severity of cough categories
1) Acute: < 3 wks
2) subacute: 3-8 wks
3) chronic: > 8 wks
pathophysiology of cough
1) stimulate receptors on pharynx, larynx, trachea, bifurcation of large bronchi
- chemical stimulation: cigarette smoke, strong odours (perfume/scent), noxious fumes
- mechanical stimulation: foreign particles, sputum
2) relay signal to cough centre in medulla
- afferent pathway for vagus nerve
3) activate muscles in diaphragm, chest wall, abdomen
4) contraction of muscles + sudden opening of glottis
- rapid expulsion of air
aetiology of acute cough
1) viral URTI
2) acute bronchitis
3) exacerbation of asthma
4) exacerbation of COPD: increase mucous
5) exacerbation of CHF: pulmonary oedema
6) pneumonia
7) foreign body aspiration
aetiology of subacute cough
1) post-infectious cough
2) exacerbation of underling disease (e.g. asthma)
aetiology of chronic cough
1) upper airway cough syndrome (UACS)/post nasal drip
2) asthma: cough-variant asthma
3) COPD: increase mucous
4) GERD: acid go up to larynx/trachea
5) drugs: ACEi (dry cough), BB (narrowing of airway)
6) pulmonary malignancies: mass -> obstruction
7) tb
types of cough
1) productive cough
- function: remove secretion from lower respiratory tract
- S&S: ‘wet’/chesty, clear/purulent/malodourless sputum
- types of sputum produced
. bronchitis: clear
. common cold: yellow/green (part of healing process)
. bacterial: mucupurulent
. anaerobic bacteria: malodourless
2) productive cough
- no function
- no sputum produced
- S&S: dry, tight, tickly
when to refer for cough
1) concurrent cardiopulmonary chronic disease (asthma, COPD, CHF), GERD
- treat these before cough
2) difficulty breathing: SOB, blue tinge on lips/palm, increase/decrease respiratory rate
- assess for hypoxia (urgent referral)
3) chest pain
4) hemoptysis
- rust: pneumonia
- pink: CHF
- dark red: carcinoma
5) unintentional weight loss
6) drenched in night sweat
7) fever > 37.5, cough > 7 days
8) thick yellow/green sputum, pus-like secretion
- sign of bacterial infection
9) drug induced
10) worsen/new symptoms during self treatment
11) inhalation of foreign particles
12) barking cough (coup)
- common in children
assessment of cough
1) assess signs and symptoms
- onset & duration
- periodicity: UACS worse in morning/night, chronic bronchitis worse night
- recurrence: chronic bronchitis (esp if smoke), asthma (child with history of asthma/rhinitis/eczema)
- characteristics: presence of sputum, sputum colour, sputum nature (thin/frothy = HF, thick & mucoid - yellow = asthma, foul-smelling = lung abscess/necrosis cuz of microbial infection)
- associated symptoms (Systemic RF)
- aggravating/relieving factors
2) gather patient social/medical history
- age: children (Coup), < 40 (asthma), old smoker (chronic bronchitis, carcinoma)
- smoking
- drugs
differential diagnosis to eliminate common cold induced cough
1) UACS/post nasal drip
2) acute bronchitis: dyspnoea
3) coup
- parainfluenza virus
- eliminate in children 1-2 yo
- non-specific respiratory symptoms: rhinorrhea, sore throat, cough
- SS: barking cough, breathlessness, struggle to breathe between episodes, low grade fever (but can up to 40)
- symptoms worsen at night
- resolve within 48 hrs, can last 2 wks, if not resolved within 48 hrs then medical intervention
4) chronic bronchitis
5) asthma: cough, wheezing, chest tightness, SOB
6) community acquired pneumonia
7) drug induced
8) less likely causes for cough at community pharmacy: HF, tb, lung tumour, GERD
non pharmacotherapy for cough
1) humidification
- increase air moisture content = soothe irritated airways
- demulcent: sooth irritated airways by forming protective film over mucous membrane
2) hydration
- secretion less viscous, easier to expel
- not for LRTI, CHF, renal failure, conditions that worsen from overhydration
3) avoid irritants
4) honey
- soothing effect
- not for kids < 1 yo (risk for botulism, toxin that attacks body nerves)
