[The effect of blood conservation techniques on the plasma concentration and elimination of midazolam in patients undergoing hip joint surgery].
OBJECTIVE
The question was to evaluate whether haemodilution or intraoperative autotransfusion have an influence on plasma levels and clearance of midazolam.


METHODS
The study was designed as a prospective evaluation of patients with total hip joint replacement. The patients received neuroleptanalgesia supplemented with enflurane. After induction of anaesthesia with midazolam (0.1 mg/kg body weight) haemodilution procedure was started. During surgery a cell saver was used for blood salvage. In the recovery room drainage blood was also being processed by a cell saver.


METHODS
The study includes 10 patients belonging to ASA-group II with an average weight of 79.4 kg (53-100 kg), at an average age of 57.9 years (44-68 years).


RESULTS
Midazolam was measured in patient blood and in autologous blood units by gas chromatography. 151 micrograms of midazolam, i.e. 1.8% of the initial dose was retransfused in hemodilution blood. By processing of blood in the cell saver, 99.5% of the amount of midazolam found in the sample unit was eliminated. The maximum quantity was 5.5 micrograms in the washed autologous red cell concentrate.


CONCLUSIONS
Considering the analytic limit of 2 micrograms/l of midazolam in plasma, retransfusion of autologous blood cannot influence the plasma concentration of midazolam. Therefore, there is no risk of re-sedation in retransfusing autologous blood postoperatively.
Krier
C
C
Klinik für Anästhesiologie und operative Intensivmedizin, Katharinenhospital, Stuttgart.
Henn-Beilharz
A
A
Ritter
A
A
Klotz
U
U
D000368:Aged; D016063:Blood Loss, Surgical; D001804:Blood Transfusion, Autologous / Q000295:instrumentation / Q000379:methods*; D002469:Cell Separation / Q000295:instrumentation*; D005260:Female; D006438:Hemodilution; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008874:Midazolam / Q000097:blood* / Q000493:pharmacokinetics; D008875:Middle Aged; D011446:Prospective Studies
D008874:Midazolam
Einflüsse fremdblutsparender Verfahren auf Plasmaspiegel und Elimination von Midazolam bei Patienten mit Hüftgelenksoperationen.