Family Medicine JC129: Upper Respiratory Tract Infections Flashcards
Upper respiratory tract
Nostrils —> Sinuses —> Nasopharynx —> Oropharynx —> Laryngopharynx —> Epiglottis —> Vocal cord —> Upper part of airway
ALL can be site of infection
Common respiratory problems in HK
- URI
- Acute bronchitis
- Allergic rhinitis
Upper Respiratory Tract Infections (URTI)
- NOT all cough, runny nose and sore throat are URTIs
To establish URTI:
- Features of **Acute infection + **URT symptoms
***Different types of URTIs
1. Coryza (common cold) (most common)
2. Influenza
3. Tonsillitis (viral / bacterial)
4. Pharyngitis (viral / bacterial)
5. Acute laryngitis (viral / bacterial)
6. Others
Symptoms for diagnosis:
***記: URT symptoms:
1. Cough / Sputum
2. Runny nose / sneeze
3. Nasal congestion
4. Sore throat
5. Hoarseness
Systemic symptoms of infection:
1. Fever
2. Chills
3. Malaise
4. LOA
5. N+V
(6. Dyspepsia, Abdominal pain)
URTI vs LRTI
Acute URI
- **Coryzal (Nasal) symptoms
- Fever
- **Sore throat
1. Coryza (common cold) (most common)
2. Influenza
3. Tonsillitis (viral / bacterial)
4. Pharyngitis (viral / bacterial)
5. Acute laryngitis (viral / bacterial)
6. Others
LRT illness
- **Respiratory distress
- **Lower chest signs (crepitations, wheeze, rhonchi)
- Tachypnea
- Increased work of breathing
- Fever
1. ***Acute bronchiolitis (wheeze (∵ inflammatory exudates in airway) +/- crepitations, usually due to RSV, HMPV (Human metapneumovirus))
2. Pneumonia (viral / bacterial)
3. Asthma
- Cough / Sputum
NOT all cough and phlegm are due to URIs
Cough / Sputum in URI:
- Acute irritating cough
- **Scanty, **white / yellow sputum
- **Postnasal drip / sore throat
- **Present throughout daytime and before / after sleeping
- General condition good, no SOB / added sound / chest sign
- Self-limiting, lasting 1-3 weeks
History taking:
1. Nature
- Dry cough
- Sputum: colour
- Course
- Acute / Subacute / Recurrent / Chronic - Emergencies
- **Cyanosis / **Dyspnea / ***Drooling of saliva - Serious
- **Pneumonia
- **TB
- **Cancer
- **CHF (Cardiac cough) - Pitfalls
- Allergic rhinitis
- **Asthma
- **COPD
- **Bronchiectasis
- **GERD
- ***Drugs (e.g. ACE inhibitor induced cough)
- Malignant pleural effusion
- Runny nose + 3. Nasal congestion
NOT all runny nose are due to URIs e.g. Allergic rhinitis
Nasal symptoms in URI:
- Acute onset
- **Copious + **Clear watery discharge
- Sneezing ++, relatively **little itchiness
- **Little diurnal variation
- Self-limiting, lasting 3-5 days (subside earlier than cough)
Physical examination
- Nasal speculum to examine anterior nose (usually not needed): Nasal mucosa congested with overlying clear discharge (vs Allergic rhinitis: Edematous + Bulky nasal mucosa)
- Ear: look for Otitis media (tympanic membrane congested / fluid level behind)
Runny nose:
- common cause of snoring + anosmia
- complications: **Otitis media, **Sinusitis
History taking:
1. Nature and Course
- Yellow nasal discharge =/= Bacteria!!!
