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Biomedical subjects

G Barber

Publications and source records attributed to G Barber.

47 records · Page 3Linked to original sources
PubMed1985

Statistical prediction of cardiac risk in patients who undergo vascular surgery.

Since August 1982, an extensive computerized data base has been developed on all patients admitted to the Division of Vascular Surgery at the Ottawa Civic Hospital. For each patient, 180 variables are recorded, including information about preoperative risk factors and postoperative complications. Since cardiac complications are a major cause of mortality and morbidity, the data file has been used to study postoperative cardiac complications in patients who undergo arterial reconstructive operations. Between August 1982 and December 1983, 353 artery repairs were performed, excluding ruptured aneurysms. Cardiac complications developed following surgery in 56 patients. Risk factors were initially studied using contingency table analysis. Four of these factors were found to be significant: electrocardiographic evidence of previous myocardial infarction (p = 0.0003), nonspecific ST-segment changes (p = 0.0007), New York Heart Association classification of symptoms (p = 0.0003) and age (p = 0.01). A further statistical study was based upon multiple logistic regression. The authors believe that the identification of a high-risk group, using these criteria, is helpful in selecting patients for intensive preoperative investigation, including coronary arteriography.

Age Factors↗
PubMed1984

Surgical repair of univentricular heart (double inlet left ventricle) with obstructed anterior subaortic outlet chamber.

The results of operation in all patients with univentricular heart and an obstructed anterior subaortic outlet chamber who were operated on utilizing extracorporeal circulation at the Mayo Clinic from 1973 through 1983 were reviewed. Ten of the 18 patients died during the immediate postoperative period and there was one late death. Factors significantly related to operative and immediate postoperative mortality were age at operation, cardiothoracic ratio on X-ray examination, degree of ST depression on electrocardiogram and pressure gradient across the outlet foramen at catheterization. Autopsy in eight cases revealed significant hypertrophy of ventricular myocardium and a small outlet foramen that was considered stenotic relative to either body surface area or aortic root area. The ventricular myocardium showed histologic changes of chronic ischemia that predated the surgical procedure.

Adolescent↗
PubMed1980

The production and generalization of large-magnitude heart rate deceleration by contingently faded biofeedback.

Eight subjects were taught to decrease their heart rates via biofeedback training. Four of these received contingently faded, beat-by-beat analogue feedback and contingent reinforcement each time their performance met a specified and adjusting criterion. The other four received continuous, beat-by-beat analogue feedback, but not the contingent reinforcement. Subjects in the two groups were yoked to ensure equal densities of reinforcement. Subjects in the first group were asked to decrease heart rates 15% from baseline and were then trained using only 75%, 50% and 25% of beat-by-beat feedback. It was hypothesized that the immediate reinforcement of appropriate behavior and the contingent fading (following mastery) of feedback would aid in the generalization of the response. Following completion of all criterion steps or 10 training sessions, whichever came first, all subjects were tested with no feedback and no contingent reinforcement. The group receiving contingently faded feedback training showed a significantly greater heart rate decrease in the training sessions and also the test session. These results were interpreted as indicating that biofeedback can be conceptualized as an operant conditioning paradigm, and that the use of operant techniques may help subjects produce clinically significant changes.

Biofeedback, Psychology↗
PubMed1979

Pattern discrimination and visuomotor behavior following rotation of one or both eyes in kittens and in adult cats.

Sixteen cats, each of which had one or both eyes rotated at the time of natural eye opening (group K), were tested for visuomotor behavior and for learning and interocular transfer of two-choice visual discriminations. Their behavior was compared to that of two cats given monocular rotations in adulthood (group A) and to two normal controls (group N). These animals were all reared in the same colony. All cats, including those with monocular rotations up to 180 degrees and those with binocular rotations up to 80 degrees in each eye, showed good visuomotor behavior when using the rotated eye (i.e., with the normal eye covered). Both the group K and group A animals showed comparable visuomotor adaptation. All animals except those with monocular rotations of 180 degrees were able to learn several oriented pattern discriminations and showed considerable though incomplete interocular transfer of such information. The three animals with 180 degrees rotations were able to learn brightness, but not pattern discriminations. Seven further animals with large rotations were used for histological studies of the retina and primary visual pathways. Areas of reduced ganglion cell density were not observed in whole mounts of the retinae, nor were regions of reduced transport of 3H-proline from the retina to the lateral geniculate nuclei or superior colliculi detectable from autoradiographs.

Animals↗
PubMed1979

Bacteriologic monitoring in abdominal aortic surgery.

In patients who undergo abdominal aortic operations, cultures have been recommended perioperatively to identify potential sources of graft infection. Bacteriologic monitoring was done in a group of patients receiving antibiotics prophylactically. Of 197 bowel bag cultures, 28 (14.2%) demonsrated small numbers of bacteria, usually Staphylococcus epidermidis, while of 31 aneurysm wall cultures, 7 (22.6%) grew bacteria. Four (6.6%) of 60 urine cultures done preoperatively indicated a significant bacteriuria, necessitating postponement of elective operations. Twenty-eight (46%) of 61 wounds revealed organisms of low pathogenicity, none of which caused overt infection. While the majority of 63 nasal cultures grew bacteria, this result did not influence the management of any patient. Eleven graft infections occurred in 517 abdominal aortic grafts inserted between 1967 and 1977. In three patients, infection was already present at the time of emergency operation while in another three, infections occurred subsequently, due to paraprosthetic-enteric fistulas in two and septicemia secondary to an operation on the genitourinary tract in the third. In the remaining five patients, no cause for infection was identified. Thus, no bowel bag culture and only one aneurysm wall culture was useful. This study has failed to demonstrate the value of routine cultures perioperatively in patients who undergo abdominal aortic operations.

Anti-Bacterial Agents↗