Clin Pharm - Lower Respiratory Tract Infections (LRTI)

affect the structures below the larynx, primarily the trachea, bronchi, bronchioles, and alveoli.

Lower Respiratory Tract Infections (LRTI)

Inflammation of the large airways (bronchi).

Bronchitis

Viral infection of the small airways (infants).

Bronchiolitis

Infection involving the lung parenchyma and air sacs.

Pneumonia

The Common Chest Cold & Inflammatory Response

Acute Bronchitis

Respiratory viruses are the predominant infectious agents in acute bronchitis:

• Influenza A and B

• Respiratory Syncytial Virus (RSV)

• Parainfluenza & Adenovirus

• Environmental triggers: Air pollution & cigarette smoke

Acute Bronchitis: Inside the Bronchial Tree

Inflammation: Infection causes hyperemic and edematous mucous membranes. Tracheal and bronchial linings swell, narrowing the airway.

Destruction: Respiratory epithelium destruction affects mucociliary function. Desquamated cells and thick secretions impair clearance.

Reactivity: Recurrent infections may lead to airway hyperreactivity, potentially contributing to future asthma or COPD pathogenesis

Acute Bronchitis Clinical Presentation

Cough: The hallmark symptom. May be nonproductive initially, progressing to mucopurulent sputum. Can persist for 3+ weeks.

Fever: Rarely exceeds 39℃ . Common with Adenovirus or Influenza.

Progression: Often begins as an upper respiratory infection with nonspecific complaints like nasal congestion.

Diagnosis: Bacterial cultures are limited; etiologic diagnosis is rarely necessary for routine care.

Acute Bronchitis Supportive Care Strategies

Goals:

• Comfort & Hydration

• Primary treatment is symptomatic. Antibiotics are strongly discouraged for routine use.

  • Encourage fluids to thin secretions.

  • Bedrest for comfort as needed.

  • Dextromethorphan for bothersome cough.

Supportive Care Strategies for acute bronchitis drug with dose

Adult Antipyretics: 650mg Acetaminophen q 6-8 hours

Pediatric Dosing: 10-15mg/kg per dose

Avoid aspirin in children under 19 due to __risk

Reye Syndrome

A Component of COPD: The Rule of Three and Two

Chronic Bronchitis

What rule for Chronic Bronchitis

Presence of a chronic cough productive of sputum lasting more than 3 consecutive months of the year for 2 consecutive years.
Excludes underlying etiologies like bronchiectasis or tuberculosis.

3-3-2 Rule

Clinical Hallmarks of Chronic Bronchitis

Morning Sputum: Largest quantity expectorated upon arising.

Sputum Character: Tenacious; ranges from white to yellow-green.

Physical Signs: Cyanosis and clubbing of digits in advanced disease.

Auscultation: Rales, rhonchi, wheezing, and prolonged expiratory phase.

Common Bacterial Isolates from Sputum in Acute Exacerbations (AECB) of Chronic Bronchitis (in order):

H. influenzae; 5%

M. catarrhalis; 20%

S. pneumoniae; 30%

Others (P. aeruginosa, E. coli); 45%

*Note: H. influenzae strains are often B-lactamase positive and nontypeable

Managing Chronic Disease Standard Therapies for Chronic Bronchitis

• Vaccines: Pneumococcal & Annual Influenza.

• Bronchodilators: Albuterol (SABA) or Salmeterol (LABA).

• Muscarinic Antagonists: Ipratropium (SAMA) or Tiotropium (LAMA).

• Combination Therapy: LABA + Inhaled Corticosteroid.

Managing Chronic Disease for Chronic bronchitis (Anthonisen Criteria)

Benefit from antibiotics if 2+ are present:

1. Increase in Shortness of Breath

2. Increase in Sputum Volume

3. Increase in Sputum Purulence

Acute Viral Infection of the Lower Tract in Infants

Bronchiolitis

Bronchiolitis Key Characteristics

• Primary Cause: Respiratory Syncytial Virus (RSV) - 75% of cases.

• Affects 50% of infants in Year 1; 100% by Year 2.

• Signs: Nasal flaring, grunting, retractions, and "noisy breathing."

• Dehydration is common due to limited oral intake and coughing.

Mainstays of Therapy for Bronchiolitis

Standard Care: Reassurance, antipyretics, and fluid intake. Usually self-limiting.

Severe Cases: Humidified Oxygen therapy and IV fluids for hypoxic or dehydrated infants

Nebulization: 3% Hypertonic Saline is supported for hospitalized infants. Ribavirin reserved for severe illness.

Severe Sepsis and parenchyma Infection

Pneumonia

What classification of Pneumonia

Definition:Onset outside hospital or <48h adm.

Key Risk Factors: Age >65, DM, Smoking, Chronic heart/lung disease.

Community-Acquired Pneumonia

What classification of Pneumonia

Definition: Onset >48h after admission

Key Risk Factors: COPD, Coma, Acid-reducing drugs, Witnessed aspiration.

Hospital-Acquired Pneeumonia

What classification of Pneumonia

Definition: Onset >48h after intubation

Key Risk Factors: MDR risk, 5+ days hospitalization, ARDS.

Ventilator-Associated Pneumonia

Routes of Infection for Pneumonia

Direct Inhalation: Infectious droplets from the environment are inhaled directly into the lower tract.

Aspiration: Oropharyngeal contents containing pathogens enter the lungs (common in elderly/altered consciousness)

Hematogenous: Pathogens spread from a distant infection site through the bloodstream to the lungs.

Signs and Symptoms of Pneumonia

• Abrupt onset of fever, chills, and dyspnea.

• Rust-colored sputum or hemoptysis.

• Dullness to percussion; inspiratory crackles.

• Dense lobar or segmental infiltrates on X-ray

CURB-65 Scoring System for Pneumonia

• Confusion

• Uremia (BUN > 20)

• Resp Rate > 30

• Blood Pressure (Low)

• Age ≥ 65

Score < 2: Outpatient care | Score 2: General Ward | Score > 3: ICU Consideration

Recovery and Monitoring of Pneumonia

• Initial Response: Constitutional symptoms (fever, malaise) should improve in the first 2 days.

• Cure: Complete resolution usually takes 5-7 days for mild/moderate CAP.

• De-escalation: Narrow antibiotic therapy once culture results are available to reduce toxicity and resistance.

• Discontinuation: Patient should be afebrile for 48-72h with stable vital signs