Abstract 5428: Transcutaneous Bionic Baroreflex System Is Widely Applicable For Preventing Severe Orthostatic Hypotension In Patients With Cervical Cord Injury
Background: We proposed an artificial baroreflex system (bionic baroreflex system: BBS) capable of feedback control of arterial pressure (AP) (Circulation 1999, 2002, 2004). Using BBS, in 2007, we reported a case where we prevented severe orthostatic hypotension in “a patient” with cervical cord injury. It remained unknown, however, if the bionic mechanism is widely applicable for other patients with cervical cord injury in preventing orthostatic hypotension.
Methods and Results: In 8 patients with cervical cord injury who have been suffering from severe orthostatic hypotension, we scanned the body surface and successfully identified the region in every patient capable of increasing AP in response to electrical stimulation. We then stimulated the region with current-modulated electrical pulse-train at 10 Hz with a duty cycle of 0.25, identified the transfer function from the stimulation to AP, and parameterized the respective transfer function (gain = 1.95±0.62 mmHg/mA, time-constant = 75.3±13.1 sec, lag = 0.39±0.37 sec). Using those parameters, we developed a feedback regulator of BBS to control AP. Orthostatic stress decreased mean AP by 30.7±2.9 mmHg. Activation of BBS restored AP to a preset-target value (73.6±6.4 mmHg) by 50% at 34.6±12.1 sec, and by 90% at 60.0±18.3 sec. The regulated AP remains at the target level at least for 10 minutes (Figure⇓).
Conclusion: The transcutaneous BBS is noninvasive and widely applicable for stabilizing AP in patients with cervical cord injury with serious orthostatic hypotension. The oriental wisdom, i.e., making the use of a skin region as a window to modulate the autonomic system, revitalizes patients with central baroreflex failure.