A patient was undergoing a series of surgical procedures requiring general anesthetic. At the third procedure he suddenly became hypotensive with marked cardiac arrhythmia. In addition his breathing became difficuft due to extensive bronchocorstriction and obstructive laryngeal edema. Despite the efforts of the surgical team the patient developed severe and permanent brain damage due to hypoxernia. It was subsequently discovered that the patient had developed IgG antibodies to the anesthetic gas and this had resulted in an anaphylactoid response to the anesthetic. What type of reaction caused this condition?