Respiratory Tract Infections and the Common Cold

Respiratory Tract Infections

• The respiratory tract is susceptible to various infectious diseases.
• Infections can affect the upper or lower respiratory tract, or both.
• Symptoms vary depending on the structure affected, severity of illness, and patient's age and general health.
• Viruses commonly cause respiratory infections, which can increase the risk of secondary bacterial infections.

The Common Cold

• The common cold causes a viral infection in the upper respiratory tract and the most common of respiratory tract infections (URTI/URI)
• Rhinoviruses are the primary agents involved with other viruses including parainfluenza, respiratory syncytial virus (RSV), and coronavirus.
• Transmission occurs rapidly between individuals, primarily via touch and aerosolization, particularly among school-age and daycare children.
• The illness lasts approximately 7 days, with a 2 day incubation period.

Clinical Manifestations of the Common Cold

• Clinical manifestations include congestion and drainage of the nasopharynx and nasal passages which can also cause tearing of the eyes - also referred to as rhinitis.
• Secretions are typically clear and watery.
• Redness and swelling of the mucous membranes of the upper respiratory tract.
• Postnasal drip can irritate the pharynx and larynx, which causes sore throat, hoarseness, and cough.
• Additional symptoms include headache, malaise, chills, fever, fatigue, and anorexia.

Treatment of the Common Cold

• A self-limiting illness in otherwise healthy individuals.
• Treatment involves rest and symptom management (antipyretic drugs).
• Antihistamines can dry nasal secretions but do not shorten the length of the infection.
• Decongestants constrict blood vessels in the nasal mucosa which is reducing swelling and relieving congestion.
• Maintaining fluid and electrolyte balance is important to avoid dehydration.

Rhinosinusitis

• Rhinosinusitis is the inflammation of the nasal sinuses which are cavities lined with mucosa and cilia.
• It is often associated with a viral upper respiratory tract infection.
• It is often acute viral, bacterial or mixed.
• Symptoms are similar to the common cold, with facial/nasal pain or pressure being commonly reported.
• Treatment involves reducing the cause with medications and symptom management, including antibiotics, rest decongestants

Pneumonias

• Pneumonia presents as inflammation of the lung's parenchymal structures, specifically affecting the alveoli and bronchioles.
• It is the 8th leading cause of death in the US, often from infectious diseases.
• Etiology varies, including infectious and non-infectious agents.
• Inhalation of irritating fumes or aspiration of gastric contents may result in pneumonia.
• Aspiration refers to breathing in a foreign object, which can include stomach contents.

Etiology and Classification of Pneumonias

• Pneumonias is classified based on the circumstances of acquisition, including hospital acquired or community acquired.
• It is categorized by affected airway areas like lobar pneumonia or bronchopneumonia.
• Pneumonias are categorized by the source of the infectious agent including typical (bacterial) or atypical (mycoplasm bacteria or viral).

Community-Acquired Pneumonia

• Community-acquired pneumonia is defined as an infection that starts outside the hospital or is diagnosed within 48 hours of hospital admission.
• It affects those who haven't resided in a long-term care facility for at least 14 days before admission.
• The pneumonia can be bacterial or viral.
• Diagnosis involves history, physical examination, and chest x-rays.
• Treatment includes antibiotics and symptom support, and involves hospitalization, especially for the elderly or medically fragile.

Hospital-Acquired Pneumonia and Pneumonia in Immunocompromised People

• Hospital acquired pneumonia is a lower respiratory tract infection not present or incubating upon hospital admission.
• Hospital acquired infections are often bacterial, antibiotic resistant, and challenging to treat.
• Pneumonia in immunocompromised people occurs when the patient presents with weakened immune systems due to underlying diseases, bone marrow or organ transplants, corticosteroid use, or immunosuppressant drugs.

Acute Bacterial (Typical) Pneumonia

• Acute bacterial pneumonia significantly contributes to mortality in the elderly and people with comorbidities.
• The body's primary defenses effectively maintains the lower airways sterile while we inhale infectious microorganisms all the time.
• Upper respiratory tract infections can compromise these defenses and increased risk of pneumonia.

Clinical Risk Factors in Acute Bacterial Pneumonia

• Patients with critical or chronic illnesses often have airway epithelial cells prone to bacterial adherence.
• Other risk factors, include antibiotic use altering the natural bacterial flora, diabetes, smoking, COPD, and viral infections.
• Pneumococcal Pneumonia and Legionnaire's Disease, are two main types, categorized by their etiological agent.

Pneumococcal Pneumonia

• The most common type of bacterial pneumonia.
• This pneumonia structural makeup delays phagocytic digestion, leading to rapid spread.
• Symptoms include fever, malaise, productive cough with sputum color changes to red, brown, or purulent, crackles, pleuritic pain, and anorexia.

Treatment and Pleuritic Pain of Pneumococcal Pneumonia

• Treatment is specific to antibiotic effective to the strain and symptom management.
• Preventative immunization is recommended for those ≥65 years or medically fragile.
• Pleuritic pain is chest pain, often tightness, worsened by coughing, deep breathing, and movement.

Legionnaire Disease

• Legionnaire Disease presents as bronchopneumonia often transmitted via aerosolized droplets from water contaminated with pathogen.
• First documented at an American Legion Convention in 1976.
• The highest risk are smokers, medically fragile, and immunosuppressed individuals.

