Impact of Gas Delivery Systems on Imaging Studies of Human Cerebral Blood Flow

Table 1

End tidal CO₂ and respiratory rate under each gas using both circuits.

Gas	Hudson mask circuit	Mapleson A circuit
	Respiratory rate RPM	Respiratory rate RPM	ETCO2 mmHg
Medical air	14	11	38
Oxygen	11.8	13.7	33
Carbogen	13.2	16.8	42