Diaphragm dysfunction, lung aeration loss and weaning-induced pulmonary oedema in difficult-to-wean patients

Background Diaphragm dysfunction and weaning-induced pulmonary oedema are commonly involved during weaning failure, but their physiological interactions have been poorly reported. Our hypothesis was that diaphragm dysfunction is not particularly associated with weaning-induced pulmonary oedema. Methods It was a single-centre and physiological study conducted in patients who had failed a first spontaneous breathing trial and who underwent a second trial. The diaphragm function was evaluated by measuring the tracheal pressure generated in response to a bilateral magnetic phrenic nerves stimulations. Weaning-induced pulmonary oedema was diagnosed in case of failure of the spontaneous breathing trial if patients exhibited signs of plasma concentration or echocardiographic diagnosis of pulmonary artery occlusion pressure elevation. Results Fifty-three patients were included and 31/53 (58%) failed the spontaneous breathing trial, including 24/31 (77%) patients with weaning-induced pulmonary oedema. Diaphragm dysfunction was present in 33/53 (62%) patients. Diaphragm dysfunction or weaning-induced pulmonary oedema were present in 26/31 (84%) of the patients who failed the spontaneous breathing trial. Weaning-induced pulmonary oedema occurred in 20/33 (61%) patients with a diaphragm dysfunction and in 4/20 (20%) patients without (p = 0.005). Conclusion Weaning-induced pulmonary oedema was three times more frequent in case of diaphragm dysfunction. Even in case of diaphragm dysfunction, physicians might be encouraged to investigate the presence of weaning-induced pulmonary oedema during weaning failure.

Diaphragmatic paralysis resulting in respiratory failure as a feature of hepatitis E virus-associated neuralgic amyotrophy

Hepatitis E virus (HEV)-associated neuralgic amyotrophy (NA) is often bilateral and severe, involving structures outside the brachial plexus, such as the phrenic nerves or the lumbosacral plexus. We report a case of an HEV-positive man who had presented with brachial neuritis, with significant phrenic nerve involvement, resulting in diaphragmatic paralysis requiring non-invasive ventilation. Prognosis of HEV-associated NA is often unfavourable and recovery is usually incomplete. Identifying HEV-associated NA early could potentially aid in prognostication and management planning, as clinicians and patients would be expectant of its potential features and severity. Respiratory function should be monitored in patients with HEV who suffer from NA, as diaphragmatic paralysis could potentially lead to severe respiration difficulties requiring ventilatory support.

Cervical spondylosis as a possible hidden reason beyond delayed phrenic nerve distal motor latency

Background Cervical spondylosis is a chronic degenerative condition of the cervical spine that can affect the cervical nerve roots. The origin of the phrenic nerve makes it vulnerable to injury. The purpose of this study is to investigate possible subtle phrenic nerve affection in patients with cervical spondylosis using nerve conduction studies (NCS). This study was conducted on 30 patients with cervical spondylosis above C5 and on 30 healthy volunteers. Nerve conduction studies of both phrenic nerves were performed in all cases. Results The patients with cervical spondylosis showed a statistically highly significant prolongation of phrenic nerve distal motor latency (DML) than the control group (P < 0.01). There was no significant difference regarding amplitude (P > 0.05). There was a significant correlation between DML and X-ray score (r < 0.05). Conclusions Cervical spondylosis is an underestimated cause of phrenic nerve delayed DML. There is a correlation between the delay of phrenic nerve DML and the severity of cervical spondylosis.

Pericardiectomy for constrictive pericarditis

Chronic constrictive pericarditis results from inflammation and fibrosis of the pericardium. This situation eventually leads to impairment of diastolic filling and right heart failure. Once the diagnosis is made, because the disease is basically irreversible, a pericardiectomy is the mandatory treatment. The standard surgical treatment has been extensively described. The goal of this video tutorial is to render a visual explanation of the described techniques and to provide tips to help make the procedure easier to perform. The standard technique is performed through a median sternotomy, preferably without cardiopulmonary bypass if feasible. The procedure includes the complete removal of the anterior pericardium from phrenic nerve to phrenic nerve and the removal of the diaphragmatic pericardium and of part of the pericardium posterior to both phrenic nerves. Before starting the actual pericardiectomy procedure, it is useful to separate the pericardial rigid shell from the pleurae and from the diaphragm; this step allows the operator to see both phrenic nerves clearly and to give clear boundaries between the pericardium and the diaphragm, which are not often as clear as desirable due to fat, edema, inflammation, and scarring. Once a portion of the pericardium has been detached from the myocardium, it can be excised, making the portion yet to be removed more visible.

Neuralgic amyotrophy and hepatitis E infection: 6 prospective case reports

IntroductionHepatitis E virus (HEV) represents the main cause of enterically transmitted hepatitis worldwide. It is known that neuralgic amyotrophy (NA) is one of the most frequent neurological manifestations of HEV. However, clinical, electrodiagnostic (EDX) and MRI characteristics, as well as long-term follow-up of HEV-related NA have not been fully described yet.Case reportsWe describe longitudinally clinical, EDX, biological and MRI results of six cases of HEV-associated NA, diagnosed from 2012 to 2017. Patients were between the ages of 33 and 57 years old and had a positive HEV serology. Clinical patterns showed the whole spectrum of NA, varying from extensive multiple mononeuropathy damage to single mononeuropathy. EDX results showed that the patients totalised 26 inflammatory mononeuropathies (1 to 8 per patient). These involved classical nerves such as suprascapular (6/6 cases), long thoracic (5/6 cases) and accessory spinal nerves (2/6 cases) and, some less frequent more distal nerves like anterior interosseous nerve (3/6 cases), as well as some unusual ones such as the lateral antebrachial cutaneous nerve (1/6 case), sensory fibres of median nerve (1/6 case) and phrenic nerves (1/6 case). After 2 to 8 years, all nerves had clinically recovered (muscle examination above 3/5 on MRC scale for all muscles except in one patient).DiscussionHEV should be systematically screened when NA is suspected, whatever the severity, if the onset is less than 4 months (before IgM HEV-antibodies disappear) and appears to be frequently associated with severe clinical and EDX pattern, without increasing the usual recovery time.

Reliability of diaphragm voluntary activation measurements in healthy adults

Voluntary activation can be used to assess central fatigue of the diaphragm after tasks such as exercise or inspiratory muscle loading. Cervical magnetic stimulation (CMS) of the phrenic nerves elicits an involuntary contraction, or twitch of the diaphragm. This twitch is quantified based on a measure of transdiaphragmatic pressure (Pdi) and can be used to evaluate diaphragm contractile function and diaphragm voluntary activation (diaphragm-VA). The test-retest reliability of diaphragm-VA using CMS is currently unknown. Thirteen participants (4M:9F; 25±3 years) performed a series of interpolated twitch manoeuvres, which included a maximal inspiratory effort against a semi-occluded mouthpiece and two CMS-stimuli, one during the inspiratory manoeuvre and one after when the participant returned to functional residual capacity to quantify diaphragm-VA. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) measured between-day and within-session reliability of diaphragm-VA, respectively. Maximal diaphragm-VA values were 90±8% (SEM: 3.8%) and 91±7% (SEM: 3.8%) during visits 1 and 2 (p=0.781), respectively, and displayed ‘excellent’ between-day reliability (ICC:0.98; 95%CI:0.96-1.00; SEM: 1.5%). Our results suggest that assessing diaphragm-VA using CMS is reliable in young healthy adults. Measuring diaphragm-VA may provide additional insight into the consequences and mechanisms of diaphragm fatigue. Novelty bullets: • Magnetic stimulation of the phrenic nerves can reliably measure voluntary activation of the diaphragm • Diaphragm voluntary activation can be used to provide additional insight into fatigability of the diaphragm.

AB0941 NEURALGIC AMYOTROPHY AND HEPATITIS E INFECTION: REPORT OF 6 CASES AND REVIEW OF THE LITERATURE

Background:Neuralgic amyotrophy (NA) or Parsonage and Turner syndrome is triggered at least in 25% by a viral infection: parvovirus B19, CMV, HSV, etc... Recently, few cases of Hepatitis E Virus (HEV) related NA were reported. This particular association remains little known and is overlooked by most physicians. Besides, clinical, electrodiagnostic (EDX) and MRI characteristics, as well as evolution of HEV-related NA have not been fully described yet.Objectives:To describe 6 cases of HEV-related NA and to perform a review of the literature.Methods:We describe longitudinally clinical examination, electrodiagnostic (EDX), biological and MRI results of 6 cases of HEV-associated NA, diagnosed in our center.Results:The 6 cases were aged between 33 and 57 years old (mean 44.5), sex ratio was 5M/1F. All patients had positive IgM anti-HEV (serology) and a cervical MRI that could not explain clinical presentation. Overall, the 6 patients totalize 26 mononeuropathies (range 1 to 8 per patient), 5/6 patients had a severe presentation of NA, with bilateral and asymmetric symptoms (3 cases). HEV-related NA involved classical nerves such as supra-scapular (6 cases, twice bilaterally) and long thoracic nerves (5 cases), some less classical nerves like anterior interosseous nerve (3 cases, twice bilaterally), and some very unusual ones such as the lateral antebrachial cutaneous nerve (1 case) and the sensory fibers of median nerve (1 case). NA also involved accessory spinal (2 cases, once bilaterally) and phrenic nerves (1 case bilaterally), both originating from cervical plexus. The EDX pattern of these nerve lesions consisted of unique or multiple extensive asymmetric inflammatory mononeuropathies with severe axonal loss and numerous denervation signs damage involving mostly the supra-scapular. On scapular MRI (available for 5/6 patients), amyotrophy in at least one muscle was observed in all patients. Out of 26 nerves involved, after 12 months all had well recovered (above 3/5 MRC scale).Conclusion:HEV should be systematically screened when NA is suspected, whatever the severity, if the onset is less than 3 or 4 months (before IgMs anti-HEV disappear). HEV-related NA appears to be frequently associated with a severe pattern, without modifying the recovery usually observed.Disclosure of Interests:Romain Garofoli: None declared, Paul Seror: None declared, Jennifer Zauderer: None declared, Christelle Nguyen: None declared, François Rannou Grant/research support from: Pierre Fabre, Fidia, MSD, Pfizer, Bone Therapeutics, Expanscience, Grunenthal, Thuasne, Genévrier, Fondation Arthritis, Consultant of: Pierre Fabre, Fidia, MSD, Pfizer, Bone Therapeutics, Expanscience, Grunenthal, Thuasne, Genévrier, Speakers bureau: Pierre Fabre, Fidia, MSD, Pfizer, Bone Therapeutics, Expanscience, Grunenthal, Thuasne, Jean-Luc Drapé: None declared, Alexandra Roren: None declared, Marie-Martine Lefevre Colau: None declared