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Biomedical subjects

W G Schenk

Publications and source records attributed to W G Schenk.

At least 19 recordsLinked to original sources
PubMed1992

Aspergillus flavus wound infection following repair of a ruptured duodenum in a non-immunocompromised host.

Aspergillus flavus is generally considered to be an opportunistic organism, rarely causing clinical infections in the immunocompetent host. We present a case of a 79-year-old man without history of immunocompromise who developed a severe aspergillus wound infection in an open wound following repair of a traumatic duodenal perforation. Despite aggressive treatment, this invasive infection contributed significantly to his eventual demise.

Aged↗
PubMed1990

Experimental inhalation injury with concomitant surface burn: dextran resuscitation improves lung water and oxygenation.

UNLABELLED: The role of extravascular lung water (EVLW) in the pathogenesis of inhalation injury (INH) when associated with concomitant major burn (B) remains controversial. Previous experimental models have investigated isolated INH without surface burn. This study measured the effects of isolated and combined INH on EVLW and pO2 in a porcine experimental model. The beneficial effects of early resuscitation with dextran-40 (DEX) were assessed, using a control group receiving standard Parkland formula (LR). In the first part of the study (INH vs. INH + B), a group of animals with a standardized INH was compared to a group also receiving a standardized 40% BSA third-degree surface burn (n = 8, each group). With serial measurements for 5 hours, EVLW was only modestly increased unless INH was accompanied by surface burn: 20.3 +/- 4.2 vs. 32.0 +/- 4.1 ml/kg at 5 hours (p less than 0.01). Similarly, pO2 fell much more dramatically in the INH + B group, 61 +/- 5 vs. 37 +/- 5 torr (p less than 0.05). The second part of the study compared standard Parkland crystalloid resuscitation with dextran-40 resuscitation in animals receiving a combined INH + B injury (LR vs. DEX, n = 8, each group). DEX resuscitation resulted in substantially lower accumulation of EVLW out to 5 hours, 34.1 +/- 5.0 vs. 13.1 +/- 3.0 ml/kg (p less than 0.01), and significantly better pO2, 35 +/- 5 vs. 64 +/- 4 torr (p less than 0.01). CONCLUSIONS: Inhalation injury did not dramatically increase EVLW in this animal model unless accompanied by concomitant major surface burn. The deterioration in EVLW and pO2 seen in the combined injury was significantly improved with DEX resuscitation when compared to standard crystalloid resuscitation. Further study is indicated and clinical trials may be warranted.

Animals↗
PubMed1989

Differentiating pancreatic pseudocyst and pancreatic necrosis using computerized tomography.

Ten per cent of patients with acute pancreatitis will develop pancreatic complications. Differentiating pancreatic pseudocyst formation from pancreatic necrosis may be difficult based on clinical grounds. The purpose of this study was to evaluate the role of computerized tomography in differentiating these processes. A retrospective analysis was performed of 40 patients who developed pancreatic complications following an episode of acute pancreatitis and who subsequently underwent operation for drainage of their pancreatic fluid collections. All 40 patients had abdominal CT scans performed before surgery and the patients were then categorized on the basis of CT findings as having (1) a pseudocyst with a well-defined cyst wall, (2) peripancreatic fluid marked by the absence of a cyst wall, and (3) a combination of a pseudocyst as well as free peripancreatic fluid. Patients with pseudocysts had an average hospital stay of 14 +/- 2 days, a hospital morbidity rate of 16%, and a hospital mortality rate of 0%. In contrast, patients with peripancreatic fluid collections had an average hospital stay of 43 +/- 4 days (p less than 0.01) and hospital morbidity and mortality rates of 74% (p less than 0.01) and 22% (p less than 0.05), respectively. Patients with both pseudocysts and peripancreatic fluid collections behaved in a similar fashion to patients with peripancreatic fluid alone as characterized by a prolonged hospital stay and a high incidence (80%) of postoperative complications. At one year follow-up, 89% of the patients with pseudocysts were asymptomatic, whereas only 13% (p less than 0.01) of patients with peripancreatic fluid were symptom free. These data demonstrate that pseudocyst and peripancreatic fluid collections have markedly different biologic characteristics both in their short-term and long-term behavior. The results suggest that CT scanning can differentiate these processes and may help in directing the appropriate surgical therapy.

Acute Disease↗
PubMed1986

Evaluation of insulin secretion after pancreas autotransplantation by oral or intravenous glucose challenge.

