P108 Making waves: Evaluation of the use of impulse oscillometry in the assessment of inducible laryngeal obstruction (ILO), and determining the prevalence of ILO within a UK Northwest respiratory service. (11th November 2022) - Cruise, P
Abstract : Introduction: Inducible laryngeal obstruction (ILO) is an upper airway condition which describes a reversible narrowing of the larynx, leading to breathlessness symptoms. Due to poor recognition and similar presentation to asthma, the diagnosis of ILO can be delayed up to 4.8 years. The current gold standard assessment tool is currently laryngoscopy. However, there are inherent challenges with this invasive method. Aims: To determine the prevalence of ILO in a UK respiratory population. To evaluate the use of spirometry and impulse oscillometry as diagnostic tools for ILO, and their predictive ability to determine laryngoscopically- confirmed ILO. Method: 98 patients were included in the service evaluation: 68 females (mean ± SD : age 54 ± 15.9) and 30 males (mean ± SD : age 55 ± 14.2), all of whom had been referred to a Tertiary referral service. Prevalence calculations were used to determine the prevalence of ILO as well as to establish characteristics displayed in those who had been diagnosed with ILO. Binary logistic regression was also used to examine whether spirometry values (FEV1, FEV1/FVC and ERV) and IOS values (Z5 Hz, R5 Hz, Rin5) were associated with the likelihood of having an ILO diagnosis Results: The model incorporating spirometry parameters was statistically significant (p=0.00), with FEV1/FVC and ERV significantly contributing towards the model. This is suggestive that spirometry values FEV1/FVC and ERV can be potential predictors of diagnosing ILO. However, the model incorporating Z5 Hz, R5 Hz and Rin5 parameters was not statistically significant (p=0.129, p=0.119, p=0.061), and did not therefore significantly contribute towards the model. This is suggestive that the IOS values Z5 Hz, R5 Hz, Rin5 were not found to be potential predictors of diagnosing ILO. Conclusion: This study found spirometry values FEV1/FVC and ERV were significant predictors of a subsequent diagnosis of ILO. However, IOS values Z5 Hz, R5 Hz, Rin5 were not found to be predictors of diagnosing ILO in the model. Further prospective studies with larger patient groups may be useful to investigate any further value of the use of IOS as a clinical indicator in the assessment of ILO.