Use of Nasal Carbon Dioxide for Relief of Perennial Allergic Rhinitis

This study was conducted to test the safety and effectiveness of nasal carbon dioxide treatment on patients with symptoms of perennial allergic rhinitis. This was a randomized, double-blind, placebo-controlled, multicenter, in-clinic study carried out with two different flow rates of carbon dioxide (5 or 10 mL/sec) and for two different periods (10 or 30 seconds per nostril) of time. The total nasal symptom score (TNSS; derived as the sum of the average of symptoms of nasal congestion, itching, rhinorrhea and sneezing) was found to decrease in the groups treated with nasal carbon dioxide as compared to the placebo treatment groups.

Allergic rhinitis, an allergic inflammation of the nasal airways, affects around 30 to 60 million people in the United States. The current treatment methods of allergic rhinitis include allergen avoidance, pharmacotherapy (antihistamines, topical sympathomimetics) or intra-nasal steroids. However, the use of these methods, especially steroids given to children, is still an area of concern. These methods have not satisfied patients because of the persistence of symptoms even after treatment. The methods have also reduced the quality of life. Previous research has proven that nasal carbon dioxide treatment at a flow rate of 10 mL/sec and for 60 seconds per nostril is effective for the treatment of seasonal allergic rhinitis (which occurs only during the pollen seasons). This study examined the efficacy of this treatment for shorter durations of time.

* In this study, 348 men and women, aged 18 to 65 years, suffering from allergic rhinitis since the age of 2 were enrolled.
* Patients with other clinically significant nasal disorders, other serious medical conditions, and the patients who were on concomitant medications were excluded from this study.
* Carbon dioxide was delivered via a nosepiece attachment.
* The subjects were stratified into two groups based on the duration of administration as 10 sec/nostril and 30 sec/nostril. They were further divided into six  groups. Group A: 5 mL/sec for 10 sec/nostril; Group B: 10 mL/sec for 10 sec/nostril; Group E: 0 mL/sec (placebo) for 10 sec/nostril; Group C: 5 mL/sec for 30 sec/nostril; Group D: 10 mL/sec for 30 sec/nostril; and Group F: placebo for 30 sec/nostril.
* The symptoms were self-rated by patients on a six-point TNSS scale and total non-nasal symptom score (TNNSS – sum of the average of symptoms of itchy eyes, watery eyes, eye redness, itchy ears, or throat) scale. The TNSS scores were compared before and after the treatment at different time intervals in the clinic for four hours and outside the clinic for up to 24 hours.

Results/Key findings
* The decrease in TNSS score from the baseline was greater for nasal carbon dioxide treatment as compared to placebo at all flow rates and duration.
* The significant decrease in TNSS and TNNSS scores was observed for the subjects treated at 10 mL/sec flow rate and at 10 sec/nostril, which lasted for about four hours.
* The subsequent increase in the duration of treatment (30 seconds) did not show much improvement compared to the 10-second treatment.
* The rate of improvement of symptoms in the carbon dioxide group was rapid (30 minutes) and was sustained for longer period of time (four to six hours).
* Nasal discomfort, headache and lacrimation were the common adverse events that were reported.

Next steps/Shortcomings
No carbon dioxide was administered to the placebo group. The reason for the decrease in the symptoms in this group was not completely understood. There is a need for developing hand-held devices for administration of a gas, such as carbon dioxide, which will make its use comfortable for patients. Future studies need to be conducted to confirm the efficacy of the treatment and also to examine its use in nonallergic rhinitis cases.

Nasal carbon dioxide treatment can be very effective for the symptomatic treatment of perennial allergic rhinitis. This study has shown that it is also safe, especially for very young and very old patients. It was observed that there was an improvement in all the major symptoms of rhinitis within 30 minutes after administration of carbon dioxide. No serious systemic effects were seen due to carbon dioxide administration. The adverse events reported were not very severe and were found to resolve on withdrawal of the study drug administration. The rapid onset of relief of symptoms makes it suitable to use it “on an as-needed basis.”

For More Information:
Nasal Carbon Dioxide for the Symptomatic Treatment of Perennial Allergic Rhinitis

Publication Journal: Annals of Allergy, Asthma & Immunology, March 2011
By Thomas B. Casale, MD; Phillip E. Korenblat, MD; Creighton University, Omaha, Nebraska; The Clinical Research Center, St. Louis, Missouri

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