The value of acoustic rhinometry in assessing nasal responses to cat exposure

A Model of Allergic Nasal Congestion in Dogs Sensitized to Ragweed

Background

Acoustic rhinometry is a noninvasive method that uses sound waves to measure dimensions of the nasal cavity.

Methods

In this study, nasal patency was measured by acoustic rhinometry in allergic Beagle dogs sensitized to ragweed allergen. Ragweed (0.03–0.3%) or vehicle were administered intranasally in isoflurane-anesthetized dogs.

Results

The instillation of ragweed caused a dose-related decrease in nasal cavity volume and minimal cross-sectional area (Amin) without adverse systemic effects. Nasal cavity volume and Amin decreased within 30 minutes after instillation of the highest ragweed dose by 35.1 ± 6.0% and 66.4 ± 13.8%, respectively, and persisted for at least 90 minutes. Oral administration of α-adrenergic agonist, d-pseudoephedrine (3 mg/kg), or histamine H1 antagonist chlorpheniramine (10 mg/kg) blocked the ragweed-induced nasal congestion.

Conclusion

These results suggest that the canine model may be used to study upper-airway diseases such as allergic rhinitis and to evaluate the pharmacologic activity of nasal decongestants.

Local and systemic effects of cat allergen nasal provocation

Background

Cat allergen is widely distributed in homes and schools; allergic sensitization is common.

Objective

To develop a model of cat allergen nasal challenge to establish dose–response and time–course characteristics and investigate local and systemic biomarkers of allergic inflammation.

Methods

Nineteen cat‐allergic individuals underwent titrated nasal challenge, range 0.243 to 14.6 μg/mL Fel d1, and matched diluent‐only provocation. Clinical response to 8 h was assessed by symptom scores and peak nasal inspiratory flow (PNIF). Nasal fluid was collected using polyurethane sponges and analysed by ImmunoCAP and multiplex assays. Whole blood flow cytometry for basophil surface CD63, CD107a, and CD203c was carried out at baseline and 6 h post‐challenge.

Results

A dose–response to allergen was seen in symptom scores and PNIF, maximal at 10 000 BU/mL (4.87 μg/mL Fel d1), P < 0.0001 vs. diluent. Nasal fluid tryptase was elevated at 5 min after challenge (P < 0.05 vs. diluent); eotaxin, IL‐4, ‐5, ‐9, and ‐13 were increased at 8 h (P < 0.05 to P < 0.0001 vs. diluent); TSLP was undetectable; IL‐10, IL‐17A, and IL‐33 were unchanged compared to diluent challenge. Nasal fluid IL‐5 and IL‐13 correlated inversely with PNIF after challenge (IL‐5, r = −0.79, P < 0.0001; IL‐13, r = −0.60, P = 0.006). Surface expression of CD63 and CD107a was greater at 6 h than at baseline, both in the presence (both P < 0.05) and absence (CD63, P < 0.01; CD107a, P < 0.05) of in vitro allergen stimulation; no changes were seen on diluent challenge day.

Conclusions

Cat allergen nasal challenge produces local and systemic Th2‐driven inflammatory responses and has potential as a surrogate outcome measure in clinical trials.

Correlation between nasal resistance and different acoustic rhinometry parameters in children and adolescents with and without allergic rhinitis

Acoustic rhinometry and rhinomanometry are important tests used to assess nasal function. The degree to which the parameters of these tests are correlated is yet to be established.

Objective

This paper aimed to study the correlations between nasal resistance (NR) and acoustic rhinometry parameters in children and adolescents with allergic rhinitis and controls.

Method

Twenty patients with allergic rhinitis and 20 controls were enrolled. NR, volumes (V4, V5, V2-5), and minimal cross-sectional areas (MC1, MC2) were measured in three moments: baseline, after induction of nasal obstruction and after topical decongestant administration.

Results

Patients with allergic rhinitis had significant correlation between NR and all volumes (V5: r = -0.60) and with MC2. Among controls, MC1 was the parameter with the strongest correlation with NR at baseline (r = -0.53) and after decongestant administration. In the combined analysis, V5 had the highest correlation coefficients at baseline (r = -0.53), after obstruction (r = -0.58) and after decongestant (r = -0.46).

