Hiroko Tanabe

Pituitary apoplexy during general anesthesia in beach chair position for shoulder joint arthroplasty.

Pituitary apoplexy is a rare but potentially life-threatening clinical syndrome caused by the sudden enlargement of pituitary adenoma secondary to infarction and/or hemorrhage. It may be the first presentation of previously undiagnosed pituitary adenoma. Although various precipitating factors of pituitary apoplexy are indicated, the pathogenesis remains unknown. In this report, we describe for the first time a case of pituitary apoplexy developed explicitly during general anesthesia supplemented with interscalene brachial plexus block in beach chair or barbershop position for shoulder joint arthroplasty.

The impact of remifentanil on incidence and severity of postoperative nausea and vomiting in a university hospital-based ambulatory surgery center: a retrospective observation study

Background Ambulatory surgery, including short-stay surgery, has become a common choice in clinical practice. For the success of ambulatory surgery, perioperative care with safe and effective anesthesia and postoperative analgesia, which can reduce the occurrence of postoperative nausea and vomiting (PONV), is essential. The effect of remifentanil on the occurrence and severity of PONV has not been thoroughly examined, particularly, in an ambulatory surgery setting. Here, we investigate whether remifentanil influences the occurrence and severity of PONV in a university hospital-based ambulatory unit. Methods We retrospectively analyzed a total of 1,765 cases of patients who had undergone general anesthesia at our ambulatory surgery unit. Parameters, such as occurrence and severity of nausea, vomiting or retching, use of antiemetic drugs, amount of postoperative analgesic and patient satisfaction, were extracted from the records and analyzed between the groups that received and not received remifentanil. Results Within 565 patients of the RF group, 39 patients (6.6%) experienced nausea, 7 patients (1.2%) experienced vomiting or retching, and 10 patients (1.8%) were given antiemetic; in addition, the maximum VAS value for nausea was 12.1 mm. In 1,200 patients of the non RF group, 102 patients (8.5%) experienced nausea, 19 patients (1.6%) experienced vomiting or retching, and 34 patients (2.8%) were given antiemetic, and the maximum VAS value was 13.2 mm. There were no statistically significant differences between the two groups. Conclusions Our results indicate that remifentanil did not increase the occurrence of PONV in patients within the ambulatory surgery unit.

Large postural fluctuations but unchanged postural sway dynamics during tiptoe standing compared to quiet standing

The purpose of this study was to detect the characteristics of center of pressure (COP) movement during tiptoe standing (TS) compared to quiet standing (QS). Eight healthy subjects were asked to perform QS and TS on a force platform. During standing, surface electromyograms (EMGs) were recorded from the soleus (SOL), flexor hallucis brevis (FHB), medial gastrocnemius (MG), lateral gastrocnemius (LG), and tibialis anterior (TA) muscles. The path length and rectangular area of the COP trajectory were significantly larger during TS than during QS. In contrast, irrespective of standing condition, the scaling coefficients in the short and long regions were above and below 0.5, respectively. The coherence spectrum between the COP and EMG from the SOL and FHB muscles was statistically significant during TS at frequencies up to 17 Hz, while that for the QS was only significant below 1 Hz. In conclusion, the control of COP movement during TS was similar to that during QS despite large COP fluctuations during TS. Our results suggest that unstable posture during TS is compensated for by the activities of the SOL and FHB muscles, which enhance postural control.

Effect of intermittent feedback control on robustness of human-like postural control system

Humans have to acquire postural robustness to maintain stability against internal and external perturbations. Human standing has been recently modelled using an intermittent feedback control. However, the causality inside of the closed-loop postural control system associated with the neural control strategy is still unknown. Here, we examined the effect of intermittent feedback control on postural robustness and of changes in active/passive components on joint coordinative structure. We implemented computer simulation of a quadruple inverted pendulum that is mechanically close to human tiptoe standing. We simulated three pairs of joint viscoelasticity and three choices of neural control strategies for each joint: intermittent, continuous, or passive control. We examined postural robustness for each parameter set by analysing the region of active feedback gain. We found intermittent control at the hip joint was necessary for model stabilisation and model parameters affected the robustness of the pendulum. Joint sways of the pendulum model were partially smaller than or similar to those of experimental data. In conclusion, intermittent feedback control was necessary for the stabilisation of the quadruple inverted pendulum. Also, postural robustness of human-like multi-link standing would be achieved by both passive joint viscoelasticity and neural joint control strategies.

Takotsubo cardiomyopathy during ambulatory anesthesia for bladder hydrodistension therapy -A case report-

Stress-induced cardiomyopathy, also referred to Takotsubo cardiomyopathy or apical ballooning syndrome presents in perioperative period. We demonstrated a case of Takotsubo cardiomyopathy recognized after general anesthesia for bladder hydrodistension therapy as ambulatory surgery, which we surmise was due to inadequate blockage of surgical stress and sympathetic discharge against noxious stimulus during ambulatory anesthesia.

