Tomio Andoh

Intrathecally administered Sema3A protein attenuates neuropathic pain behavior in rats with chronic constriction injury of the sciatic nerve.

Semaphorins, one of the repulsive axonal guidance factors during development, are produced under pathological conditions in adult animals. In the neuropathic pain state associated with peripheral nerve injury, synaptic reorganization occurs in spinal cord dorsal horn. In the present study, we investigated the roles of intrathecal administration of Sema3A, a secreted semaphorin, in the spinal cord of chronic constriction injury (CCI) model rat. Neuropilin 1 (NPR1) and Plexin A (PlexA), co-receptors of Sema3A, were expressed in the dorsal horn of naïve rats. NPR1, and not PlexA, protein expression increased in the dorsal spinal cord of CCI rats. Recombinant Sema3A protein attenuated mechanical allodynia and heat hyperalgesia in CCI rats, whereas heat-inactivated Sema3A had no effect. Immunohistochemistry revealed that Sema3A partially restored the decrease of isolectin B4-positive unmyelinated nerve terminals in lamina II of the ipsilateral dorsal horn of CCI rats. Contrary to our expectations, Sema3A did not change the distribution of myelinated fibers in lamina II at 7 days after CCI. Those results suggested that the suppressive role for Sema3A in the development of neuropathic pain associated with peripheral nerve injury in adult rats, which seemed to be independent from prevention of the myelinated fiber sprouting into lamina II.

Effects of sniffing position for tracheal intubation: a meta-analysis of randomized controlled trials

BACKGROUND The purpose of this meta-analysis was to validate the efficacy of the sniffing position in the performance of intubation with direct laryngoscopy. METHODS We searched MEDLINE, the Cochrane Central Register of Controlled Trials, Embase, and Web of Science. Six randomized controlled trials comprising 2759 adult participants were analyzed. The DerSimonian-Laird method was used to calculate pooled relative risk (RR) and the 95% confidence interval (CI) of Cormack-Lehane classification, Intubation Difficulty Scale, success rate of the first intubation, and weighted mean difference of intubation time. RESULTS Compared with the other head positions, the sniffing position did not improve glottic visualization, success rate of the first intubation, or intubation time. However, the sniffing position was significantly associated with better Intubation Difficulty Scale compared with the simple head extension position. (RR,1.28; 95% CI, 1.15-1.42; p<0.0001) CONCLUSIONS: Although patients do not benefit from the sniffing position in terms of glottic visualization, success rate of the first intubation, or intubation time, the sniffing position can still be recommended as the initial head position for tracheal intubation because the sniffing position provides easier intubation conditions.

Effects of erythropoietin on intracellular calcium concentration of rat primary cortical neurons.

Erythropoietin (Epo) has been shown to afford neuroprotection in many experimental models. Although the cytosolic Ca(2+) concentration ([Ca(2+)](i)) is an important factor regulating cell survival, the effects of Epo on [Ca(2+)](i) in neurons are not fully elucidated. We studied the effects of human recombinant Epo on [Ca(2+)](i) of rat primary cortical neurons in normal and excitotoxic conditions. Changes in [Ca(2+)](i) were measured using fura-2 microfluorometry in rat primary cortical cultures. In the control condition with 2mM Mg(2+) in the bath solution, Epo at 4 u/ml significantly increased the fluorescence ratio, but the Epo-induced increase in the fluorescence ratio was abolished by omission of Ca(2+) from the bath solution and by the addition of cadmium. Omission of Mg(2+) and supplementation with glycine resulted in basal and periodic increases in the fluorescence ratio, due to sustained activation of N-methyl-d-asparate (NMDA) receptors. Epo at 0.4 and 4 u/ml significantly decreased the fluorescence ratio in this condition, and this effect was attenuated by the phosphoinositide 3-kinase (PI3K) inhibitors, LY 294002 and wortmannin, and the Ca-activated K channel blocker, iberiotoxin. In the presence of Mg(2+) and exogenous glutamate, 4 but not 0.4 u/ml Epo slightly but significantly reduced the [Ca(2+)](i) elevation. These results suggest that Epo increased [Ca(2+)](i) in cortical neurons by inducing Ca(2+) entry in the control condition but decreased [Ca(2+)](i) in the Mg(2+)-free excitotoxic condition, at least in part via PI3K-dependent activation of Ca-activated K channels. Reduction of [Ca(2+)](i) by Epo in the excitotoxic condition may contribute to neuroprotection.

Effects of lubrication on air-sealing performance of a pediatric cuffed tracheal tube

BackgroundLubrication of cuffed tracheal tubes (CTTs) reduces liquid leakage. However, it is not clear how cuff lubrication influences air leakage. We aimed to test the hypothesis that pretreatment with K-Y jelly, a water-soluble lubricant, would improve the air-sealing performance of pediatric CTTs in a model study.MethodsWe placed Parker Flex-Tip™ CTT with 4.0- and 5.0-mm internal diameter (ID) into a tracheal model with 9- and 12-mm ID. The tracheal model was connected to a test lung ventilated in pressure control mode. We compared three cuff lubrication conditions: none (N), water (W), and K-Y jelly (KY). We measured the leak airway pressure (LAWP), defined as the lowest peak airway pressure (PAWP) at which leakage was detected, with the fixed cuff pressure (CP) at 20 cmH2O and varied PAWP. We also measured the leak CP (LCP), defined as the highest CP at which leakage was detected, with fixed PAWP at 25 cmH2O and varied CP. We confirmed air leakage when an apparent elevation of oxygen concentration was detected above the cuff after changing the inspiratory gas from air to oxygen.ResultsFor both 4.0-mm ID and 5.0-mm ID endotracheal tubes, the KY group showed significantly higher LAWP and lower LCP than the other two groups. For the 4.0-mm ID, median values and ranges of LAWP and LCP were K-Y group: 25 (25) and 15 (15); N group: 5 (5) and 35 (35): and W group: 5 (5) and 35 (15–35) cmH2O. For the 5.0-mm ID, median values and ranges of LAWP and LCP were K-Y group: 25 (15–25) and 15 (15–35); N group: 5 (5) and 35 (35); and W group: 5 (5) and 35 (15–35) cmH2O. Water application did not change these outcomes compared with the N group.ConclusionPre-treatment of the cuff with K-Y jelly significantly improved the air-sealing performance of a pediatric CTT in our model study.

