Biomedical subjects

Burkhardt Seifert

Publications and source records attributed to Burkhardt Seifert.

64 records · Page 4Linked to original sources

PubMed2002

Preoperative clonidine blunts hyperadrenergic and hyperdynamic responses to prolonged tourniquet pressure during general anesthesia.

UNLABELLED: Although the mechanism of tourniquet-induced hypertension is still unclear, plasma norepinephrine concentrations continuously increase in parallel to arterial blood pressure during tourniquet inflation. Clonidine attenuates hyperadrenergic and hyperdynamic responses. We investigated the effects of clonidine on prolonged tourniquet inflation. Twenty-nine patients scheduled for elective orthopedic surgery were randomly assigned to receive IV clonidine (3 microg/kg; n = 14) or placebo (n = 15) before tourniquet inflation of the lower limbs under general anesthesia in a double-blinded manner. Arterial blood pressure, heart rate, epinephrine, and norepinephrine plasma concentrations were measured before tourniquet inflation, 60 min after tourniquet inflation, just before tourniquet deflation, and 20 min after tourniquet deflation. Mean arterial blood pressure and norepinephrine plasma-concentrations were significantly lower in the Clonidine group compared with Control after 60 min tourniquet inflation (P = 0.016; P = 0.006). Immediately before deflation of the tourniquet, the difference for mean arterial pressure between groups was even more pronounced (P = 0.005). Twenty minutes after deflation mean arterial blood pressure in the Control group was still increased and significantly higher compared with the Clonidine group (P = 0.002). In conclusion, preoperative IV clonidine blunts hyperadrenergic and hyperdynamic responses resulting from prolonged tourniquet inflation under general anesthesia in ASA class I--II patients. IMPLICATIONS: Tourniquet inflation is associated with a continuous increase in arterial blood pressure and sympathetic outflow. This study shows that IV clonidine effectively blunts increases of both arterial blood pressure and plasma norepinephrine concentrations.

Adult↗

PubMed2002

Clinical outcome of edema-like bone marrow abnormalities of the foot.

PURPOSE: To evaluate the clinical outcome of edema-like bone marrow abnormalities seen on magnetic resonance (MR) images of the foot when their cause is unknown. MATERIALS AND METHODS: The clinical outcome of 31 patients (15 female patients, 16 male patients; mean age, 51; range, 10-79 years) with edema-like bone marrow abnormalities on MR images of the foot was determined. The relevance of three different edema patterns was compared: (a) exclusively ill-defined edema-like zones, (b) edema-like zones plus well-defined necrosis-like zones, and (c) edema-like zones plus linear structures indicating possible fractures. The different edema patterns were compared with persistence of pain. RESULTS: Fifty-four percent of all patients had pain persisting after 1 year, as calculated with the Kaplan-Meier method. The duration of pain in the various subgroups varied significantly (P =.049, log-rank test). The subgroup of patients with a well-defined necrosis-like zone had substantially longer-lasting pain than those with edema-like abnormalities only (n = 16) (P =.065). Only one of seven patients with a well-defined necrosis-like zone (n = 7) was pain free after 1 year. Conversely, patients with possible stress fracture (n = 8) had shorter pain compared with those with edema-like abnormalities only (P =.036); six of eight patients were pain free after 1 year. CONCLUSION: Edema-like bone marrow abnormalities of the foot predict long-lasting pain. Analysis of the image patterns of such abnormalities allows prediction of the clinical outcome to a certain degree.

Adolescent↗

PubMed2002

Electrocardiographically gated multi-detector row CT for assessment of valvular morphology and calcification in aortic stenosis.

PURPOSE: To evaluate the applicability and image quality of nonenhanced and contrast material-enhanced multi-detector row computed tomography (CT) combined with retrospective electrocardiographic (ECG) gating for visualization of the aortic valve, determination of aortic valve morphology and diameter of the aortic valve annulus, and assessment of the degree of valvular calcification in patients with aortic valve stenosis, as compared with results of surgery and echocardiography. MATERIALS AND METHODS: Prior to surgical valve replacement, 25 patients with aortic valve stenosis and sinus rhythm underwent nonenhanced (n = 15) and contrast-enhanced (n = 25) retrospectively ECG-gated multi-detector row CT. Two readers working in consensus evaluated image quality and assessed valvular morphology and the degree of valvular calcification. In addition, the diameter of the aortic valve annulus was measured. Results were compared with surgical and echocardiographic findings by using the paired sign test, kappa statistics, and the method of Bland and Altman. RESULTS: The aortic valve could be visualized nearly free of motion artifacts on all multi-detector row CT images. Image quality and diagnostic confidence for classification of aortic valve morphology were significantly superior on contrast-enhanced rather than nonenhanced images (P =.004 and P =.006, respectively). Nonenhanced and contrast-enhanced CT showed good agreement with surgical findings with regard to quantification of the degree of aortic valve calcification (kappa = 0.77 and kappa = 0.74, respectively). Measurement of the diameter of the aortic valve annulus was more reliable on contrast-enhanced images. CONCLUSION: Contrast-enhanced retrospectively ECG-gated multi-detector row CT allows determination of aortic valve morphology, measurement of the diameter of the aortic valve annulus, and assessment of the degree of aortic valve calcification in patients with aortic stenosis.

