Shinji Kurata

Nagasaki University Hospital, Nagasaki, Nagasaki, Japan

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Publications (23)28.87 Total impact

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    ABSTRACT: To test the hypothesis that the jaw closure using a pneumatic actuator device affect airway collapsibility and resistance during propofol anesthesia.
    No preview · Article · Mar 2016

  • No preview · Article · Jan 2016
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    ABSTRACT: The reduction of endogenous nitric oxide (NO) production during hepatic ischemia-reperfusion injury, generally via a reduction in endothelial NO synthase activity, leads to liver injury. We hypothesized that administration of an exogenous NO donor into the portal vein may ameliorate hepatic blood flow reduction after a period of ischemia. A total of 90 min of ischemia (portal vein and hepatic artery) was applied in 15 anesthetized pigs, using the Pringle method under sevoflurane anesthesia. All animals were administered either saline (control group, n = 8) or sodium nitroprusside (SNP, n = 7) as exogenous NO donor drugs into the portal vein, 30 min before and after ischemia. The portal venous blood flow and hepatic artery blood flow were measured continuously using transonic flow probes attached to each vessel. Endogenous NO (NOx = NO2- + NO3-) production was measured every 10 min using a microdialysis probe placed in the left lobe of the liver. In the SNP group, portal venous flow remained unchanged and hepatic artery flow significantly increased compared to baseline. Although the production of liver tissue NOx transiently decreased to 60% after ischemia, its level in the SNP group remained higher than the control saline group. Regional administration of SNP into the portal vein increases hepatic arterial flow during ischemia reperfusion periods without altering mean systemic arterial pressure. We speculate that administration of an exogenous NO donor may be effective in preventing liver injury via preservation of total hepatic blood flow.
    No preview · Article · Aug 2015 · Journal of Investigative Surgery
  • Terumi Ayuse · Shinji Kurata · Takao Ayuse
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    ABSTRACT: We experienced a case of life-threatening hypotension and bronchoconstriction associated with edema in a patient undergoing resection of a tumor of the right mandible following intravenous midazolam for induction of general anesthesia. We decided to postpone surgery for further examination of a possible drug-induced allergic reaction, and we rescheduled surgery for 1 week later. After administering H1 and H2 histamine antagonists, we administered a slow induction with sevoflurane in nitrous oxide and oxygen plus intravenous atropine sulfate after performing a test dose injection. We safely induced and maintained anesthesia with nitrous oxide, oxygen, and sevoflurane.
    No preview · Article · Jun 2015 · Anesthesia Progress
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    Preview · Article · Jan 2015
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    ABSTRACT: Abstract Mask ventilation, along with tracheal intubation, is one of the most basic skills for managing an airway during anesthesia. Facial anomalies are a common cause of difficult mask ventilation, although numerous other factors have been reported. The long and narrow mandible is a commonly encountered mandibular anomaly. In patients with a long and narrow mandible, the gaps between the corners of the mouth and the lower corners of the mask are likely to prevent an adequate seal and a gas leak may occur. When we administer general anesthesia for these patients, we sometimes try to seal the airway using several sizes and shapes of commercially available face masks. We have found that the management of the airway for patients with certain facial anomalies may be accomplished by attaching a mask upside down.
    No preview · Article · Dec 2014 · Anesthesia Progress
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    ABSTRACT: Although hyperventilation syndrome generally carries a good prognosis, it is associated with the risk of developing severe symptoms, such as post-hyperventilation apnea with hypoxemia and loss of consciousness. We experienced a patient who suffered from post-hyperventilation apnea. A 17-year-old female who suffered from hyperventilation syndrome for several years developed post-hyperventilation apnea after treatment using the paper bag rebreathing method and sedative administration during a dental procedure. We subsequently successfully provided her with monitored anesthesia care with propofol. Monitored anesthesia care with propofol may be effective for the general management of patients who have severe hyperventilation attacks and post-hyperventilation apnea. This case demonstrates that appropriate emergency treatment should be available for patients with hyperventilation attacks who are at risk of developing post-hyperventilation apnea associated with hypoxemia and loss of consciousness.
