RESUMO
The effect of changing the fresh gas flow [FGF] [70, 100 and 150 ml/kg/min.] in the Bain system during spontaneous respiration was studied in 55 adult male patients [ASA 1] after using the standard Magill system [control] for 20 minutes at a fixed FGF of 70 ml/kg/min. Bain system at FGF [Vf] of 100 ml/kg/min. was comparable with Magill with the least percentage of change in PaCO3 and expired minute volume [V]. VF/VE ratio showed a insignificant correlation coefficient [r=-0.35] when correlated with PaCO2 values. Therefore, it was recommended that FGF of 100 ml/kg/min. is ideal for Bain system to prevent rebreathing during spontaneous respiration. Also, the FGF should be expressed in an absolute value, i.e. ml/min. and not as a multiple of minute volume