Safety and efficacy of diaphragm pacing in patients with respiratory insufficiency due to amyotrophic lateral sclerosis (DiPALS): a multicentre, open-label, randomised controlled trial

Recent advances in amyotrophic lateral sclerosis

ALS is a relentlessly progressive and fatal disease, with no curative therapies available to date. Symptomatic and palliative care, provided in a multidisciplinary context, still remains the cornerstone of ALS management. However, our understanding of the molecular mechanisms underlying the disease has advanced greatly over the past years, giving new hope for the development of novel diagnostic and therapeutic approaches. Here, we have reviewed the most recent studies that have contributed to improving both clinical management and our understanding of ALS pathogenesis.

Diaphragm pacing: the state of the art

Diaphragm pacing (DP) is an orphan surgical procedure that may be proposed in strictly selected ventilator-dependent patients to get an active diaphragm contraction. The goal is to wean from mechanical ventilation (MV) and restore permanent efficient breathing. The two validated indications, despite the lack of randomised control trials, concern patients with high-level spinal cord injuries (SCI) and central hypoventilation syndromes (CHS). To date, two different techniques exist. The first, intrathoracic diaphragm pacing (IT-DP), based on a radiofrequency method, in which the electrodes are directly placed around the phrenic nerve. The second, intraperitoneal diaphragm pacing (IP-DP) uses intradiaphragmatic electrodes implanted through laparoscopy. In both techniques, the phrenic nerves must be intact and diaphragm reconditioning is always required after implantation. No perioperative mortality has been reported and ventilator-weaning rate is about 72% to 96% in both techniques. Improvement of quality of life, by restoring a more physiological breathing, has been almost constant in patients that could be weaned. Failure or delay in recovery of effective diaphragm contractions could be due to irreversible amyotrophy or chest wall damage. Recent works have evaluated the interest of IP-DP in amyotrophic lateral sclerosis (ALS). After some short series were reported in the literature, the only multicentric randomized study including 74 ALS patients was prematurely stopped because of excessive mortality in paced patients. Then, another trial analysed the place of IP-DP in peripheral diaphragm dysfunction but, given the multiple biases, the published results cannot validate that indication. Reviewing all available literature as in our experience, shows that DP is an effective method to wean selected patients dependent on ventilator and improve their daily life. Other potential indications will have to be evaluated by randomised control trials.

Practical respiratory management in amyotrophic lateral sclerosis: evidence, controversies and recent advances

In amyotrophic lateral sclerosis, the onset of respiratory muscle weakness is silent, but survival following symptom recognition may only be a few weeks. Consequently, respiratory function and symptoms should be assessed every 2-3 months. Noninvasive ventilation improves symptoms, quality of life and survival, without increasing carer burden. Lung volume recruitment helps to reverse and prevent atelectasis, improving gas exchange, while techniques to enhance sputum clearance reduce the risk of mucus plugging and lower respiratory tract infections. When noninvasive support fails, often due to severe bulbar impairment, tracheostomy ventilation prolongs life. Most patients receiving tracheostomy ventilation at home report satisfactory quality of life, but at the expense of high carer burden. Diaphragmatic pacing is associated with an increased risk of death.

Restoring motor function using optogenetics and neural engraftment

Controlling muscle function is essential for human behaviour and survival, thus, impairment of motor function and muscle paralysis can severely impact quality of life and may be immediately life-threatening, as occurs in many cases of traumatic spinal cord injury (SCI) and in patients with amyotrophic lateral sclerosis (ALS). Repairing damaged spinal motor circuits, in either SCI or ALS, currently remains an elusive goal. Therefore alternative strategies are needed to artificially control muscle function and thereby enable essential motor tasks. This review focuses on recent advances towards restoring motor function, with a particular focus on stem cell-derived neuronal engraftment strategies, optogenetic control of motor function and the potential future translational application of these approaches.

Intramuscular diaphragmatic stimulation for patients with traumatic high cervical injuries and ventilator dependent respiratory failure: A systematic review of safety and effectiveness

BACKGROUND

Intramuscular diaphragmatic stimulation using an abdominal laparoscopic approach has been proposed as a safer alternative to traditional phrenic nerve stimulation. It has also been suggested that early implementation of diaphragmatic pacing may prevent diaphragm atrophy and lead to earlier ventilator independence. The aim of this study was therefore to systematically review the safety and effectiveness of intramuscular diaphragmatic stimulators in the treatment of patients with traumatic high cervical injuries resulting in long-term ventilator dependence, with particular emphasis on the affect of timing of insertion of such stimulators.

