The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

Comparison of Static Compliance on Six Ventilators

Chris Davies, RRT, Mechelle Wilson, RRT, Keith Matlock, CRT, Jana Maciejczak, CRT, Doug Pursley M.Ed. RRT                                      

Ozarks Technical Community College, Springfield, MO

Introduction: The purpose of this study was to test the accuracy of static compliance (Cstat) measurements compared to a control value from a Michigan Test Lung. The ventilators tested for Cstat accuracy were the Maquet Servo i, Drager Evita XL, Drager E4, Viasys Avea, Puritan Bennett 840, and the Puritan Bennett 7200.

Methods: We compared Cstat by connecting the different types of ventilators with the same ventilator circuit and no humidifier to the Michigan Test Lung Model 560li. The Michigan Test Lung was set to compliance values of 10, 50, 80, and 100 cmH2O. Volume controlled ventilation with a set tidal volume of 600ml, f 12 breaths per minute, and flow rate of 45 l/m was set on each ventilator.

Results: With zero PEEP, the ventilators ranked in the following order from most accurate to least accurate (overall average percent differences from the control value are in parenthesis): PB 7200 (1.25%), Maquet Servo i (4.2%), Viasys Avea (4.6%), PB 840 (10%), Drager E4 (22.5%), and Drager XL (26.7%). When five cmH2O PEEP was applied to the circuit, the ranking from most accurate to least accurate was: Viasys Avea (5%), Maquet Servo i (7.1%), PB 7200 (11.25%), PB 840 (16.25%), Drager E4 (25.4%), and Drager XL (29.6%).

TABLE 1.

PB 7200 Set Cstat Meas. Cstat % Diff. between set and meas. Plat Set PEEP PB 840 Set Cstat Meas. Cstat % Diff. between set and meas. Plat Set PEEP
  100 100 0 6 0   100 111 11 6 0
  100 115 15 10 5   100 117 17 10 5
  80 79 1 8 0   80 88 10 8 0
  80 87 9 12 5   80 93 16 12 5
  50 49 2 13 0   50 54 10 12 0
  50 54 8 16 5   50 58 16 16  
  10 11 10 56 0   10 11 10 56 0
  10 11 10 59 5   10 11 10 58 5
Avea Set Cstat Meas. Cstat % Diff. between set and meas. Plat Set PEEP Drager XL Set Cstat Meas. Cstat % Diff. between set and meas. Plat Set PEEP
  100 96 4 6 0   100 123 23 6 0
  100 97 3 11 5   100 130 30 11 5
  80 83 4 7 0   80 104 30 7 0
  80 84 5 12 5   80 99 24 13 5
  50 53 6 12 0   50 65 30 12 0
  50 53 6 16 5   50 70 40 16 5
  10 11 10 49 0   10 12 20 54 0
  10 12 20 51 5   10 12 20 53 5
Servoi Set Cstat Meas. Cstat % Diff. between set and meas. Plat Set PEEP Drager E4 Set Cstat Meas. Cstat % Diff. between set and meas. Plat Set PEEP
  100 98 2 6 0   100 121 21 6 0
  100 107 7 11 5   100 128 28 10 5
  80 76 5 8 0   80 97 21 7 0
  80 84 5 13 5   80 98 23 12 5
  50 48 4 13 0   50 64 28 12 0
  50 54 8 17 5   50 62 24 16 5
  10 12 20 55 0   10 12 20 52 0
  10 12 20 56 5   10 13 30 55 5

Conclusion: In this bench test we found that when compared to the set compliance from the Michigan Test Lung, all six of the ventilators gave more accurate measurements with zero set PEEP and were less accurate when 5 cmH2O PEEP was added to the ventilator circuit. Plateau pressures were remarkably consistent across most of the spectrum of compliance between the six ventilators. The Viasys Avea gave the narrowest range of error between zero PEEP and five cmH2O PEEP.         

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