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Objective: Determine if the middle ear transmucosal nitrous oxide (N2O) exchange rate is affected by nasal inflammation caused by topical application of histamine. Methods: In a randomized, double-blind, crossover study, 20 adults were challenged intranasally with histamine (5 mg) and placebo on separate occasions. At each session, the subjects were fitted with a non-rebreathing mask and breathed room air for 20 minutes, 50% N2O:50% O2 for 20 minutes, and 100% O2 for 10 minutes. Throughout, heart rate, blood pressure, and blood O2 saturation were monitored, and bilateral middle ear pressure was recorded by tympanometry every minute. The primary outcome measure was the slope of the middle ear pressure-time function for the 50% N2O:50% O2 breathing period, which is a measure of the transmucosal N2O exchange-constant. The effects of challenge substance, session, and period on the measured vital signs and of treatment, session, ear disease history, and test ear on the pressure-time slopes were evaluated using repeated measures ANOVAs. Results: The post-challenge total symptom score and the slope of the middle ear pressure-time function were greater after histamine when compared to placebo challenge. Of the signs, only heart rate was affected, responding to challenge substance and study period. Conclusion: The transmucosal N2O exchange rate for the middle ear is increased during inflammation caused by nasal histamine exposure. [ABSTRACT FROM AUTHOR]

Background: Platelet-activating factor (PAF) is a lipid mediator produced by most inflammatory cells. Clinical and experimental findings suggest that PAF participates in allergic rhinitis (AR) pathogenesis. The aim was to assess the PAF ability to induce clinical response in nasal airway after local stimulation. Method: Ten nonatopic healthy volunteers (HVs) and 10 AR patients out of pollen season were enrolled. PAF increasing concentrations (100, 200, and 400 nM) were instilled into both nasal cavities (0, 30, and 60 minutes, respectively). Nasal symptoms (congestion, rhinorrhea, sneezing, itching, and total 4 symptom score and nasal volume between the 2nd and 5th cm (Vol2-5) using acoustic rhinometry (AcR), were assessed at -30, 0, 30, 60, 90, 120, and 240 minutes. Result: PAF increased individual and total nasal symptom score in both HVs and seasonal AR (SAR) patients from 30 to 120 minutes (maximum score at 120′, p < 0.05). Nasal obstruction was the most relevant and lasting nasal symptom. PAF also induced a significant reduction of Vol2-5 at 90′ (27%), 120′ (38.7%), and 240′ (36.4%). No differences in the response to PAF nasal challenge were observed between HVs and SAR subjects in either clinical symptoms or AcR. Conclusion: This is the first description of PAF effects on human nasal mucosa using a cumulative dose schedule and evaluated by both nasal symptoms and AcR. Nasal provocation with PAF showed long-lasting effects on nasal symptoms and nasal obstruction in HVs and in patients with SAR. Nasal challenge may be a useful tool to investigate the role of PAF in AR and the potential role of anti-PAF drugs. [ABSTRACT FROM AUTHOR]

Background: Nasal nitric oxide (nNO) levels after nasal lysine acetylsalicylic acid (lys-ASA) challenge have not been determined. This study was designed to determine a pattern of changes after lys-ASA challenge in aspirin-exacerbated respiratory disease (AERD) patients and to evaluate the usefulness of nNO measurements in the assessment of lys-ASA nasal challenge outcome. Methods: Eighteen patients with aspirin hypersensitivity, nasal polyps, and asthma were included. Aspirin-tolerant control groups consisted of 10 healthy volunteers without asthma and nasal polyps and 10 patients with nasal polyps without asthma. All subjects underwent nasal challenge with lys-ASA. nNO was measured before and 1, 2, 4, and 24 hours after control solution and lys-ASA administration. Results: A significant fall in nNO levels was noted in AERD patients with a positive result to challenges at time points 1 hour (p = 0.0033), 2 hours (p = 0.0033), and 3 hours (p = 0.026) after lys-ASA. A trend toward higher nNO concentrations was observed after lys-ASA challenge at the 2-hour (p = 0.018) and 4-hour (p = 0.018) time points compared with baseline in subjects with AERD and a clinically negative result to the challenge. No significant changes in nNO levels after the challenge were observed in control groups. The combined increase and decrease in nNO levels gave the sensitivity as 0.94 and specificity 1.00 at best. Conclusion: nNO levels decrease after lys-ASA nasal challenge in subjects with AERD and a clinically positive result of the challenge. An unexpected trend toward an increase in nNO levels is observed in subjects with AERD and a clinically negative result of the challenge. [ABSTRACT FROM AUTHOR]