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Biomedical subjects

M Yamakage

Publications and source records attributed to M Yamakage.

At least 19 recordsLinked to original sources
PubMed2006

Performance of three systems for warming intravenous fluids at different flow rates.

This study compared the intravenous fluid warming capabilities of three systems at different flow rates. The devices studied were a water-bath warmer, a dry-heat plate warmer, and an intravenous fluid tube warmer Ambient temperature was controlled at 22 degrees to 24 degrees C. Normal saline (0.9% NaCl) at either room temperature (21 degrees to 23 degrees C) or at ice-cold temperature (3 degrees to 5 degrees C) was administered through each device at a range of flow rates (2 to 100 ml/min). To mimic clinical conditions, the temperature of the fluid was measured with thermocouples at the end of a one metre tube connected to the outflow of the warmer for the first two devices and at the end of the 1.2 m warming tubing for the intravenous fluid tube warmer The temperature of fluid delivered by the water bath warmer increased as the flow rate was increased up to 15 to 20 ml/min but decreased with greater flow rates. The temperature of the fluid delivered by the dry-heat plate warmer significantly increased as the flow rate was increased within the range tested (due to decreased cooling after leaving the device at higher flow rates). The temperature of fluid delivered by the intravenous fluid tube warmer did not depend on the flow rate up to 20 ml/min but significantly and fluid temperature-dependently decreased at higher flow rates (>30 ml/min). Under the conditions of our testing, the dry heat plate warmer delivered the highest temperature fluid at high flow rates.

Anesthetics, Intravenous↗
PubMed2005

Intermittent pneumatic foot compression can activate blood fibrinolysis without changes in blood coagulability and platelet activation.

BACKGROUND: Intermittent pneumatic foot compression (IPC) is a useful technique for prophylaxis of peri-operative venous thromboembolism. The aim of this study was to determine the effect of IPC on blood coagulation/fibrinolysis and platelet function using a blood viscometer (Sonoclot) and a platelet aggregation monitor (WBA analyzer(TM)), respectively. Using the same blood samples, serum levels of tissue-type plasminogen activator (t-PA), thrombomodulin (TM) and activated protein C (APC) were also measured. METHODS: The soles and legs of each subject (n = 8) were compressed for 3 s (130 mmHg) at a 0.3-Hz interval using an IPC device. Parameters were measured 2 min before and at the end of 60-min compression. RESULTS: Parameters of the Sonoclot time-to-peak were shortened and clot retraction rate was increased significantly by IPC, whereas the other parameters did not change. These results indicate that IPC can activate blood fibrinolysis but not coagulability. A parameter of the WBA analyzer PATI (platelet aggregatory threshold index) did not change, indicating that IPC cannot activate platelet function per se. The concentration of t-PA decreased slightly but significantly. A decrease in the concentration of t-PA can lead to activation of fibrinolysis. Other humoral parameters did not change, indicating that IPC has no effect on endothelial function. Although neither blood coagulability nor platelet function were affected by IPC, fibrinolytic activity increased slightly, probably by activation of t-PA function. CONCLUSION: IPC is useful for prophylaxis for thromboembolism by activation of blood fibrinolysis as well as inhibition of blood stasis.

Activated Protein C Resistance↗
PubMed2005

Comparative study between propofol in a long-chain triglyceride and propofol in a medium/long-chain triglyceride during sedation with target-controlled infusion.

This study was performed to compare the pharmacological characteristics of propofol in an emulsion of both medium- and long-chain triglycerides (MCT/LCT) with those of propofol in an LCT emulsion, by measuring the sedative level and the plasma concentration of propofol during sedation using a target-controlled infusion (TCI) technique. Forty ASA 1 or 2 adult patients who required spinal anaesthesia for surgery were enrolled in this study. The patients were divided into two groups: a propofol LCT group (n = 20) and a propofol MCT/LCT group (n = 20). Propofol was injected intravenously at target blood concentrations of 2.0, 3.0 and 4.0 microg x ml(-1). The bispectral (BIS) index was recorded, and arterial blood was drawn to measure the actual plasma concentrations of propofol at each predicted concentration. Propofol was assayed by high-performance liquid chromatography. Propofol MCT/LCT was associated with significantly less pain than propofol LCT (P < 0.05). There were no significant differences between the two groups in BIS index or in plasma concentration of propofol at each predicted concentration. Computer-generated TCI of propofol MCT/LCT during sedation is comparable with that of propofol LCT with respect to pharmacokinetics and pharmacodynamics. The formulation of MCT/LCT has a beneficial effect with respect to less pain on injection.

