Are we going to talk with our anaesthesia monitors in the future?
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Anesthesiology↗
Biomedical subjects
M Weiss
Publications and source records attributed to M Weiss.
Non-invasive monitoring of haemoglobin concentration in paediatric surgical patients using near-infrared spectroscopy.
We evaluated the near-infrared spectroscopy based tissue haemoglobin index for continuous non-invasive monitoring of haemoglobin concentration during paediatric surgery. Blood samples from 40 children (from birth to 16 years old) were analysed oximetrically. From the first blood sample the tissue haemoglobin index/haemoglobin concentration coefficient was calculated for further tissue haemoglobin index-derived haemoglobin concentrations in each patient. Comparison of corresponding values revealed a bias and precision of -0.02 and 5.41 g.l(-1), respectively. Sensitivity and specificity of tissue haemoglobin index were 73.1% and 70.0%, respectively, for predicting falling haemoglobin concentration values. Currently, the tissue haemoglobin index is not suitable for monitoring haemoglobin concentration in children undergoing surgery.
Adolescent↗
Accurate continuous drug delivery at low infusion rate with a novel microvolumetric infusion pump (MVIP): pump design, evaluation and comparison to the current standard.
Infusion devices for continuous and precise drug administration are indispensable tools in anaesthesia and critical care medicine. Problems such as start-up delays, non-continuous flow and susceptibility to hydrostatic pressure changes at low infusion rates resulting in accidental bolus release or prolonged flow interruption are inherent to current infusion technology. In order to improve precise drug delivery, an innovative technical concept has been realised in a novel microvolumetric infusion pump (MVIP) device. The MVIP principle includes repeated filling and emptying of a non-compliant microsyringe without the use of valves. The performance of the MVIP prototype has been evaluated and compared with standard syringe infusion pump assemblies. The novel MVIP concept has thereby proven to eliminate most problems during infusion start-up, steady state flow and vertical pump displacement, and has the potential of revolutionising infusion technology and setting a new dimension in patient safety.
Drug Administration Schedule↗
Rat duodenal IRP1 activity and iron absorption in iron deficiency and after HO perfusion.
BACKGROUND: Iron regulatory protein 1 (IRP1), a post-transcriptional regulator of iron metabolism, is activated in the duodenum of iron-deficient animals, which is associated with increased iron absorption. In cell cultures IRP1 was also activated by iron-independent signals, such as H(2)O(2). Here we investigate whether luminal perfusion of rat duodenum with H(2)O(2) activates duodenal IRP1 and modulates duodenal iron absorption. METHODS: Duodena from iron-adequate Sprague-Dawley rats were luminally perfused with H(2)O(2). Iron regulatory protein-1 activity was determined in duodenal mucosa or in villus and crypt preparations by an electrophoretic mobility shift assay. Duodenal (59)Fe absorption was measured in isolated, perfused duodenal segments ex vivo and in ligated loops in vivo. (59)Fe uptake from the blood side was assessed after i.v. injection of (59)Fe-nitrilotriacetic acid. RESULTS: Similar to iron deficiency, the perfusion with 0-50 mM of H(2)O(2) increases duodenal IRP1 activity along the entire crypt villus-axis in a dose-dependent manner. After H(2)O(2) treatment, IRP1 remains activated for 12-24 h in the tips and for 72 h in the crypts. In iron-deficiency, IRP activation correlates with increased (59)Fe absorption. However, the H(2)O(2) treatment fails to stimulate any increase in (59)Fe uptake, without promoting damage of mucosal architecture or impairing glucose and water transport. CONCLUSION: Duodenal (59)Fe uptake is not affected by the H(2)O(2)-mediated activation of IRP1.
Absorption↗
Measurement of activated clotting time in children--comparison of the Celite i-STAT ACT with the Medtronic ACT II.
BACKGROUND: To evaluate a recently introduced blood-saving method for the measurement of activated clotting time (ACT), the Celite i-STAT ACT, by comparing the values obtained with those from the widely used Medtronic ACT II device. METHODS: In a prospective clinical study, we compared ACT values from the i-STAT device with the Medtronic ACT II device in 60 paediatric, interventional, cardiac catheterization procedures necessitating prophylactic heparinization. Blood samples were pair-analyzed using two i-STAT analyzers and one Medtronic ACT II device with double-tube-cartridges before and after heparinization. Data were compared using Bland-Altman bias analysis, Student's t-test and simple regression analysis. RESULTS: Bias and precision between the Medtronic ACT II and the i-STAT ACT values was -5.4 +/- 26.3. The i-STAT and Medtronic ACT II values were similar before heparinization (P = 0.22), but i-STAT ACT values became significantly longer than Medtronic ACT II values after heparinization (P = 0.021). The increase of ACT after heparinization was greater (median 86.3; range 40-187 s) in the i-STAT analyzer than in the Medtronic ACT II analyzer (median 73.0; range 19-235.5 s). Increase in ACT values was inversely affected by intraoperative haemoglobin concentration in the Medtronic ACT II analyzer (P = 0.001) but not in the i-STAT analyzer. CONCLUSION: Activated clotting times obtained from the Celite i-STAT ACT and the Medtronic ACT II demonstrated poor agreement. The technical principles are quite different and the two methods showed diverse susceptibility to intraoperative haemoglobin concentration. Users have to be aware of technique-specific ACT target ranges and their confounders, which need to be provided by the manufacturers.
