Asthma

Bronch ial A sthm a Sylvia Esevwe & Martin Muriithi

Defin ition of As thma 

Chronic reversible inflammatory obstructive lung d’se xcterised by increased response to stimuli

Ep id emiology 

Repo rt edl y Unc omm on Co ndit io n – Afric a  

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Higher preval enc e Western Wor ld 

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Before 19 90 p reval ence 0.1 -4% Few st ud ies of preva lence 5-1 0%

Pre va lenc e In creasing Af ri ca And Western Count ri es

Epidem. Contd    

Onset at any age bt mo in children 30% symptomatic by 1 yr of age 80-90% symptomatic by 4-5yrs of age Sex preponderance [M:F] =1:1 in older children =1:2 in adults =2:1 in infants

Epidemiology Within Africa 

Geogra phica l Var ia tions 

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Ur ban reg io ns -hi gher pr eval en ce Rar e – Ru ra l

Kenya 

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Ru ral pr ev al en ce 5- 13% Ur ban pr eval en ce 20%

Hypotheses -- Increase Asthma 

Hygiene Hy pothe sis 

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Ex posur e to infec tion ea rli er in lif e— prot ecti ve a ga inst Ast hma

Para sit ic Infec tio n Western Die t and Obe sit y Poll uti on  

Not f ound to caus e As th ma May inc rease sympt oms

Ris k Fa ct or s          

Poverty Black race Maternal smoking Maternal age <20yrs at t.o.b. Birth wt <2.5 kg Familial/genetic Hx of atopy Frequent RTI in childhood esp viral Bronchial hyperactivity Exposure to allergen at infancy

Et iolog y        

Mult ifa ctori al Immunological Infection Endocrine Psychological Pharmacologic Environmental Occupational

Ty pes 

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Allergic/Extrinsic young child with H/O asthma/allergic d’se in family Idiosyncratic/Intrinsic no H/O asthma nor allergy, mostly adults

Classifica tion 

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Mild intermittent symptoms < x2 a wk, normal FEV1 Mild persistent symptoms > x2 a wk, normal FEV1 Moderate persistent daily symptoms, FEV1 60-80% of predicted values Severe persistent continuous symptoms, FEV1 < 60% of predicted, limitation of physical activity

Pathop hysiolog y Mucosal Inflammation  Bronchial Hyper-responsiveness 

Patho.cont’d 

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Early phase Inflamm med > airway smooth mm contraction > ^ cap perm, mucous secretion & ^ in neuronal reflexes All > bronchoconstriction responsive 2 bronchodilators 1st 6 hrs Late phase Inflamm cells recruitment =eosinophils >ECP & MBP > a’way desquamation >nerve ending xposure > hyper responsiveness Persistence of inflamm effects long after inflamm process clears 2 Phases >; = ^ a’way resist n obstruction = lung hyper inflation = V/Q mismatch = ^ dead space ventilation = decreased compliance & ^ work of breathing

Chronic Inflammatory Disorder Increased Lymphyocytes, Eosinophils and Mast cells, Neutrophils  Mucosal Edema/Inflammation  Increased Mucous Production  Assoc Bronchial Hyper-responsiveness  Triggered by Allergen or Other Exposures 

Pathophysiology Of Asthma

Allergen Triggers   

Dust mit es Molds Cockroa ches 

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Tree/g ra ss p ollens 

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Urba n sett in gs + Africa

Ber mu da gra ss, Ki ku yu gra ss, corn pol len , flower polle n

Cat & Dog D ander Feat hers Thr eshi ng product s Bat gu an o

Other Exposures/Triggers 

Smoke 

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To ba cco smo ke rs in the home Co oki ng in Un ven ti lat ed huts

Kerosene fu el use Occupa tiona l As thma 

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Ov er 200 ag en ts de scri bed Po or ven til at ion in the wo rkp la ce

Clin ical P res enta tion 

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In ter mit tent reve rsib le obst ru ct iv e symp toms Ch est tigh tness Wh ee zin g Co ugh (dry > pr oductive ) Po st- tussi ve eme sis Wo rse at nig ht Asso ciat ion wit h Tr igge rs

Phys ic al Ex am F in din gs          

Wh ee zin g If seve re  May b e n o wheezi ng Pr olonge d Exp ira to ry Ph ase Cr ack les / Crepi tat ions Pu ls us pa rado xu s Ta chy pn oea Ta chy car di a Hy per inflat io n Ot her occas io nal findin gs Normal Exam If not hav in g symp toms

Physical Exam Findings

St atus As thma tic us  

Severe asthma unresponsive 2 bronchodilators Xstics; =cyanosis =severe dyspnoea =systolic hptn =pulsus paradoxus =silent chest =PaO2 <60mmHg =PaCO2 >50mmHg =tachycardia

