The investigators hypothesis is that there will be improvement in FEV1 in patients with severe asthma. This is a retrospective data study that reviews preexisting medical records; no patients will be enrolled.

The investigators plan is to retrospectively evaluate spirometry on patients with severe asthma who have undergone bronchial thermoplasty. The procedure will have been done according to the recommended protocol of three separate sessions. For each patient all available spirometric data obtained before and after thermoplasty will be used. Data will be collected from two centers, OU Medical Center and St. Francis Hospital in Tulsa, OK. All procedures done at St. Francis have been performed by a single physician and he is providing their spirometric data for the investigators study. The following data will be collected for all participants undergoing bronchial thermoplasty: Age, height, sex, weight, medical history, smoking history, baseline spirometry before and after bronchodilators, post thermoplasty spirometry before and after bronchodilators.

Inclusion Criteria:

• >18 years of age
• severe asthma diagnosis
• decreased FEV1

Exclusion Criteria:

• < 18 years of age

Retrospective review of Asthma Patients' records

Deidentified data may only be shared upon review of OUHSC Legal office and IRB. Data sharing agreement required. Contact research@ouhsc.edu to initiate data requests. No personally identifiable data will be shared.