Dexmedetomidine Ameliorates Perioperative Neurocognitive Disorders by Suppressing Monocyte-Derived Macrophages in Mice With Preexisting Traumatic Brain Injury.

BACKGROUND: Traumatic brain injury (TBI) initiates immune responses involving infiltration of monocyte-derived macrophages (MDMs) in the injured brain tissue. These MDMs play a key role in perioperative neurocognitive disorders (PNDs). We tested the hypothesis that preanesthetic treatment with dexmedetomidine (DEX) could suppress infiltration of MDMs into the hippocampus of TBI model mice, ameliorating PND. METHODS: We first performed bone marrow transplantation from green fluorescent protein-transgenic mice to C57BL/6 mice to identify MDMs. We used only male mice for homogeneity. Four weeks after transplantation, a controlled cortical impact model of TBI was created using recipient mice. Four weeks after TBI, mice received pretreatment with DEX before general anesthesia (GA). Mice performed the Barnes maze test (8-12 mice/group) 2 weeks after GA and were euthanized for immunohistochemistry (4-5 mice/group) or immunoblotting (7 mice/group) 4 weeks after GA. RESULTS: In Barnes maze tests, TBI model mice showed longer primary latency (mean difference, 76.5 [95% confidence interval, 41.4-111.6], P < .0001 versus Naïve), primary path length (431.2 [98.5-763.9], P = .001 versus Naïve), and more primary errors (5.7 [0.62-10.7], P = .017 versus Naïve) than Naïve mice on experimental day 3. Expression of MDMs in the hippocampus was significantly increased in TBI mice compared to Naïve mice (2.1 [0.6-3.7], P = .003 versus Naïve). Expression of monocyte chemotactic protein-1 (MCP1)-positive areas in the hippocampus was significantly increased in TBI mice compared to Naïve mice (0.38 [0.09-0.68], P = .007 versus Naïve). Immunoblotting indicated significantly increased expression of interleukin-1ß in the hippocampus in TBI mice compared to Naïve mice (1.59 [0.08-3.1], P = .035 versus Naïve). In contrast, TBI mice pretreated with DEX were rescued from these changes and showed no significant difference from Naïve mice. Yohimbine, an α2 receptor antagonist, mitigated the effects of DEX (primary latency: 68.3 [36.5-100.1], P < .0001 versus TBI-DEX; primary path length: 414.9 [120.0-709.9], P = .0002 versus DEX; primary errors: 6.6 [2.1-11.2], P = .0005 versus TBI-DEX; expression of MDMs: 2.9 [1.4-4.4], P = .0001 versus TBI-DEX; expression of MCP1: 0.4 [0.05-0.67], P = .017 versus TBI-DEX; expression of interleukin-1ß: 1.8 [0.34-3.35], P = .01 versus TBI-DEX). CONCLUSIONS: Preanesthetic treatment with DEX suppressed infiltration of MDMs in the hippocampus and ameliorated PND in TBI model mice. Preanesthetic treatment with DEX appears to suppress infiltration of MDMs in the hippocampus and may lead to new treatments for PND in patients with a history of TBI.

Epidural anesthesia combined with sedation with dexmedetomidine for appendectomy in a patient with amyotrophic lateral sclerosis: a case report.

BACKGROUND: Patients with amyotrophic lateral sclerosis (ALS) present increased risks for anesthesia-related complications. We present a case of epidural anesthesia combined with sedation with dexmedetomidine for open appendectomy in a patient with ALS who refused invasive mechanical ventilation. CASE PRESENTATION: A 50-year-old man with a 3-year history of ALS was scheduled to undergo open appendectomy due to repeated appendicitis. He refused to undergo invasive mechanical ventilation using an endotracheal tube. Hence, we decided to administer epidural anesthesia combined with sedation with dexmedetomidine for anesthesia during the surgical procedure. The patient underwent open appendectomy without complications and with no pain or discomfort during surgery. There were no neurological complications at the 3-month follow-up after surgery. CONCLUSIONS: Epidural anesthesia combined with sedation with dexmedetomidine may be effective for the anesthetic management of patients who would benefit from regional anesthesia.

Differential axillary nerve block for hand or forearm soft-tissue surgery.

PURPOSE: This study determined the effective concentration of ropivacaine required to produce the type of differential block known as sensory block with mobilization, for adequate analgesia after forearm or hand soft tissue surgery by axillary brachial plexus block. METHODS: Forty-four patients were enrolled, and ultrasound-guided axillary nerve block with nerve stimulation was achieved using 16 mL of ropivacaine in total. Postoperative analgesia and sensory/motor function, side effects, the use of rescue analgesics, and the patient satisfaction score were evaluated 24 h after surgery. The effective concentration of nerve block was calculated by probit analysis. RESULTS: Eighteen patients achieved differential block and were sufficiently satisfied with the block, which was significantly better than the patient satisfaction obtained with incomplete differential block. The maximum effective concentration of 6 mL of ropivacaine needed for differential block was calculated as 0.1285 %, which meant that 71 % of the patients experienced both sensory block and maintenance of motor function. CONCLUSION: This analysis showed that 16 ml of 0.1285 % ropivacaine is suitable for achieving differential block in ultrasound-guided axillary nerve block for hand and forearm surgery.

[Three cases of ATP-induced bronchospasm during thoracic endovascular aortic repair].

We report three cases (73-year-old, 69-year-old and 76-year-old men) of bronchospasm induced by adenosine triphosphate (ATP) during thoracic endovascular aortic repair (TEVAR). Severe broncospasm occurred soon after administration of ATP to obtain transient asystole during TEVAR. All three cases were complicated with asthma or chronic obstructive pulmonary disease (COPD) before TEVAR, and airway hyper-reactivity was suspected. One case (73-year-old) required postoperative intensive care to treat bronchospasm, and the other two cases recovered during the operation. The possible mechanism of adenosine-induced bronchoconstriction is selective interaction with active mast cells with subsequent release of preformed and newly formed mediators. Careful attention should be paid when ATP is injected during TEVAR in patients with asthma or COPD.

Epidrum(®): a new device to identify the epidural space with an epidural Tuohy needle.

Epidrum(®) is an optimal pressure, loss of resistance device for identifying the epidural space. We investigated the usefulness of Epidrum versus the loss of resistance or hanging drop techniques while performing epidural anesthesia. Eighty adult patients who were scheduled for elective surgery under lumbar epidural anesthesia were randomized into two groups. The first group (Epidrum group) consisted of 40 adult patients who were scheduled for epidural anesthesia using Epidrum. The second group (control group) consisted of 40 adult patients who were scheduled for epidural anesthesia using the loss of resistance or hanging drop technique. We recorded the time required to identify the epidural space and outcomes of epidural catheterization. The attending anesthesiologists were also questioned regarding the ease of control of the Tuohy needle and of epidural space identification with each method. The time required to perform epidural anesthesia was significantly shorter in the Epidrum group than in the control group [28 s (10-76) vs. 90 s (34-185); median (interquartile range)] (p < 0.05). Tuohy needle control was significantly easier in the Epidrum group than in the control group (p < 0.05). Epidrum is useful for performing epidural anesthesia quickly while obtaining good Tuohy needle control.