To \& Fro Versus Mapleson D Circuit – A Comparative Study of Capillary Blood Gas.

 The comparative study of the modified To \& Fro circuit and the Mapleson D circuit blood gas technique was chosen as a method of comparison due to its simplicity and no injury to vessel. Using constant FGF, Fi02 and minute ventilation, it was found that the modified To \& Fro circuit showed lower pC02 than the Mapleson D circuit significantly.