TransMEM Gas Exchange -- Project 1, Aim 2

• Status: Completed
• Trial end date: 2019-03-22
• Target enrollment: 0
• Participant gender: All

Summary

This study will determine if exposure to an allergy material (ragweed) or exposure to an allergic-symptom-provoking substance (histamine) and medications typically used to decongest the nose changes the rate of blood-flow in the lining of the middle-ear. Otitis media (the build-up of water-like fluid in the middle-ear airspace) may occur if the blood flow in the lining of the middle-ear is too high and may be prevented if a way could be found to lower the blood flow in persons susceptible to the disease. Middle-ear blood flow is measured indirectly by measuring the change in middle-ear pressure while a person breathes a gas mixture containing nitrous oxide ("laughing gas"). In this study, 4 groups of subjects will be entered and middle-ear pressure in persons breathing a mixture of 50% Oxygen, 50% Nitrous Oxide ("laughing gas")will be measured after exposure to one of four substances (ragweed, histamine,an oral decongestant, a decongestant nasal spray) and a fake medication (placebo) at separate test sessions. All subjects will have one set of 2 x-rays of the middle ears and mastoids. The group exposed to ragweed will require 3 study visits while the other 3 groups will have 2 study visits. From this information middle-ear blood flow will be calculated. This will help determine the relationship between what happens in the nose and what happens in the middle ear.

• Phase: Phase 1
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: Cuneyt M. Alper; University of Pittsburgh
• Collaborator: National Institute on Deafness and Other Communication Disorders (NIDCD)
• Treatments: Ephedrine; Histamine; Histamine phosphate; Oxymetazoline; Phenylephrine; Pseudoephedrine

Criteria

Inclusion Criteria:

• healthy

• no evidence of otitis media at entry

• bilaterally intact tympanic membranes

• ragweed arm: history of symptomatic ragweed allergy and Class 2 positive on RAST testing with or without other allergic sensitivities by history

Exclusion Criteria:

• craniofacial syndrome (ef, cleft palate)

• Use of prescription medications (except for birth control) in the 1 month prior to entry;

• Use of over-the-counter allergy medication within 2 weeks before challenge (Experiments 1, 2 only);

• Use of over-the-counter decongestants (nasal or oral) within 2 weeks before challenge (Exp 3,4 only)

• Elevated blood pressure (>140/90);

• Individuals with any pulmonary or cardiac problems, including asthma;

• Individuals who are pregnant or who are planning to become pregnant during the period of study;

• Individuals who had immunotherapy for ragweed allergy at any time (Experiment 1 only);

• Individuals who used any experimental medication or treatment within 3 months of screening;

• Individuals with extant unilateral or bilateral otitis media as documented by otoscopy or tympanometry;

• Individuals with abnormally low tympanic membrane mobility, eg Type B tympanogram;

• Individuals reporting a previous adverse experience with breathing gas mixtures containing N2O (e.g. during dental procedures);

• Individuals who have upper respiratory ("cold") symptoms or allergic rhinitis symptoms (may be rescheduled);

• Individuals with single or multiple allergic sensitivities by screening history (Experiment 2 only)