Duchenne Muscular Dystrophy: Life Prolongation by Noninvasive Ventilatory Support

Derivation and validation of diagnostic models for myocardial fibrosis in duchenne muscular dystrophy: assessed by multi-parameter cardiovascular magnetic resonance

BACKGROUND

Gadolinium-enhanced cardiovascular magnetic resonance (CMR) is the most widely used approach for diagnosing myocardial fibrosis with late gadolinium enhancement (LGE) in cardiomyopathy associated with Duchenne muscular dystrophy. Given the limitations and safety of gadolinium use, we wanted to develop and evaluate multi-parametric pre-contrast CMR models for the diagnosis of LGE and investigate whether they could be utilised as surrogates for LGE in DMD patients.

METHODS

A total of 136 DMD patients were prospectively recruited and separated into LGE - and LGE + groups. In the first subset of patients (derivation cohort), regression models for the diagnosis of LGE were built by logistic regression using pre-contrast sequence parameters. In a validation cohort of other patients, the models' performances were evaluated.

RESULTS

EF, native T1 and longitudinal strain alone, as well as their combinations form seven models. The model that included EF, native T1 and longitudinal strain had the best diagnostic value, but there was no significant difference in diagnostic accuracy among the other models except EF. In the validation cohort, the diagnosis outcomes of models were moderate consistent with the existence of LGE. The longitudinal strain outperformed the other models in terms of diagnostic value (sensitivity: 83.33%, specificity: 54.55%).

CONCLUSIONS

Pre-contrast sequences have a moderate predictive value for LGE. Thus, pre-contrast parameters may be considered only in a specific subset of DMD patients who cannot cooperate for long-time examinations and have contradiction of contrast agent to help predict the presence of LGE.

TRIAL REGISTRATION NUMBER (TRN)

ChiCTR1800018340 DATE OF REGISTRATION: 20180107.

Prognostic factors, disease course, and treatment efficacy in Duchenne muscular dystrophy: A systematic review and meta-analysis

INTRODUCTION/AIMS

Prognostic factors in Duchenne muscular dystrophy (DMD) predict the disease course and may help individualize patient care. The aim was to summarize the evidence on prognostic factors that may support treatment decisions.

METHODS

We searched six databases for prospective studies that each included ≥50 DMD patients with a minimum follow-up of 1 y. Primary outcomes were age at loss of ambulation (LoA), pulmonary function (forced vital capacity percent of predicted, FVC%p), and heart failure.

RESULTS

Out of 5074 references, 59 studies were analyzed. Corticosteroid use was associated with a delayed LoA (pooled effect hazard ratio [HR] 0.42, 95% confidence interval [CI] 0.23-0.75, I2 94%), better pulmonary function tests (higher peak FVC%, prolonged time with FVC%p > 50%, and reduced need for assisted ventilation) and delayed cardiomyopathy. Longer corticosteroid treatment was associated with later LoA (>1 y compared to <1 y; pooled HR: 0.50, 95% CI 0.27-0.90) and early treatment start (aged <5 y) may be associated with early cardiomyopathy and higher fracture risk. Genotype appeared to be an independent driver of LoA in some studies. Higher baseline physical function tests (e.g., 6-minute walk test) were associated with delayed LoA. Left ventricular dysfunction and FVC <1 L increased and the use of angiotensin-converting enzyme (ACE) inhibitors reduced the risk of heart failure and death. Fusion surgery in scoliosis may potentially preserve pulmonary function.

DISCUSSION

Prognostic factors that may inform clinical decisions include age at corticosteroid treatment initiation and treatment duration, ACE-inhibitor use, baseline physical function tests, pulmonary function, and cardiac dysfunction.

