Simultaneous on-line monitoring of propofol and sevoflurane in balanced anesthesia by direct resistive heating gas chromatography.

In balanced anesthesia, sevoflurane and propofol are often used in combination to achieve a better anesthetic effect. However, methods for on-line monitoring of concentrations of the two anesthetics in patients are still rare in clinical. This study proposed a non-invasive method utilizing a fast gas chromatograph combined with a surface acoustic wave sensor (Fast GC-SAW) to simultaneously on-line monitor sevoflurane and propofol in patients' exhaled gas. By using the direct resistive heating capillary column, the single detection time of Fast GC-SAW system was significantly shortened to 90s, as well as the size reduced to (40cm×30cm×20cm). Besides, in the calibration of sevoflurane, Fast GC-SAW system showed a good linear correlation (R2=0.9925, P<0.01) with gas chromatography-mass spectrometer (GC-MS), which ensured the reliability and accuracy of the Fast GC-SAW system. Finally, clinical experiments on patients under balanced anesthesia were conducted. The varied concentrations measured by Fast GC-SAW extraordinarily matched the clinical usages of these two anesthetics.

Soft catheters reduce the risk of intravascular cannulation during epidural block--a retrospective analysis of 1,117 cases in a medical center.

A wet or bloody tap is an inevitable complication while performing epidural block. The influence of different catheters on the incidence of intravascular cannulation during epidural catheterization has not been reported. We observed an initial, relatively different incidence of intravascular cannulation during the placement of different sorts of epidural catheter; hence, a retrospective review was conducted to explore the possible association. We reviewed 1-year interval anesthetic records of 1117 patients who had undergone epidural anesthesia or received patient-controlled epidural analgesia. Epidural catheter placement was performed by a loss of resistance technique with an 18-G Tuohy needle in lateral position. Patients were divided into two groups according to the different types of epidural catheters used (Perifix One, n=590; Perifix Standard, n=527). Primary outcome measurement was the incidence of intravascular injection. Other analyzed outcomes included dura puncture, failure rate, and low back pain. The incidence of epiduralintravascular cannulation was significantly lower using the Perifix One catheter (1.5%; 9/590) than using the Perifix Standard (4.6%; 24/527), p=0.003. The dura puncture rate did not differ significantly between the Perifix One (1.9%; 11/590) and the Perifix Standard (2.5%; 13/527), p=0.49. Failure rates and low back pain incidence were also comparable between the two groups. Application of the soft epidural catheter (Perifix One) may reduce the incidence of epidural intravascular cannulation. We suggest the use of Perifix One catheter instead of Perifix Standard catheter in daily practice.

Intrathecal lidocaine pretreatment attenuates immediate neuropathic pain by modulating Nav1.3 expression and decreasing spinal microglial activation.

BACKGROUND: Intrathecal lidocaine reverses tactile allodynia after nerve injury, but whether neuropathic pain is attenuated by intrathecal lidocaine pretreatment is uncertain. METHODS: Sixty six adult male Sprague-Dawley rats were divided into three treatment groups: (1) sham (Group S), which underwent removal of the L6 transverse process; (2) ligated (Group L), which underwent left L5 spinal nerve ligation (SNL); and (3) pretreated (Group P), which underwent L5 SNL and was pretreated with intrathecal 2% lidocaine (50 µl). Neuropathic pain was assessed based on behavioral responses to thermal and mechanical stimuli. Expression of sodium channels (Nav1.3 and Nav1.8) in injured dorsal root ganglia and microglial proliferation/activation in the spinal cord were measured on post-operative days 3 (POD3) and 7 (POD7). RESULTS: Group L presented abnormal behavioral responses indicative of mechanical allodynia and thermal hyperalgesia, exhibited up-regulation of Nav1.3 and down-regulation of Nav1.8, and showed increased microglial activation. Compared with ligation only, pretreatment with intrathecal lidocaine before nerve injury (Group P), as measured on POD3, palliated both mechanical allodynia (p < 0.01) and thermal hyperalgesia (p < 0.001), attenuated Nav1.3 up-regulation (p = 0.003), and mitigated spinal microglial activation (p = 0.026) by inhibiting phosphorylation (activation) of p38 MAP kinase (p = 0.034). p38 activation was also suppressed on POD7 (p = 0.002). CONCLUSIONS: Intrathecal lidocaine prior to SNL blunts the response to noxious stimuli by attenuating Nav1.3 up-regulation and suppressing activation of spinal microglia. Although its effects are limited to 3 days, intrathecal lidocaine pretreatment can alleviate acute SNL-induced neuropathic pain.

