Introduction

Children requiring long-term ventilation (LTV) are defined as those “who when medically stable, continue to require a mechanical aid for breathing, after an acknowledged failure to wean, or are slow to wean, three months after the institution of ventilation” [8]. The number of children receiving long-term ventilation in the UK has increased over the past 20 years. This can be ascribed to a number of factors including technological advances in diagnosis, suitable medical equipment for use at home, and improved outcomes from critical illnesses [6, 8].

In 1990, a survey in the UK identified 24 children undergoing LTV, of whom nine were cared for at home [11]. In 1997, a questionnaire survey of UK clinicians identified 141 children requiring LTV, with 93 cared for at home [7]. Five of these children were resident in the South West region of the UK. In 2003, a survey undertaken by the South West Regional Paediatric Intensive Care Commissioning group identified 18 children requiring LTV of which 15 were cared for at home (J. Fraser, personal communication). Caring for a child on domiciliary LTV is extremely costly. In 2006, a support package for a child ventilated at home with 24 h care was estimated to cost £239,855 per year [10]. Despite this obvious cost to society and to the wider health care economy, little has been published on the long-term outcome of such patients once home ventilation has been started.

In the South West region of the UK, the management of children on LTV has been centralised for many years, with tertiary respiratory care provided by the Bristol Royal Hospital for Children (BRHC). Children requiring domiciliary LTV are seen in a dedicated multi-professional LTV clinic. The South West has a stable geographical population with a consistent referral pattern. This provides a unique opportunity for prospective evaluation of this group of patients. Since 1981, data have been recorded for all patients receiving invasive and non-invasive LTV, and in 2006, a formal database of all children managed by the team at the BRHC LTV service was established. Evaluation of a well-defined, geographically discrete population can complement data from national surveys; for example, an enhanced ability to track individual patients that allows more precise estimates of changing prevalence over time.

This study examines the increased prevalence of domiciliary LTV in the childhood population of the South West region over a 15-year period and describes underlying disease categories, co-morbidities and the long-term outcome of this group of patients.

Patients and methods

A retrospective review was undertaken of all children who received mechanical ventilation at home in the South West region of the UK, between January 1994 and August 2009. Every child attending LTV clinic has data entered by the LTV nurse specialist. Information from all LTV clinic letters prior to 2006 was used retrospectively to complete the database. Information was collected from the LTV database, medical notes, and the hospital administration system.

Our inclusion criteria were:

  • Children under the age of 18 years at initiation of LTV

  • Managed by the Bristol LTV service

  • Domiciliary LTV electively commenced in hospital, clinic or home.

  • Domiciliary LTV urgently commenced following a failure to wean off acute ventilation instituted during intensive care admission

Children who died in hospital or had ventilatory support discontinued prior to discharge from hospital were excluded from the study.

Data obtained for each patient included dates at which LTV was commenced and ended (where appropriate), diagnoses, outcome, type of ventilation (i.e. invasive or non-invasive), admissions to hospital and intensive care, and hours/day of ventilator dependency. Post code data were used to verify location of residence of patients. Office of National Statistics 2001 census data (most recently published) were used to give a point estimate of the population of young persons under the age of 18 years in the South West. We used a two-tailed Fisher's exact test to compare the outcome between different groups of patients.

Results

Ninety-two patients were referred into the service between 1994 and 2008. The number of new referrals increased between 1994 and 2000 and has fluctuated between four and 20 patients each year since then (Fig. 1). Using 2001 census data for the population under 18 years of age in the South West gives an estimated incidence of 0.6 new patients requiring long-term ventilation per 100,000 child population.

Fig. 1
figure 1

New referrals

In total, 106 patients were managed by the BRHC LTV service during the period of study. In August 2009, 68 children are still currently managed by the paediatric service, 19 have been transferred to the adult LTV service (transfer arrangements beginning at 16 years of age), 11 have died, 6 no longer require LTV, and 2 have moved away from the region.

Between 1994 and 2007, there was an increase each year in the total number of children receiving home ventilation (Fig. 2). In 2008, the total number of home-ventilated children slightly decreased, partly as a result of older patients transitioning into the adult service between the ages of 16 and 20 years. There are six patients, currently managed by the paediatric LTV service, who are resident outside the South West region in South Wales and Wessex. Excluding patients who are resident outside the South West gives an estimated prevalence in 2009 of 6.7 per 100,000 children, compared to 0.2 per 100,000 in 1994.

Fig. 2
figure 2

Number of LTV patients

The use of both invasive (via a tracheostomy) and non-invasive (via a mask) ventilations has changed during the period of study. In recent years, there has been a tendency to commence non-invasive rather than invasive ventilation, with 38 out of the 68 current patients having non-invasive ventilation.

