Objective: During home mechanical ventilation the prescribed settings are applied without permanent supervision of health professionals. After a long-time period of unattended operation at home the ventilator may not apply the ventilation parameters prescribed. This quality control study of home mechanical ventilation assessed whether tidal volume (V(T)), frequency (f), and minute ventilation (V'(E)) actually applied by the ventilator coincide with the values set on the ventilator control panel and with those prescribed.
Measurements: Actual V(T), f, and V'(E) applied by the ventilator in 30 patients on nocturnal HMV were measured at the patients' homes. The patients were subjected to volume targeted assist ventilation through nasal mask (n=28) or tracheostomy (n=2). The values of V(T), f, and V'(E) set at the ventilator were recorded. The actual and set V(T), f, and V'(E) values were compared with those prescribed.
Results: Considerable differences were found between actual, set and prescribed V(T), f, and V'(E). Actual V'(E) was significantly lower than V'(E) set: mean difference was 0.82 l/min, with considerable individual differences. Differences between actual and prescribed V'(E) were caused both by a poor performance of the ventilator and by a discrepancy between the values prescribed and those set at the ventilator control panel.
Conclusions: Regularly assessing the actual performance of ventilators at the patient's home is a quality control procedure useful for detecting malfunctions which could improve compliance and outcome of home mechanical ventilation.