PT - JOURNAL ARTICLE AU - Mayra Caleffi Pereira AU - Letícia Z. Cardenas AU - Jeferson G. Ferreira AU - Vinícius C. Iamonti AU - Pauliane Vieira Santana AU - André Apanavicius AU - Pedro Caruso AU - Angelo Fernandez AU - Carlos R.R. de Carvalho AU - Daniel Langer AU - André L.P. de Albuquerque TI - Unilateral diaphragmatic paralysis: inspiratory muscles, breathlessness and exercise capacity AID - 10.1183/23120541.00357-2019 DP - 2021 Jan 01 TA - ERJ Open Research PG - 00357-2019 VI - 7 IP - 1 4099 - http://openres.ersjournals.com/content/7/1/00357-2019.short 4100 - http://openres.ersjournals.com/content/7/1/00357-2019.full SO - erjor2021 Jan 01; 7 AB - Background Patients with unilateral diaphragmatic paralysis (UDP) may present with dyspnoea without specific cause and limited ability to exercise. We aimed to investigate the diaphragm contraction mechanisms and nondiaphragmatic inspiratory muscle activation during exercise in patients with UDP, compared with healthy individuals.Methods Pulmonary function, as well as volitional and nonvolitional inspiratory muscle strength were evaluated in 35 patients and in 20 healthy subjects. Respiratory pressures and electromyography of scalene and sternocleidomastoid muscles were continuously recorded during incremental maximal cardiopulmonary exercise testing until symptom limitation. Dyspnoea was assessed at rest, every 2 min during exercise and at the end of exercise with a modified Borg scale.Main results Inspiratory muscle strength measurements were significantly lower for patients in comparison to controls (all p<0.05). Patients achieved lower peak of exercise (lower oxygen consumption) compared to controls, with both gastric (−9.8±4.6 cmH2O versus 8.9±6.0 cmH2O) and transdiaphragmatic (6.5±5.5 cmH2O versus 26.9±10.9 cmH2O) pressures significantly lower, along with larger activation of both scalene (40±22% EMGmax versus 18±14% EMGmax) and sternocleidomastoid (34±22% EMGmax versus 14±8% EMGmax). In addition, the paralysis group presented significant differences in breathing pattern during exercise (lower tidal volume and higher respiratory rate) with more dyspnoea symptoms compared to the control group.Conclusion The paralysis group presented with exercise limitation accompanied by impairment in transdiaphragmatic pressure generation and larger accessory inspiratory muscles activation compared to controls, thereby contributing to a neuromechanical dissociation and increased dyspnoea perception.The exercise capacity limitation in patients with unilateral diaphragmatic paralysis is characterised by an inefficient hemidiaphragm contraction. Consequently, there is a neuromechanical dissociation with an overload of inspiratory accessory muscles and higher breathlessness. https://bit.ly/2XxAR4K