Date of Award


Degree Type

Selective Evidence-Based Medicine Review

Degree Name

Master of Science in Health Sciences - Physician Assistant

Department Chair

John Cavenagh, PhD, PA-C


OBJECTIVE: The objective of this selective EBM review is to determine whether or not noninhaled intranasal carbon dioxide (CO2) gas is a safe and effective treatment for improvement of nasal symptoms of allergic rhinitis.

STUDY DESIGN: Systematic review of three randomized controlled trials published in 2008, 2011, and 2011.

DATA SOURCES: Three randomized controlled trials published after 2007 were obtained using PubMed.

OUTCOMES MEASURED: Number of sneezes and severity of nasal symptoms (nasal congestion, rhinorrhea) were recorded by subjects using an ordinal scale to obtain a Total Nasal Symptom Score (TNSS). Scores recorded before and after treatment were compared to reflect effectiveness of treatment.

RESULTS: Casale TB, Romero FA, Spierings EL (2008) and Casale TB, Korenblat PE, Meltzer EO et al. (2011) demonstrated a high incidence of adverse events during gas administration – most commonly nasal stinging and watery eyes. Baroody FM, Gavanescu L, Wang JH et al. (2011) did not record incidence of adverse events during gas administration. Casale et al. (2008) reported a significant (>75%) improvement of nasal symptoms following treatment (26.7%)
compared to placebo (3.4%). Baroody et al. (2011) reported significant improvement in sneezing and rhinorrhea only. Casale et al. (2011) established significant improvement in total nasal symptoms in only one experimental arm when the treatment was administered at 10mL/second x 10 seconds per nostril.

CONCLUSION: Evidence supporting the safety of noninhaled intranasal CO2 gas therapy is inconclusive at this time due to lack of research addressing administration more frequent than single-use. Despite the high incidence of adverse events observed during single-use treatment, none of these effects
were “serious” or “medically significant.” Evidence supporting the efficacy of this therapy is inconclusive at this time due to lack of reproducibility beyond the preliminary study with adequate blinding.