Effects of Positive End-Expiratory Pressure on Intraocular Pressure during One-Lung Ventilation in the Lateral Decubitus Position-A Prospective Randomized Trial.

Background and Objectives: The effect of positive end-expiratory pressure (PEEP) on intraocular pressure (IOP) is debatable. There have been no studies investigating the effects of PEEP on IOP during one-lung ventilation (OLV). We aimed to investigate the effects of PEEP on IOP in patients undergoing OLV for video-assisted thoracoscopic surgery (VATs). Materials and Methods: Fifty-two patients undergoing VATs were divided into a zero-PEEP (ZEEP) and a 6 cmH2O of PEEP (PEEP) groups. IOP, ocular perfusion pressure (OPP), and respiratory and hemodynamic parameters were measured before induction (T1), immediately following endotracheal intubation (T2), 30 min (T3) and 60 min (T4) after a position change to the lateral decubitus position (LDP) and OLV, and 10 min following two-lung ventilation near the end of the surgery (T5). Results: There was no significant difference in IOP and OPP between the two groups. The IOP of the dependent eye was significantly higher than that of the non-dependent eye during LDP in both groups. Peak inspiratory pressure was significantly higher in the PEEP group than in the ZEEP group at T3-T5. Dynamic compliance was significantly higher in the PEEP group than in the ZEEP group at T2-T5. The ratio of arterial oxygen partial pressure to fractional inspired oxygen was significantly higher in the PEEP group than in the ZEEP group at T4. Conclusions: Applying 6 cmH2O of PEEP did not increase IOP but enhanced dynamic compliance and oxygenation during OLV. These results suggest that 6 cmH2O of PEEP can be safely applied during OLV in LDP.

Laminated and infused Parafilm® - paper for paper-based analytical devices.

Numerous fabrication methods have been reported for microfluidic paper-based analytical devices (µPADs) using barrier materials ranging from photoresist to wax. While these methods have been used with wide success, consistently producing small, high-resolution features using materials and methods that are compatible with solvents and surfactants remains a challenge. Two new methods are presented here for generating µPADs with well-defined, high-resolution structures compatible with solvents and surfactant-containing solutions by partially or fully fusing paper with Parafilm® followed by cutting with a CO2 laser cutter. Partial fusion leads to laminated paper (l-paper) while the complete fusion results in infused paper (i-paper). Patterned structures in l-paper were fabricated by selective removal of the paper but not the underlying Parafilm® using a benchtop CO2 laser. Under optimized conditions, a gap as small as 137 ± 22 µm could be generated. Using this approach, a miniaturized paper 384-zone plate, consisting of circular detection elements with a diameter of 1.86 mm, was fabricated in 64 × 43 mm2 area. Furthermore, these ablation-patterned substrates were confirmed to be compatible with surfactant solutions and common organic solvents (methanol, acetonitrile and dimethylformamide), which has been achieved by very few µPAD patterning techniques. Patterns in i-paper were created by completely cutting out zones of the i-paper and then fixing pre-cut paper into these openings similar to the strategy of fitting a jigsaw piece into a puzzle. Upon heating, unmodified paper was readily sealed into these openings due to partial reflow of the paraffin into the paper. This unique and simple bonding method was illustrated by two types of 3D µPADs, a push-on valve and a time-gated flow distributor, without adding adhesive layers. The free-standing jigsaw-patterned sheets showed good structural stability and solution compatibility, which provided a facile alternative method for fabricating complicated µPADs.

Variation in intraocular pressure caused by repetitive positional changes during laparoscopic colorectal surgery: a prospective, randomized, controlled study comparing propofol and desflurane anesthesia.