    Preview · Article · Dec 2014 · BioPsychoSocial Medicine
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    ABSTRACT: Hereditary angioedema (HAE) is a rare genetic disorder that causes a deficiency in or dysfunction of C1 esterase inhibitor (C1-INH) and is clinically characterized by sudden and recurrent attacks of angioedema. Although almost any part of the body can be affected, HAE is of greatest concern and can be life-threatening when the upper airway is involved, particularly the larynx (laryngeal attack). HAE attacks can be triggered by physical or psychological stress or can arise spontaneously without any apparent trigger. Dental treatments and routine oral surgical procedures, such as tooth extraction, abound with factors that can trigger an attack of HAE. Indeed, several cases of death resulting from HAE attacks have been reported after such procedures. Therefore, patients with HAE are of special concern in dentistry and require precautionary preparations before treatment. This report describes the successful management of tooth extractions in a patient with HAE who was at high risk of an HAE-induced laryngeal attack.
    No preview · Article · Aug 2014 · Journal of Oral and Maxillofacial Surgery
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    ABSTRACT: Continuous maintenance of an appropriate position of the mandible and head purely by manual manipulation is difficult, although the maneuver can restore airway patency during sleep and anesthesia. The aim of this paper was to examine the effect of head elevation with jaw closure using a remote-controlled airbag device, such as the airbag system, on passive upper airway collapsibility during propofol anesthesia. Seven male subjects were studied. Propofol infusion was used for anesthesia induction and maintenance, with a target blood propofol concentration of 1.5–2 (mu ) g/ml. Nasal mask pressure ( ({P}_{text {N}}) ) was intermittently reduced to evaluate upper airway collapsibility (passive ({P}_{_{text {CRIT}}}) ) and upstream resistance ( ({R}_{_{text {US}}}) ) at three different head and jaw positions, jaw opening position in the supine position, jaw opening position in the sniffing position with 6-cm head elevation, and jaw closure at a 6-cm height sniffing position. The 6-cm height sniffing position with jaw closure was achieved by an airbag device that was attached to the subject’s head-like headgear. Patient demographics, ({P}_{_{text {CRIT}}}) and ({R}_{_{text {US}}}) in each condition were compared using one-way ANOVA with a post hoc Tukey test. ({rm P}<0.05) was considered significant. We also confirmed the effects of our airbag device on improvement of upper airway collapsibility in three obstructive sleep apnea patients in a clinica- study. The combination of 6-cm head elevation with jaw closure using the air-inflatable robotic airbag system decreased upper airway collapsibility ( ({P}_{_{text {CRIT}}}sim -3.4) -cm H (_{2}) O) compared with the baseline position ( ({P}_{_{text {CRIT}}}sim -0.8) -cm H (_{2}) O, ({P} = 0.0001) ). In the clinical study, there was improvement of upper airway obstruction in sleep apnea patients, including decreased apnea and hypopnea duration and increased the lowest level of oxygen saturation. We demonstrated that establishment of head elevation with jaw closure achieved by a remote-controlled airbag device using an inflatable airbag system can produce substantial decreases in upper airway collapsibility and maintain upper airway patency during propofol anesthesia and sleep.
    Full-text · Article · Jan 2014 · IEEE Journal of Translational Engineering in Health and Medicine

  • No preview · Article · Jan 2014
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    ABSTRACT: The mechanism of agonist-induced GABA(B) receptor (GABA(B) R) internalization is not well understood. To investigate this process, we focused on the interaction of GABA(B) R with β-arrestins, which are key proteins in the internalization of most of the G protein-coupled receptors, and the agonist-induced GABA(B) R internalization and the interaction of GABA(B) R with β-arrestin1 and β-arrestin2 were investigated in real time using GABA(B) R and β-arrestins both of which were fluorescent protein-tagged. We then compared these profiles with those of μ-opioid receptors (μOR), well-studied receptors that associate and cointernalize with β-arrestins. When stimulated by the specific GABA(B) R agonist baclofen, GABA(B) R composed of GABA(B1a) R (GB(1a) R) and fluorescent protein-tagged GABA(B2) R-Venus (GB₂ R-V) formed functional GABA(B) R; they elicited G protein-activated inwardly rectifying potassium channels as well as nontagged GABA(B) R. In cells coexpressing GB(1a) R, GB₂ R-V, and β-arrestin1-Cerulean (βarr1-C) or β-arrestin2-Cerulean (βarr2-C), real-time imaging studies showed that baclofen treatment neither internalized GB₂ R-V nor mobilized βarr1-C or βarr2-C to the cell surface. This happened regardless of the presence of G protein-coupled receptor kinase 4 (GRK4), which forms a complex with GABA(B) R and causes GABA(B) R desensitization. On the other hand, in cells coexpressing μOR-Venus, GRK2, and βarr1-C or βarr2-C, the μOR molecule formed μOR/βarr1 or μOR/βarr2 complexes on the cell surface, which were then internalized into the cytoplasm in a time-dependent manner. Fluorescence resonance energy transfer assay also indicated scarce association of GB₂ R-V and β-arrestins-C with or without the stimulation of baclofen, while robust association of μOR-V with β-arrestins-C was detected after μOR activation. These findings suggest that GABA(B) Rs failure to undergo agonist-induced internalization results in part from its failure to interact with β-arrestins.
    No preview · Article · Sep 2012 · Synapse
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    ABSTRACT: To determine the mechanical upper airway properties and compensatory neuromuscular responses to obstruction during propofol anesthesia in the follicular and luteal phases of the menstrual cycle. Prospective, randomized study. University-affiliated hospital. 12 premenopausal female volunteers for studies of upper airway collapse throughout their menstrual cycle during the follicular phase (6 -10 days) and mid-late luteal phase (20 - 24 days). The level of propofol anesthesia (1.5 - 2.0 μg/mL) required to suppress arousal responses was determined by Observer's Assessment of Alertness/Sedation scoring (level 2) and confirmed by bispectral index monitoring. Pressure-flow relationships were constructed to evaluate collapsibility (P(CRIT)) and up-stream resistance (R(US)) during acute [Passive; hypotonic electromyography (EMG)] and sustained (Active; elevated EMG) changes in nasal mask pressure. The difference between passive P(CRIT) and active P(CRIT) (ΔP(CRIT A-P)) represented the magnitude of the compensatory response to obstruction. Passive P(CRIT) was significantly higher in the mid-late luteal phase (-4.7 cm H(2)O) than in the follicular phase (-6.2 cmH(2)O; P < 0.05). Active P(CRIT) significantly decreased compared with passive P(CRIT) in the follicular phase (-10.1 cm H(2)O) and in the mid-late luteal phase (-7.7 cm H(2)O) and (P < 0.05). No significant difference was noted in ΔP(CRIT) between the follicular (3.9 ± 2.9 cm H(2)O) and mid-late luteal phases (3.0 ± 2.6 cm H(2)O). No differences were seen in R(US) between the menstrual phases for either the passive (P = 0.8) or active (P = 0.75) states. Menstrual phase has an effect on anatomical alterations (mechanical properties) in the hypotonic upper airway during propofol anesthesia.
