Microsystems for measurement and dosage of volatile anesthetics and respirative gases in anesthetic equipment

The state-of-the art in an anesthetic equipment uses a minimal flow concept to optimize anesthetic liquid consumption to cut costs and to protect the environment from anesthetic gases obtaining fluorine chlorine carbon compounds. In this work, a multi-channel sensing system is presented, which is capable of measuring the concentration of anesthetic gases in the mainstream of a respiratory circle. This system is based on non-dispersive infrared absorption spectroscopy and measures the concentration of carbon dioxide, nitrous oxide and any composition containing two of the following volatile anesthetics: Enfluran, Isofluran and Halothan. Furthermore, a microdosage system consisting of a micropump and a micronebulizer was developed. Both components are based on silicon technology. This system allows to adjust the anesthetic liquid mass flow from about 4 /spl mu/J/min up to about 1000 /spl mu/l/min. Both systems were tested as subsystems of the anesthetic apparatus Physioflex.