Segmental pancreatic autotransplantation is accompanied by surgical alterations to the pancreas that may have consequences for carbohydrate metabolism. Four mongrel dogs were evaluated before operation and sequentially until 40 weeks after total pancreatectomy and autotransplantation of the splenic lobe of the pancreas with bolus intravenous and oral administration. Intravenous glucose tolerance test (IVGTT) (0.5 g/kg) revealed maintenance of fasting euglycemia for as long as 40 weeks after operation. Peak glucose and integrated glucose values did not show significant changes as a result of autotransplantation. Following transplantation, a delayed peak insulin response was seen; however, basal, peak, and integrated insulin values were largely unaltered. Only K values, a measure of glucose disposal, showed severe alterations (2.44 +/- 0.21 before operation to 1.24 +/- 0.30 at 40 weeks after operation). Oral glucose tolerance tests (OGTT) (2.0 g/kg) demonstrated an increased peak hyperglycemic response after autotransplantation with increased integrated glucose responses. Insulin levels remained at those levels seen before operation, and glucose-dependent insulinotropic polypeptide (GIP) responses were unchanged during the OGTT as late as 20 weeks after operation. In conclusion, pancreas autotransplantation after total pancreatectomy results in significant metabolic alterations that the IVGTT fails to detect with absolute glucose or insulin levels. However, K values are significantly lowered, which indicates alterations in cellular glucose transport. The OGTT demonstrates hyperglycemia without increased insulin or GIP levels, which suggests an altered beta cell response to the enteric stimulus of insulin release. These changes are nonetheless well tolerated by animals that have remained clinically healthy and euglycemic in the basal state.

Animals↗
PubMed1986

Indications for emergency intravenous pyelography (IVP) in blunt abdominal trauma: a reappraisal.

Renal imaging in the diagnostic evaluation of blunt abdominal trauma is a valuable adjunct, but its indications remain controversial. Classic indications for the use of emergency intravenous pyelography (IVP) have been liberal, but more recently the medical need, cost effectiveness, and potential risks of this approach have been questioned in favor of a more selective approach. This retrospective study was undertaken to reassess the value of emergency IVP in blunt abdominal trauma and to test the hypothesis that post-traumatic microscopic hematuria, without other physical or laboratory findings, can safely be managed by observation alone. With the aid of the computerized Trauma Registry at the University of Virginia Medical Center, 50 consecutive patients undergoing emergency IVP for blunt abdominal trauma were identified over a 1-year period. A significantly abnormal IVP was found in six of seven patients with gross hematuria (86%). No patient of 43 with microscopic hematuria had a clinically significant abnormality (p less than 0.001, Chi-square). Three patients in the latter group (7%) had IVP findings which were anatomically abnormal but clinically insignificant, while an equal number (7%) had IVP's which were inadequate or misleading. Emergency IVP is useful in patients with specific indications and gross hematuria, but patients with post-traumatic microscopic hematuria alone may be safely followed by observation. Abdominal CT scanning is emerging as a more useful study than IVP for renal imaging in the stable patient with blunt abdominal trauma.

Abdominal Injuries↗
PubMed1979

Experimental acute pancreatitis: the changes in pancreatic oxygen consumption and the effect of Dextran 40.

A canine model was devised to measure the oxygen consumption of the pancreas in experimentally induced pancreatitis. Over the 120 minute investigation period the oxygen consumption fell by 63% in the presence of a diminishing pancreatic blood flow and constant arteriovenous percentage saturation across the pancreas. Dextran 40 has been previously shown to maintain the pancreatic circulation. Accordingly a second group of dogs was treated with Dextran 40 (1.5 ml/kg) 60 minutes after induction of the pancreatitis. This produced a significant increase in the pancreatic oxygen consumption and widening of the arteriovenous difference. Dextran 40 appears to reverse the hypoxia of the pancreas noted in acute experimental pancreatitis.

Acute Disease↗
PubMed1979

Hypercalciuresis in trauma patients on high-nitrogen enteral and parenteral diets.

Calcium balances in ten enterally or parenterally hyperalimented trauma victims were compared as protein intake was manipulated from 50.5 +/- 12.8 to 128.0 +/- 17.4 gm/day during an isocaloric metabolic balance study. Calciuresis increased as protein intake increased in all subjects, resulting in an average reduction in daily calcium balance of 195 +/- 65 mg/day (p less than 0.001). There was no difference in fecal calcium in the enterally fed subgroup. Total and "corrected" total serum calcium were lowered, and indirect evidence suggests that ionized calcium was lowered as well. The mechanism of the increase in urinary calcium is not fully elucidated, although it appears to be a direct effect on the kidney rather than an indirect influence of calcium homeostasis. It is suggested that a calorie/nitrogen ratio of about 360 be maintained in enteral and parenteral alimentation of trauma victims. Thus nitrogen balance can be maintained by the increased nonprotein calorie availability, and possible complications of increased calcium mobilization and excretion can be avoided.

Adolescent↗
PubMed1978

Hepatic blood flow measurement.

Although many experimental studies have been made to determine the total hepatic blood flow in steady circulatory states, very few have been done in unsteady states of either circulatory overload or underload. In this experiment, a comparison is made between total hepatic blood flow measured by the single injection of indocyanine green and the electromagnetic flow methods in the dog, in which circulatory overload was induced by dextran 40 infusion. While there was close correlation between the values obtained by the two methods in normal dogs, following dextran infusion the indirect indocyanine green method overestimated hepatic blood flow by 40% to 60%, using the electromagnetic method as a comparison standard. The reason for this discrepancy is not elucidated by these studies.