Aged↗

PubMed2002

Preoperative breast cancer staging: MR imaging of the axilla with ultrasmall superparamagnetic iron oxide enhancement.

PURPOSE: To evaluate magnetic resonance (MR) imaging with ultrasmall superparamagnetic iron oxide (USPIO) enhancement for preoperative axillary lymph node staging in patients with breast cancer by using histopathologic findings as the standard of reference. MATERIALS AND METHODS: MR imaging was performed with a 1.5-T system within 24-36 hours after the start of intravenous slow-drip infusion of USPIO in 20 patients with breast cancer who were scheduled for surgery, followed by gadolinium-enhanced MR imaging. Lymph nodes were staged prospectively by using newly established criteria, and results were correlated with histologic findings. RESULTS: In two patients, preoperative findings led to a change in therapeutic approach, and neoadjuvant chemotherapy was given; both patients were excluded from statistical analysis. Results of axillary staging with USPIO-enhanced MR imaging were true-positive in nine, true-negative in seven, false-positive in zero, and false-negative in two of 18 patients (sensitivity, 82%; specificity, 100%; positive predictive value, 100%; second reader, kappa = 1.0). Four hundred five lymph nodes were detected with MR imaging. For first and second readers, respectively, lymph node-based sensitivity was 83% and 73% and specificity was 96% and 97% (kappa = 0.68). USPIO as the intravascular contrast agent could not replace gadolinium for assessment of the primary tumor; however, no clinically relevant interaction was seen. Thus, an integrated imaging approach was feasible in all patients. CONCLUSION: USPIO-enhanced MR imaging has the potential to become an adjunct to conventional MR imaging of the breast for preoperative assessment of axillary lymph nodes in patients with breast cancer.

Adult↗

PubMed2002

Radio-frequency ablation of VX2 rabbit tumors: assessment of completeness of treatment by using contrast-enhanced harmonic power Doppler US.

PURPOSE: To assess contrast material-enhanced harmonic power Doppler and fundamental color Doppler ultrasonography (US) in the detection of residual viable tumor tissue after radio-frequency (RF) ablation in tumors embedded in fat. MATERIALS AND METHODS: Twenty-eight VX2 tumors were implanted into the retroperitoneum of 14 rabbits. Tumors were examined with contrast-enhanced fundamental color Doppler US and harmonic power Doppler US before and 10 minutes after RF ablation. Saline-enhanced RF ablation (30 mL/h) was performed over 10 minutes with 28-W RF power. Follow-up included repeat US examinations. Necropsies and histopathologic assessment were performed after detection of residual untreated tumor at US or 3 weeks after ablation. RESULTS: VX2 tumors reached a mean size of 21 mm +/- 9 (SD) (size range, 6-43 mm) 25 days after implantation. All tumors larger than 31 mm showed signs of central necrosis at US. Before ablation, intense vascularity was detected in all tumors with both contrast-enhanced US modes. Histopathologic assessment at the end of the follow-up period revealed local relapses due to incomplete ablation in 14 (50%) of 28 cases. Detection of residual tumor was missed in all cases with contrast-enhanced color Doppler US. Contrast-enhanced harmonic power Doppler US depicted residual flow in 12 of the 14 cases (sensitivity, 86%) in which local relapses occurred. There was a significant (P <.005, McNemar test) improvement in detection of residual tumor when the harmonic power Doppler mode was used. CONCLUSION: Contrast-enhanced harmonic power Doppler US has greater sensitivity than contrast-enhanced color Doppler US for detecting residual VX2 tumor following ablation. Therefore, contrast-enhanced harmonic power Doppler US may be a useful additional method for the detection of residual tumors after RF ablation.

Animals↗

PubMed2002

MR obstetric pelvimetry: effect of birthing position on pelvic bony dimensions.

