2006 OPEN FORUM Abstracts
Comparison of Auto Peep Readings and Measurements on SIX Ventilators
Glenna
Muse RRT, Terry Glaubitz, CRT, Rachel
Myers RRT, Summer Thompson CRT, Doug Pursley, M.Ed., RRT Ozarks
Technical
Community
College
,
Springfield
,
MO
Background: Auto peep, also called intrinsic peep, in positive pressure ventilation is the
residual pressure left in the lung at the end of exhalation caused by air
trapping. Most ventilators produce an auto peep measurement but we were curious
as to how they compared to an external manometer reading.
Method: We tested a total of six ventilators:
the Viasys Avea, Drager Evita XL, Drager Evita 4, Maquet Servo i,
Puritan Bennett 840, Puritan Bennett 7200. On each ventilator we used the same
circuit, test lung, and manometer. The
ventilators were set up in pressure control mode with an inspiratory pressure of
25cmH2O, 0 set PEEP, and inspiratory time 1.5 seconds. Only the respiratory rate was varied in the
testing. Peep was read from each unit at
the same time it was manually measured with the Puritan manometer. Each set of
tests were performed a minimum of three times until the results were at least
duplicated, if not triplicated, for legitimacy.
Results: The ventilators ranked, in order of percent difference
from the manometer readings: Maquet
Servo I with a total percent difference from the manometer reading of 7%,
Drager Evita 4 of total percent difference of 9.3%, Drager
Evita XL total percent difference of 9.7%, Puritan
Bennett 840 total percent difference of 11.6%, Viasys
Avea with a total percent difference of 12.5%, and
Puritan Bennett 7200 with total percent difference of 13.6%.
| Ventilator | Rate | Total Peep-Vent | Total Peep-Mano | % Diff. | Ventilator | Rate | Total Peep-Vent | Total Peep-Mano | % Diff. |
| Viasys Avea | 30 | 15 | 17 | 12% | PB 7200 | 30 | 18 | 20 | 10% |
| 25 | 13 | 14 | 7% | 25 | 13 | 15 | 13% | ||
| 20 | 7 | 9 | 22% | 20 | 7 | 9 | 22% | ||
| Drager Evita XL | 30 | 18.8 | 21 | 10% | Drager Evita 4 | 30 | 18.9 | 21 | 10% |
| 25 | 14.4 | 15 | 4% | 25 | 14.1 | 15 | 6% | ||
| 20 | 7.7 | 9 | 14% | 20 | 8.7 | 10 | 13% | ||
| Servo i | 30 | 19 | 20 | 5% | |||||
| 25 | 13 | 14 | 7% | ||||||
| 20 | 8 | 9 | 11% | ||||||
| PB 840 | 30 | 18 | 20 | 10% | |||||
| 25 | 13 | 15 | 13% | ||||||
| 20 | 7.9 | 9 | 12% | ||||||
Conclusion: Comparing
the six ventilators using the analog manometer, the Maquet Servo i produced the
closest measurement of peep between its electronic interface and the mechanical
manometer with an average difference of only 1 cmH2O. The other five ventilators, showed slightly greater
but probably clinically insignificant differences between the manual and
electronic interface readings, producing disparities of no more than 2.2 cmH20
between the two readings.