Practice recommendations for the role of physiotherapy in the management of sleep disorders: the 2022 Brazilian Sleep Association Guidelines

This clinical guideline supported by the Brazilian Sleep Association comprises a brief history of the development of Brazilian sleep physiotherapy, outlines the role of the physiotherapist as part of a sleep health team, and describes the clinical guidelines in respect of the management of some sleep disorders by the physiotherapist (including sleep breathing disorders, i.e., obstructive sleep apnea, central sleep apnea, upper airway resistance syndrome, hypoventilation syndromes and overlap syndrome, and pediatric sleep breathing disorders; sleep bruxism; circadian rhythms disturbances; insomnia; and Willis-Ekbom disease/periodic limb movement disorder. This clinical practice guideline reflects the state of the art at the time of publication and will be reviewed and updated as new information becomes available.

Early NIV is associated with accelerated lung function decline in Duchenne muscular dystrophy treated with glucocorticosteroids

Background

Use of non-invasive ventilation (NIV) in adolescents with Duchenne muscular dystrophy (DMD) has increased with concomitant extended survival.

Aim

To describe lung function (LF) changes with NIV in adolescents with DMD and to assess differences between Steroid Users and Steroid Naïve subjects.

Method

A retrospective cohort of adolescents with DMD initiating NIV over 10 years was conducted. Serial LF before and after NIV initiation was collated. Use of systemic glucocorticosteroids, adherence to NIV and presence of cardiac disease were assessed.

Results

Twenty-nine men started NIV, median age 14.66 years (IQR 2.35, 10.47–17.96). Nine were Steroid Users and eight were Steroid Naïve. Indications for NIV were apnoea–hypopnoea index >5 and/or nocturnal hypoventilation. LF is better (forced vital capacity (FVC) z-score −3.26 vs −5.41, p < 0.02) and decline slower (FVC z-score −0.58 per annum (pa) vs −0.68 pa, p<0.001) in Steroid Users compared with Steroid Naïve subjects. Following NIV initiation, FVC z-score decline slowed for the whole (−0.72 pa (95% CI −0.79 to 0.64) to −0.46 pa (95% CI −0.54 to 0.38) p < 0.001) and Steroid Naïve groups (−0.74 (95% CI −0.85 to 0.63) to −0.44 pa (95% CI −0.56 to 0.32) p < 0.001) but accelerated in the Steroid User group (−0.56 (95% CI −0.70 to 0.42) to −0.75 pa (95% CI −0.89 to 0.61) p < 0.001). Adherence to NIV and cardiac disease did not impact decline.

Conclusion

Overall, LF decline is reduced on NIV. Steroid Naïve patients have lower LF and faster decline, which slows following NIV initiation. An accelerated LF decline was seen on NIV in Steroid Users which requires further prospective research.

Neuromuscular Respiratory Failure

Neuromuscular respiratory failure can result from any disease that causes weakness of bulbar and/or respiratory muscles. Once compensatory mechanisms are overwhelmed, hypoxemic and hypercapnic respiratory failure ensues. The diagnosis of neuromuscular respiratory failure is primarily clinical, but arterial blood gases, bedside spirometry, and diaphragmatic ultrasonography can help in early assessment. Intensive care unit (ICU) admission is indicated for patients with severe bulbar weakness or rapidly progressing appendicular weakness. Intubation should be performed electively, particularly in patients with dysautonomia. Patients with an underlying treatable cause have the potential to regain functional independence with meticulous ICU care.

Liberation and mortality outcomes in pediatric long-term ventilation: A qualitative systematic review

OBJECTIVE

To provide a systematic review of liberation from positive pressure ventilation and mortality of children with chronic respiratory failure who used long-term invasive and noninvasive ventilation (LTV).

METHODS

Papers published from 1980 to 2018 were identified using Pubmed MEDLINE, Ovid MEDLINE, Embase, and Cochrane databases. Search results were limited to English-language papers with (a) patients less than 22 years at initiation, (b) patients who used invasive ventilation (IV) via tracheostomy or noninvasive ventilation (NIV), and (c) data on mortality or liberation from LTV. Data were presented using descriptive statistics; changes in outcomes over time were explored using linear regression. Follow-up variability, cohort heterogeneity, and insufficient data precluded combining data to estimate incidences or rates.

