Renal function and histology after acute hemorrhage in rats under dexmedetomidine action

Perioperative acute kidney injury: The renoprotective effect and mechanism of dexmedetomidine

Dexmedetomidine (DEX) is a highly selective and potent α2-adrenoceptor (α2-AR) agonist that is widely used as a clinical anesthetic to induce anxiolytic, sedative, and analgesic effects. In recent years, a growing body of evidence has demonstrated that DEX protects against acute kidney injury (AKI) caused by sepsis, drugs, surgery, and ischemia-reperfusion (I/R) in organs or tissues, indicating its potential role in the prevention and treatment of AKI. In this review, we summarized the evidence of the renoprotective effects of DEX on different models of AKI and explored the mechanism. We found that the renoprotective effects of DEX mainly involved antisympathetic effects, reducing inflammatory reactions and oxidative stress, reducing apoptosis, increasing autophagy, reducing ferroptosis, protecting renal tubular epithelial cells (RTECs), and inhibiting renal fibrosis. Thus, the use of DEX is a promising strategy for the management and treatment of perioperative AKI. The aim of this review is to further clarify the renoprotective mechanism of DEX to provide a theoretical basis for its use in basic research in various AKI models, clinical management, and the treatment of perioperative AKI.

The dose-related effects of dexmedetomidine on renal functions and serum neutrophil gelatinase-associated lipocalin values after coronary artery bypass grafting: a randomized, triple-blind, placebo-controlled study

OBJECTIVES

Acute kidney failure after coronary artery bypass grafting (CABG) is a serious complication that increases morbidity and mortality rates. Early detection and prevention of this complication are very important. A novel biomarker named neutrophil gelatinase-associated lipocalin (NGAL) can play an important role in early diagnosis of acute kidney injury. Recent studies on the favourable effects of Dexmedetomidine on cardiac surgery have been published. The aim of this study is to investigate whether there is a dose-dependent positive effect of Dexmedetomidine on neutrophil gelatinase-associated lipocalin levels and renal functions when used after CABG.

METHODS

Our randomized, triple-blinded, placebo-controlled study was conducted among 295 patients scheduled for CABG surgery between August 2009 and March 2011 in a tertiary cardiac and vascular surgery clinic. A total of 90 consecutive patients who met inclusion criteria were randomized and divided into three groups. The first group received a placebo. The second and the third groups received 4 and 8 µg/cc concentration of the Dexmedetomidine infusion, respectively. Infusion rates were regulated to obtain sedation with a Ramsey sedation score of 2 or 3. Patients were regrouped according to the total Dexmedetomidine dose. Statistical analyses of variables including serum neutrophil gelatinase-associated lipocalin values and conventional renal function tests were made for all six possibilities before the blind was broken.

RESULTS

Results of conventional renal function tests were not significantly different. However, neutrophil gelatinase-associated lipocalin levels for the first postoperative day for placebo, low-dose and high-dose Dexmedetomidine groups were 176.8 ± 145.9, 97.7 ± 63.4 and 67.3 ± 10.9 ng/ml, respectively. These values were significantly different among the groups (P <0.001).

CONCLUSIONS

In our study, we found that Dexmedetomidine infusion for sedation after CABG under cardiopulmonary bypass can be useful in the prevention of kidney injury. Conventional renal function tests, including blood urea nitrogen, serum creatinine, urine output and creatinine clearance rate measurements typically may not detect the development of acute kidney dysfunction in the first 48-h postoperative period. Differences were detected in renal function in the early postoperative period and the development of acute kidney injury, as determined by measurements of blood NGAL levels, was significant and dose-dependent.

Molecular targets and mechanism of action of dexmedetomidine in treatment of ischemia/reperfusion injury

Dexmedetomidine (DEX), a highly specific α2-adrenergic agonist, which exhibits anaesthetic-sparing, analgesia and sympatholytic properties. DEX modulates gene expression, channel activation, transmitter release, inflammatory processes and apoptotic and necrotic cell death. It has also been demonstrated to have protective effects in a variety of animal models of ischemia/reperfusion (I/R) injury, including the intestine, myocardial, renal, lung, cerebral and liver. The broad spectrum of biological activities associated with DEX continues to expand, and its diverse effects suggest that it may offer a novel therapeutic approach for the treatment of human diseases with I/R involvement.

