Factors Affecting the Performance of Circle Systems Used Without Carbon Dioxide Absorption
A circle system with an attached ventilator has been used to ventilate a model lung. The reservoir bag of the system was replaced by a length of corrugated tubing attached to the ventilator outlet. A small constant flow of carbon dioxide entered the lung and tidal carbon dioxide concentrations were measured at various combinations of fresh gas flow (VF), tidal volume (VT), and respiratory frequency (f). Two separate forms of circle geometry were studied.