Intrathecal glutamate release during hindlimb tourniquet inflation and femoral artery occlusion in rats

Background/PurposeA tourniquet is commonly used in limb surgery. Tourniquet inflation after a period of time may produce painful sensation. While the mechanisms of tourniquet-induced pain are still unknown, two components, pressure and ischemia, have been proposed. In this study, in vivo microdialysis was used to detect changes in intrathecal glutamate, an excitatory amino acid highly relevant to pain transmission, following hindlimb tourniquet application and femoral artery occlusion in the rat.MethodsMale Wistar rats were used. For the tourniquet study, 6 rats of the study group received 30 minutes right hindlimb tourniquet inflation and another 6 rats as the control group received only tourniquet application without inflation. In the femoral artery occlusion study, 6 rats of the study group received 30 minutes right femoral artery occlusion and another 6 rats as the control group received only sham operation without femoral artery occlusion. Cerebrospinal fluid dialysates were collected prior to, during, and after tourniquet application or femoral artery occlusion. Glutamate was measured by HPLC.ResultsA significant increase in intrathecal glutamate release was found during the tourniquet inflation period, and it returned to baseline after tourniquet deflation. No change of glutamate release was noted during femoral artery occlusion or after femoral artery reperfusion.ConclusionThe intrathecal glutamate release was increased by the hindlimb tourniquet inflation, but not influenced by femoral artery occlusion in the rat

Baicalin ameliorates neuropathic pain by suppressing HDAC1 expression in the spinal cord of spinal nerveligation rats.

[[abstract]]Background/Purpose In a recent study, we found that baicalin exhibited a potent analgesic effect on carrageenan-evoked thermal hyperalgesia. The underlining mechanisms may be associated with inhibition of inflammatory mediator overproduction, including proinflammatory cytokines, nitric oxide (NO), and prostaglandin E2 (PGE2). In the present study, we examined the effect of baicalin on the antinociceptive effect of morphine and histone deacetylase 1 (HDAC1) expression in the spinal cord dorsal horn in neuropathic pain rats. Methods Neuropathic pain was induced by tight ligation of the left L5 spinal nerve of the rats. An intrathecal catheter was implanted for drug administration. Nociception was assessed by using the plantar test with the Hargreaves radiant heat apparatus, and the von Frey test with the dynamic plantar anesthesiometer. Spinal cords were removed for histone acetyl-H3 and HDAC1 western blot analysis at the end of the nociceptive assessment. Results The results showed that hyperalgesia and allodynia were observed in the spinal nerve ligated (SNL) left hindlimb; it was companied by histone-H3 deacetylation and HDAC1 overexpression on the ipsilateral side of the spinal cord dorsal horn. Intrathecal injection of baicalin (10 μg) significantly attenuated the allodynia and hyperalgesia, and enhanced the antinociceptive effect of morphine (15 μg). Moreover, baicalin reversed the histone-H3 acetylation and suppressed HDAC1 expression on the ipsilateral side of the spinal cord dorsal horn of SNL rats. Conclusion The present findings suggest that baicalin can ameliorate neuropathic pain by suppressing HDAC1 expression and preventing histone-H3 acetylation in the spinal cord dorsal horn of SNL rats

Optimal size selection of the classic laryngeal mask airway by tongue width-based method in male adults

Background: Proper size selection is crucial to the effective use of a laryngeal mask airway (LMA). The current choice of LMA size is based on body weight; in addition, the sex-based selection has also been suggested. However, the relationship between body weight, sex, and the dimension of hypopharynx where the LMA is positioned are inconsistent. Here we examined a tongue width-based method to determine the optimal size for the classic LMA (cLMA). Methods: The enrolled patients had two different cLMA size selections, determined by both weight-based formula and tongue width-based method. Twenty-one male patients were studied. For the tongue width-based method, we made four rulers of different widths that corresponded to the four different cLMAs (Nos. 2.5, 3, 4, and 5) The patient was asked to open his mouth and protrude his tongue; the optimal size of cLMA was determined by the corresponding ruler which had the same tongue width of the patient. Two insertions with different-size cLMAs were randomly performed in every patient. Five parameters — frequency of insertion attempts, the presence of cuff in the mouth, end-tidal CO2 shown on monitor, oropharyngeal leak pressure, and fiberoptic score — were measured following each cLMA insertion. Results: For all of the five measured parameters, the tongue width-based method was better than weight-based formula in determining optimal cLMA size selection. Conclusion: The tongue width-based method is a convenient and efficacious alternative for selecting an optimal cLMA size in male adults

Body temperature management during pediatric full mouth rehabilitation surgery under general anesthesia