Laparoscopic surgery is often prolonged and requires positional changes to facilitate surgical access. Previous studies reported intraocular pressure (IOP) changes in one fixed position. This study investigated the effect of desflurane and propofol anesthesia on IOP during repeated positional changes. A total of 46 patients undergoing laparoscopic colorectal surgery were randomized into desflurane or propofol groups. IOP was measured using a handheld tonometer at seven time points: before induction (baseline), after endotracheal intubation, after pneumoperitoneum, after the first Trendelenburg and right tilt position, after reverse Trendelenburg and right tilt position, after the second Trendelenburg and right tilt position and before endotracheal extubation. Trendelenburg positioning raised IOP in both groups. In the desflurane group, IOP at the first Trendelenburg position was 6.27 and 8.48 mmHg higher than baseline IOP in left and right eye, respectively; IOP at the second Trendelenburg position was 7 and 9.44 mmHg higher than baseline in left and right eye, respectively. In the propofol group, IOP at the first Trendelenburg position was 2.04 and 4.04 mmHg higher than baseline in left and right eyes, respectively. It was 3.04 and 4.87 mmHg higher than baseline in left and right eye, respectively, at the second Trendelenburg position. In the desflurane group, 56.52% patients exhibited high IOP (≥ 25 mmHg) compared with 13.04% in the propofol group at the second Trendelenburg position in the right eyes (P = 0.005). There was a positive correlation between IOP and peak inspiratory pressure (P < 0.001). Propofol anesthesia mitigated wide variations in IOP caused by repetitive positional changes during laparoscopic colorectal surgery.

Optimal dose of prophylactic dexmedetomidine for preventing postoperative shivering.

OBJECTIVE: The aim of this study was to investigate the optimum dosage of dexmedetomidine for prevention of postanesthetic shivering. METHODS: One-hundred thirty two ASA physical status I-II patients scheduled for elective laparoscopic total hysterectomy were enrolled in this randomised, placebo-controlled study. Patients were randomly allocated to receive dexmedetomidine in four groups: group S (0.9% normal saline), group D0.5 (dexmedetomidine 0.5 µg/kg), group D0.75 (dexmedetomidine 0.75 µg/kg), group D1.0 (dexmedetomidine 1.0 µg/kg). Time to extubation and tympanic temperature during and after operation were measured. Shivering was graded (0-3 scale) upon patients arrival to the PACU and every ten minutes thereafter up to forty minutes. Sedation and first rescue analgesic time at the PACU were evaluated. RESULTS: The incidence of shivering was significantly lower in group D0.75 and D1.0 than in group S (P < 0.05). There were significantly fewer patients with a shivering score of 2 or 3 in groups D0.75 and D1.0 than in group S (P < 0.05, P < 0.001). Extubation time was shorter in group S than in groups D0.75 and D1.0 (P < 0.05). Tympanic temperature at 40 minutes postoperatively in the recovery room was higher in group S than in the other dexmedetomidine groups (P < 0.05) Fewer patients required rescue analgesia in groups D0.75 and D1.0 than in group S (P < 0.001), and the time to rescue analgesia was longer in group D1.0 than in group S (P < 0.001). Modified Observer's Assessment of Alertness/Sedation (MOAA/S) at arrival in the PACU was lower in all dexmedetomidine groups than in group S (P < 0.05). CONCLUSIONS: Our results suggest that dexmedetomidine 0.75 or 1.0 µg/kg provides effective prophylaxis against postoperative shivering as well as an analgesic effect. Though potential for intraoperative requirement for atropine, sedation in the immediate recovery period and delayed extubation time with dexmedetomidine was noted, there were no major clinical impacts on the overall recovery from anesthesia.

Material properties of the Pt electrode deposited on nafion membrane by the impregnation-reduction method.

Platinum nanoparticles (Pt NPs) were chemically deposited on a Nafion polymer electrolyte membrane by the impregnation-reduction (I-R) procedure to prepare an active electrode for solid electrochemical sensors. Various analysis methods such as SEM, EDX, XRD and cyclic voltammogram (CV) measurements were employed in order to characterize microstructures and electrochemical properties of the Pt layer. At the conditions ([Pt(NH3)4Cl2] = 10 mM, [NaBH4] = 60 mM, 50 degrees C), the porous Pt thin-film, consisting of sphere-like particles formed by the agglomeration of primary polycrystalline Pt NPs with an average crystal size of 13-18 nm, was obtained and confirmed to have a large surface area (roughness factor = 267) and strong adhesion due to the formation of interfacial Pt-Nafion composites. The secondary globular particles were found to have an average diameter of 215 nm and irregular protuberances on the surface. Furthermore, this electrode exhibited well-resolved CV peaks for the hydrogen redox reactions in an acid solution, suggesting the existence of different adsorption sites and good electrochemical behaviors. Pt/Nafion electrodes were prepared under different conditions in [Pt(NH3)4Cl2], [NaBH4] and reaction temperature, and their material properties were discussed from the viewpoint of a Pt growth mechanism.

