Abstract Introduction Unilateral Diaphragm Paralysis (UDP) is an underrecognized cause of dyspnea. Prior case reports have not provided a detailed analysis of pulmonary function test abnormalities (PFT) in UDP. We report the clinical and PFT abnormalities in a cohort of patients from the Central California VA Medical Center with UDP of unknown etiology. Methods Subjects were identified by reviewing PFT data and SNIFF testing done over a period of four years. Patients with bilateral diaphragm paralysis, a history of progressive muscular dystrophy, post-traumatic diaphragm paralysis, coronary artery bypass grafting (CABG) associated diaphragm paralysis, radiation-induced diaphragm paralysis or lung malignancy were excluded. None of the patients had any documented cervical myelopathy. UDP was confirmed in all patients using the SNIFF test results. Clinical, radiological and pulmonary function testing (PFT) were collected from computerized medical charts. All normally distributed values were expressed as mean + standard deviation. Correlation was analyzed using Person’s coefficient. A probability value 0.05 was considered significant. Statistical analysis was performed using SPSS version 29. Results Among the 21 patients, all were male having served in navy 38%, air force 10% and army 52% with 60% reporting a history of smoking. The mean age was 76 + 6 years. Eight patients (38%) were referred for evaluation of COPD, while the remaining 62% were seen for evaluation of dyspnea on exertion. All patients were using a metered-dose inhaler (MDI) for dyspnea. After careful clinical chart review, a definite cause for UDP was not identified in any of these. patients. Asbestos exposure was reported in 67% and pleural plaques were observed on Chest CT in 71.4%. Pulmonary function data showed a mean Forced Vital Capacity (FVC) of 72.5% + 17.4%, Forced Expiratory Value in 1 second (FEV1) of 70.0% + 17.5%, Total Lung Capacity (TLC) of 86.0% + 15.5%, and Residual Volume (RV) of 122.4% +30.9%. MIP was 59.6% + 27.0% and MEP was 49.5% + 15.2%. Figure 1 A shows the PFT pattern and 1B shows a a significant negative correlation (R = 0.6, p 0.007) between the MIP to FVC%. Conclusions Unilateral diaphragm paralysis presents with dyspnea on exertion and is frequently misdiagnosed as COPD. Spirometry showed a mild restrictive pattern with a significant elevation of RV and RV/TLC ratio. The MIP was a significant determinant of the low FVC in UDP compared to MEP. The aetiology for UDP among the veterans remains unclear and further studies using larger sample size are warranted. This abstract is funded by: None
Vempilly et al. (Fri,) studied this question.