Zhibin Zhao

The effects of dexmedetomidine pretreatment on the pro- and anti-inflammation systems after spinal cord injury in rats

Excessive inflammatory responses play important roles in the aggravation of secondary damage to an injured spinal cord. Dexmedetomidine (DEX), a selective α2-adrenoceptor agonist, has recently been implied to be neuroprotective in clinical anesthesia, but the underlying mechanism is elusive. As signaling through Toll-like receptor 4 (TLR4) and nicotinic receptors (nAChRs, notably α7nAChR) play important roles in the pro- and anti-inflammation systems in the central nervous system, respectively, this study investigated whether and how they were modulated by DEX pretreatment in a rat model of spinal cord compression. The model was used to mimic perioperative compressive spinal cord injury (SCI) during spinal correction. DEX preconditioning improved locomotor scores after SCI, which was accompanied by increased α7nAChR and acetylcholine (Ach, an endogenous ligand of α7nAChR) expression as well as PI3K/Akt activation. However, there was a decrease in Ly6h (a negative regulator for α7nAChR trafficking), TLR4, PU.1 (a critical transcriptional regulator of TLR4), HMGB1 (an endogenous ligand of TLR4), and caspase 3-positive cells, which was prevented by intrathecal preconditioning with antagonists of either α2R, α7nAChR or PI3K/Akt. In addition, application of an α7nAChR agonist produced effects similar to those of DEX after SCI, while application of an α7nAChR antagonist reversed these effects. Furthermore, both α7nAChR and TLR4 were mainly co-expressed in NeuN-positive cells of the spinal ventral horn, but not in microglia or astrocytes after SCI. These findings imply that the α2R/PI3K/Akt/Ly6h and α7nAChR/PI3K/Akt/PU.1 cascades are required for upregulated α7nAChR and downregulated TLR4 expression by DEX pretreatment, respectively, which provided a unique insight into understanding DEX-mediated neuroprotection.

Does ultrasonographic measurement of the inferior vena cava diameter correlate with central venous pressure in the assessment of intravascular volume in patients undergoing gastrointestinal surgery

BACKGROUND Ultrasonography has been suggested as a useful noninvasive tool for the detection of hypovolemia in critically ill patients. Hypovolemia after preoperative fasting and bowel preparation may compromise hemodynamic function during gastrointestinal surgery. However, there are few data comparing ultrasonographic examination of the inferior vena cava (IVC) diameter with central venous pressure (CVP) measurement in patients undergoing gastrointestinal surgery in the assessment of intravascular volume status. MATERIALS AND METHODS Forty American Society of Anesthesiologists I-II patients who underwent elective gastrointestinal surgery and 32 healthy volunteers were enrolled in the study. The IVC diameters, both during expiration (IVCe) and inspiration (IVCi), and right ventricle (RV) were measured with ultrasonography in patients both before and after fluid resuscitation. Volunteers were also measured during the time they participated in the study. RESULTS Forty patients (mean age 51 y; 45% female) and 32 volunteers (mean age 46 y; 44% female) underwent IVC and RV sonographic measurements. The diameters of the IVCe, IVCi, and RV in patients (1.83, 1.34, and 3.23 cm) were significantly lower compared with those of healthy volunteers (1.18, 0.62, and 2.71 cm). After fluid resuscitation, IVCe, IVCi, and RV in hypovolemic patients (1.75, 1.25, and 3.27 cm) significantly increased. The pre-IVCe and the post-IVCe were closely correlated to the CVP (r = 0.585 and r = 0.609, respectively). Similarly, the pre-RV and the post-RV were correlated to the CVP (r = 0.347 and r = 0.439, respectively). CONCLUSIONS Our data demonstrate that the IVC and RV diameters are consistently low in patients undergoing gastrointestinal surgery when compared with healthy subjects. Ultrasonographic measurements of the IVC and RV diameters are useful supplement of CVP for the evaluation of preoperative patients with hypovolemia.

Ultrasonographic measurements of the inferior vena cava variation as a predictor of fluid responsiveness in patients undergoing anesthesia for surgery

BACKGROUND Both hypovolemia and hypervolemia are connected with increased morbidity and mortality in the treatment and prognosis of patients. An accurate assessment of volume state allows the optimization of organ perfusion and oxygen supply. Recently, ultrasonography has been used to detect hypovolemia in critically ill patients and perioperative patients. The objective of our study was to assess the correlation between inferior vena cava (IVC) variation obtained with ultrasound and stroke volume variation (SVV) measured by the Vigileo/FloTrac monitor, as fluid responsiveness indicators, in patients undergoing anesthesia for surgery. METHODS Forty patients (American Society of Anesthesiologists grades I and II) scheduled for elective gastrointestinal surgery were enrolled in our study. After anesthesia induction, 6% hydroxyethyl starch solution was administered to patients as an intravenous (IV) fluid. The IVC diameters were measured with ultrasonography. SVV and stroke volume index (SVI) were obtained from the Vigileo monitor. All data were collected both before and after fluid challenge. RESULTS Forty patients underwent IVC sonographic measurements and SVV calculation. After fluid challenge, mean arterial pressure, central venous pressure, SVI, and IVC diameters increased significantly, whereas SVV decreased markedly. The correlation coefficient between the increase in SVI and the baseline of IVC variation after an IV fluid was 0.710, and receiver operating characteristic (ROC) curve was 0.85. The correlation coefficient between the increase in SVI and the baseline of SVV was 0.803 with an ROC curve of 0.93. Central venous pressure had no significant correlation with SVI. CONCLUSIONS Our data show that IVC variation and SVV proved to be reliable predictors of fluid responsiveness in patients undergoing anesthesia for surgery with mechanical ventilation.

