Mass spectrometer artifact: simultaneous detection of two volatile anesthetics.

In several cases, a mass spectrometer indicated that both enflurane and isoflurane were being detected while only isoflurane was in use. The concentration of expired enflurane reported was always higher than the inspired concentration, but never exceeded 0.66% regardless of the concentration of isoflurane. Such mass spectrometer readings may be evidence of vaporizer contamination or malfunction of the vaporizer; however, in this case, the mass spectrometer was found to be out of calibration. Because mass spectrometers are recent additions to clinical equipment, procedures for routine calibration and maintenance must be carefully scrutinized and evaluated.

Recognition of mixed anesthetic agents by mass spectrometer during anesthesia.

Anesthetic agents are sometimes added to the wrong vaporizer on an anesthesia machine. As a result, the vaporizer may deliver a mixture of anesthetic agents at concentrations inappropriate for use on a patient. However, untoward clinical complications related to vaporizers can be prevented with a time-shared mass spectrometer. This device accurately and rapidly indicates the gases and gas concentrations present in a vaporizer.