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Biomedical subjects

J F Hogan

Publications and source records attributed to J F Hogan.

7 recordsLinked to original sources
PubMed1992

Comparison of 180-degree and 360-degree skeletal muscle nerve cuff electrodes.

Use of skeletal muscle for cardiac augmentation is a promising technique for treatment of end-stage cardiac failure. An electrode woven through the latissimus dorsi that recruits nearby nerve fibers is commonly used to pace skeletal muscles both in clinical practice and in the laboratory. A proximally placed nerve cuff electrode offers potential advantages in improved recruitment of muscle fibers and low threshold for stimulation. We tested the effectiveness of a nerve cuff electrode passed directly about the proximal thoracodorsal nerve. Our report looks at the efficacy of nerve cuff electrode stimulation and compares electrical and histologic characteristics of a 180-degree wrap of the thoracodorsal nerve to a 360-degree wrap in dogs over 3 months. Threshold voltage at the commonly used pulse width of 200 microseconds was typically in the range of 400 to 600 mV for each electrode after 3 months. Statistical analysis revealed no significant difference (p < 0.05) in threshold voltage or current between the 180-degree and 360-degree nerve cuff electrode either at acute evaluation or after 3 months. Even contraction of latissimus dorsi was achieved with all implants. Adenosine triphosphatase staining revealed 100% conversion of type II to type I fibers in all stimulated muscles. Histologic examination of the thoracodorsal nerve and latissimus dorsi muscle revealed no abnormalities grossly or by light microscopy. Thus, a carefully applied nerve cuff electrode is an atraumatic, effective method for skeletal muscle stimulation. The 180-degree and 360-degree nerve cuff configurations are equally effective.

Adenosine Triphosphatases↗
PubMed1977

A demand diaphragm pacemaker.

A PACO2 feedback control system (demand diaphragm pacemaker) was developed in this laboratory to maintain homeostasis during diaphragm pacing, thus avoiding hypo- or hyperventilation. Application of this system to the research animal made it possible to maintain blood gases and pH within normal limits for up to 15 hrs. Oscillation between maximal tidal volume and apnea that occurred with the amplitude feedback control was eliminated by using a rate feedback control. A possible additional benefit of a feedback control system is the reduction of current applied to the nerve as compared to that in asynchronous pacing, thereby minimizing the fatigue phenomenon.

Animals↗
PubMed1977

Diaphragm pacing. Evaluation of current waveforms for effective ventilation.

To evaluate the effectiveness of the configuration of the stimulating waveform on diaphragm pacing, we evaluated several different current forms: UDC-bipolar, UDC-monopolar cathodal, UDC-monopolar anodal, and ABDC. During stimulation with a pulse interval of 37 msec., a decrease in tidal volume was observed during the initial 30 hours with UDC-bipolar and UDC-monopolar anodal waveforms. Both UDC-monopolar cathodal and ABDC stimulation maintained the initial effectiveness for 6 hours. The decrease in tidal volume of UDC-monopolar anodal closely paralleled that of UDC-bipolar stimulation. Decreasing the pulse interval to 20 msec. caused a decrease in tidal volume with both UDC-monopolar cathodal and ABDC waveforms. Arterial oxygen tension (PaO2) in these experiments decreased to about 60 mm. Hg soon after the onset of unilateral diaphragm pacing. The concomitant decrease in tidal volume seen with UDC-bipolar stimulation could be avoided through the administration of oxygen to keep the animal's PaO2 about 100 mm. Hg. The amplitude of the evoked diaphragmatic action potentials decreased significantly under hypoxemia and returned to normal with hyperoxygenation. From these short-term experiments, our findings indicate that waveform configuration does influence the time of onset of diaphragm fatigue due to either an neuromuscular junction. Further, hypoxemia accelerates the occurrence of fatigue.

Acetylcholine↗
PubMed1976

Long-term ventilatory support by diaphragm pacing in quadriplegia.

Thirty-seven quadriplegic patients with respiratory paralysis were treated by electrical stimulation of the phrenic nerves to pace the diaphragm. Full-time ventilatory support by diaphragm pacing was accomplished in 13 patients. At least half-time support was achieved in 10 others. There were two deaths unrelated to pacing in these two groups. Fourteen patients could not be paced satisfactorily, and 8 of these patients died, most of them from respiratory infections. The average time the 13 patients on total ventilatory support have had bilateral diaphragm pacemakers is 26 months. The longest is 60 months. Many of these patients are out of the hospital and several are in school or working. Injury to the phrenic nerves either by the initial trauma to the cervical cord or during operation for implantation of the nerve cuff was the most significant complication. Nerve damage from prolonged electrical stimulation has not been a problem thus far. A description of the pacemaker, the technique of its implantation, and the pacing schedule are reported.

Adolescent↗