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Over the last three decades, home mechanical ventilation (HMV) has become a widely accepted treatment option for patients with chronic hypercapnic respiratory failure that arises from different etiologies such as chronic obstructive pulmonary disease (COPD), restrictive thoracic disorders, neuromuscular disorders, and obesity hypoventilation syndrome.1,2 There is increasing evidence that HMV is capable of improving symptoms, health-related quality of life (HRQL), and long-term survival in most of these patients,1–3 although the impact of HMV on survival in patients with COPD is still a matter of debate.4,5 Thus, HMV should be considered in every patient presenting with symptomatic chronic hypercapnic respiratory failure.
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In principle, HMV can be delivered by the application of long-term invasive mechanical ventilation, which requires the insertion of a tracheal tube following tracheostomy. Alternatively, noninvasive ventilation can be used to implement HMV via two possible routes. First, by application of negative pressure ventilation, which achieved international renown in the days when iron-lung ventilation was the preferred method for treating poliomyelitis; nowadays, this technique is seldom used.2 Second, noninvasive positive-pressure ventilation (NPPV) can be delivered by connecting the natural airways of a patient and the artificial airways of the ventilator system by the use of face masks, which cover either the nose alone (nasal masks) or both the mouth and nose (oronasal masks).6 Mouthpiece ventilation is an additional option, particularly for neuromuscular patients.7
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According to a large European epidemiologic study covering more than 21,000 HMV patients from sixteen different countries (Eurovent survey), the overall prevalence of HMV reportedly was 6.6 per 100,000 inhabitants.8 Substantial variation, however, has been identified among countries in terms of (a) prevalence, (b) the relative proportions of specific patient groups receiving HMV, and (c) HMV techniques. Nevertheless, the number of HMV patients is steadily increasing,9 and the Eurovent survey only refers to the time span of 2001 to 2002.8 Moreover, the survey was confined to selected HMV centers that were invited to participate, whereas HMV is increasingly being implemented by many hospitals that are not officially known as HMV centers. Thus, the prevalence of HMV varies substantially between different countries and is at present much higher, at least in some Western countries, than what was estimated by the Eurovent study. Of similar importance is the fact that the pattern of different conditions underlying chronic respiratory failure is changing over time, with patients suffering from COPD and obesity hypoventilation syndrome experiencing the largest increase in prevalence.9
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The Eurovent study also identified 13% of the survey population as recipients of invasive ventilation, with the highest percentage comprising patients with neuromuscular disorders (24%). Most patients received NPPV and only 0.005% received other forms unlike positive-pressure ventilation. Thus, NPPV has become the predominant means of delivering HMV.
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The Respiratory System
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The respiratory system consists of two independent parts, each of which can be selectively ...