The Science Journal of the American Association for Respiratory Care

2002 OPEN FORUM Abstracts

VALIDATION OF A BREATH BY BREATH GAS EXCHANGE MONITOR UTILIZING A PROXIMAL AIRWAY FLOW SENSOR DURING MECHANICAL VENTILATION WITH CONTINUOUS BIAS FLOW.

Charles McArthur BA RRT RPFT, Immanuel- St.Josephs Hospital / Mayo Health System, Mankato, MN. Mary E Donlin RRT, Medical Graphics Corporation, St.Paul, MN.

BACKGROUND: This study was designed to evaluate the effect of continuous bias flow during mechanical ventilation on a breath by breath gas exchange monitor (CPXD, MEDICAL GRAPHICS, St.Paul, MN) with a proximal flow sensor.

Methods: A gas exchange validator, with a known VO2, VCO2, and VT was interfaced with a Puritan-Bennett 840 ventilator via a standard patient ventilator circuit. The CPXD sampled both gas concentrations and expired flow at the proximal end of the patient airway. The ventilator was set in the spontaneous mode to allow delivery of breaths as the validator demanded. Breath by breath measurements of VO2, VCO2, and VT were made at various bias flow settings (set on the ventilator) with the following validator settings: stroke volume 1049 ml, VO2 309 ml/min, VCO2 299 ml/min, frequency 10, duty cycle 0.5. Fifty breaths were collected at each bias flow setting.

Results: Measures of agreement (bias ± precision) between the validator and the CPXD gas exchange monitor are presented below:

Bias flow (L/M) VO2 (%bias ± 2SD) VCO2 (%bias ± 2SD) VT (%bias ± 2SD)
3 -4.85 ± .19 -4.29 ± 0.16 -3.05 ± 0.01
6 -4.21 ± 0.05 -3.30 ± 0.11 -2.67± 0.003
9 -4.53 ± 0.05 -3.30 ± 0.03 -2.67 ± 0.003
12 -4.21 ± 0.05 -3.63 ± 0.04 -2.67 ± 0.003
15 -4.53 ± 0.05 -3.63 ± 0.04 -2.57 ± 0.003
18 -4.85 ± 0.05 -3.63 ± 0.04 -2.48 ± 0.003

Conclusions: The CPXD gas exchange monitor with proximal airway flow measurement is not affected by continuous bias flow during mechanical ventilation.

Partially funded by Medical Graphics Corporation.

OF-02-149

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