Nasal provocation test: how to maximize its clinical use?
Nasal provocation test: how to maximize its clinical use?
Nasal provocation test: how to maximize its clinical use?
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Asian Pac J Allergy Immunol 2010;28:225-31Figure 2. Intranasal areanasi and middle meatus.<strong>use</strong>d for <strong>provocation</strong> <strong>test</strong>ing , i.e., anterior end of inferior turbinate, aggeragger nasi area when compared <strong>to</strong> the inferiorturbinate or nasal septum 24 . However, due <strong>to</strong> theease of placing discs on the inferior turbinate, thismethod is recommended by the author. On theother hand, physicians unfamiliar with forcepshandling could make iatrogenic injury <strong>to</strong> theintranasal structures. Due <strong>to</strong> these shortcomings,some researchers prefer other delivery methods.Bottle droppers and micropipette methods areeasy <strong>to</strong> <strong>use</strong> delivery devices. Nonetheless, theymay have some disadvantages since the area inthe nose where the allergen has been applied isnot seen. Moreover, allergen could be aspiratedin<strong>to</strong> the larynx, inducing cough, laryngealirritation, edema or bronchospasm 18 .A better method of delivery could be by usinghand-operated nasal spray. With the spraymethod, a reasonable contact area would be <strong>to</strong> theanterior part of nasal cavities. Beca<strong>use</strong> of ease of<strong>use</strong> and the predictability of the amount ofallergen administered, most of research centers inEurope recommend this method as a standarddelivery system 23 . A<strong>to</strong>mizers also generate largerparticles which help avoiding aspiration ofallergens in<strong>to</strong> the lower airways.Allergen dosageSome investiga<strong>to</strong>rs <strong>use</strong> titration doses butsome <strong>use</strong> one single concentration of allergen forroutine <strong>clinical</strong> NPT 7 . For titration NPT, thelowest allergen concentration should be startedfrom 1:10,000 <strong>to</strong> 1:5,000 w/vol or 50 allergenunit (AU)/ml or 50-100 protein nitrogen unit(PNU) 7,25 . If the initial concentration does notinduce any symp<strong>to</strong>m or <strong>clinical</strong> signs, then thenext concentration is increased by a 3-foldincrement, e.g. 1:10,000, 1: 3,000, 1: 1,000 26 .It should be noted that such recommendeddoses have been applied <strong>to</strong> European subjects.According <strong>to</strong> a study by Roongapinun et al.performed in 44 Thai patients with perennialallergic rhinitis, significant changes in <strong>to</strong>tal nasalsymp<strong>to</strong>m score (TNSS) and nasal airwayresistance (NAR) were observed at theconcentration of500-1,000 AU/ml 27 .The dosage of allergen will also depend on thedelivery technique. For the paper disc technique,Okuda <strong>use</strong>d 3mm diameter disc soaked with 5-500 ug ho<strong>use</strong> dust extract 24 . Schumacher et al.<strong>use</strong>d 4 mm disc with 10 µl dose 28 . We havemodified the Okuda-paper disc method by using5mm disc with a 0.01 ml dose 29 . For the a<strong>to</strong>mizerdosimeter,0.1 ml of allergen per spray is <strong>use</strong>d.The <strong>test</strong> solution is applied in<strong>to</strong> the nose bypointing the device upwards and laterally <strong>to</strong>deposit allergen solution on the middle andinferior turbinates, while avoiding sprayingdirectly <strong>to</strong> the back of the nose 7 . EvaluationFour cardinal symp<strong>to</strong>ms of allergic rhinitis areassessed before and after instillation of allergenextract in<strong>to</strong> the nasal cavity. They are itching,sneezing, rhinorrhea and nasal obstruction.228Downloaded from http://apjai.digitaljournals.org. For personal <strong>use</strong> only. No other <strong>use</strong>s without permission.