A novel methanol sensor based on gas-penetration through a porous polypyrrole-coated polyacrylonitrile nanofiber mat.

In this work, we propose a novel chemoresistive gas sensor operated under a vertical analyte flow passing through a permeable sensing membrane. Such a configuration is different from the use of a planar sensor implemented under a conventional horizontal flow. A highly porous core-shell polyacrylonitrile-polypyrrole (PAN@PPy) nanofiber mat was prepared as the sensing element via electrospinning and two-step vapor-phase polymerization (VPP). Various analysis methods such as SEM, TEM, FT-IR and XPS measurements were employed in order to characterize structural features of the porous sensing mat. These analyses confirmed that very thin (ca. 10 nm) conductive PPy sheath layers were deposited by VPP on electrospun PAN nanofibers with an average diameter of 258 nm. Preliminary results revealed that the gas penetration-type PAN@PPy sensor had a higher sensor response and shorter detection and recovery times upon exposure to methanol analyte when compared with a conventional horizontal flow sensor due to efficient and fast analyte transfer into the sensing layer.

The effects of etomidate on expression of high mobility group box 1 via the nuclear factor kappa B pathway in rat model of sepsis.

Etomidate is an anesthetic agent used in hemodynamically unstable patients, but its use has been controversial in septic patients. The response of high-mobility group box 1 (HMGB1), a late-phase lethal cytokine in sepsis, to etomidate has not been reported. This study investigated the effects of etomidate on the expression and release of HMGB1 and the underlying mechanism using a cecal ligation and puncture (CLP) model. Thirty-six male Sprague-Dawley rats were divided into sham, CLP, and Etomi groups. Sepsis was induced in the CLP and Etomi groups, and intravenous etomidate (4 mg/kg) was infused for 40 min immediately after operation in the Etomi group. Serum creatinine, alanine aminotransferase (ALT), tumor necrosis factor (TNF)-α, interleukin (IL)-6, and HMGB1 levels were measured 6 and 24 hours after surgery. Activation of nuclear factor (NF)-ĸB and HMGB1 mRNA expression in the liver, lung, kidney, and ileum tissues were measured, and immunohistochemical staining of HMGB1 was implemented. Increases of the TNF-α level 6 h after CLP and ALT and IL-6 levels 24 h after CLP were significantly inhibited by etomidate treatment. Etomidate treatment also significantly attenuated the increase in serum HMGB1 level at 6 and 24 h after CLP and suppressed the NF-ĸB and HMGB1 mRNA in multiple organs 24 h after CLP. Immunohistochemical staining also revealed that etomidate treatment inhibited HMGB1 expression. Etomidate inhibited the systemic release of HMGB1 and its expression in various organs. The mechanism may be associated with the inhibitory effects of etomidate on pro-inflammatory cytokine release and NF-ĸB activity.

Synthesis and characterization of conductive core-shell polyacrylonitrile-polypyrrole nanofibers.

Nonwoven polyacrylonitrile-polypyrrole (PAN-PPy) core-shell nanofiber mats were prepared through the growth of PPy layers on electrospun PAN nanofibers via a two-step vapor-phase polymerization, i.e., the wet-coating of ferric tosylate (FeTos) oxidants on PAN nanofibers followed by exposure to pyrrole monomers in the gas phase. Under the conditions ([FeTos] = 10 wt%, reaction time = 15 min, temperature = 15 degrees C), the PPy polymerization procedure led to both a uniform coating over the PAN surface with an average thickness of 18 nm and cross-linkages among the nanofibers without a noticeable change in the highly porous nanofibrous structures. The oxidant concentration and polymerization time were found to be key parameters for achieving a good nanostructured core-shell fiber mat. FT-IR, XPS, XRD and conductivity measurements confirmed the synthesis of Tos-doped PPy with some degree of crystallinity and a high conductivity.

Hepatic ischemic preconditioning provides protection against distant renal ischemia and reperfusion injury in mice.

