Incidence of histamine release after the administration of midazolam-ketamine in allergic patients.

OBJECTIVE

We examined the effects of midazolam-ketamine which was used during the induction of anesthesia against histamine release, skin reactions and hemodynamic changes in patients with a history of allergy.

SUBJECTS: Forty allergic patients and 40 non-allergic patients undergoing oral surgery were examined.

METHODS

Midazolam ketamine was used for the induction of anesthesia in 40 patients with a history of allergy (M-K group) and thiamylal was used for the induction of anesthesia in 40 patients without any history of allergy (BARB group). Venous blood samples were obtained before induction as a control and 0.5, 1, 3, 5 minutes after the administration of each drug in order to measure the plasma histamine level. In addition, any observed hemodynamic changes were simultaneously recorded. The plasma histamine level was measured using the HPLC (high performance liquid chromatography) post-label system.

RESULTS

The incidence of histamine release, skin reactions and hemodynamic changes were 37.5%, 10.0% and 7.5%, in the M-K group, and 40.0%, 12.5% and 12.5%, in the BARB group, respectively. Although the mean basal plasma histamine level in the M-K group (0.46 +/- 0.23 ng/ml) who had a history of allergy was much higher than that in the BARB group (0.28 +/- 0.17 ng/ml) (p < 0.001), the incidence of histamine release and clinical symptoms were similar between the two groups.

CONCLUSIONS

The induction of anesthesia with midazolam-ketamine was thus found to be a valuable method for allergic patients, because the incidence of histamine release, skin reactions and hemodynamic changes in allergic patients were similar to those in non-allergic patients induced by thiamylal and no significant changes were observed in the plasma histamine level after the administration of midazolam-ketamine in spite of the high level of basal plasma histamine.