Conclusions

Our data showed that NR and acoustic rhinometry parameters have negative and significant correlations. Nasal volumes are, in general, better correlated than minimal cross-sectional areas. V5 was the parameter with the highest correlation in the rhinitis group and in the combined analysis.

Correlation between acoustic rhinometry and subjective nasal patency during nasal challenge test in subjects with suspected occupational rhinitis; a prospective controlled study

OBJECTIVES

To assess the correlation between acoustic rhinometry and visual analogue scale endpoints in the context of nasal challenge with occupational agents.

DESIGN

Prospective controlled study.

SETTING

University teaching hospital.

PARTICIPANTS

Sixty-seven subjects with a history of work-related rhinitis and asthma symptoms.

MAIN OUTCOMES MEASURES

Subjects underwent nasal challenge with control and specific agent on consecutive days. Nasal congestive response to challenge was monitored by acoustic rhinometry and visual analogue scale.

RESULTS

Results showed no correlation between visual analogue scale and acoustic rhinometry measurements at baseline on the control (r=-0.13, P=0.3) and active (r=0.14, P=0.2) challenge days. No correlation was found between acoustic rhinometry and visual analogue scale when analysing all measurements obtained at all times after challenge with the control and active agent (control: r=0.09, P=0.04; active: r=0.001, P=0.9). The correlation between acoustic rhinometry and visual analogue scale was good and significant (r=-0.62, P=<0.01) when the analysis was restricted to cases showing a decrease in nasal volume>40% from baseline values.

CONCLUSIONS

We showed that the correlation between acoustic rhinometry and subjective nasal patency was poor on steady conditions. However, a significant correlation was observed in those cases showing a greater nasal congestive response after challenge measured by acoustic rhinometry.

Early and late phase asthmatic response in lower airways of cat-allergic asthmatic patients--a comparison between experimental and environmental allergen challenge

BACKGROUND

Standardized experimental allergen challenges are usually adopted to investigate the effect of allergen exposure on the lower airways. Environmental (natural) allergen challenges are used less often, mainly because of difficulties in standardizing the method, safety reasons and costs. The aim of this study was to investigate the relationship between an experimental and an environmental bronchial challenge. For this reason a natural challenge model was developed.

METHODS

Sixty-two patients with a history of cat allergen-induced symptoms involving the lower airways, positive skin prick test, positive in vitro specific IgE to cat allergen and bronchial hyper-responsiveness were included. All 62 patients underwent an experimental challenge in the laboratory followed by an environmental allergen challenge.

RESULTS

All 62 patients developed an early asthmatic response [>or=20% fall in forced expiratory volume in 1 s (FEV1)] in the experimental challenge and 60% (37/62) during the environmental challenge. A late asthmatic response (>or=15% fall in FEV1 within 3-24 h) was seen in 56% (35/62) of the patients after the experimental challenge. Following the environmental challenge 47% (29/62) of the patients developed a late response. Thirty-four per cent (21/62) of the patients developed a late response in both challenge models and 31% (19/62) did not develop a late response in any model. Thus, there was consistency in 65% (40/62) of the patients in both challenge models.

CONCLUSION

We found consistency in the pattern of response to inhaled allergen between the two challenge models and we believe that experimental bronchial challenge is likely to reflect the development of relevant inflammation in the lower airways after low-dose allergen exposure in the environment.

Efficacy of fexofenadine in the prophylactic control of cat allergen-induced allergic rhinitis

BACKGROUND

To date, it is unknown whether fexofenadine mitigates the worsening of symptoms induced by the cat allergen Felis domesticus allergen 1.

OBJECTIVE

To determine the effects of a single dose of fexofenadine hydrochloride, 180 mg, in preventing and controlling cat allergen-induced allergic rhinitis symptoms using the cat room challenge model.

METHODS

This single-center, randomized, double-blind, placebo-controlled, 2-way crossover study consisted of a screening visit, 1 or 2 qualifying visits, and 2 treatment periods separated by a mean +/- SD washout period of 14 +/- 3 days. Patients were randomized to treatment sequence 1 (placebo followed by fexofenadine) or sequence 2 (fexofenadine followed by placebo). Baseline end points were obtained before study drug administration, and allergen challenges were initiated 1 1/2 hours after dosing. The primary end point was the change from predose baseline in the total symptom score (sum of rhinorrhea, itchy nose/palate/ throat, sneezing, and itchy/watery/red eyes) after 30 minutes of allergen exposure compared with placebo.

