Stimulation of abdominal and upper thoracic muscles with surface electrodes for respiration and cough: Acute studies in adult canines.

OBJECTIVE: To optimize maximal respiratory responses with surface stimulation over abdominal and upper thorax muscles and using a 12-Channel Neuroprosthetic Platform. METHODS: Following instrumentation, six anesthetized adult canines were hyperventilated sufficiently to produce respiratory apnea. Six abdominal tests optimized electrode arrangements and stimulation parameters using bipolar sets of 4.5 cm square electrodes. Tests in the upper thorax optimized electrode locations, and forelimb moment was limited to slight-to-moderate. During combined muscle stimulation tests, the upper thoracic was followed immediately by abdominal stimulation. Finally, a model of glottal closure for cough was conducted with the goal of increased peak expiratory flow. RESULTS: Optimized stimulation of abdominal muscles included three sets of bilateral surface electrodes located 4.5 cm dorsal to the lateral line and from the 8th intercostal space to caudal to the 13th rib, 80 or 100 mA current, and 50 Hz stimulation frequency. The maximal expired volume was 343 ± 23 ml (n=3). Optimized upper thorax stimulation included a single bilateral set of electrodes located over the 2nd interspace, 60 to 80 mA, and 50 Hz. The maximal inspired volume was 304 ± 54 ml (n=4). Sequential stimulation of the two muscles increased the volume to 600 ± 152 ml (n=2), and the glottal closure maneuver increased the flow. CONCLUSIONS: Studies in an adult canine model identified optimal surface stimulation methods for upper thorax and abdominal muscles to induce sufficient volumes for ventilation and cough. Further study with this neuroprosthetic platform is warranted.

Stimulating multiple respiratory muscles with intramuscular Permaloc electrodes.

OBJECTIVE: To test the feasibility of implanting intramuscular electrodes (Permaloc, Synapse Biomedical Inc, Oberlin OH) with self-securing polypropylene anchors to stimulate upper-intercostal and abdominal muscles plus the diaphragm. METHODS/RESULTS: In 6 anesthetized dogs, 12 Permaloc electrodes were implanted in the 3 respiratory muscles (4 in each muscle group). Tidal volume with diaphragmatic stimulation was 310 +/- 38 mL (mean +/- SE); with upper intercostal stimulation, it was 68 +/- 18 mL; and with combined diaphragm intercostal stimulation, it was 438 +/- 78 mL. By study design, stimulation in the upper intercostal muscles was limited to not more than slight/moderate contraction of the serratus and latissimus muscles overlying the ribs. Abdominal muscle stimulation produced exhaled volumes of 38 +/- 20 mL (this stimulation was limited by the maximal output of the stimulator of 25 milliamperes). Combined diaphragm intercostal stimulation followed by abdominal muscle stimulation increased exhaled volumes from 312 +/- 31 mL to 486 +/- 58 mL (P = 0.024). CONCLUSIONS: Permaloc electrodes can be successfully implanted in upper intercostal and abdominal muscles in addition to the diaphragm. Combined diaphragm intercostal stimulation followed by abdominal muscle stimulation increased the exhaled volumes recorded with diaphragmatic stimulation alone.

The use of honey as a topical dressing to treat a large, devitalized wound in a stumptail macaque (Macaca arctoides).

There are many reasons wounds are managed as open wounds rather than by primary closure. Indications include gross contamination, infection, and skin loss leading to insufficient adjacent tissue for wound closure. The most common method of managing an open wound is with wet-to-dry dressings. Wet-to-dry dressings provide mechanical debridement and promote the movement of viscous exudates away from the wound. Wet-to-dry bandages ideally are changed every 12 to 24 h. For nonhuman primates, it is desirable to develop wound management techniques that limit animal handling for bandage changes and thus the frequency of sedation. Anecdotal reports on the use of honey to treat wounds date back to 2000 B.C. Recently, scientific inquiries have found merit to these reports. Honey accelerates healing because of its direct effects on tissue and antibacterial properties. In addition, dressings with honey can be changed relatively infrequently. Honey decreases inflammatory edema, hastens sloughing of devitalized tissue, attracts macrophages which cleanse the wound, provides a local cellular energy source, and protectively covers the wound. A high osmolarity, acidity, and hydrogen peroxide content confer honey with antibacterial properties. Here we describe the use of honey to manage a bite wound in a stumptail macaque (Macaca arctoides). The wound healed rapidly: after 2 weeks of treatment, there was markedly less exudate and no necrotic tissue. This report describes how honey may be helpful in the management of open wounds in nonhuman primates by minimizing the need for sedation for bandage changes.