Ultrasound imaging of diaphragmatic motion.

The diaphragm is the key muscle of respiration, especially in infants. Diaphragmatic dysfunction and paralysis can have significant implications for medical management and treatment, and they can be challenging to diagnose by clinical parameters alone. Multiple imaging modalities are useful for assessing the diaphragm, but US - specifically M-mode US - offers several distinct advantages and few limitations compared to fluoroscopy, radiography, CT and MRI. The purpose of this manuscript is to discuss the pathophysiology of the diaphragm, review common indications for dynamic diaphragmatic US, describe optimal imaging technique, and discuss how to avoid imaging pitfalls.

A nomogram to predict mechanical ventilation in Guillain-Barré syndrome patients.

INTRODUCTION: Guillain-Barré syndrome (GBS) is one of the most common causes of acute flaccid paralysis, with up to 20%-30% of patients requiring mechanical ventilation. The aim of our study was to develop and validate a mechanical ventilation risk nomogram in a Chinese population of patients with GBS. METHODS: A total of 312 GBS patients were recruited from January 1, 2015, to June 31, 2018, of whom 17% received mechanical ventilation. The least absolute shrinkage and selection operator (LASSO) regression model was used to select clinicodemographic characteristics and blood markers that were then incorporated, using multivariate logistic regression, into a risk model to predict the need for mechanical ventilation. The model was characterized and assessed using the C-index, calibration plot, and decision curve analysis. The model was validated using bootstrap resampling in a prospective study of 114 patients recruited from July 1, 2018, to July 10, 2019. RESULTS: The predictive model included hospital stay, glossopharyngeal and vagal nerve deficits, Hughes functional grading scale scores at admission, and neutrophil/lymphocyte ratio (NLR). The model showed good discrimination with a C-index value of 0.938 and good calibration. A high C-index value of 0.856 was reached in the validation group. Decision curve analysis demonstrated the clinical utility of the mechanical ventilation nomogram. CONCLUSIONS: A nomogram incorporating hospital stay, glossopharyngeal and vagal nerve deficits, Hughes functional grading scale scores at admission, and NLR may reliably predict the probability of requiring mechanical ventilation in GBS patients.

Consensus-Based Care Recommendations for Pulmonologists Treating Adults with Myotonic Dystrophy Type 1.

PURPOSE OF REVIEW: Myotonic dystrophy type 1 (DM1) is a severe, progressive genetic disease that affects approximately 1 in 2,500 individuals globally [Ashizawa et al.: Neurol Clin Pract 2018;8(6):507-20]. In patients with DM1, respiratory muscle weakness frequently evolves, leading to respiratory failure as the main cause of death in this patient population, followed by cardiac complications [de Die-Smulders et al.: Brain 1998;121(Pt 8):1557-63], [Mathieu et al.: Neurology 1999;52(8):1658-62], [Groh et al.: Muscle Nerve 2011;43(5):648-51]. This paper provides a more detailed outline on the diagnostic and management protocols, which can guide pulmonologists who may not have experience with DM1 or who are not part of a neuromuscular multidisciplinary clinic. A group of neuromuscular experts in DM1 including pulmonologists, respiratory physiotherapists and sleep specialists discussed respiratory testing and management at baseline and during follow-up visits, based on their clinical experience with patients with DM1. The details are presented in this report. RECENT FINDINGS: Myotonic recruited 66 international clinicians experienced in the treatment of people living with DM1 to develop and publish consensus-based care recommendations targeting all body systems affected by this disease [Ashizawa et al.: Neurol Clin Pract. 2018;8(6):507-20]. Myotonic then worked with 12 international respiratory therapists, pulmonologists and neurologists with long-standing experience in DM respiratory care to develop consensus-based care recommendations for pulmonologists using a methodology called the Single Text Procedure. This process generated a 7-page document that provides detailed respiratory care recommendations for the management of patients living with DM1. This consensus is completely based on expert opinion and not backed up by empirical evidence due to limited clinical care data available for respiratory care management in DM patients. Nevertheless, we believe it is of relevance for professionals treating adults with myotonic dystrophy because it addresses practical issues related to respiratory management and care, which have been adapted to meet the specific issues in patients with DM1. SUMMARY: The resulting recommendations are intended to improve respiratory care for the most vulnerable of DM1 patients and lower the risk of untoward respiratory complications and mortality by providing pulmonologist who are less experienced with DM1 with practical indications on which tests and when to perform them, adapting the general respiratory knowledge to specific issues related to this multiorgan disease.

