Michelle Chatwin

Randomised controlled trial of non-invasive ventilation (NIV) for nocturnal hypoventilation in neuromuscular and chest wall disease patients with daytime normocapnia

Background: Long term non-invasive ventilation (NIV) reduces morbidity and mortality in patients with neuromuscular and chest wall disease with hypercapnic ventilatory failure, but preventive use has not produced benefit in normocapnic patients with Duchenne muscular dystrophy. Individuals with nocturnal hypercapnia but daytime normocapnia were randomised to a control group or nocturnal NIV to examine whether nocturnal hypoventilation is a valid indication for NIV. Methods: Forty eight patients with congenital neuromuscular or chest wall disease aged 7–51 years and vital capacity <50% predicted underwent overnight respiratory monitoring. Twenty six with daytime normocapnia and nocturnal hypercapnia were randomised to either nocturnal NIV or to a control group without ventilatory support. NIV was started in the control group if patients fulfilled preset safety criteria. Results: Peak nocturnal transcutaneous carbon dioxide tension (Tcco2) did not differ between the groups, but the mean (SD) percentage of the night during which Tcco2 was >6.5 kPa decreased in the NIV group (−57.7 (26.1)%) but not in controls (−11.75 (46.1)%; p = 0.049, 95% CI −91.5 to −0.35). Mean (SD) arterial oxygen saturation increased in the NIV group (+2.97 (2.57)%) but not in controls (−1.12 (2.02)%; p = 0.024, 95% CI 0.69 to 7.5). Nine of the 10 controls failed non-intervention by fulfilling criteria to initiate NIV after a mean (SD) of 8.3 (7.3) months. Conclusion: Patients with neuromuscular disease with nocturnal hypoventilation are likely to deteriorate with the development of daytime hypercapnia and/or progressive symptoms within 2 years and may benefit from the introduction of nocturnal NIV before daytime hypercapnia ensues.

Cough augmentation with mechanical insufflation/exsufflation in patients with neuromuscular weakness

Adults and children with neuromuscular disease exhibit weak cough and are susceptible to recurrent chest infections, a major cause of morbidity and mortality. Mechanical insufflation/exsufflation may improve cough efficacy by increasing peak cough flow. It was hypothesised that mechanical insufflation/exsufflation would produce a greater increase in peak cough flow than other modes of cough augmentation. The acceptability of these interventions was also compared. Twenty-two patients aged 10–56 yrs (median 21 yrs) with neuromuscular disease and 19 age-matched controls were studied. Spirometry was performed and respiratory muscle strength measured. Peak cough flow was recorded during maximal unassisted coughs, followed in random order by coughs assisted by physiotherapy, noninvasive ventilation, insufflation and exsufflation, and exsufflation alone. Subjects rated strength of cough, distress and comfort on a visual analogue scale. In the neuromuscular disease group, mean±sd forced expiratory volume in one second was 0.8±0.6 L·s−1, forced vital capacity 0.9±0.8 L, maximum inspiratory pressure 25±16 cmH2O, maximum expiratory pressure 26±22 cmH2O and unassisted peak cough flow 169±90 L·min−1. The greatest increase in peak cough flow was observed with mechanical insufflation/exsufflation at 235±111 L·min−1 (p<0.01). All techniques showed similar patient acceptability. Mechanical insufflation/exsufflation produces a greater increase in peak cough flow than other standard cough augmentation techniques in adults and children with neuromuscular disease.

British Thoracic Society guideline for respiratory management of children with neuromuscular weakness

The British Thoracic Society guideline for respiratory management of children with neuromuscular weakness summarises the available evidence in this field and provides recommendations that will aid healthcare professionals in delivering good quality patient care.

Outcome of goal-directed non-invasive ventilation and mechanical insufflation/exsufflation in spinal muscular atrophy type I

Background There are widely discrepant views on the respiratory management of infants with spinal muscular atrophy (SMA) type I. Typically, management is palliative. Design A descriptive study of interventions and investigations is reported that were offered to a cohort of 13 children with SMA type I referred to our centre. Interventions and investigations included sleep studies, provision of non-invasive positive pressure ventilation (NIPPV) for ventilatory support/dependency and for physiotherapy and the use of mechanical insufflation/exsufflation (MI-E). Results NIPPV was provided for the following indications: continuous positive airways pressure flow driver dependency (n=3), nocturnal hypoventilation (n=3), to enable successful extubation (n=2), in anticipation of respiratory decompensation (n=3), and oxygen dependency/decompensation (n=2). NIPPV and MI-E were used for successful protocol-led extubations (n=9) but not non protocol-led successes (n=3). NIPPV was essential for discharge home in patients with ventilatory dependency (n=7) and was used for palliation of respiratory symptoms (n=4). Chest wall shape improved with NIPPV. The parents of children who died (n=5) were positive about the use of these techniques. Conclusion NIPPV can be used to facilitate discharge home, and MI-E is helpful in this group. This symptom and goal-directed approach can be used to inform medical decision making and to help parents make informed choices about the appropriateness of respiratory interventions in SMA type I.

Randomised trial of inpatient versus outpatient initiation of home mechanical ventilation in patients with nocturnal hypoventilation

BACKGROUND Long-term home mechanical ventilation (HMV) is usually initiated in hospital. Admission to hospital has resource implications and may not be reimbursable in some healthcare systems. METHODS Twenty-eight stable neuromuscular and chest wall disease patients with nocturnal hypoventilation (transcutaneous carbon dioxide (TcCO(2) >6.5 kPa), were randomised to start HMV either as an outpatient (n=14, age range 12-62 years) or inpatient (n=14, age range 14-73 years). We compared effects of HMV on nocturnal and diurnal arterial blood gas tensions, ventilator compliance, healthcare professional (HCP) contact time, and time in hospital. RESULTS Improvements in nocturnal arterial oxygen saturation (SaO(2)) and daytime PaO(2) were equivalent in both groups. Peak nocturnal TcCO(2), improved in both groups; % time TcCO(2) >6.5 kPa fell in the inpatient group and daytime PaCO(2) decreased significantly (p<0.05) in the outpatient group. The mean (SD) inpatient stay was 3.8 (1.0) days, and the outpatient attendance sessions 1.2 (0.4). HCP contact time including telephone calls was: inpatient 177 (99) min; outpatient 188 (60) min (p=not significant); 2 month ventilator compliance was: inpatient 4.32 (7); outpatient 3.92 (8) (p=not significant) hours per night. CONCLUSION Outpatient initiation of HMV is feasible with equivalent outcome in the outpatient and the inpatient groups.

Analysis of home support and ventilator malfunction in 1,211 ventilator-dependent patients

Risk management is an important aspect of home ventilation (HV). We examined the nature of calls to a home support helpline to identify patient/equipment problems and strategies to minimise risk for patients, healthcare teams and manufacturers. From 1,211 adult and paediatric patients with neuromuscular disease, chronic obstructive pulmonary disease or chest wall disease receiving HV, all calls to a dedicated respiratory support telephone hotline between January 1, 2006 and June 30, 2006 were analysed. 1,199 patients received noninvasive ventilation, 12 tracheostomy ventilation; 149 had two ventilators for 24-h ventilator dependency. There was a mean of 528 daytime calls per month and 14 calls a month at night. Following 188 calls, a home visit was performed; these identified a technical problem that could either be solved in the patients home in 64% or required replacement or new parts in 22% of cases. In 25 calls in which no mechanical fault was identified, 13 patients were either found to be unwell or required hospital admission. Patients using HV have a substantial requirement for assistance, with most technical problems being resolved simply. Where no fault can be found during an equipment check, the patient themselves may be unwell and should receive early clinical evaluation. The patient may have mistaken clinical deterioration for an equipment problem.

Autotitrating versus standard noninvasive ventilation: a randomised crossover trial

The aim of the present study was to compare the efficacy of automatic titration of noninvasive ventilation (NIV) with conventional NIV in stable neuromuscular and chest wall disorder patients established on long-term ventilatory support. In total, 20 neuromuscular and chest wall disease patients with nocturnal hypoventilation treated with long-term NIV completed a randomised crossover trial comparing two noninvasive pressure support ventilators: a standard bilevel ventilator (VPAP III) and a novel autotitrating bilevel ventilator (AutoVPAP). Baseline physiological measurements, overnight polysomnography and Holter monitoring were repeated at the end of each 1-month treatment period. Nocturnal oxygenation was comparable between the autotitrating device and standard ventilator, as were sleep efficiency, arousals and heart rate variability. However, there was a small significant increase in mean overnight transcutaneous carbon dioxide tension (median (interquartile range) 7.2 (6.7–7.7) versus 6.7 (6.1–7.0) kPa) and a decrease in percentage stage 1 sleep (mean±sd 16±9 versus 19±10%) on autotitrating NIV compared with conventional NIV. Autotitrating noninvasive ventilation using AutoVPAP produced comparable control of nocturnal oxygenation to standard nonivasive ventilation, without compromising sleep quality in stable neuromuscular and chest wall disease patients requiring long-term ventilatory support for nocturnal hypoventilation.