We previously demonstrated that there are acute and delayed phases of renal protection against renal ischemia and reperfusion (IR) injury with renal ischemic preconditioning (IPC). This study assessed whether hepatic IPC could also reduce distant renal IR injury through the blood stream-mediated supply of reactive oxygen species (ROS). Male C57BL/6 mice were randomly divided into four groups: group I, sham operated including right nephrectomy; group II (IR), left renal ischemia for 30 min and reperfusion injury; group III (IPC-IR), hepatic ischemia for 10 min followed by 10 min of reperfusion before left renal IR injury; group IV (MPG - IPC + IR), pretreated with 100 mg/kg N-(2-mercaptopropionyl)-glycine (MPG) 15 min before hepatic IPC and left renal IR injury. Renal function, histopathologic findings, proinflammatory cytokines, and cytoprotective proteins were evaluated 15 min or 24 hr after reperfusion. Hepatic IPC attenuated the expression of proinflammatory cytokines, tumor necrosis factor α, intercellular adhesion molecule 1, and induced inducible nitric-oxide synthase, and the phosphorylation of Akt in the murine kidney. Renal function was better preserved in mice with hepatic IPC (group III) than groups II or IV. Hepatic IPC protects against distant renal IR injury through the blood stream-delivery of hepatic IPC-induced ROS, by inducing cytoprotective proteins, and by inhibiting inflammatory reactions.

Sonochemical Preparation of a Magnet-Responsive Fe3O4@ZIF-8 Adsorbent for Efficient Cu2+ Removal.

This work presents a novel approach to synthesizing magnetic core-shell nanocomposites, consisting of magnetic nanoparticles and a metal-organic framework, for environmental applications. The synthesis is based on the encapsulation of magnetic Fe3O4 nanoparticles with microporous zeolitic imidazolate framework-8 (ZIF-8) nanocrystals via ultrasonic activation under a continuous supply of precursor solutions. This sonochemical approach is proven to be a fast, cost-effective, and controllable route for the preparation of magnet-responsive Fe3O4@ZIF-8 nanoparticles with a core-shell structure. The functional nanomaterial possesses a high content of ZIF-8 and combined micro/mesoporosity, and thus can be used as adsorbents that can be easily separated using a magnet. In particular, the sonochemically prepared Fe3O4@ZIF-8 exhibits significant adsorption performance for the removal of copper ions from water: a short adsorption time (10 min), high maximum uptake capacity (345 mg g-1), and excellent removal efficiency (95.3%). These performances are interpreted and discussed based on the materials characteristics of Fe3O4@ZIF-8 established by microscopy, gas sorption, X-ray diffraction, and thermal analysis.

Highly Hydrophobic Polydimethylsiloxane-Coated Expanded Vermiculite Sorbents for Selective Oil Removal from Water.

Naturally abundant vermiculite clay was expanded by using an aqueous solution of H2O2 and its surface was modified with ultra-thin polydimethylsiloxane (PDMS) using facile thermal vapor deposition to prepare an ecologically friendly, low-cost oil sorbent that plays an important role in oil spillage remediation. The resulting PDMS-coated expanded vermiculite (eVMT@PDMS) particles exhibited adequate hydrophobicity and oleophilicity for oil/water separation, with numerous conical slit pores (a size of 0.1-100 µm) providing a great sorption capacity and an efficient capillarity-driven flow pathway for oil collection. Simply with using a physically-packed eVMT@PDMS tube (or pouch), selective oil removals were demonstrated above and beneath the surface of the water. Furthermore, these sorbents were successfully integrated and then applied to the advanced oil-collecting devices such as a barrel-shaped oil skimmer and a self-primed oil pump.

Association of thymic stromal lymphopoietin gene -847C>T polymorphism in generalized vitiligo.