Post-operative paralysis and elective ventilation reduces anastomotic complications in esophageal atresia: a systematic review and meta-analysis.

AIM OF STUDY: The repair of esophageal atresia (EA) carries an increased risk of anastomotic leak and stricture formation, especially in patients with anastomotic tension. To minimize this risk, pediatric surgeons perform elective post-operative muscle paralysis, positive-pressure ventilation, and head flexion (PVF) to reduce movement and tension at the anastomosis. We systematically reviewed and analyzed the effect of post-operative PVF on reducing anastomotic complications. METHODS: Embase, MEDLINE, Web of Science, and PubMed databases were used to conduct searches. Articles reporting pediatric EA undergoing primary anastomosis, anastomotic complications, and comparisons between patients who received post-operative PVF to those who did not were included. Odds ratios (OR) for all post-operative anastomotic complications were calculated using random effects modelling. MAIN RESULTS: Three of the 2268 papers retrieved met inclusion criteria (all retrospective cohort studies). There were no randomized controlled trials. Post-operative PVF showed a significant reduction in anastomotic leak (OR 0.07; 95% CI 0.01-0.35) when compared to no PVF. Stricture formation was not statistically different between groups. Potential sources of bias include patient allocation. CONCLUSIONS: Based on available data, our analysis indicates PVF may reduce anastomotic post-operative leak. To confirm these results, a prospective study with clearer definitions of treatment allocation should be performed.

Phrenic Nerve Palsy Secondary to Parsonage-Turner Syndrome: A Diagnosis Commonly Overlooked.

Neuralgic Amyotrophy (NA) or Parsonage-Turner syndrome is an idiopathic neuropathy commonly affecting the brachial plexus. Associated phrenic nerve involvement, though recognised, is thought to be very rare. We present a case series of four patients (all male, mean age 53) presenting with dyspnoea preceded by severe self-limiting upper limb and shoulder pain, with an elevated hemi-diaphragm on clinical examination and chest X-ray. Neurological examination of the upper limb at the time of presentation was normal. Diaphragmatic fluoroscopy confirmed unilateral diaphragmatic paralysis. Pulmonary function testing demonstrated characteristic reduction in forced vital capacity between supine and sitting position (mean 50%, range 42-65% predicted, mean change 23%, range 22-46%), reduced maximal inspiratory pressures (mean 61%, range 43-86% predicted), reduced sniff nasal inspiratory pressure (mean 88.25, range 66-109 cm H2O) and preserved maximal expiratory pressure (mean 107%, range 83-130% predicted). Phrenic nerve conduction studies confirmed phrenic nerve palsy. All patients were managed conservatively. Follow-up ranged from 6 months to 3 years. Symptoms and lung function variables normalised in three patients and improved significantly in the fourth. The classic history of severe ipsilateral shoulder and upper limb neuromuscular pain should be elicited and thus NA considered in the differential for a unilateral diaphragmatic paralysis, even in the absence of neurological signs. Parsonage-Turner syndrome is likely to represent a significantly under-diagnosed aetiology of phrenic nerve palsy. Conservative management as opposed to surgical intervention is advocated as most patients demonstrate gradual resolution over time in this case series.

[Diagnosis and Treatment of Diaphragmatic Dysfunction]. / Diagnostik und Therapie der gestörten Zwerchfellfunktion.