- Serious
- ***NPC (mixed with blood) - Pitfalls
- **Allergic rhinitis
- **Polyps
- Foreign body in nose
- ***Sinusitis
- Sore throat
- **>90% acute sore throat due to **Viral URIs
- Enlarged tonsil are normal in children (as long as symmetrical + no exudates)
- Exudates can mean Viral / Bacterial!!! (although mostly ***bacterial)
History taking:
1. Emergency
- ***Acute epiglottitis (drooling of saliva)
- Serious
- **Bacterial tonsillitis
- **Peritonsillar abscess (Quinsy)
- TB
- Lymphoma - Pitfalls
- Postnasal drip
- Irritation
- Foreign body ingestion
- ***Infectious mononucleosis
***CENTOR criteria for sore throat
Estimate probability that pharyngitis is Streptococcal (distinguish from Viral)
- Bacterial if not treated with antibiotics can present with complications
4 criteria (1 point for each positive criterion):
(記: Fever, Exudates, Lymphadenopathy, Absence of cough)
1. History of fever
2. Tonsillar exudates
3. Tender anterior cervical lymphadenopathy
4. Absence of cough
Modified CENTOR criteria (add patient’s age to criteria)
5. Age <15 (+ 1 point)
6. Age >44 (- 1 point)
Score range: -1 to 5
- -1 to 1: No antibiotic / throat culture necessary
- 2/3: Consider **rapid strept testing / culture + Treat with antibiotic if positive result
- 4/5: Consider **rapid strept testing / culture + Treat with antibiotic if positive result
- Hoarseness
- Indicate pathology in Larynx
- If ***Acute: most likely Viral URI
- If Chronic: consider other DDx
DDx:
1. ***Vocal cord polyps / nodules
- Serious
- **Carcinoma of larynx
- **Acute epiglottitis (A/E care)
- ***Croup (A/E care) - Pitfalls
- Sputum
- Laryngeal injury / compression
- Trauma from intubation
Disease burden of URI
- Most common infection in human
- Annual incidence from 5-7 in children to 1-2 in elderly
- Rarely lethal
- Significant health + economic burden
—> Doctor consultation
—> Manpower loss
Pathogens of URIs
> 90% Viral:
- Rhinovirus
- Adenovirus
- Influenza
- Parainfluenza
- RSV
- Coronavirus
<10% Bacterial:
- Group A Strept
- Haemophilus influenzae
- Strept pneumoniae
- Moraxella catarrhalis
- Staph aureus
Transmission of Common cold
- Contacts + Droplets
- Maximum viral shedding on Day ***2 and 3 from symptom onset
- Found on hands, cough / sneeze
- Natural infectivity rate 38-88%
- Median incubation ***3 days (1-10)
- ***70-90% infected are symptomatic
- Diagnosis:
—> Clinical
—> Viral culture (rarely needed)
—> Serology ***useless
Investigations of URI
No need for most cases
Unless specific indications:
1. CXR
2. **Sputum / Throat swab for culture (if suspected Strept throat)
3. **Nasal aspirate for culture
4. Blood test
5. Others
Natural course of Simple Viral URTI
Usually within **2 weeks even without treatment
**記: Cough同Hoarseness最耐
- Cough: 2-20 days
- Headache: 1-14 days
- Hoarseness: 2.5-20 days
- Muscle ache: 2-14 days
- Runny nose: 2-14 days
- Sore throat: 2-14.3 days
Management of Simple Viral URI
- Body’s immune system is most effective
- Mean resolution **2-3 days (75% **7 days, cough up to 10 days)
- **Rest + **Adequate fluid + ***Stress reduction are important
- Infection control: Wash hands, Wear masks
- ***Self-limiting: Curative treatment is usually not needed
Symptomatic treatment:
- Not a pill for every illness / symptom
- Evidence-based
- Benefit vs Harm
Systemic symptoms / Sore throat management
- Aspirin
- CI in children / influenza (***Reye’s syndrome) - ***Paracetamol
- proven to be effective and safe - ***NSAID (Ibuprofen)
- more effective but more SE (e.g. gastric upset) - Throat lozenges
- no large-scale quality trials - Steroids
- do more harm than good
***Cough and Sputum management
- NO good evidence for effectiveness of OTC cough medicines
- NOT a must to offer cough medication
- Important to reassure patients on the expected course of cough in simple URI e.g. persist up to ***3 weeks even without treatment
***Cough mixture (may contain >=1):
- Cough suppressant (e.g. Dextromethorphan, Codeine, Pholcodine)
- Expectorant (e.g. Guaifenasin)
- Antihistamine (e.g. Diphenhydramine)
- Decongestant (e.g. Pseudoephedrine, Phenylephrine)
- Mucolytic (e.g. Bromhexine, Acetylcysteine)
- Herb (e.g. Echinacea, Squill)
Cough suppressant
Opioid (NOT recommended)
- Dextromethorphan, Codeine, Pholcodine
- MOA: **Central suppression of non-productive cough
- Uncertain effectiveness for URTIs
- **Not recommended in children
- SE: Sedation, GI disturbance
Non-opioid (Sedating antihistamines)
- Diphenhydramine (Benadryl expectorant), Dexbrompheniramine
- Inconsistent results from RCT
- SE (Anticholinergic): Drowsiness, Blurred vision, Dry mouth, Urinary retention (esp. in BPH patients) etc.
Cough expectorants
MOA:
- Thin the mucus / respiratory secretions —> making it easier to be coughed up
Common preparations (mostly non-sedative):
- Ammonium chloride (e.g. MES (Ammonia and Ipecacuanha))
- Ipecacuanha (e.g. MES)
- ***Guaifenesin (e.g. Robitussin)
- Squill (e.g. Cocillana compound syrup)
- Effectiveness NOT proved by RCT, except some evidence on Guaifenesin
- SE: High dose may cause N+V
Mucolytics
Bromhexine, Acetylcysteine
- NO RCT to prove efficacy in URI
MOA:
- Loosens and thins bronchial secretions by reducing surface tension + viscosity of mucus
SE:
- Dizziness, Headache, GI disturbance etc.