METHODS

The Cochrane database and PubMed were searched between January 2000 and June 2015. Reference lists of selected papers were also reviewed. The inclusion criteria used to select from the pool of eligible studies were: (1) reported on adult patients with traumatic high cervical injury, who were ventilator-dependant, (2) patients underwent intramuscular diaphragmatic stimulation, and (3) commented on safety and/or effectiveness.

RESULTS

12 articles were included in the review. Reported safety issues post insertion of intramuscular electrodes included pneumothorax, infection, and interaction with pre-existing cardiac pacemaker. Only one procedural failure was reported. The percentage of patients reported as independent of ventilatory support post procedure ranged between 40% and 72.2%. The mean delay of insertion ranged from 40 days to 9.7 years; of note the study with the average shortest delay in insertion reported the greatest percentage of fully weaned patients.

CONCLUSIONS

Although evidence for intramuscular diaphragmatic stimulation in patients with high cervical injuries and ventilator dependent respiratory failure is currently limited, the technique appears to be safe and effective. Earlier implantation of such devices does not appear to be associated with greater surgical risk, and may be more effective. Further high quality studies are warranted to investigate the impact of delay of insertion on ventilator weaning.

Implantable Devices: Assessment and Perioperative Management

Technology is the prominent feature of the twenty-first century, including in medicine. There are very few organs that cannot be stimulated, shocked, or infused. With more and more implantable devices being approved for clinical use, anesthesiologists have to regularly take care of patients who have these devices. An understanding of the devices, the associated comorbidities, and the perioperative risks is crucial for safe management of these patients. Cardiac devices are discussed in some detail; neurostimulators and other implantable devices are briefly described. The principles of assessment and management are similar for all patients with implanted devices.

Update on clinical trials in home mechanical ventilation

Home mechanical ventilation (HMV) is an increasingly common intervention and is initiated for a range of pathological processes, including neuromuscular disease (NMD), chronic obstructive pulmonary disease (COPD) and obesity related respiratory failure. There have been important recent data published in this area, which helps to guide practice by indicating which populations may benefit from this intervention and the optimum method of setting up and controlling sleep disordered breathing. Recent superficially conflicting data has been published regarding HMV in COPD, with a trial in post-exacerbation patients suggesting no benefit, but in stable chronic hypercapnic patients suggesting a clear and sustained mortality benefit. The two studies are critiqued and the potential reasons for the differing results are discussed. Early and small trial data is frequently contradicted with larger randomised controlled trials and this has been the case with diaphragm pacing being shown to be potentially harmful in the latest data, confirming the importance of non-invasive ventilation (NIV) in NMD such as motor neurone disease. Advances in ventilator technology have so far appeared quicker than the clinical data to support their use; although small and often unblinded, the current data suggests equivalence to standard modes of NIV, but with potential comfort benefits that may enhance adherence. The indications for NIV have expanded since its inception, with an effort to treat sleep disordered breathing as a result of chronic heart failure (HF). The SERVE-HF trial has recently demonstrated no clear advantage to this technology and furthermore detected a potentially deleterious effect, with a worsening of all cause and cardiovascular mortality in the treated group compared to controls. The review serves to provide the reader with a critical review of recent advances in the field of sleep disordered breathing and HMV.

An Autopsy Case of Amyotrophic Lateral Sclerosis with Diaphragm Pacing

Respiratory insufficiency is a critical problem in amyotrophic lateral sclerosis (ALS) patients. We herein present the case of an autopsied patient with sporadic ALS who underwent diaphragm pacing (DP). The pathology showed several localized adhesions with a markedly atrophied diaphragm. A marked loss of motor neurons with Bunina bodies and phosphorylated TDP-43 positive inclusions was found in the spinal cord and primary motor cortex. Mild hyalinization and a few multinucleated giant cells were present around the electrode tracks in the diaphragm. However, no infiltration of inflammatory cells was detected. Our findings suggest that full-time DP might not cause severe damage to adjacent diaphragm tissue.

Diaphragm pacing and motor neurone disease: lessons for all?

Respiratory muscle involvement is inevitable in motor neurone disease (MND) and most patients will die a respiratory death. Noninvasive ventilation (NIV) has been shown to prolong life and improve quality of life [1]. It is therefore important to identify patients who should be offered NIV at an early stage, as a delay may result in presentation with catastrophic respiratory failure, requiring endotracheal intubation, which almost always results in an unplanned tracheostomy. It used to be considered that respiratory muscle involvement was only a feature of advanced disease, but this is not correct; if looked for there is evidence of respiratory muscle weakness in most patients by the time the diagnosis is made [2]. In a small number, the diagnosis is made when the patient presents with hypercapnic respiratory failure.

Respiratory physicians and neurologists should be cognisant of the respiratory complications of motor neurone diseasehttp://ow.ly/TIxe5