Correlation of diaphragm thickening fraction and oesophageal pressure swing in non-invasive ventilation of healthy subjects

Abstract

Abstract Introduction The diaphragm thickening fraction (DTF) may be a valuable tool for estimating respiratory effort in non-invasive ventilation. The primary aim of this physiological study is the investigation of the correlation of DTF with oesophageal pressure swings (ΔPoes). A secondary aim is to assess the discriminatory capacity of the index tests for different exercise loads. Methods Healthy volunteers underwent spontaneous breathing and non-invasive ventilation with a sequence of different respirator settings. The first sequence was carried out at rest. The same sequence was repeated twice, with additional ergometry of 25 and 50 Watts, respectively. DTF and ΔPoes were measured during each ventilation configuration. Results 23 individuals agreed to participate. DTF was moderately correlated with ΔPoes (repeated measures correlation ρ = 0.410, p < 0.001). Both ΔPoes and DTF increased consistently with exercise loading in every ventilation configuration, however ΔPoes showed greater discriminatory capacity. Conclusion DTF was moderately correlated with ΔPoes and could discriminate reasonably between exercise loads in a small cohort of non-invasively ventilated healthy subjects. While it may not accurately reflect the absolute respiratory effort, DTF might help titrating individual non-invasive respiratory support. Further investigations are needed to test this hypothesis. Trial Registration This study was not prospectively registered.

Keywords

• Diaphragm Thickening Fraction
• Ultrasound
• Oesophageal pressure
• Respiratory effort
• Non-invasive ventilation