RESULTS

Of 211 patients screened, 66 were randomized and 63 completed the study. Mean change in the total symptom score from predose baseline was significantly less with fexofenadine compared with placebo 30 minutes after initiation of the cat allergen challenge (2 hours after dosing) (P = .03). The overall incidence of treatment-emergent adverse events was low and comparable for both groups.

CONCLUSION

Prophylactic treatment with a single dose of fexofenadine hydrochloride, 180 mg, significantly mitigated the worsening of allergic rhinitis symptoms induced by exposure to cat allergen compared with placebo use.

Experimental models for the evaluation of treatment of allergic rhinitis

OBJECTIVE

To review the experimental models used for the clinical evaluation of treatments for allergic rhinitis.

DATA SOURCES

Peer-reviewed clinical studies and review articles were selected from the PubMed database using the following relevant keywords: allergic rhinitis in combination with efficacy, wheal and flare, nasal challenge, park, cat room, or exposure unit. Regulatory guidance documents on allergic rhinitis were also included.

STUDY SELECTION

The authors' knowledge of the field was used to limit references with emphasis on recent randomized and controlled studies. References of historical significance were also included.

RESULTS

Traditional outpatient studies are universally accepted in the evaluation of treatment for allergic rhinitis. Experimental models provide ancillary information on efficacy at different stages of treatment development. Skin histamine and allergen challenge, as well as direct nasal challenge with histamine and allergen, are often used as early steps in assessing drug efficacy. Exposure units, park settings, and cat rooms better approximate real life by drawing on the natural mode of allergen exposure and delivering the sensitizing allergen to allergic individuals in the ambient air. Park studies make use of allergens in the outdoors, whereas cat rooms and exposure units present the sensitizing allergens indoors, with the latter providing consistent predetermined allergen levels. Exposure unit and park studies are acknowledged for the determination of onset of action and are also suited to the measurement of duration of effect and other measures of efficacy. Onset and duration of effect are 2 important pharmacodynamic properties of antihistamines and nasal corticosteroids as determined by the Allergic Rhinitis and Its Impact on Asthma and the European Academy of Allergology and Clinical Immunology workshop group.

CONCLUSIONS

All challenge models serve as important instruments in the evaluation of antiallergic medications and provide additional information to complement traditional studies.

Acoustic rhinometry in nasal allergen challenge study: which dimensional measures are meaningful?

BACKGROUND

Acoustic rhinometry (AR) is commonly used as a quantitative assessment of nasal response to nasal allergen challenge (NAC). However, sources of error and physical limitations of various AR area-distance measurements have not been adequately evaluated.

OBJECTIVE

To investigate the clinical value of AR measurements, and the relationship between subjective sensation and objective AR measurements in the NAC study.

METHODS

Nasal challenge using increasing concentrations of crude Blomia tropicalis (Bt) extracts (0.6, 6, and 60 microg/mL) was performed in 15 adult patients (eight males and seven females) with ongoing persistent allergic rhinitis. Subjective symptom scores of nasal obstruction were recorded together with the objective AR measurements of the minimum cross-sectional area (MCA), distance to MCA and cross-sectional area (CSA) at 3.3, 4.0 and 6.4 cm from the nostril, during the 7 h after the last challenge.

RESULTS

The dose-response increase in nasal obstruction score was significantly (P<0.001 for all) associated with decreases in mean MCA (r=0.75), mean CSA3.3 (r=0.54), mean CSA4.0 (r=0.53) and mean CSA6.4 (r=0.20). The mean MCA (+/-SD) for each subjective symptom score 0, 1, 2 and 3 was found to be 0.73 (+/-0.22) cm2, 0.63 (+/-0.29) cm2, 0.33 (+/-0.17) cm2 and 0.21 (+/-0.14) cm2, respectively. When the MCA (left and right separately) reached an area <0.2 cm2, measurements of CSA3.3 and CSA4.0 were significantly reduced by 60-70%.

CONCLUSION

This study demonstrates that AR is a useful and objective investigational tool, which correlates well with the sensation of nasal obstruction. MCA, CSA3.3 and CSA4.0 are more reliable measurements than CSA6.4 due to physical limitations. It is important to note that when the MCA is smaller than 0.2 cm2, a common condition in the early-phase reaction, area-distance measurements beyond this point can be misinterpreted and should be considered with caution.

