Mechanisms of improvement of respiratory failure in patients with restrictive thoracic disease treated with non-invasive ventilation

Perioperative Management in Neuromuscular Diseases: A Narrative Review

Patients with neuromuscular diseases are particularly vulnerable in the perioperative period to the development of pulmonary and cardiac complications, or medication side effects. These risks could include hypoventilation, aspiration pneumonia, exacerbation of underlying cardiomyopathy, arrhythmias, adrenal insufficiency, prolonged neuromuscular blockade, issues related to thermoregulation, rhabdomyolysis, malignant hyperthermia, or prolonged mechanical ventilation. Interventions at each of the perioperative stages can be implemented to mitigate these risks. A careful pre-operative evaluation may help identify risk factors so that appropriate interventions are initiated, including cardiology consultation, pulmonary function tests, initiation of noninvasive ventilation, or implementation of preventive measures. Important intraoperative issues include positioning, airway and anesthetic management, and adequate ventilation. The postoperative period may require correction of electrolyte abnormalities, control of secretions with medications, manual or mechanical cough assistance, avoiding the risk of reintubation, judicious pain control, and appropriate medication management. The aim of this review is to increase awareness of the particular surgical challenges in this vulnerable population, and guide the clinician on the various evaluations and interventions that may result in a favorable surgical outcome.

A history of home mechanical ventilation: The past, present and future

This state-of-the-art review provides an overview of the history of home mechanical ventilation (HMV), including early descriptions of mechanical ventilation from ancient and Renaissance perspectives and the mass development of ventilators designed for long-term use during the poliomyelitis epidemic. Seminal data from key clinical trials supports the application of HMV in certain patients with chronic obstructive pulmonary disease, neuromuscular disease and obesity-related respiratory failure. Innovative engineering coupled with refined physiological understanding now permits widespread delivery of home mechanical ventilation to a global population, using portable devices with advanced ventilatory modes and telemonitoring capabilities. Exponential growth in digital technology continues, and ongoing research is needed to understand how to harness clinical and physiological data to benefit patients and healthcare services in a clinically- and cost-effective manner.

International Survey of the Tools Used for Assessment, Monitoring and Management of Home Mechanical Ventilation Patients

BACKGROUND

There are limited data reporting diagnostic practices, compared to clinical guidelines, for patients with chronic respiratory failure requiring home mechanical ventilation (HMV). There are no data detailing the current use of downloaded physiological monitoring data in day-to-day clinical practice during initiation and follow up of patients on HMV. This survey reports clinicians' practices, with a specific focus on the clinical approaches employed to assess, monitor and manage HMV patients.

METHODS

A web-based international survey was open between 1 January and 31 March 2023.

RESULTS

In total, 114 clinicians responded; 84% of the clinicians downloaded the internal physiological ventilator data when initiating and maintaining HMV patients, and 99% of the clinicians followed up with patients within 3 months. Adherence, leak and the apnea-hypopnea index were the three highest rated items. Oxygen saturation was used to support a diagnosis of nocturnal hypoventilation and was preferred over measurements of carbon dioxide. Furthermore, 78% of the clinicians reviewed data for the assessment of patient ventilator asynchrony (PVA), although the confidence reported in identifying certain PVAs was reported as unconfident or extremely unconfident.

CONCLUSIONS

This survey confirmed that clinical practice varies and often does not follow the current guidelines. Despite PVA being of clinical interest, its clinical relevance was not clear, and further research, education and training are required to improve clinical confidence.

Pulmonary and clinical outcomes of patients with severe rigid scoliosis and type I respiratory failure treated with halo-pelvic distraction

BACKGROUND

The severe rigid scoliosis patients with type I respiratory failure could not tolerate complicated corrective surgery. Preoperative halo-pelvic distraction (HPD) is used to reduce the curve magnitude and improve the pulmonary function before surgery. The present study aimed to retrospectively analyze the pulmonary and clinical outcomes of preoperative HPD in severe rigid spinal deformity with type I respiratory failure.

METHODS

Eighteen cases of severe rigid scoliosis and type I respiratory failure treated with preoperative HPD and corrective surgery for spinal deformity between 2016 and 2018 were retrospectively reviewed. Patient demographics, major coronal curve and kyphosis, correction rates, heights, pulmonary function, distraction time, and postoperative neurological complications were recorded for all cases.

RESULTS

The averaged duration of distraction was 9.1 ± 2.3 months. The coronal curve was corrected from 168° ± 14° to 58° ± 11° at the end of HPD. The kyphosis curve reduced from 151° ± 29° to 65° ± 10°. Meanwhile, the mean stand body height increased by 23.9 ± 5.3 cm. Significantly increased mean FVC (1.52 ± 0.43 L vs. 0.95 ± 0.44 L) and improved percent-predicted values for FVC (37 ± 10% vs. 23 ± 9%) were observed after HPD. The pressure of oxygen (PaO2) increased from 54.5 ± 2.0 to 84.8 ± 4.7 mmHg. Scoliosis and kyphosis curve, respectively, averaged 48 ± 8°and 30 ± 14° after final fusion and instrumentation, with a mean correction of 71% and 80%, respectively. No severe complication occurred during the distraction.

CONCLUSIONS

HPD may be useful for severe rigid scoliosis patients with type I respiratory failure. Pulmonary functions in patients with severe rigid scoliosis can be significantly improved by HPD. They are then better able to tolerate complicated corrective surgery.

Home Noninvasive Ventilation for COPD

Patients with hypercapnic COPD appear to represent a phenotype driven by specific physiology including air trapping and mechanical disadvantage, sleep hypoventilation, and sleep apnea. Such individuals appear to be at high risk for adverse health outcomes. Home noninvasive ventilation (NIV) has been shown to have the potential to help compensate for physiological issues underlying hypercapnia. In contrast to older literature, contemporary clinical trials of home NIV have been shown to improve patient-oriented outcomes including quality of life, hospitalizations, and mortality. Advancements in the use of NIV, including the use of higher inspiratory pressures, may account for recent success. Successful practical application of home NIV thus requires an adequate understanding of patient selection, devices and modes, and strategies for titration. The emergence of telemonitoring holds promise for further improvements in patient care by facilitating titration, promoting adherence, troubleshooting issues, and possibly predicting exacerbations. Given the complexity of home NIV, clinicians and health systems might consider establishment of dedicated home ventilation programs to provide such care. In addition, incorporation of respiratory therapist expertise is likely to improve success. Traditional fee-for-service structures have been a challenge for financing such programs, but ongoing changes toward value-based care are likely to make home NIV programs more feasible.

Effect of Intensity of Home Noninvasive Ventilation in Individuals With Neuromuscular and Chest Wall Disorders: A Systematic Review and Meta-Analysis of Individual Participant Data

INTRODUCTION

Home noninvasive ventilation (NIV), targeting a reduction of carbon dioxide with a combination of sufficient inspiratory support and backup-rate improves outcomes in patients with chronic obstructive pulmonary disease. The aim of this systematic review with individual participant data (IPD) meta-analysis was to evaluate the effects of intensity of home NIV on respiratory outcomes in individuals with slowly progressive neuromuscular (NMD) or chest-wall disorders (CWD).

METHODS

Controlled, non-controlled and cohort studies indexed between January-2000 and December-2020 were sought from Medline, Embase and the Cochrane Central Register. Outcomes were diurnal PaCO₂, PaO₂, daily NIV usage, and interface type (PROSPERO-CRD 42021245121). NIV intensity was defined according to the Z-score of the product of pressure support (or tidal volume) and backup-rate.

RESULTS

16 eligible studies were identified; we obtained IPD for 7 studies (176 participants: 113-NMD; 63-CWD). The reduction in PaCO₂ was greater with higher baseline PaCO₂. NIV intensity per se was not associated with improved PaCO₂ except in individuals with CWD and the most severe baseline hypercapnia. Similar results were found for PaO₂. Daily NIV usage was associated with improvement in gas exchange but not with NIV intensity. No association between NIV intensity and interface type was found.

CONCLUSION

Following home NIV initiation in NMD or CWD patients, no relationship was observed between NIV intensity and PaCO₂, except in individuals with the most severe CWD. The amount of daily NIV usage, rather than intensity, is key to improving hypoventilation in this population during the first few months after introduction of therapy.

Respiratory prehabilitation in pediatric anesthesia in children with muscular and neurologic disease

Children with neuromuscular, chronic neurologic, and chest wall diseases are at increased risk of postoperative respiratory complications including atelectasis, pneumonia, and respiratory failure with the possible need for reintubation or even tracheostomy. These complications negatively impact patient outcomes, including increased healthcare resource utilization and increased surgical mortality. In these children, the existing respiratory reserve is often inadequate to withstand the stresses brought on during anesthesia and surgery. A thorough clinical assessment and objective evaluation of pulmonary function and gas exchange can help identify which children are at particular risk for poor postoperative outcomes and thus merit preoperative interventions. These may include initiation and optimization of non-invasive ventilation and mechanical insufflation-exsufflation. Furthermore, such an evaluation will help identify children who may require a postoperative extubation plan tailored to neuromuscular diseases. Such strategies may include avoidance of pre-extubation lung decruitment by precluding continuous positive airway pressure trials, aggressively weaning to room air and directly extubating to non-invasive ventilation with a high inspiratory to expiratory pressure differential of at least 10 cm H20. Children with cerebral palsy and other neurodegenerative or neurodevelopmental disorders are a more heterogeneous group of children who may share some operative risk factors with children with neuromuscular disease; they may also be at risk of sleep-disordered breathing, may also require non-invasive ventilation or mechanical insufflation-exsufflation, and may have associated chronic lung disease from aspirations that may require perioperative treatment.

Long-Term Effect of Noninvasive Ventilation on Diaphragm in Chronic Respiratory Failure

Purpose

Home non-invasive ventilation (NIV) is recommended in patients with COPD and hypercapnic chronic respiratory failure (HCRF). The mechanism by it can improve alveolar ventilation during spontaneous breathing is not yet completely explained. Our aim is to evaluate the impact of on diaphragm muscle function in a series of patients with HCRF.

Patients and Methods

Observational, longitudinal, prospective study of a series of patients with very severe chronic obstruction to airflow treated with home high imntensity NIV (HINIV). Patients underwent a baseline and after 12 months assessment including adherence to treatment, quality of life, respiratory function tests and diaphragmatic ultrasound. SPSS v.26 software was used for statistical analysis.

Results

We studied 30 patients, 63% male, the mean age was 60.8 (±6.4) years old. Patients had a severe obstructive ventilatory pattern [FEV1 21.8 (±6.1)%] and hypercapnia [pCO2 56.4 (±7.2) mmHg]. After 12 months of HINIV, we observed significant increases in FVC of 9.2% (p = 0.002), FEV1 of 3.5% (p = 0.04), MIP of 9.4% (p = 0.006), and 6-minute-walking test (6MWT) of 31.9 m (p = 0.001), as well as decreases in paCO2 of 12.5 mmHg (p = 0.001), HCO3 of 4.7 mmol/L (p = 0.001) and BODE index from 7 to 6. Diaphragmatic ultrasound demonstrated an increase in the thickening fraction of 14% (p = 0.002). Respiratory symptoms (p = 0.04), physical function (p = 0.03), and sleep (p = 0.04) also improved.

Conclusion

In patients with HCRF due to very severe chronic obstruction to airflow, long-term HINIV can improve respiratory performance by improving the function of the diaphragmatic musculature. Larger multicenter clinical trials are needed to confirm the results suggested in this study.

Measuring Adherence to Long-Term Noninvasive Ventilation

BACKGROUND

Obtaining benefits from long-term noninvasive ventilation (NIV) relies on achieving adequate adherence to treatment. Reported adherence to NIV is variable and could be influenced by high-volume users and attrition of nonusers and those who die. This observational study aimed to describe patterns of use and adherence rates in new unselected users of NIV.

METHODS

All adults (> 18 y old) commencing long-term NIV were consecutively enrolled and followed for 6 months. Ventilator data were manually downloaded from devices and usage (minutes per day) was collected. Subjects were categorized into adherent users (≥ 4 h/d) and nonadherent users (< 4 h/d).

RESULTS

Data were obtained from 86 subjects. Most (65%) had motor neuron disease, and most commenced NIV in an out-patient setting (72%). At one month after NIV implementation, overall average daily use was 302.1 min/d and categorical adherence was 57%. At 6 months or prior to death, overall average daily use increased (388.7 min/d), but categorical adherence was similar (62%). The majority of subjects (84%) remained in the same adherence category from their first month to their sixth month of use or death. Individuals with motor neuron disease demonstrated significantly lower rates of adherence compared to the rest of the cohort at 1 month (48% vs 73%, P = .03). In those who died within the study period (n = 19, all with motor neuron disease), this difference persisted to death (42% at death vs 73% at 6 months, P = .032).

CONCLUSIONS

Average daily usage may conceal true prevalence of adherence or nonadherence to NIV within a population. Reporting both average daily use data and categorical adherence rates (using a threshold of 4 h/d) may improve transparency of reported outcomes from clinical trials and identifies a therapeutic target for home mechanical ventilation services for quality improvement.

Noninvasive Home Mechanical Ventilation in Adult Myotonic Dystrophy Type 1: A Systematic Review

INTRODUCTION

Chronic hypercapnic respiratory failure induces considerable morbidity and mortality in patients with myotonic dystrophy type 1 (DM1). This study systematically reviews the effects of noninvasive home mechanical ventilation (HMV) on gas exchange, quality of life, survival, and compliance in DM1 patients.

METHODS

A systematic Medline and Embase search was performed (January 1995 to January 2020). Records were screened for eligibility criteria, data were extracted from included studies, and risk of bias was assessed. We present findings mainly using a narrative synthesis.

RESULTS

Twenty-eight relevant full-text articles were screened for eligibility criteria. Nine studies were included. Randomized controlled trials were not found. Studies had either an observational (n = 8) or interventional (n = 1) design. In the pooled data analysis, HMV showed to improve mean oxygen saturation with 4.8% and decreased mean carbon dioxide values with 3 mm Hg. Compliance varied widely between studies, from no use to more than 12 h per day. Quality of life was not studied extensively, but some studies reported positive effects of HMV on symptoms of chronic respiratory failure. HMV may improve survival in DM1 patients with chronic hypercapnic respiratory failure.

CONCLUSION

This review shows that HMV can improve gas exchange and relieve symptoms with a possible survival benefit in DM1 patients with chronic hypercapnic respiratory failure. Future studies should focus on developing strategies to optimize the timing of HMV initiation and to promote compliance.

The effect of emerging molecular and genetic therapies on cardiopulmonary disease in Duchenne muscular dystrophy

Gene therapy is an attractive approach being intensively studied to prevent muscle deterioration in patients with Duchenne muscular dystrophy. While clinical trials are only in early stages, initial reports are promising for its effects on ambulation. Cardiopulmonary failure, however, is the most common cause of mortality in Duchenne muscular dystrophy (DMD) patients, and little is known regarding the prospects for gene therapy on alleviating DMD-associated cardiomyopathy and respiratory failure. Here we review current knowledge regarding effects of gene therapy on DMD cardiomyopathy and discuss respiratory endpoints that should be considered as outcome measures in future clinical trials.

Titration and follow-up for home noninvasive positive pressure ventilation in chronic obstructive pulmonary disease: The potential role of tele-monitoring and the Internet of things

INTRODUCTION

Home noninvasive positive pressure ventilation (NIPPV) has become a well-established treatment for stable hypercapnic chronic obstructive pulmonary disease (COPD) patients. There are still other challenges including appropriate titration of ventilator parameters, adequacy of follow-up, monitoring, and management at home to ensure effectiveness and security, and to improve quality of life. The Internet of Things (IoT) is the name given to the network of devices and other "things" with built-in sensors, software, electronics, and network connectivity, which can communicate these objects over wireless networks and then send data to a cloud platform. Reliable tele-monitoring and transmission of clinical parameters from home to hospitals have prompted the development of IoT-based home NIPPV.

OBJECTIVES

This review provides an overview of titration and follow-up of home NIPPV and focuses on different technologies, modalities, managements, and cost-effectiveness used in IoT-based tele-monitoring of home mechanical ventilation.

DATA SOURCE

Literature search of Web of Science, PubMed, and EMBASE was made to find relevant articles about tele-monitoring and the IoT in home mechanical ventilation over the last 15 years. We used the following search terms: NIPPV, COPD, home mechanical ventilation, telemedicine, tele-monitoring, and management.

CONCLUSION

IoT-based management of home NIPPV, such as home titration and follow-up with the use of tele-monitoring, are emerging and yielding positive findings. However, clear conclusions based on RCT of tele-monitoring in COPD patients with NIPPV at home are only a few and large-scale multicenter studies are required for replication and further validation.

Typical within and between person variability in non-invasive ventilator derived variables among clinically stable, long-term users

Background

Despite increasing capacity to remotely monitor non-invasive ventilation (NIV), how remote data varies from day to day and person to person is poorly described.

Methods

Single-centre, 2-month, prospective study of clinically stable adults on long-term NIV which aimed to document NIV-device variability. Participants were switched to a ventilator with tele-monitoring capabilities. Ventilation settings and masking were not altered. Raw, extensible markup language data files were provided directly from Philips Respironics (EncoreAnywhere). A nested analysis of variance was conducted on each ventilator variable to apportion the relative variation between and within participants.

Results

Twenty-nine people were recruited (four withdrew, one had insufficient data for analyses; 1364 days of data). Mean age was 54.0 years (SD 18.4), 58.3% male with body mass index of 37.0 kg/m² (13.7). Mean adherence was 8.53 (2.23) hours/day and all participants had adherence >4 hours/day. Variance in ventilator-derived indices was predominantly driven by differences between participants; usage (61% between vs 39% within), Apnoea–Hypopnoea Index (71% vs 29%), unintentional (64% vs 36%) and total leak (83% vs 17%), tidal volume (93% vs 7%), minute ventilation (92% vs 8%), respiratory rate (92% vs 8%) and percentage of triggered breaths (93% vs 7%).

Interpretation

In this clinically stable cohort, all device-derived indices were more varied between users than the day-to-day variation within individuals. We speculate that normative ranges and thresholds for clinical intervention need to be individualised, and further research is necessary to determine the clinically important relationships between clinician targets for therapy and patient-reported outcomes.

Management of Chronic Respiratory Failure in Chronic Obstructive Pulmonary Disease: High-Intensity and Low-Intensity Ventilation

A significant body of literature supports the benefit of noninvasive ventilation (NIV) for acute hypercapnia in the setting of exacerbations of chronic obstructive pulmonary disease (COPD). In those with severe COPD with chronic hypercapnic respiratory failure, however, the role of NIV has been more controversial. This article reviews the physiologic basis for considering NIV in patients with COPD, summarizes existing evidence supporting the role of NIV in COPD, highlights the patient population and ventilatory approach most likely to offer benefit, and suggests a potential clinical pathway for managing patients.

Long-Term Mechanical Ventilation: Recommendations of the Swiss Society of Pulmonology

Long-term mechanical ventilation is a well-established treatment for chronic hypercapnic respiratory failure (CHRF). It is aimed at improving CHRF-related symptoms, health-related quality of life, survival, and decreasing hospital admissions. In Switzerland, long-term mechanical ventilation has been increasingly used since the 1980s in hospital and home care settings. Over the years, its application has considerably expanded with accumulating evidence of beneficial effects in a broad range of conditions associated with CHRF. Most frequent indications for long-term mechanical ventilation are chronic obstructive pulmonary disease, obesity hypoventilation syndrome, neuromuscular and chest wall diseases. In the current consensus document, the Special Interest Group of the Swiss Society of Pulmonology reviews the most recent scientific literature on long-term mechanical ventilation and provides recommendations adapted to the particular setting of the Swiss healthcare system with a focus on the practice of non-invasive and invasive home ventilation in adults.

[Variation in ventilatory response to CO2 in patients treated by non-invasive ventilation]

INTRODUCTION

There are many mechanisms for improving the clinical and blood gas status of patients with the obesity hypoventilation syndrome (OHS) or chronic obstructive pulmonary disease (COPD) by non-invasive ventilation (NIV) at home. Our objective was to set up a pilot study to evaluate the potential modification of the sensitivity of the respiratory centers to CO₂ by NIV in paired new COPD and OHS patients.

METHODS

We assessed the sensitivity of the respiratory centers to CO₂ by the Read method in 3 COPD patients and 3 OHS patients newly treated by NIV and again 3 months later. We compared their results to those of 6 control subjects.

RESULTS

All the patients included had altered ventilatory responses to CO₂ with slopes of less of than 1 L.min^-1.mmHg^-1. Mean coefficients of variation were significantly higher in patients than in healthy subjects (P=0.007). Patients who improved their CO₂ sensitivity slope were those most observant of NIV.

CONCLUSION

This work showed significant changes in the ventilatory response to hypercapnia in patients with either OHS or COPD after NIV therapy. The significance of these changes deserves to be studied.

Noninvasive volume-assured pressure support for chronic respiratory failure: a review

PURPOSE OF REVIEW

Noninvasive ventilation (NIV) is an established treatment for chronic hypercapnic respiratory failure (CRF). Volume-assured pressure support (VAPS) is a mode of NIV that automatically adjusts inspiratory pressure in order to maintain a constant respiratory volume. We aim to discuss the role and application of VAPS in CRF.

RECENT FINDINGS

Recently published meta-analyses and reviews fail to demonstrate a significant difference in gas exchange, sleep, or quality-of-life improvement between VAPS and bilevel positive airway pressure (BPAP) in patients with CRF. A recent manuscript suggests that VAPS therapy in chronic obstructive pulmonary disease patients may reduce the number of exacerbations. It has been shown that with a protocol-driven approach BPAP and VAPS can both be successfully titrated during a single split-night polysomnography.

SUMMARY

VAPS is as effective as other modes of NIV at improving ventilation and sleep in CRF. The potential advantage is a more consistent ventilatory support through daytime-nighttime variations and progression of disease over time. However, the impact on long-term outcomes, such as survival, has not been studied.

Dose-response characteristics of noninvasive ventilation in acute respiratory failure

Acute noninvasive ventilation (NIV) is a well-established therapy for acute respiratory failure but the dose–response characteristics of this therapy have not been defined. The aim of this study was to define this dose–response relationship.

This study was a retrospective review of patients receiving NIV for acute respiratory failure in a tertiary hospital respiratory high-dependency unit between July 2012 and June 2017. Mask-on time (rather than the period that NIV was in use) as the “dose” was compared with hospital survival as the “response”.

654 patients were included, 594 (91%) with hypercapnic respiratory failure (HCRF). NIV was used for a median (interquartile range (IQR)) duration of 2.74 (1.51–4.73) days and median (IQR) mask-on time was 34 (18–60) h (56.1% (41.2–69.5%) of treatment time). There was evidence of a dose–response relationship in the HCRF group up to a ceiling of 24 h mask-on time, but not in the hypoxaemic respiratory failure (HRF) group. There was a difference in survival with as little as 2 h mask-on time (92% compared with 73%; p<0.001). Patients requiring NIV for 80–100% of therapy time had lower survival.

We conclude that there is evidence of a dose–response relationship between cumulative NIV usage (mask-on time) and survival from as little as 2 h to a ceiling of ∼24 h in HCRF, but not in HRF.

Acute NIV in respiratory failure has a dose–response effect on survival from as little as 2 h of therapyhttp://bit.ly/2okErQZ

Respiratory Involvement in Patients with Neuromuscular Diseases: A Narrative Review

Respiratory muscle weakness is a major cause of morbidity and mortality in patients with neuromuscular diseases (NMDs). Respiratory involvement in NMDs can manifest broadly, ranging from milder insufficiency that may affect only sleep initially to severe insufficiency that can be life threatening. Patients with neuromuscular diseases exhibit very often sleep-disordered breathing, which is frequently overlooked until symptoms become more severe leading to irreversible respiratory failure necessitating noninvasive ventilation (NIV) or even tracheostomy. Close monitoring of respiratory function and sleep evaluation is currently the standard of care. Early recognition of sleep disturbances and initiation of NIV can improve the quality of life and prolong survival. This review discusses the respiratory impairment during sleep in patients with NMDs, the diagnostic tools available for early recognition of sleep-disordered breathing and the therapeutic options available for overall respiratory management of patients with NMDs.

Non-invasive ventilation in palliative care: a systematic review

INTRODUCTION

An ageing population and steady increase in the rates of neoplasms and chronic degenerative diseases poses a challenge for societies and their healthcare systems. Because of the recent and continued advances in therapies, such as the development and widespread use of non-invasive ventilation (NIV), survival rates have increased for these pathologies. For patients with end-stage chronic respiratory diseases, the use of NIV following the onset of acute or severe chronic respiratory failure is a valid option when intubation has been excluded.

EVIDENCE ACQUISITION

The following electronic databases were searched from their inception to January 2000 to December 2017: MEDLINE, EMBASE, CINHAIL, CENTRAL (Cochrane Central register of Controlled Trials), DARE (Database of Abstracts of Reviews of Effectiveness), the Cochrane Database of Systematic Reviews, ACP Journal Club database.

EVIDENCE SYNTHESIS

The available evidence strongly supports the use of NIV in patients presenting with an exacerbation of chronic obstructive pulmonary disease, as well end-stage neuromuscular disease. Few studies support the use of NIV in end-stage interstitial lung disease and in morbid obesity patients. In patients with cancer has been recommend offering NIV as palliative care to improve dyspnea.

CONCLUSIONS

The decision regarding the treatment should be made by the patient, ideally before reaching the terminal stage and after having a frank dialogue with healthcare professionals and family members.

Randomised controlled trial of polysomnographic titration of noninvasive ventilation

Noninvasive ventilation (NIV) settings determined during wakefulness may produce patient–ventilator asynchrony (PVA) during sleep, causing sleep disruption and limiting tolerance. This study investigated whether NIV titrated with polysomnography (PSG) is associated with less PVA and sleep disruption than therapy titrated during daytime alone.

Treatment-naive individuals referred for NIV were randomised to control (daytime titration followed by sham polysomnographic titration) or PSG (daytime titration followed by polysomnographic titration) groups. Primary outcomes were PVA and arousal indices on PSG at 10 weeks. Secondary outcomes included adherence, gas exchange, symptoms and health-related quality of life (HRQoL).

In total, 60 participants were randomised. Most (88.3%) had a neuromuscular disorder and respiratory muscle weakness but minor derangements in daytime arterial blood gases. PVA events were less frequent in those undergoing polysomnographic titration (median (interquartile range (IQR)): PSG 25.7 (12–68) events·h−1versuscontrol 41.0 (28–182) events·h−1; p=0.046), but arousals were not significantly different (median (IQR): PSG 11.4 (9–19) arousals·h−1versuscontrol 14.6 (11–19) arousals·h−1; p=0.258). Overall adherence was not different except in those with poor early adherence (<4 h·day−1) who increased their use after polysomnographic titration (mean difference: PSG 95 (95% CI 29–161) min·day−1versuscontrol −23 (95% CI −86–39) min·day−1; p=0.01). Arterial carbon dioxide tension, somnolence and sleep quality improved in both groups. There were no differences in nocturnal gas exchange or overall measures of HRQoL.

NIV titrated with PSG is associated with less PVA but not less sleep disruption when compared with therapy titrated during daytime alone.

The Pathophysiology of Respiratory Failure: Control of Breathing, Respiratory Load, and Muscle Capacity

The purpose of this review is to provide an overview on how interactions between control of breathing, respiratory load, and muscle function may lead to respiratory failure. The mechanisms involved vary according to the underlying pathology, but respiratory failure is most often the result of an imbalance between the muscular pump and the mechanical load placed upon it. Changes in respiratory drive and response to CO2 seem to be important contributors to the pathophysiology of respiratory failure. Inspiratory muscle dysfunction is also frequent but is not a mandatory prerequisite to respiratory failure since increased load may also be sufficient to precipitate it. It is crucial to recognize these interactions to be able to timeously establish patients on mechanical ventilation and adapt the ventilator settings to their respiratory system physiology.

The role of sleep diagnostics and non-invasive ventilation in children with spinal muscular atrophy

Spinal muscular atrophy (SMA) is a degenerative motor neurone disorder causing progressive muscular weakness. Without assisted ventilation or novel therapies, most children with SMA type 1 die before the second year of life due to respiratory failure as the respiratory muscles and bulbar function are severely affected. Active respiratory treatment (mechanically assisted cough, invasive or non-invasive ventilation) has improved survival significantly in recent decades, but often at the cost of becoming ventilator dependent. The advent of a new oligonucleotide based therapy (Nusinersen) has created new optimism for improving motor function. However, the long-term effect on respiratory function is unclear and non-invasive respiratory support will remain an important part of medical management in patients with SMA. This review summarises the existing knowledge about sleep-disordered breathing and respiratory failure in patients with SMA, especially type 1, as well as the evidence of improved outcome and survival in patients treated with non-invasive or invasive ventilation. Practical considerations and ethical concerns are delineated with discussion on how these may be affected by the advent of new therapies such as Nusinersen.

Correction of Paradoxical Ribcage Motion in Scoliosis by Noninvasive Ventilation

STUDY DESIGN

Observational study of ribcage motion in scoliosis.

OBJECTIVE

To see whether noninvasive ventilation corrected paradoxical inward motion of the ribs during inspiration.

SUMMARY OF BACKGROUND DATA

Paradoxical inward motion of the ribs is observed after rib fractures, low cervical cord injury, and in chronic obstructive pulmonary disease. It is not well recognized in scoliosis and the mechanism in this group has not been studied.

METHODS

Linearized magnetometers were used to measure the diameter of the ribcage. Changes in diameter during tidal breathing were recorded during spontaneous ventilation and noninvasive ventilation in 10 subjects with idiopathic or congenital thoracic scoliosis.

RESULTS

During spontaneous breathing, the median change in ribcage diameter during inspiration was -1.5 (range -2.3 to -0.8) cm. The median change in ribcage diameter during noninvasive ventilation was +0.5 (range -1.1 to +1.2) cm. Noninvasive ventilation improved paradoxical motion in all subjects, completely correcting it in six.

CONCLUSION

Paradoxical inward motion of the ribcage is seen in some subjects with severe scoliosis. This abnormal motion is improved or abolished by noninvasive ventilation. Since noninvasive ventilation takes over the work of breathing from the respiratory muscles, we suggest that inspiratory muscle contraction causes distortion of part of the ribcage in scoliosis, probably because of the abnormal orientation of diaphragmatic muscle fibers.

LEVEL OF EVIDENCE

2.

Positive airway pressure devices for the management of breathlessness

PURPOSE OF REVIEW

Breathlessness is a common symptom in many chronic diseases and may be refractory to pharmacotherapy. In this review, we discuss the pathophysiology of breathlessness and the role of positive airway pressure (PAP) devices to ameliorate it.

RECENT FINDINGS

Breathlessness is directly related to neural respiratory drive, which can be modified by addressing the imbalance between respiratory muscle load and capacity. Noninvasive PAP devices have been applied to patients limited by exertional breathless and, as the disease progresses, breathlessness at rest. The application of PAP is focussed on addressing the imbalance in load and capacity, aiming to reduce neural respiratory drive and breathlessness. Indeed, noninvasive bi-level PAP devices have been employed to enhance exercise capacity by enhancing pulmonary mechanics and reduce neural drive in chronic obstructive pulmonary disease (COPD) patients, and reduce breathlessness for patients with progressive neuromuscular disease (NMD) by enhancing respiratory muscle capacity. Novel continuous PAP devices have been used to maintain central airways patency in patients with excessive dynamic airway collapse (EDAC) and target expiratory flow limitation in severe COPD.

SUMMARY

PAP devices can reduce exertional and resting breathlessness by reducing the load on the system and enhancing capacity to reduce neural respiratory drive.

[Non-invasive and invasive out of hospital ventilation in chronic respiratory failure : Consensus report of the working group on ventilation and intensive care medicine of the Austrian Society of Pneumology]

The current consensus report was compiled under the patronage of the Austrian Society of Pneumology (Österreichischen Gesellschaft für Pneumologie, ÖGP) with the intention of providing practical guidelines for out-of-hospital ventilation that are in accordance with specific Austrian framework parameters and legal foundations. The guidelines are oriented toward a 2004 consensus ÖGP recommendation concerning the setup of long-term ventilated patients and the 2010 German Respiratory Society S2 guidelines on noninvasive and invasive ventilation of chronic respiratory insufficiency, adapted to national experiences and updated according to recent literature. In 11 chapters, the initiation, adjustment, and monitoring of out-of-hospital ventilation is described, as is the technical equipment and airway access. Additionally, the different indications-such as chronic obstructive pulmonary diseases, thoracic restrictive and neuromuscular diseases, obesity hypoventilation syndrome, and pediatric diseases-are discussed. Furthermore, the respiratory physiotherapy of adults and children on invasive and noninvasive long-term ventilation is addressed in detail.

Prognostic Value of Initial Assessment of Residual Hypoventilation Using Nocturnal Capnography in Mechanically Ventilated Neuromuscular Patients: A 5-Year Follow-up Study

Background

Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, and its efficiency is mostly assessed by daytime blood gases or nocturnal oxygen saturation monitoring (SpO₂). Non-invasive transcutaneous measure of CO₂ (TcCO₂) allows to directly assess nocturnal hypercapnia and to detect residual hypoventilation with a higher sensitivity than SpO₂. We aimed to compare the prognostic value of nocturnal SpO₂ and TcCO₂ in ventilated adult NMD patients.

Methods

All consecutive capno-oximetries performed between 2010 and 2011 in ventilated adult NMD patients were analyzed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Nocturnal hypoxemia and hypercapnia (using four different definitions) at baseline were compared in their ability to predict mortality and respiratory events requiring ICU admission during follow-up.

Results

Data from 55 patients were analyzed (median age 28 [interquartile range: 25–36.5] years; 71% Duchenne muscular dystrophy; vital capacity 12 [7–27]% of predicted; 51% tracheostomy). Capno-oxymetry showed hypoxemia in 14.5% and hypercapnia in 12.7–41.8%, according to the used definition. Over a follow-up lasting up to 5 years (median 4.0 [3.6–4.5] years), we observed 12 deaths and 20 respiratory events requiring ICU admission. Hypercapnia was significantly associated with the study outcomes, with TcCO₂ > 49 mmHg during ≥10% of the time being the best definition, while hypoxemia was not.

Conclusion

Our data show for the first time that residual hypoventilation, assessed by capnometry, is significantly associated with negative outcomes in adult ventilated NMD patients, while oximetry is not. Accordingly, we suggest capnometry to be included in the systematic assessment of HMV efficiency in NMD patients.

ClinicalTrials.gov Identifier

NCT02551406.

Spinal Muscular Atrophy

Spinal muscular atrophy is an autosomal-recessive disorder characterized by degeneration of motor neurons in the spinal cord and caused by mutations in the survival motor neuron 1 gene, SMN1. The severity of SMA is variable. The SMN2 gene produces a fraction of the SMN messenger RNA (mRNA) transcript produced by the SMN1 gene. There is an inverse correlation between SMN2 gene copy number and clinical severity. Clinical management focuses on multidisciplinary care. Preclinical models of SMA have led to an explosion of SMA clinical trials that hold great promise of effective therapy in the future.

Nocturnal hypoventilation in neuromuscular disease: prevalence according to different definitions issued from the literature

PURPOSE

Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, identified by daytime hypercapnia or nocturnal desaturation. Recently, transcutaneous measure of CO2 (TcCO2) has been increasingly used to detect hypoventilation, using different cut-offs. We aimed to compare the prevalence of hypoventilation in an unselected adult NMD population according to different definitions issued from the literature.

METHODS

All consecutive nocturnal capno-oximetries performed between 2010 and 2014 in unventilated adult NMD patients were analysed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Hypoventilation was defined according to eight criteria, based on daytime PaCO2, daytime base excess, nocturnal SpO2 or TcCO2.

RESULTS

Data from 232 patients were analysed (mean age 43.1 ± 15.4 years; 50.0 % women; vital capacity 59.2 ± 24.2 % of predicted). The hypoventilation prevalence was 10.3 to 61.2 %, depending on the used definition. The different definitions showed 49.1 to 94.8 % concordance (Cohen's kappa for agreement 0.115 to 0.763). Overall agreement between the eight definitions was poor (Light's kappa 0.267), and agreement between definitions based on nocturnal SpO2 and those based on TcCO2 was even lower (Light's kappa 0.204).

CONCLUSIONS

We found large differences in hypoventilation prevalence according to the used definition. This has practical consequences, as HMV indication relies upon hypoventilation detection. We believe that capno-oximetry should be included in the diagnostic tools used to detect hypoventilation but this requires an update of consensus guidelines to agree upon the best definition.

