Impact of Skull Thickness on Cerebral NIRS Oximetry in Neonates: An in silico Study.

Monitoring of cerebral tissue oxygen saturation (StO2) by near-infrared spectroscopy (NIRS oximetry) has great potential to reduce the incidence of hypoxic and hyperoxic events and thus prevent long-term disabilities in preterm neonates. Since the light has to penetrate superficial layers (bone, skin and cerebrospinal fluid) before it reaches the brain, the question arises whether these layers influence cerebral StO2 measurement. We assessed this influence on the accuracy of cerebral StO2 values. For that purpose, we simulated light propagation with 'N-layered medium' software. It was found that with a superficial layer thickness of ≤6 mm, typical for term and preterm neonates, StO2 accurately reflects cerebral tissue oxygenation.

Reducing False Alarm Rates in Neonatal Intensive Care: A New Machine Learning Approach.

In neonatal intensive care units (NICUs), 87.5% of alarms by the monitoring system are false alarms, often caused by the movements of the neonates. Such false alarms are not only stressful for the neonates as well as for their parents and caregivers, but may also lead to longer response times in real critical situations. The aim of this project was to reduce the rates of false alarms by employing machine learning algorithms (MLA), which intelligently analyze data stemming from standard physiological monitoring in combination with cerebral oximetry data (in-house built, OxyPrem). MATERIALS & METHODS: Four popular MLAs were selected to categorize the alarms as false or real: (i) decision tree (DT), (ii) 5-nearest neighbors (5-NN), (iii) naïve Bayes (NB) and (iv) support vector machine (SVM). We acquired and processed monitoring data (median duration (SD): 54.6 (± 6.9) min) of 14 preterm infants (gestational age: 26 6/7 (± 2 5/7) weeks). A hybrid method of filter and wrapper feature selection generated the candidate subset for training these four MLAs. RESULTS: A high specificity of >99% was achieved by all four approaches. DT showed the highest sensitivity (87%). The cerebral oximetry data improved the classification accuracy. DISCUSSION & CONCLUSION: Despite a (as yet) low amount of data for training, the four MLAs achieved an excellent specificity and a promising sensitivity. Presently, the current sensitivity is insufficient since, in the NICU, it is crucial that no real alarms are missed. This will most likely be improved by including more subjects and data in the training of the MLAs, which makes pursuing this approach worthwhile.

Comparison of tissue oximeters on a liquid phantom with adjustable optical properties: an extension.

Cerebral near-infrared spectroscopy (NIRS) oximetry may help clinicians to improve patient treatment. However, the application of NIRS oximeters is increasingly causing confusion to the users due to the inconsistency of tissue oxygen haemoglobin saturation (StO2) readings provided by different oximeters. To establish a comparability of oximeters, in our study we performed simultaneous measurements on the liquid phantom mimicking properties of neonatal heads and compared the tested device to a reference NIRS oximeter (OxiplexTS). We evaluated the NIRS oximeters FORE-SIGHT, NIRO and SenSmart, and reproduced previous results with the INVOS and OxyPrem v1.3 oximeters. In general, linear relationships of the StO2 values with respect to the reference were obtained. Device specific hypoxic and hyperoxic thresholds (as used in the SafeBoosC study, www.safeboosc.eu) and a table allowing for conversion of StO2 values are provided.

HPV16 genotype, p16/Ki-67 dual staining and koilocytic morphology as potential predictors of the clinical outcome for cervical low-grade squamous intraepithelial lesions.

OBJECTIVE: To evaluate the association of human papillomavirus (HPV) 16 and non-16 genotype, p16/Ki-67 dual staining and koilocytosis and their role in the prediction of the clinical outcome of low-grade squamous intraepithelial lesion (LSIL) cytology. METHODS: One hundred and fifty-five patients with LSIL were followed up and recorded as progression, persistence or regression. HPV genotyping was performed for high-risk HPV (hrHPV) DNA-positive cases. Koilocytosis was reviewed and p16/Ki-67 dual staining was performed on reprocessed conventional cytology slides. RESULTS: HPV16 was the most frequent genotype found in 16.3% of cases. p16/Ki-67 dual staining was positive in 36.1% of all cases. Progression, including concurrent cervical intraepithelial lesion grade 2 or above (CIN2+), was recorded in 13.8% of cases. A statistically significant difference between progressive and non-progressive cases was shown by the following: hrHPV-positive versus hrHPV-negative (P = 0.022), HPV16-positive versus non-16 HPV-positive (P < 0.001) and p16/Ki-67-positive versus p16/Ki-67-negative (P < 0.001) cases. Cases with combined HPV16 and p16/Ki-67 positivity showed the highest progression rate (58.3%). Non-koilocytic HPV16-positive cases showed a 50% progression rate compared with 10.1% for koilocytic non-16 HPV-positive cases (P = 0.010). The sensitivity of p16/Ki-67 dual staining for the detection of CIN2+ lesions was 80%, comparable with hrHPV (85%). The specificity of p16/Ki-67 dual staining was 71% and of hrHPV 42%. The highest specificity was found for HPV16 genotype presence (91%), but with low sensitivity (50%). CONCLUSION: HPV genotyping, p16/Ki-67 dual staining and koilocytic morphology can be useful in the prediction of clinical outcome in women initially diagnosed with LSIL cytology.

[Validation of continuous blood pressure measurements by pulse transit time: a comparison with invasive measurements in a cardiac intensive care unit]. / Validierung der kontinuierlichen nicht-invasiven Blutdruckmessung mittels Puls-Transit-Zeit: Ein Vergleich mit der invasiven Blutdruckmessung bei Patienten einer kardiologischen Intensivstation.

