P233 Structured light plethysmography correlates well with inspiratory muscle strength in pompe disease. (December 2018)

• Record Type: Journal Article
• Authors: Madathil, SC; Al-Asadi, A; Stockley, JA; Huq, S; Mukherjee, R; Cooper, BG; Geberhiwot, T
• Is Part Of: Thorax. Volume 73(2018)Supplement 4
• Page Start: A227
• Page End: A228
• Publication Date: 2018-12
• Subjects: Chest -- Diseases -- Periodicals; Thorax; Chest -- Diseases; Periodicals; Periodicals; 617.54
• DOI: 10.1136/thorax-2018-212555.390
• Languages: English
• ISSNs: 0040-6376

Abstract

Abstract : Introduction: This is the first study to use Structured Light Plethysmography (SLP) in patients with confirmed Pompe disease (PD) to look at respiratory function. PD or Glycogen storage disease 2 is an autosomal recessive metabolic disorder due to deficiency of the lysosomal enzyme acid alpha glucosidase. The resultant accumulation of glycogen affects various tissues including muscles, causing muscle weakness and, in many patients, ventilatory failure. SLP is a non-invasive, non-contact technique, utilising the movement of the thoraco-abdominal (TA) wall to measure a range of breathing-related parameters. A structured light grid is projected on to the thorax and abdomen as the subject breathes and a 5 min dynamic recording is made. Methods: 16 patients (Mean [SD] Age (years)=53.0 [12.7]; M:F=4:12) with adult onset PD performed sitting and supine SLP for 5 min (Pneumacare, Ely, UK) as well as routine respiratory muscle function. SLP parameters included Phase Angle (PA), which is a measure of thoraco-abdominal synchronicity. The routine parameters measured included sitting and supine Vital Capacity (VC), Maximal Inspiratory Pressure (MIP), Maximal Expiratory Pressure (MEP) and Sniff Nasal Inspiratory Pressure (SNIP), using Ultima system (MedGraphics UK) to ATS/ERS 2005 standards. Results: Complete data was obtained in 12 patients and showed overall reduced (<−1.64 SR) lung function (Mean [SR] FVC=−2.1 (SR); Change% in VC (sitting-supine)=−29.7% (15.8); SNIP=−32.7 (±10.3) cmH2 O), consistent with respiratory muscle weakness. We tested correlations of PA sitting and supine with SNIP, MIP, MEP and fall in VC sitting-supine. There were moderate-strong correlations between sitting PA and both MIP (r 2 =0.539, p<0.0001) and SNIP (r 2 =0.700, p<0.0001) (figure 1) but there were no other significant correlations. Conclusions: We have demonstrated that PA by SLP can be used to monitor respiratory muscle strength in PD, since it shadows SNIP and MIP across the clinical range. There could be a potential role of using SLP for assessing respiratory muscle function in other neurological conditions especially where standard respiratory muscle function testing is challenging.