RESULTS

One hundred and thirty papers with 12 704 patients were included. The median number of patients was 37 (interquartile range [IQR] 17-74, range 6-3802). Twenty-five percent of patients were initiated on IV; 75% on NIV. The maximum follow-up ranged from 0.5 to 31.8 years (median 8.8 years). The median proportion of patients liberated in these papers was 3% (IQR 0%-21%). The median proportion of mortality was 18% (IQR 8%-27%). Proportions of liberation and mortality did not significantly change over time. Progression of underlying disease (44%), respiratory illness (19%), and LTV accident (11%) were the most common causes of death.

CONCLUSIONS

These papers collectively show most patients survive for many years using LTV; in many subgroups, death is a more common outcome than liberation. However, the limitations of these papers preclude robust prognostication.

Glucocorticoid-Associated Demise of a Patient With Duchenne Muscular Dystrophy

We describe the clinical deterioration of a 26-yr-old man with Duchenne muscular dystrophy on oral daily high-dose deflazacort. Although this daily regimen was targeted to benefit ambulation and respiration, it resulted in premature death with lethal sequelae from liver failure, decubiti, diabetes mellitus, and morbid obesity. This case illustrates the need for further research weighing risk versus benefit of daily glucocorticoid therapy, specifically deflazacort, in Duchenne muscular dystrophy patients. Thus, curtailment of daily dosing to eliminate dire sequelae in patients living longer into adulthood than ever before is recommended.

Daytime noninvasive ventilatory support for patients with ventilatory pump failure: a narrative review

Over the past three decades, the use of noninvasive ventilation or "NIV" to assuage symptoms of hypoventilation for patients with early onset or mild ventilatory pump failure has been extended to up to the use of continuous noninvasive ventilatory support (CNVS) at full ventilatory support settings as a definitive alternative to tracheostomy mechanical ventilation. NVS, along with mechanical insufflation-exsufflation, now provides a noninvasive option for the management of both chronic and acute respiratory failure for these patients. The most common diagnoses for which these methods are useful include chest wall deformities, neuromuscular diseases, morbid obesity, high level spinal cord injury and idiopathic, primary or secondary disorders of the ventilatory control. Thus, NVS is being used in diverse settings: critical care units, medical wards, at home, and in extended care. The aim of this review is to examine the techniques used for daytime support.

Renal involvement in the pathogenesis of mineral and bone disorder in dystrophin-deficient mdx mouse

Duchenne muscular dystrophy is a severe muscular disorder, often complicated with osteoporosis, and impaired renal function has recently been featured. We aimed to clarify the involvement of renal function in the pathogenesis of mineral and bone disorder in mdx mice, a murine model of the disease. We clearly revealed renal dysfunction in adult mdx mice, in which dehydration and hypercalcemia were contributed. We also examined the effects of dietary phosphorus (P) overload on phosphate metabolism. Serum phosphate and parathyroid hormone (PTH) levels were significantly increased in mdx mice by dietary P in a dose-dependent manner; however, bone alkaline phosphatase levels were significantly lower in mdx mice. Additionally, bone mineral density in mdx mice were even worsened by increased dietary P in a dose-dependent manner. These results suggested that the uncoupling of bone formation and resorption was enhanced by skeletal resistance to PTH due to renal failure in mdx mice.

Intensive Care Management of the Neuromuscular Patient

Neuromuscular emergencies are a distinct group of acute neurological diseases with distinct characteristic presentations. Patients who suffer from this group of diseases are at immediate risk of losing protection of their native airway as well as aspirating orogastric contents. This is secondary to weakness of the muscles of the oropharynx and respiratory muscles. Although some neuromuscular emergencies such as myasthenia gravis or Guillain-Barré syndrome are well understood, others such as critical illness myopathy and neuropathy are less well characterized. In this chapter, we have discussed the pathophysiology, diagnostic evaluation, and management options in patients who are admitted to the intensive care unit. We have also emphasized the importance of a thorough understanding of the use of pharmacological anesthetic agents in this patient population.

