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Ken Yamaura Last modified date:2020.08.02

Undergraduate School

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Department of Anesthesiology and Critical Care Medicine, Graduate School of Medical Sciences, Kyushu University .
Academic Degree
Medical Doctor
Country of degree conferring institution (Overseas)
Field of Specialization
Total Priod of education and research career in the foreign country
Outline Activities
Cardiovascular Anesthesia
Research Interests
  • Anesthetic management in patients with left ventricular dysfunction
    keyword : LV diastolic function, anesthesia
  • Neuropathic pain
    keyword : neuropathic pain
  • postoperative cognitive dysfunction
    keyword : surgery anesthesia cognitive dysfunction
  • Circulation and coagulation control during operative period
    keyword : Circulation coagulation Anesthesia
  • Evaluation of the perioperative cardiac function using transesophageal echocardiaography
    keyword : Transesophageal echocardiography cardiac function perioperqative
    1996.04~2010.03Evaluation of cardiac function using transesophageal echocardiography.
Academic Activities
1. Midoriko Higashi, Kenji Shigematsu, Kenji Tominaga, Kazuya Murayama, Daisuke Seo, Toshikazu Tsuda, Gen Maruta, Kohei Iwashita, Ken Yamaura, Preoperative elevated E/e’ (≥ 15) with preserved ejection fraction is associated with the development of postoperative heart failure in intermediate-risk non-cardiac surgical patients, Journal of Anesthesia, 10.1007/s00540-019-02728-z, 34, 2, 250-256, 2020.04, Purpose: Left ventricular diastolic dysfunction is an independent risk factor for adverse cardiovascular morbidities and mortalities in cardiovascular and high-risk surgical patients. However, there were only a few investigations among intermediate-risk surgical patients. This study aimed to investigate postoperative heart failure (HF) in intermediate-risk surgical patients who had preoperative diastolic dysfunction with preserved ejection fraction (EF). Methods: Consecutive patients underwent intermediate-risk surgery between January 2016 and December 2018 were retrospectively evaluated. Patients with preserved EF were divided into three groups using one of the parameters of diastolic function: the ratio of early diastolic filling velocity to the peak diastolic velocity of mitral medial annulus (E/e’) ≥ 15, E/e’ between 8 and 15, and E/e’ < 8. Postoperative HF was defined as clinical symptoms and radiological evidence and low SpO2 less than 93%. The primary outcome was the incidence of postoperative HF and its relation to preoperative E/e’. Chi-squared test, unpaired t test with Welch’s correction, and multivariate logistic regression were used for analysis. Results: In total, 965 patients were included in the final analysis. Postoperative HF developed in 36/965 (3.7%) patients with preserved EF. The incidence of postoperative HF was stratified according to the E/e’, and the rates of HF occurrence in patients with E/e’ < 8, 8–15, and ≥ 15 were 1.8%, 2.7%, and 15%, respectively (P < 0.01). Conclusion: Preoperative elevated E/e’ (≥ 15) was associated with the development of postoperative HF in intermediate-risk surgical patients with preserved EF..
2. M. Higashi, K. Yamaura, Mizuko Ikeda, Tsukasa Shimauchi, H. Saiki, Sumio Hoka, Diastolic dysfunction of the left ventricle is associated with pulmonary edema after renal transplantation, Acta Anaesthesiologica Scandinavica, 10.1111/aas.12168, 57, 9, 1154-1160, 2013.10, Background Post-operative pulmonary complications are associated with high mortality and graft loss in renal transplantation recipients. Left ventricular diastolic dysfunction is not uncommon in patients with chronic renal failure, including those with preserved left ventricular systolic function. The purpose of this study was to determine the relationship between left ventricular diastolic dysfunction and incidence of post-operative pulmonary edema in renal transplantation recipients with preserved left ventricular systolic function. Methods Pre-operative left ventricular function and incidence of pulmonary edema were retrospectively studied in 209 patients who underwent living-donor renal transplantation between January 2010 and October 2012. Left ventricular systolic and diastolic functions were evaluated by ejection fraction and E/E' ratio, retrospectively, using transthoracic echocardiography. Pulmonary edema was defined by evidence of pulmonary congestion on the chest X-ray together with PaO2/FiO2 ratio < 300 mmHg. Results Eleven out of 190 (5.8%) renal transplantation patients with preserved left ventricular systolic function developed post-operative pulmonary edema. Patients with pulmonary edema had a significantly higher geometric mean (95% confidence interval) of E/E' ratio than those without pulmonary edema [17.8 (14.1-22.5) vs. 11.1 (10.6-11.7), P = 0.001]. Conclusion Pre-operative left ventricular diastolic dysfunction correlated with the development of post-operative pulmonary edema in renal transplantation recipients. Meticulous intraoperative volume therapy is important to avoid post-operative pulmonary edema in such patients..
