Plaintiff's Technical Allegations:  The plaintiff alleged that the design of the halothane vaporizer in question contained a check valve assembly  that could become contaminated with a residue of halothane - thymol.  The thymol residue would cause the ball of the check valve assembly to stick in the closed position.  When the ball becomes unstuck, a surge of anesthetic gas was delivered to the patient causing an overdose.

BME Work:  The biomedical engineering portion of the investigation included design analysis of the anesthesia machine and incident reconstruction according to plaintiff theories.  The analysis demonstrated the ball check valve in question within the halothane vaporizer could not in fact become stuck closed because of a thymol build-up.  Thymol contamination was a problem in these vaporizers until a float valve retrofit was made to the vaporizers.  The float valve prevented thymol contamination and since it was implemented no more check valve contamination was reported.  The subject vaporizer had the float valve retrofit.  However, even if one assumed the check valve was stuck and during the procedure, gas was then not routed through the vaporizer, the patient would go light for lack of halothane.  If the ball suddenly became unstuck, a very small and clinically insignificant surge of halothane would result followed by the anesthetic level gradually increasing to the set value on the vaporizer.  A report was submitted and a deposition was taken before trial and during the trial.  Expert testimony was rendered in the trial.

Outcome:  The manufacturer did not bring the anesthesiologist into the suit as he had been a long term friend and supporter of the company.  The hospital had settled out of the case already but the jury was not to be told that fact for this trial.  Apparently the technical findings did not sway the jury.   The verdict favored the plaintiff.

Relevance:  Today it is the standard of care to monitor the breath by breath concentration of anesthetic gas delivered to and exhaled from a patient.  This along with other monitoring such as end-tidal CO₂, and pulse oximetry, prevent anesthetic under or overdosing.  Hospital management of physician practicing privileges is an on-going area of improvement but it varies from hospital to hospital.