Primary Acute Neuromuscular Respiratory Failure

Neurologists are often called to evaluate patients with both defined and undiagnosed neuromuscular disorders when respiratory failure develops to determine if there is a neuromuscular cause. Being able to confidently diagnose neuromuscular respiratory failure and intervene appropriately is imperative, as early intervention and determination of the cause have survival implications. Outcomes are poor when the cause of neuromuscular weakness and resultant respiratory failure cannot be identified. This review discusses the clinical recognition of primary neuromuscular respiratory failure, its pathophysiology, diagnostic evaluation, and management, focusing on management of respiratory failure in the setting of Guillain-Barré syndrome and myasthenic crisis.

Current and Emerging Therapies for Duchenne Muscular Dystrophy

PURPOSE OF REVIEW

The purpose of this review is to summarize the current and emerging therapies for Duchenne muscular dystrophy (DMD).

RECENT FINDINGS

Coinciding with new standardized care guidelines, there are a growing number of therapeutic options to treat males with DMD. Treatment of the underlying pathobiology, such as micro-dystrophin gene replacement, exon skipping, stop codon read-through agents, and utrophin modulators showed variable success in animal and human studies. Symptomatic therapies to target muscle ischemia, enhance muscle regeneration, prevent muscle fibrosis, inhibit myostatin, and reduce inflammation are also under investigation. DMD is a complex, heterogeneous degenerative disease. The pharmacological and technological achievements made in recent years, plus timely supportive interventions will likely lead to an improved quality of life for many individuals with DMD.

Cardiac function associated with home ventilator care in Duchenne muscular dystrophy

Purpose

Cardiomyopathy is becoming the leading cause of death in patients with Duchenne muscular dystrophy because mechanically assisted lung ventilation and assisted coughing have helped resolve respiratory complications. To clarify cardiopulmonary function, we compared cardiac function between the home ventilator-assisted and non-ventilator-assisted groups.

Methods

We retrospectively reviewed patients with Duchenne muscular dystrophy from January 2010 to March 2016 at Gangnam Severance Hospital. Demographic characteristics, pulmonary function, and echocardiography data were investigated.

Results

Fifty-four patients with Duchenne muscular dystrophy were divided into 2 groups: home ventilator-assisted and non-ventilator-assisted. The patients in the home ventilator group were older (16.25±1.85 years) than those in the nonventilator group (14.73±1.36 years) (P=0.001). Height, weight, and body surface area did not differ significantly between groups. The home ventilator group had a lower seated functional vital capacity (1,038±620.41 mL) than the nonventilator group (1,455±603.12 mL). Mean left ventricular ejection fraction and fractional shortening were greater in the home ventilator group, but the data did not show any statistical difference. The early ventricular filling velocity/late ventricular filling velocity ratio (1.7±0.44) was lower in the home ventilator group than in the nonventilator group (2.02±0.62). The mitral valve annular systolic velocity was higher in the home ventilator group (estimated β, 1.06; standard error, 0.48). Patients with Duchenne muscular dystrophy on a ventilator may have better systolic and diastolic cardiac functions.

Conclusion

Noninvasive ventilator assistance can help preserve cardiac function. Therefore, early utilization of noninvasive ventilation or oxygen may positively influence cardiac function in patients with Duchenne muscular dystrophy.

Respiratory failure because of neuromuscular disease

PURPOSE OF REVIEW

Understanding the mechanisms and abnormalities of respiratory function in neuromuscular disease is critical to supporting the patient and maintaining ventilation in the face of acute or chronic progressive impairment.