Background/purpose: It was found that body temperature would be gradually increased during pediatric full mouth rehabilitation surgery. Although the etiology is unknown, here, we introduced an effective method to maintain normothermia during this kind of surgery. Materials and methods: Following IRB approval, the medical records of pediatric patients who received full mouth rehabilitation surgery from Jan. 2014 through Jun. 2016 were collected. All the patients included were managed by a “tent-like draping” with a forced-air warmer (Life-Air 1000, Progressive Dynamics Inc.). The temperature of the forced-air was changed from 38 °C to cool ambient temperature when the body temperature higher than 36 °C. The body temperatures (preoperative, periodic during operation, and postoperative) and the maximum body temperature changes during operation were recorded. The data was compared with the results of a previous report. Results: Total 37 patients were enrolled. The maximum temperature change during operation was 2.08 ± 0.6 °C. The incidence of body temperature higher than 37.5 °C during operation was 10.8% (4/37). Compare to the previous report in which the patients received the same operation with ordinary surgical draping, the maximum temperature change and the incidence of body temperature higher than 37.5 °C during operation were significantly lower in patients received “tent-like draping” (2.08 ± 0.64 °C vs 2.50 ± 1.17 °C, p < 0.001; and 10.8% (4/37) vs 32.4% (11/34), p < 0.05, respectively) Conclusion: The increase of body temperature during pediatric full mouth rehabilitation surgery can be effectively controlled by ambient forced-air cooling using tent-like draping. Keywords: Full mouth rehabilitation, Pediatric, Hyperthermi

Resveratrol reverses morphine-induced neuroinflammation in morphine-tolerant rats by reversal HDAC1 expression

We previously showed that subsequent intrathecal (i.t.) injection of resveratrol (30 μg) significantly reverses morphine-evoked neuroinflammation in morphine-tolerant rats. The present study examined the underlying mechanism. Methods: Male Wistar rats were implanted with two i.t. catheters, one of which was connected to a miniosmotic pump and used for morphine (15 μg/h) or saline infusion for 120 hours. To examine the effects on spinal cord expression of histone deacetylase 1 (HDAC1), the inflammatory cytokine tumor necrosis factor-α (TNF-α), and TNF receptor (TNFR) 1 and TNFR2 during tolerance induction, a tail-flick test was performed prior to infusion and after 24 hours, 48 hours, 72 hours, 96 hours, and 120 hours of infusion. Results: Resveratrol treatment prior to morphine challenge restored the antinociceptive effect of morphine in morphine-tolerant rats and reversed the morphine infusion-induced increase in HDAC1, TNF-α, and TNFR1 expression. Moreover, chronic morphine infusion increased TNFR1-specific expression in neuron in morphine-tolerant rat spinal cords, and this effect was almost completely inhibited by resveratrol treatment prior to morphine challenge. Conclusion: Resveratrol restores the antinociceptive effect of morphine by reversing morphine infusion-induced spinal cord neuroinflammation and increase in TNFR1 expression. The reversal of the morphine-induced increase in TNFR1 expression by resveratrol is partially due to reversal of the morphine infusion-induced increase in HDAC1 expression. Resveratrol pretreatment can be used as an adjuvant in clinical pain management for patients who need long-term morphine treatment or with neuropathic pain

Nonintubated video-assisted thoracoscopic surgery using regional anesthesia and targeted sedation in a myasthenia gravis patient

Myasthenia gravis (MG) is a disease affecting the acetylcholine receptor in the neuromuscular junction. Symptoms of MG are muscle weakness and fatigue. Video-assisted thoracoscopic extended thymectomy (VATS-ET) is well established in the treatment of MG if medical treatment is failed. In the recent decade, VATS under nonintubated anesthesia has been intensively researched and reported, which has been advocated to be a preferred alternative to the conventional intubated anesthesia for pulmonary nodules. However, cases with MG receiving nonintubated VATS-ET have rarely been reported. Here, we described a successful anesthesia of a 44-year-old woman with MG undergoing nonintubated VATS-ET

Effect of Epidural Neuraxial Blockade-dependent Sedation on the Ramsay Sedation Scale and the Composite Auditory Evoked Potentials Index in Surgical Intensive Care Patients