3. Ken Yamaura, D. Gebremedhin, C. Zhang, J. Narayanan, K. Hoefert, E. R. Jacobs, R. C. Koehler, D. R. Harder, Contribution of epoxyeicosatrienoic acids to the hypoxia-induced activation of Ca2+-activated K+ channel current in cultured rat hippocampal astrocytes, Neuroscience, 10.1016/j.neuroscience.2006.08.021, 143, 3, 703-716, 2006.12, Brief hypoxia differentially regulates the activities of Ca2+-activated K+ channels (KCa) in a variety of cell types. We investigated the effects of hypoxia (<2% O2) on KCa channel currents and on the activities of cytochrome P450 2C11 epoxygenase (CYP epoxygenase) in cultured rat hippocampal astrocytes. Exposure of astrocytes to hypoxia enhanced macroscopic outward KCa current, increased the open state probability (NPo) of 71 pS and 161 pS single-channel KCa currents in cell-attached patches, but failed to increase the NPo of both the 71 pS and 161 pS KCa channel currents recorded from excised inside-out patches. The hypoxia-induced enhancement of macroscopic KCa current was attenuated by pretreatment with tetraethylammonium (TEA, 1 mM) or during recording using low-Ca2+ external bath solution. Exposure of astrocytes to hypoxia was associated with generation of superoxide as detected by staining of cells with the intracellular superoxide detection probe hydroethidine (HE), attenuation of the hypoxia-induced activation of unitary KCa channel currents by superoxide dismutation with tempol, and as quantitated by high-pressure liquid chromatography/fluorescence assay using HE as a probe. In cultured astrocytes in which endogenous CYP epoxygenase activity has been inhibited with either miconazole or N-methylsulfonyl-6-(2-propargyloxyphenyl) hexanamide (MSPPOH) hypoxia failed to increase the NPo of both the 71 pS and 161 pS KCa currents and generation of superoxide. Hypoxia increased the level of P450 epoxygenase protein and production of epoxyeicosatrienoic acids (EETs) from cultured astrocytes, as determined by immunohistochemical staining and LC/MS analysis, respectively. Exogenous 11,12-EET increased the NPo of both the 71 pS and 161 pS KCa single-channel currents only in cell-attached but not in excised inside-out patches of cultured astrocytes. These findings indicate that hypoxia enhances the activities of two types of unitary KCa currents in astrocytes by a mechanism that appears to involve CYP epoxygenase-dependent generation of superoxide and increased production or release of EETs..
4. Ken Yamaura, Sumio Hoka, Hirotsugu Okamoto, Shosuke Takahashi, Quantitative Analysis of Left Ventricular Regional Wall Motion with Color Kinesis during Abdominal Aortic Cross-Clamping, Journal of Cardiothoracic and Vascular Anesthesia, 10.1053/j.jvca.2003.09.005, 17, 6, 703-708, 2003.12, Objectives: The authors aimed to establish a technique for quantitative analysis of regional wall motion abnormality (RWMA) using color kinesis (CK) of transesophageal echocardiography (TEE) in surgical patients. This technique was used to determine whether RWMAs develop de novo after infrarenal aortic cross-clamping in patients undergoing vascular surgery with a preoperative dipyridamole thallium stress test (DTST). Design: An observational study. Setting: University hospital. Participants: Thirty-eight patients undergoing infrarenal abdominal aortic aneurysm resection or aortofemoral bypass. Measurements and Main Results: CK images of the left ventricle (LV) were obtained from the midventricular transgastric short-axis view before and after infrarenal aortic cross-clamping using TEE and analyzed off-line using custom software. The predictive value of the category "reversible perfusion defect" (RD) was also estimated from DTST for predicting new RWMAs with CK. CK analysis is suitable for clinical use based on the comparison with conventional two-dimensional echocardiogram measurements and inter-observer variability. CK analysis showed all 7 patients with persistent perfusion defects on DTST had RWMAs. New RWMAs occurred in 2 of 9 patients with RD and in 2 of 15 patients with normal DTST, indicating that there was no significant difference between RD and normal DTST in the incidence of new RWMAs. Conclusions: A new method is available for clinical use, which is capable of visualizing RWMAs. These results suggest that new RWMAs introduced by aortic cross-clamping occur irrespective of the risk as assessed by preoperative DTST. CK with the new analysis method might be a useful tool to quantitatively evaluate RWMAs during surgery..
Membership in Academic Society
  • Japanese Association for operative Medicine
  • American Society of Anesthesiologists
  • Japanese Society of Anesthesiologists
  • The Japan Society for Clinical Anesthesia
  • Japan Society of Circulation Control in Medicine
  • Japanese Society of Cardiovascular anesthesiologists
Educational Activities
Clinical Cardiovascular Anesthesia