Coptidis Rhizoma Water Extract Stimulates 5′-AMP-Activated Protein Kinase in Rat Skeletal Muscle

Aim Coptidis Rhizoma (CR), the dried rhizomes of Asian herbs (including Coptis chinensis Franch), has been used to treat diabetes mellitus for thousands of years. We explored the possibility that CR acts directly on skeletal muscle, the major organ responsible for glucose homeostasis, and activates 5′-AMP-activated protein kinase (AMPK), a signaling intermediary leading to metabolic enhancement of skeletal muscle.

Intermittent muscle activity in the feedback loop of postural control system during natural quiet standing

The origin of continual body oscillation during quiet standing is a neural-muscular-skeletal closed feedback loop system that includes insufficient joint stiffness and a time delay. Thus, muscle activity and joint oscillations are nonlinear during quiet standing, making it difficult to demonstrate the muscular-skeletal relationship experimentally. Here we experimentally revealed this relationship using intermittent control theory, in which non-actuation works to stabilize the skeletal system towards equilibrium. We found that leg muscles were activated/inactivated when the state point was located in the opposite/same direction as the direction of anatomical action, which was associated with joint torque actuating the body towards equilibrium. The derivative values of stability index defined in the phase space approximately 200 ms before muscle inactivation were also larger than those before activation for some muscles. These results indicate that bipedal standing might be achieved by monitoring the rate of change of stability/instability components and generating joint torque to stabilize the body. In conclusion, muscles are likely to activate in an event-driven manner during quiet standing and a possible metric for on/off switching is SI dot, and our methodology of EMG processing could allows us to extract such event-driven intermittent muscle activities.

Joint Coordination and Muscle Activities of Ballet Dancers During Tiptoe Standing

We aimed to investigate joint coordination of lower limbs in dancers during tiptoe standing and the relationship between joint coordination and muscle coactivation. Seven female ballet dancers performed tiptoe standing with six leg positions (fi e classical dance positions and one modern dance position) for 10 s. The kinematic data of the metatarsophalangeal (MP), ankle, knee, and hip joints was collected, and surface electromyography (EMG) of over 13 lower limb muscles was conducted. Principal component analysis was performed to determine joint coordination. MP-ankle and ankle-knee had in-phase coordination, whereas knee-hip showed anti-phase coordination in the sagittal plane. In addition, most EMG-EMG coherence around the MP and ankle joints was significant up to 50 Hz when these two joints swayed with in-phase. This suggests that different joint coordination patterns are associated with neural processing related to different muscle coactivation patterns. In conclusion, ballet dancers showed in-phase coordination from the MP to knee joints, which was associated with muscle coactivation to a higher frequency domain (up to 50 Hz) in comparison with anti-phase coordination.

Role of heel lifting in standing balance recovery: A simulation study

Although lifting the heels has frequently been observed during balance recovery, the function of this movement has generally been overlooked. The present study aimed to investigate the functional role of heel lifting during regaining balance from a perturbed state. Computer simulation was employed to objectively examine the effect of allowing/constraining heel lifting on balance performance. The human model consisted of 3 rigid body segments connected by frictionless joints. Movements were driven by joint torques depending on current joint angle, angular velocity, and activation level. Starting from forward-inclined and static straight-body postures, the optimization goal was to recover balance effectively (so that ground projection of the mass center returned to the inside of the base of support) and efficiently by adjusting ankle and hip joint activation levels. Allowing/constraining heel lifting resulted in virtually identical movements when balance was mildly perturbed at the smallest lean angle (8°). At larger lean angles (8.5° and 9°), heel lifting assisted balance recovery more evidently with larger joint movements. Partial and altered timings of ankle/hip torque activation due to constraining heel lifting reduced linear and angular momentum generation for avoiding forward falling, and resulted in hindered balancing performance.

Switching Adaptability in Human-Inspired Sidesteps: A Minimal Model

Humans can adapt to abruptly changing situations by coordinating redundant components, even in bipedality. Conventional adaptability has been reproduced by various computational approaches, such as optimal control, neural oscillator, and reinforcement learning; however, the adaptability in bipedal locomotion necessary for biological and social activities, such as unpredicted direction change in chase-and-escape, is unknown due to the dynamically unstable multi-link closed-loop system. Here we propose a switching adaptation model for performing bipedal locomotion by improving autonomous distributed control, where autonomous actuators interact without central control and switch the roles for propulsion, balancing, and leg swing. Our switching mobility model achieved direction change at any time using only three actuators, although it showed higher motor costs than comparable models without direction change. Our method of evaluating such adaptation at any time should be utilized as a prerequisite for understanding universal motor control. The proposed algorithm may simply explain and predict the adaptation mechanism in human bipedality to coordinate the actuator functions within and between limbs.