There are many reasons for an impairment of the diaphragmatic function potentially affecting all components of the respiratory pump. Particularly, diagnosis and treatment of unilateral and bilateral phrenic nerve paralysis are challenging. Neuromuscular disorders, trauma, iatrogenic conditions, tumor compression, but also infectious and inflammatory conditions in addition to neuralgic amyotrophy and idiopathic phrenic nerve paralysis are reasons for phrenic nerve paralysis. Primarily, diagnostic procedures include the anamnesis, physical examination, blood gas analysis, lung function testing and the diagnosis of the underlying disease. In addition, specific respiratory muscle testing and respiratory imaging are available today. Current established treatment options include respiratory muscle training, long-term non-invasive ventilation and surgical diaphragm plication in selected patients.

Use of neuromuscular monitoring to detect prolonged effect of succinylcholine or mivacurium: three case reports.

Mutations in the butyrylcholinesterase gene can lead to a prolonged effect of the neuromuscular blocking agents, succinylcholine and mivacurium. If the anaesthesiologist is not aware of this condition, it may result in insufficient respiration after tracheal extubation. However, this can be avoided with the use of objective neuromuscular monitoring if used adequately. Three case reports of prolonged effect of succinylcholine or mivacurium were presented to illustrate the importance of neuromuscular monitoring during anaesthesia. In the first case, continuous intraoperative neuromuscular monitoring allowed a prolonged neuromuscular blockade to be discovered prior to tracheal extubation of the patient. The patient was extubated after successful reversal of the neuromuscular blockade. On the contrary, neuromuscular monitoring was not used during anaesthesia in the second patient; hence, the prolonged effect of the neuromuscular blocking agent was not discovered until after extubation. In the third patient, the lack of response to nerve stimulation was interpreted as a technical failure and the prolonged effect of succinylcholine was discovered when general anaesthesia was terminated. Both patients had insufficient respiration. They were therefore re-sedated, transferred to the intensive care unit and the tracheas were extubated after full recovery from neuromuscular blockade. We recommend the use of monitoring every time these agents are used, even with short-acting drugs like succinylcholine and mivacurium.

Comparison of three cough-augmentation techniques in neuromuscular patients: mechanical insufflation combined with manually assisted cough, insufflation-exsufflation alone and insufflation-exsufflation combined with manually assisted cough.

BACKGROUND: Mechanical insufflation-exsufflation (MI-E), more commonly known as 'cough assist therapy', is a method which produces inspiratory and expiratory assistance to improve cough performances. However, other alternatives or combinations are possible. OBJECTIVE: The objective was to compare the effects of mechanical insufflation combined with manually assisted coughing (MAC), insufflation-exsufflation alone and insufflation-exsufflation combined with MAC in neuromuscular patients requiring cough assistance. METHODS: Eighteen neuromuscular patients with severe respiratory muscle dysfunction and peak cough flow (PCF) lower than 3 liters/s or maximal expiratory pressure (MEP) lower than +45 cm H2O were studied. Patients were studied under three cough-assisted conditions, which were used in random order: insufflation by intermittent positive-pressure breathing (IPPB) combined with MAC, MI-E and MI-E + MAC. RESULTS: Overall, PCF was higher with IPPB + MAC than with MI-E + MAC or MI-E alone. Among the 12 patients who had higher PCF values with IPPB + MAC than with the two other techniques, 9 exhibited mask pressure swings during MI-E exsufflation, with a transient positive-pressure value due to the expiratory flow produced by the combined patient cough effort and MAC. Each of these 9 patients had higher PCF values (>5 liters/s) than did the other 9 patients when using IPPB + MAC. CONCLUSION: Our results indicate that adding the MI-E device to MAC is unhelpful in patients whose PCF with an insufflation technique and MAC exceeds 5 liters/s. This is because the expiratory flow produced by the patient's effort and MAC transitorily exceeds the vacuum capacity of the MI-E device, which therefore becomes a transient load against the PCF.