Animals↗
PubMed1978

Hepatic blood flow measurement III. Total hepatic blood flow measured by ICG clearance and electromagnetic flowmeters in a canine septic shock model.

The validity of the ICG clearance method for the measurement of THBF in abnormal circulatory states remains questionable. In this study THBF measured by this method is compared with the electromagnetic flow technique in a canine spetic model. Good correlation is demonstrated between the two in normal control animals. However, in the septic animals the ICG underestimated the electromagnetic flow result by 20%. This is true in both the high and the low cardiac output septic shock pictures that emerge. In the septic animals, the total hepatic blood flow as measured by the ICG was almost equal to the portal vein flow alone measured by the electromagnetic flowmeters suggesting that this was the quantity it was measuring in this abnormal state. Pathophysiologic mechanisms that may explain the discrepancy are given.

Animals↗
PubMed1978

Experimental pancreatitis: Effect of plasma and dextran on pancreatic blood flow.

In spite of extensive investigations, many aspects of the hemodynamic changes occurring in acute pancreatitis are understood poorly. A dog model was established in which continuous measurements of pancreatic arterial blood flow, cardiac output, and mean arterial blood pressure were made using electromagnetic flow probes and a pressure transducer, respectively. Pancreatitis was induced and the animals were monitored for 3 hours. In addition, control animals (group I) without pancreatitis also were done. All animals 50 ml of saline in the first hours. Three methods of therapy then were instituted in the dogs with pancreatitis and their effects were recorded. group I 6 dogs control animals no pancreatitis saline 50 ml/hr group II 10 dogs saline 50 ml/hr group III 6 dogs plasma 15 ml/kg over 45 min then saline 50 ml/hr group IV 10 dogs saline 50 ml and 1.5 ml/kg of dextran 40/hr These results confirm the observations made previously using a transillumination technique--that the pancreatic circulation rapidly reduces in acute pancreatitis. Administration of plasma produced a significant (P less than 0.05) but transient increase in the cardiac output and pancreatic blood flow; however, the blood pressure remained low. Dextran 40 minimally increased cardiac output, but it significantly improved the blood pressure and maintained the pancreatic blood flow. Low-dose, low-molecular weight dextran 40 appears to help to maintain pancreatic blood flow in acute pancreatitis. The possible mechanisms concerning the made of action of dextran 40 will be discussed.

Animals↗
PubMed1977

Hepatic blood flow measurement. A comparison of the indocyanine green and electromagnetic techniques normal and abnormal flow states in the dog.

Very few studies have compared the total hepatic blood flow using the Indocyanine green (ICG) method with the instantaneous electromagnetic flow method under unsteady circulatory conditions. In this study, a hypotensive circulatory state was produced by rapid hemorrhage in 14 dogs. Total hepatic blood flow was measured using the ICG single injection method, comparing it with the electromagnetic flow method. After confirming the validity of the ICG single injection method in measuring total hepatic blood flow in the steady state, the experiment was then carried out using 23 normal healthy dogs. The close correlation between the ICG clearance technique and the electromagnetic values under normal steady state was confirmed. However, after hemorrhage the indirect ICG method estimated only 71% of the simultaneous electromagnetic flow value. It is reasonable to assume that while the electromagnetic method continues to measure the actual total hepatic blood flow in both the steady and unsteady states, the ICG clearance method measures only the functional hepatic blood flow which is reduced due to shunting or impaired hepatocellular function in the unsteady and hypotensive circulatory state.

Animals↗
PubMed1977

Hypertension of aortic coarctation: the role of renal and other factors.

In order to establish the relationship between the renal and other factors associated with the hypertension of coarctation of the aorta, aortic strictures were created in two groups of adult dogs (Groups A and B). Group B in addition had transference of total renal blood flow proximal to the stricture to eliminate the renal aspects of the hypertension. Carotid and femoral artery pressures were measured at monthly intervals for 24 weeks. Group A developed progressive generalised hypertension while Group B only developed hypertension proximal to the coarctation. The dominant role of a renal factor producing a generalised vascular response is confirmed, the localised proximal hypertension in Group B reflecting the mechanical obstruction imposed by the aortic stricture. There is no evidence to suggest that other organs distal to the coarctation are implicated in the development of arterial hypertension.

Animals↗
PubMed1977

Recent advances in the management of trauma.

Delivery of the most up-to-date trauma care requires a well-trained team of four physicians and four nurses to carry out the initial management of a single major injury patient (Border et al, 1975). Ventilatory insufficiency, circulatory insufficiency, and wounds must all be treated promptly and simultaneously.

Cardiovascular Diseases↗