The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

An Evaluation of Delivered Oxygen Fractions in Four Self-Inflating Resuscitators

Timothy Cox, RRT1, John K. Rendle, RRT1, Wayne Manning, RRT1, Thomas Blackson, RRT2, James H. Hertzog MD1; 1A. I. duPont Hospital for Children, Wilmington, DE 2Christiana Care Health System, Newark, DE. 

Background: High delivered oxygen fractions are used during cardiopulmonary resuscitation. The fraction of oxygen delivered by self-inflating resuscitators may vary significantly under different conditions. The American Society for Testing and Materials (ASTM) Standard F-920 specifies a fractional delivered O2 concentration (FDO2) ³ 0.85 with an oxygen flow of 15 L/min and VE of 7.2 L (600 mL x 12/min) for adult units. However, different VE may be achieved during emergent conditions or with pediatric versus adult patients. We evaluated four currently available adult model self- inflating resuscitators to determine their FDO2 under varying conditions.

Methods:
4 disposable adult resuscitators with tube-type or bag reservoirs were evaluated: BLD Medical Pulmanex, Allegiance Airlife, Respironics Bag Easy and Nellcor IndGo. A bench model was developed using a fast-responding oxygen specific galvanic sensor (Ceramatec MAXO2) connected to a Michigan test lung. Lung compliance was set at 0.01 L/cm H2O. A fixed resistance, differential flow sensor was placed in line between the oxygen sensor and the self-inflating resuscitator to measure frequency, volume (VT), and peak end expiratory pressure (PEEP). Each resuscitator was manually operated at targeted volumes (VT) of 250 ml, 500 ml and 700 ml, at a frequency of 20 breaths/min, 0 PEEP, and a constant oxygen flow of 15 L/min. A frequency of 20 breaths was chosen based on the American Heart Association's pediatric recommendation for one-person rescue breathing. Ventilation was standardized via monitor feedback for 30 seconds followed by data collection every 3 seconds for a one-minute sampling period. 

RESULTS: 

Resuscitator Maximum Reservoir Volume Average VT (ml) Average PEEP (cm H2O) Average FDO2 (%)
Pulmanex Distal Bag (± 2000 cc) 240 3.50 96.47
512 6.00 88.42
695 7.30 85.13
Airlife 40'' Hose (± 375 cc) 308 3.25 100.00
537 5.65 94.34
716 7.95 83.13
Bag Easy Proximal Bag (± 850 cc) 275 3.30 100.00
516 5.44 100.00
707 7.55 99.81
IndGo 40'' Hose (± 700 cc) 272 3.00 100.00
503 5.60 100.00
695 7.20 95.28


CONCLUSION:
Adult self-inflating resuscitators may be used for emergent management of both pediatric and adult patients. We tested 4 commonly used adult resuscitators at a range of VT that might be used for these age groups during emergent conditions. In our model, FDO2 was maintained > 80% for all devices in all conditions, but variability between devices exists. Furthermore, significant levels of PEEP are generated under these conditions. Clinicians should be aware of the changes in these parameters when using self-inflating resuscitators at varying VE.

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