Thymic stromal lymphopoietin (TSLP) induces naïve CD4+ T cells to produce Th2 cytokines. In addition, to low production of Th2 cytokines, strong Th1 response, which plays an important role in vitiligo development, has been induced by blockade of TSLP or TSLP receptor. This study examined whether a functional TSLP polymorphism was associated with vitiligo. One hundred and sixty Korean patients with vitiligo and 568 healthy Korean individuals were examined for the four SNPs of TSLP gene. Luciferase activity was measured for promoter assay. The genotype and allele frequencies of -847C>T polymorphism were lower in vitiligo patients compared with the controls, whereas those of wild type were higher (P = 0.004, P = 0.017 respectively). None the less, the promoter activity of -847C decreased significantly (P = 0.013) compared with -847T, expecting lower TSLP mRNA levels in the polymorphism. Collectively, C allele at the TSLP -847C>T polymorphism may increase susceptibility to generalized vitiligo through decreasing TSLP mRNA expression levels.

Material and gas-sensing properties of tungsten oxide nanorod thin-films.

Tungsten oxide thin-films were deposited simply by drop-casting a solution containing single-crystalline and monodispersed W18O49 nanorods prepared by a large-scale colloidal synthesis route. They were verified to be highly porous, nonstoichiometric, and monoclinic crystal structure only with little carbon impurities. These material properties heavily reflect relevant nanostructural characteristics of the nanorods acting as a basic building block. It could be comprehended by the observed structure of randomly arranged tungsten oxide agglomerates formed by favorable parallel alignment of individual nanorod units. Tungsten oxide nanorod sensors exhibit sensitive detection capability even at room temperature to various reducing volatile organic compounds (VOCs). This anomalous performance seems to result from unique nanostructural features of the thin-films, allowing a high surface-to-volume ratio and a considerable amount of active sensing sites due to the highly anisotropic, nonstoichiometric structure of W18O49 nanorods.

Comparative study of the influence of room-temperature and warmed fluid irrigation on body temperature in arthroscopic shoulder surgery.

PURPOSE: The purpose of this study was to evaluate the effect of irrigation fluid temperature on body temperature and other variables, and to determine their correlations. METHODS: A prospective randomized study was performed of 50 patients undergoing arthroscopic shoulder surgery who received irrigation fluid either with room temperature or warmed to 37 degrees C to 39 degrees C. Core body temperature was checked at regular intervals, and additional variables, such as length of anesthesia and surgery, amount of irrigation fluid and intravenous fluid used, amount of bleeding, weight gain, and postoperative pain were collected during surgery and postoperatively. RESULTS: The final core body temperature was 35.5 +/- 0.3 degrees C in the room-temperature fluid group and 36.2 +/- 0.3 degrees C in the warmed fluid group (P < .001). The temperature drop was 0.86 +/- 0.2 degrees C in the room-temperature fluid group and 0.28 +/- 0.2 degrees C in the warmed fluid group (P < .001). Hypothermia occurred in 91.3% of patients in the room-temperature fluid group; the incidence of hypothermia was much lower in the warmed fluid group (17.4%; P < .001). Of the variables measured, the patient's age and amount of irrigation fluid used correlated with core body temperature in the room-temperature fluid group. No variables correlated with core body temperature in the warmed fluid group. CONCLUSIONS: Hypothermia occurred more often in shoulder arthroscopic surgery with room-temperature fluid irrigation than with warmed fluid irrigation. The patient's age and amount of irrigation fluid used correlate with core body temperature when using room-temperature irrigation fluid. The use of warm irrigation fluid during arthroscopic shoulder surgery decreases perioperative hypothermia, especially in elderly patients. LEVEL OF EVIDENCE: Level I, therapeutic randomized controlled trial.

Comparison of analgesic efficacy between bilateral superficial and combined (superficial and deep) cervical plexus block administered before thyroid surgery.

BACKGROUND AND OBJECTIVE: To evaluate the analgesic efficacy of bilateral superficial cervical plexus block and combined superficial and deep cervical plexus block for incision pain, headache and posterior neck pain after thyroidectomy. METHOD: Ninety patients were divided into a control group (group C, n = 30), a bilateral superficial cervical plexus group (group S, n = 30) and a bilateral combined superficial and deep cervical plexus block group (group CO, n = 30). Before general anaesthesia, we performed bilateral superficial cervical plexus block (18 ml) and combined superficial (14 ml) and deep (4 ml) cervical plexus block with 0.25% bupivacaine. Anaesthesia was maintained with propofol-remifentanil-N2O-O2. RESULTS: The average concentration of remifentanil was significantly reduced in group S compared with group C and group CO (1.1 +/- 0.3, 1.8 +/- 0.4, 1.8 +/- 0.7 ng ml, respectively; P < 0.05). The incision pain at rest and on swallowing were significantly reduced at 0, 2 and 4 h in group S compared with group C (P < 0.05). Headache showed a tendency to be reduced in group S and group CO, but the posterior neck pain was not different among the three groups. After surgery, the opioid and nonopioid requirement was significantly reduced in group S (P < 0.05). There were fewer side effects and greater patients' satisfaction in group S. CONCLUSION: Superficial cervical plexus block is a more effective technique than combined superficial and deep cervical plexus block to reduce the pain during and immediately after thyroidectomy.

