Typically the fresh gas flow emerges from the common gas outlet, a specific outlet on the anaesthetic machine to which the breathing attachment is then connected.
Some older forms of breathing attachment, such as the Magill attachment, require high fresh gas flows (e.g. 7 litres/min) to prevent the patient from rebreathing their own expired carbon dioxide. More modern systems, e.g. the circle breathing attachment, use soda lime to absorb carbon dioxide, so that expired gas becomes suitable to re-use. With a very efficient circle system, the fresh gas flow may be reduced to the patient's minimum oxygen requirements (e.g. 250ml/min), plus a little volatile.
US Patent Issued to Cardiac Pacemakers on June 28 for "Diagnosis and/ or Therapy Using Blood Chemistry/ expired Gas Parameter Analysis" (Minnesota Inventors)
Jul 02, 2011; ALEXANDRIA, Va., July 2 -- United States Patent no. 7,970,470, issued on June 28, was assigned to Cardiac Pacemakers Inc. (St....