Association between low sniff nasal-inspiratory pressure (SNIP) and sleep disordered breathing in amyotrophic lateral sclerosis: Preliminary results

Abstract

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that rapidly involves the respiratory system, leading to persistent respiratory insufficiency. Neuromuscular respiratory weakness is also responsible for sleep disordered breathing (SDB), which occurs at an early stage of ALS. Maximal sniff nasal-inspiratory pressure (SNIP) is a sensitive test to early disclose respiratory muscle decline. The aim of this study was to evaluate the role of the SNIP test, compared to FVC, as a marker of SDB in ALS. We studied 31 (18 males) patients with ALS, who were divided into two groups according to the SNIP test value. Ten patients who showed a SNIP value higher than 60 cmH₂O were considered as group 1. Twenty-one patients exhibited a SNIP lower than 60 cmH₂O and were included in group 2. Both groups of patients were also investigated with nocturnal sleep study. A linear correlation between lower SNIP value and reduced nocturnal SaO₂ in patients with a SNIP value less than 60 cmH₂O (n = 21; r = 0.449; p = 0.04) was found. A negative correlation between SNIP and time spent in SaO₂ below 90% (TST90) (n = 21; r = −0.584; p = 0.0054), and between SNIP and oxyhaemoglobin desaturation index (ODI, events/hour) (n = 21; r = −0.458; p = 0.0368) was also established in all the patients of group 2, while, in this group, FVC did not correlate with any nocturnal parameter observed. A positive correlation between SNIP and PaO₂ at baseline of the entire population of patients (n = 31; r = 0.614; p < 0.001) was also seen. In conclusion, the results of this preliminary study show that SNIP < 60 cmH₂O might be considered an early predictor of SDB in ALS.

Key words::

• ALS
• SNIP
• sleep disordered breathing
• FVC

Aknowledgements

The authors are grateful to M. Damiani and V. Quaranta for statistical analysis and M. T. Ranieri for technical assistance.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.