OBJECTIVE: The aim of our study was to measure the impact of supine and upright birthing positions on MR pelvimetric dimensions. MATERIALS AND METHODS: MR pelvimetry was performed in 35 nonpregnant female volunteers in an open 0.5-T MR imaging system with patients in the supine, hand-to-knee, and squatting positions. The obstetric conjugate; sagittal outlet; and interspinous, intertuberous, and transverse diameters were compared among positions. RESULTS: With patients in the hand-to-knee and squatting positions, the sagittal outlet (11.8 +/- 1.3 cm and 11.7 +/- 1.3 cm) exceeded that in the supine position (11.5 +/- 1.3 cm; p = 0.002 and p = 0.01, respectively), as did the interspinous diameter (11.6 +/- 1.1 cm and 11.7 +/- 1.0 cm vs 11.0 +/- 0.7 cm; p < 0.0001, in both cases). Intertuberous diameter was wider with patients in the squatting position than in the supine position (12.7 +/- 0.8 cm vs 12.4 +/- 1.1 cm; p = 0.01). Only the obstetric conjugate was smaller with patients in the upright squatting position than in the supine position (12.3 +/- 0.8 cm vs 12.4 +/- 0.9 cm; p = 0.01). Transverse diameter did not change significantly in any position. CONCLUSION: An upright birthing position significantly expands female pelvic bony dimensions, suggesting facilitation of labor and delivery.

Adult↗

PubMed2002

Accuracy of image coregistration of pulmonary lesions in patients with non-small cell lung cancer using an integrated PET/CT system.

UNLABELLED: The purpose of this study was to evaluate the accuracy of image coregistration of PET and CT (PET/CT) images in patients with lung lesions and the influence of the breathing protocol during CT. METHODS: Seventy-five patients with a solitary and well-circumscribed pulmonary lesion (non-small cell lung cancer; size, 10-30 mm) underwent PET/CT on a combined scanner. CT was acquired during shallow breathing in 37 patients and during normal expiration (i.e., the level reached when the patient exhaled without forcing expiration and then held the breath) in 38 patients. The volume of interest of each lesion was defined separately on PET and CT images, and the geometric center of gravity (COG) was assessed. The distance of COGs between the PET image and the CT image was measured. All lesions were classified according to 4 lung regions: apical, peripheral, central, and lung base. The mismatch between COG(PET) and COG(CT) was compared between regions and patient groups using a 2-way ANOVA with the Bonferroni-Dunn test for post hoc comparisons. RESULTS: The range of COG distance between PET and CT was 1.7-5.4 mm in the apex, 0.5-14.7 mm in the periphery, 0.7-5.9 mm centrally, and 2.9-11.3 mm in the lung base. The match between PET and CT was significantly better in patients who had the CT scan obtained during normal expiration than in patients who performed shallow breathing during CT scanning (P = 0.024). No reciprocal effects were found (interaction P = 0.76). The mismatch of lesions depends significantly on lung region (P < 0.0001). Post hoc analysis showed a significant difference between the upper 2 regions and the lower 2 regions (all P < or = 0.002) but not between the apex and the central region (P = 0.95) and between the peripheral region and the lung base (P = 0.15). The lesion size had no influence on the COG mismatch. CONCLUSION: The match of lung lesions in coregistered PET/CT images is better when acquiring the CT scan during normal expiration. The coregistration accuracy is better in the upper and central parts of the lung. The normal expiration protocol is suggested to be superior to shallow breathing during CT scanning.

Adolescent↗

PubMedDate not supplied

Comparison of the incidence and predicted risk of early surgical site infections after breast reduction.