Adolescent↗
Caution when using cuffed tracheal tubes for fibreoptic intubation through paediatric-sized laryngeal mask airways.
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Child↗
Nitrous oxide diffusion into tracheal tube cuffs: comparison of five different tracheal tube cuffs.
BACKGROUND: The aim of this study was to investigate cuff compliance and cuff pressure during nitrous oxide exposure in the recently introduced Microcuff tracheal tube with a polyurethane cuff (Microcuff GmbH, Weinheim, Germany), and to compare it to conventional tracheal tubes with PVC cuffs. METHODS: In an in vitro set up, five cuffed tracheal tubes (ID 7.0 mm) from different manufacturers (Microcuff HVLP, Portex Profile Soft Seal, Mallinckrodt HiLo, Rüsch Super Safety Clear and Sheridan CF) were studied. Pressure-volume curves were assessed and changes of cuff pressure during exposure to nitrous oxide (for 60 min; 66% N(2)O in oxygen) were recorded without and with restriction of the cuff in a trachea model. Each experiment was performed four times using two exemplars of each tube twice. Sixty-minute values of the Microcuff group were compared with the other groups using the Mann- Whitney test (P < 0.05). RESULTS: The Microcuff polyurethane cuff demonstrated an intermediate cuff compliance but the highest cuff pressure increase during nitrous oxide exposure under unrestricted conditions. When inflated within the artificial trachea its cuff compliance became the highest of all tested tracheal tubes. However, exposure to N(2)O, again led to a rapid increase in cuff pressure. CONCLUSION: The ultra-thin polyurethane tube cuff demonstrated higher permeability for nitrous oxide than conventional PVC cuffs and led to a rapid cuff pressure increase when exposed to N(2)O. Routinely checking of cuff-pressure or filling the cuff with nitrous oxide are more important than the brand of tube used.
Air Pressure↗
Swab cultures accurately identify bacterial pathogens in diabetic foot wounds not involving bone.
AIMS: Current clinical practice assumes swab cultures from wounds are unreliable. However, this assumption is based upon data culled only from wounds in which osteomyelitis and/or gangrene were present. This study aimed to re-evaluate the accuracy of swab cultures vs. deep tissue cultures in diabetic wounds of varying depth and severity. METHODS: A total of 60 infected diabetic foot wounds were cultured. Two specimens were taken from each wound: superficial swab before debridement and deep tissue specimen towards the end of surgical debridement. RESULTS: In 37 wounds (62%), the micro-organisms isolated from the swab specimen and those isolated from the deep tissue specimen were identical. In another 12 wounds (20%), the swab culture contained all micro-organisms isolated from the deep tissue culture, but also contained additional micro-organisms. Analysis according to the depth of the wound, demonstrated that swabs identified all micro-organisms isolated from the deep tissue specimens in 36/40 wounds (90%) that did not extend to bone as opposed to 13/20 wounds (65%) that extended to bone. CONCLUSIONS: Swab cultures are valuable in identifying pathogens in diabetic foot wounds when bone is not involved. When surgical debridement is contraindicated or delayed, swab cultures can be used to select appropriate antibiotic therapy.
Adult↗
Screening instruments for general hospital and primary care patients.
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Anxiety Disorders↗
[First experiences with a new radiopharmaceutical for sentinel lymph node detection in malignant melanoma: (99m)Tc colloidal rhenium sulphide].
UNLABELLED: AIM of this study was to localize the sentinel lymph node by lymphoscintigraphy using technetium-99m colloidal rhenium sulphide (Nanocis), a new commercially available radiopharmaceutical. Due to the manufacturers' instructions it is licensed for lymphoscintigraphy. PATIENTS AND METHODS: 35 consecutive patients with histologically proved malignant melanoma, but without clinical evidence of metastases, were preoperatively examined by injecting 20-40 MBq Nanocis with (mean particle size: 100 nm; range: 50-200 nm) intradermally around the lesion. Additionally blue dye was injected intraoperatively. A hand-held gamma probe guided sentinel node biopsy. RESULTS: During surgery, the preoperatively scintigraphically detected sentinel lymph nodes were identified in 34/35 (97%) patients. The number of sentinel nodes per patient ranged from one to four (mean: n = 1.8). Histologically, metastatic involvement of the sentinel lymph node was found in 12/35 (34%) patients; the sentinel lymph node positive-rate (14/63 SLN) was 22%. Thus, it is comparable to the findings of SLN-mapping using other technetium-99m-labeled nanocolloides. CONCLUSION: (99m)Tc-bound colloidal rhenium sulphide is also suitable for sentinel node mapping.
