Home Mechanical Ventilation in Sweden. Demography, Indications, Clinical Effects and Survival

Sammanfattning: Home mechanical ventilation in patients with chronic respiratory failure secondary to several different diseases has become widely acceptable as the provision of ventilatory support can provide symptomatic relief and increase life expectancy. Aims: To study the selection criteria underlying the initiation of home mechanical ventilation and to quantify the effects of in relation to blood gases and lung function; to examine temporal changes in treatment prevalence in Sweden; to study survival and causes of death and demonstrate possible related impact factors. Methods: Since January 1 1996 the nationwide Swedish Home Mechanical Ventilation Register prospectively has collected data on home ventilated patients. The studies founding this thesis are based on data from this register. In the neuromuscular patients (N=352) we examined symptoms, clinical signs and physiological findings that were motivating the initiation of treatment. We studied the clinical effects of home ventilation over time in patients with sufficient follow up data (N=288) regardless of the underlying diagnosis. We looked at the temporal changes and geographic inequalities in the prescription of home ventilation in Sweden. We examined survival data for a period of ten years in 1526 patients and in 337 deceased patients we studied the causes of death. Results: Daytime sleepiness was the most common clinical symptom motivating home mechanical ventilation in hypercapnic patients with neuromuscular diseases. The patients improved their daytime PO2 and PCO2 during spontaneous ventilation with approximately 1 kPa without a concomitant improvement in vital capacity after 6?24 months of treatment. We have found a medically justified continuing increase in the number of patients on HMV and an increasing proportion of Pickwickian patients. The evident dissimilarities in local prescription rates are not explained by different therapeutic criteria between the centres, but rather by differences in levels of ambition and/or problem recognition. The amyotrophic lateral sclerosis (ALS) group had by far the poorest survival rate. Survival was roughly in line with that in previous studies and predictors of increased risk for death in non-ALS patients were greater age, concomitant oxygen treatment, tracheostomy ventilation and launch of HMV in an emergent clinical setting. Acute start of ventilation and the use of concomitant oxygen were more frequent in small centres. In an eight-year period 1996 -2003 the cause of death was respiratory in 55% and cardiovascular in 31%. In the different patient categories there were apparent deviances from this pattern. We found more cardiovascular causes compared to previous reports and cardiac insufficiency may be underestimated as a terminal complication in home ventilation. This applies to the Pickwickian patients in particular. Conclusions: In hypercapnic patients daytime sleepiness may be an important motive for starting HMV. Blood gases during spontaneous ventilation improve after start of treatment. The numbers of patients on home ventilation continue to increase (especially Pickwickian patients) and there are evident inequalities in local prescription rates in Sweden. ALS patients show by far the poorest survival, in the non-ALS patients a number of patient related factors affected survival. The hazard for cardiovascular death appears to be more significant than previously reported especially in the Pickwickian patients.