RECENT FINDINGS

Retrospective clinical studies reviewing the care of patients with Guillain-Barré syndrome and myasthenia have shown a disturbingly high mortality following step-down from intensive care. This implies high dependency and rehabilitation management is failing despite evidence that delayed improvement can occur with long-term care. A variety of mechanisms of phrenic nerve impairment have been recognized with newer investigation techniques, including EMG and ultrasound. Specific treatment for progressive neuromuscular and muscle disease has been increasingly possible particularly for the treatment of myasthenia, metabolic myopathies, and Duchenne muscular dystrophy. For those conditions without specific treatment, it has been increasingly possible to support ventilation in the domiciliary setting with newer techniques of noninvasive ventilation and better airway clearance. There remained several areas of vigorous debates, including the role for tracheostomy care and the place of respiratory muscle training and phrenic nerve/diaphragm pacing.

SUMMARY

Recent studies and systematic reviews have defined criteria for anticipating, recognizing, and managing ventilatory failure because of acute neuromuscular disease. The care of patients requiring long-term noninvasive ventilatory support for chronic disorders has also evolved. This has resulted in significantly improved survival for patients requiring domiciliary ventilatory support.

Sleep Disorders in Childhood Neurogenetic Disorders

enetic advances in the past three decades have transformed our understanding and treatment of many human diseases including neurogenetic disorders. Most neurogenetic disorders can be classified as "rare disease," but collectively neurogenetic disorders are not rare and are commonly encountered in general pediatric practice. The authors decided to select eight relatively well-known neurogenetic disorders including Down syndrome, Angelman syndrome, Prader-Willi syndrome, Smith-Magenis syndrome, congenital central hypoventilation syndrome, achondroplasia, mucopolysaccharidoses, and Duchenne muscular dystrophy. Each disorder is presented in the following format: overview, clinical characteristics, developmental aspects, associated sleep disorders, management and research/future directions.

Noninvasive Respiratory Management of Patients With Neuromuscular Disease

This review article describes definitive noninvasive respiratory management of respiratory muscle dysfunction to eliminate need to resort to tracheotomy. In 2010 clinicians from 22 centers in 18 countries reported 1,623 spinal muscular atrophy type 1 (SMA1), Duchenne muscular dystrophy (DMD), and amyotrophic lateral sclerosis users of noninvasive ventilatory support (NVS) of whom 760 required it continuously (CNVS). The CNVS sustained their lives by over 3,000 patient-years without resort to indwelling tracheostomy tubes. These centers have now extubated at least 74 consecutive ventilator unweanable patients with DMD, over 95% of CNVS-dependent patients with SMA1, and hundreds of others with advanced neuromuscular disorders (NMDs) without resort to tracheotomy. Two centers reported a 99% success rate at extubating 258 ventilator unweanable patients without resort to tracheotomy. Patients with myopathic or lower motor neuron disorders can be managed noninvasively by up to CNVS, indefinitely, despite having little or no measurable vital capacity, with the use of physical medicine respiratory muscle aids. Ventilator-dependent patients can be decannulated of their tracheostomy tubes.

Mouthpiece ventilation and complementary techniques in patients with neuromuscular disease: A brief clinical review and update

Noninvasive ventilatory support (NVS) is sometimes reported as suboptimal in patients with neuromuscular disease (NMD). The reasons for this include inadequate ventilator settings and/or lack of interface tolerance. NVS has been used for many years in patients with NMD disorders as a viable alternative to continuous ventilatory support via a tracheostomy tube. The mouthpiece ventilation (MPV) is a ventilatory mode that is used as daytime ventilatory support in combination with other ventilatory modalities and interfaces for nocturnal NVS. However, there is still a poor understanding of this method's benefits compared with other modalities. This review aims to highlight the indications and advantages along with the disadvantages of MPV.

Perceived quality of life among caregivers of children with a childhood-onset dystrophinopathy: a double ABCX model of caregiver stressors and perceived resources

Background

Duchenne and Becker muscular dystrophies, collectively referred to as dystrophinopathies, are recessive X-linked disorders characterized by progressive muscle weakness and ultimately cardiac and respiratory failure. Immediate family members are often primary caregivers of individuals with a dystrophinopathy.