Electromyographic endotracheal tube placement during thyroid surgery in neuromonitoring of recurrent laryngeal nerve.

Intraoperative neuromonitoring (IONM) is widely used in thyroid surgery. This study aimed to investigate the influence of neck extension on electromyographic (EMG) endotracheal tube displacement and to determine the necessity of routinely checking the final electrode position after the patient had been fully positioned. A consecutive 220 patients undergoing thyroidectomy were enrolled. All patients were intubated with the EMG endotracheal tube under direct laryngoscopy. The electrode position and tube displacement were routinely checked and measured by laryngofiberoscopy before and after patient positioning. The patients were divided into two groups. In Group I (n=110), the EMG tube was taped and fixed to the right mouth angle before full neck extension. In Group II (n=110), the EMG tube was disconnected from the circuit tube and was not taped until full neck extension. In all patients, we ensured that the final electrode position was the optimal position with laryngofiberoscopic examination. The tube displacement after neck extension ranged from 16 mm upward to 4 mm downward in Group I and from 12 mm upward to 5 mm downward in Group II. The rate of tube displacement greater than 10 mm was 12.7% in Group I and 3.6% in Group II. Successful monitoring was achieved in all patients after the final optimal position of electrodes was ensured routinely. The electrode position can be severely displaced after the patient has been fully positioned. Verification of ideal position of electrodes before the beginning of the operation is a necessary step to guarantee functional intraoperative neuromonitoring.

A comparative study between 1 and 2 effective doses of rocuronium for intraoperative neuromonitoring during thyroid surgery.

BACKGROUND: The goal of this study was to explore an ideal application of rocuronium to enable adequate muscle relaxation for intubation without significantly affecting the evoked potentials measured by intraoperative neuromonitoring during thyroid surgery. METHODS: A total of 80 patients were randomized to receive 1 (group 1, n = 40) or 2 (group 2, n = 40) effective doses (ED(95)) of rocuronium to facilitate electromyographic (EMG) endotracheal tube insertion. Evoked potentials were obtained every 5 minutes by stimulating the vagus nerve between the time period of 30 and 70 minutes after administration of rocuronium. The magnitude of evoked potentials at each time point and the tracheal intubating conditions were compared between groups. Accelerometry (twitch [% TW]) was used to monitor the quantitative degree of neuromuscular transmission at the adductor pollicis muscle. RESULTS: At 30 minutes after administration of rocuronium, the rate of positive EMG response was 100% (40/40) in group 1 and 53% (21/40) in group 2 (P < .001). Positive EMG signals were obtained for all patients in group 2 until 55 minutes after administration of rocuronium. The mean amplitude detected from the time point of 30 to 60 minutes was greater in group 1 than in group 2 (P < .01). The time to tracheal intubation was 208 ± 59 seconds in group 1 and 114 ± 26 seconds in group 2 (P < .001). The overall intubating conditions were better in group 2 than in group 1 patients (P < .001). CONCLUSION: A total of 1 ED(95) of rocuronium (0.3 mg/kg) is an optimal dose for intraoperative neuromonitoring during thyroid surgery. Positive and high EMG signals were obtained in all patients at an early stage of operation, and satisfactory intubating conditions were achieved in most patients.