    Full-text · Article · Nov 2011 · Journal of clinical anesthesia
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    ABSTRACT: Head elevation can restore airway patency during anesthesia, although its effect may be offset by concomitant bite opening or accidental neck flexion. The aim of this study is to examine the effect of head elevation on the passive upper airway collapsibility during propofol anesthesia. Twenty male subjects were studied, randomized to one of two experimental groups: fixed-jaw or free-jaw. Propofol infusion was used for induction and to maintain blood at a constant target concentration between 1.5 and 2.0 μg/ml. Nasal mask pressure (PN) was intermittently reduced to evaluate the upper airway collapsibility (passive PCRIT) and upstream resistance (RUS) at each level of head elevation (0, 3, 6, and 9 cm). The authors measured the Frankfort plane (head flexion) and the mandible plane (jaw opening) angles at each level of head elevation. Analysis of variance was used to determine the effect of head elevation on PCRIT, head flexion, and jaw opening within each group. In both groups the Frankfort plane and mandible plane angles increased with head elevation (P < 0.05), although the mandible plane angle was smaller in the free-jaw group (i.e., increased jaw opening). In the fixed-jaw group, head elevation decreased upper airway collapsibility (PCRIT ~ -7 cm H₂O at greater than 6 cm elevation) compared with the baseline position (PCRIT ~ -3 cm H₂O at 0 cm elevation; P < 0.05). : Elevating the head position by 6 cm while ensuring mouth closure (centric occlusion) produces substantial decreases in upper airway collapsibility and maintains upper airway patency during anesthesia.
    Full-text · Article · Jun 2011 · Anesthesiology
  • S. KURATA · T. AYUSE · T. WATANABE · M. TACHI · N. IKEDA · K. OI
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    ABSTRACT: Objectives: It has been thought that the use of thinner needle is effective to overcome injection pain during dental local anesthesia. However there were few studies reported about the quantitative analysis of correlation between the diameter of dental needle and the pain by needle penetrations. Nanopasss™ (TERUMO, Tokyo, Japan) is a needle for subcutaneous insulin injection, its property has a 33 gauge needle (0.20 mm) with tapering structure to relieve injection pain. We examined about the level of pain produced by 31- (0.28mm), 33 (0.26mm) gauge dental needle and this tapered 33- gauge needle penetrations. Methods: Approval for this study was obtained from the ethics committee of Nagasaki University. 28 healthy volunteers (23 men, 5 women) aged 23 29 years participated. Each of the 28 subjects received needle penetrations to four areas of oral mucosa: inter-dental papilla (U1) and gingivobuccal fold (U2) of upper anterior teeth, inter-dental papilla (M1) and gingivobuccal fold (M2) of mandibular molar region with three kinds of needles. After each penetration, the subject assessed the level of discomfort using a 100-mm VAS with end points No pain and unbearable pain. Results: The mean of VAS scores was [U1; 55.4, U2; 53.3, M1; 45.8, M2; 37.8] in the penetrations of 31 G , [U1; 50.5, U2; 48.0, M1; 36.2, M2; 30.8] in 33 G, [U1; 55.1, U2; 48.5, M1; 36.9, M2; 28.6] in Nanopass™ (33G). There were no differences in reported VAS for needle penetrations to same area between 31-, 33- gauge dental needles and Nanopass™. Whereas the significant difference in VAS was reported between U1 and M2 to the penetration by the use of same gauge needle. Conclusion: This results indicates that tapering structure may contribute for pain perception during needle penetration.
    No preview · Conference Paper · Jul 2010
  • T Ayuse · S Ishitobi · H Yoshida · T Nogami · S Kurata · Y Hoshino · K Oi
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    ABSTRACT: The coordination between nasal breathing and non-nutritive swallowing serves as a protective reflex against potentially asphyxiating material, i.e. saliva and secretions, entering the respiratory tract. Although this protective reflex is influenced by positional changes in the head and body, the effect of mandible position on this reflex is not fully understood. We examined the effect of mandible advancement associated with mouth opening on the coordination between nasal breathing and non-nutritive swallowing induced by continuous infusion of distilled water into the pharyngeal cavity. The combination of mandible advancement and mouth opening increased the duration of swallowing apnoea and submental electromyographic burst duration. When the mandible was advanced with the mouth open, the duration of swallowing apnoea increased significantly compared with the centric position (0.79 +/- 0.23 vs. 0.64 +/- 0.12 s, P < 0.05, n = 12), and the duration of submental electromyographic activity increased significantly (2.11 +/- 0.63 vs. 1.46 +/- 0.25 s, P < 0.05, n = 12). Mandible advancement with mouth opening altered the respiratory phase resetting during swallowing and the timing of swallow in relation to respiratory cycle phase. We conclude that mandible re-positioning may strongly influence the coordination between nasal breathing and non-nutritive swallowing by altering respiratory parameters and by inhibiting movement of the tongue-jaw complex.