Evaluation of droplet dispersion during non-invasive ventilation, oxygen therapy, nebuliser treatment and chest physiotherapy in clinical practice: implications for management of pandemic influenza and other airborne infections.

BACKGROUND Influenza viruses are thought to be spread by droplets, but the role of aerosol dissemination is unclear and has not been assessed by previous studies. Oxygen therapy, nebulised medication and ventilatory support are treatments used in clinical practice to treat influenzal infection are thought to generate droplets or aerosols. OBJECTIVES Evaluation of the characteristics of droplet/aerosol dispersion around delivery systems during non-invasive ventilation (NIV), oxygen therapy, nebuliser treatment and chest physiotherapy by measuring droplet size, geographical distribution of droplets, decay in droplets over time after the interventions were discontinued. METHODS Three groups were studied: (1) normal controls, (2) subjects with coryzal symptoms and (3) adult patients with chronic lung disease who were admitted to hospital with an infective exacerbation. Each group received oxygen therapy, NIV using a vented mask system and a modified circuit with non-vented mask and exhalation filter, and nebulised saline. The patient group had a period of standardised chest physiotherapy treatment. Droplet counts in mean diameter size ranges from 0.3 to > 10 µm were measured with an counter placed adjacent to the face and at a 1-m distance from the subject/patient, at the height of the nose/mouth of an average health-care worker. RESULTS NIV using a vented mask produced droplets in the large size range (> 10 µm) in patients (p = 0.042) and coryzal subjects (p = 0.044) compared with baseline values, but not in normal controls (p = 0.379), but this increase in large droplets was not seen using the NIV circuit modification. Chest physiotherapy produced droplets predominantly of > 10 µm (p = 0.003), which, as with NIV droplet count in the patients, had fallen significantly by 1 m. Oxygen therapy did not increase droplet count in any size range. Nebulised saline delivered droplets in the small- and medium-size aerosol/droplet range, but did not increase large-size droplet count. CONCLUSIONS NIV and chest physiotherapy are droplet (not aerosol)-generating procedures, producing droplets of > 10 µm in size. Due to their large mass, most fall out on to local surfaces within 1 m. The only device producing an aerosol was the nebuliser and the output profile is consistent with nebuliser characteristics rather than dissemination of large droplets from patients. These findings suggest that health-care workers providing NIV and chest physiotherapy, working within 1 m of an infected patient should have a higher level of respiratory protection, but that infection control measures designed to limit aerosol spread may have less relevance for these procedures. These results may have infection control implications for other airborne infections, such as severe acute respiratory syndrome and tuberculosis, as well as for pandemic influenza infection.

Long term non-invasive ventilation in children: impact on survival and transition to adult care.

Background The number of children receiving domiciliary ventilatory support has grown over the last few decades driven largely by the introduction and widening applications of non-invasive ventilation. Ventilatory support may be used with the intention of increasing survival, or to facilitate discharge home and/or to palliate symptoms. However, the outcome of this intervention and the number of children transitioning to adult care as a consequence of longer survival is not yet clear. Methods In this retrospective cohort study, we analysed the outcome in children (<17 years) started on home NIV at Royal Brompton Hospital over an 18 year period 1993-2011. The aim was to establish for different diagnostic groups: survival rate, likelihood of early death depending on diagnosis or discontinuation of ventilation, and the proportion transitioning to adult care. Results 496 children were commenced on home non invasive ventilation; follow-up data were available in 449 (91%). Fifty six per cent (n=254) had neuromuscular disease. Ventilation was started at a median age (IQR) 10 (3-15) years. Thirteen percent (n=59) were less than 1 year old. Forty percent (n=181) have transitioned to adult care. Twenty four percent (n=109) of patients have died, and nine percent (n=42) were able to discontinue ventilatory support. Conclusion Long term ventilation is associated with an increase in survival in a range of conditions leading to ventilatory failure in children, resulting in increasing numbers surviving to adulthood. This has significant implications for planning transition and adult care facilities.

Randomized trial of 'intelligent' autotitrating ventilation versus standard pressure support non-invasive ventilation: impact on adherence and physiological outcomes.

Effective non‐invasive ventilation (NIV) therapy is dependent on optimal ventilator settings to maximize clinical benefit and patient tolerance. Intelligent volume‐assured pressure support (iVAPS) is a hybrid mode of servoventilation, providing constant automatic adjustment of pressure support (PS) to achieve a target ventilation determined by the patients requirements. In a randomized crossover trial, we tested the hypothesis that iVAPS, with automated selection of ventilator settings, was non‐inferior to standard PS ventilation, with settings determined by an experienced health‐care professional, for controlling nocturnal hypoventilation in patients naive to NIV.