Int. Adv. Otol. 2010; 6(3) 331-336

Dexmedetomidine for Controlled Hypotension In Middle Ear Surgery with Low-Flow Anesthesia.
Bayazit Dikmen, Fazilet Sahin, Dilsen Ornek, Yasar Pala, Oya Kilci, Eyup Horasanli, Mehmet Canturk  Anesthesiology and Reanimation Clinic, Ankara Training & Research Hospital, Turkey.

Objectives: Controlled hypotension is commonly used to achieve a bloodless operative field which is needed for successful middle ear surgery. Dexmedetomidine can be a potential agent in controlled hypotension. In this study we investigated efficacy of dexmedetomidine as an adjunct to induce controlled hypotension in tympanoplasty with low-flow anesthesia.

Materials and Methods: Forty patients undergoing middle ear surgery were studied. In Group D (n=20), Dexmedetomidine (0,1µg.kg-1.min-1 for 10 minutes) was administered before induction and continued with a rate between 0,2-0,7 µg.kg-1.h-1 and Group S(n=20) received normal saline with a rate of 50 ml.h-1. Infusions were stopped with the end of microsurgery.  Anesthesia was induced with thiopental and  vecuronium bromide. Maintenance of anesthesia was achieved by 1.5 % isoflurane delivered in mixture of O2 and N2O , 4.4 L.min-1 for 10 min  and then flow rate was reduced to 1 L.min-1 and isoflurane concentration increased 2 %.  20 min before the replacement of tympanic membrane greft,  N2O was discontiued and then the patients were exubated. Haemodynamic parameter, quality of the surgical field and surgeon satisfaction were evaluated.

Results: Demographic and hemodynamic datas, the quality of the surgical field and surgeon’s satisfaction  were similar. Desired level of hypotension was achieved at the 5 th min in group D, in group S it couldn’t be achieved until the 30th min.

Conclusion: Dexmedetomidine was effective in inducing consistent and sustained controlled hypotension in low-flow anesthesia during middle ear microsurgery.