Adult↗
PubMed2004

The type of carbon dioxide absorbent has no relation to the concentration of carbon monoxide in the breathing circuit during low-flow isoflurane anaesthesia in smoking and non-smoking subjects.

The present study was designed to investigate the concentrations of carbon monoxide (CO) in the anaesthetic circuit and of arterial carboxyhaemoglobin (COHb) during low-flow isoflurane anaesthesia in smoking and non-smoking subjects using three kinds of cardon dioxide (CO2) absorbent. Thirty smoking and 30 non-smoking subjects were selected for this study, and these two groups were each divided into three groups according to the type of CO2 absorbent used (Wakolime A, Drägersorb Free, and Amsorb). Anaesthesia was maintained with 1.0% isoflurane and nitrous oxide (1. 0 l min(-1))/oxygen (1.0 l min(-1)). Concentrations of CO in the inspired breathing circuit and concentrations of arterial COHb were measured at 0, 1, 2, 3, and 4 hours after exposure to isoflurane. In the smoking groups there were no significant differences in CO concentrations in the circuit between the groups and the CO concentrations did not change significantly during the study period. There were also no significant differences in the arterial COHb values between the groups and the COHb concentrations remained constant. There was a significant linear correlation between the concentrations of CO and COHb (r=0.86, n =30, P<0.001). In the non-smoking groups all of the parameters remained constant at low levels that were independent of the type of CO2 absorbents tested. The major source for increased intraoperative CO exposure is related to the patient's smoking status, and the type of CO2 absorbent used has no relation to an increase in CO concentration in the breathing circuit.

Absorption↗
PubMed2004

Reductions in levels of bacterial superantigens/cannabinoids by plasma exchange in a patient with severe toxic shock syndrome.

Toxic shock syndrome is a rare but potentially fatal toxin-mediated febrile illness. We report a case of toxic shock syndrome complicated by life-threatening organ dysfunction with high toxin-1 and staphylococcus enterotoxin type A levels that were successfully reduced by early introduction of plasma exchanges. The report shows the time course of the concentrations of anandamide and 2-arachidonyl glyceride and confirms that early introduction of plasma exchange can result in a rapid reduction of circulating toxins and mediators in the treatment of life-threatening multiple organ dysfunction.

Adolescent↗
PubMed2001

Use of the fibreoptic stylet scope (Styletscope) reduces the hemodynamic response to intubation in normotensive and hypertensive patients.

PURPOSE: To compare hemodynamic changes after tracheal intubation when using a new fibreoptic stylet scope (Styletscope) and a conventional laryngoscope in normotensive and hypertensive patients. METHODS: Normotensive (N; n=30) and hypertensive (H; n=30) patients undergoing general anesthesia participated in this study. Each group was divided into two groups. In one group, patients were intubated by using a stylet scope with a laryngoscope as an adjuvant (S; n=15 each), while patients in the other group were intubated using a laryngoscope by the usual technique (L; n=15 each). The time necessary for intubation, hemodynamic changes, and adverse effects were recorded. RESULTS: Patients in the normotensive groups (SN and LN groups) showed significant increases in both systolic and diastolic blood pressures from before induction to one minute after intubation; however, blood pressures in the SN group were significantly lower than those in the LN group. Both systolic and diastolic blood pressures increased after intubation in the LH group, but not in the SH group. Heart rates in all four groups showed significant increases, and there were no differences between heart rates in the stylet scope and laryngoscope groups or between the normotensive and hypertensive groups. The number of patients who complained of sore throat was greater in the laryngoscope groups. CONCLUSIONS: Tracheal intubation with a stylet scope can attenuate hemodynamic changes and reduce the incidence of sore throat in comparison with the conventional laryngoscope technique in both normotensive and hypertensive patients.

Anesthesia, General↗
PubMed2001

Production of compound A under low-flow anesthesia is affected by type of anesthetic machine.

