Volume targeted versus pressure support non-invasive ventilation in patients with super obesity and chronic respiratory failure: a randomised controlled trial

INTRODUCTION

Automatic titration modes of non-invasive ventilation, including average volume assured pressure support (AVAPS), are hybrid technologies that target a set volume by automated adjustment of pressure support (PS). These automated modes could offer potential advantages over fixed level PS, in particular, in patients who are super obese.

METHODS

Consecutive patients with obesity hypoventilation syndrome were enrolled in a two-centre prospective single-blind randomised controlled trial of AVAPS versus fixed-level PS using a strict protocolised setup.

MEASUREMENTS

The primary outcome was change in daytime arterial PCO(2) (PaCO(2)) at 3 months. Body composition, physical activity (7-day actigraphy) and health-related quality of life (severe respiratory insufficiency questionnaire, SRI) were secondary outcome measures.

RESULTS

50 patients (body mass index 50±7 kg/m(2); 55±11 years; 53% men) were enrolled with a mean PaCO(2) of 6.9±0.8 kPa and SRI of 53±17. 46 patients (23 AVAPS and 23 PS) completed the trial. At 3 months, improvements in PaCO(2) were observed in both groups (AVAPS 0.6 kPa, 95% CI 0.2 to 1.1, p<0.01 vs PS 0.6 kPa, 95% CI 0.1 to 1.1, p=0.02) but no between-group difference (-0.1 kPa, 95% CI -0.7 to 0.6, p=0.87). SRI also improved in both groups (AVAPS 11, 95% CI 6 to 17, p<0.001 vs PS 7, 95% CI 1 to 12, p=0.02; between groups 5, 95% CI -3 to 12, p=0.21). Secondary analysis of both groups combined showed improvements in daytime physical activity that correlated with reduction in fat mass (r=0.48; p=0.01).

CONCLUSION

The study demonstrated no differences between automated AVAPS mode and fixed-level PS mode using a strict protocolised setup in patients who were super obese. The data suggest that the management of sleep-disordered breathing may enhance daytime activity and promote weight loss in super-obese patients.

Consensus statement on standard of care for congenital muscular dystrophies

Congenital muscular dystrophies are a group of rare neuromuscular disorders with a wide spectrum of clinical phenotypes. Recent advances in understanding the molecular pathogenesis of congenital muscular dystrophy have enabled better diagnosis. However, medical care for patients with congenital muscular dystrophy remains very diverse. Advances in many areas of medical technology have not been adopted in clinical practice. The International Standard of Care Committee for Congenital Muscular Dystrophy was established to identify current care issues, review literature for evidence-based practice, and achieve consensus on care recommendations in 7 areas: diagnosis, neurology, pulmonology, orthopedics/rehabilitation, gastroenterology/ nutrition/speech/oral care, cardiology, and palliative care. To achieve consensus on the care recommendations, 2 separate online surveys were conducted to poll opinions from experts in the field and from congenital muscular dystrophy families. The final consensus was achieved in a 3-day workshop conducted in Brussels, Belgium, in November 2009. This consensus statement describes the care recommendations from this committee.

Interfamilial phenotypic heterogeneity in SMARD1

Spinal muscular atrophy with respiratory distress (SMARD1: mu-binding protein 2 gene mutation) is characterised by low birth weight, progressive distal limb weakness, diaphragmatic paralysis and subsequent respiratory failure manifesting before 13 months of age. Our case report illustrates marked phenotype variability in two siblings with an identical genetic mutation of SMARD1, one of whom died of fulminant respiratory failure aged 6 months, whereas the other shows limb weakness but, only mild sleep hypoventilation aged 12 years. This suggests other compensatory mechanisms may play a role in modifying SMARD1; broadening our perception of phenotype. Therefore, SMARD1 phenotype should be considered in cases of atypical spinal muscular atrophy even in the absence of overt diaphragmatic weakness.

Mechanisms of improvement of respiratory failure in patients with COPD treated with NIV

Background

Noninvasive ventilation (NIV) improves gas-exchange and symptoms in selected chronic obstructive pulmonary disease (COPD) patients with hypercapnic respiratory failure. We hypothesized NIV reverses respiratory failure by one or all of increased ventilatory response to carbon-dioxide, reduced respiratory muscle fatigue, or improved pulmonary mechanics.

Methods

Nineteen stable COPD patients (forced expiratory volume in one second 35% predicted) were studied at baseline (D0), 5–8 days (D5) and 3 months (3M) after starting NIV.

Results

Ventilator use was 6.2 (3.7) hours per night at D5 and 3.4 (1.6) at 3M (p = 0.12). Mean (SD) daytime arterial carbon-dioxide tension (PaCO₂) was reduced from 7.4 (1.2) kPa to 7.0 (1.1) kPa at D5 and 6.5 (1.1) kPa at 3M (p = 0.001). Total lung capacity decreased from 107 (28) % predicted to 103 (28) at D5 and 103 (27) % predicted at 3M (p = 0.035). At D5 there was an increase in the hypercapnic ventilatory response and some volitional measures of inspiratory and expiratory muscle strength, but not isolated diaphragmatic strength whether assessed by volitional or nonvolitional methods.

Conclusion

These findings suggest decreased gas trapping and increased ventilatory sensitivity to CO₂ are the principal mechanism underlying improvements in gas-exchange in patients with COPD following NIV. Changes in some volitional but not nonvolitional muscle strength measures may reflect improved patient effort.

End-of-life decision-making in respiratory intermediate care units: a European survey

A survey was performed on behalf of the European Respiratory Society to assess end-of-life practices in patients admitted to European respiratory intermediate care units and high dependency units over a 6-month period. A 33-item questionnaire was sent by e-mail to physicians throughout Europe and the response rate was 28 (29.5%) out of 95. A total of 6,008 patients were admitted and an end-of-life decision was taken in 1,292 (21.5%). The mortality rate in these patients was 68% (884 out of 1,292). The patients received similar proportions of withholding of treatment (298 (23%) out of 1292), do-not-resuscitate or do-not-intubate orders (442 (34%) out of 1,292) and noninvasive mechanical ventilation as the ceiling of ventilatory care (402 (31%) out of 1,292). Withdrawal of therapy was employed in 149 (11%) out of 1,292 patients and euthanasia in one. Do-not-intubate/do-not-resuscitate orders were more frequently used in North compared with South Europe. All of the 473 competent patients directly participated in the decision, whereas, in 722 (56%) out of 1,292 cases, decision-making was reported to be shared with the nurses. In European respiratory intermediate care units and high dependency units, an end-of-life decision is taken for 21.5% of patients admitted. Withholding of treatment, do-not-intubate/do-not-resuscitate orders and noninvasive mechanical ventilation as the ventilatory care ceiling are the most common procedures. Competent patients are often involved, together with nurses.

The clinical management in extremely severe COPD

Chronic obstructive pulmonary disease (COPD) affects 6% of the general population and is the fourth-leading cause of death in the United States with severe and very severe disease accounting for 15% and 3% of physician diagnoses of COPD. Guidelines make few recommendations regarding providing the provision of care for the most severe stages of disease, namely Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages III and IV with chronic respiratory failure. The effectiveness of inhaled drug therapy in very severe patients has not been assessed yet. Health care systems in many countries include public funding of long-term oxygen therapy for eligible candidates. Currently, there is little evidence for the use of mechanical ventilatory support in the routine management of hypercapnic patients. Pulmonary rehabilitation should be considered as a significant component of therapy, even in the most severe patients. Although Lung Volume Reduction Surgery has been shown to improve mortality, exercise capacity, and quality of life in selected patients, this modality is associated with significant morbidity and an early mortality rate in the most severe patients. Despite significant progress over the past 25 years, both short- and long-term outcomes remain significantly inferior for lung transplantation relative to other "solid" organ recipients. Nutritional assessment and management is an important therapeutic option in patients with chronic respiratory diseases. Morphine may significantly reduce dyspnoea and does not significantly accelerate death. No consistent improvement in dyspnoea over placebo has been shown with anxiolytics. Supplemental oxygen during exercise reduces exertional breathlessness and improves exercise tolerance of the hypoxaemic patient. Non-invasive ventilation has been used as a palliative treatment to reduce dyspnoea. Hypoxaemic COPD patients, on long-term oxygen therapy, may show reduced health-related quality of life, cognitive function, and depression. Only a small proportion of patients with severe COPD discuss end-of-life issues with their physicians.