Inhaled / Oral β agonists
- May be effective for prolonged (>1 week) cough in URI, esp. in patients with bronchial hypersensitivity
- SE: **Palpitations, **Tremor etc.
- Seldom necessary
Nasal symptoms management
- Antihistamine
- Sedating, Non-selective e.g. Chlorpheniramine may reduce sneezing / rhinorrhoea —> ***more effective but less selective
- Non-sedating, Selective antihistamines are much less effective - Nasal decongestant
- e.g. Pseudoephedrine, Phenylpropanolamine (PPA), Phenylephrine
- may provide transient relief of nasal obstruction
- SE: common, can be serious, caution in ***HT patients
- Both NO proven efficacy in children and adults for URI
- FDA warning: Avoid both in children ***<2 yo (potential life-threatening SE: convulsions, tachycardia, death)
- ***Topical Ipratropium (Atrovent)
- treatment option for nasal congestion in >6 yo and adults
- expensive - Heated humidified air
- conflicting results
- but benign and possibly beneficial
Coryza novel treatments
- Vitamin C 1-3g
- no benefit if taken at onset of illness - Zinc
- within 2 days of onset
- may shorten illness by 1-3 days
- inconsistent evidence
- cannot prevent illness
- up to 20% have SE: N+V, diarrhoea etc.
Combination preparations for URIs
Antihistamine + Decongestant + Antitussive + Expectorants
- risk of overdosing in children + associated with sudden infant deaths
- Shotgun therapy ↑ SE:
—> Aspirin + PPA
—> Antihistamine overdose from cold medicine + cough mixture
Antibiotics / Steroids
- Antibiotics / Steroids are NOT doing any good for Viral URTI
- SE of drugs
- Antibiotic resistance
Importance of Sleep
Adequate sleep can effectively reduce chance of developing a cold
Influenza
- 3 types of Influenza virus: **A, **B, C
Clinical features:
1. Criteria of Influenza-like illness (ILI): **Fever >= 38oC + Cough / Sore throat
2. **Severe systemic upset
3. ***Generalised myalgia
4. Nasal symptoms (mild than common cold)
- Rapid test not more accurate than Clinical diagnosis
- Most cases are ***self-limiting
Complications:
- ***Pneumonia (5-20% esp. high risk groups)
Influenza vaccination
- Effective in preventing illness, complications, hospitalisation, death
- 2020-21: All available seasonal influenza vaccines are ***Quadrivalent vaccines
- Should be given annually at the ***beginning of peak season (Oct - Nov), expected to cover winter + summer surge
- Effective ***2 weeks post-vaccination (develop sufficient Ab)
- Effectiveness 20-90% (depends on age of recipient)
2 types:
1. Inactivated influenza vaccine (most given IM)
- more widely used
- age 6 months / above
- Live attenuated influenza vaccine (Intranasal)
- one brand available: FluMist
- consider for non-pregnant, non-immunocompromised people 2-49 yo
Priority groups for Flu vaccine
At risk of severe influenza / Transmitting influenza to those at high risk:
1. ***Health care workers
- ***Institutionalised persons
- elderly / disabled in care home - Age >50
- ***People with chronic medical problems
- chronic lung, CVS, renal, metabolic disease, obesity, immunocompromised, children on long term aspirin, people with chronic neurological condition that can compromise respiratory function / self care ability / lead to increased risk of aspiration - ***Children 6 months - 11 yo
- vaccination of primary school student via mobile teams - ***Pregnant women
- CI for live attenuated vaccine -
**Poultry workers / Pig farmers / Pig slaughtering industry personnel
- minimise emergence of **novel influenza virus with pandemic potential
Influenza Drug Treatments
- ***Oseltamivir Oral (Tamiflu)
- ***Zanamivir Inhaled (Relenza)
- Peramivir IV (Rapivab)
- ***Baloxavir marboxil Oral (Xofluza) (Newest drug)
Effect:
- Shorten illness by 1-2 days if given within **48 hours
- **Reduce complications
SE:
- Oseltamivir: N+V
- Zanamivir: Bronchospasm
- Peramivir: Diarrhoea
- Baloxavir marboxil: Unknown yet
Summary
- URI are common and highly infectious
- NOT all URT symptoms are caused by URIs
- NOT all URIs are COVID-19
- Different URIs have different pathogenesis and natural courses
- Curative treatments are limited are usually unnecessary
- Benefit of symptomatic treatments need to be balanced against harm
- Personal hygiene and influenza vaccine very important in prevention esp. Influenza
- Flu anti-viral drugs may be considered in patients with influenza depending on circumstances