[Homer protein expression after focal brain contusion in rats].

OBJECTIVE: To investigate Homer protein expression after focal brain contusion and explore the relationship between expression and injury time. METHODS: Focal brain contusion in rats was established and Homer protein expression in brain at different injury intervals after contusion was detected by immunohistochemistry and Western blotting. RESULTS: A small amount of Homer positive expression cells were detected in control group, sham operated group and experimental group (0.5 h after contusion). The amount of Homer positive expression cells increased after 3 h and reached peak 12 h after contusion. The amount of positive cells continued to decrease 1 d after contusion and to the base level 7 d after contusion. Homer protein expression based on immunohistochemistry and Western blotting had statistical difference among adjacent groups. CONCLUSION: Expression of Homer protein near the focal contusion area shows time dependence after brain contusion in rats.

Equal volumes of undiluted nalbuphine and lidocaine and normal diluted saline prevents nalbuphine-induced injection pain.

OBJECTIVES: To determine if the intravenous co-administration of equal volumes of lidocaine and nalbuphine, with undiluted normal saline, prevents injection pain caused by nalbuphine. METHODS: Eighty adult patients who were scheduled for minor surgeries under general anesthesia delivered via a laryngeal mask airway (LMA) were enrolled in this prospective, randomized, single-blind clinical trial. In the saline group (control) (n = 40), 1 mL (10 mg) nalbuphine was diluted with 9 mL normal saline. In the lidocaine group (experimental) (n = 40), 1 mL (10 mg) nalbuphine was diluted with 1 mL lidocaine (20 mg). The two respective nalbuphine solutions were injected into the cephalic vein at a rate of 20 mL/minute (0.33 mL/second). Pain scores were categorized into five grades. Pain responses upon intravenous injection of nalbuphine, site of cannulation, size of the catheter, and hemodynamic responses to nalbuphine were also recorded. RESULTS: Overall, the median pain score of patients in the lidocaine group was lower than that of the saline group (p < 0.001). In addition, the incidence of injection pain was lower in the lidocaine group than the saline group (2.5% vs. 30%, p = 0.001). CONCLUSION: A solution of equal volumes of lidocaine and nalbuphine can decrease intravenous nalbuphine-induced injection pain.

Intravenous thiamylal and local anesthetic infiltration for pediatric facial repair procedures performed in emergency departments.

Thiamylal is widely used for procedural sedation in emergency departments (ED); however, there are limited safety data for doses of thiamylal > 5 mg/kg in children. We investigated whether intravenous thiamylal in combination with local anesthetics is safe and effective for pediatric procedural sedation in the ED and to identify the association between increasing doses thiamylal and adverse events. Between July 2004 and June 2008, 227 children who underwent procedural sedation met the inclusion criteria, including 105 males (46.3%) and 122 females (53.7%). Facial laceration was the most common indication for procedural sedation. All children received an intravenous injection of thiamylal, with a loading dose of 5 mg/kg. Eighty-one children (35.7%) received a supplemental dose of 2.5 mg/kg thiamylal because of inadequate sedation. Of these, 27 (11.9%) received a second supplemental dose of 2.5 mg/kg because of inadequate sedation. Sixty-six patients (29.1%) experienced 75 mild and self-resolving adverse events, and most of which (15/75; 20%) were drowsiness. Four (1.8%) patients experienced oxygen saturation below 96%, which was related to the supplemental dose of thiamylal (p = 0.002). No children suffered from any lasting or potentially serious complications. Our results indicate that intravenous thiamylal in combination with local anesthetic infiltration is a well tolerated for therapeutic procedures in the ED. Thiamylal offers rapid onset of sedation without compromising the patient's cardiorespiratory function during pediatric procedural sedation.

Application of a double-lumen tube for one-lung ventilation in patients with anticipated difficult airway.

