The Science Journal of the American Association for Respiratory Care

2004 OPEN FORUM Abstracts

Accuracy of Monitoring During Non-invasive Positive Pressure Ventilation (NPPV): A Comparison of the Respironics® BiPAP® Vision™ Ventilatory Support System and the Draeger Savina® ventilator.

Bruce DeLawyer, BS, RRT, Randall Evaro, RRT, Ben Biermann, RRT, Paula Goodsell, RRT, Jacquie Hedrich, RRT, Bruce Meyer, RRT, Dave Shuldes, BS, RRT, James Souza, MD St. Luke’s Regional Medical Center, Boise, Idaho, Dennis Bing, RRT, Draeger Medical, Inc.

Background: Many hospitals currently apply NPPV for treatment of patients in Acute Respiratory Failure (ARF), using devices with less monitoring capability than ventilators used for intubated patients. Due to continuous gas flow delivery and single circuit design, delivery of volumes for ventilation is extrapolated, not directly measured, and simulated changes in respiratory condition to model patients in ARF have demonstrated inadequate volume delivery.1 FiO2 monitoring is not integrated, and may vary from set values.2 We compared NPPV monitoring performance of two devices used at St. Luke’s Regional Medical Center (SLRMC) for NPPV: the Respironics® BiPAP® Vision™ (Vision) and the Draeger Savina
® (Savina) ventilator Non- Invasive Ventilation (NIV) option in Pressure Support (PS) mode.

Methods: We randomly selected 20 adult patients with ARF who received NPPV via face mask with the Vision for at least three hours and placed them on NIV- PS mode with the Savina at the same inspiratory and expiratory pressure settings and used the Vital Signs, Inc. Limb-O™ single-limbed circuit with the Savina. We recorded set and delivered FiO2, inspiratory and expiratory pressures (PAW), device- reported Tidal Volume (VT), patients’ spontaneous respiratory rate (RR-P), ventilator delivered respiratory rate (RR-V), heart rate (HR), pulse oximetry (SpO2) just prior to, and within 60 minutes following the change. Data were analyzed for correlation, regression, and ANOVA using the Microsoft® Excel 2002 Data Analysis ToolPack™.

Results: We found no significant change in HR or SpO2, but found significant differences in accuracy of FiO2 delivery, VT delivery, and response to patient’s breathing, (RR-P) – (RR-V).

FiO2 set- FiO2 measured Vision Savina
mean ± 2sd 0.069 ± 0.09 0.003 ± 0.01
correlation –r2 0.96526 0.99945
  p < 0.001
Reported VT Vision Savina
mean ± 2sd 619 ± 420 377 ± 348
mean % difference ± 2sd 39.33 % ± 31.92 %
  p < 0.001
(RR-P) –(RR-V) Vision Savina
mean ± 2sd 1.75 ± 1.80 0.05 ± 0.22
correlation –r2 0.89816 0.99763
  p < 0.001

Conclusions: Delivered FiO2 by the Vision was less than set, by as much as 0.18. VT reported by the Vision was as much as 424 mL higher than the exhaled volume directly measured by the Savina at the same PAW. These data raise our concern that monitoring with devices not designed for use with intubated patients may not provide adequate information to assure appropriate ventilation and oxygenation for patients with a deteriorating pulmonary condition. The Savina data provides a more accurate basis for clinician decisions. As an outcome of this study, we now require the precision provided by the Savina for NPPV of patients with ARF at SLRMC.

1 Adams A, Bliss P, Hotchkiss J. Effects of Respiratory Impedance on the Performance of Bi- Level Pressure Ventilators. Resp Care 2000; 45 (4): 390-400.

2 Respironics® BiPAP® Vision™ Clinical Manual, Section 13-3.

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