Changing prevalence of chronically ventilator-assisted individuals in Minnesota: Increases, characteristics, and the use of noninvasive ventilation

BACKGROUND: The prevalence and characteristics of chronically ventilator-assisted individuals (VAI) in the United States are largely unknown. There have been recent changes in the sites and methods of caring for VAIs, as exemplified in the increase in dedicated VAI hospitals and the use of noninvasive positive pressure ventilation (NPPV). To determine the changing prevalence and characteristics of VAIs in Minnesota, we conducted a cross-sectional survey of all VAIs in Minnesota in 1986, 1992, and 1997. METHODS: All providers of care for VAIs responded to similar questionnaires about each VAI in each survey year. Information obtained about VAIs included: age, respiratory diagnosis(es), location, duration of assistance, and need for full or partial support. The 1997 survey included a determination of patients receiving NPPV with a backup rate. RESULTS: At a time when state population increased from 4.26 million (1986) to 4.47 million (1992, +4.9%) to 4.69 million (1997, +5.1%), the number of VAIs in Minnesota increased from 103 VAIs in 1986 to 216 in 1992 (+110%) to 306 in 1997 (+42%). The predominant reason for requiring assistance was ventilatory muscle dysfunction from polio, muscular dystrophy, cervical trauma, or amyotrophic lateral sclerosis (ALS). The most prevalent age groups are <11 and >70 years old. Polio, chronic obstructive pulmonary disease (COPD) and ALS VAIs were older, while those with muscular dystrophy and cervical trauma were younger. There was a bimodal distribution of VAIs in duration of ventilation: those with obstructive and restrictive lung diseases were assisted shorter periods, while the long-term patients (ventilated for >5 years) were those with ventilatory muscle dysfunction. Noninvasive ventilation accounted for 47% of the increase in VAIs between 1992 and 1997. CONCLUSIONS: The number of VAIs in Minnesota continues to increase at a relatively constant rate (≃18/yr), driven by equivalent rises in the number of noninvasive and intubated patients. Ventilatory muscle dysfunction is the predominant disability requiring long-term assistance, while the obstructive-restrictive disease VAIs had a shorter duration of ventilatory assistance.