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Travemünde, Germany

Ziaian D.,Leibniz University of Hanover | Zimmermann S.,Leibniz University of Hanover | Duembgen L.,University of Bern | Berggreen A.E.,University of Lubeck | And 3 more authors.
2013 E-Health and Bioengineering Conference, EHB 2013 | Year: 2013

Identifying and comparing different steady states is an important task for clinical decision making. Data from unequal sources, comprising diverse patient status information, have to be interpreted. In order to compare results an expressive representation is the key. In this contribution we suggest a criterion to calculate a context-sensitive value based on variance analysis and discuss its advantages and limitations referring to a clinical data example obtained during anesthesia. Different drug plasma target levels of the anesthetic propofol were preset to reach and maintain clinically desirable steady state conditions with target controlled infusion (TCI). At the same time systolic blood pressure was monitored, depth of anesthesia was recorded using the bispectral index (BIS) and propofol plasma concentrations were determined in venous blood samples. The presented analysis of variance (ANOVA) is used to quantify how accurately steady states can be monitored and compared using the three methods of measurement. © 2013 IEEE.

Engelbrecht R.,Friedrich - Alexander - University, Erlangen - Nuremberg | Lins B.,Friedrich - Alexander - University, Erlangen - Nuremberg | Zinn P.,Friedrich - Alexander - University, Erlangen - Nuremberg | Buchtal R.,Draegerwerk AG and Co. KGaA | Schmauss B.,Friedrich - Alexander - University, Erlangen - Nuremberg
Applied Physics B: Lasers and Optics | Year: 2012

Laser diode line widths and line shapes are experimentally investigated in dependence on the diode current and on back reflections from an optical system. Four distributed-feedback (DFB)-type diode lasers and two vertical-cavity surface-emitting lasers (VCSELs) have been tested within the same optical setup and using the same fitting methods. System back reflection ratios of light reflected back to the laser have been varied between -1 dB and -45 dB and were below -60 dB when all reflections were blocked. The background of this investigation is the evaluation of different laser types with respect to their suitability for sensor applications in which optical back reflections may occur, for example tunable diode-laser spectroscopy (TDLS). While DFB-type lasers showed almost pure Lorentzian line shapes and line widths of a few MHz, the tested VCSELs had a strong Gaussian contribution to the line shape, indicating stronger 1/f noise, which was also observed in the relative intensity noise of these particular lasers. System reflection ratios above -25 dB had strong effects on the line width in both DFB diode lasers and VCSELs, while some influences have been observed at even lower reflection ratios for DFB diode lasers. As much smaller reflection ratios are typically required in TDLS systems to avoid etalon-like fringes and self-mixing interference effects, we conclude that the influence on the line width is not the most important reason to minimize back reflections in practical TDLS systems or to choose one type of diode laser over the other. © 2012 Springer-Verlag.

Baether W.,Draegerwerk AG and Co. KGaA | Zimmermann S.,Leibniz University of Hanover | Gunzer F.,German University in Cairo
IEEE Sensors Journal | Year: 2012

In this paper, we use an ion mobility spectrometer with a nonradioactive ionization source that can be operated in pulsed mode, which offers the advantage of introducing delay times after the ionization. These allow the observation of substance specific signal decay times which can enhance the selectivity. The described novel principle can be used in the detection of the hazardous substance toluene 2,4-diisocyanate (TDI) in e.g., industrial areas since it offers the required sensitivity and selectivity with response times of only a few minutes. This will be shown with a focus on the TDI signal's decay characteristics regarding changes of concentration and humidity. © 2011 IEEE.

Kimberger O.,Medical University of Vienna | Saager L.,Cleveland Clinic | Egan C.,Cleveland Clinic | Sanchez I.P.,Cleveland Clinic | And 3 more authors.
Canadian Journal of Anesthesia | Year: 2013

Purpose: Perioperative hypothermia is still a common occurrence, and it can be difficult to measure a patient's core temperature accurately, especially during regional anesthesia, with placement of a laryngeal mask airway device, or postoperatively. We evaluated a new disposable double-sensor thermometer and compared the resulting temperatures with those of a distal esophageal thermometer and a bladder thermometer in patients undergoing general and regional anesthesia, respectively. Furthermore, we compared the accuracy of the thermometer between regional and general anesthesia, since forehead microcirculation might differ between the two types of anesthesia. Methods: We assessed core temperature in 36 general anesthesia patients and 20 patients having regional anesthesia for orthopedic surgery. The temperatures obtained using the double-sensor thermometer were compared with those obtained with the distal esophageal thermometer in the general anesthesia population and those obtained with the bladder thermometer in regional anesthesia patients. Results: In our general anesthesia patients, 90% (95% confidence interval [CI] 85 to 95) of all double-sensor values were within 0.5 C of esophageal temperatures. The average difference (bias) between the esophageal and double-sensor temperatures was -0.01 C. In patients undergoing regional anesthesia 89% (95% CI 80 to 97) of all double-sensor values were within 0.5 C of bladder temperatures. The average difference (bias) between the bladder and double-sensor temperatures was -0.13 C, limits of agreement were -0.65 to 0.40 C. Conclusions: In a perioperative patient population undergoing general or regional anesthesia, the accuracy of the noninvasive disposable double-sensor thermometer is comparable with that of the distal esophageal and bladder thermometers in routine clinical practice. Furthermore, the sensor performed comparably in patients undergoing regional and general anesthesia. © 2013 Canadian Anesthesiologists' Society.

Baether W.,Draegerwerk AG and Co. KGaA | Zimmermann S.,Leibniz University of Hanover | Gunzer F.,German University in Cairo
Sensors and Actuators, B: Chemical | Year: 2012

Ion mobility spectrometry (IMS) is a well-known technique applied to detect hazardous substances in ambient air. Consequently, it has been used for many years for the detection of chemical warfare agents, toxic substances or illegal drugs. The main advantages are the small size of IMS instruments and the very high sensitivity in the range of a few parts per billion. However, one major disadvantage is the fairly difficult interpretation of spectra especially when mixtures of substances are involved. Spectra recorded with a pulsed IMS, in which delay times can be inserted between ion formation and ion detection, can simplify this task due to the distinct behavior that monomer and dimer peaks exhibit with varying delay times. The discrimination between monomer and dimer signals would normally require further experimental efforts (e.g. a mass spectrometer) with disadvantages regarding the portability of the device. This paper describes how a pulsed electron gun used in a standard IMS device allows for this discrimination without compromising any of the benefits IMS devices offer. © 2012 Elsevier B.V. All rights reserved.

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