Methods

We explored the impact of this role by inviting primary caregivers (n = 209) of males diagnosed with childhood-onset dystrophinopathy who were identified by the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) to complete a mailed questionnaire measuring perceived social support and stress, spirituality, and family quality of life (FQoL). Bivariate and multivariate analyses examined associations between study variables using the Double ABCX model as an analytic framework.

Results

Higher stressor pile-up was associated with lower perceived social support (r = -0.29, p < .001), availability of supportive family (r = -0.30, p < .001) or non-family (r = -0.19, p < .01) relationships, and higher perceived stress (r = 0.33, p < .001); but not with spirituality (r = -0.14, p > 0.05). FQoL was positively associated with all support measures (correlations ranged from: 0.25 to 0.58, p-values 0.01–0.001) and negatively associated with perceived stress and control (r = -0.49, p < .001). The association between stressor pile-up and FQoL was completely mediated through global perceived social support, supportive family relationships, and perceived stress and control; supportive non-family relationships did not remain statistically significant after controlling for other mediators.

Conclusions

Findings suggest caregiver adaptation to a dystrophinopathy diagnosis can be optimized by increased perceived control, supporting family resources, and creation of a healthy family identity. Our findings will help identify areas for family intervention and guide clinicians in identifying resources that minimize stress and maximize family adaptation.

Noninvasive ventilation for neuromuscular respiratory failure: when to use and when to avoid

PURPOSE OF REVIEW

Neuromuscular respiratory failure can occur from a variety of diseases, both acute and chronic with acute exacerbation. There is often a misunderstanding about how the nature of the neuromuscular disease should affect the decision on how to ventilate the patient. This review provides an update on the value and relative contraindications for the use of noninvasive ventilation in patients with various causes of primary neuromuscular respiratory failure.

RECENT FINDINGS

Myasthenic crisis represents the paradigmatic example of the neuromuscular condition that can be best treated with noninvasive ventilation. Timely use of noninvasive ventilation can substantially reduce the duration of ventilatory assistance in these patients. Noninvasive ventilation can also be very helpful after extubation in patients recovering from an acute cause of neuromuscular respiratory failure who have persistent weakness. Noninvasive ventilation can improve quality of survival in patients with advanced motor neuron disorder (such as amyotrophic lateral sclerosis) and muscular dystrophies, and can avoid intubation when these patients present to the hospital with acute respiratory failure. Attempting noninvasive ventilation is not only typically unsuccessful in patients with Guillain-Barre syndrome, but can also be dangerous in these cases.

SUMMARY

Noninvasive ventilation can be very effective to treat acute respiratory failure caused by myasthenia gravis and to prevent reintubation in other neuromuscular patients, but should be used cautiously for other indications, particularly Guillain-Barre syndrome.

Current and emerging treatment strategies for Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy in childhood. It is caused by mutations of the DMD gene, leading to progressive muscle weakness, loss of independent ambulation by early teens, and premature death due to cardiorespiratory complications. The diagnosis can usually be made after careful review of the history and examination of affected boys presenting with developmental delay, proximal weakness, and elevated serum creatine kinase, plus confirmation by muscle biopsy or genetic testing. Precise characterization of the DMD mutation is important for genetic counseling and individualized treatment. Current standard of care includes the use of corticosteroids to prolong ambulation and to delay the onset of secondary complications. Early use of cardioprotective agents, noninvasive positive pressure ventilation, and other supportive strategies has improved the life expectancy and health-related quality of life for many young adults with DMD. New emerging treatment includes viral-mediated microdystrophin gene replacement, exon skipping to restore the reading frame, and nonsense suppression therapy to allow translation and production of a modified dystrophin protein. Other potential therapeutic targets involve upregulation of compensatory proteins, reduction of the inflammatory cascade, and enhancement of muscle regeneration. So far, data from DMD clinical trials have shown limited success in delaying disease progression; unforeseen obstacles included immune response against the generated mini-dystrophin, inconsistent evidence of dystrophin production in muscle biopsies, and failure to demonstrate a significant improvement in the primary outcome measure, as defined by the 6-minute walk test in some studies. The long-term safety and efficacy of emerging treatments will depend on the selection of appropriate clinical end points and sensitive biomarkers to detect meaningful changes in disease progression. Correction of the underlying mutations using new gene-editing technologies and corticosteroid analogs with better safety profiles offers renewed hope for many individuals with DMD and their families.

