Unilateral diaphragmatic paralysis: inspiratory muscles, breathlessness and exercise capacity

Abstract

BackgroundPatients 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.MethodsPulmonary 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 resultsInspiratory 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.ConclusionThe 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 Importance of the Diaphragm Muscle in Cardiac Rehabilitation after Myocardial Infarction

“…In addition to the instrumentation that evaluates the MIP, there is the sniff test or sniff nasal inspiratory pressures (SNIP) which can be measured with a digital manovacuometer. From this instrumentation it is possible to calculate the values of the pressures generated by the diaphragm (force) at the gastric (sniff Pga), esophageal (sniff Poes) and transdiaphragmatic (sniff Pdi) levels [51]. There is no gold standard reference for comparing SNIP values but a diaphragm that is not in dysfunction could have values of 52-150 cmH2O for sniff Poes, values of 82-204 cmH2O for sniff Pdi and values of 68-62 cmH2O for sniff Pga [51,52].…”

“…Tests for electrical or magnetic stimulation of the phrenic nerve for the diaphragm can be used, evaluating the response at rest or under stress, but these approaches are not always easy to find in clinical practice [29,51,53]. Electromyography can be used during instrumental examinations to obtain additional information [51].…”

Measurements of respiratory muscle function as diagnostic criteria for diaphragmatic paralysis

“…Alguns estudos descreveram pacientes com paralisia diafragmática unilateral e redução da força diafragmática relacionada com Pga baixa. (4,5) PULMÃO DIREITO A paralisia diafragmática, como no caso aqui relatado, deve ser considerada como possível causa de dispneia.…”

Effects of inspiratory muscle training on exertional breathlessness in patients with unilateral diaphragm dysfunction: a randomised trial

“…People with UDD are typically asymptomatic at rest, but often experience dyspnea on exertion, when lifting heavy objects, performing any overhead activity, bending forward, or lying down [2]. This can likely be explained by a worsening paradoxical response of gastric pressure with exertion and a compensatory recruitment of extradiaphragmatic respiratory muscles [4]. The prognosis of UDD varies depending on the etiology, with spontaneous recovery more frequently reported in cases of traumatic cause relative to neuropathy [5,6].…”