BACKGROUND AND OBJECTIVE: Arterial blood pressure measured by pulse transit time (PTT) can be used as an alternative to the gold standard of invasive measurement. It was the aim of this study to compare these two methods in order to validate PTT in patients with cardiac diseases. PATIENTS AND METHODS: In 40 patients (29 males; mean age 68.7 ± 15 years) in a cardiac intensive care unit, blood pressures were continuously measured by PTT and the standardized invasive method for one hour. Values were analysed and compared in 30-second intervals (9,600 values for each method). RESULTS: Blood pressures obtained with either method were not statistically different, neither in the whole group nor in subgroups. However, the number of analysable data was significantly higher using the invasive method, by which appropriate signals were obtained in 99.2 % of systolic and in 99.1 % of diastolic blood pressure measurements. In contrast, using the PTT-method, appropriate signals were seen in 85.8 % of systolic and 85.9 % of diastolic pressure measurements. CONCLUSION: Blood pressures measured by PTT in patients in cardiac intensive care units provide reliable values over a period of at least one hour. However, the PTT method seems to be more susceptible to errors as evidenced by the number of failed measurements.

Exposure to chemical agents in aluminium potrooms.

OBJECTIVES: To assess the effects of modernization of aluminium production on reducing the chemical health hazards in the working environment in aluminium potrooms (smelter). Modernization included the introduction ofa technique of point feeding of alumina and aluminium fluoride into the pots, semi-automatic equipment and computerized control. METHODS: Periodical environmental measurements of chemical substances, dusts containing alumina and fluorides, and gases, i.e., carbon monoxide, carbon dioxide, sulphur dioxide, hydrogen fluoride, nitrogen dioxide, and difluorosulphide, were performed at the same workplaces before (1986-1988) and sixteen years later, after modernization (2004). The measured values were compared with the recommended occupational safety and health standards. RESULTS: The concentrations of total dust (alumina and fluorides) and gases, i.e., carbon monoxide, carbon dioxide, sulphur dioxide, hydrogen fluoride and phenol, were above the recommended standards in 76.6% (95/124) of the samples before modernization and in only 23.8% (57/240) of the samples tested after modernization. Before modernization in almost all jobs the workers were simultaneously exposed to higher concentrations of all chemical agents present in the working environment. After modernization high concentrations of hydrogen fluoride were the primary pollutant in this plant (GM = 4.5451 ppm), while the presence of other gases was significantly reduced. Dusts containing alumina and fluorides and hydrogen fluoride gas were still present in considerable concentrations in the working environments of jobs such as changing and covering of anodes. CONCLUSION: The modernization of the aluminium smelter plant reduced the concentrations of the most harmful substances in the working environment and reduced the number of jobs where workers were simultaneously exposed to a variety of health hazards.

Intraoperative cytology of clear cell carcinoma of the ovary.

OBJECTIVE: To describe the cytomorphology of clear cell carcinoma (CCC) of the ovary in intraoperative samples of peritoneal fluid, imprint and scraping samples of the tumour tissue. STUDY DESIGN: Fourteen histologically confirmed cases, stained by standard cytological procedures, were analysed by light microscopy. RESULTS: In 33.3% of peritoneal fluid samples and 92.9% of imprint and scraping cytological samples, besides variable clear cell cellular morphology, one or both distinct cytological characteristics were observed: eosinophilic, hyaline, extracellular, globular substance with or without formation of a 'raspberry' body and an eosinophilic, intracytoplasmic inclusions. These structures were clearly seen only in samples stained by May-Grünwald-Giemsa. CONCLUSION: Using cytological analysis of imprint and scraping samples of ovarian tumours it is possible to make a precise intraoperative cytological diagnosis in most cases of CCC of the ovary.

Morphometry and digital AgNOR analysis in cytological imprints of benign, borderline and malignant serous ovarian tumours.

AIM: The aim of the study was to determine values of a quantitative morphometry analysis of nuclear characteristics and argyrophilic nucleolar organizer regions (AgNORs) in differential cytodiagnosis of benign, atypically proliferating (borderline) and malignant serous ovarian tumours. METHODS: Cytological imprints of benign (n = 20), borderline (n = 19) and malignant (n = 20) ovarian serous tumours were analysed. A computerized, digital analysis was used to determine morphometric nuclear features, the number and characteristics of single AgNORs, cluster AgNORs, total AgNOR and AgNOR area/nucleus (relative area) ratio. According to their size AgNORs were classified in three categories. A one-way variance analysis and post hoc test (Scheffé) were used for statistical analysis. RESULTS: The morphometric nuclear analysis showed that benign, borderline and malignant serous ovarian tumours are statistically different (P < 0.001) according to the area and outline, the values being highest in malignant tumours and lowest in the borderline group. Digital analysis of AgNORs in benign, borderline and malignant groups showed that the total AgNOR number increases with progression of the lesion (meaning tumour malignancy) significantly (P < 0.001) between benign and malignant as well as between borderline and malignant serous ovarian tumours (P < 0.001). The progression of the lesion malignancy was accompanied by a significant (P < 0.001) progressive increase of the total and relative AgNOR area per nucleus. The AgNOR size increases from benign to malignant tumours and a statistically significant difference (P < 0.001) was observed in all three groups regarding small and large AgNORs. CONCLUSION: Combining different markers of morphometric nuclear characteristics and AgNOR values could improve differential cytodiagnosis of benign, borderline and malignant serous ovarian tumours.