PURPOSE: The purpose was to compare the concentrations of compound A in inspired gas breathed by patients produced by different types of anesthetic machines under prolonged sevoflurane low-flow anesthesia. METHODS: The anesthetic machines tested were Excel 210 SE (Datex-Ohmeda, Louisville, CO), Cicero (Dräger, Lübeck, Germany), and AS/3 ADU (Datex-Ohmeda, Louisville, CO). Anesthesia expected to last more than four hours was maintained with 2.0% sevoflurane and nitrous oxide (0.5 L x min(-1))/oxygen (0.5 L x min(-1)). The concentrations of compound A, obtained from the inspiratory limb of the circle system, were measured using a gas chromatograph. RESULTS: When Excel and Cicero were used, concentrations of compound A increased steadily from the baseline values to 28 and 29 (mean) ppm, respectively, at two hours after exposure to sevoflurane and became constant. There was no significant difference between the concentrations of compound A produced by these anesthetic machines. In contrast, the new anesthetic machine AS/3 was associated with lower concentrations of compound A (6 ppm at one hour, P <0.05 compared with Excel and Cicero), and the concentration did not change significantly thereafter. CONCLUSION: In spite of the use of a conventional carbon dioxide (CO2) absorbent with strong bases, the anesthetic machine AS/3 with a small volume of canister/soda lime (900 ml/700 ml) produced lower concentrations of compound A than those produced by the other machines.

Anesthesia, Inhalation↗
PubMed2001

Celite-activated viscometer Sonoclot can measure the suppressive effect of tranexamic acid on hyperfibrinolysis in cardiac surgery.

PURPOSE: To investigate the usefulness of the celite-activated viscometer Sonoclot for monitoring fibrinolytic status in cardiac surgery, we demonstrated the effectiveness of high doses of tranexamic acid, an antifibrinolytic agent, in reducing postoperative bleeding. METHODS: Thirty-two American Society of Anesthesiologists (ASA) physical status III patients who required cardiac surgery with cardiopulmonary bypass (CPB) were studied. Anesthesia was induced by a high dose of fentanyl and midazolam with oxygen and was maintained by the intermittent administration of these agents. Patients were divided into two groups: the control group (n = 15) and patients receiving tranexamic acid (TA; n = 17). The TA group received a high dose (50 mg/kg) of TA twice, once before and once after CPB. The percentage diminishing rate of the Sonoclot tracing 15 min after maximum clot signal (DR(15)) and the amount of postoperative bleeding were measured. RESULTS: After CPB, DR(15) in the control group (mean 28.3%) increased significantly by 45%, and the DR(15) in the TA group (16.1%) was significantly lower than that in the control group. The amount of postoperative bleeding in the TA group (546 ml) was significantly less, by 34%, than that in the control group (829 ml). CONCLUSION: Prophylactic administration of high-dose TA in cardiac surgery reduces postoperative bleeding, and this effect is consistent with changes in the diminishing rate using Sonoclot. The celite-activated viscometer Sonoclot is recommended for use in cardiac surgery for rapid assessment of fibrinolytic status.

Journal Article↗
PubMed2001

Different inhibitory effects of volatile anesthetics on T- and L-type voltage-dependent Ca2+ channels in porcine tracheal and bronchial smooth muscles.

BACKGROUND: The distal airway is more important in the regulation of airflow resistance than is the proximal airway, and volatile anesthetics have a greater inhibitory effect on distal airway muscle tone. The authors investigated the different reactivities of airway smooth muscles to volatile anesthetics by measuring porcine tracheal or bronchial (third to fifth generation) smooth muscle tension and intracellular concentration of free Ca2+ ([Ca2+]i) and by measuring inward Ca2+ currents (ICa) through voltage-dependent Ca2+ channels (VDCs). METHODS: Intracellular concentration of free Ca2+ was monitored by the 500-nm light emission ratio of Ca2+ indicator fura-2. Isometric tension was measured simultaneously. Whole-cell patch clamp recording techniques were used to investigate the effects of volatile anesthetics on ICa in dispersed smooth muscle cells. Isoflurane (0-1.5 minimum alveolar concentration) or sevoflurane (0-1.5 minimum alveolar concentration) was introduced into a bath solution. RESULTS: The volatile anesthetics tested had greater inhibitory effects on carbachol-induced bronchial smooth muscle contraction than on tracheal smooth muscle contraction. These inhibitory effects by the anesthetics on muscle tension were parallel to the inhibitory effects on [Ca2+]i. Although tracheal smooth muscle cells had only L-type VDCs, some bronchial smooth muscle cells (approximately 30%) included T-type VDC. Each of the two anesthetics significantly inhibited the activities of both types of VDCs in a dose-dependent manner; however, the anesthetics had greater inhibitory effects on T-type VDC activity in bronchial smooth muscle. CONCLUSIONS: The existence of the T-type VDC in bronchial smooth muscle and the high sensitivity of this channel to volatile anesthetics seem to be, at least in part, responsible for the different reactivities to the anesthetics in tracheal and bronchial smooth muscles.

