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Biomedical subjects

T Schroeder

Publications and source records attributed to T Schroeder.

At least 91 records · Page 5Linked to original sources
PubMed1991

[Mortality and survival after surgery for abdominal aortic aneurysm. A 10-year follow-up].

From 1979-1988, 656 patients were operated for abdominal aortic aneurysm. The perioperative mortality was 18%. The mortalities for elective, symptomatic and ruptured aneurysms were 5%, 17% and 38% respectively. The overall five year survival rate was 58%. In 87% of the patients one or more risk factor was found. Survival was unaffected in patients with a single risk factor, whereas patients with two or more risk factors had lower five year survival. Postoperative organ failure increased the perioperative mortality and the five year survival in patients with multiorgan failure was 20%. In view of the fact that 56% of the patients are operated on as emergencies, this study stresses the importance of early diagnosis and elective treatment.

Adult↗
PubMed1991

The effect of arteriovenous fistulas on in situ saphenous vein bypasses.

Intraoperative identification and later development of arteriovenous fistulas were investigated prospectively in 70 in situ saphenous vein bypass procedures. Surveillance was performed by completion arteriography and intra- and postoperative continuous wave Doppler examination. The intraoperative Doppler examination identified 89% of those branches with sufficient flow to opacify the deep venous system on completion arteriogram. Half of the missed fistulas underwent spontaneous thrombosis, and in only one case did the arteriovenous fistula lead to hemodynamic symptoms demanding surgical closure of the fistula. Pursuing a policy of selectively ligating fistulas that only fill the deep venous system on completion arteriography led to an additional nine arteriovenous fistulas. Developed over an average follow-up of six months, four patients presented symptoms of edema and swelling and were relieved upon closure of the fistulas. The incidence of bypass thrombosis did not differ significantly among patients with remaining arteriovenous fistulas, patients who developed fistulas during follow-up, and patients who had no signs of arteriovenous fistulas. It seems justified to continue selective intraoperative ligation of arteriovenous fistulas based on continuous wave Doppler.

Adult↗
PubMed1991

Effect of labetalol on cerebral blood flow and middle cerebral arterial flow velocity in healthy volunteers.

The effect of labetalol, a combined alpha- and beta-adrenoceptor antagonist, on the cerebral circulation was investigated in 7 normotensive subjects. Cerebral blood flow (CBF) was measured with the intravenous 133Xe method and mean flow velocity (Vmean) in the middle cerebral artery was determined using transcranial Doppler (TCD) ultrasound. Examination was performed before and then 15, 60 and 120 min after 0.75 mg/kg i.v. labetalol. Reactivity to inhalation of 5% CO2 in air was studied before, and again 90 min after labetalol administration. Neither CBF nor Vmean changed following labetalol administration, whereas a marked increase occurred during inhalation of CO2. The median CO2 reactivity was 3.2%/mmHg (range: 1.8-4.0) for CBF and 4.4%/mmHg (1.5-5.6) for Vmean. These results indicate that labetalol, given in moderate but clinically relevant doses, does not affect the cerebral circulation in normotensive subjects. Neither does it affect CO2 reactivity. The uniform results obtained with the two methods suggest TCD as a usable alternative to conventional CBF technique in the assessment of cerebral vasoactivity of various drugs in subjects with a normal cerebral circulation.

Adult↗
PubMed1991

Recent contributions to transplantation at the University of Cincinnati.

1. Clinical investigations at the University of Cincinnati have focused primarily on infection control, methods to increase donor-specific unresponsiveness, improvement in immunosuppression, donor maintenance and evaluation, posttransplant monitoring, and reduced-size livers for children. 2. Donor specific unresponsiveness (DSU) can be achieved frequently in recipients of both cadaver donor and living related donor kidneys by giving a single donor specific transfusion and CsA only 24 hours preoperatively with continuing triple immunosuppressive therapy. 3. Prednisone can be withdrawn from almost all patients with no rejection by 1 year with significant improvement in blood pressure, daily insulin requirement in diabetics, total blood cholesterol, and low density lipoproteins (LDL). 4. Oral ketoconazole 200 mg/day can be used safely to block the hepatic metabolism of CsA and reduce the amount of CsA administered by an average of 77-88%. This is of great economic consequence to lower income patients and patients with poor drug absorption. 5. Eighteen patients with SLE who received 23 kidney transplantations had an increase in graft loss in the first 6 months but the rate of graft loss after 6 months was almost identical to other ESRD patients. 6. The Cincinnati Transplant Tumor Registry has data on about 8,000 patients. Except for those with CNS tumors, patients with active cancers should not be used as donors. However, donors with previous curative procedures should not be excluded automatically. Cancers arising in immunosuppressed transplant recipients that have a higher incidence than the general population (expressed as percentage of treated cancers) are: lymphomas (22% vs 5%), lip cancers (7% vs 0.3%), Kaposi's sarcoma (6% vs less than 0.1%), vulva and perineal cancers (4% vs 0.6%), hepatobiliary cancers (2.5% vs 1.0%) and sarcomas (1.8% vs 0.5%). Other cancers have about the same-distribution. 7. Immunologic monitoring during OKT3 therapy is particularly useful in re-treatment and treatment of pediatric liver patients when increased doses of the drug may be necessary. 8. The MEGX test has been found to be a major predictor of primary non-function of the transplanted liver, and it is also useful in predicting the risks of dying from liver disease. 9. Reduced-size livers have been used in 37 patients, representing almost half of all pediatric liver transplants. Survival with reduced-size grafts (91% at 1 year) compared favorably with survival of whole organs (79% at 1 year). The benefit is particularly dramatic in infants with biliary atresia (100% 1-year graft survival in 24 patients, median age 11 months).(ABSTRACT TRUNCATED AT 400 WORDS)