One-lung ventilation (OLV) is essential in some surgical situations. The use of double- lumen tubes (DLTs) can achieve OLV more quickly and more easily than bronchial blockers. The management of a difficult airway is a challenge for anesthesiologists when, at the same time, OLV is needed for a surgical procedure. This report describes the successful application of DLTs in two patients with difficult airways, and who were scheduled for pulmonary decortication. Case 1 already had a permanent tracheostomy, while Case 2 had oral cancer with an extremely limited mouth opening and needed elective tracheostomy for anesthesia. Nasal intubation of Case 2 was done with fiberoptic-guided intubation with the patient awake. OLV was achieved uneventfully after inserting the DLT directly through the tracheostomy in both cases. We also describe the appropriate use of airway devices for OLV, focusing on patients with an anticipated difficult airway.

The effectiveness of dexmedetomidine infusion for sedating oral cancer patients undergoing awake fibreoptic nasal intubation.

BACKGROUND AND OBJECTIVE: Dexmedetomidine is characterized with effects of sedation, analgesia, amnesia and lack of respiratory depression. Hence, it should be suitable for awake fibreoptic intubation (AFOI). METHODS: We enrolled 30 oral cancer patients with limited mouth openings who were undergoing AFOI for elective surgery. Patients were randomly allocated into two groups; the Dex group (n = 16) that received dexmedetomidine (1.0 microg kg(-1)) infusion and the Control group (n = 14) that received fentanyl (1.0 microg kg(-1)) infusion. Main outcomes were evaluated by grading scores presenting conditions for nasal intubation and postintubation. Other analysed parameters included airway obstruction, haemodynamic changes, consumption time for intubation, amnesia level and satisfaction. RESULTS: Intubation score (1-5) representing condition for nasal intubation was significantly better in the Dex group [2(1-3)] than in the Control group [3(2-5)] (P = 0.001). Postintubation score (1-3) representing tolerance to intubation also showed more favourable results in the Dex group [1(1-3)] than in the Control group [2(2-3)] (P = 0.002). The Dex group showed significantly reduced haemodynamic response to intubation than the Control group. Incidence requiring temporary haemodynamic support was higher in the Dex group but not of significance. Both levels of amnesia and satisfaction score were significant in the Dex group. Other analysed parameters such as consumption time for intubation, airway obstruction score and postoperative adverse events did not differ significantly. CONCLUSION: Combination of dexmedetomidine loading with topical anaesthesia provides significant benefit for AFOI in intubation condition, patient tolerance, haemodynamic response, amnesia and satisfaction. Dexmedetomidine is effective for AFOI in anticipated difficult airway with only minor and temporary haemodynamic adverse effects.

[Expression of matrix metalloproteinase-3 after brain contusion in rats].

OBJECTIVE: To investigate the expression of matrix metalloproteinase-3 after brain contusion and its applicability for estimating the age of brain contusion. METHODS: Rats had been divided into three groups: control group, sham operation group and brain contusion group. The expression of matrix metalloproteinase-3 at different time was detected by immunohistochemistry and Western blot. RESULTS: By the immunohistochemistry, no staining was observed in control and sham operation groups. The positive staining of MMP-3 appeared 6 hours after contusion, increased gradually in 24 hours and peaked 5 days after contusion, then started to decrease, 14 days after contusion still could be observed. By the Western blot analysis, no expression of MMP-3 was detected in control and sham groups. The positive staining of MMP-3 appeared 6 hours after contusion, increased gradually and maximized 5 days after contusion, then started to decrease, 14 days after contusion still could be found. CONCLUSION: Time-order expression of MMP-3 could be used for estimating the age of brain contusion in forensic pathology.

Study on changes of MMP-3 expression after brain contusion in rats.