Dexmedetomidine infusion for analgesia up to 48 hours after lung surgery performed by lateral thoracotomy

Patients undergoing a lateral thoracotomy for pulmonary resection have moderate to severe pain postoperatively that is often treated with opioids. Opioid side effects such as respiratory depression can be devastating in patients with already compromised respiratory function. This prospective double-blinded clinical trial examined the analgesic effects and safety of a dexmedetomidine infusion for postthoracotomy patients when administered on a telemetry nursing floor, 24 to 48 hours after surgery, to determine if the drug's known early opioid-sparing properties were maintained. Thirty-eight thoracotomy patients were administered dexmedetomidine intraoperatively and overnight postoperatively and then randomized to receive placebo or dexmedetomidine titrated from 0.1 to 0.5 μg·kg·h(-1) the day following surgery for up to 24 hours on a telemetry floor. Opioids via a patient-controlled analgesia pump were available for both groups, and vital signs including transcutaneous carbon dioxide, pulse oximetry, respiratory rate, and pain and sedation scores were monitored. The dexmedetomidine group used 41% less opioids but achieved pain scores equal to those of the placebo group. The mean heart rate and systolic blood pressure were lower in the dexmedetomidine group but sedation scores were better. The mean respiratory rate and oxygen saturation were similar in the two groups. Mild hypercarbia occurred in both groups, but periods of significant respiratory depression were noted only in the placebo group. Significant hypotension was noted in one patient in the dexmedetomidine group in conjunction with concomitant administration of a beta-blocker agent. The placebo group reported a higher number of opioid-related adverse events. In conclusion, the known opioid-sparing properties of dexmedetomidine in the immediate postoperative period are maintained over 48 hours.

The effects of dexmedetomidine on mesenteric arterial occlusion-associated gut ischemia and reperfusion-induced gut and kidney injury in rabbits

OBJECTIVE

We assessed the antioxidant activity of dexmedetomidine (Dex) administered during the ischemic period in a rabbit model of mesenteric ischemia/reperfusion (I/R) injury using biochemical and histopathological methods.

METHODS

A total of 24 male New Zealand white rabbits weighing between 2.5 and 3.0 kg were randomly divided into three groups: the sham group (Group S, n = 8), the I/R group (Group I/R, n = 8), and the I/R plus Dex treatment group (Group Dex, n = 8). In the I/R group, ischemia was achieved with 60 min of mesenteric occlusion. The sham group provided normal basal values. The rabbits in Group I/R were operated to achieve I/R. Group Dex received intravenous Dex 30 min after the commencement of reperfusion (10 μg/kg Dex was infused within 10 min, and then a maintenance dose of 10 μg/kg/h Dex was infused intravenously). For the measurement of tissue malondialdehyde, total antioxidant status, total oxidant status, lipid hydroperoxide levels, superoxide dismutase, catalase, and myeloperoxidase activity levels in the renal tissue samples of animals, the rabbits in each group were sacrificed 3 h after reperfusion. The histopathological examination scores were determined using the intestinal and renal tissues.

RESULTS

The mean malondialdehyde, total oxidant status, myeloperoxidase, and lipid hydroperoxide levels were significantly higher in Group I/R than in Groups S and Dex (P < 0.05). There also were significant decreases in the mean total antioxidant status, catalase, and superoxide dismutase activities in Group I/R compared with Groups S and Dex (P < 0.05). The histopathological examination scores of the intestinal and renal tissues were significantly higher in Group I/R compared with Groups S and Dex (P < 0.05).

CONCLUSION

Dex treatment may have biochemical and histopathological benefits by preventing I/R-related cellular damage of intestinal and renal tissues as shown in an experimental mesenteric ischemia model. The preference to use Dex for anesthesia during the mesenteric ischemia procedure may attenuate I/R injury in intestinal and renal tissues.

The effects of intraoperative infusion of dexmedetomidine on early renal function after percutaneous nephrolithotomy

BACKGROUND

Percutaneous nephrolithotomy (PCNL) may interfere with renal function because of continuous fluid irrigation and compression. The aim of this study was to evaluate the effects of an intraoperative infusion of dexmedetomidine on renal function in patients undergoing PCNL.

METHODS

This study included 40 patients between the ages of 18 and 65 years who underwent PCNL. After induction of anesthesia, we administered 100 ml of normal saline to the patients in the control group (n=20) and 1 mcg/kg dexmedetomidine in 100 ml of normal saline to the patients in the dexmedetomidine group (n=20) over 10 min. Throughout the surgery, 1 mcg/kg/h dexmedetomidine and 1 ml/kg/h normal saline infusions were given to the dexmedetomidine and control groups, respectively. Renal function, electrolytes, serum levels of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C were analyzed after induction and post-operatively at 2, 8 and 24 h. Renin levels and blood gas analyses were performed after induction and before extubation.

RESULTS

No statistically significant differences were found between the two groups with regard to renal function, creatinine clearance (CrCl), NGAL, cystatin C and serum electrolyte levels at 0, 2, 8 and 24 h post-operatively. End-surgery renin levels in the dexmedetomidine group were significantly lower than the baseline levels in the control group.

CONCLUSION

In PCNL, an intraoperative infusion of dexmedetomidine was not found to have beneficial effects on CrCl, NGAL or cystatin C levels early after the procedure; however, it reduced renin levels.