| Abstract | OBJECTIVE: To test a method that allows automatic set-up of the ventilator controls at the onset of
ventilation. DESIGN: Prospective randomized crossover study. SETTING: ICUs in one adult and one
children's hospital in Switzerland. PATIENTS: Thirty intubated stable, critically ill patients (20 adults and
10 children). INTERVENTIONS: The patients were ventilated during two 20-min periods using a
modified Hamilton AMADEUS ventilator. During the control period the ventilator settings were chosen
immediately prior to the study. During the other period individual settings were automatically determined by
the ventilatior (AutoInit). MEASUREMENTS AND RESULTS: Pressure, flow, and instantaneous
CO2 concentration were measured at the airway opening. From these measurements, series dead space
(V(DS)), expiratory time constant (RC), tidal volume (VT, total respiratory frequency (f(tot), minute
ventilation (MV), and maximal and mean airway pressure (Paw, max and Paw, mean) were calculated.
Arterial blood gases were analyzed at the end of each period. Paw, max was significantly less with the
AutoInit ventilator settings while f(tot) was significantly greater (P < 0.05). The other values were not
statistically significant. CONCLUSIONS: The AutoInit ventilator settings, which were automatically
derived, were acceptable for all patients for a period of 20 min and were not found to be inferior to the
control ventilator settings. This makes the AutoInit method potentially useful as an automatic start-up
procedure for mechanical ventilation. |