The diagnostic categories for the whole group of 106 patients are shown in Table 1. Airway pathology was the commonest diagnostic category (37 patients), predominantly tracheobronchomalacia (TBM) and obstructive sleep apnoea (OSA). In patients with TBM, 10 out of 15 had associated cardiac disease. Examples of the cardiac conditions encountered include coarctation of the aorta, total anomalous pulmonary venous drainage, double outlet right ventricle with pulmonary stenosis, ventricular septal defect, truncus arteriosus, and pulmonary atresia with multiple aorto-pulmonary collateral arteries. Of the 16 patients with OSA, 11 had neurocognitive disorders including trisomy 21 (3 children) and Prader–Willi syndrome (2 of these children, who were also classified as obese). One patient had OSA solely due to obesity and was transferred to adult services while undergoing a weight management programme. Three children had upper airway obstruction due to skeletal disorders, namely osteogenesis imperfecta, achondroplasia and juvenile arthritis. One child with OSA had no specific diagnosis. The remaining six children with airway pathology were a heterogeneous group that included patients with subglottic stenosis, cranial stenosis, and severe cerebral palsy.

Table 1 Diagnostic categories

Neuromuscular disease was identified in 34 patients–this included 13 children with Duchenne muscular dystrophy, 8 with spinal muscular atrophy, and 5 with nemaline rod myopathy. The remaining 8 children with degenerative neuromuscular conditions include 1 with hereditary motor sensory neuropathy, 1 with myasthenia gravis, 1 with sensory motor polyneuropathy, 1 with congenital fibre-type disproportion, and 4 with as yet undiagnosed conditions.

Central disorders affecting the respiratory drive were present in 33 patients. The most common group was central congenital hypoventilation syndrome (CCHS). Two patients were ventilator dependent following traumatic spinal injury resulting in quadriplegia. The 14 patients with other disorders of central drive are a heterogeneous group of children with severe neurodevelopmental disorders, including trisomy 13, Rett syndrome, cerebral palsy, and mitochondrial disease. Two patients had underlying severe parenchymal lung disease, namely bronchiectasis, and chronic lung disease of unknown aetiology.

There was no significant difference between these broad diagnostic groups in terms of survival or ability to discontinue LTV (Fisher's exact test of discontinuing ventilation, airway versus NMD, p = 0.056). Five of 34 patients with airway disease discontinued LTV versus no patients with neuromuscular disease. The details of patients that no longer require LTV support are shown in Table 2. The mean duration of home ventilation, in these patients, prior to discontinuation of LTV was 32 months (range, 3–59 months). All but one of those discharged had airway pathology as their primary diagnosis. However, these weaned patients are not representative of this diagnostic group, as the remaining 11 patients with TBM have been ventilated for a mean of 47 months and maximum of 12 years. Two children no longer required mechanical ventilation following formation of a tracheostomy.

Table 2 Details of patients discharged from LTV

In total, 11 patients died while receiving LTV, 1 due to complications of ventilation and 10 as a result of conditions associated with their primary diagnosis. Thirty patients are no longer managed by the paediatric LTV service. Nineteen of these have been transferred to the adult home ventilation service. The number of patients transferred to the adult service has steadily increased: 1 per year between 2000 and 2002, 3 per year in 2005 and 2006, 4 in 2007, and 6 in 2008.

Co-morbidity was frequent affecting 69 patients; the most frequent associations were the need for gastrostomy or gastric tube feeds (36 children), mobility problems (35), severe developmental delay (23), epilepsy (11), and cardiac disease (10). All children of school age on LTV are attending school, and children without severe co-morbidities are included in mainstream education, usually with additional support. The number of hours per day dependent on ventilation ranged from 6 to 24. Sixteen patients were ventilated continuously, and all of these children had a tracheostomy. The remainder required respiratory support only when asleep, i.e. overnight plus daytime rest periods in younger children. Hours of paid care vary from 0 to 168 hours per week, with invasively ventilated children and those with the most co-morbidities having greater levels of support. Of the current patients, 29 children, who are all having NIV, have no paid care at home and are solely managed by their parents.

Discussion

Our experience of providing LTV in a single, well-coordinated, geographically defined region of the UK demonstrates that, over the past 15 years, there has been a 30-fold increase in the prevalence of children receiving domiciliary long-term ventilation at home. Similar findings have been reported elsewhere in the UK and New Zealand [3, 15]. More children with neuromuscular disease are being offered domiciliary LTV in recognition of its technical feasibility and proven record in sustaining long-term respiratory function and reducing acute hospital admissions [9, 12]. The number of patients recognised to have CCHS has increased since the 1980s, due to increased awareness of the condition, the availability of a genetic test (PHOX2B), offered by the Bristol Molecular Genetics laboratory for the whole of the National Health Service, and recognition of the potentially excellent outcome for this group of patients [14]. As the number of children offered domiciliary LTV continues to rise, so will the corresponding impact on adult services. Most patients with DMD now survive into adulthood, and this number is expected to increase with improved management of respiratory failure and other complications in earlier life [2]. The trend towards non-invasive ventilation reflects increased screening with polysomnography and capnography in neuromuscular patients, greater confidence in this mode of ventilation, and technological advancements permitting its use in small infants.

