Measuring inspiratory muscle strength using sniff nasal inspiratory pressure in Huntington’s Disease. [Abstract C08]

Background: Respiratory failure is a common end point in the life of someone with Huntington’s disease (HD) yet little is known about respiratory function throughout the disease trajectory. It is necessary to measure respiratory muscle strength in order to identify, monitor and manage any weakness. Measurement of respiratory muscle strength may be difficult in people with neurological conditions due to inability to keep the mouthpiece in place. An alternative measurement technique is to use sniff nasal inspiratory pressure (SNIP) that uses a more automatic sniff. We have assessed the reliability of using SNIP in healthy people and are now assessing its use in people with HD. Methods: Within-day and between-day reliability was assessed using one measurer. Twenty healthy control subjects took fifteen sniffs on three occasions separated by a 10 minute rest in one day and again one week later. The maximum sniff on each occasion was recorded. Results: SNIP has excellent reliability as identified by intraclass correlation coefficients of 0.93 [mean difference -8 cm (± 10) H2O] for within-day and 0.93 [mean difference -3.6 cm (± 13) H2O] for between-day reliability. All points, except one, were within 95% limits of agreement. Conclusion: SNIP is a highly reliable, simple method for measuring inspiratory pressure in healthy control subjects. We will also present data on the use of SNIP in people with early and moderate/advanced HD