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J C Kerr

Publications and source records attributed to J C Kerr.

At least 37 records · Page 2Linked to original sources
PubMed1983

A critical analysis of clerkship grading procedures.

Rating of clinical performance and examination scores are employed to establish the final grade of students undertaking the surgical clerkship. This retrospective study was undertaken to determine whether there is a correlation between these two grading procedures in evaluating students. Grades for clinical performance and the scores obtained on the written examination-either intramural (IM) or extramural (EM)-by each student for 20 recent consecutive 12-week surgical clerkship rotations were tabulated and the correlation (regression) coefficients of the two grading systems calculated in each rotation. By means of a questionnaire, grading methods employed in 60 randomly selected US medical school surgical departments were requested (55 responded). Correlation coefficients indicate that there is no statistical correlation between the grades of the clinical performance and the written examination in the majority of rotations (80 percent IM and 70 percent EM).GRADING PROCEDURES USED TO DERIVE THE FINAL GRADE AND THE MEANS OF REPORTING IT IN OTHER MEDICAL SCHOOLS ARE AS FOLLOWS: 41 percent (23/55) used the clinical performance and written examination; 38 percent (21/55) used the clinical performance, written examination, and oral examination; and 20 percent (9/55) used the clinical performance only. For the final grade, 91 percent (50/55) subscribed to honors, pass, and fail categories and 9 percent (5/55) preferred a numerical grade.

Clinical Clerkship↗
PubMed1982

Clinical use of vasopressin in the management of bleeding esophageal varices.

Vasopressin has been used for 25 years to control bleeding from esophageal varices. Its efficacy is believed to be due to a direct vasoconstrictor activity on splanchnic arterioles and precapillary sphincters, with secondary reduction in portal venous blood flow and pressure. While it has been administered by both the intra-arterial and intravenous routes, the latter has gained favor in the light of laboratory and clinical investigations. The most common complications are cardiovascular, and bradycardia is an early sign of toxicity; adverse effects may be avoided with simultaneous infusion of isoproterenol. Vasopressin has not been shown to prolong survival from esophageal bleeding. It is effective in controlling upper gastrointestinal hemorrhage and is commonly viewed as a means of buying time to prepare the patient for shunt surgery. Vasopressin infusion may reduce both operation time and blood loss during shunt surgery. New analogs of vasopressin presently under investigation may facilitate its administration and reduce morbidity.

Cardiovascular Diseases↗
PubMed1982

Differential hyperemic responses following femoral arterial and thigh cuff occlusion in the canine hindlimb.

The hyperemic response following arterial reconstruction is variable. To further evaluate this response, arterial blood flows in the canine hindlimb were compared following isolated femoral arterial occlusion and after thigh cuff tourniquet occlusion, which also obstructs collateral circulation. Arterial occlusion and tourniquet occlusion produced significant (P less than 0.05) increases in femoral arterial flow after all intervals of occlusion, except following 30 minutes of isolated arterial occlusion. Isolated arterial occlusion and tourniquet occlusion produced comparable hyperemic responses through five minutes of occlusion. However, tourniquet occlusion produced a significantly greater increase (P less than 0.05) in femoral flow when occlusions exceeded five minutes. These data suggest that the extent of collateralization may moderate the postobstructive hyperemic response following aortic and femoropopliteal reconstruction. The collateral recruitment during isolated arterial occlusion may be responsible for a diminished hyperemic response with time, while obstruction of the collateral circulation during tourniquet occlusion may result in a greater hyperemic response.

Animals↗
PubMed1981

Prostacyclin (epoprostenol): its effect on canine splanchnic blood flow during hemorrhagic shock.

Prostacyclin (epoprostenol, prostaglandin I2) is a vasodilator of the splanchnic circulation during normotensive states. To confirm the persistence of its effects after hemorrhagic shock, six anesthetized, previously splenectomized, adult mongrel dogs were subjected to hemorrhagic shock using a modified Wigger's technique in which a mean arterial pressure of 30 mm Hg was maintained until 25% of the shed blood spontaneously returned. The animals were randomly resuscitated with normal saline solution or a similar volume of saline solution containing prostacyclin. Organ blood flow was calculated by measuring the distribution of radioactively tagged microspheres. During shock, blood flows to the liver, small intestine, pancreas, and carcass were reduced. During a 60-minute infusion, prostacyclin selectively caused a significant increase in hepatic arterial blood flow. This improvement in arterial blood flow may prove beneficial in the clinical management of hemorrhagic shock.

Animals↗
PubMed1981

Adrenergic stimulation and blockade in colonic circulation of the rhesus monkey.

