Upper Respiratory Tract Infections Quiz

Upper Respiratory Tract Infections

• Over 200 virus strains cause upper respiratory tract infections, with rhinoviruses being the most common.
• Viruses, not cold temperatures, cause colds, however, severe exposure leading to hypothermia may increase susceptibility.
• Colds are more common in winter due to cold temperature-induced changes in the respiratory system, decreased immune response, and low humidity.

Normal Defense Mechanisms of the Respiratory System

• The nasal cavity is lined with cells that release mucus containing lysozymes to kill bacteria.
• Nose hairs trap large particles of dust, pollen, and bacteria.
• The paranasal sinuses warm and moisten inspired air.
• The tonsils act as the first line of defense, trapping viruses and bacteria entering through the mouth or nose.

Rhino Sinusitis

• Often caused by the spread of bacteria from the nose to the sinuses.
• In immunocompromised individuals, rhino sinusitis can be caused by fungi like Aspergillus.

Pharyngitis

• Infection of the pharynx (throat).
• Can be caused by viruses such as rhinovirus and coronavirus or bacteria like Group A Streptococcus ("strep throat").

Tonsillitis

• Infection of the tonsils.
• Often occurs when pharyngitis spreads to involve the tonsils.

Laryngitis

• Infection of the larynx (voice box).
• Most commonly caused by viruses, but can also be caused by bacteria like Group A streptococcus, Streptococcus pneumonia or Haemophilus influenzae.

Epiglottitis

• Infection of the epiglottis, often caused by Haemophilus influenzae.
• The vaccine for Haemophilus influenzae type b has significantly decreased the incidence of epiglottitis.

Common Cold Symptoms

• Runny or stuffy nose (rhinorrhea), sore throat, cough, headache, and fatigue.
• Rhino sinusitis can cause facial pain or pressure and changes in voice.
• Tonsillitis causes pain and swelling in the tonsils, making swallowing difficult.
• Laryngitis causes hoarseness and a dry cough.
• Epiglottitis can cause difficulty breathing and is a medical emergency.

Common Cold Diagnosis

• Mostly based on clinical diagnosis (history, symptoms, physical examination).
• Radiographic studies can help assess complications like pneumonia.
• Laboratory studies like rapid viral antigen tests and nasopharyngeal cultures can be helpful for diagnosis and epidemiology.

Pharmacological Treatment - Decongestants

• Indication: Nasal congestion.
• Dosage forms: Oral, topical (drops, spray, inhalers).
• Mechanism of action: Alpha-adrenergic stimulation leading to vasoconstriction of blood vessels in the nasal mucosa, reducing mucosal edema and improving nasal drainage and air circulation.

Decongestant Examples

• Topical: Phenylephrine (Vibrocil), Xylometazoline (Otrivin), Oxymetazoline (Afrin).
• Oral: Phenylephrine (Rhinopro), Pseudoephedrine (Sudophine).

Decongestant Adverse Effects

• CNS: Anxiety, insomnia, nervousness, tension, tremors.
• CVS: Tachycardia, increased blood pressure.
• Local: Burning of nasal mucosa (drops and spray), managed by saline irrigation.

Decongestant Use with Caution

• Patients with hypertension, prostatic enlargement, diabetes mellitus, or active hyperthyroidism.

Decongestant Contraindications

• Patients taking monoamine oxidase inhibitors (MAOIs), uncontrolled hypertension, ischemic heart disease, or nonselective beta-blockers.
• Alternatively, saline nasal drops, levomethamphetamine (Vicks Vapor Inhaler), or local decongestants can be used.

Pharmacological Treatment - Antihistamines

• Mechanism of action: H1-receptor blockers, but primarily used for their anticholinergic effects.
• Indication: Rhinorrhea, sneezing, nonproductive cough.
• First-generation antihistamines (chlorpheniramine, diphenhydramine) are suitable for symptom management.
• Second-generation antihistamines (loratadine, fexofenadine, cetirizine) have limited anticholinergic activity.

Antihistamine Side Effects

• Anticholinergic: Dry mouth, difficulty urinating, constipation, blurred vision, irritability, dizziness.
• CNS: Sedation, dizziness, tinnitus, incoordination, fatigue, euphoria, nervousness, tremors.
• GIT: Loss of appetite, nausea, vomiting, epigastric distress (reduced by taking the drug with meals).

Antihistamine Contraindications

• Patients taking MAOIs, those with narrow-angle glaucoma or prostatic hypertrophy.
• Avoid combining with alcohol or other CNS depressants.

Pharmacological Treatment - Analgesics

• Indication: Sore throat, myalgia, headache.
• Acetaminophen, ibuprofen, naproxen.
• Acetaminophen is generally preferred, especially for patients with aspirin allergy or active ulcers.

Complementary Therapy

• Zinc: May reduce the risk of catching a cold if taken for more than 5 days in a season. May help reduce the severity and duration of cold symptoms if taken within 24-48 hours of feeling sick.
• Vitamin C: Does not prevent colds, but regular use may result in slightly shorter and milder colds.

Important Counseling Points

• Topical decongestants should be used for only 3-5 days to prevent rebound congestion: Receptor desensitization and damage to the nasal mucosa can occur.
• Selective alpha1 agonists (phenylephrine) are less likely to induce mucosal damage.
• To manage rhinitis medicamentosa, slowly withdraw topical decongestants and use saline nasal drops, Vicks Vapor Inhaler, or oral decongestants if tolerated.
• With antihistamines, avoid driving or operating heavy machinery until the patient is aware of how they will react, especially if administered at night.

Common Cold in Pediatrics

• The FDA does not recommend OTC medications for cough and cold symptoms in children under 2 years due to the risk of serious and potentially life-threatening side effects.
• Home remedies like rest and hydration can help ease symptoms.

Key Facts

• Rhinoviruses are the most common cause of upper respiratory tract infections.
• Hypothermia can increase the risk of developing a cold.
• Colds are more common in winter due to environmental factors.
• The tonsils are the body’s first line of defense against viruses and bacteria entering through the mouth and nose.
• Epiglottitis is a potential medical emergency.
• Acetaminophen is generally preferred for treating the common cold symptoms.
• Topical decongestants should be used cautiously and for a limited time to avoid rebound congestion.
• OTC medications for cough and cold symptoms are not recommended for children under 2 years old.

Test your knowledge on upper respiratory tract infections, including their causes, defense mechanisms of the respiratory system, and specific conditions like rhino sinusitis. Understand the role of viruses and the body's defenses in protecting against infections.