Actuarial Analysis↗
PubMed1990

[Hemodynamic assessment of cerebrovascular circulation using transcranial Doppler ultrasound in patients with carotid stenosis].

Transcranial Doppler-ultrasound (TCD) is a new non-invasive technique which renders continuous monitoring of the rate of flow in the major intracerebral arteries possible. The method appears, therefore, to be attractive for perioperative monitoring of patients submitted to operation on account of carotid stenosis. Seventeen patients were included in this preliminary investigation. These patients were submitted for thromboarterectomy of the internal carotid artery. Preoperatively the average flow rate (Vmean) in the ipsilateral medial cerebral artery measured at rest was 54 cm/second (range 34-94) as compared with 57 cm/second (range 32-86) in the contralateral medial cerebral artery. During occlusion, Vmean in the ipsilateral medial cerebral artery decreased momentarily, on an average 35% (p less than 0.001), and returned to the preoperative level after reopening of the internal carotid artery. Corresponding but no significant changes were observed in the pulsatile index. The preliminary experience suggests that TCD is scarcely useful as a diagnostic method in individual cases but that it is well suited for continuous monitoring of changes in cerebral circulating during surgery on the internal cerebral artery. Further assessment of the technique is necessary before the method can be employed routinely, mainly on account of the great interindividual scatter.

Aged↗
PubMed1990

[Femoro-popliteal bypass surgery in Denmark 1983-1987].

In a retrospective study of femoro-popliteal bypass surgery in Denmark during the period 1983 to 1987, a total of 1,532 operations were performed. Approximately 2/3 of the patients were operated upon for limb salvage, the remainder for severe disabling claudication. The perioperative lethality was below two per cent in all departments. Early occlusion rate was found to be between 21 and 11 per cent, leading to major amputation in about half of the patients.

Arteriosclerosis↗
PubMed1990

[Femoro-crural reconstruction in Denmark 1983-1987].

From 1983 to 1987, 293 femoro-crural bypasses were performed in eight centers for vascular surgery in Denmark. The activity increased in the period from 15 to 135 bypasses per year. The increase took place particularly 1986, when the in situ saphenous vein bypass was introduced in Denmark. A total of 203 bypasses were performed at the University Hospital of Copenhagen, Rigshospitalet: 108 in situ bypasses, 51 bypasses with arterial protheses and 44 bypasses using reversed vein. The cumulated graft patency after one year was 76% for the in situ bypasses, 26% for the bypasses with arterial protheses and 32% for reversed vein. The cumulated limb survivals after one year were 90%, 66% and 63%, respectively.

Adult↗
PubMed1990

[Early and late results after surgery of abdominal aortic aneurysm].

From 1983-1987, 388 patients were operated upon for abdominal aortic aneurysm. Elective operation was performed on 171 patients (44%) with a mortality of 2.9%. Emergency operation was done in 277 patients of whom 132 (34%) had ruptured aneurysms. The mortality for ruptured aneurysms was 36% and 21% for patients operated on as emergencies without signs of rupture of the aneurysm. The five year survival rate was 75% after elective operation, 60% after emergency operation and 40% after operation for ruptured aneurysm. The high mortality after emergency operation for abdominal aortic aneurysm confirms the importance of early diagnosis and elective operation before rupture occurs.

Aorta, Abdominal↗
PubMed1990

[Neurologic complications in connection with the surgical treatment of 577 cases of carotid artery stenosis].

