The effects of dexmedetomidine on liver ischemia-reperfusion injury in rats.

BACKGROUND: Ischemia-reperfusion (IR) injury of the liver may cause various types of damage to hepatic tissues. It can affect the prognosis of patients and the success of an operation. Dexmedetomidine is a selective α2 receptor agonist. We investigated whether dexmedetomidine provides protection against IR-induced liver injury in rats. METHODS: Forty rats were divided equally into four groups. In group 1, the liver was manipulated after the laparotomy, and no occlusion of the vessels of the liver was performed. In group 2, once the abdomen was opened, 60 min of ischemia and 60 min of reperfusion were applied according to the segmental hepatic ischemia model. In group 3, 10 µg/kg of dexmedetomidine was injected into the peritoneal cavity 30 min before ischemia. In group 4, 100 µg/kg of dexmedetomidine was injected into the peritoneal cavity 30 min before ischemia. Further procedures in groups 3 and 4 were the same as those of group 2. After the experiment was completed, the rats were killed. Liver tissues were removed and stored until biochemical and histologic assessments were performed. RESULTS: The malondialdehyde level in group 2 was higher than that of groups 1, 3, and 4 (P = 0.001, P = 0.000, and P = 0.000, respectively). Superoxide dismutase, catalase, and glutathione levels in group 2 were lower than those in group 1 (P = 0.001, P = 0.027, and P = 0.014, respectively). Superoxide dismutase and catalase levels in group 4 were higher than those in group 2 (P = 0.002 and P = 0.000, respectively). GSH levels in groups 3 and 4 were higher than those in group 2 (P = 0.049 and P = 0.006, respectively). A lower glutathione peroxidase level was detected in groups 2 and 3 than that in group 1 (P = 000). Group 4 demonstrated an increase in glutathione peroxidase levels compared with group 3 (P = 0.014). The histologic injury scores in groups 2-4 were higher than those in group 1 (P = 0.003, P = 0.002, and P = 0.001, respectively). However, the histologic injury scores were lower in groups 3 and 4 than those in group 2 (P = 0.003 and P = 0.002, respectively). CONCLUSIONS: This study showed that dexmedetomidine may protect the liver against IR injury in rats.

Instillation of skin, nephrostomy tract, and renal puncture site with ropivacaine decreases pain and improves ventilatory function after percutaneous nephrolithotomy.

BACKGROUND AND PURPOSE: Pain after percutaneous nephrolithotomy (PCNL) is well investigated, but no optimal management strategy has yet been defined. Ventilatory changes after uncomplicated PCNL remain obscure. We investigated whether pain can be managed with a combination of a parenteral non-narcotic drug and instillation of a local anesthetic into the operative field. We also measured ventilatory changes early after PCNL to determine whether this analgesic modality improves ventilatory status. PATIENTS AND METHODS: In a randomized blinded study, 34 well-matched patients underwent PCNL with single subcostal access. At the end of the operation, 30 mL of either 0.02% ropivacaine or saline was instilled into the renal puncture site, nephrostomy tract, and skin. Postoperatively, patients received parenteral metamizol (dipyrone) (500 mg/dose) on demand. Pain visual analog score (VAS), peak expiratory flow rate (PEF), and blood-gas analysis were performed at 2, 6, and 24 hours postoperatively. The number of analgesic doses required was recorded. RESULTS: The VAS at 6 hours, time to first analgesic demand, and total analgesic need were significantly lower (P=0.001, 0.008, and 0.001, respectively) in the ropivacaine group, whereas the PEF at 2 and 6 hours was significantly higher (P=0.001 for each). Analgesic use in the first 12 and 24 hours was lower in this group. Blood-gas analysis was within the normal range in both groups. Time of surgery and hemoglobin decrease were not significantly different. CONCLUSIONS: A decrease in PEF indicating restricted ventilation appears early after PCNL. Because these patients were chosen carefully to have normal function preoperatively, this decrease was attributed to nociception. A combination of ropivacaine instillation with metamizol decreases pain and analgesic use and improves PEF more than use of metamizol alone. Such a multimodal pain-management strategy is effective in minimizing postoperative opioid use with proper pain management, resulting in better ventilation.