Adult↗
[Acquisition of age- and sex-dependent patient data for the calculation of annual radiation exposure in nuclear medicine: a German pilot study].
AIM: A pilot study for estimation of radiation exposure due to diagnostic procedures in nuclear medicine using routine data of hospitals and practices in Germany. METHODS: Hospitals and practices willing to participate in the study supplied data of one year (1997), containing information on patients' identification number, age, sex, type of diagnostic procedure, radiopharmaceutical, administered activity, type of health insurance (private/public), inpatient/outpatient status, and so-called Leistungsziffer, which describes the type of medical performances in Germany. The effective dose per examination was calculated according to ICRP 80. Mean, standard deviation, median, 5th and 95th percentiles of the effective dose were calculated, stratified by type of organ system and also by sex and age, including patients of > or = 18 years. RESULTS: 82,039 examinations from patients of 9 hospitals and practices were analyzed. The median (5-95(th) percentiles) of the effective dose per examination for all patients was 2.9 mSv (0.4-8.5 mSv); 1.2 examinations per patient and year were performed on average. The three most frequent examinations were bone scans (median 3.4 mSv; 2.9-5.1), thyroid (0.9 mSv; 0.4-2.2) and cardiovascular studies (7.3 mSv; 3.8-20.2). The median effective dose for 18 to 40 years old women was 1.0 mSv (0.4-5.8), for women between 41 and 65 years 2.2 mSv (0.4-7.3) and for women older than 65 years 2.4 mSv (0.5-7.6). The corresponding values for men were 2.6 mSv (0.3-7.6); 3.3 mSv (0.4-9.1), and 3.4 mSv (0.5-8.8). CONCLUSION: It was possible to gain an accurate determination of radiation exposure of diagnostic procedures in nuclear medicine by routine data.
Adult↗
[Diagnosis of initial changes in patients suffering from rheumatoid arthritis. Two years follow up control with a low-field magnetic resonance scanner, 3-phase bone scintigraphy and conventional x-ray].
UNLABELLED: Besides conventional x-ray, in the diagnostic work up of initial changes in patients suffering from rheumatoid arthritis (RA), 3-phase bone scintigraphy (3P-Sz) is as well established as magnetic resonance imaging (MRI). The AIM of this study was to compare the diagnostic value of a newly developed low field MRI with proven methods such as conventional x-ray and 3P-Sz. PATIENTS, METHODS: 42 patients were studied using a one days protocol with 3P-Sz, MRI, and x-ray of the hands with yearly follow up examinations. Images were visually assessed by two blinded nuclear medicine physicians and radiologists and classified as RA-typical and non-RA-typical changes. All methods were compared to the summarised findings interpreted by a rheumatologist in consideration of the Ritchie articular index as gold-standard. RESULTS: 24/42 patients presented with clinical symptoms of initial changes by rheumatoid arthritis. Conventional x-ray revealed in 20/24 patients within the correct diagnosis in the study period. On the other hand 3P-Sz and low field MRI concordantly showed all 24 patients with initial changes due to RA. Time of detection showed variations with a tendency to later findings by conventional x-ray. CONCLUSIONS: In the diagnostic work up of initial changes conventional x-ray should be the first choice in imaging. Our findings suggest that MRI represents an equally sensitive method for the diagnosis of initial changes due to RA in the region of the hands as compared to the 3P-Sz. The limitation of the low field MRI is the small field of view, so we prefer 3P-Sz or high field MRI in the diagnosis of patients with suspected RA.
Arthritis, Rheumatoid↗
The effects of FSH and of testosterone on the completion of meiosis and the very early steps of spermiogenesis of the rat: an in vitro study.