Ultrasonographic measurement of the subclavian vein diameter for assessment of intravascular volume status in patients undergoing gastrointestinal surgery: comparison with central venous pressure.

BACKGROUND Previous studies have demonstrated that ultrasonographic measurement of the inferior vena cava diameter is a useful tool for the evaluation of intravascular volume status in preoperative patients. However, ultrasonographic measurement of inferior vena cava diameter could be limited by factors including obesity, bowel gas, or complex abdominal wounds. Our study sought to determine whether subclavian vein (SCV) diameter measured by ultrasound correlate with central venous pressure (CVP), as another indicator of intravascular volume status in patients undergoing gastrointestinal surgery. METHODS Forty patients (American Society of Anesthesiologists I-II) who underwent elective gastrointestinal surgery and 40 healthy volunteers were enrolled in the study. In the patient group, SCV diameters, during both expiration (dSCVe) and inspiration (dSCVi), were measured with ultrasonography before and after fluid resuscitation. Volunteer baseline measurements were conducted without liquid therapy and the subsequent measurement. RESULTS Forty patients (mean age 46 y; 40% female) and 40 volunteers (mean age 43 y; 45% female) underwent SCV sonographic measurements. The average diameters of the SCVe and SCVi in hypovolemic patients (0.68, 0.48 cm) were significantly lower as compared with the SCVe and SCVi diameters of healthy volunteers (0.92, 0.73 cm), whereas the SCV-collapsibility index (0.35) was higher in the hypovolemic patients as compared with the healthy volunteers (0.20). After fluid resuscitation, the SCVe and SCVi diameters in hypovolemic patients (0.88, 0.67 cm) significantly increased, whereas the SCV-collapsibility index decreased (0.23). The pre-SCVe and the post-SCVe were closely correlated to the CVP (R = 0.612 and R = 0.547, respectively). Similarly, the pre-SCVi and the post-SCVi were correlated to the CVP (R = 0.452 and R = 0.507, respectively). CONCLUSIONS SCV diameter is consistently low in patients undergoing gastrointestinal surgery as compared with healthy subjects. Measuring the SCV diameter maybe an important addition to the ultrasonographic evaluation of hypovolemia and other potentially volume-depleted patients.

Transesophageal Echocardiographic Measurements of the Superior Vena Cava for Predicting Fluid Responsiveness in Patients Undergoing Invasive Positive Pressure Ventilation

Preoperative fasting, water deprivation, and intraoperative fluid loss and redistribution result in hypovolemia in patients undergoing surgery. Some findings have indicated that the superior vena cava (SVC) diameter and variation, as determined by transesophageal echocardiography during surgery, do not reflect central venous pressure effectively. This study aimed to compare and correlate the SVC diameter and variation with the stroke volume variation for predicting fluid responsiveness in patients undergoing invasive positive pressure ventilation.

Effect of Single Intra-cutaneous Injection for Acute Thoracic Herpes Zoster and Incidence of Postherpetic Neuralgia

Abstract The therapeutic effect of postherpetic neuralgia (PHN) is often disappointing and challenging. The role of intra‐cutaneous injection of local anesthetic and steroids in preventing PHN remains unknown. The purpose of this study was to investigate the effect of a single intra‐cutaneous injection of ropivacaine plus methylprednisolone on acute thoracic herpes zoster (HZ) pain intensity and duration, eruptive duration, and PHN incidence. A total of 97 patients with acute thoracic HZ diagnosed 1‐7 days after the onset of the rash were randomly assigned to receive either 15 mL of 37.5 mg ropivacaine plus 40 mg methylprednisolone (active group, n = 49) or 15 mL of saline (placebo group, n = 48). Over 7 days, all patients received 800 mg of acyclovir 5 times daily and 150 mg pregabalin twice daily. Acetaminophen was used as a rescue analgesia when visual analog scale ≥4. Pain intensity was measured with visual analog scale and the amount of analgesic taken was evaluated at the initial visit and at weeks 1, 4, 12, and 24 after the intra‐cutaneous injection. The time of complete resolution of pain, time of healing of skin eruption, and incidence of PHN were reported. The active group displayed a significantly shorter duration of pain (28.4 ± 46.7 vs. 59.2 ± 65.0, respectively; p = .009) and herpetic eruption (22.5 ± 6.8 vs. 32.6 ± 7.6, respectively; p < .001) than the placebo group. A significantly lower incidence of PHN was encountered in the active group after 4 weeks (16.3% vs. 47.9%, respectively; p = .001) and 12 weeks (10.2% vs. 29.2%, respectively; p = .019). Lower incidence of PHN was noticed in the active group after 24 weeks; however, this was not statistically significant (6.1% vs. 18.8%, respectively; p = .059). There was a significant reduction in the average and total doses of pregabalin and acetaminophen in the active group after the injection. No serious side effects were noticed during the study period. Early single intra‐cutaneous injection, in combination with antiviral agents and optimal analgesics, in the course of acute thoracic HZ seems to be a simple, well‐tolerated, and effective adjuvant treatment modality. It dramatically decreased pain intensity, shortened pain duration, reduced skin eruption, and reduced and may even prevent the development of PHN.

