| BACKGROUND: Deliberate hypotension can reduce bleeding and improve the surgical field and reduce the risk of surgery. Vasoactive drugs have reflex tachycardia, rebound hypertension, increased myocardial oxygen consumption and other negative factors. Anesthetic and analgesic drugs have burst suppression, opioid poisoning, increased incidence of postoperative cognitive dysfunction and other risks. Activatingа2-receptor can inhibit activation of catecholamine, with sedative, analgesic and anti-sympathetic effects. Dexmedetomidine hydrochloride is a new setа2-receptor agonists,supporting a steady blood pressure during anesthesia, reducing myocardial oxygen consumption and so on. The present study in spinal surgery was conducted to investigate the safety and feasibility of deliberate hypotension with dexmedetomidine hydrochloride ,as well as the effects on cerebral oxygen metabolism rate and postoperative cognitive dysfunction.METHODS: Sixty ASAⅡ-Ⅲpatients aged 36-67 years who underwent posterior lumbar interbody fusion were randomly divided into two groups, dexmedetomidine hydrochloride group(D group ) and nitroglycerin group(N group),30 in each group. Both groups were anesthetized with sevoflurane after the same anesthesia induction. Sevoflurane was adjusted to maintain the bispectral number at 50±5 , atracurium was administered as a continuous infusion of 0.2mg/(kg·h) to maintain muscle loose and 0.05-0.1 mg fentanyl was given as required. All patients received deliberate hypotension after lumbar exposed. In group D, intravenous administration of dexmedetomidine hydrochloride 0.5μg/kg and then followed by infusion of 0.2-0.7μg/(kg·h) for deliberate hypotensionl ,and the patients of group N received nitroglycerin 2μg/kgfollowed by 3-6 ug/(kg·min). The target of deliberate hypotension was in order to reduce the mean arterial pressure 25-30%, which was maintained for 70 minutes. Record mean arterial pressure, heart rate, electro-cardiography, bispectral index before and after 5,10,15 minutes of using drugs ,and after 5,10,15 minutes of stopping drugs. Arterial, jugular and vein blood samples were taken synchronously for measuring blood gas, blood glucose and plasma cortisol concentration. Record the bleeding intraoperative and 12 hours after surgery, mini-mental state examination 24 hours after surgery and the incidence of postoperative cognitive dysfunction.RESULTS: 1. Two groups of patients reached target mean arterial pressure, in 5 ~ 15min, the difference were not statistically significant; Heart rate decreased synchronously in group D without reflex tachycardia and rebound, the differences were statistically significant compared with group N.2. Bispectral index values in group D decreased by about 13.5% after 5 minutes of using drugs, and decreased 14.1% than N group at corresponding time points. Sevoflurane concentration decreased by about 19.3% from 10 minutes of using drugs to 10 minutes of stopping drugs in group D compared with group N.3. There were no significant change in blood glucose and plasma cortisol concentration in group D during the lowering of blood pressure, while the N group, there have been a rising trend; Bleeding intraoperative and 12 hours after surgery decreased by approximately 24.2% and 18.6% compared with N group.4. During the lowering of blood pressure, arterial oxygen content, jugular vein oxygen content, cerebral oxygen metabolism rate in two groups of patients were within the normal range, sets of mini-mental state examination and incidence of postoperative cognitive dysfunction had no significant difference in two groups.CONCLUSIONS:Given dexmedetomidine hydrochloride deliberate hypotension is safe and feasible; patients with heart rate, mean arterial pressure decreased steadily, without reflex tachycardia and complex pressure rebound phenomenon. Cerebral oxygen metabolism rate and postoperative cognitive dysfunction had no significant effect; It can further reduce the bleeding and save the amount of anesthetic drugs. |
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