    No preview · Article · Mar 2010 · Journal of Oral Rehabilitation
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    ABSTRACT: Upper airway patency may be compromised during sleep and anesthesia by either anatomical alterations (mechanical properties) or disturbances in the neural control (compensatory neuromuscular responses). The pathophysiology of upper airway obstruction during anesthesia may differ between men and women. Recently, we reported that the upper airway mechanical properties were comparable with those found during natural nonrapid eye movement sleep, as evaluated by measurements of passive critical closing pressure (P(CRIT)) and upstream resistance (R(US)) during midazolam sedation. In this study, we compared the effects of gender on compensatory neuromuscular responses to upper airway obstruction during midazolam general anesthesia. Thirty-two subjects (14 men and 18 women) were studied. We constructed pressure-flow relationships to evaluate P(CRIT) and R(US) during midazolam anesthesia. The midazolam anesthesia was induced with an initial dose of midazolam (0.07-0.08 mg/kg bolus) and maintained by midazolam infusion (0.3-0.4 microg x kg(-1) x min(-1)), and the level of anesthesia was assessed by Ramsay score (Level 5) and Observer's Assessment of Alertness/Sedation score (Level 2). Polysomnographic and hemodynamic variables were monitored while nasal pressure (via mask), inspiratory air flow (via pneumotachograph), and genioglossal electromyograph (EMG(GG)) were recorded. P(CRIT) was obtained in both the passive condition, under conditions of decreased EMG(GG) (passive P(CRIT)), and in an active condition, whereas EMG(GG) was increased (active P(CRIT)). The difference between the active P(CRIT) and passive P(CRIT) (Delta P(CRIT) (P - A)) was calculated in each subject to determine the compensatory neuromuscular response. The difference between the active P(CRIT) and passive P(CRIT) (Delta P(CRIT) (A - P)) was significantly greater in women than in men (4.6 +/- 2.8 cm H(2)O and 2.2 +/- 1.7 cm H(2)O, respectively; P < 0.01), suggesting greater compensatory neuromuscular response to upper airway obstruction independent of arousal. We demonstrate that the arousal-independent compensatory neuromuscular responses to upper airway obstruction during midazolam anesthesia were partially maintained in women, and that gender may be a major determinant of the strength of compensatory responses during anesthesia.
    Full-text · Article · Oct 2009 · Anesthesia and analgesia
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    ABSTRACT: Upper airway obstruction during sleep can trigger compensatory neuromuscular responses and/or prolong inspiration in order to maintain adequate minute ventilation. The aim of this study was to investigate the strength of these compensatory responses during upper airway obstruction during propofol anesthesia. We assessed respiratory timing and upper airway responses to decreases in nasal pressure in nine propofol anesthetized normal subjects under condition of decreased (passive) and increased (active) neuromuscular activity. Critical closing pressure (PCRIT) and upstream resistance (RUS) were derived from pressure-flow relationships generated from each condition. The inspiratory duty cycle (IDC), maximum inspiratory flow (V1max) and respiratory rate (f) were determined at two levels of mean inspiratory airflow (VI; mild airflow limitation with VI > or = 150 ml s-1; severe airflow limitation with VI < 150 ml s-1). Compared to the passive condition, PCRIT decreased significantly (5.3 +/- 3.8 cm H2O, p < 0.05) and RUS increased (7.4 cm H2O ml-1 s, p < 0.05) in the active condition. The IDC increased progressively and comparably as decreased in both the passive and active conditions (p < 0.05). These findings imply that distinct compensatory mechanisms govern the modulation of respiratory pattern and pharyngeal patency during periods of airway obstruction under propofol anesthesia.
