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B Zernikow

Publications and source records attributed to B Zernikow.

32 records · Page 2Linked to original sources

[Edeka does all--machine speech recognition in social medicine expert testimony].

UNLABELLED: Automatic speech recognition systems are already being used in spheres employing a restricted vocabulary. OBJECTIVE: Our aim was to investigate whether low-cost speech recognition software for PC is capable of being usefully employed in the sphere of sociomedicine. MATERIALS AND METHODS: To this end 34 representative pages of text (a total of 11,000 words) taken from expertises on cases of suspected medical malpractice (many different subspecialties) were dictated using IBM's "Voice Type Simply Speaking" software. Having completed a page, the resulting error rate was recorded, and the text was corrected before we proceeded with the dictation. Finally, 3 pages of text were re-dictated and the resulting error rate determined. RESULTS: The error rate in the previously unknown text ranged between 10 and 23 per cent (mean 15.9%) without any significant reduction during the training phase, while that in the re-dictated text was drastically reduced to less than 3 per cent. It became evident that once a word was corrected the system hardly ever repeated that particular mistake. CONCLUSION: The system's poor performance on unknown text and the missing reduction in the error rate during the training phase are obviously not due to any incompetence of the system but to the huge amount of technical jargon in the scope of medical writing. To attain an acceptable performance we suggest to either extend the training phase, or, preferably, to confine the application to a single medical subspecialty. Its overwhelming learning ability makes the system a serious candidate typist in the sphere of sociomedicine.

Expert Testimony↗

Frequency dependence of cerebrovascular impedance in preterm neonates: a different view on critical closing pressure.

The nonproportional relationship between instantaneous arterial blood pressure (BP) and cerebral blood flow velocity (CBFv) is well explained by the concept of critical closing pressure (CCP). We aimed to determine the frequency response of the neonatal cerebrovascular system, and to establish the exact mathematical relationship between cerebrovascular impedance and CCP under physiologic conditions. In 10 preterm neonates (gestational age, 25-32 weeks; birth weight, 685-1,730 g; age 1-7 days) we Doppler-traced CBFv of the internal carotid artery. Blood pressure was traced simultaneously. Critical closing pressure was graphically determined. Cerebrovascular impedance was calculated as the square root of the ratio of the corresponding peaks in the power spectra of BP and CBFv at zero frequency, and at heart rate (H) and harmonics (xH). Uniformly, the impedance between H and 3H (2 to 6 Hz) was reduced about fivefold, compared with the impedance at zero frequency. The cerebrovascular system behaves like a high-pass filter, leading to a reduction of the DC (direct current) component of CBFv (analogous to current) relative to that of the driving force BP (analogous to voltage). The frequency response of cerebrovascular impedance reflects the ratio of CCP and DC BP. A mathematical derivation of this relationship is given matching the observed results. Thus, both the CCP and the impedance approach are valid.

Birth Weight↗

Cyanotic Raynaud's phenomenon with conventional but not with liposomal amphotericin B: three case reports.

Despite its common adverse effects intravenous (i.v.) amphotericin B is an indispensable antifungal drug in childhood oncology. We report here on three cases of painful cyanotic Raynaud's phenomenon after i.v. administration or inhalation of amphotericin B. A liposomal i.v. preparation of amphotericin B was well tolerated by the infants. Spasms of peripheral vessels mediated by thromboxane A2 could be responsible for the Raynaud's phenomenon. Hence, inhibitors of prostaglandin synthesis are suggested for therapy.

Administration, Inhalation↗

Ventilator-associated sinus arrhythmia in a preterm neonate--an indicator for a mature autonomic nervous system?

According to control theory, the interactions between respiration and heart rate (i.e. respiratory sinus arrhythmia, RSA, and breath amplitude sinus arrhythmia, BASA) reflect the inner workings of the physiological control systems of respiration and circulation. This paper reports on a preterm neonate (28.5 weeks old, 940 g) who showed the presence of ventilation-associated sinus arrhythmia (VASA) under moderate artificial ventilation. His heart rate variability was entrained to the ventilatory stimulus. VASA and entrainment suggest that the parasympathetic part of the autonomic nervous system might be more mature than expected in some preterm neonates.

Arrhythmia, Sinus↗

Critical closing pressure in preterm neonates: towards a comprehensive model of cerebral autoregulation.

In preterm neonates, intraventricular haemorrhage is linked to the dysfunction of cerebral autoregulation (AR). We aimed at tracing the critical closing pressure (CCP) in order to quantify AR and to reveal its inner workings. In an observational study, 10 preterm neonates (median, range: ga 28 weeks, 25 to 32 weeks; bw 1070, 685 to 1730 g; age 2d, 1 to 7 d) were continuously Doppler traced (a. carotis interna) for > 10 min. Systemic blood pressure (BP, a. umbilicalis, a. radialis, a. temporalis) was recorded simultaneously (> 1200 cardiac cycles each). Systolic BP was on average 11 mmHg above CCP. There was a striking parallel between both variables, even in cases of sudden spontaneous BP fluctuations > 30% (r = 0.72, 0.41 to 0.99), while systolic cerebral blood flow velocity remained largely unaffected (r = -0.15, -0.75 to 0.53), indicating a properly functioning AR. CCP was 28 mmHg, 14 to 38 mmHg. Based on our data, a physiological model of AR is developed, integrating anatomy, metabolic and neuronal pathways with former physiologic findings--including low frequency cycling of cerebral blood flow velocity. Tracing of CCP is thought to have the potential to identify infants with impaired AR. Since this method is noninvasive and independent of angle of insonation (thus rendering it uncritical in probe fixation), it is a promising tool for sustained monitoring of cerebral haemadynamics in the clinical setting.

