis, retractions, ↑ RR

Tx: O2, CPAP, surfactant,mechanical ventilation,steroids to motherduring preterm labor

bronchopulmonary dysplasia

chronic lung disease in infants due to mechanical ventilation or prolonged O2; alveolar hypoplasia, alveolar fibrosis

Bronchopulmonary Dysplasia S/S

Persisten hypoxia, chronic respiratory distress, retractions, tachycardia, rapid RR;

Tx: mechanical ventilation

Viral Croup

viral infection, acute laryngotracheobronchitis, obstructive subglottic region (below vocal cords)

Viral croup S/S

barking cough, hoarseness, inspiratory stridor

May subside with humidity, cold air

Worsen at night

Croup cough sound, can progress to airway obstruction

Tx: epinephrine, humidified O2,trach or endotracheal tube (if severe)

Epiglottitis

Inflammation/edema epiglottis/pharynx• Common causes: H.Influenza, strep, staph• Acute onset• Edema epiglottis can cause airway obstruction

Epiglottitis S/S

Sore throat, stridor, fever, mouth open/chin thrust forward, drooling

Tx: Abx, maintain airway withendotrachealtube or tracheostomy