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Biomedical subjects

K G Swan

Publications and source records attributed to K G Swan.

At least 73 records · Page 4Linked to original sources
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↗
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↗
PubMed1980

Gunshot wounds of the orbit.

Isolated gunshot wounds of the orbital contents are relatively rare, and therefore their management deserves updating in terms of current practices. Two cases of isolated gunshot wounds to the orbital contents are presented, and the diagnosis, management, and prognosis are reviewed. In general, in the absence of light perception, enucleation within a planned timetable is the treatment of choice to prevent sympathetic ophthalmia from destroying sight in the uninjured eye. If light perception is present, every attempt should be made to preserve the injured eye. Enucleation of a blind injured eye is the treatment of choice because it is a more complete eradication of the potential for sympathetic ophthalmia. In selected cases, evisceration can be successfully substituted.

Adult↗
PubMed1980

Distal splenorenal (Warren) shunt following nephrectomy for renal cell carcinoma: case report.

A 61-year-old man, who had previously undergone a mesocaval shunt for recurrent bleeding from esophageal varices secondary to portal hypertension and cirrhosis of the liver, experienced postoperative hemorrhage, again from esophageal varices. Angiographic evaluation of the thrombosed mesocaval shunt revealed an unanticipated left renal cell carcinoma, which was treated with radical left nephrectomy. The left renal vein was then anastomosed to the splenic vein, end-to-side fashion. The splenic vein was ligated at its junction with the superior mesenteric vein to affect a dital splenorenal (Warren) shunt. Pressure within the patient's splenic vein was reduced from 35 to 25 cm H2O. Grossly, and ultimately histologically, there was no evidence of tumor within the left renal vein. The patient made an uneventful recovery and has experienced no further bleeding from esophageal varices.

Adenocarcinoma↗
PubMed1979

Clinical implications of blood gas analysis of chest tube drainage.

Blood gas analysis of chest tube drainage following thoracostomy for experimental and clinical penetrating chest injuries was evaluated to determine its usefulness in predicting the etiology of the injury. Twenty dogs were divided into four groups and sustained right chest injury as follows: Group I--closed chest lung laceration; Group II--open chest lung laceration; Group IIII-gunshot wounds; Group IV--thoracotomy and injection of autologous, mixed venous blood. All animals and 14 patients who sustained penetrating chest injury were made simultaneously from chest tube draininage, systemic artery, and central vein in all dogs and patients. Eight patients (Group A) had pneumothorax; six patients (Group B) did not. Mean control canine aortic PO2 and pulmonary arterial PO2 values in Group I did not differ significantly from those in the other three canine groups, nor from the two human groups. Group II dogs exhibited chest tube PO2 which was significantly (p less than 0.01) above aortic PO2. In Group IV, chest tube PO2 was increased significantly above pulmonary arterial blood. Patients without pneumothorax had values for PO2 in chest tube drainage and aorta which were not significantly different, whereas when pneumothorax was present, PO2 of chest tube drainage was significantly higher than that of aortic PO2. Thus blood gas determinations on chest tube drainage may reflect the nature of the injury; however, the presence of air in the pleural space can result in oxygenation of contained blood well above systemic arterial levels.

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

A prospective randomized study of three expanded polytetrafluoroethylene (PTFE) grafts as small arterial substitutes.

A prospective, double-blind, randomized study was performed to determine the relative patency rate of polytetrafluoroethylene (PTFE) grafts, Gore-Tex, Impra, and a Surgikos prototype PTFE graft. The 48 grafts (40 x 4 mm) replaced excised segments of femoral arteries in adult mongrel dogs, whose mean weight was 20.6 +/- 0.9 kg; the grafts were removed after 12 weeks. Sterile technique and antibiotic therapy were included in the study. Anticoagulation was not employed. Anastomoses were performed with 6 = 0 polypropylene. Angiographic assessment of each anastomosis was made at surgery and prior to sacrifice. Patency was assessed daily by palpation and Doppler flow signals, as well as angiographically, prior to sacrifice. The overall patency rate was 62.5%. There were no statistically significant differences in patency rates among the three groups (Gore-Tex, 56%; Impra, 75%, Surgikos, 56%). Histologic evaluation revealed incomplete neointima formation and significant pannus formation in all three types of grafts without any significant discernible difference among them. The results suggest that further experimental evaluation of PTFE, as a small vessel substitute, is indicated prior to its use clinically in preference to autogenous vein.

Animals↗