In a porcine model of implantable pacemakers for pediatric unilateral diaphragm paralysis, the phrenic nerve is the best target.

BACKGROUND: A frequent complication of Fontan operations is unilateral diaphragmatic paresis, which leads to hemodynamic deterioration of the Fontan circulation. A potential new therapeutic option is the unilateral diaphragmatic pacemaker. In this study, we investigated the most effective stimulation location for a potential fully implantable system in a porcine model. METHODS: Five pigs (20.8 ± 0.95 kg) underwent implantation of a customized cuff electrode placed around the right phrenic nerve. A bipolar myocardial pacing electrode was sutured adjacent to the motor point and peripherally at the costophrenic angle (peripheral diaphragmatic muscle). The electrodes were stimulated 30 times per minute with a pulse duration of 200 µs and a stimulation time of 300 ms. Current intensity was the only variable changed during the experiment. RESULTS: Effective stimulation occurred at 0.26 ± 0.024 mA at the phrenic nerve and 7 ± 1.22 mA at the motor point, a significant difference in amperage (p = 0.005). Even with a maximum stimulation of 10 mA at the peripheral diaphragm muscle, however, no effective stimulation was observed. CONCLUSION: The phrenic nerve seems to be the best location for direct stimulation by a unilateral thoracic diaphragm pacemaker in terms of the required amperage level in a porcine model.

Cervical Spine Stenosis Causing Diaphragmatic Paralysis: A Case Study and Narrative Review of Clinical Presentations and Outcomes.

STUDY DESIGN: Case report and narrative review. OBJECTIVE: To explore the therapeutic role of surgical and nonsurgical treatment of diaphragmatic paralysis secondary to spinal cord and nerve root compression. SUMMARY OF BACKGROUND DATA: Phrenic nerve dysfunction due to central or neuroforaminal stenosis is a rare yet unappreciated etiology of diaphragmatic paralysis and chronic dyspnea. Surgical spine decompression, diaphragmatic pacing, and intensive physiotherapy are potential treatment options with varying degrees of evidence. METHODS: The case of a 70-year-old male with progressive dyspnea, reduced hemi-diaphragmatic excursion, and C3-C7 stenosis, who underwent a microscopic foraminotomy is discussed. Literature review (MEDLINE, PubMed, Google Scholar) identified 19 similar reports and discussed alternative treatments and outcomes. RESULTS AND CONCLUSIONS: Phrenic nerve root decompression and improvement in neuromonitoring signals were observed intraoperatively. The patient's postoperative course was uncomplicated, and after 15 months, he experienced significant symptomatic improvement and minor improvement in hemi-diaphragmatic paralysis and pulmonary function tests. All case reports of patients treated with spinal decompression showed symptomatic and/or functional improvement, while one of the 2 patients treated with physiotherapy showed improvement. More studies are needed to further describe the course and outcomes of these interventions, but early identification and spinal decompression can be an effective treatment. OCEBM LEVEL OF EVIDENCE: Level-4.

Noninvasive respiratory management and diaphragm and electrophrenic pacing in neuromuscular disease and spinal cord injury.

The purpose of this monograph is to describe noninvasive management of respiratory muscle weakness/paralysis for patients with neuromuscular disease (NMD) and spinal cord injury (SCI). Noninvasive ventilation (NIV) assists and supports inspiratory muscles, whereas mechanically assisted coughing (MAC) simulates an effective cough. Long-term outcomes will be reviewed as well as the use of NIV, MAC, and electrophrenic pacing (EPP) and diaphragm pacing (DP) to facilitate extubation and decannulation. Although EPP and DP can facilitate decannulation and maintain alveolar ventilation for high-level SCI patients when they cannot use NIV because of lack of access to oral interfaces, there is no evidence that they have any place in the management of NMD.