Consensus statement for standard of care in spinal muscular atrophy

Spinal muscular atrophy is a neurodegenerative disease that requires multidisciplinary medical care. Recent progress in the understanding of molecular pathogenesis of spinal muscular atrophy and advances in medical technology have not been matched by similar developments in the care for spinal muscular atrophy patients. Variations in medical practice coupled with differences in family resources and values have resulted in variable clinical outcomes that are likely to compromise valid measure of treatment effects during clinical trials. The International Standard of Care Committee for Spinal Muscular Atrophy was formed in 2005, with a goal of establishing practice guidelines for clinical care of these patients. The 12 core committee members worked with more than 60 spinal muscular atrophy experts in the field through conference calls, e-mail communications, a Delphi survey, and 2 in-person meetings to achieve consensus on 5 care areas: diagnostic/new interventions, pulmonary, gastrointestinal/nutrition, orthopedics/rehabilitation, and palliative care. Consensus was achieved on several topics related to common medical problems in spinal muscular atrophy, diagnostic strategies, recommendations for assessment and monitoring, and therapeutic interventions in each care area. A consensus statement was drafted to address the 5 care areas according to 3 functional levels of the patients: nonsitter, sitter, and walker. The committee also identified several medical practices lacking consensus and warranting further investigation. It is the authors' intention that this document be used as a guideline, not as a practice standard for their care. A practice standard for spinal muscular atrophy is urgently needed to help with the multidisciplinary care of these patients.

Respiratory management of the infant with type 1 spinal muscular atrophy

A recent paper has highlighted the differences in the respiratory management offered to infants with type 1 spinal muscular atrophy (SMA-1). Current views appear polarised between those who would offer nothing, to those who would proceed as far even as tracheostomy and long term invasive ventilation for these infants. Here we offer a personal view, as a possible template for managing a vexed and emotional problem. The complex non-respiratory aspects of the holistic care of these infants will not be discussed.

Quality control of equipment in home mechanical ventilation: a European survey

Quality control of the equipment used in home mechanical ventilation is necessary in order to ensure that patients safely and accurately receive the prescribed ventilatory support. The aim of this study was to carry out a survey on the quality-control procedures in different centres and countries. The survey was carried out in the context of a European Commission Concerted Action covering 16 European countries. The study was extensive and detailed, involving 326 centres, which provided home ventilation to >20,000 patients. The survey showed that: 1) ventilator servicing was mainly carried out by external companies (62% of centres), with a servicing frequency ranging 3-12 months; 2) interaction between servicing companies and prescribers was limited (only 61% of centres were always informed of major incidents); 3) participation of centres in equipment quality control was poor (only 56% of centres assessed that patients/caregivers correctly cleaned/maintained the ventilator); and 4) centres were insufficiently aware of vigilance systems (only 23% of centres). Moreover, the data showed considerable inter- and intra-country differences. The size of the centre was an important determinant of many of these quality-control aspects. This survey provides information that will enable the European Commission Concerted Action to formulate recommendations on procedures for home-ventilator quality control.

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

BACKGROUND

Nocturnal non-invasive ventilation (NIV) is an effective treatment for hypercapnic respiratory failure in patients with restrictive thoracic disease. We hypothesised that NIV may reverse respiratory failure by increasing the ventilatory response to carbon dioxide, reducing inspiratory muscle fatigue, or enhancing pulmonary mechanics.

METHODS

Twenty patients with restrictive disease were studied at baseline (D0) and at 5-8 days (D5) and 3 months (3M).