Blood Flow Velocity↗

Cyclic variation pattern of cerebral blood flow velocity and postconceptional age.

In preterm neonates, the risk for intracerebral haemorrhage is linked to immaturity of cerebral autoregulation. The preterm's 2-5/min cyclic variation pattern of cerebral blood flow velocity is thought to reflect the degree of immaturity of autoregulation--a speculation to be tested. In a cross-sectional study 15 infants (gestational age 26-40 weeks, postconceptional age (PCA) 26-42 weeks, age 1-99 days were investigated. We performed a 10 min pulsed Doppler tracing on an internal carotid artery by means of a computer controlled 5 MHz Duplex device. Systolic velocity (Vs) was recorded pulse by pulse. After appropriate data transformation, in all infants the Fast Fourier Transform of the time course of Vs revealed the presence of a 2-5/min cyclic variation pattern (one sample z-test, P < 0.0001). There was no significant correlation between proportionate spectral power of the 2-5/min frequency band and either PCA (r = 0.23, P = 0.42) or age (r = 0.41, P = 0.13). Between 26 and 42 weeks PCA, the cycling phenomenon is constant thus not reflecting cerebral maturation, and its presence does not mean immaturity of cerebral autoregulation.

Age Factors↗

Cerebral autoregulation of preterm neonates--a non-linear control system?

The low frequency cerebral blood flow velocity (CBFV) oscillations in neonates are commonly attributed to an under-dampened immature linear type cerebral autoregulation, and the 'instability' is regarded as causative for peri-intraventricular haemorrhage/periventricular leukomalacia. In contrast, oscillations susceptible to frequency entrainment are a fundamental part of the stable function of non-linear control systems. To classify the autoregulation an observational study was done on the relationship between CBFV oscillations, heart rate variability, and artificial ventilation. In 10 preterm neonates (gestational age 26 to 35 weeks) we serially Doppler traced arterial CBFV continuously for 12 minutes between days 1 and 49 of life. The individual time series of CBFV and heart rate were subjected to spectral analysis. Forty six of 47 tracings showed significant low frequency CBFV oscillations. Low frequency heart rate oscillations were not a prerequisite thereof. All patients with < 30% of total power in the low frequency band of CBFV oscillations were on the ventilator. Three of them demonstrated a shift of spectral power from low frequency to a frequency equal or harmonic to the ventilator rate indicating entrainment. The findings of CBFV oscillations combined with entrainment classify the autoregulation as a non-linear system. It is suggested that entrainment by periodic high amplitude stimuli might challenge the regulatory capacity to its limits thus increasing the risk for cerebral damage.

Blood Flow Velocity↗

Adaptive multipurpose probe fixation device for use on newborns.

Detailed information on the construction and assembly of a noncommercial hood-like multipurpose probe fixation device is given. A vacuum technique is used to individually mold the device to the skull of newborn infants and to attach sensors firmly with minimum pressure. By design, in the range of 22 to 38 cm head circumference for transfontanellar Doppler monitoring, no more than four different sizes of the hood are required to match individual positions of the anterior fontanelle. A ball-and-socket joint facility is integrated. The flexibility of the design allows for an easy adaptation of the device to different probe requirements. This provides the opportunity to investigate cerebral circulation by using various methods simultaneously.

Blood Flow Velocity↗

Basal and stimulated formation and release of L-arginine-derived nitrogen oxides from cultured endothelial cells.

Endothelium-derived nitrogen oxides, i.e., nitrogen oxide and/or nitrogen oxide-containing compounds, formed from L-arginine account, at least in part, for the biological activity of endothelium-derived relaxing factor(s). We have developed a rapid and sensitive assay to determine the basal and stimulated release of defined breakdown products of endothelium-derived nitrogen oxides, i.e., nitrite and nitrate. Formation and/or release of these nitrogen oxides was time- and concentration-dependently stimulated by various endothelium-dependent vasodilators and was decreased by NG-methyl-L-arginine and L-canavanine, compounds that most likely inhibit the endothelial enzymatic conversion of L-arginine into nitrogen oxides. In addition to nitrogen oxide, hydroxylamine was shown to have pharmacological and physico-chemical properties similar to endothelium-derived relaxing factor(s). Moreover, hydroxylamine release was detected in stimulated bovine aortic endothelial cells. We suggest that hydroxylamine represents one endothelium-derived nitrogen oxide within the group of biologically active nitrogen oxides.

