Perioperative hypothermia causes several complications, and in particular, is more hazardous in elderly patients. Hypothermia during regional anesthesia is often ignored. We investigated the effect of IV midazolam or atropine premedication on core hypothermia in geriatric patients undergoing transurethral procedures via spinal anesthesia.

Forty-five elderly (65-92 years old), ASA I or II patients about to undergo transurethral procedures, such as prostate or bladder tumor removal were enrolled into this study. In all cases, standard spinal anesthesia was administered. The control group received no premedication, the midazolam group 0.02 mg/kg of midazolam, and the atropine group 5 µg/kg of atropine, respectively just before spinal anesthesia. Core temperature was measured at the right tympanic membrane before anesthesia, at 10 and 30 min later, at the end of anesthesia, and 30 min after recovery from anesthesia.

Reduction of core temperature from the basal value, after 10 and 30 min of anesthesia, at the end of anesthesia, at 30 min after anesthesia during post-operative care unit in the control group were 0.31, 0.61, 0.5, and 0.42℃, respectively; 0.41, 0.61, 0.9, 0.65℃ in the midazolam group; and 0.15, 0.29, 0.37, 0.47℃ in the atropine group. When compared with no premedication, midazolam administration was associated with a significantly lower core temperature at the end of anesthesia. Atropine administration was associated with a significantly higher core temperature than the midazolam group after 10 and 30 min of anesthesia, and at the end of anesthesia, and the untreated control group after 10 and 30 min of anesthesia.

IV premedicant midazolam decreased core temperature; however, atropine administration significantly reduced the magnitude of hypothermia associated with spinal anesthesia in geriatric patients.