During the period January 1982 till June 1988, 536 patients underwent 577 carotid thrombendartectomies in the Department of Vascular Surgery RK in the University Hospital in Copenhagen. Preoperatively, 270 patients (47%) had experienced transient ischaemic attacks (TIA), 247 (43%) had experienced stroke (APC) and 19 (3%) had non-focal symptoms while 41 (7%) had asymptomatic stenoses. Postoperatively, 17 (2.9%) patients developed TIA, 22 (3.8%) developed slight neurological symptoms and 40 (7%) had more severe neurological complications and six of these (1%) died. None of the patients died from other causes during the first month. The frequency of complications had no relationship to the preoperative focal symptoms, but in patients with non-focal symptoms this was 37%. The degree of stenosis of the contralateral internal carotid artery (ICA) was correlated positively with the occurrence of severe neurological complications which were observed in 5% without contralateral ICA changes, in 7% with stenoses and in 20% with contralateral ICA occlusion. Patients with cerebral infarction developed complications significantly more frequently (20%) than patients with normal CT scans. The risk was also found to be increased in cases with a high pressure gradient across the stenosis and low pressure peripherally in the occluded artery (stump pressure). Follow-up examination of the 73 patients with complications on average 39 months after operation revealed that 37 patients (6.4%) had severe neurological symptoms resulting either from the operation or subsequent APC; seven patients required complete nursing care (1.2%) and 17 patients died during the period of observation. On follow-up examination, 15 patients had been occupationally active for at least 1.5 years.

Adult↗
PubMed1990

Pressure/cross-sectional area probe in the assessment of urethral closure function. Reproducibility of measurement.

A probe, which enables measurement of related values of pressure and cross-sectional area, was used for in vitro studies and in vivo measurements in the female urethra. Six healthy females underwent two successive investigations. Measurements were performed at the bladder neck, in the high-pressure zone and distally in the urethra. The in vitro study showed that cross sectional areas of 13-79 mm2 were determined with a SD of 1.4 mm2. In vivo measurements revealed that the urethral parameters: elastance, hysteresis, pressure and power of contraction during coughing and squeezing were fairly reproducible. However, a certain interindividual variation of the parameters was found.

Adult↗
PubMed1990

Renal failure after operation for abdominal aortic aneurysm.

Among 656 patients undergoing surgery for abdominal aortic aneurysm, 81 patients (12%) developed postoperative renal failure. Before operation hypotension and shock occurred in 88% of the patients with ruptured aneurysm, whereas none of the patients operated electively were hypotensive. Dialysis was performed in 32 patients, while the remaining 49 patients were managed without dialysis. Within 30 days after the operation 47 patients (58%) had died. There was no difference in mortality between patients in dialysis and patients managed without dialysis. Thirteen patients died during follow-up. In six cases the death was caused by renal failure only or in combination with failure of other organs. Analysis of the cumulative survival shows that, if the patients survive the postoperative period, their life expectancy is comparable to that of patients without renal complications.

Acute Kidney Injury↗
PubMed1990

Eight to ten years follow-up after carotid endarterectomy: clinical evaluation and Doppler examination of patients operated on between 1978-1980.

Follow-up information was obtained on 185 patients who consecutively underwent carotid endarterectomy eight to ten years previously. Doppler ultrasound examination was performed in 59 patients who were still alive and living within 100 miles of the hospital. Using lifetable analysis, the annual rate of focal strokes was estimated to be 2% and 1.5% on the operated and the contralateral, non-operated carotid artery, respectively. Doppler examination revealed 48% re-stenoses, including 14% occlusion and 15% greater than 50% stenosis. However, there was no association between the occurrence of restenosis and the development of symptoms, perhaps with the exception of internal carotid artery occlusion, which is not an accepted indication for carotid endarterectomy. Together with recent data from the literature, these observations challenge the indication for reoperative carotid surgery.

Carotid Arteries↗
PubMed1990

Carotid artery disease and low cerebral perfusion pressure: symptomatology, operative risk and outcome.

Direct internal carotid artery blood pressure measurements in patients undergoing carotid endarterectomy identified 49 patients, among 239 consecutive cases (21%), who had a reduction in perfusion pressure of 20% or more. The clinical history, objective findings and angiographic data were compared with those of a control group of a further 49 patients selected from the remaining patients operated on over the same period. The two groups were compared for short- and long-term outcome of surgery. We were unable to delineate a symptomatic neurological profile that identified patients with low perfusion pressures. Surgery in patients with low perfusion pressures seemed to be associated with an increased complication rate (12% versus 4%), although this was not statistically significant. Definite postoperative improvements in persisting neurological deficits were observed only in one patient. Long-term results were equal in the two groups with an annual stroke risk of 3%.

