title: Servo-controlled hind-limb electrical stimulation for short-term arterial pressure control.
abstract: BACKGROUND
  Autonomic neural intervention is a promising tool for modulating the circulatory system thereby treating some cardiovascular diseases.
  
  
  RESULTS
  In 8 pentobarbital-anesthetized cats, it was examined whether the arterial pressure (AP) could be controlled by acupuncture-like hind-limb electrical stimulation (HES). With a 0.5-ms pulse width, HES monotonically reduced AP as the stimulus current increased from 1 to 5 mA, suggesting that the stimulus current could be a primary control variable. In contrast, the depressor effect of HES showed a nadir approximately 10 Hz in the frequency range between 1 and 100 Hz. Dynamic characteristics of the AP response to HES approximated a second-order low-pass filter with dead time (gain: -10.2 +/- 1.6 mmHg/mA, natural frequency: 0.040 +/- 0.004 Hz, damping ratio 1.80 +/- 0.24, dead time: 1.38 +/- 0.13 s, mean +/- SE). Based on these dynamic characteristics, a servo-controlled HES system was developed. When a target AP value was set at 20 mmHg below the baseline AP, the time required for the AP response to reach 90% of the target level was 38 +/- 10 s. The steady-state error between the measured and target AP values was 1.3 +/- 0.1 mmHg.
  
  
  CONCLUSIONS
  Autonomic neural intervention by acupuncture-like HES might provide an additional modality to quantitatively control the circulatory system.
authors.affiliation: Department of Cardiovascular Dynamics, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, Suita, Japan. torukawa@res.ncvc.gov.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Kawada
authors.forename: Shuji
authors.initials: S
authors.lastname: Shimizu
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Shishido
authors.forename: Atsunori
authors.initials: A
authors.lastname: Kamiya
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Sunagawa
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugimachi
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D001701:Bionics; D001794:Blood Pressure; D001808:Blood Vessels / Q000294:innervation*; D002415:Cats; D015671:Electroacupuncture; D006614:Hindlimb; D008955:Models, Cardiovascular; D018482:Muscle, Skeletal / Q000098:blood supply*; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors