The Effect of a Cold Air Eucapnic Hyperventilation Test on Lower Respiratory Airways in Healthy Volunteers and Patients With Asthma (CLARINET)

In this study, we want to evaluate the feasibility and safety of a CAEH test in healthy volunteers and patients with asthma. We want to develop a CAEH test to differentiate patients with different types of asthma and exercise-induced bronchoconstriction from healthy volunteers and to evaluate whether the respiratory phenotype induced by cold air inhalation differs between subjects with asthma and healthy subjects. Furthermore, we want to evaluate whether the CAEH test is more robust over time compared to the EVH test. Previously, our lab has demonstrated that submaximal exercise at subfreezing temperatures in a climate chamber (-5°C) induces an acute respiratory response in patients with asthma and in healthy subjects who have been exposed to high PM10 (unpublished data). Finally, This study will serve as a preliminary study for a subsequent prospective study in which the results and optimized protocol obtained in this study will be used to further evaluate the feasibility of using this CAEH as a diagnostic tool in asthma compared to EIB (CLARINET2). The present study is required to develop a standardized CAEH test in a safe and feasible manner. This study will also help to identify appropriate endpoints (FEV1, multiple breath washout test, biomarkers…) of the subsequent studies.

Study Overview

• Status: Completed
• Conditions: Asthma (Diagnosis)
• Intervention / Treatment: Device: Cold air challenge

Detailed Description

In this study, we aim to develop a safe and feasible cold air (-15°C) eucapnic hyperventilation (CAEH) test protocol in which we can compare the lower airway responses between healthy volunteers and subjects with asthma. Consequently, we want to evaluate the effect of cold air inhalation on FEV1, respiratory symptoms, airway integrity, and local and systemic inflammation.

Primary endpoints

The primary endpoint of this study is to compare proportional change in FEV1, (% decrease) after a CAEH test in healthy volunteers and patients with mild to moderate asthma. Post-exposure will be calculated as a time-weighted average over the 30 min after the CAEH test. At each time point (pre-, 5, 10, 15, and 30 minutes post-exposure), FEV1 will be measured in triplicate.

Secondary endpoints

We want to evaluate whether and to what extent the inhalation of cold air during this CAEH test can induce changes in respiratory symptoms (including dyspnea, cough, mucus production, etc.), affects lower airway integrity (airway obstruction (FEV1/FVC), small airway dysfunction (FEF 25/75, lung ventilation inhomogeneity (LCI), bronchial hyperreactivity (PC20 AMP)) and whether it induces (local or systemic) inflammation (different biomarkers in sputum and blood, as defined in section 5.2).

These changes will be compared between healthy volunteers and predisposed subjects with mild to moderate asthma. The abovementioned responses and the proportional change in FEV1 after the CAEH test will be compared to a standard (21°C room air) eucapnic hyperventilation (EVH) test. Furthermore, we will compare the results obtained in this study to the results obtained in the ALASCAIR study of dr. Tatjana Decaesteker. Finally, the effects of the CAEH will be correlated to the amount of air pollution the subject was exposed to, in the days prior to the test (as this may have an effect on the responses to cold air inhalation in healthy volunteers, as found in the Alascair study (unpublished data)), by means of different questionnaires evaluating life style and exposure to air pollution (SF-36, AQLQ, ACQ, SQUASH,…).

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Belgium
  • Leuven, Belgium, 3000
    • UZ Leuven Gasthuisberg

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age between 18 and 65 years old at time of signing informed consent
• BMI between 18 and 28 kg/cm2
• Ability to give informed consent and to comply with study protocol, in the investigator's judgement
• Non-smoking or ex-smokers for at least 12 months with less than 10 pack years
• Normal spirometry

Group specific:

Histamine positive healthy controls: histamine bronchial challenge test (< 8 mg/ml) at screening Healthy controls: histamine bronchial challenge test (≥ 8 mg/ml) at screening

Patients with asthma:

• Physician-diagnosed asthma for at least 6 months
• Post-bronchodilator FEV1 of ≥ 80% at screening
• Documented airway reversibility either by means of post-bronchodilator reversibility of ≥ 12.% and ≥ 200 ml or in the previous 6 months or by means of documented airway hyperresponsiveness (histamine PC20 < 4 mg/ml) at screening
• Asthma control questionnaire (ACQ) ≤ 1.5
• Regular treatment with ICS with or without LABA (unchanged dose for at least 30 days) at a low or medium dose of ICS

Exclusion Criteria:

• Previous history of intubation or admission to ICU due to asthma
• Severe asthma exacerbation within one month prior to screening visit
• Treatment with oral or systemic steroids within one month prior to screening visit
• Previous treatment with biologics for asthma
• Other major concurrent pulmonary (such as COPD, cystic fibrosis, sarcoidosis, interstitial lung disease, Churg-Strauss syndrome, allergic bronchopulmonary aspergillosis, bronchiectasis) or cardiovascular disease
• Pregnancy

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Healthy volunteers with negative histamine provocation challenge; Healthy volunteers with negative histamine provocation challenge will perform the same tests as the other 2 arms. The healthy volunteers are assigned in this group after the histamine provocation challenge. All will perform one hyperventilation challenge at room temperature (EVH) and one with cold air (CACh) with pre- and post-exposure evaluation on FEV1, respiratory symptoms and local and systemic inflammation	Device: Cold air challenge; This intervention consists of a standardized cold air eucapnic hyperventilation test using a device that controls temperature, humidity, and ventilation. Airway responses are measured via spirometry and biospecimens (serum and sputum supernatant). It is distinguished from other studies by its prospective design and inclusion of both healthy and asthmatic participants; Other Names: Cold air hyperventilation test
Other: Healthy volunteers with positive histamine provocation challenge; Healthy volunteers with positive histamine provocation challenge will perform the same tests as the other 2 arms. The healthy volunteers are assigned in this group after the histamine provocation challenge. All will perform one hyperventilation challenge at room temperature (EVH) and one with cold air (CACh) with pre- and post-exposure evaluation on FEV1, respiratory symptoms and local and systemic inflammation	Device: Cold air challenge; This intervention consists of a standardized cold air eucapnic hyperventilation test using a device that controls temperature, humidity, and ventilation. Airway responses are measured via spirometry and biospecimens (serum and sputum supernatant). It is distinguished from other studies by its prospective design and inclusion of both healthy and asthmatic participants; Other Names: Cold air hyperventilation test
Other: Patients with asthma; Patients with asthma will perform the same tests as the other 2 arms. The healthy volunteers are assigned in this group after the histamine provocation challenge. All will perform one hyperventilation challenge at room temperature (EVH) and one with cold air (CACh) with pre- and post-exposure evaluation on FEV1, respiratory symptoms and local and systemic inflammation	Device: Cold air challenge; This intervention consists of a standardized cold air eucapnic hyperventilation test using a device that controls temperature, humidity, and ventilation. Airway responses are measured via spirometry and biospecimens (serum and sputum supernatant). It is distinguished from other studies by its prospective design and inclusion of both healthy and asthmatic participants; Other Names: Cold air hyperventilation test

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportional change in FEV1 after hyperventilation challenge	The proportional change in FEV1 after hyperventilation challenges compared to baseline were measured.	After each hyperventilation challenge: pre, immediately, 3, 5, 10, 15 and 30 minutes after the challenge

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in symptoms	We want to evaluate changes in respiratory symptoms after challenge. The degree of dyspnea and cough will be determined using BORG scale. This is a 0 to 10 scale.	From the first hyperventilation challenge until 1 day after the second
Lung function changes	Changes in lung function (FEV1/FVC, FEF25-75, LCI, PEF...) were measured after hyperventilation challenge	After each hyperventilation challenge
Inflammatory parameters	Inflammation was assessed in sputum and blood. Cytokines, allergic response, cellular response, DAMPs and measures of epithelial integrity were assessed. Differential cell count will be performed on sputum samples, determining eosinophilic (> 3% eosinophils), neutrophilic (> 61% neutrophils), pauci-granulocytic (< 3% eosinophilic, < 61% neutrophils) and mixed granulocytic (> 3% eosinophilic, > 61% neutrophils). Cytokines will be determined in sputum supernatant with a U-plex assay. Airway inflammation is determined with FeNO. < 25 ppm = eosinophilic inflammation less likely, between 25 - 50 ppm = need further interpretation with additional information and > 50 ppm = indication of eosinophilic airway inflammation. Systemic inflammation will be measured in serum using U-plex assay. allergic response is measured with skin prick automated test on 10 allergens and in serum with total IgE.	At baseline and after each hyperventilation challenge

Collaborators and Investigators

• Sponsor: KU Leuven
• Collaborators: Universitaire Ziekenhuizen KU Leuven
• Investigators: Principal Investigator: Lieven Dupont, KU Leuven/UZ Leuven

Study record dates

Study Major Dates

• Study Start (Actual): August 4, 2023
• Primary Completion (Actual): November 27, 2024
• Study Completion (Actual): November 27, 2024

Study Registration Dates

• First Submitted: October 23, 2025
• First Submitted That Met QC Criteria: October 23, 2025
• First Posted (Estimated): October 24, 2025

Study Record Updates

• Last Update Posted (Estimated): October 24, 2025
• Last Update Submitted That Met QC Criteria: October 23, 2025
• Last Verified: October 1, 2025

More Information

Terms related to this study

• Keywords: Cold air hyperventilation; Asthma diagnosis
• Additional Relevant MeSH Terms: Pathologic Processes; Immune System Diseases; Respiratory Tract Diseases; Lung Diseases; Bronchial Diseases; Lung Diseases, Obstructive; Respiratory Hypersensitivity; Hypersensitivity, Immediate; Hypersensitivity; Pathological Conditions, Signs and Symptoms; Asthma; Disease
• Other Study ID Numbers: S66825

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes