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Abstract PR618: Response of Arterial Mechanical Impedance to Change in Remifentanil Plasma Concentration During Abdominal Laparoscopic Surgery

Sukhdorj, E.; Nakamura, R.; Saeki, N.; Yanabe, K.; Kutluk, A.; Hirano, H.; Hirano, H.; Yoshizumi, M.; Tsuji, T.; Kawamoto, M.

doi: 10.1213/01.ane.0000492997.53664.ab
E Poster discussion: Technology

1Department of Anesthesiology and Critical Care, Graduate School of Biomedical and Health Sciences of Hiroshima University, Hiroshima city, Japan, 2College of Medical Engineering Technology, Xinjiang Medical University, Urumqi, China, 3College of Medical Engineering Technology, Hiroshima University, Higashi-Hiroshima, 4Department of Cardiovascular Physiology and Medicine, Graduate School of Medicine, Hiroshima University, Hiroshima city, Japan

Background & Objectives: For determining stress response during general anesthesia to judge the adequacy of analgesia, various symptoms, such as heart rate, blood pressure, and muscle tension, are used by clinicians, though a continuous useful measurement method remains to be established. We developed a novel arterial mechanical impedance monitoring value to indicate peripheral arterial stiffness, termed K, which is derived from blood flow force and arterial radius. We evaluated the ability of K to detect changes in the intensity of nociceptive stimulation.

Materials & Methods: Following approval from our institutional ethical review board, 30 patients scheduled to undergo a laparoscopic colectomy procedure were enrolled. During the operation, electrocardiogram findings, invasive left radial arterial blood pressure, and photo-plethysmogram amplitude at the left thumb were simultaneously measured at a sampling rate of 125 Hz using a bedside monitor (BSS-9800, NIHON KOHDEN, Tokyo, Japan) and entered into a computer. K values were calculated in real time. The patients received 3 different effect site concentrations (2, 4, 6 ng/ml) of remifentanil at 3 times during the study period. The measured values of K during the 4 ng/ml administration were used as control values (Kcontrol). K values obtained during the 6 ng/ml administration (K6ng) were normalized by dividing K6ng by Kcontrol, while those obtained during the 2 ng/ml administration (K2ng) were normalized by dividing K2ng by Kcontrol. To compare the response of K for different remifentanil concentrations, we used the normalized K2ng (nK2ng) and normalized K6ng (nK6ng) values. A paired t-test was employed for statistical analysis and the level of significance was set at P<0.05.

Results: The highest K value for remifentanil effect-site concentration was observed during the 2 ng/ml administration, while the lowest was observed during the 6 ng/ml administration (K2ng: 35.9±25.6 mmHg/%, Kcontrol: 25.0±17.9 mmHg/%, K6ng: 20.0±15.7 mmHg/%). Furthermore, nK2ng showed a significantly higher response than nK6ng (1.56±0.95 vs. 0.84±0.28, P<0.0001).



Conclusion: The response of K was significantly different between the high and low concentrations of remifentanil. Our results show that a change in K reflects the change in intensity of surgical nociceptive stimulus during general anesthesia, indicating its use as an indicator of nociceptive stimulation.

Disclosure of Interest: None declared

© 2016 International Anesthesia Research Society