The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

Variation of Fractional Delivered Oxygen Concentration (FDO2) during Spontaneous Breathing from a Manual Resuscitator:  A Bench Study

Anthony J. Asciutto RRT,  Robert S. Slonac RRT, Michael K. Howard MBA RRT, John D. Davies RRT FAARC, Michael A. Gentile RRT FAARC, Robert B. Campbell MBA RRT, Neil MacIntyre MD FAARC Duke University Medical Center, Durham, NC.

Background: Manual resuscitators are primarily used in clinical situations such as emergency resuscitation, moderate sedation, endotracheal intubation, and patient transport to provide ventilation and support oxygenation. At times, our clinical practice may allow a spontaneously breathing patient to breathe unassisted from a manual resuscitator. We hypothesize that a patient would receive a FDO2 of 1.0 when breathing spontaneously from a manual resuscitator.

Methods:
A bench study was conducted to test the hypothesis. A double-chambered test lung (Vent Aid TTL, Michigan Instruments, Inc. Grand Rapids, MI) with a crossover latch was used in concert with a Puritan Bennett 840 ventilator (Nellcor Puritan BennettT Inc., Carlsbad, CA). The ventilator was connected to the right chamber in order to drive the left chamber into a spontaneous inspiration. An oxygen monitor (Maxtec Oxygen Monitor, Maxtec, Inc. Salt Lake City, UT) connected to the left chamber was used to analyze the FDO2 from the manual resuscitator used by  our institution  (AirFlow Small Adult Resuscitator, AF 5100 Series, Ventlab Corp., Mocksville, NC). Ventilator tidal volumes of 400, 480, and 560 mL and inspiratory flow rates of 40, 60, 80 and 100 L/m were used to simulate different spontaneous breathing patterns. Data were collected for each tidal volume and inspiratory flow combination at three oxygen flow rates (5, 10, 15 L/m) provided to the resuscitator.

Results:   The FDO2 data points are presented in the table below. 

  40 L/m 60 L/m 80 L/m 100 L/m 40 L/m 60 L/m 80 L/m 100 L/m 40 L/m 60 L/m 80 L/m 100 L/m
  5 L 5 L 5 L 5 L 10 L 10 L 10 L 10 L 15 L 15 L 15 L 15 L
VT 400 76.5 82.5 88.2 91 74 73.3 77.8 80.5 87.5 84.2 83.2 87.6
VT 480 74 79.5 84 88 71.3 70.6 75.1 78.5 87.9 81.1 81.2 84
VT 560 70 77 82.4 85.6 71.1 69.4 74 77.1 85.4 78 79.1 82.4

Conclusion: In this bench study, the FDO2 measurements from a manual resuscitator during simulated spontaneous breathing, without manual assistance, demonstrated an unexpected degree of variability with a range from 69.4 to 91%. A FDO2 of 1.0 was not delivered under the testing conditions.

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