Peripheral deafferentation induced by neuraxial anesthesia reduces the degree of cortical arousal. This study investigated whether epidural analgesia blockade decreased sedation, as measured by the rapidly extracted auditory evoked potentials index, A-line autoregressive index (AAI) and Ramsay Sedation Scale (RSS) in sedated surgical intensive care patients, and looked at whether this was a concentration-dependent effect of lidocaine. Methods: Forty patients underwent major lower abdominal surgery and received epidural analgesia in the surgical intensive care unit. Patients were continuously sedated with propofol to achieve an RSS value of 3, randomly divided into two groups, and received epidural analgesia with 10 mL of 0.5% or 1% lidocaine. Sedation was evaluated using the RSS and AAI, and analgesia was evaluated using a visual analog scale (VAS). RSS, AAI, electromyography (EMG) activity of AAI and VAS values were recorded at 5 minutes before and 30, 60 and 90 minutes after epidural lidocaine administration. Results: Epidural 0.5% lidocaine produced a reduction of AAI, EMG and VAS at 30, 60 and 90 minutes after administration. For 1% epidural lidocaine administration, AAI, EMG and VAS were also reduced at 30, 60 and 90 minutes after epidural lidocaine administration. However, there was no difference in the AAI between the two concentrations; moreover, no significant change was observed in the RSS. Conclusion: Epidural lidocaine analgesia could potentiate sedation in patients evaluated by the AAI, but had no effect on the RSS. The present study suggests that the AAI could provide an objective and more precise index than the RSS in evaluation of sedation level in patients who are undergoing epidural pain management in the intensive care unit

Intravenous Dexamethasone Pretreatment Reduces Fentanyl-induced Cough

Fentanyl is regularly used in clinical anesthesia practice but fentanyl-induced cough (FIC) will sometimes bother anesthesiologists. This study was designed to examine the effect of intravenous (IV) dexamethasone (DEX) on FIC. Methods: Eighty ASA class I–II patients, aged 18-80 years and weighing 40-90 kg, scheduled for elective surgery were given DEX to reduce FIC. One hundred and eight patients from our previous study database on FIC, after excluding smokers, comprised the reference group. All patients were given fentanyl (100 μg for 40–69 kg and 150 μg for 70–90 kg for clinical convenience) over 2 seconds via the proximal port of a peripheral IV line in the forearm. Patients in the treatment group received DEX (10 mg, IV) 5 minutes prior to fentanyl injection, while those in the reference group received fentanyl injection only without any premedicant. We recorded the number of coughs of each patient for 30 seconds after fentanyl injection. Results: The incidence of cough was 6.3% in the DEX group and 21.3% in the control group, respectively (p = 0.008). However, the severity of cough observed was not significantly different by DEX pretreatment (p>0.05) or hemodynamic profiles. Conclusion: DEX (10 mg, IV) 5 minutes prior to fentanyl injection reduces the incidence of FIC and can be an ideal premedicant for general anesthesia induction

Successful nasotracheal intubation in a patient with distorted airway anatomy by combined use of flexible fiberoptic bronchoscope and trachway

Nasotracheal intubation for airway anatomy distorted patients is often frustrating. Here, we describe a redo oral cancer patient who received awake nasotracheal intubation under flexible fiberoptic bronchoscopy (FFB) guidance with assistance of the Trachway ® intubating stylet. After repeated failures of locating the epiglottis or vocal cords with the FFB, we put Trachway stylet into the oropharynx to assist identifying glottic structures. With the assistance of Trachway, glottic structures and the tip of FFB were identified, and fiberoptic intubation was achieved without complications. Therefore, this feasible application may be applied to patients with distorted airway who requires nasotracheal intubation

Ultra-low dose (+)-naloxone restores the thermal threshold of morphine tolerant rats

As known, long-term morphine infusion leads to tolerance. We previously demonstrated that both co-infusion and post-administration of ultra-low dose (±)-naloxone restores the antinociceptive effect of morphine in morphine-tolerant rats. However, whether the mechanism of the action of ultra-low dose (±)-naloxone is through opioid receptors or not. Therefore, in the present study, we further investigated the effect of ultra-low dose (+)-naloxone, it does not bind to opioid receptors, on the antinociceptive effect of morphine. Methods: Male Wistar rats were implanted with one or two intrathecal (i.t.) catheters; one catheter was connected to a mini-osmotic pump, used for morphine (15 μg/h), ultra-low dose (+)-naloxone (15 pg/h), morphine plus ultra-low dose (+)-naloxone (15 pg/h) or saline (1 μl/h) infusion for 5 days. On day 5, either ultra-low dose (+)-naloxone (15 pg) or saline (5 μl) was injected via the other catheter immediately after discontinued morphine or saline infusion. Three hours later, morphine (15 μg in 5 μl saline) or saline were given intrathecally. All rats received nociceptive tail-flick test every 30 minutes for 120 minutes after morphine challenge at different temperature (45–52°C, respective). Results: Our results showed that, both co-infusion and post-treatment of ultra-low dose (+)-naloxone with morphine preserves the antinociceptive effect of morphine. Moreover, in the post administration rats, ultra-low dose (+)-naloxone further enhances the antinociceptive effect of morphine. Conclusion: This study provides an evidence for ultra-low dose (+)-naloxone as a therapeutic adjuvant for patients who need long-term opioid administration for pain management