Assessment and management of respiratory function in patients with Duchenne muscular dystrophy: current and emerging options

Figures & data

Table 1 Assessment of ventilatory function in DMD

		Functional parameter	Measurement method(s)
Non-invasive	Non-volitional	Electrical activity respiratory muscles	Transcutaneous surface electromyography (sEMG) with surface electrodes
		Breath-by-breath ventilatory pattern during quiet breathing at rest	Pneumotachograph with mask (or mouthpiece)
		Thoraco-abdominal kinematics	Magnetometers (diameters), respiratory inductive plethysmography (cross-sectional areas), opto-electronic plethysmography (total and compartmental chest wall volumes)
		Diaphragm shape and displacement	Magnetic resonance imaging (MRI)
		Displacement of dome, length of apposition zone, and thickness of the diaphragm	Ultrasound (US) imaging
	Volitional	Maximal static inspiratory (MIP) and expiratory (MEP) pressures	Pressure transducers with mask (or mouthpiece)
		Sniff nasal inspiratory pressure (SNIP)	Pressure transducers with nostril plug
		Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF) and cough peak flow (CPF)	Spirometer/pneumotachograph with mask (or mouthpiece)
		Total lung capacity (TLC), functional residual volume (FRC) and residual volume (RV)	Body plethysmography or spirometer + N2 washout techniques
		Tension time index (TTI)	Pressure transducers + pneumotachograph with mask (or mouthpiece)
Invasive	Non-volitional	Paradoxical breathing index (ΔPGA/ΔPDI)	Esophageal and gastric balloon-catheters with pressure transducers
		Strength of the diaphragm (Peak PDI)	Esophageal and gastric balloon-catheters with pressure transducers + magnetic stimulation of the phrenic nerve
		3D shape of the diaphragm	Volumetric computed tomography (CT) imaging
	Volitional	Strength of the inspiratory muscles (Peak POES)	Esophageal balloon-catheter with pressure transducers during sniff maneuver
		Strength of the diaphragm (Peak PDI)	Esophageal and gastric balloon-catheters with pressure transducers during sniff maneuver
		Strength of the expiratory muscles (Peak PGA)	Gastric balloon-catheter with pressure transducers during cough

Abbreviations: DMD, Duchenne muscular dystrophy; P_OES, esophageal pressure; P_GA, abdominal gastric pressure; P_DI, trans-diaphragmatic pressure.

Figure 1 Schematic diagram summarizing the natural course of the different respiratory functional parameters in DMD.

Notes: Upward arrow: increase; Downward arrow: decrease.
Abbreviations: FVC, forced vital capacity; MIP, maximal static inspiratory; P_DI, trans-diaphragmatic pressure; P_OES, esophageal pressure; RV, residual volume; P_GA, abdominal gastric pressure; SNIP, sniff nasal inspiratory pressure; TLC, total lung capacity; ERV, expiratory reserve volume; IRV, inspiratory reserve volume; DMD, Duchenne muscular dystrophy.