Anesthetics, Inhalation↗
PubMed2001

Mechanisms of direct inhibitory action of propofol on uterine smooth muscle contraction in pregnant rats.

BACKGROUND: Although propofol directly inhibits uterine smooth muscle contraction, the mechanisms of this effect are still unknown. The current study aimed to clarify the mechanisms of the inhibitory effect of propofol on oxytocin-induced uterine smooth muscle contraction by measuring (1) the concentration of intracellular free Ca(2+) ([Ca(2+)](i)) simultaneously with muscle tension, (2) the amount of intracellular inositol 1,4,5-triphosphate ([IP(3)](i)), and (3) voltage-dependent Ca(2+) channel (VDCC) activity. METHODS: Uterine smooth muscle tissues were obtained from pregnant rats (in late gestation). [Ca(2+)](i) with isometric tension was monitored by the 500-nm light emission ratio of preloaded Ca(2+) indicator fura-2. [IP(3)](i) and VDCC activity were measured by radioimmunoassay and patch clamp techniques, respectively. The uterine smooth muscle was stimulated by 20 nm oxytocin and exposed to propofol (10(-7) approximately 10(-4) m). RESULTS: Propofol had significant inhibitory effects on oxytocin-induced uterine smooth muscle contraction and increased [Ca(2+)](i) in pregnant rats in a dose-dependent manner, without affecting the agonist-receptor binding affinity. Propofol inhibited the increase in [IP(3)](i) induced by oxytocin. Propofol also inhibited VDCC activity in both activated and inactivated states. The solvent Intralipid had no effects on these parameters. CONCLUSIONS: Propofol inhibits oxytocin-induced uterine smooth muscle contraction, at least in part, by decreasing [Ca(2+)](i) without affecting agonist-receptor binding; the inhibitory effect of propofol on [Ca(2+)](i) might be mediated both by a decrease in [IP(3)](i) and by inhibition of VDCC activity.

Anesthetics, Intravenous↗
PubMed2001

Anesthetic effects on mitochondrial ATP-sensitive K channel.

BACKGROUND: Volatile anesthetics show an ischemic preconditioning-like cardioprotective effect, whereas intravenous anesthetics have cardioprotective effects for ischemic-reperfusion injury. Although recent evidence suggests that mitochondrial adenosine triphosphate-regulated potassium (mitoK(ATP)) channels are important in cardiac preconditioning, the effect of anesthetics on mitoK(ATP) is unexplored. Therefore, the authors tested the hypothesis that anesthetics act on the mitoK(ATP) channel and mitochondrial flavoprotein oxidation. METHODS: Myocardial cells were isolated from adult guinea pigs. Endogenous mitochondrial flavoprotein fluorescence, an indicator of mitochondrial flavoprotein oxidation, was monitored with fluorescence microscopy while myocytes were exposed individually for 15 min to isoflurane, sevoflurane, propofol, and pentobarbital. The authors further investigated the effect of 5-hydroxydeanoate, a specific mitoK(ATP) channel antagonist, on isoflurane- and sevoflurane-induced flavoprotein oxidation. Additionally, the effects of propofol and pentobarbital on isoflurane-induced flavoprotein oxidation were measured. RESULTS: Isoflurane and sevoflurane induced dose-dependent increases in flavoprotein oxidation (isoflurane: R2 = 0.71, n = 50; sevoflurane: R2 = 0.86, n = 20). The fluorescence increase produced by both isoflurane and sevoflurane was eliminated by 5-hydroxydeanoate. Although propofol and pentobarbital showed no significant effects on flavoprotein oxidation, they both dose-dependently inhibited isoflurane-induced flavoprotein oxidation. CONCLUSIONS: Inhalational anesthetics induce flavoprotein oxidation through opening of the mitoK(ATP) channel. This may be an important mechanism contributing to anesthetic-induced preconditioning. Cardioprotective effects of intravenous anesthetics may not be dependent on flavoprotein oxidation, but the administration of propofol or pentobarbital may potentially inhibit the cardioprotective effect of inhalational anesthetics.

