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.

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.

High-flow nasal cannula oxygen therapy was effective for dysphagia associated with respiratory muscle paralysis due to cervical spinal cord injury: A case report.

RATIONALE: Respiratory muscle paralysis due to low cervical spinal cord injury (CSCI) can lead to dysphagia. Noninvasive positive airway pressure (PAP) therapy can effectively treat this type of dysphagia. High-flow nasal cannula (HFNC) oxygen therapy can generate a low level of positive airway pressure resembling PAP therapy, it may improve the dysphagia. PATIENT CONCERNS: The patient was an 87-year-old man without preexisting dysphagia. He suffered a CSCI due to a dislocated C5/6 fracture, without brain injury, and underwent emergency surgery. Postoperatively (day 2), he complained of dysphagia, and the intervention was initiated. DIAGNOSIS: Based on clinical findings, dysphagia in this case, may have arisen due to impaired coordination between breathing and swallowing, which typically occurs in patients with CSCI who have reduced forced vital capacity. INTERVENTIONS: HFNC oxygen therapy was started immediately after the surgery, and swallowing rehabilitation was started on Day 2. Indirect therapy (without food) and direct therapy (with food) were applied in stages. HFNC oxygen therapy appeared to be effective because swallowing function temporarily decreased when the HFNC oxygen therapy was changed to nasal canula oxygen therapy. OUTCOMES: Swallowing function of the patient improved and he did not develop aspiration pneumonia. LESSONS: HFNC oxygen therapy improved swallowing function in a patient with dysphagia associated with respiratory-muscle paralysis following a CSCI. It may have prolonged the apnea tolerance time during swallowing and may have improved the timing of swallowing. HFNC oxygen therapy can facilitate both indirect and direct early swallowing therapy to restore both swallowing and respiratory function.

Treatment for bilateral diaphragmatic dysfunction using phrenic nerve reconstruction and diaphragm pacemakers.

OBJECTIVES: Bilateral diaphragmatic dysfunction results in severe dyspnoea, usually requiring oxygen therapy and nocturnal ventilatory support. Although treatment options are limited, phrenic nerve reconstruction (PR) offers the opportunity to restore functional activity. This study aims to evaluate combination treatment with PR and placement of a diaphragm pacemaker (DP) compared to DP placement alone in patients with bilateral diaphragmatic dysfunction. METHODS: Patients with bilateral diaphragmatic dysfunction were prospectively enrolled in the following treatment algorithm: Unilateral PR was performed on the more severely impacted side with bilateral DP implantation. Motor amplitudes, ultrasound measurements of diaphragm thickness, maximal inspiratory pressure, forced expiratory volume, forced vital capacity and subjective patient-reported outcomes were obtained for retrospective analysis following completion of the prospective database. RESULTS: Fourteen male patients with bilateral diaphragmatic dysfunction confirmed on chest fluoroscopy and electrodiagnostic testing were included. All 14 patients required nocturnal ventilator support, and 8/14 (57.1%) were oxygen-dependent. All patients reported subjective improvement, and all 8 oxygen-dependent patients were able to discontinue oxygen therapy following treatment. Improvements in maximal inspiratory pressure, forced vital capacity and forced expiratory volume were 68%, 47% and 53%, respectively. There was an average improvement of 180% in motor amplitude and a 50% increase in muscle thickness. Comparison of motor amplitude changes revealed significantly greater functional recovery on the PR + DP side. CONCLUSIONS: PR and simultaneous implantation of a DP may restore functional activity and alleviate symptoms in patients with bilateral diaphragmatic dysfunction. PR plus diaphragm pacing appear to result in greater functional muscle recovery than pacing alone.

Spinal cord injury level and Phrenic Nerve Conduction Studies do not predict diaphragm pacing success or failure- all patients should undergo diagnostic laparoscopy.

BACKGROUND: Diaphragm Pacing(DP) demonstrates benefits over mechanical ventilation(MV) for spinal cord injured(SCI) patients. The hypothesis of this report is that phrenic nerve conduction study(PNCS) results cannot differentiate success or failure in selection of patients for DP. Direct surgical evaluation of the diaphragm should be performed. METHODS: Observational report of prospective databases of patients undergoing laparoscopic evaluation of their diaphragms to assess for ability to stimulate to cause contraction for ventilation. RESULTS: In 50 SCI patients who could not be weaned from MV, PNCS results showed latencies in stimulated patients (n = 44) and non-stimulated(n = 6) overlapped (7.8 ± 2.5 ms vs 9.4 ± 2.8 ms) and the null hypothesis cannot be rejected (p-value>0.05). Amplitudes overlapped (0.4 ± 0.2 mV vs 0.2 ± 0.2 mV) and the null hypotheses cannot be rejected (P-value >0.05). In 125 non SCI patients with diaphragm paralysis, there were 78(62.4%) with false negative PNCS. CONCLUSION: PNCS are inadequate pre-operative studies. Direct laparoscopic evaluation should be offered for all SCI patients to receive the benefit of DP.

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.

Diaphragmatic paralysis after phrenic nerve injury in newborns.