In plastic surgery, clean, elective operations such as breast reductions are anticipated to have low risk factors for infections (1.1-2.1%). To further lower or prevent surgical site infections (SSI), the efficacy of a prophylactic administration of anti-microbacterials remains a current controversial issue in plastic surgery. We report here the findings of a retrospective study in which we examined two groups of patients with breast reductions, one of which received a single-shot antimicrobacterial prophylaxis with cefuroxime preoperatively and the other who were given no anti-microbacterials. The aims were to determine the early SSI incidence of both groups, to classify breast reductions with respect to their inherent SSI risk by two widespread, combined risk scores, i.e., the National Nosocomial Infection Surveillance (NNIS) score and the Study on the Efficacy of Nosocomial Infection Control (SENIC) score, and to compare the actual SSI incidence to the predicted risk of the scores. In the divisions of plastic surgery at two hospitals, 153 patients (group I) and 136 patients (group II) could be included in the study in the 4-year period April 1997 to December 2001. Excluded were all patients with unilateral breast reduction or breast reconstruction and patients who were followed up less than 30 days postoperatively. The two groups were comparable with respect to demographic and clinical features such as age and risk factors, and there were no detectable significant intergroup differences in the general perioperative data. According to the NNIS and the SENIC scores, all operations were "clean," and the American Society of Anesthesiologists (ASA) score was < 3 in all patients. Although the mean duration of the operation was significantly different in the two groups (190 min in group I, 160 min in group II; p < 0.001, Mann-Whitney test; 75th percentile at and 4 and 3 h, respectively), it was longer than 2 h in both groups. The incidence of early infections was 3.9% in the first group, compared with 3.6% in the second group (p = 1.0, odds ratio = 1.07, 95% CI = 0.32-3.6). All infections were local and superficial; no general symptoms were noticed. Three patients had to be readmitted and two of these were reoperated. The rate of infections for both groups was higher than generally anticipated for this kind of clean operations and higher than predicted by the NNIS score for medium risk (predicted risk of 2.9%). The reason for this discrepancy is that the NNIS score is an inpatient risk score which does not include a postdischarge SSI surveillance. Using the NNIS definition of SSI we would have had an infection rate of 0% in both groups in our study. According to the SENIC score, breast reductions can be classified also as medium risk of SSI with a predicted risk of 3.9%, which showed a nearly perfect correspondence with the actual SSI incidence in both study groups. The reason for this increased, medium risk is the factor "operation time > 2 h," which is obviously an inherent risk factor in breast reductions. Among the multitude of patient and nonpatient SSI risk factors, in healthy women operation time was the only factor which could be clearly identified.

Adolescent↗

PubMedDate not supplied

Gender and noninvasive diagnosis of coronary artery disease in women and men.

OBJECTIVES: The purpose of this prospective study was to investigate the impact of the gender of physicians and patients on the accuracy of diagnosing coronary artery disease (CAD) based on the patient history only. METHODS: Screening involved 1082 consecutive patients undergoing coronary angiography for suspected CAD. Known CAD was an exclusion criterion. The inclusion criteria were met by 144 patients (47 females). All patients were inverviewed by both an experienced male cardiologist (n=6) and an experienced female cardiologist (n=5), who had to state before coronary angiography if CAD was present relying solely on the patient interview. Eligible subjects also answered a questionnaire. Diagnostic performance to assess the presence or absence of CAD by history taking by male and female cardiologists, exercise testing, patient self-assessment, and the questionnaire were compared. RESULTS: Coronary angiography showed significant CAD in 20 females (43%) and 70 males (72%). Diagnostic accuracy was not different between male (79%) and female (79%) cardiologists and comparable to the results of exercise testing (74%) but better than self-assessment by the patients (65%, p=0.01) or a questionnaire (68%, p=0.01). The accuracy of female physicians was better in men than in women (85% vs. 66%, p=0.01). The specificity of male physicians tended to be better in women than in men (74% vs. 59%, p=0.25). Female cardiologists overestimated the presence of CAD in women (specificity 48% vs. 74%, p=0.04). CONCLUSIONS: The female cardiologists did not assess women more accurately than did their male colleagues. The diagnostic accuracy of these male and female cardiologists was quite good. However, both tend to assess patients of the opposite gender more specifically. There may be an impact of the gender of the physician on the accuracy of diagnosis of CAD by history taking.

Clinical Competence↗

PubMedDate not supplied

Autologous cultured keratinocytes on porcine gelatin microbeads effectively heal chronic venous leg ulcers.

We have established a specific bioreactor microcarrier cell culture system using porcine gelatin microbeads as carriers to produce autologous keratinocytes on a large scale. Moreover, we have shown that autologous keratinocytes can be cultured on porcine collagen pads, thereby forming a single cell layer. The objective of this study was to compare efficacy and safety of autologous cultured keratinocytes on microbeads and collagen pads in the treatment of chronic wounds. Fifteen patients with recalcitrant venous leg ulcers were assigned to three groups in a single-center, prospective, uncontrolled study: five underwent a single treatment with keratinocyte monolayers on collagen pads (group 1); another five received a single grafting with keratinocyte-microbeads (group 2); and the last five received multiple, consecutive applications of keratinocyte-microbeads 3 days apart (group 3). All patients were followed for up to 12 weeks. By 12 weeks, there was a mean reduction in the initial wound area of 50, 83, and 97 percent in the three groups, respectively. The changes in wound size were statistically significant between the first and third groups (p= 0.0003). Keratinocyte-microbeads proved to be more effective than keratinocyte monolayers on collagen pads when the former were applied every 3 days. Rapid availability within 10-13 days after skin biopsy and easy handling represent particular advantages.

Adult↗