An implantable ventilator augments inspiration in an in vivo porcine model

Severe diaphragm dysfunction can lead to respiratory failure, requiring permanent mechanical ventilation. Permanent tethering to a mechanical ventilator via a patient’s mouth or tracheostomy can interfere with quality of life and autonomy by hindering activities like speech and swallowing. We present a diaphragm assist system that intervenes internally at the diaphragm as opposed to the mouth. By implanting contractile, soft robotic actuators above the diaphragm to push downwards and augment diaphragm motion during inspiration, this diaphragm assist system functions as an implantable ventilator. We demonstrate the proof-of-concept feasibility of this system to augment physiological metrics of ventilation in an in vivo porcine model of varied respiratory insufficiency. Synchronized actuation of the assist system with native respiratory effort augmented the tidal volume by up to a 100 mL increase and was capable of improving minute ventilation into a normal range. The diaphragm assist system has the potential to provide a new therapeutic ventilation option that aims to restore respiratory performance without sacrificing quality of life.

Characterisation of hemidiaphragm dysfunction using dynamic chest radiography: a pilot study

ObjectivesDynamic chest radiography (DCR) is a novel real-time digital fluoroscopic imaging system that produces clear, wide field-of-view diagnostic images of the thorax and diaphragm in motion, alongside novel metrics on moving structures within the thoracic cavity. We describe the use of DCR in the measurement of diaphragm motion in a pilot series of cases of suspected diaphragm dysfunction.MethodsWe studied 21 patients referred for assessment of diaphragm function due to suspicious clinical symptoms or imaging (breathlessness, orthopnoea, reduced exercise tolerance, and/or an elevated hemidiaphragm on plain chest radiograph). All underwent DCR with voluntary sniff manoeuvres.ResultsParadoxical motion on sniffing was observed in 14 patients, and confirmed in 6 who also underwent fluoroscopy or ultrasound. In 4 patients, DCR showed reduced hemidiaphragm excursion but no paradoxical motion; in 3, normal bilateral diaphragm motion was demonstrated. DCR was quick to perform, well-tolerated in all cases and with no adverse events reported. DCR was achieved in around five minutes per patient, with images available to view by the clinician immediately within the clinical setting.ConclusionDCR is a rapid, well-tolerated and straightforward X-ray technique that warrants further investigation in the assessment of diaphragm dysfunction.

CT-derived 3D-diaphragm motion in emphysema and IPF compared to normal subjects

Image registration-based local displacement analysis enables evaluation of respiratory motion between two computed tomography-captured lung volumes. The objective of this study was to compare diaphragm movement among emphysema, idiopathic pulmonary fibrosis (IPF) and normal subjects. 29 normal, 50 emphysema, and 51 IPF subjects were included. A mass preserving image registration technique was used to compute displacement vectors of local lung regions at an acinar scale. Movement of the diaphragm was assumed to be equivalent to movement of the basal lung within 5 mm from the diaphragm. Magnitudes and directions of displacement vectors were compared between the groups. Three-dimensional (3D) and apico-basal displacements were smaller in emphysema than normal subjects (P = 0.003, P = 0.002). Low lung attenuation area on expiration scan showed significant correlations with decreased 3D and apico-basal displacements (r = − 0.546, P < 0.0001; r = − 0.521, P < 0.0001) in emphysema patients. Dorsal–ventral displacement was smaller in IPF than normal subjects (P < 0.0001). The standard deviation of the displacement angle was greater in both emphysema and IPF patients than normal subjects (P < 0.0001). In conclusion, apico-basal movement of the diaphragm is reduced in emphysema while dorsal–ventral movement is reduced in IPF. Image registration technique to multi-volume CT scans provides insight into the pathophysiology of limited diaphragmatic motion in emphysema and IPF.