Adult↗
PubMed1990

Intraoperative 133Xe cerebral blood flow measurements by intravenous versus intracarotid methods.

To document the comparability of cerebral blood flow (CBF) values determined by quantification of 133Xe washout after either intravenous or intracarotid administration, 12 patients undergoing elective carotid endarterectomy anesthetized with N2O/O2 and either isoflurane or halothane were studied. Scintillation counters were placed over the middle cerebral artery territory ipsilateral to the operated carotid artery. CBF was measured by the intravenous method during dissection of the carotid sheath and was calculated as the initial slope index from head washout curves collected for 11 min after injection of 10-20 mCi 133Xe in saline into a large vein. Immediately prior to carotid occlusion, CBF was determined by direct injection of 1 mCi 133Xe in saline into either the internal carotid artery or the common carotid artery with the external carotid artery occluded. For the intracarotid injections, the initial slope was calculated from the 1st min of washout. Data were analyzed by linear regression and analysis of variance. Values are expressed as mean +/- SD. The mean CBF for intravenous and intracarotid methods were both 29 +/- 10 ml.100 g-1.min-1. The correlation between CBF measured by intravenous and intracarotid methods was excellent and was described by the line y = x + 0.6, r = 0.92. We conclude that in the flow range studied, the intravenous technique may be applied to measure CBF in physiologically stable situations in which direct intracarotid injection is not feasible.

Anesthesia, Inhalation↗
PubMed1990

Cerebral blood flow during static exercise in humans.

Cerebral blood flow (CBF) was determined in humans at rest and during four consecutive unilateral static contractions of the knee extensors. Each contraction was maintained for 3 min 15 s with the subjects in a semisupine position. The contractions corresponded to 8, 16, 24, and 32% of the maximal voluntary contraction (MVC) and utilized alternate legs. CBF (measured by the 133Xe clearance technique) was expressed by a noncompartmental flow index (ISI). Heart rate and mean arterial pressure increased from resting values of 73 (55-80) beats/min and 88 (74-104) mmHg to 106 (86-138) beats/min and 124 (102-146) mmHg, respectively (P less than 0.0005), during the contraction at 32% MVC. Arterial PCO2 and central venous pressure did not change. Corrected to the average resting PCO2, CBF during control was 55 (35-73) ml.100 g-1.min-1 and remained constant during contractions. Cerebral vascular resistance increased from 1.5 (1.0-2.2) to 2.4 (1.4-3.0) mmHg. 100 g.min.ml-1 (P less than 0.025) at 32% of MVC. There was no difference in CBF between the two hemispheres at rest or during exercise. In contrast to dynamic leg exercise, static leg exercise is not associated with an increase in global CBF when measured by the 133Xe clearance technique.

Adult↗
PubMed1990

Improvement of peroral absorption of cyclosporine A by microemulsions.

The rat was found to be a suitable model for pharmacokinetic and bioavailability studies of cyclosporine A (CsA). All pharmacokinetic parameters studied were in the same order of magnitude as those found in man. Two peroral formulations in the form of microemulsions were compared with a commercially available P.O. solution (to be diluted for administration) and a solution for intravenous administration. Of the two microemulsions, one resulted in an extent of absolute and relative bioavailability significantly higher than that of the available P.O. solution. Biliary recycling was observed upon all routes of administration. If uncorrected for biliary recycling, both absolute and relative bioavailability are overestimated.

Administration, Oral↗
PubMed1989

[Referrals for carotid surgery during the period 1977-1986. The referral pattern for patients with carotid stenosis in the catchment region of the University Hospital in Copenhagen, assessed during a 10-year period].

Although carotid endarterectomy has been carried out for over 30 years, there are as yet no investigations which prove the value of this form of treatment with certainty. Attitudes to carotid surgery also vary greatly. The authors have assessed this variation during the period 1977-1986 on the basis of the lists of patients admitted to the Department of Vascular Surgery in the University Hospital. Patients from Funen and Jutland were excluded from the material because endarterectomy is also carried out in hospitals in these regions. A total of 720 patients from two extensive municipalities and six counties were admitted. During the period involved, increase in the number of referrals and also in the number of operations carried out occurred until 1984. After this, and in accordance with the global more restrictive attitudes, fewer patients were referred. Great regional variations were found as 8-10 as many patients per 100,000 inhabitants between 50 and 70 years were referred from the Municipality of Copenhagen as from the county which referred fewest patients. It is concluded that there are considerable differences in the treatment of patients with carotid stenosis within the catchment region of the University Hospital in Copenhagen.

Aged↗