Chronic hypoventilation syndromes and sleep-related hypoventilation

Chronic hypoventilation affects patients with disorders on any level of the respiratory system. The generation of respiratory impulses can be impaired in congenital disorders, such as central congenital alveolar hypoventilation, in alterations of the brain stem or complex diseases like obesity hypoventilation. The translation of the impulses via spinal cord and nerves to the respiratory muscles can be impaired in neurological diseases. Thoraco-skeletal or muscular diseases may inhibit the execution of the impulses. All hypoventilation disorders are characterized by a reduction of the minute ventilation with an increase of daytime hypercapnia. As sleep reduces minute ventilation substantially in healthy persons and much more pronounced in patients with underlying thoraco-pulmonary diseases, hypoventilation manifests firstly during sleep. Therefore, sleep related hypoventilation may be an early stage of chronic hypoventilation disorders. After treatment of any prevailing underlying disease, symptomatic therapy with non-invasive ventilation (NIV) is required. The adaptation of the treatment should be performed under close medical supervision. Pressure support algorithms have become most frequently used. The most recent devices automatically apply pressure support and vary inspiratory and expiratory pressures and breathing frequency in order to stabilize upper airways, normalize ventilation, achieve best synchronicity between patient and device and aim at optimizing patients' adherence.

Spinal muscular atrophy: diagnosis and management in a new therapeutic era

Spinal muscular atrophy (SMA) describes a group of disorders associated with spinal motor neuron loss. In this review we provide an update regarding the most common form of SMA, proximal or 5q-SMA, and discuss the contemporary approach to diagnosis and treatment. Electromyography and muscle biopsy features of denervation were once the basis for diagnosis, but molecular testing for homozygous deletion or mutation of the SMN1 gene allows efficient and specific diagnosis. In combination with loss of SMN1, patients retain variable numbers of copies of a second similar gene, SMN2, which produces reduced levels of the survival motor neuron (SMN) protein that are insufficient for normal motor neuron function. Despite the fact that understanding of how ubiquitous reduction of SMN protein leads to motor neuron loss remains incomplete, several promising therapeutics are now being tested in early-phase clinical trials.

Non-invasive ventilation in the treatment of sleep-related breathing disorders: A review and update

Non-invasive mechanical ventilation (NIV) was originally used in patients with acute respiratory compromises or exacerbations of chronic respiratory diseases as an alternative to intubation. Over the last thirty years NIV has been used during the night in patients with stable chronic lung diseases such as obstructive sleep apnea, the overlap syndrome (COPD and obstructive sleep apnea), neuromuscular disorders, obesity-hypoventilation syndrome and in other conditions such as sleep disorders associated with congestive heart failure. In this review we discuss the different types of NIV, the specific conditions in which they can be used as well as the indications, recommendations, and evidence supporting the efficacy of NIV.

New modalities for non-invasive ventilation

There is now substantial evidence supporting the use of non-invasive ventilation in acute hypercpanic exacerbations of chronic respiratory failure, and early trials show nocturnal ventilatory support may benefit chronic heart failure patients with sleep disordered breathing. Attention is now being focused on innovative modes which adapt respiratory support to the user's ventilatory pattern, eg adaptive service ventilation and assured volume delivery 'intelligent' ventilation.

Gas exchange in disease: asthma, chronic obstructive pulmonary disease, cystic fibrosis, and interstitial lung disease

Ventilation-perfusion (VA/Q) inequality is the underlying abnormality determining hypoxemia and hypercapnia in lung diseases. Hypoxemia in asthma is characterized by the presence of low VA/Q units, which persist despite improvement in airway function after an attack. This hypoxemia is generally attenuated by compensatory redistribution of blood flow mediated by hypoxic vasoconstriction and changes in cardiac output, however, mediator release and bronchodilator therapy may cause deterioration. Patients with chronic obstructive pulmonary disease have more complex patterns of VA/Q inequality, which appear more fixed, and changes in blood flow and ventilation have less benefit in improving gas exchange efficiency. The inability of ventilation to match increasing cardiac output limits exercise capacity as the disease progresses. Deteriorating hypoxemia during exacerbations reflects the falling mixed venous oxygen tension from increased respiratory muscle activity, which is not compensated by any redistribution of VA/Q ratios. Shunt is not a feature of any of these diseases. Patients with cystic fibrosis (CF) have no substantial shunt when managed according to modern treatment regimens. Interstitial lung diseases demonstrate impaired oxygen diffusion across the alveolar-capillary barrier, particularly during exercise, although VA/Q inequality still accounts for most of the gas exchange abnormality. Hypoxemia may limit exercise capacity in these diseases and in CF. Persistent hypercapnic respiratory failure is a feature of advancing chronic obstructive pulmonary disease and CF, closely associated with sleep disordered breathing, which is not a prominent feature of the other diseases. Better understanding of the mechanisms of hypercapnic respiratory failure, and of the detailed mechanisms controlling the distribution of ventilation and blood flow in the lung, are high priorities for future research.

The role of respiratory management of Pompe disease

Respiratory failure is an unavoidable event in the natural history of some neuromuscular diseases, while appearing very infrequently in others. In some cases, such as Pompe disease, respiratory failure progresses more rapidly than motor impairment, sometimes being the onset event. Home mechanical ventilation improves survival and quality of life of these patients, with a reduction in healthcare costs. Therefore, pulmonologists must improve their skills in order to play a more relevant role in the care of these patients. The aim of this statement is to provide pulmonologists with some simple information in order for them to fulfil their role of primary caregiver, enabling appropriate and rapid diagnosis and treatment.