The efficacy of montelukast in the treatment of cat allergen-induced asthma in children

BACKGROUND

Montelukast is a leukotriene antagonist approved for the treatment of childhood asthma in children age 2 years and older. There are limited studies on its effects on allergic asthma in children.

OBJECTIVE

We sought to evaluate montelukast's effects on upper and lower airway responses to intense cat allergen exposure.

METHODS

In a double-blind, placebo-controlled, cross-over trial 18 subjects aged 6 to 14 years with cat-induced asthma were randomly assigned to receive 1 week each of either montelukast or placebo, followed by a 1-hour cat challenge in an environmental exposure unit. Upper and lower respiratory tract symptoms were rated, and spirometry and acoustic rhinometry were performed. Challenges were stopped early if the subject became too uncomfortable or had a greater than 50% decrease in FEV1.

RESULTS

Overall changes in FEV1 were significantly different with montelukast treatment and remained significant after adjusting for allergen level (P =.02; adjusted P =.01). Lower respiratory tract symptom scores were significantly reduced with montelukast versus placebo (P =.007) but lost significance after adjusting for allergen level (P =.16). Challenge length was significantly longer with montelukast versus placebo (P <.001) and remained significant after adjusting for allergen level (P =.019). Montelukast did not significantly affect upper respiratory responses, as measured by means of symptom scores (P =.43) and changes in acoustic rhinometry (P =.078).

CONCLUSIONS

Montelukast was significantly more effective than placebo in attenuating lower respiratory responses and extending challenge length when cat-sensitive children with mild persistent asthma were exposed to high levels of cat allergen.

Effects of topical corticosteroid and combined mediator blockade on domiciliary and laboratory measurements of nasal function in seasonal allergic rhinitis

BACKGROUND

Both domiciliary and laboratory measures of nasal function have been used to evaluate treatment response in allergic airways disease; however, these measures have not been compared.

OBJECTIVE

To determine the relationship of domiciliary measures (daily symptoms, peak inspiratory nasal flow, and nasal oral index) and laboratory measures (rhinomanometry, acoustic rhinometry) in assessing treatment response with topical steroids and specific inflammatory mediator blockage.

METHODS

Twenty-one patients with seasonal allergic rhinitis and asthma were enrolled into a single-blind, placebo-controlled, crossover study comparing 2 weeks of 1) 400 microg inhaled plus 200 microg intranasal budesonide once daily and 2) 10 mg montelukast plus 10 mg cetirizine once daily. Before each treatment, patients received 7 to 10 days of placebo period. Laboratory measurements were made of nasal resistance by posterior rhinomanometry, and nasal volume between 0 and 5 cm by acoustic rhinometry after both placebo and active treatment periods. Daily domiciliary recordings were made of allergic rhinitis nasal symptoms scores and peak nasal and oral inspiratory flow rate (enabling the calculation of a nasal/oral index) throughout the study.

RESULTS

There were significant (P < 0.05) improvements for all allergic rhinitis symptoms with both therapies, after factoring for pollen count. Spearman's rank correlation for comparison among nasal symptoms and the objective responses were: nasal inspiratory flow rate (R = -0.50, P = 0.02); nasal/oral index (R = -0.55 P = 0.01); rhinomanometry (R = 0.24, P = 0.30); and acoustic rhinometry (R = -0.21, P = 0.36).

CONCLUSIONS

Both treatments were effective in managing allergic rhinitis symptoms, and patients' symptoms were more closely associated with domiciliary measurements of nasal flow than laboratory measurements of nasal function.

