ABSTRACT 449

Abstract

Background and aims: Two children with ventilator dependence secondary to spinal injury underwent insertion of bilateral Atrostim Implantable Phrenic Nerve Stimulators (IPNS). We studied both children, before and after insertion of IPNS, using Structured Light Plethysmography (SLP) (Thora3Di TM PneumaCare Ltd, UK), a novel non-invasive method which captures functional images of the lungs by analysing chest wall movement, and translates this data into pulmonary function outputs. Aims: We aimed to determine whether SLP could define changes in ventilatory pattern and effectiveness following IPNS. Methods: SLP (IRB approved) was used to assess compartmental change of Rib Cage (RC) v Abdominal (AB) and Right (RH) v left (LH) hemi-thorax. A Konno-Mead loop (KM) was derived from which KM Principal Angle (Phi), KM Spread, Overall phase (OPhi), Windowed phase (W phase), Phase breath (B phase) and a measure of variation of per-breath phase (B phase Ent) was calculated. Each child was monitored in a sitting and supine position both on invasive ventilation and on IPNS. Results: In both patients, in both positions, Phi became more negative with IPNS, indicating a shift from RC to an AC / diaphragmatic volume recruitment. There was an increase in KM spread in the supine position, but either no change or a negative change in the sitting position. KM Spread and Phase measurements became positive indicating a more complex multi phased mode of volume recruitment. B Phase Ent decreased in both positions indicating more respiratory stability. Conclusions: SLP offers a non–invasive method to objectively quantify and record the regional, idiosyncratic and positional effectiveness of IPNS, when compared to conventional ventilation.