Underventilation with a Small Adult Bag (1,000 ml): Persistent Gaps Despite Real-Time Flow-Guided Training
Abstract Body: Introduction/Background Manual ventilation is a critical, yet variable skill in prehospital and hospital care. Concerns of over-ventilation (tidal volume, rate, etc.) during bag-valve-mask (BVM) ventilation have led many EMS systems to adopt smaller resuscitator bags, with the risk of underventilation.
Research Question/Hypothesis Can a small adult bag provide adequate ventilation for an average adult male, and can performance be improved after a brief educational intervention using software to measure flow and tidal volume, along with a flow limiting device to encourage more aggressive bag compression to achieve adequate tidal volume, while preventing over-ventilation by mechanically limiting inspiratory flow.
Methods/Approach 55 first responders from Johnson County, KS participated in a pre/post study. Participants were instructed to provide 60 seconds of manual ventilation to a simulated healthy adult male (target Vt: 420-570 ml) using their standard small adult bag (VENTLAB AirFlow 1000 mL). Tidal volume (Vt), peak flow rate, and respiratory rate (RR) were recorded (SotairIQ training platform; SafeBVM, Boston). Afterward, providers completed a 2-minute training video and 1-minute hands-on flow training with a valve which stops inspiratory flow if it exceeds 55 LPM (Sotair, SafeBVM, Boston) and SotairIQ. They then repeated the same task using the same bag with the Sotair inline.
Results/Data Mean peak flow rates and Vt were higher after training (44.5+5.2 vs 28.3+12 LPM; p<0.05; 418+38.6 vs 323.2+92.2 ml; p<0.05). Before training, 87.8% of breaths were <420 mL compared to 51.5% post-training (p<0.05). Baseline respiratory rate was 9.73+2.49, compared to 11.8+4.36 after training; p<0.05. Estimated alveolar ventilation (assuming a dead space of 150 ml) increased from 1776.7 to 3409.7 ml/minute after training (p<.0.05).
Conclusion(s) The small adult bag (1,000 ml) leads to smaller tidal volumes than recommended for an average adult male; and (2) although the training tool (+ flow-limiting device) led to a near doubling in estimated alveolar ventilation, many breaths were still suboptimal after training. These results provide further evidence for the inadequacy of small bags in ventilating adults, but suggest that training and the use of a flow-limiting device may improve the quality of ventilation when a small bag is used..
Joles, Kevin
( Olathe Fire Department
, Olathe
, Kansas
, United States
)
Author Disclosures:
Kevin Joles:DO NOT have relevant financial relationships