A headline from The Times newspaper of 14 August 2000¹—“Power cut kills man on home ventilator”—is likely to strike a chill in the heart of anyone involved in providing home respiratory care. Bearing in mind it is impossible to guarantee complete safety even in the hospital environment, what is the respiratory practitioner’s responsibility towards the individual receiving ventilatory support in the home, and how can these risks be minimised?

EXTENT OF THE PROBLEM

The recent Eurovent study² showed that there are around 21 500 individuals receiving home ventilation in Europe: about one third have neuromuscular conditions, one third parenchymal lung disease (mainly COPD), and the remainder have chest wall disorders (scoliosis, thoracoplasty, obesity hypoventilation syndrome); 13% use tracheostomy ventilation and around 10% are in the paediatric age range. Although the prevalence of home ventilation varies considerably, in nearly all regions there is a rapid growth in those receiving home non-invasive ventilation (NIV).

One of the difficulties in assessing the extent of ventilator related complications in the home/community is that in most countries there is no centralised database, and even where equipment failure is recorded the consequences of the malfunction for the patient are not clear. Further information on quality control of ventilator care in the home from the Eurovent survey has shown that only 56% of hospitals initiating home ventilation assessed whether patients or caregivers cleaned and operated the ventilatory equipment correctly after discharge from hospital, and even fewer centres (25%) were aware of a vigilance system for reporting adverse events or mechanical failure. Ventilator servicing was carried out by external equipment companies in many countries, but in general there was wide variation in provision.^2,3 In some countries such as France and Denmark home care is comprehensive and well organised⁴ while, in others, funding for the home equipment is problematical, let alone continuing support in the community.

In a US study Srinivasan et al⁵ surveyed the frequency, causes, and outcome of home ventilator failure over 1 year in 150 adult and paediatric ventilator assisted individuals of whom 76% received ventilation via a tracheostomy. The majority had neuromuscular disease including 34% with quadriplegia, and 46% required 24 hour ventilatory support. 189 cases of suspected ventilator failure were reported per 840 000 hours of assisted ventilation (or one failure for every 1.25 years of continuous ventilator use). Notably, the more vulnerable 24 hour ventilator dependent patients were more likely to experience problems (66% of incidents), but when this figure was adjusted for hours of use the rate was similar to those using part time ventilation. Episodes of failure occurred in 28% of those receiving night time and part daytime ventilation, and in only 6% in those requiring support solely during sleep. Mechanical failure or defective equipment was present in 73 of the 189 incidents (39%). Improper care, damage, or misuse by caregivers was felt to be responsible in 13%, no problem could be identified in 16%, and in a proportion the equipment was functioning but a change in the patient’s condition had been misinterpreted as ventilator malfunction. It is important to note that maladjustment of settings and improper use were not thought to be malicious but due to problems with caregiver education. Immediate correction of the problem was achieved by replacing the ventilator in 44%, repairing a malfunctioning part in 6%, and adjusting ventilator settings in 21%. Crucially, only two patients required admission to hospital and no deaths or serious injury resulted. Of particular relevance is the fact that home support in these patients was provided by a branch of the National Medical Homecare system and many patients had professional caregivers; also all individuals who were 24 hour ventilator dependent or lived more than 1 hour from the respiratory homecare company were given a second back-up ventilator in the home. No detail was given of the types of ventilator used or the nature of mechanical faults.

In this issue of Thorax Farré et al⁶ have examined the performance of home ventilators in a quality control study of 300 patients in Barcelona. A much smaller proportion of these patients required tracheostomy ventilation (4.3%) or were 24 hour dependent (1.3%) than in the US study, but this is probably representative of current proportions in Europe. The majority had chest wall or neuromuscular disease and received nocturnal non-invasive ventilation. Home mechanical ventilation was initiated in several hospitals and domiciliary ventilator care provided by four different homecare companies. The authors examined whether the ventilator settings in the home matched those prescribed at hospital set-up, the performance of the ventilator in delivering the preset volume and pressure, and tested the function of the ventilator alarms. They found a mismatch between prescribed and actual delivered pressure or volume of approximately 10%. Alarms for power failure and circuit obstruction (high pressure) failed in 0.9% and 5.1% of ventilators respectively but, disconcertingly, disconnection alarms did not work in 52 (18.6%). Clearly, failure of disconnection alarms is likely to be more serious in patients with very little breathing autonomy, and may also have adverse consequences during sleep. However, the authors found no link between ventilator performance or alarm problems and the number of hospital admissions in the year before the study. Ventilator compliance and subjective factors such as tolerance, interface issues, side effects, and quality of life which might affect ventilator use were not assessed.