ATP-Binding Cassette Transporters↗
PubMed2001

[Comparative survey of cardiac arrests during anesthesia and surgery in the 1980 s and 1999 s].

A survey of unexpected cardiac arrests, excluding those associated with cardiac surgery, that had occurred during anesthesia and surgery in the period 1980-1999 was conducted. There was no significant difference between the number of such cardiac arrests that occurred in the 1980 s (29/36,159, 0.080%) and the number in the 1990 s (33/37,643, 0.088%). According to the classification by Keenan et al., there were 3 cases (0.0083%) in the 80 s and 4 cases (0.0106%) in the 90 s that occurred due to anesthetic management. Cardiac arrests due to surgery itself significantly decreased from 21 cases in the 80 s to 6 cases in the 90 s, probably due to proper treatment for massive bleeding, a decrease in the number of cases of anaphylactic shock, and the development of novel anesthetics. Conversely, cardiac arrests due to preoperative conditions of the patients significantly increased from 5 cases in the 80 s to 23 cases in the 90 s. This increase seems to be due to an increase in the number of severe and multiple injuries and an increase in complicated major surgery. The increase in number of cases due to preoperative conditions also depends on coronary spasm and cardiac conduction insufficiency. Taking into consideration the improvement in intraoperative monitoring and the development of novel anesthetics in the 90 s, greater efforts should be made by anesthesiologists to reduce the incidence of cardiac arrest due to anesthetic management, and preoperative evaluation of surgical patients needs to be reconsidered.

Anesthesia↗
PubMed2001

[Changes in sedative level during induction of anesthesia using a single volatile anesthetic].

We investigated the changes in sedative level during induction of anesthesia using a single volatile anesthetic, sevoflurane, compared with the changes when propofol and sevoflurane were used. We used a bispectral index (BIS) monitor (Aspect, Newton, USA) to monitor the sedative level. Thirty patients were randomly divided into one group receiving sevoflurane alone (S group, n = 15) and another group receiving propofol and sevoflurane (PS group, n = 15). The S group received 5% sevoflurane with nitrous oxide 6 l.min-1 and oxygen 3 l.min-1 via a face mask, while the PS group received propofol 1.5 mg.kg-1 i.v. followed by step-wise increasing sevoflurane up to 5%. Induction times, as assessed by loss of eyelash reflex, were 32 s in the PS group and 65 s in the S group. The decrease in the BIS value was smooth in the S group, whereas it increased transiently and varied greatly in the PS group. Two patients in the PS group showed body movement during induction of anesthesia, and the BIS values in both cases transiently exceeded 60. BIS monitor is useful for monitoring the sedative level during induction of anesthesia, and induction using a single volatile anesthetic such as sevoflurane is smooth.

Adult↗
PubMed2000

Predictive variables of hypothermia in the early phase of general anesthesia.

UNLABELLED: Core temperature decreases precipitously for 1 h and then decreases slowly for 2-3 h after the induction of general anesthesia. We investigated the predictive variables of hypothermia by measuring peripheral skin temperature and total body fat (TBF). We studied 60 adult patients who required general anesthesia with isoflurane. The following variables were measured preoperatively: right palmar skin temperature by using an infrared thermometer and skin thickness at arm and scapula by using a standard caliper. TBF was calculated by using the regression equation of Durnin and Womersley. Rectal temperature, taken to represent core temperature, was measured during the operation. The gradient of hypothermia induced by general anesthesia was divided into two parts: 1) a precipitous decrease for the first hour and 2) a slow decrease for the following 2-3 h. Preoperative palmar skin temperature had a significant linear relationship with the precipitous decrease in temperature over the first hour (r = 0.69, P < 0.0001), and TBF had a significant linear relationship with the subsequent slow decrease in temperature (r = 0. 63, P < 0.0001). By simple measurements, we can predict the extent of hypothermia in the early phase of general anesthesia and prevent its onset by using body-warming techniques. IMPLICATIONS: After the induction of general anesthesia, palmar skin temperature had a linear relationship with the precipitous decrease in rectal temperature over the first hour, and total body fat had a linear relationship with the subsequent decrease in temperature. Thus, by simple measurements, we can predict the extent of hypothermia in the early phase of general anesthesia.

