Abstract
Purpose
We conducted this study to evaluate the effects of fatigue, impedance (resistance and compliance), and use of 2 hands on the volumes delivered during manual bag-valve ventilation.
Methods & Materials
Ventilation was de-livered to a Michigan Instruments Test Lung. An adult Laerdal resuscitator with gas collection head was used with a Bear VM-90 to measure tidal volumes. All participants (n = 14) were familiar with bag-valve ventilation. Each person ven-tilated the test lung for 30 minutes. Each tidal volume was recorded for Minutes 2, 15, and 30. Grip strength was measured using a mechanical digital grip-strength tester for both the dominant and nondominant hands before and after each 30-minute trial. Each subject participated four times: using 1 hand and 2 hands with low impedance (compliance of 50 mL/cm H2O, resistance of 5 cm H2O·L·−1) and high impedance (compliance of 20 mL/cm H2O, resistance of 20 cm H2O·L·−1). The order of testing was randomly determined and a minimum 30-minute recovery time was allowed between test periods.
Results
There was no significant difference in Vr for the three measurement periods (p = 0.16). There was a significant difference in Vr for the impedance levels (p = 0.002) and for 1 hand versus 2 hands (p < 0.001). During one-hand ventilation, there was a small but significant decrease in grip strength for the dominant hand (p = 0.02), but no change in grip strength for the nondominant hand (p = 0.73).
Conclusions
The effects of lung impedance and using 2 hands for manual bag-valve ventilation were greater than the effect of fatigue on tidal volume delivery during use of man-ual bag-valve resuscitators.
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