The majority of LTV patients in our study had co-morbidities. It is likely that these data underestimate the true situation in our patient population, since data entry was not standardised. For example, obesity is frequently recorded in adolescents with DMD, with rates of over 50% [1], and yet, it was only recorded in two patients in this study. It might be anticipated that the frequency of wheelchair use will increase with time, as many patients are currently in infancy, and therefore their relative immobility does not yet warrant supplementary aids.

There are several important differences in our reporting compared with other studies. Firstly, the experience described relates to the case-mix of patients and model of care seen in the Bristol paediatric LTV service. No children in our study had chronic lung disease of prematurity, whereas other centres have reported an incidence of 3–5% [13, 15]. Additionally, Bristol has a national genetic reference laboratory and a long-standing interest in congenital central hypoventilation syndrome, which attracts a small number of children for management and diagnosis from outside the region. It is our current practice in CCHS to continue invasive ventilation until the age of 8–10 years and then, according to the child's wishes, switching to non-invasive ventilation. We have in one child delivered phrenic nerve stimulation delivered by implantable cervical bipolar electrodes during daytime hours, with standard respiratory support via tracheostomy continued overnight. Nearly all patients in our study remain on LTV until either death or transfer to adult services. In contrast, a higher rate of discontinuation of LTV has been reported in children, with up to 39% of patients able to wean from ventilation after a period of between 3 and 52 months in a New Zealand study [3]. However, there were differences in case-mix between this population and ours, with a higher proportion of airway and respiratory diagnoses in the New Zealand survey. Therefore, on the basis of our findings, we would expect a higher rate of discontinuation of LTV in this group of patients.

We describe patients on domiciliary ventilation whilst other authors have used a definition of LTV that captures any child on ventilation for longer than 3 months, which includes children in hospital who have not yet entered a domiciliary LTV programme [4, 5]. We chose this definition on the basis that knowledge of the number of children receiving domiciliary ventilation is important for planning of community resources, where the care burden is high but currently not systematically captured. This difference in reporting limits comparison with other studies, and it is likely that case-mix of patients and rates of discontinuation of LTV will differ between hospital and community-based populations. For example, a number of patients in our study were excluded due to weaning of their ventilation prior to discharge from hospital. This would particularly affect the apparent rate of LTV discontinuation.

There are some limitations to our study. Although we are confident that we have achieved high data capture of patients managed in Bristol, we are aware of a small number of patients on LTV in the South West region that are not managed by the Bristol paediatric LTV service. This would result in a small underestimation of incidence and prevalence. A national survey in September 2008 by the UK LTV group identified 69 children under 17 years in the South West region receiving LTV (E. Jardine, personal communication), although this included some patients not yet discharged from hospital. Concurrently, our database recorded 59 patients in the same age range, resident in the same postcodes and managed at home. This discrepancy will have the most impact on data from more recent years, following the appointment within the region of more paediatricians with a respiratory interest.

We do not have formal guidelines governing the commencement of LTV in a child, but our agreed approach has been not to offer invasive ventilation to children with diagnosed progressive neuromuscular conditions. In this group of children, we offer non-invasive ventilation as a bridge to palliative care. In recent years, the much wider array of detailed genetic and metabolic investigations has resulted in neurological conditions of uncertain aetiology being much more precisely diagnosed. However, many of these tests take many weeks or months to reach a conclusion, and the consequence of this is children may remain ventilated for prolonged periods of time on intensive care whilst a diagnosis is sought. Some of the patients have tracheostomies fashioned to facilitate ventilation, and in our experience, this makes later withdrawal of support more challenging.

In the UK, societal and parental expectations have changed as the use of home ventilation has become more widespread. This paper does not attempt to address the ethical issues surrounding the use of LTV in patients with life-limiting conditions. There is a significant financial cost to the wider health care community in supporting a relatively small number of LTV patients at home. More importantly, many clinicians have concerns that the “best interests” of the child are not always met through life-long tracheotomised ventilation. More research needs to be done on (a) the quality of life of the patient and (b) the burden to the family and siblings. Unfortunately, many of these decisions are currently decided in the law courts.

Conclusions

  • There has been a 30-fold increase in the number of children in the South West receiving long-term home ventilation over the past 15 years.

  • Children requiring LTV frequently have co-morbidities, many of which require specific additional interventions.

  • Very few patients discontinue LTV, and there are increasing numbers now transferring to adult services. Adult services will need to be developed to meet the needs of this population.