To investigate the mechanism and to explore the applicability of MMP-3 (matrix metalloproteinase-3) to determine the age of brain contusion, expression of MMP-3 was studied by immunochemistry and Western blot techniques on model of brain contusion in rats. Brain contusion was performed by falling weight in adult male Sprague-Dawley rats after anesthetized with diethyl ether, then maintained with 2% pentobarbital sodium (30 mg/kg). Samples were collected at 6 and 12 h, 1, 3, 5, 7, 10 and 14 days after the contusion. Histopathological examination and immunostaining of MMP-3 were conducted using paraffin sections. Protein of MMP-3 bands was visualized by ECL kit in Western blot. Result showed that: No staining in control and sham operation group. The staining of MMP-3 positive appeared 6 h after contusion, and it becomes stronger 24 h after contusion, the staining reached the maximum at 5 days post-contusion, then it decrease, positive staining could still be observed at 14 days after contusion. No MMP-3 expression was detected in control and sham group by Western blot analysis. Brain contusion caused the appearance of a band of 45 ku molecular weight, which corresponds to an active form of MMP-3. Conclusions were drew that there is no expression of MMP-3 in normal brain, that the expression of MMP-3 appears 6h after TBI, and that there is a relationship between the expression of MMP-3 and the time course after TBI, and MMP-3 would be used as an indicator for estimating the age of traumatic brain contusion in forensic pathology.

Observation of time correlation function of multimode two-photon pairs on a rubidium D2 line.

We report on the generation of a type-I multimode two-photon state on a rubidium D(2) line (780 nm) using periodically poled KTiOPO(4) crystals. With a degenerate optical parametric oscillator far below threshold, we observe an oscillatory correlation function; the cross correlation between two photons shows a cavity bandwidth of about 7.8 MHz. We also use a Fabry-Perot etalon to filter its most longitudinal modes and observe its time correlation function. The experimental data are well fitted to theoretical curves. This system could be utilized for demonstrating storage and retrieval of narrow-band photons in Rb atomic ensembles, which is important for long-distance quantum communication.

Optimizing proliferation and characterization of multipotent stem cells from porcine adipose tissue.

Porcine mesenchymal stem cells have been isolated previously from bone marrow but not from adipose tissue. In the present study a new cell-culture method, using a low-calcium medium supplemented with N-acetyl-L-cysteine and L-ascorbic acid 2-phosphate (the PM2 medium) was developed to grow pASCs (porcine adipose-tissue-derived stem cells). The pASCs developed using the new medium showed a high growth rate and a high proliferation potential, as measured by a cumulative population doubling level (55) that was significantly higher than those reported for ASCs in the literature. These pASCs lacked gap-junctional intercellular communication and were capable of differentiation into three mesodermal lineages (i.e. adipocytes, osteoblasts and chondrocytes) and an ectodermal lineage (i.e. neural cells). Surprisingly, osteogenic ability, but not adipogenesis, was found to increase dramatically with increasing passages. The high proliferative and differentiation potential of these pASCs should facilitate the development of a large-animal model to study the use of ASCs in regenerative and reparative medicine.

Ultrasonographic examination to search out the optimal upper arm position for coracoid approach to infraclavicular brachial plexus block--a volunteer study.

BACKGROUND: Infraclavicular brachial plexus block has been widely used for surgical procedures below the mid humerus owing to its excellent anesthetic quality and ease of practice. However, what is the optimal upper arm position for carrying out the procedure still lacks consensus of opinion. The primary goal of this study was to determine the optimal upper arm position for coracoid infraclavicular block by ultrasonographic examination. METHODS: High-frequency (5-10 MHz) ultrasonographic examination on the vertical line 2 cm medial to the coracoid process was performed in 40 volunteers. We assessed the influence of four different upper arm positions on the topographic anatomy of the infraclavicular region. Ultrasonography-derived distances and morphometric measurements were applied to evaluate the optimal puncture site. The deviation of coracoid puncture site from the ultrasonographically modified ideal puncture site in distance was also recorded. RESULTS: When the upper arm was abducted 900, the brachial plexus was much closer to the skin (1.67 cm) and farther from the pleura (1.15 cm) as compared with other positions. In this position, the revealation of anterosuperior plexus relative to artery, identification of all three cords and pleura were 53.8%, 64.1% and 87.2%, respectively. We also found that as the upper arm was drawing from abduction to adduction the ideal puncture site tended to shift more inferiorly. CONCLUSIONS: We recommend the most optimal position for carrying out coracoid infraclavicular brachial plexus block is to abduct the upper arm 90 degrees with external rotation of the shoulder. Though ultrasonographic guidance is suggested for infraclaricular brachial plexus block, an optimal position for puncture site determined by anatomical landmark is also acceptable.

