[1999]MANUAL VENTILATION (MV) DURING ANESTHESIA: EFFECTS OF BREATHING BAG (BB) SIZE AND SHAPE.
Amy Wehrman RN, Kristy Bates CRTT, Robert Campbell RRT, Richard Branson RRT. University of Cincinnati, Cincinnati, OH.
Background: During anesthesia, MV is typically provided using a 3-L BB. Effective ventilation depends on fresh gas flow, clinician skill, pt impedance, and BB characteristics. We evaluated 3 types of BB during MV by 11 CRNA students. Method: An anesthesia ventilator and 40
²
coaxial circuit (F circuit, King Systems) was connected to a TTL with PneuView (Michigan Instruments). Volunteers (VOL) (6 men, 5 women) ventilated the TTL using 1) a standard 3-L BB, 2) a standard 2-L BB, and 3) a 2-L hourglass shaped (HS) BB. VOLs were instructed to ventilate the lung at VT of 0.8 L and f of 12 b/min. PneuView measured airway pressures, VT, VE, peak flow, f, and inspiratory time. Lung C was set at 0.05 L/cmH2O and R was set at 5 cmH2O/L/s. Hand size was recorded. VOLs rated ease of use and perceived BB efficiency. Values were averaged over one minute.
Results: Results are mean ± SD. ANOVA for repeated measures was used to compare variables using each BB.
BAG
Gender
2- L Std
3-L Std
2-L HS
VT (L)
All
1.01 (0.11)
0.99 (0.11)
0.89 (0.08)*
Men
1.06 (0.12)
1.03 (0.17)
0.94 (0.07)*
Women
0.96 (0.11)
0.98 (0.10)
0.87 (0.09)*
PIP
All
22.7 (3.0)
21.2 (2.5)
20.9 (2.3)
(cmH2O)
Men
24.5 (3.7)
22.4 (4.2)
22.4 (1.4)
Women
21.9 (3.4)
20.6 (1.5)
20.2 (2.4)
* p < 0.05 vs 2-L and 3-L standard bags
8 of 11 VOLs preferred the 2-L HS BB. 3 VOLs preferred the std 2-L BB. Ease of use and perceived control over ventilation was better with the 2-L BBs. Conclusion: VT provided with 2-L HS BB was smaller and closer to the 0.8 L target compared to other BBs. Differences in VT were statistically, but not clinically significant. The 2-L HS BB was preferred for ease of use compared to std 2-L and 3-L BBs.