Changes of intraocular pressure and ocular perfusion pressure during controlled hypotension in patients undergoing arthroscopic shoulder surgery: A prospective, randomized, controlled study comparing propofol, and desflurane anesthesia.

PURPOSE: The aim of the present study is to evaluate the effects of deliberate hypotensive anesthesia on intraocular pressure (IOP) and ocular perfusion pressure (OPP) and compare the effects of propofol total intravenous anesthesia (TIVA) and desflurane anesthesia on IOP and OPP. METHODS: A total of 50 patients undergoing arthroscopic shoulder surgery in the lateral decubitus position were randomized to receive desflurane or propofol anesthesia. Mean arterial pressure (MAP) was maintained in the range of 60-75 mm Hg during hypotensive anesthesia. IOP was measured using a handheld tonometer at 7 time points: before induction (T1, baseline); immediately after endotracheal intubation (T2); 10 minutes after position change to lateral decubitus (T3); 10, 30, and 50 minutes after the start of hypotensive anesthesia (T4-T6); and at the end of surgery (T7). RESULTS: MAP decreased about 35% to 38% during hypotensive anesthesia. Compared to baseline values, the IOP at T6 in dependent and non-dependent eyes decreased by 0.43 and 2.74 mm Hg, respectively in desflurane group; 3.61 and 6.05 mm Hg, respectively in the propofol group. IOP of both eyes in the propofol group was significantly lower than in the desflurane group from T2 to T7. OPP of both eyes in both groups was significantly lower than at baseline, except at T2 in the desflurane group. OPP of both eyes in the propofol group was significantly higher than that in the desflurane group at T5 and T6. CONCLUSIONS: Hypotensive anesthesia reduced IOP and OPP, but propofol TIVA maintained higher OPP than desflurane anesthesia. These findings suggest that propofol TIVA can help mitigate the decrease of OPP during hypotensive anesthesia.

Amitriptyline inhibits the MAPK/ERK and CREB pathways and proinflammatory cytokines through A3AR activation in rat neuropathic pain models.

BACKGROUND: The pain-relief properties of tricyclic antidepressants can be attributed to several actions. Recent observations suggest that adenosine is involved in the antinociceptive effect of amitriptyline. The A3 adenosine receptor (A3AR) is the only adenosine subtype overexpressed in inflammatory and cancer cells. This study was performed to investigate the role of A3AR in the anti-nociceptive effect of amitriptyline. METHODS: Spinal nerve-ligated neuropathic pain was induced by ligating the L5 and L6 spinal nerves of male Sprague-Dawley rats. The neuropathic rats were randomly assigned to one of the following three groups (8 per group): a neuropathic pain with normal saline group, a neuropathic pain with amitriptyline group, and a neuropathic pain with amitriptyline and 3-ethyl-5-benzyl- 2-methyl-4-phenylethynyl-6-phenyl-1,4-(±)-dihydropyridine-3,5-dicarboxylate (MRS) group. Amitriptyline or saline was administered intraperitoneally and 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(±)-dihydropyridine-3,5-dicarboxylate (MRS-1191), an A3AR antagonist, was injected subcutaneously immediately before amitriptyline administration. The level of extracellular signal-regulated kinase P44/42 (ERK1/2), cyclic AMP response element-binding protein (CREB), and proinflammatory cytokines were assessed using immunoblotting or reverse-transciption polymerase chain reaction. RESULTS: Amitriptyline increased the mechanical withdrawal threshold of the neuropathic rats. The level of phospho-ERK1/2 and phospho-CREB proteins, and proinflammatory cytokines produced by spinal nerve ligation were significantly reduced by amitriptyline administration. However, the use of MRS-1191 before amitriptyline administration not only reduced the threshold of mechanical allodynia, but also increased the signaling protein and proinflammatory cytokine levels, which were reduced by amitriptyline. CONCLUSIONS: The results of this study suggest that the anti-nociceptive effect of amitriptyline involves the suppression of ERK1/2 and CREB signaling proteins, and A3AR activation also affects the alleviation of the inflammatory response.

Optimal dose of perineural dexmedetomidine for interscalene brachial plexus block to control postoperative pain in patients undergoing arthroscopic shoulder surgery: A prospective, double-blind, randomized controlled study.

BACKGROUND: Adjuvant perineural dexmedetomidine can be used to prolong the analgesic effect of interscalene brachial plexus block (ISB). We investigated the optimal dose of dexmedetomidine in ISB for postoperative analgesia in patients undergoing arthroscopic shoulder surgery. METHODS: One hundred patients scheduled for elective shoulder arthroscopic surgery were enrolled in this randomized, double-blind study. Ultrasound-guided ISB was performed before general anesthesia using 22 mL of ropivacaine 0.5% combined with 1, 1.5, or 2 µg/kg of dexmedetomidine (group D1, D2, and D3, respectively) or with normal saline as a control (group R, n = 25 per group). The primary outcome was the duration of analgesia (DOA), numeric pain rating scale (NRS), and consumption of additional analgesics during 36 h after ISB. Secondary outcome included durations of motor and sensory block (DOM and DOS), hemodynamic variables and sedation and dyspnea scores. RESULTS: Ninety-seven patients completed the study. The DOS, DOM, and DOA were significantly longer in the dexmedetomidine groups than in group R. The DOA was significantly longer in group D3 than in groups D1 (P = .026) and D2 (P = .039). The DOA was 808.13 ±â€Š179.97, 1032.60 ±â€Š288.14, 1042.04 ±â€Š188.13, and 1223.96 ±â€Š238.06 min in groups R, D1, D2, and D3, respectively. The NRS score was significantly higher in group R than in the dexmedetomidine groups 12 h after ISB (P < .001) and significantly lower in group D3 than in the other groups 18 h after ISB (P = .02). The incidence of hypotension was higher in groups D2 and D3 than in group R during surgery (P = .008 and P = .011, respectively). There were no significant differences in consumption of rescue analgesics, sedation, and dyspnea scores between the study groups. CONCLUSION: Perineural dexmedetomidine 2 µg/kg could be the optimal dose in ISB for arthroscopic shoulder surgery in that it provides an adequate DOA. However, this dose was associated with increased risk of hypotension.

An iridium oxide reference electrode for use in microfabricated biosensors and biochips.

In this paper we argue for the use of iridium oxide (IrO(x)) electrodes as quasi-reference electrodes in microfabricated biosensors and biochips that operate in buffered solutions. The simple microfabrication of these electrodes consists of a one-step electrodeposition of IrO(x) onto a microfabricated platinum (Pt) electrode. The IrO(x) electrode potential was found to vary less than 20 mV over 9 days after stabilization for 1 day in a phosphate-buffered saline (PBS) solution; this behavior of the electrode potential was found to be easily reproduced. Moreover, the electrode potential was found to vary by less than 15 mV in the initial hour of its use; this behavior of the electrode potential was also found to be reproducible. The performance of a microfabricated glucose sensor employing an IrO(x) reference electrode is characterized in this paper in order to evaluate the usefulness of this new IrO(x) electrode as a quasi-reference electrode. The glucose sensor consists of a recessed microfabricated Pt electrode array, an electrodeposited IrO(x) film, an inner layer composed of an electropolymerized poly(m-phenylenediamine)/glucose oxidase (PMPD/GOx) film, and an outer or protective layer composed of Teflon and polyurethane (PU) films. The response of this sensor was found to be equivalent to the response of the same sensor employing a commercial Ag/AgCl reference electrode. These results show that a microfabricated IrO(x) electrode can be used as a quasi-reference electrode in microfabricated biosensors and biochips operating in buffered solutions.