RISK MANAGEMENT

At first sight the results of the study by Farré et al⁶ highlight discrepancies in settings and alarms but are relatively reassuring in that there were apparently few significant adverse consequences for patients. However, from a comprehensive risk management perspective, this misses the point. Ventilators can break down but mechanical failure is infrequent and predictable. Ventilator users, carers, and their interaction with the ventilator, on the other hand, are not. Herein lies the problem—a key part of any home care programme should be education of patients, families, and carers to help them use the equipment confidently and safely and to have a sensible plan of action once a problem arises.

Good communication and a structured discharge plan adapted to the individual are required. The patient and/or carers should complete competency training on how to operate the equipment, identify simple problems, and when to seek advice. Educational materials are now widely available. Arrangements are necessarily more complex in patients who are dependent on tracheostomy ventilation. Here there are additional risks associated with the tracheostomy which can become blocked, displaced or fall out, and because those receiving ventilation via a tracheostomy often have little or no spontaneous breathing capacity. Tracheostomy care and safe suctioning, as well as ventilator operation, need to be taught before discharge. Deterioration in respiratory function and increased ventilator dependency is inevitable in patients with motor neurone disease/amyotrophic lateral sclerosis (MND/ALS) and will occur over a slower period in conditions such as Duchenne muscular dystrophy. Safety considerations need to evolve with the course of the underlying disease.⁷ The potential problems and solutions are shown in table 1.

Ventilator users need telephone access to a team member, hospital ward, or service that they can contact at all times. Frequent callouts are an indication for medical review to assess disease state and appropriateness of ventilator settings, in addition to a check on ventilator performance. Helping patients and carers to recognise medical problems such as early signs of a chest infection will allow them to seek prompt medical review or to start a reserve course of antibiotics, escalate bronchodilator treatment, etc. Home surveillance using videophone monitoring of highly ventilator dependent patients and modem transmission of oximetry has been reported^8,9 but use of these high technology approaches is not widespread. A limited number of patients—including some 24 hour ventilator dependent children—benefit from detailed evaluation of ventilation with Sao₂ and CO₂ home monitors, but highly unstable patients are not suitable for home care and nocturnal NIV users do not need this level of supervision. Clearly, detailed home monitoring is pointless if it does not inform or enhance care. Conveniently, newer ventilators now provide increasing amounts of information that can be downloaded by smart card. These may identify problems such as leaking, insufficient inspiratory pressure, or an inappropriate back-up rate which can be easily remedied. Further developments in this field are likely.

So, who is liable if problems occur in the home? If a hospital has provided the ventilator and set the patient up on it, then that hospital’s responsibility is likely to extend indefinitely unless this has clearly been delegated (to a home care company or another clinician). Transfer of follow up of mechanical issues to a GP or local team with no experience in ventilatory support is inappropriate. The concept of medical negligence applies to home ventilation in the same way that it applies to practices in hospital. The healthcare team should be expected to identify risks which are reasonably foreseeable (table 1) and to take action to remedy these as far as possible. However, the law does recognise that some events are either not foreseeable or beyond the bounds of reasonably practical preventative measures.¹⁰ Each case is decided on the individual circumstances in the light of expert opinion. Where guidelines and protocols are available—for example, manufacturers’ recommendations for ventilator servicing—they should be followed unless there are specific reasons to the contrary, which should be noted.¹⁰

Farré et al are correct in concluding that attention to detail in setting up and servicing of ventilatory equipment in the home is essential. Similar attention directed towards education and competency training of patients, carers, and families and continuing support in the home are just as important. Patient shared records should facilitate the exchange of key information such as the ventilator type, settings, interfaces, tracheostomy size, usual blood gas measurements, and advance directives with all members of the care team.

Finally, it is usually advisable to explain carefully to the patient and family the risks associated with home ventilation and the steps taken to minimise (but necessarily not totally abolish) them. With sensible arrangements in place, most willingly accept this trade off as home care, where possible, is far preferable to long term hospital care.