Effect of head position on the success rate of blind intubation using intubating supraglottic airway devices

BACKGROUND To evaluate the effect of head position on the performance of intubating supraglottic airway devices, we compared the success rate of blind intubation in the head-elevated and the pillowless head positions with the LMA Fastrach and the air-Q, and the change of glottic visualization through the air-Q. METHODS We assigned 193 patients to two groups according to the device used and subgrouped by head position used for intubation: Fastrach/pillowless, Fastrach/head-elevated, air-Q/pillowless, and air-Q/head-elevated. Blind intubation through the Fastrach or the air-Q was attempted up to twice after induction of general anesthesia. Before the attempt at blind intubation with the air-Q, the percentage of glottic opening (POGO) score was also fiberscopically evaluated at the outlet of the device in both head positions in a cross-over fashion. RESULTS The Fastrach significantly facilitated blind intubation compared with the air-Q in both the pillowless and head-elevated positions: 87.2% in Fastrach/pillowless vs 65.9% in air-Q/pillowless (P=.048), 90% in Fastrach/head-elevated vs 53.7% in air-Q/head-elevated (P<.001). The head-elevated position did not significantly affect the success rate of blind intubation for either device (P=.97 in Fastrach, P=.37 in air-Q). Although the head-elevated position significantly improved the POGO score from the median (10-90 percentile) 60% (0-100%) in the pillowless position to 80% (0-100%) (P=.008), it did not contribute to successful blind intubation with the air-Q. CONCLUSION Although the head-elevated position improved glottic visualization in the air-Q, the head position had minimal influence on the success rate of blind intubation with either the Fastrach or the air-Q.

Light-emitting diode illuminant and a plastic single-use blade for intubation during cardiopulmonary resuscitation: an infant manikin study.

Although plastic single-use laryngoscope blades avoid preventable contamination that may occur in reusable metal blades [1-3], several studies have reported on their poor performance, presumably because of insufficient rigidity [4,5]. Recently, light-emitting diode (LED) light handles, providing bright and bluish-white light, became commercially available. We compared the intubation performance of plastic single-use laryngoscope blades using an LED light handle with reusable laryngoscopes in easy and difficult airways during cardiopulmonary resuscitation (CPR) in an infant manikin. Twelve certified anesthetists participated in this study. We evaluated intubation with 3 combinations of size 1 Miller-type laryngoscope blades and handles: (1) reusable metal blade (Miller halogen fiber optic blade; Welch Allyn, NY, USA) and conventional halogen light handle (Fiber optic laryngoscope standard handle; Welch Allyn) (control combination); (2) plastic single-use blade (Crystal disposable laryngoscope blade, Miller type; Penlon, Abingdon, UK) with the same halogen light handle (Plast-Hal combination); and (3) Plastic blade (same type) with an LED light handle (HEINE standard LED laryngoscope handle; HEINE, Herrshing, Germany) (Plast-LED combination). Before the study, the intensity of illumination for each combination was calibrated with a new dry-cell battery (Table 1). Intubation was performed with a 3.0-mm tracheal tube without cuff in an infant manikin (ALS baby trainer 200; Laerdal Medical Japan, Tokyo, Japan). The participating anesthetists intubated the manikins trachea with 3 combinations of laryngoscope in 2 scenarios: the control scenario and the chest compression scenario. After completing intubations in each scenario, an operator rated the subjective difficulty with each device using a 5-point intubation difficulty scale (IDS). We also defined glottic visualization as follows: class I, whole view of vocal cords; class IIa, partial view of vocal cords (more than 50%); class IIb, partial view of vocal cords (up to 50%); class III, only the epiglottis is visible; and class IV, neither the epiglottis nor the glottis is visible [6,7]. There were no significant differences in IDS or glottic visualization between the combinations in the control scenario (Figs. 1 and 2). In the chest compression scenario, the Plast-Hal combination resulted in significantly higher IDS (P = .021) and impeded glottic visualization (P = .038) in comparisonwith the control combination. There was no significant difference in IDS or glottic visualization between the other combinations (Figs. 1 and 2). Although the differences did not reach statistical significance, in both scenarios, the time to intubate was always the shortest with the conventional combination, second shortest with the Plast-LED combination, and longest with the Plast-Hal combination (Fig. 3). In the control scenario, a single-use plastic blade was comparable to a reusable metal blade in intubation performance, which was inconsistent with previous studies [4,5]. We assumed that the rigidity of a single-use plastic blade was tolerable in easy airways because laryngoscopy to visualize the glottis in an infant manikin required less force than previous studies using adult patients or manikins. Our results indicated that chest compression impeded the ease of intubation with the Plast-Hal combination. It is likely that the difficult airway associated with chest compression would require additional force during laryngoscopy. Therefore, the insufficient rigidity of a plastic single-use blade became evident, making intubation difficult with reduced glottis visualization. Interestingly, the difficulty of intubation with a plastic single-use blade improved when a LED light handle