Acetylcholine↗

[Cyanotic Raynaud phenomenon as a side effect of Amphotericin B].

Despite its wellknown adverse effects, Amphoterin B is an integral part of any supportive therapy in haematology/oncology. We report on a thirteen year old boy with acute myelogenous leukemia and suspected fungoid pneumonia. Shortly after iv or inhalative application of Amphotericin B he repeatedly presented with a Raynaud phenomenon of his toes, which ceased after switching to Ambisome (liposomal unilamellar encapsuled Amphotericin B). Since there is evidence that thromboxane A2-mediated arteriolar spasms of renal vessels provoke the wellknown increase in serum creatinine after Amphotericin B, and in different species pulmonal vasoconstriction has been observed, we speculate that a similar mechanism is responsible for the observed Raynaud phenomenon. Thus we suggest inhibitors of prostaglandine synthesis for therapy.

Adolescent↗

[IDA-FLAG (idarubicin, fludarabine, high dosage cytarabine and G-CSF)--an effective therapy regimen in treatment of recurrent acute myelocytic leukemia in children and adolescents. Initial results of a pilot study].

Intensive chemotherapy has improved the prognosis of patients with AML. The success rate of relapse treatment correlates with the length of first remission. Thus early relapses and primarily refractory diseases have a grave prognosis. New chemotherapeutic regimens could be useful for those patients. Patients treated for newly diagnosed or relapsed AML with polychemotherapy regimen of the AML-BFM-studies containing induction, consolidation and high-dose cytarabine combined with mitoxantrone (HAM) and relapsed within 2 up to 31 months after the first CR entered a pilot trial, the so called IDA-FLAG regimen. This regimen includes G-CSF (day 0 up to ANC > 1000/microliter, 400 micrograms/m2.d), fludarabine (day 1-4, 30 mg/m2.d), high-dose cytarabine (day 1-4, 2000 mg/m2.d) and idarubicin (day 2-4, 12 mg/m2.d). 10 patients aged 1,8 to 28,1 years (mean = 9,6 years) having the first (n = 8) or second relapse (n = 1) of AML or an acute blastcrisis of myelodysplastic syndrome (n = 1) (FAB classification: M1/M2 = 3, M4/M5 = 5, M7 = 1, CMML = 1) received 14 courses. Overall, 7 patients achieved CR with a mean duration of 8,9 months (1-22 months), one patient showed a partial remission and two were nonresponders. 4 patients are in continuous CR for 7,5 to 22 months (mean = 13,2 months). 3 patients got a bone marrow transplantation (allogenic = 2, autologous = 1) in CR following this treatment. Toxicity was considerable, mainly bone marrow aplasia with leucopenia < 1000/microliter for 15 to 40 days (mean = 26,1 days), neutropenia < 500/microliter for 14 to 39 days (mean = 26,0 days) and thrombocytopenia < 30,000/microliter for 14 to 90 days (mean = 36,5 days). Further important side effects were fever, mucositis and pneumonia. One patient died from an fulminant aspergillus sepsis during long-term neutropenia. The sequential administration of G-CSF, fludarabine, cytarabine and idarubicin is effective in treatment of relapsed AML in childhood and an advisable option prior to allogenic or autologous bone marrow transplantation. With regard to the unfavorable prognosis of relapsed or refractory AML the toxicity of this regimen seems acceptable.

Adolescent↗

Use of an artificial neural network (ANN) for classifying nursing care needed, using incomplete input data.

BACKGROUND: In German nursing insurance, the act of classifying the client into four categories of disability is based on legally defined distinct criteria. When classifying deceased persons it is often impossible to collect all the required information. PRIMARY OBJECTIVE: We aimed to determine the ability of an artificial neural network (ANN) to calculate the category of disability, to investigate the response of the ANN to input items of different nature, quantity and data quality, and to estimate the minimum number of training data required. RESEARCH DESIGN: The investigation was conducted as a retrospective observational study. METHODS AND PROCEDURES: The analysis was based on routine records of 14000 adult clients of the nursing insurance. Several ANNs were trained, varying nature, number and quality of the input items as well as the size of the training data set. Each ANN's classification competence was tested on independent validation data, judging the ANN's conformance to the result of the individual expert assessment, using kappa statistics. MAIN RESULTS: Fed with all 30 input items available, the net classified 80% of cases correctly (weighted kappa = 0.78). Using three input items, weighted kappa was 0.63. Severe misclassification (deviation by more than one category in either direction) ranged between 0.2% (all 30 input items) and 3.7% (3/30 items). The less complete the individual input items were, the less accurate was the net's estimate. A 20% rate of missing values was well tolerated. A training set comprising 500 cases was adequate. CONCLUSIONS: The input item set inherits redundancy. The ANN's ability to correctly respond to subsets of input items makes it a powerful tool in quality control. In the categorization of deceased persons when only an incomplete input item set is available, the ANN can achieve satisfactory results.

Activities of Daily Living↗