BACKGROUND: Phrenic nerve injury (PNI) from birth trauma is a recognized phenomenon, generally occurring with ipsilateral brachial plexus palsy (BPP). In severe cases, PNI results in diaphragm paresis (DP) and respiratory insufficiency. Surgical diaphragmatic plication (SDP) is a potential management strategy for patients with PNI and DP, but timing and outcomes associated with SDP have not been rigorously studied. METHODS: Records from 49 tertiary United States pediatric hospitals in the Pediatric Health Information System from 2004 to 2018 were analyzed. The study cohort included patients diagnosed with BPP from birth trauma who were documented to have PNI or DP. Patients who underwent congenital cardiac operations were excluded. RESULTS: A total of 5832 patients were identified with BPP from birth trauma during the study period, 122 (2%) of whom were found to have concomitant DP. Of those, 65 (53%) were male, 39 (32%) were infants of diabetic mothers, 80 (65%) required mechanical ventilation, and 33 (27%) underwent SDP. SDP was performed at a median (range) age of 36 (7-95) days. Median (range) total and postoperative hospital lengths of stay (LOS) were 34 (6-180) and 15 (4-132) days, respectively. There was also an observed increase in post-operative LOS with increase in age at operation. CONCLUSION: Neonatal DP is rare and is managed with SDP in a minority of instances. Age at repair affects total and postoperative length of stay, proxies for resource utilization and morbidity. Repair prior to 45 days of life appears to result in a shorter postoperative hospital stay. This analysis will help guide surgeons with respect to indications and operative timing for infant DP. TYPE OF STUDY: Retrospective Comparative Study. LEVEL OF EVIDENCE: Level III.

Diaphragmatic paralysis in young children: A literature review.

Diaphragmatic paralysis (DP) is a rare cause of respiratory distress in young children. In the first years of life, the main cause is phrenic nerve injury after cardiothoracic surgery or obstetrical trauma. DP usually presents as respiratory distress. Asymmetrical thorax elevation, difficulty weaning from mechanical ventilation, pulmonary atelectasis, and repeated pulmonary infections are other suggestive signs or complications. DP is usually suspected on chest X-ray showing abnormal hemidiaphragm elevation. Although fluoroscopy was considered the gold standard for DP confirmation, it has gradually been replaced by ultrasound, which can be done at the bedside. Some electrophysiological tools may be useful for a better characterization of phrenic nerve injury and chance of recovery. The management of DP is mainly based on clinical severity. In mild asymptomatic cases, DP may only require close monitoring. In more severe cases, adequate ventilatory support and/or surgical diaphragmatic plication may be needed. Electrophysiological tools may help clinicians assess the ideal timing for diaphragmatic plication.

Disfunción de marcapasos diafragmático y utilidad de la ecografía diafragmática / Diaphragmatic pacemaker dysfunction and utility of diaphragmatic ultrasonography

Los pacientes con lesiones medulares por encima de C5 presentan un alto riesgo de complicaciones respiratorias y en el caso de las lesiones medulares completas la mayoría requerirán soporte con ventilación mecánica de forma permanente. En pacientes seleccionados el implante de un marcapasos diafragmático ofrece la posibilidad de respirar sin soporte mecánico y representa una reducción de complicaciones respiratorias proporcionando al paciente mayor independencia. La ecografía supone una técnica sencilla y no invasiva que puede ser útil para el diagnóstico diferencial de patología torácica. Presentamos el caso de un paciente con lesión medular cervical traumática, al que le fue implantado un marcapasos diafragmático y en el que el uso de la ecografía permitió un diagnóstico rápido y fiable de una disfunción del dispositivo. La ecografía diafragmática en modo M es una técnica sencilla y no invasiva que se puede incorporar en la práctica clínica habitual para diagnosticar trastornos del movimiento del diafragma

Patients with spinal cord injuries above the C5 vertebrae have a high risk of respiratory complications, and complete spinal cord injures can require support with mechanical ventilation. In selected patients, implantation of a diaphragmatic pacemaker offers the possibility of breathing without mechanical support and reduces respiratory complications, increasing the patient's independence. Ultrasonography is a simple and non-invasive technique that may be useful in the differential diagnosis of thoracic diseases. We present the case of a patient with a traumatic cervical spinal cord injury, who underwent diaphragmatic pacemaker implantation. The use of ultrasound allowed rapid and reliable diagnosis of device malfunction. M-mode diaphragmatic ultrasonography is a simple and non-invasive technique that can be incorporated into routine clinical practice to diagnose diaphragm movement disorders

[Diaphragm pacemaker: alternative for long-term ventilatory support; 5 years later]. / Diafragmapacemaker: alternatief voor chronische beademing.

Currently, more than 3000 patients in the Netherlands receive long-term ventilatory support. In the majority of patients, long-term ventilatory support leads to increased survival without any complications. Diaphragm pacing with an external pacemaker (diaphragm pacing system, DPS) seems an attractive alternative for long-term ventilatory support by mask or tracheostomy. Scientific research has since shown that DPS is effective in patients with high cervical paraplegia. In addition, patients with congenital central hypoventilation syndrome are also eligible for DPS. Patients with diaphragm paralysis are a new group of patients who may be eligible for DPS. Two European studies have shown that DPS should not be used in patients with amyotrophic lateral sclerosis. In our experience, patients are no longer completely dependent on a ventilator or may even be able to discontinue using one if the procedure was successful. In the Netherlands, as far as we know, the technique is only used at the University Medical Center Groningen.