Effect of dexmedetomidine as an adjuvant to ropivacaine for wound infiltration in patients undergoing open gastrectomy: A prospective randomized controlled trial

Objectives: The primary objective of this study was to investigate whether dexmedetomidine could potentiate the analgesic efficacy of ropivacaine, when added to ropivacaine for wound infiltration in patients undergoing open gastrectomy. Methods: Fifty patients scheduled for open gastrectomy were divided into 2 equal groups that were received wound infiltration using 20 mL 0.3% ropivacaine plus 2 mL normal saline (group R) or 20 mL 0.3% ropivacaine plus 2 mL 1.0 &mgr;g/kg dexmedetomidine (group DR). Visual analogue scale (VAS) pain score, patient-controlled analgesia (PCA) pump press number, sufentanil consumption, postoperative nausea and vomiting (PONV), and wound healing score were recorded. Results: The VAS pain score were comparable between the 2 groups at the observation time points (P > .05), PCA pump press number and sufentanil consumption were higher in group R than that in group DR at 0 to 2, 2 to 4, 4 to 6 time intervals (P < .05) except for 6 to 8, 8 to 10, 10 to 12 time intervals (P > .05), meanwhile, the 24 hours total sufentanil consumption was also higher in group R than that in group DR (90.4 ± 20.5 vs 79.2 ± 9.4) (P < .05), there were no significant differences in PONV and wound healing score between the 2 groups (P > .05). Conclusions: Dexmedetomidine as an adjuvant to ropivacaine for wound infiltration promoted the analgesic efficacy of ropivacaine, reduced sufentanil consumption, and had no effect on wound healing; it could be as an ideal adjuvant which could potentiate the analgesic efficacy of local anesthetics.

Triggering Receptor Expressed on Myeloid Cells 2 Overexpression Inhibits Proinflammatory Cytokines in Lipopolysaccharide-Stimulated Microglia

Microglia play an important role in mediating inflammatory processes in the central nervous system (CNS). Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglia-specific receptor and could decrease neuropathology in Alzheimers disease (AD). However, the detailed mechanism remains unclear. This study was designed to elucidate the effect of TREM2 on microglia. We showed that lipopolysaccharide (LPS) stimulation significantly increases proinflammatory cytokines and suppressed TREM2 in microglia. In addition, TREM2 overexpression inhibited LPS-induced microglia activation and elevated M2 phenotype of microglia. Together, our results demonstrate that TREM2 overexpression reduced LPS-induced proinflammatory cytokine release in microglia and increased M2 phenotype of microglia. These findings provide novel insights that the regulation of microglia polarization may be an approach for ameliorating microglia inflammation in neurodegenerative diseases.

Effect of Repetitive Intracutaneous Injections with Local Anesthetics and Steroids for Acute Thoracic Herpes Zoster and Incidence of Postherpetic Neuralgia

Background Treatment of established postherpetic neuralgia (PHN) is difficult and often disappointing. In this study, we assessed the efficacy of repetitive intracutaneous injections with local anesthetics and steroids in acute thoracic herpes zoster (HZ) pain, herpetic eruption, and incidence of PHN. Methods Ninety-three patients with acute thoracic HZ were randomly assigned to receive a standard treatment of antiviral medication with p.o. analgesics or the standard treatment with the addition of repetitive intracutaneous injections of a local anesthetic and steroid mixture. Patients were permitted to take tramadol when the visual analog scale (VAS) ≥ 4. Pain assessment using VAS was conducted at the initial visit, as well as 1, 2, 4, 12, and 24 weeks after the end of the treatments. Results In comparison with the standard treatment group, the VAS scores of the intracutaneous injection group were significantly lower during the study. The intracutaneous injection group also reported shorter duration of pain and skin eruption than the control group ( P  = 0.005 vs P  < 0.001, respectively). At 1 month post-therapy, 12.8% patients in the intracutaneous injection group reported zoster-associated pain, compared with 47.8% in the standard treatment group ( P  < 0.001). At 3 and 6 months post-therapy, the incidence of PHN was still significantly lower in the intracutaneous injection group than the standard treatment group. EuroQol VAS scores were significantly higher in the intracutaneous injection group vs standard treatment group (P < 0.001). Conclusion Repetitive intracutaneous injections with local anesthetics and steroids along with standard treatment significantly reduce the duration of pain and herpetic eruption and incidence of PHN.