2012 OPEN FORUM Abstracts
FRACTION OF INSPIRED OXYGEN DURING INADVERTANT LOW FLOW BAG MASK VENTILATION.
Sara K. Green1, William M. LeTourneau2; 1St Paul College, St Paul, MN; 2Fairview Southdale Hospital, Edina, MN
Background: During bag mask ventilation (BMV) there is no standardized recommendation for liter flow delivery. Current ACLS guidelines simply advise supplemental oxygen delivery of 100%. Clinical conditions vary greatly with the possibility of inadvertent low flow meter settings to manufacture recommendations of 15 L/m and an arbitrary flush setting. The purpose of this study is to determine delivered FiO2 during low flow BMV with the variables of liter flow (L/m), delivered tidal volume (Vt) and ventilation rate (BPM). Method: Data was obtained using three different adult manual resuscitators (BMV #1 with reservoir tubing, BMV #2 with a reservoir bag and BMV #3 with a variable volume reservoir tubing) while measuring delivered FiO2 using an oxygen analyzer. Analysis was done at flow meter settings of 2 L/m and 4 L/m. At each flow rate three ventilation rates were assessed (6 BPM-consistent with a 30:2 ventilation to compression ratio, 10 BPM and 20 BPM), and finally, three different tidal volumes were assessed at each ventilation rate (500mL, 800mL, and 1000mL). All testing was done for 2 minutes and 30 second intervals to obtain a steady state FiO2 and tidal volumes were applied using a hinged arm and three level stop block device. Results: At a flow rate of 2 L/m all devices demonstrated thier highest FiO2 at 6 BPM and a Vt of 500 mL (58.4%, 60.8% and 56.7% respectivley), while all had progressive drops in FiO2 as ventilation rate and Vt increased, demonstrating thier lowest FiO2 of 30.6%, 29.8% and 28.1% respectively at a ventilation rate of 20 BPM and a Vt of 1000 mL. At a flow of 4 L/m BMV #1 showed a highest FiO2 at 10 BPM and a Vt of 500 mL (75.7%), while BMV #2 and BMV #3 showed a highest FiO2 at 6 BPM and a Vt of 500 mL (71.4% and 69.3% respectivley). Dispite these variations at the 4 LPM level there was also a progressive drop in FiO2 as ventilation rate and Vt increased, demonstrating thier lowest levels of 40.6%, 35.7% and 36.4% respectively at a ventilation rate of 20 BPM and a Vt of 1000 mL (Table 1). Conclusion: All three adult manual resuscitators demonstrated that at an inadvertent low flow rate of 2 L/m or 4 L/m there is superior FiO2 delivery at lower ventilation rates and lower tidal volumes. The results of this study support current recommendations of ventilating with lower tidal volumes and avoidance of hyperventilation during resuscitation. Sponsored Research - None