RESULTS

Mean (SD) daytime arterial carbon dioxide tension (Paco(2)) was reduced from 7.1 (0.9) kPa to 6.6 (0.8) kPa at D5 and 6.3 (0.9) kPa at 3M (p = 0.004), with the mean (SD) hypercapnic ventilatory response increasing from 2.8 (2.3) l/min/kPa to 3.6 (2.4) l/min/kPa at D5 and 4.3 (3.3) l/min/kPa at 3M (p = 0.044). No increase was observed in measures of inspiratory muscle strength including twitch transdiaphragmatic pressure, nor in lung function or respiratory system compliance.

CONCLUSIONS

These findings suggest that increased ventilatory response to carbon dioxide is the principal mechanism underlying the long term improvement in gas exchange following NIV in patients with restrictive thoracic disease. Increases in respiratory muscle strength (sniff oesophageal pressure and sniff nasal pressure) correlated with reductions in the Epworth sleepiness score, possibly indicating an increase in the ability of patients to activate inspiratory muscles rather than an improvement in contractility.

Kyphoscoliosis and bronchial torsion

STUDY OBJECTIVE

Severe idiopathic scoliosis is associated with respiratory failure. This usually is secondary to restrictive airway disease and reduced vital capacity. Patients may also suffer from an increase in airway resistance when severe kyphoscoliosis is present.

SETTING

Three patients (two of whom required assisted ventilation) with varying degrees of kyphoscoliosis presented with moderate to severe breathing difficulties.

INTERVENTION

Bronchoscopic examination of these patients showed evidence of torsion with secondary obstruction of the central airways.

RESULTS

The airway obstruction was notable for its slit-like appearance, for the normality of the mucosa at the site of the obstruction, for the relative ease through which an instrument could traverse the obstruction, and once the retained secretions had been cleared, for the preservation of normal anatomy of the distal airways. The insertion of metal prostheses to stent the areas of obstruction prompted an impressive improvement in respiratory status, radiologic findings, and spirometric criteria in each case. Improvement has been maintained over a maximum follow-up period of 4 years.

CONCLUSION

Severe kyphoscoliosis can lead to bronchial torsion and obstruction of the central airways. Patients should be assessed by bronchoscopy to exclude this deformity or any other cause of obstruction. The use of a metal endobronchial stent has been effective in both the immediate and long-term period.

Short-term use of fluoxetine in asymptomatic obese subjects with sleep-related hypoventilation

Disordered nocturnal breathing with significant arterial oxygen desaturation and sleep apnoea is a feature of extreme obesity which is often difficult to manage in the short term. We have evaluated the effect of fluoxetine, a centrally acting 5-HT re-uptake inhibitor, on sleep-breathing patterns in asymptomatic extremely obese subjects. A double-blind cross-over study was used to compare fluoxetine (60 mg for three days) to placebo. Eleven obese subjects (ten males, one female, mean weight +/- s.d. 131 +/- 2 kg) slept overnight in a sleep laboratory with the polysomnographic study recorded after an initial acclimatization night. The obese subjects had normal respiratory function and normal fully awake arterial oxygen saturation (%SaO2 97 +/- 1). Marked O2 desaturation was seen in all the subjects during sleep but the average asleep %SaO2 did not differ between the two treatment phases (placebo 90 +/- 5; fluoxetine 92 + 2%). However, fluoxetine significantly increased the minimum %SaO2 recorded during the study night either by abolishing or reducing REM sleep (placebo 73 +/- 2%; fluoxetine 81 +/- 8%; P < 0.05, 95% CI -12.3 to -2.03). Frequent hypopnoea was observed in all subjects in both REM and non-REM sleep whereas apnoea was uncommon. The total apnoea/hypopnoea index fell in six subjects during the fluoxetine night, the largest reduction being seen in the most severely affected. In five of the six the improvement was associated with the abolition of REM sleep. Total sleep time did not differ between the placebo and fluoxetine nights nor did a qualitative assessment of sleep using a visual analogue score.(ABSTRACT TRUNCATED AT 250 WORDS)