L. Ilyes

Voluntary control of an ileal pouch by coordinated electrical stimulation. A pilot study in the dog.

Heal reservoirs were constructed in four dogs under general anesthesia and stimulated by means of a constant current generator that produced pulse trains at frequencies between 6 Hz and 1.67 kHz. Stimulation at 6 Hz with 50 ms pulses between amplitudes of 15 and 25 mA uniformly produced pouch contraction and reservoir emptying. Stimulation at other frequencies did not cause pouch emptying although pressure increases were sometimes observed. Such electrical stimulation may be useful for voluntary control of intestinal reservoirs when used as replacement for urinary bladder or colon. The mechanism by which the intestinal contraction is preduced appears to be different than that produced by slow wave pacing

Artificial reflex arc: A potential solution for chronic aspiration: II. A canine study based on a laryngeal prosthesis†

Long‐term and repeated aspiration can result in pneumonia and eventually death. To avoid current techniques which divert or close off the incompetent larynx, the authors have recently described an artificial reflex arc (ARA), in hopes of providing a dynamic solution to this problem. With this concept, a segment of skin surface with intact sensory innervation is implanted into the pharynx in the path of the food bolus. Resulting neural impulses would be detected by a perineural electrode and then channeled to both recurrent laryngeal nerves via an electronic pacemaker to cause vocal fold adduction at the critical time during swallowing. A pilot study using a tubed cervical cutaneous surface has yielded promising results in the canine. In this current study, an alternate means for information pickup based upon use of a miniature strain gage is presented. Mechanical stimulation of the hypopharynx using this “sensory” detector resulted in synchronous laryngeal adduction of the vocal folds, as documented graphically and on videotape.

Direct Nerve Implantation Vs. Nerve-Muscle Pedicle: A Comparative Study of Reinnervation in the Rabbit

To determine the optimal method for reinnervation of the paralyzed head and neck musculature, we compared direct muscular nerve implants (DNI) with nerve-muscle pedicles (NMP) in rabbits. In 25 anesthetized animals, one ansa hypoglossi nerve was cut. Five animals sensed as controls and two groups of 10 each received cross-over DNIs or NMP from one sternothyroid to the contralateral sternohyoid muscle. The transplanted nerves of animals that survived long enough for neurotization to occur (8 DNIs, 5 NMPs) were stimulated with 3 to 10 mA. 0.05 msec pulse trains to obtain force curves from corresponding straps. Fiber diameters and areas were calculated on muscles harvested before the animals were killed. There was a nonsignificant trend toward stronger contraction in the NMP group, but NMP fibers were significantly larger than those in DNI and control groups (p < 0.001).

Die Rekation des Dünndarms auf transmurale Elektrostimulation beim nüchternen und gefütterten Tier

ZusammenfassungUm zu prüfen, ob die Reaktion des Dünndarms auf hochfrequente Elektrostimulation von der Nahrungsaufnahme beeinflußt wird, wurden nach einer Serie von Akutversuchen bei 2 Hunden eine Jejunumschlinge und bei weiteren 2 ein Jejunumpouch mit Elektroden und Druckmeßsonden bestückt und am wachen Tier im chronischen Versuch untersucht. 500-μsec-910-Hz-25-mA-Ströme erhöhten den Druck in der Jejunumschlinge um 26±22 mm Hg (n=10) beim nüchternen und um 21±23 mm Hg (n=9) beim gefütterten Tier. Der Pouch war beim gefütterten Tier schwieriger zu stimulieren. Durch Elektrostimulation ist es möglich, am wachen Tier Dünndarmkontraktionen auszulösen, welche nur im Falle des Dünndarmpouches vom Status der Nahrungsaufnahme beeinflußt werden.SummaryTo prove whether food intake influences the reaction of the small intestine to electrostimulation 4 dogs were chronically investigated after a series of acute studies. Stimulation with 500 μsec 910 Hz 25 mA currents raised the intraluminal pressure by 26±33 mm Hg in the jejunal loop in the fasted and by 21±23 mm Hg in the fed animal. Pouches were difficult to stimulate in fed dogs. Intestinal loops and pouches may be contracted by electrostimulation in awake animals. Feeding inhibits the reaction in intestinal reservoirs.

Elektrostimulation von Ileum und Jejunumreservoiren im akuten und chronischen Experiment

SummaryVoluntary control of the motility of intestinal reservoirs may be used to improve evacuation and continence. In 4 dogs a U-shaped jejunum pouch and in another 4 an ileum pouch was constructed and instrumented with stimulating and EMG electrodes and pressure lines. In the acute experiments jejunum pouch stimulation with 200 μs 1.67 kHz 30 mA increased the intrapouch pressure by 38 ± 4 mm Hg (n = 6) and 500 μs 910 Hz 25 mA by 60 ± 5 mm Hg (n = 3). The pressure increase in the awake animals was consistently lower (200 μs 4±6 mm Hg,n=9; 500 μs 25±17,n= 11). The ileum pouch responded with a 37 ± 10 mm Hg pressure increase (n=9) to 50 ms 6 Hz 20 mA pulse trains. Ileum pouches could not be stimulated in the awake animal due to contraction of the abdominal wall. Electrostimulation may be used to contract and evacuate intestinal reservoirs but additional drug therapy or autonomic nerve stimulation will be necessary to lower the thresholds especially for ileum stimulation in the awake animal.ZusammenfassungDie Kontrolle der Motorik von intestinalen Reservoiren kann zur Verbesserung der Entleerung und der Kontinenz beitragen. Bei 4 Tieren wurde ein U-förmiger Jejunumpouch und bei weiteren 4 ein Ileumpouch gebildet und mit Stimulationselektroden und Druckkathetern instrumentiert. Die akute Stimulation des Jejunumpouches mit 30 mA 200 μs 1,67 kHz erhöhte den Innen druck um 38 ± 4 mm Hg (n = 6). Eine Stimulation mit 500 μs 910 Hz 25 mA ergab eine Druckerhöhung von 60 ± 5 mm Hg. Bei 11 Messungen an zwei chronisch instrumentierten Tieren erhöhte dieselbe Stimulation den Druck um 25 ± 17 mm Hg. Die 200 μs Kombination zeigte variable Ergebnisse. Im Ileumpouch konnte im Akutversuch mit 50 ms 6 Hz 20 mA (n = 9) der Druck um 37 ± 10 mm Hg gesteigert werden. Diese Stimulationsform wurde vom wachen Tier nicht toleriert. Eine Elektrostimulation von Dünndarmreservoiren ist prinzipiell möglich, die Variabilität der Reaktion muß durch adjuvante Pharmacotherapie oder durch Stimulation vegetativer Nerven kontrolliert werden.