Aged↗
PubMed2000

Carbon dioxide absorbents containing potassium hydroxide produce much larger concentrations of compound A from sevoflurane in clinical practice.

UNLABELLED: We investigated the concentrations of degraded sevoflurane Compound A during low-flow anesthesia with four carbon dioxide (CO(2)) absorbents. The concentrations of Compound A, obtained from the inspiratory limb of the circle system, were measured by using a gas chromatograph. In the groups administered 2 L/min fresh gas flow with 1% sevoflurane, when the conventional CO(2) absorbents, Wakolime(TM) (Wako, Tokyo, Japan) and Drägersorb(TM) (Dräger, Lübeck, Germany), were used, the concentrations of Compound A increased steadily from a baseline to 14.3 ppm (mean) and 13.2 ppm, respectively, at 2 h after exposure to sevoflurane. In contrast, when the other novel types of absorbents containing decreased or no potassium hydroxide/sodium hydroxide, Medisorb(TM) (Datex-Ohmeda, Louisville, CO) and Amsorb(TM) (Armstrong, Coleraine, Northern Ireland), were used, Compound A remained at baseline (<2 ppm) throughout the study. In the groups administered 1 L/min fresh gas flow with 2% sevoflurane, Wakolime(TM) and Drägersorb(TM) produced much larger concentrations of Compound A (35.4 ppm and 34.2 ppm, respectively) at 2 h after exposure to sevoflurane. Medisorb(TM) showed measurable concentrations of Compound A (8.6 ppm at 2 h), but they were significantly smaller than those produced by the two conventional absorbents. In contrast, when Amsorb(TM) was used, Compound A concentrations remained at baseline throughout the study period. IMPLICATIONS: Carbon dioxide absorbents containing potassium hydroxide/sodium hydroxide produce much larger concentrations of Compound A from sevoflurane in clinical practice. An absorbent containing neither potassium hydroxide nor sodium hydroxide produces the smallest concentrations of Compound A.

Absorption↗
PubMed2000

Interaction between volatile anesthetics and hypoxia in porcine tracheal smooth muscle.

UNLABELLED: We investigated the direct interaction between the volatile anesthetics, isoflurane and sevoflurane, and hypoxia in porcine tracheal smooth muscle in vitro by simultaneously measuring muscle tension and intracellular concentration of free Ca(2+) ([Ca2+]i). Muscle tension was measured by using an isometric transducer, and [Ca2+]i was measured by using fura-2, an indicator of Ca2+. Under the condition of bubbling with 95% O2/5% CO2, [Ca2+]i was increased by 1 microM carbachol with a concomitant contraction. Volatile anesthetics significantly inhibited both carbachol-induced muscle contraction and increase in [Ca2+]i. Hypoxia bubbled with 95% N(2)/5% CO2 inhibited the muscle contraction by 30% with an increase in [Ca2+]i by 20%. Exposure to hypoxia substantially enhanced the inhibitory effects of these anesthetics on carbachol-induced muscle contraction, whereas the decreases in [Ca2+]i were significantly prevented by hypoxia. Under Ca2+-free conditions, hypoxia significantly decreased the muscle contraction by 20%; however, it still increased [Ca2+]i by 15%. Exposure to the anesthetics significantly enhanced the inhibitory effect of hypoxia on the muscle contraction; however, it appeared to have little effect on [Ca2+]i. Hypoxia inhibits airway smooth muscle contraction independently of intracellular Ca2+, and it substantially potentiates the inhibitory effects of volatile anesthetics on airway smooth muscle contraction. IMPLICATIONS: Hypoxia inhibits agonist-induced tracheal smooth muscle contraction with an increase in free Ca2+ [Ca2+]i, which comes from intracellular Ca2+ stores. Hypoxia also potentiates the inhibitory effect of volatile anesthetics on airway smooth muscle contraction. Conversely, there is a possibility that the treatment of asthmatic patients with oxygen partially attenuates the inhibitory effect of volatile anesthetics on airway smooth muscle contractility.

Analysis of Variance↗