Clonidine, an α₂-agonist, increases urine output and electrolyte excretion, and reduces the dose requirement of vasodilator for induced hypotension. We examined whether oral clonidine would provide these effects during hypotensive anesthesia.
Twenty patients randomly received oral clonidine either 5μg/kg(clonidine group, n＝10), or none(control group, n＝10). General anesthesia was maintained with isoflurane and 67% N₂O. During hypotensive period, mean arterial pressure(MAP) was kept at 50-60 mmHg. Urine output, urine osmolality, urinary excretion of electrolytes, and plasma ADH level were examined.
Urine output and absolute urinary excretion of potassium were greater during the first 30 minutes of hypotensive period in the clonidine group than the control group. Five patients in the control group and one in the clonidine group had no urine output during the hypotensive period(p＜0.05). Absolute urinary excretion of sodium and potassium increased in the control group after MAP recovered. However, plasma ADH levels did not change over time in both groups, and were similar between groups. No difference was found between the two groups in the dose requirement of nicardipine during hypotensive period.
Oral preanesthetic medication of clonidine 5μg/kg provided a diuretic effect during hypotensive anesthesia.

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A 66 year-old male, who had pancreatic and adrenal tumor with severe HOCM, underwent a surgical tumor resection under general anesthesia with epidural block. Transthoracic echocardiography showed LVd/LVs 38/15mm, IVS 27mm, LVPW 16mm, asymmetric septal hypertrophy, and ejection fraction of 67%.
Narrow safety ranges of preload and afterload, increasing myocardial contractility which worsens left ventricular outflow tract obstruction in HOCM may cause the circulatory management more difficult. FloTrac® monitoring system is less invasive and able to monitor arterial pressure-based cardiac output(APCO) and stroke volume variation continuously.
Using FloTrac® monitoring system, safe and stable perioperative management was achieved in spite of his severe HOCM.

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