Signs, Symptoms, and Treatment of Legionnaire Disease

• Signs and symptoms include fatigue, weakness, lethargy, fever, dry cough, CNS disturbances, GI disturbances, and joint pain.
• Treatment is specific to antibiotic effective to the strain and consists of symptom management.

Primary Atypical Pneumonia

• The causes of primary atypical pneumonia are either mycoplasm bacteria or viruses.
• Characterized by patchy lung involvement, affecting the alveolar septum and pulmonary interstitium which is the space between blood vessels and alveoli.
• Patients have damaged epithelium that makes them susceptible to secondary lung infections.
• Symptoms are typically mild and present as a dry cough

Severe Acute Respiratory Syndrome (SARS)

• SARS is a respiratory illness that stems from a coronavirus.
• Symptoms include fever, chills, malaise, headache, muscle aches, nonproductive cough, dyspnea, and diarrhea.
• Primarily spread person to person via respiratory droplets.
• While severe, mortality primarily affects the elderly and medically fragile.

Lung Cancer

• 80% of lung cancer incidents are linked to cigarette smoking.
• Despite declining smoking rates and lung cancer cases, teenage smoking and vaping are rising, potentially reversing progress.
• Other risk factors include exposure to asbestos and other inhaled irritants.
• Symptoms vary based on cancer spread and treatment approach.

Clinical Manifestation of Lung Cancer

• Anorexia, weight loss, and fatigue
• Chronic cough, shortness of breath, wheezing, and hemoptysis
• The origin of pain depends on the pleural tissue affected by the tumor.
• Pleural effusion may result in atelectasis.
• Compromised oxygen saturation, pallor, and cyanosis.

Anatomy Reminders for Pediatric Respiratory Disorders

• Intercostal muscles are not fully developed in infants and the patients rely mainly on the diaphragm.
• Their lungs and chest are highly compliant.
• Accessory muscle use signifies severe distress due to rapid fatigue in pediatric patients.
• Narrow airways in pediatrics are prone to obstruction from foreign bodies or mucus.
• Infants large occiput can obstruct the airway, so airway management is critical.

Manifestations of Respiratory Distress in Infants and Small Children

• Grunting which is an audible sound during exhalation is an attempt to increase PEEP and extend gas exchange.
• Positive end-expiratory pressure (PEEP) refers to pressure sustaining airway patency at cycle's end.
• Retractions present as an inward movement of the accessory respiratory muscles and indicate distress or fatigue in intercostals, supraclavicular, scalene, substernal, tracheal notch, and abdomen.
• Nasal flaring is where the nares enlarge in an attempt to decrease resistance for nasal breathers.

Additional Manifestations of Respiratory Distress in Infants and Small Children

• Stridor is a high pitched audible wheeze/squeal due to upper airway obstruction.
• Wheezing is an audible sound heard during auscultation that indicates narrowing of the distal airways
• Other signs include lethargy, head bobbing, tripod positioning, drooling, pallor, and cyanosis.
• Tachypnea, dyspnea, and orthopnea.

Croup

• Croup, or acute laryngotracheobronchitis, stems from a viral infection of larynx, trachea, and bronchi.
• Typical onset is between 3 months and 5 years old.
• Inflammation from the virus can lead to swelling and airway blockage.
• Croup often starts as a common cold with symptoms that progress to include a stridor and dyspnea.
• Classic sign is a distinct "barking cough," often described as "seal-like".

Symptom Management and Treatment of Croup

• Symptoms improve in moist or cool air.
• Airway obstruction can severely worsen the condition and aggressive manipulation can lead to cardiopulmonary arrest.
• In prehospital settings, severe croup is treated with nebulized epinephrine and dexamethasone.

Spasmodic and Bacterial Croup

• Spasmodic croup are thought to be allergic with presentation similar to viral croup but allergic in origin (afebrile).
• Spasmodic episodes happen at night and last several hours.
• High humidification or cold air effectively lessons irritation
• Bacterial croup is very rare, similar in presentation of viral croup buts symptoms and severity may progress more rapidly and can typically be treated with antibiotics.

Epiglottitis

• The causes is an acute infection of the epiglottis, which are most often stems from bacterial.
• Inflammatory edema affects the supraglottic area (epiglottis and pharynx).
• Quick onset of symptoms can cause fatal airway obstruction and asphyxia within hours.
• Asphyxia causes suffocation and occurs when the patient passes out from hypoxia.

Clinical Presentation of Epiglottitis

• Patients show pallor, lethargy, maintain a distinct position where they sit up, with mouth open and chin thrust forward.
• Difficulty swallowing leads to drooling and muffled speech.
• Moderate to severe dyspnea and is often accompanied by a fever.
• Inclusions are stridor, nasal flaring, and inspiratory retractions.

Acute Bronchiolitis

• RSV causes is a viral infection of the lower airway and usually affects children younger than 2 years old, specifically 3-6 months old.
• It creates inflammatory obstruction and necrosis which affects the endothelial cells lining the airway.
• In infants, condition starts with a mild upper respiratory infection, then progresses gradually to respiratory distress, cough, irritability, and wheezing.