pharmacotherapy for cough - antitussives uses
non productive cough
pharmacotherapy for cough - antitussives: centrally acting agents - codeine
- MOA: increase cough threshold, suppress cough reflex through central direct action on cough centre in medulla
- onset: 30-60 mins (oral)
- SE: CNS (drowsiness, sedation), GIT (N/V, constipation), urinary retention, respiratory depression
- precaution:
. no CNS depressants
. no proserotogenic drugs (increase risk of serotonin syndrome: agitation, hallucination, tachycardia)
. no concurrent CYP2D6 inhibitor use (cannot convert to active drug, reduce efficacy)
. elderly - CI: concurrent/within 2 wks use of MAOi (increase risk of serotonin syndrome)
- regulations to prevent abuse: limit 240ml/patient, no selling to same patient within 4 days, record sales, no public display, patient counselling
pharmacotherapy for cough - antitussives: centrally acting agents - dextromethorphan
- non-opioid, no analgesic
- MOA: act centrally on cough centre, increase cough threshold
- onset: 15-30 mins (oral)
- SE: CNS (drowsiness, sedation), GIT (N/V, constipation, stomach discomfort)
- first line cuz wider margin of safety + lesser potential for abuse
- precaution:
. no CNS depressant
. no proserotogenic drug
. no CYP2D6 inhibitor - CI: concurrent/within 2 wks use of MAOi
pharmacotherapy for cough - antitussives: centrally acting agents - philcodeine
- derivative of codeine
- mild sedative effect, little/no analgesic/euphoria
- MOA: suppress cough reflex through direct central action
- SE: N/V, gastric disturbances, dizziness, constipation
- precaution: no CNS depressant
- CI: no concurrent/within 2 wks use of MAOi
- limited potential for abuse
pharmacotherapy for cough - antitussives: H1 antagonist - diphenhydramine
- sedative & anticholinergic
- combination for post nasal drip
- single agent for motion sickness, itch, N/V, allergies but not 1st line for cough cuz sedative
- MOA: direct acting on medulla for increase cough threshold
- onset: 15 mins (oral)
- precaution: not for CNS depressants
- SE: N/V, drowsiness, N/V, constipation, dry mouth, urinary retention, blurred vision
- precaution:
1) no CNS depressants
2) no anticholinergic agent/sedatives
3) not for patients with closed angle glaucoma, increased ocular pressure, prostate hypertrophy, stenosing peptic ulcer, bladder neck obstruction, hyperthyroidism, HTN, heart disease
4) elderly
pharmacotherapy for cough - antitussives - others
1) menthol lozenges (menthol + camphor)
- cough suppressive
- stimulate nerve ending on nose & mucosa lining, local anesthetic effect
- no use > 3 days, no heat/microwave
- not for children < 2 yo
pharmacotherapy for cough - expectorant - guaifenesin
- natural product
- MOA: increase respiratory secretion, increase sputum volume, decrease sputum viscosity (easier to remove)
- onset: 30 mins
- CI
1) known sensitivity to guaifenesin
2) not for chronic cough associated with LRTI - hydration to cough out phlegm easier
mucolytics
- MOA: break down phlegm, easier to remove
- N-acetylcysteine/carbocisteine: depolarise mucopolysaccharide by hydrolysing disulfide bond in mucoproteins
- bromhexine/ambroxol: depolarise mucopolysaccharide by liberating lysozymes, increase mucous clearance, decrease sputum surface tension (Easier to remove)
- precaution
1) respiratory obstruction: not for children < 2 yo
2) gastric lining irritation: not for PUD
3) bronchospasm: not for bronchi asthma - SE
1) N-acetylcysteine: N/V, stomach discomfort, D, headache
2) carbocisteine: GI haemorrhage, vomiting
3) bromhexine: D, dizziness, indigestion, N, sweating, skin rash, itch
4) ambroxol: N/V, D, C, dry mouth, rash, itch
special population + monitoring parameters (normal)
. pregnancy & lactation
- antitussive choice: dextromethorphan (no alcohol)
- expectorant choice: guaifenesin (no alcohol)
- pregnant: lowest dose lowest duration
. monitoring
- refer if no improvement within 7 days
