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Biomedical subjects

R B Shepard

Publications and source records attributed to R B Shepard.

27 records · Page 2Linked to original sources
PubMed1982

Effects of various operations on the electrical activity of the human stomach recorded during the postoperative recovery period.

This study attempts to characterize any changes occurring in the human gastric control electrical rhythm (CER), following a variety of gastric surgical procedures. Pairs of electrodes were implanted in selected specific sites on the stomachs of 57 patients undergoing either antrectomy and vagotomy, proximal gastric vagotomy (PGV), vagotomy and drainage, gastric resection without vagotomy, or fundoplication. Five patients undergoing nongastric operations served as controls. After operation recordings were obtained with differential preamplifiers, an oscilloscope, and a dual-channel tape recorder. An electrical signal compatible with a CER was found almost always in the distal body or antrum, regardless of whether vagotomy was performed. In contrast, a CER was found only occasionally in the fundus, and was never found following PGV. Although there was a difference in the frequency of occurrence of fundic CER in patients with and without vagotomy, it was not statistically significant (p = 0.0668). Patients with prolonged postoperative convalescence because of gastric atony were compared with patients with normal postoperative courses regarding the presence or absence of CER in the gastric antrum or fundus. A statistically significant relationship between abnormal gastric motility and absence of CER was not established.

Eating↗
PubMed1982

Autocorrelation, cross correlation and coherence analyses of the electrical activity of the human stomach in the postoperative period.

Electrical potentials generated by the stomach have been well categorized. They vary in amplitude, shape, frequency and time relationships and may be contaminated by electrical activity from other organs. In addition to visual observation, this investigation used methods of autocorrelation and cross correlation, spectral analysis and coherence determinations to refine and numerically characterize gastric electrical potentials. Bipolar Teflon coated electrode wires were brought out through the abdominal wall in six patients, four of whom underwent fundoplication, one of whom underwent cholecystectomy and one of whom underwent portacaval shunt. Recordings were obtained until the ninth postoperative day using differential preamplifiers, an oscilloscope and a dual channel tape recorder. Oscilloscope displays were photographed, and the outputs of the tape recorder were filtered in the analog mode. Similar recordings were also obtained postoperatively in a patient with gastric stasis, and a surface electrode was used to record the gastric electrical activity of a normal volunteer. The propagation time, electrical control activity frequencies and bioelectrical dependence or independence between the two measuring sites were clearly differentiated by these methods. This method offers a safe and feasible way of recording and analyzing the electrical activity of the human stomach in the postoperative period with statistically specified reliability. This is accomplished through temporarily implanted wires, and, potentially, from the surface of the body, even during electrical interference.

Electrodes, Implanted↗