Diaphragmatic paralysis: a rare consequence of dengue fever.

BACKGROUND: Dengue is considered one of the most common mosquito borne illnesses in the world. Although its clinical course is usually uneventful, complications have rarely been known to arise. These include neurological manifestations such as neuropathies. CASE PRESENTATION: We report a middle aged patient from urban Sri Lanka who developed diaphragmatic paralysis secondary to phrenic neuropathy a month after recovering from dengue fever. He was managed conservatively and made a full recovery subsequently. CONCLUSION: Isolated phrenic nerve palsy causing diaphragmatic paralysis should be considered a recognized complication of Dengue fever. A patient usually gains full recovery with conservative management.

Imaging of the diaphragm: anatomy and function.

The diaphragm is the primary muscle of ventilation. Dysfunction of the diaphragm is an underappreciated cause of respiratory difficulties and may be due to a wide variety of entities, including surgery, trauma, tumor, and infection. Diaphragmatic disease usually manifests as elevation at chest radiography. Functional imaging with fluoroscopy (or ultrasonography or magnetic resonance imaging) is a simple and effective method of diagnosing diaphragmatic dysfunction, which can be classified as paralysis, weakness, or eventration. Diaphragmatic paralysis is indicated by absence of orthograde excursion on quiet and deep breathing, with paradoxical motion on sniffing. Diaphragmatic weakness is indicated by reduced or delayed orthograde excursion on deep breathing, with or without paradoxical motion on sniffing. Eventration is congenital thinning of a segment of diaphragmatic muscle and manifests as focal weakness. Treatment of diaphragmatic paralysis depends on the cause of the dysfunction and the severity of the symptoms. Treatment options include plication and phrenic nerve stimulation. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.322115127/-/DC1.

Diaphragmatic paralysis among very low birth weight infants following ligation for patent ductus arteriosus.

Management of diaphragmatic paralysis (DP) among newborn infants remains controversial, especially for very low birth weight (VLBW) infants following ligation for patent ductus arteriosus (PDA). This study aimed to characterize the impact of DP after PDA ligation among VLBW infants. Clinical characteristics of DP cases treated with either diaphragmatic plication or conservative methods were described as well. The medical records of VLBW infants who underwent PDA ligation in Chang Gung Memorial Hospital between January 2000 and December 2011 were retrospectively reviewed, and DP was suspected if postligation chest X-rays showed an elevation of the left diaphragm as confirmed by a chest ultrasonograph. For each DP case, three other infants that received PDA ligation with proximate birth dates and who were closely matched in terms of gestational age (±1 week) and birth weight (±10 %) were selected as the control group. A total of eight preterm infants were diagnosed as having DP and 24 infants were selected as the control group. The affected infants usually presented with respiratory distress and extubation failure. The study demonstrated that, among our patient population, DP was associated with a significantly longer duration of ventilator dependency (56.1 ± 16.0 vs. 29.8 ± 17.7 days, p = 0.001) and a higher incidence of severe bronchopulmonary dysplasia (87.5 vs. 23 %, p = 0.002). For selective infants with DP-related ventilatory failure after PDA ligation, surgical plication may facilitate extubation. Diaphragmatic paralysis should be evaluated carefully among VLBW infants receiving PDA ligation because of its adverse impact on ventilator dependency and correlation to a higher incidence of severe bronchopulmonary dysplasia.

Electrophrenic pacing and decannulation for high-level spinal cord injury: a case series.

BACKGROUND: In 1997, guidelines were developed for the management of high-level ventilator-dependent patients with spinal cord injury who had little or no ventilator-free breathing ability (VFBA). This article describes the three categories of patients, the decannulation criteria, and the successful decannulation of four patients with no VFBA and electrophrenic/diaphragm pacing, using these criteria. METHOD: Case series. CONCLUSION: Lack of VFBA in patients with high-level spinal cord injury does not mandate tracheostomy or electrophrenic/diaphragm pacing.