Adrenergic stimulation and blockade on inferior mesenteric arterial blood flow (Q) were measured in anesthetized rhesus monkeys. Control Q was 25 +/- 2 (mean +/- SE) ml/min; aortic and portal venous pressures were 121 +/- 5 and 6.5 +/- 1.0 mmHg. Calculated inferior mesenteric arterial resistance was 5.10 +/- 0.42 peripheral resistance units. Norepinephrine (N), 10(-3) to 1.0 microgram/kg intra-arterially, caused dose-dependent decreases in Q. Epinephrine (E) increased Q at 10(-3) microgram/kg in 60% of the animals studied and decreased Q at the higher doses (10(-2) to 1.0 microgram/kg). Isoproterenol (I) increased Q at all four doses studied. Ten-minute infusions of N and E (0.5 microgram x kg-1 x min-1) caused sustained decreases, and I caused sustained increases in Q. Autoregulatory escape was not observed. alpha-Adrenergic receptor blockade (phenoxybenzamine) attenuated the vasoconstrictor responses to N, but did not "reverse" the vasoconstrictor response to E (vasodilation). beta-adrenergic receptor blockade (propranolol) attenuated the vasodilator responses to I, but did not alter significantly the responses to E or N. These data indicate that in the monkey colonic circulation, alpha-adrenergic receptor stimulation causes vasoconstriction and beta-adrenergic receptor stimulation causes vasodilation.

Animals↗
PubMed1978

Vasopressin: route of administration and effects on canine hepatic and superior mesenteric arterial blood flows.

BLOOD FLOWS THROUGH THE CANINE HEPATIC (HBF) AND SUPERIOR MESENTERIC ARTERIES (MBF) WERE MEASURED WITH ELECTROMAGNETIC FLOWMETERS, DURING INFUSIONS OF VASOPRESSIN, BY THREE ROUTES OF ADMINISTRATION: 1) intra-hepatic-arterially (IHA), 2) intra-portal-venously (IPV) and 3) intra-systemic-venously (IV). Mean control HBF was 148 +/- 17 (S.E.) ml min(-1); MBF was 243 +/- 27 ml min(-1); aortic pressure (AP) was 126 +/- 3 mm Hg; portal venous pressure (PVP) was 8.8 +/- 1.0 mm Hg. Infusions of vasopressin, at a rate of 5 x 10(-3) units kg(-1) min(-1), IHA, reduced HBF significantly (p < .001) to 121 +/- 21 ml min(-1), within one minute. Flow returned to control, despite continued drug infusion; and at the end of the fifth minute of infusion, the value (134 +/- 21 ml min(-1)) was not significantly (p > .05) different from control. During the same infusion, MBF fell to 129 +/- 28 ml min(-1) (p < .001), by the sixth minute of the infusion and remained at this level for the duration of the infusion. AP increased to 137 +/- 13 mm Hg, by the sixth minute of the infusion and was sustained at this level for the duration of the infusion. PVP decreased to 7.0 +/- 1.0 mm Hg, by the tenth minute of the infusion. The responses to IPV vasopressin were indistinguishable from those following IHA vasopressin, with the exception that HBF was reduced to only 147 +/- 22 ml min(-1) (from a preinfusion control of 160 +/- 23 ml min(-1)), at one minute. HBF returned to control, despite continuation of the infusion. IV vasopressin, at the same concentration, caused no change in HBF throughout the ten minute infusion. These observations indicate that the canine hepatic arterial circulation responds to vasopressin with vasoconstriction characterized by autoregulatory escape. By any of the three routes of administration, vasopressin causes a significant and sustained reduction in blood flow through the superior mesenteric artery. Autoregulatory escape, from vasopressin-induced mesenteric arterial constriction, is not observed. Based on these observations, significant changes in mesenteric arterial blood flow can be anticipated without associated significant changes in hepatic arterial blood flow, regardless of the route of administration of vasopressin.

Animals↗
PubMed1978

Microvascular architecture of anthropoid primate intestine.

Microvascular architecture of the small intestine of New World monkey, ape, and man was examined with the silicone rubber injection technique and the results compared to previous observations in dogs and Old World monkeys. In man, chimpanzee, and New World monkey the small intestine villus contains a single centrally located vein draining a subepithelial capillary plexus converging at the apex of the villus. These villi also contain a single eccentrically located artery rising to the midlevel of the villus, where it branches into subepithelial capillaries over the rest of its length. This vascular architecture most closely resembles that observed in the gut of Old World monkeys in which the villus artery is absent altogether. This observation contrasts the microvascular architecture of canine intestinal villi in which marginal arteries surround a centrally located vein. These patterns of microvascular anatomy are analyzed in terms of the role of the gut in the pathogenesis of experimental shock. The differences observed may account for the known species variations in canine and primate experimental shock.

Adult↗
PubMed1978

Dying in hospital.

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Attitude to Death↗
PubMed1978

Primate mesenteric blood flow. Effects of vasopressin and its route of delivery.

The effects of vasopressin on blood flow in the superior mesenteric artery and on mean arterial pressure and portal venous pressure were measured in 7 rhesus monkeys. Vasopressin was injected, as either a bolus, or infused both intravenously and intraarterially to assess the influence of the route of administration upon hemodynamic responses. Dose-dependent decreases in superior mesenteric arterial flow were observed during both intraarterial and intravenous injections of vasopressin. No statistically significant differences between the two routes of administration, the decrease in flow, and changes in pressure were observed. Based upon these observations, one might anticipate that intravenously administered vasopressin will be as effective as intraarterially administered vasopressin in reducing mesenteric blood flow, and thus portal venous pressure, in man.

Animals↗