Lateral rotation of the lower extremity increases the distance between the femoral nerve and femoral artery: an ultrasonographic study.

Femoral nerve block (FNB) is by far the most useful lower extremity regional anesthetic technique for the anesthesiologist, and high-resolution ultrasonography is a useful tool with which to guide the performance of FNB. However, the relationships between the femoral nerve and the femoral artery in different lower extremity positions have rarely been discussed. The purpose of this study was to evaluate the relative positions of the femoral nerve and artery at different lateral rotational angles of the lower extremities using ultrasonographic imaging. We enrolled 41 healthy volunteers in this study. Two-dimensional ultrasonographic images of the femoral nerve were obtained using an ultrasound unit, in the inguinal crease, for four positions of the bilateral lower extremities: 0 degrees , 15 degrees , 30 degrees and 45 degrees lateral rotation of each extremity. The following assessments were made in each position: minimal skin-to-nerve distance (SN) and deviation of nerve-to-landmark (femoral artery pulsation) horizontal distance (NF). A trend towards lateral rotation of both lower extremities was identified. The Pearson correlation values between rotational degree to SN and rotational degree to NF were -0.216 and 0.430, with p values of 0.001 and less than 0.001, respectively. Body mass index had a good correlation ( r = 0.76-0.78) with SN. The results of our ultrasound study revealed that the more lateral the rotation of both lower extremities, the closer the femoral nerve was to the skin and the farther away it was from the femoral artery. In order to increase the success rate and decrease the rate of complications, a suggested lateral 45 rotation of both lower extremities is strongly recommended when performing FNB using the peripheral nerve stimulator technique or the field block technique. In any situation, individual ultrasound guidance is recommended for FNB whenever possible.

Spinal process landmark as a predicting factor for difficult epidural block: a prospective study in Taiwanese patients.

Although epidural anesthesia is a common practice in neuraxial blockade, difficult access to the epidural space is a frequent problem in operating theaters. We designed this study of epidural blocks to determine if the spinal landmark grading system is valuable in predicting a difficult epidural block. Before the epidural block, we collected the following data: demographics, body habitus (normal, thin, obese, pregnant), spinal anatomy (normal, deformed), spinal level (lumbar, thoracic), and spinal landmark grade (grade 1: spinous processes visible; grade 2: spinous processes not seen but easily palpated; grade 3: spinous processes not seen and not palpated but the interval between them is palpated as a low landmark under the thumb; grade 4: other). We performed all 848 epidural blocks initially using a midline approach and an 18-gauge Touhy needle. We evaluated the technical difficulty of the epidural block using three methods: whether the epidural block was accomplished at the spinal level (first-level success); the total number of attempts at skin puncture (attempts-S); and total number of attempts to change ligament puncture direction (attempts-L) required to complete the epidural block. Of all examined factors, spinal landmark grade correlated best with technical difficulty as measured by all three methods. Deformed spinal anatomy and body habitus both correlated with difficulty, merely from the total numbers of attempts (attempts-S and attempts-L). Thoracic epidurals were more difficult than lumbar epidurals by all three measures of difficulty. We concluded that this spinal landmark grading system is valuable in predicting a difficult epidural block and advocate its use as a predictor by anesthesiologists.