CXR Findings 

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Normal with Mild Increase in Perihilar markings Hyperinflation during an exacerbation 

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Secondary to obstructive disease

Patchy Infiltrates Segmental Atelectasis 

Clears after therapy (unlike infiltrates of PNA)

Diagnosis 

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Sus pic io n on his toric al and cli nic al gr ounds Fami ly hi st ory Ot he r At opic Di sease Respo nse t o Bronc hodi la tors

Differential Diagnosis  Al l

Tha t Wh eezes Is Not As thm a

 Not

every Asth mati c wheeze s

Differential Diagnosis 

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URT I  Ca us ed b y V ir us/ Meas les  Not responsi ve t o Bronchodi lat ors Ingest ed For eign Body Cong enit al Hea rt Di seas e/Ca rd ia c Fa il ur e Tracheo esop ha gea l Fist ul a, V asc ula r Ri ng Helmi nt he s Inf ecti on

Differential Diagnosis 

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Bronchi oli ti s  Most Commonl y RS V  Not a s clea rl y r evers ib le w / Bronchod il at ors  Not a ss oc iated w/ Eo sin ophi li a  Most co mmonl y dur ing t he f ir st 6 mos of lif e  Sea sona l Croup=l aryng otr acheobronchi ti s

Treatment-Avoidance of Triggers 

Allergen Avoidance-Difficult Rural Settings in Africa   

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Foa m i nst ea d of f eather pil lows Pill ow/M att ress Covers Reduc tion of books, st uf fed an ima ls , rugs i n sl eepi ng a rea s Remova l of cats/d ogs Pesti cid es t o d ecrea se ex pos ure t o coc kr oaches

Prophylactic/Anti-Inflammatory Treatment 

Inhaled Steroids 

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Cor ti cos teroid s interf ere wit h Inf la mma tor y p roc ess i n mul ti pl e st eps Mi ni ma l, if a ny, si de effec ts

Singulair/Montelukast  

Leukotr iene a nt agoni st s Ma y be u sed in ove r 1 -2 y/o

Anti-Inflammatory –Others 

Cromolyn (Inhaled)    

Also reduces Ai rw ay Infl amma ti on Mas t cel l st abi li zer Negl igi ble si de eff ect s Ef fec tiv e 

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Equ al Theo phyl li ne But wit h less si de ef fect s

Comp li anc e di ff icul t— 3-4 t ime s/da y

Long Acting ß2 Agonists

Therapeutic/Bronchodilator Adrenergic Agents 

Ep in eph ri ne    

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Inh al ed Br onchod il ators  

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Bin ds to al l 3 recep to rs ( α , ß1, ß2 ) Effect s of α  pe ri ph. Va so co nst rict in o Effect s of ß1  In cre ase He ar t Rat e Effect s of ß2  Bro nch ial Smo oth Mu scl e Rel ax at io n Salme te rol, Al but ero l Bet a Adr ene rg ic Ag oni st s (rel at ivel y sel ect iv e for ß1 ) Ro le of ora l Bet a Ago nist s li mi te d

Terb ut al in e

Therapeutic-Bronchodilator 

Theoph yllin e 

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Met hyl xa nt hin e  Inhi bi ts Act ivi ty of Ph osp hodi es ter ase (h ydr olyze s cAMP an d ad en osi ne recep tor an tag onis t) Side Ef fect s :N/V, A rry thmi as , Sei zu res, De at h Long te rm ef fect s: Lear ning and Beh avi or di so rder s Nar row Ther ap eu tic Win dow --> mar ke d in div id ual var iotio n i n The ophy ll ine cle ar an ce b/w in div id ual s, b/w ag es, & w/ foods and dr ug i nter act io ns Nee d to foll ow leve ls pe rio dica ll y

Inhaled Medications   

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Metered Dose Inhalers (MDI) Dry Powdered Device (DPI) Nebulizer Follow Peak Flow Meter 

Can follow Pea k Fl ow at home

Inhaled Medications-Proper Use 

Without Spacer

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With Sp acer  Ma y Us e Pla st ic Bott le

Treatment—Chronic Asthma  

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Intermittent – No daily medication Mild or Moderate Persistent – AntiInflammatory Severe Persistent – Anti-Inflammatory +++

Treatment of Asthma Exacerbation  Inhaled

 Steroids

 Oxygen

Bronchodilators – oral

CASE #1

Case #2

Case #3

Status Asthmaticus   

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Medical Emergency Requires Immediate Management Often occurs after delay in presentation for Treatment After inadequate treatment (Common in Resource poor settings

Status Asthmaticus 

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Frequent or Continuous Nebulized Albuterol Atrovent/Ipatropium Bromide used in severe Asthma for possible synergy IV Steroids Oxygen Terbutaline SQ (or Epi SQ) Heliox