    Full-text · Article · Apr 2009 · Respiratory Physiology & Neurobiology

  • No preview · Article · Jan 2009 · Journal of Japanese Dental Society of Anesthesiology
  • T Ayuse · S Ishitobi · S Kurata · E Sakamoto · I Okayasu · K Oi
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    ABSTRACT: Chin-tuck position and reclining posture have been used in dysphagia patients to prevent aspiration during swallowing. However, both behavioural treatments may affect respiratory function. This study was carried out to test the hypothesis that if chin-tuck posture and body reclining affected respiratory function, this would be associated with altered coordination between respiration and swallowing. To investigate this hypothesis, respiratory parameters and manometry were used in each of four combinations of reclining posture and chin-tuck position. In the 60 degrees reclining with 60 degrees chin-tuck position, duration of swallowing apnea (0.89 s.d. 0.17 s) and submental electromyography burst (2.34 s.d. 0.84 s) were significantly longer when compared to both upright sitting and 30 degrees reclining positions. We conclude that 60 degrees reclining from vertical with 60 degrees chin-tuck may affect oral processing stages which delay and reduce a variety of oropharyngeal movements. These in turn significantly influence the coordination between respiration and swallowing.
    No preview · Article · Jul 2006 · Journal of Oral Rehabilitation
  • S. Kurata · T. Ayuse · K. Oi
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    ABSTRACT: It has been reported that hyperalgesia is caused by central sensitization in the spinal dorsal horn neuron due to activation of nociceptive transmission of nitric oxide (NO). Recently, it has been suggested that propofol, the most frequently used intravenous anesthetic agent for induction and maintenance of general anesthesia and sedation, may influence the production of NO in the central nervous system and systemic circulation. We hypothesized that subhypnotic doses of propofol may modulate hyperalgesia by altering the spinal release of nitric oxide. Although there are several studies that have reported the effect of propofol on pain perception and hyperalgesia, the results have been conflicting. In this study, we investigated the effects of intraperitoneal injection of propofol (40 mg/kg) on formalin-evoked spinal release of NO using microdialysis and the behavioral responses in conscious rats. Spinal dialysis catheters were implanted into the lumbar subarachnoid space of Wistar male rats under general anesthesia. On the test day after 4-5 days recovery from the surgical procedure, we performed subcutaneous formalin (5%, 50μl) injection to the plantar surface of the left hind paw in conscious rats. Formalin was injected 10 min after intraperitoneal injection of propofol (40 mg/kg) or saline. The measurement of spinal release of nitric oxide was analyzed every 10 min for 120 min using microdialysis. A flinching response was observed at 1 and 5 min after formalin injection, and every 5 min thereafter for 60 min. The number of flinches was counted for each l min period. In this preliminary study, NO production did not change significantly in the propofol 40 mg/kg i.p. group compared with the basal level. In the saline group, NO production increased significantly 132.3±8.8%, 133.1± 7.9%, 132.5±8.1%, 132.2±7.2% at 40, 50, 60 and 70 min after formalin injection compared with basal levels (mean±SEM, n=8, p<0.05). In the propofol group, NO production did not increase significantly compared with the basal level. There was a significant difference in NO production between the propofol group and the saline group after formalin injection (mean±SEM, n=8 per group, p<0.05). Corresponding to phase 2 behaviour, there was a significant decrease in the total number of flinches from 5 min to 60 min after formalin injection in the propofol group, compared to the saline group (n=8 per group, p< 0.05). In conclusion, intraperitoneal injection of propofol (40 mg/kg) suppressed NO production in the spinal cord and decreased the total number of flinches in phase 2 in the formalin test in rats.
    No preview · Article · Jan 2006 · Journal of Japanese Dental Society of Anesthesiology