Comparative oral and topical decongestant effects of phenylpropanolamine and d-pseudoephedrine

Nonselective adrenergic alpha-agonists such as phenylpropanolamine and d-pseudoephedrine are widely used as decongestants to treat nasal congestion associated with a variety of nasal diseases. Although the activity of these drugs is well established in clinical studies, a direct comparison of their nasal decongestant effect as determined by changes in nasal cavity dimensions and nasal architecture has not been studied. Using acoustic rhinometry, we evaluated the effects of these drugs on nasal cavity volume, minimum cross-sectional area (Amin), and the distance from the nosepiece to the Amin (Dmin) in a feline, pharmacological model of nasal congestion. Administration of topical compound 48/80 (1%), a mast cell histamine liberator, into the left nasal passageway decreased nasal volume by 66%, reduced Amin by 51%, and increased Dmin by 116%. The congestive responses to compound 48/80 (1%) were reproducible through six weeks. In a subset of cats, the nasal cavity volume effect of repetitive exposure to compound 48/80, given once every two weeks for six weeks, was not different from the nasal responses after the initial exposure to compound 48/80. Pretreatment with oral phenylpropanolamine (10 mg/kg) or oral d-pseudoephedrine (10 mg/kg) attenuated the nasal effects of compound 48/80, but were associated with a pronounced increase in systolic blood pressure of +51 and +82 mmHg, respectively. A similar decongestant profile was observed with phenylpropanolamine (1%) and d-pseudoephedrine (1%) when given topically. Topical phenylpropanolamine (1%) and d-pseudoephedrine (1%) 45 minutes after dosing increased blood pressure +44 and +17 mmHg, respectively, over control animals. We conclude that oral and topical phenylpropanolamine and d-pseudoephedrine display equieffective nasal decongestant activity and produce similar cardiovascular profiles characterized by significant increases in blood pressure.

A randomized, double-blind, placebo-controlled trial of the effect of zafirlukast on upper and lower respiratory responses to cat challenge

BACKGROUND

Zafirlukast, a leukotriene antagonist, has been shown to have protective effects against a variety of asthma triggers.

OBJECTIVE

Our purpose was to evaluate zafirlukast's effects on upper and lower airway responses to cat allergen exposure with use of a well-characterized cat exposure model.

METHODS

In a double-blind, placebo-controlled, cross-over trial 18 subjects with cat-induced asthma were randomly assigned to receive 1 week each of zafirlukast or placebo followed by a 1-hour cat challenge. Upper and lower respiratory symptoms were rated and spirometry and acoustic rhinometry were performed. Challenges were stopped early if the subject was too uncomfortable or had a >50% decrease in FEV(1).

RESULTS

Overall changes in FEV(1) were significantly different with zafirlukast treatment (P = .02). Significant differences in FEV(1) change were detected at 15 and 30 minutes (P = .027 and .05, respectively) but not at 45 and 60 minutes. Changes in acoustic rhinometry were also significantly different at 15 and 30 minutes (P =.05 and .0005, respectively) but not at 45 and 60 minutes. Challenge length was significantly longer with zafirlukast versus placebo after adjustment for differences in allergen exposure (P = .022). Respiratory symptom scores were significantly different (lower respiratory, P < .001; upper respiratory, P = .038) through the first 30 minutes of the challenge after adjustment for allergen exposure.

CONCLUSIONS

Zafirlukast was significantly more effective than placebo in preserving pulmonary function and nasal anatomy and extending challenge length when cat-sensitive asthmatic subjects were exposed to high levels of cat allergen.

Evaluation of acoustic rhinometry in a nasal provocation test with allergen

BACKGROUND

The objective was to validate acoustic rhinometry (AR) in a nasal challenge with allergen.

METHODS

Nasal response to allergen provocation was based on clinical and symptom scores, cross-sectional changes of the nasal mucosa as measured by AR with the Rhinoklack system, and peak nasal inspiratory flow (PNIF), in atopic and nonatopic volunteers.

RESULTS

After allergen challenge, mean variation in minimal cross-sectional area (deltaMCA), as measured by AR, or in peak nasal inspiratory flow (deltaPNIF) in nonatopic volunteers, was -0.4+/-14.3% and 5.2+/-15.7%, respectively, compared to baseline. This allowed the determination of a reaction threshold of -29% for deltaMCA and of -26% for deltaPNIF. All but one of the 30 atopic patients reached the AR reaction threshold, whereas all patients reached the PNIF reaction threshold. AR and PNIF closely correlated with clinical and symptom scores for nasal congestion, since there was no significant difference at reaction threshold between both methods.

CONCLUSIONS

In an allergen provocation test, AR appears to be as specific and sensitive as peak nasal inspiratory flow, with the advantage of being independent of the patient's active cooperation. Discrepancies between both methods emphasize the role of nasal cavity anatomy in measuring nasal congestion by AR.