The role of FSH and of testosterone in spermatogenesis has been a matter of controversy. In the present study, we addressed the involvement of these hormones in the regulation of the completion of meiosis of male rats under in vitro conditions. In the first series of experiments, middle/late pachytene spermatocytes were cocultured with Sertoli cells for 2 weeks in the absence or presence of FSH and/or testosterone. Treatment with both FSH and testosterone reduced slightly the percentage of apoptotic germinal cells in the cultures. Moreover, the number of round spermatids formed in vitro was enhanced by FSH or testosterone when compared with control cultures. Neither hormone influenced the half-life of round spermatids under the present culture conditions. The amounts of TP1 mRNAs in FSH- or FSH plus testosterone-treated cultures were higher than those of controls. In another series of experiments, round spermatids were incubated for 24 h in media conditioned by Sertoli cells cultured in the absence or presence of FSH and/or testosterone. TP1 mRNA contents of round spermatids incubated in media from Sertoli cells cultured in the presence of FSH and/or testosterone were two- to threefold higher than those of spermatids incubated in media from Sertoli cells cultured without hormones. These results indicate that FSH and testosterone have positive and somewhat overlapping effects on the meiotic divisions and the post-meiotic expression of a germ cell-specific gene, effects which cannot be related solely to their ability to reduce germinal cell apoptosis. Use of this culture system should help to test the effect of any hormone or factor on those steps in order to understand better their regulation.
Animals↗
Normal p21Ras/MAP kinase pathway expression and function in PBMC from patients with polycystic ovary disease.
Polycystic ovary disease (PCOD) is associated with insulin resistance and increased prevalence of type II diabetes mellitus (T2DM). The p21Ras/MAP kinase is a major intracellular signaling pathway mediating insulin signaling in insulin responsive tissues. The expression, regulation and function of the p21Ras/MAP kinase pathway in PCOD patients were examined. Peripheral blood mononuclear cells (PBMC) were isolated from ten patients with PCOD and ten controls. The expression of p21Ras and its regulatory proteins; hSOS1 and p120GAP were studied. The basal and phytohemaglutinin (PHA) or insulin stimulated phosphorylation of MAP kinase was determined. Expression of p21Ras, and its regulatory proteins hSOS1 and p120GAP were similar in PCOD patients and controls. Basal, PHA and insulin stimulated phosphorylation of MAP kinase, were also comparable in the two groups as well as their PBMC proliferative response. These data indicate that the expression and overall function of the p21Ras/MAP kinase pathway remain intact in non-diabetic patients with PCOD.
Adult↗
Chronic idiopathic myelofibrosis: prognostic impact of myelofibrosis and clinical parameters on event-free survival in 122 patients who presented in prefibrotic and fibrotic stages. A retrospective study identifying subgroups of different prognoses by using the RECPAM method.
In chronic idiopathic myelofibrosis (CIMF) the factors predicting survival in patients who were already in the fibrotic stage have been well documented by numerous studies. Prefibrotic stages were only rarely evaluated so that the prognostic impact of myelofibrosis is currently not well known. Also predictive factors for disease-related events were not included in those studies. Thus, we evaluated the prognostic impact of myelofibrosis and other histopathological (megakaryocytes, blasts) and clinical [age, gender, splenomegaly, chemotherapy, hemoglobin (Hb), leukocyte, and platelet count] parameters in 122 patients in fibrotic and prefibrotic stages of CIMF on event-free survival. The statistical analysis was performed using the univariate log-rank test and the multivariate recursive partition and amalgamation (RECPAM) approach. In 62 patients disease-related events occurred during a mean observation period of 58 months. In univariate analysis they were associated with blast increase in the bone marrow. In RECPAM analysis a shorter event-free survival was found in anemic patients (mean: 9.3 months). In nonanemic patients older than 60 years, advanced myelofibrosis was associated with a shorter event-free mean survival of 23.2 months versus 69.3 months in less advanced cases. A slight or moderate myelofibrosis was not found to have a prognostic impact on event-free survival. The longest event-free survival was found in nonanemic patients who were younger than 60 years (mean: 185 months), regardless of the grade of myelofibrosis. Thus, we found that the most relevant prognostic parameter for event-free survival in CIMF were the Hb value, age, and grade of myelofibrosis.
Adult↗
[49-year-old patient with staphylococcal endocarditis and thyrotoxic crisis].
We report the case of a 49-year-old woman who presented with typical features of thyroid crisis. Besides the confirmation of severe thyreotoxicosis a native valve endocarditis due to Staphylococcus aureus was diagnosed. Diagnostic criteria and therapies of these life-threatening disorders are discussed and a possible association in the present case is evaluated.
Diagnosis, Differential↗
Can simple renormalization theories describe the trapping of chaotic trajectories in mixed systems?
We investigate the relation between the chaotic dynamics and the hierarchical phase-space structure of the standard map as an example for generic Hamiltonian systems with a mixed phase space. We demonstrate that even in ideal situations when the phase-space structure is dominated by a single scaling, the long-time dynamics is not dominated by this scaling. This has consequences for the power-law decay of correlations and Poincaré recurrences.
Journal Article↗