Impact of invasive ventilation on survival when non-invasive ventilation is ineffective in patients with Duchenne muscular dystrophy: A prospective cohort

BACKGROUND

Many patients with DMD undergo tracheostomy. Tracheostomy is associated with certain complications, however its effect on prognosis is not known.

METHODS

The relationship between type of mechanical ventilation and survival at 12 years was evaluated in a prospective cohort of patients with Duchenne muscular dystrophy followed in a French reference center for Neuromuscular Diseases. Cox proportional-hazards regressions were used to estimate the hazard ratios associated with risk of switching from non-invasive to invasive ventilation, and with risk of death.

RESULTS

One hundred and fifty patients were included. Initial use of invasive ventilation was associated with an episode of acute respiratory failure (p < 0.0001) and with a severe clinical status (p < 0.05). Risk of death was associated with swallowing disorders (2.51, IC [1.12-5.66], p < 0.03) and cardiac failure (p < 0.05) but not with type of mechanical ventilation.

CONCLUSION

Switching to invasive ventilation is appropriate when non-invasive ventilation is ineffective.

Pediatric Pulmonology year in review 2014: Part 1

Our discipline and our journal cover an extremely broad range of research and scholarly topics related to children's respiratory disorders. To better meet the needs of our readership for updated perspectives on the rapidly expanding knowledge in our field, we here summarize the past year's publications in our major topic areas, as well as selected publications in these areas from the core clinical journal literature outside our own pages.

Open circuit mouthpiece ventilation: Concise clinical review

In 2013 new "mouthpiece ventilation" modes are being introduced to commercially available portable ventilators. Despite this, there is little knowledge of how to use noninvasive intermittent positive pressure ventilation (NIV) as opposed to bi-level positive airway pressure (PAP) and both have almost exclusively been reported to have been used via nasal or oro-nasal interfaces rather than via a simple mouthpiece. Non-invasive ventilation is often reported as failing because of airway secretion encumbrance, because of hypercapnia due to inadequate bi-level PAP settings, or poor interface tolerance. The latter can be caused by factors such as excessive pressure on the face from poor fit, excessive oral air leak, anxiety, claustrophobia, and patient-ventilator dys-synchrony. Thus, the interface plays a crucial role in tolerance and effectiveness. Interfaces that cover the nose and/or nose and mouth (oro-nasal) are the most commonly used but are more likely to cause skin breakdown and claustrophobia. Most associated drawbacks can be avoided by using mouthpiece NIV. Open-circuit mouthpiece NIV is being used by large populations in some centers for daytime ventilatory support and complements nocturnal NIV via "mask" interfaces for nocturnal ventilatory support. Mouthpiece NIV is also being used for sleep with the mouthpiece fixed in place by a lip-covering flange. Small 15 and 22mm angled mouthpieces and straw-type mouthpieces are the most commonly used. NIV via mouthpiece is being used as an effective alternative to ventilatory support via tracheostomy tube (TMV) and is associated with a reduced risk of pneumonias and other respiratory complications. Its use facilitates "air-stacking" to improve cough, speech, and pulmonary compliance, all of which better maintain quality of life for patients with neuromuscular diseases (NMDs) than the invasive alternatives. Considering these benefits and the new availability of mouthpiece ventilator modes, wider knowledge of this technique is now warranted. This review highlights the indications, techniques, advantages and disadvantages of mouthpiece NIV.