Evita Model Set 01.zip __HOT__
Design: Five study conditions on a lung model (CPAP at 0, 5, and 10 mbar, CPAP 5 mbar plus pressure support 2 mbar with both EVITA models, and CPAP 5 mbar with decreasing levels of flow and pressure trigger sensitivity with the SV 300) and three randomized study conditions in nine patients recovering from open heart surgery (condition A: EVITA-2, CPAP 5 mbar; condition B: SV 300, CPAP 5 mbar, flow trigger; condition C: SV 300, pressure trigger-4 mbar).
Evita Model Set 01.zip
Measurements and results: At each study condition we measured WOB, pressure-time product (PTP), WOB and PTP imposed (WOBimposed and PTPimposed), tidal volume, minute ventilation, respiratory rate, inspiratory trigger time, trigger pressure, trigger PTP, duration of inspiration, mean and peak inspiratory flow, and the delay from the onset of inspiration to peak inspiratory flow. Since the SV 300 automatically generates an additional pressure support of 2 cm H2O PTP, WOB, WOBimposed, and PTPimposed were higher with the EVITA-2 and EVITA-4 regardless of the trigger sensitivity set on the SV 300. The difference was neutralized with both types of EVITA ventilator by adding 2 mbar of pressure support during CPAP in order to achieve comparable conditions. Inspiratory flow response was faster with both EVITA models, expiratory flow resistance was higher with the SV 300. Decrements of trigger sensitivity with the SV 300 accelerated the flow response.
Differences between hospitals and models of mechanical ventilator were assessed by two-way analyses of variance (ANOVA; SigmaStat; Systat Software Inc., San Jose, CA, USA) considering the absolute value of the discrepancy between the figure set on the ventilator and the delivered values actually measured in the test lung. Similarly, the values of the parameters read at the ventilator panel were compared to the actual values measured by the test lung. To this purpose, we decided to average the readings provided by the ventilator during the trial. As it is not always clearly reported if a given ventilator is reporting independent values for each single breath or after filtering or smoothing procedures, considering an average reading over the recording period minimizes possible differences due to the data-processing strategy adopted by each model of ventilator.
The same variables are represented in Figure 3 grouped by ventilator model. In this case, the results are quite variable, with the variability within the same model being, for most variables, bigger that the variability between models.
Notes: Labels identify the following ventilator models: EVITA4: Draeger Evita 4 (25 machines); SERVOI: Siemens/Maquet Servo I (16 machines); SVC900C: Siemens SV900C (12 machines); SERVO300: Siemens/Maquet Servo 300 (7 machines); EVITAXL: Draeger Evita XL (3 machines); SV900D: Siemens SV900D (1 machine); EVITA2: Draeger Evita 2 (1 machine) and ENGSTROM: GE Engstrom (1 machine).
This is confirmed by the absence of statistically significant differences in the discrepancies between the preset and actual values between hospitals. Considering the different ventilator models, the two-way ANOVA analysis showed a significant difference in the errors between the ventilator models only for PEEP (P = 0.009) and RR (P
As it is not unusual that old machines are present in small number of units in an ICU, we kept the composition of the set of devices in use in the ward, therefore including also ventilators that were present as only one or two units, as this is what a patient admitted to that unit will receive. As a consequence, several ventilator models were represented by only small numbers, making it impossible to apply statistical analysis on performances of these units.
Manufactured in Lübeck, Germany for over 25 years, the Drager Evita is a compact, highly efficient ventilator system. The device can be identified by the large digital monitor displaying patient readings with a large knob in the bottom right corner, its central unit with a translucent blue covering, and its four wheels on the bottom of the unit for mobility. The model number and device name are featured prominently on a plaque on the front of the unit.