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  • Mechanical ventilation  (4)
  • magnetron sputtering  (3)
  • Albumine  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Intensive care medicine 12 (1986), S. 71-79 
    ISSN: 1432-1238
    Keywords: Cardiac output ; Flow modulation ; Mechanical ventilation ; Thermodilution method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The reliability of cardiac output estimation by thermodilution during artificial ventilation was studied in anesthetized pigs at the right side of the heart. The estimates exhibited a cyclic modulation related to the ventilation. The amplitude of the modulation was independent of the level of positive end-expiratory pressure, ventilatory pattern and volemic loading of the animals. However, a non-constant phase relation existed between the ventilatory cycle and the modulation. Single observations at a fixed moment in the ventilatory cycle are therefore not appropriate for estimation of mean cardiac output nor for studying its relative changes. The averaging of estimates spread equally over the ventilatory cycle led to a much larger reduction in the deviation of the averages from the mean cardiac output than an averaging procedure of randomly selected estimates. The accracy of estimation of mean cardiac output by two estimates equally spread in the ventilatory cycle was equal to the accuracy obtained by averaging five randomly selected estimates. Averaging four estimates, equally spread in the cycle, appeared to be the optimal procedure. For 89% of all averages an accuracy of 5% around the mean was obtained and for 99% an accuracy of ±10%.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1238
    Keywords: Cardiac output ; Mechanical ventilation ; Multiple injections ; Thermodilution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The application of the thermodilution method in conditions associated with variations in blood flow implies a misuse of the Stewart Hamilton equation. Therefore, we studied the reliability of the thermodilution method for the estimation of mean cardiac output (CO) during mechanical ventilation in patients (n=9). Variation of the injection moment in the ventilatory cycle elicited a cyclic variation of CO estimates. This variation was not the same for all patients neither in phase nor in amplitude. Therefore, no specific phase in the ventilatory cycle could be selected for an accurate estimation of mean CO. Averaging CO estimates randomly distributed in the ventilatory cycle led to an improvement of accuracy with the square root of the number of observations. The averaging of CO estimates spread equally over the ventilatory cycle led to a much better result, e.g., the variation in the average of two estimates equally spread in the ventilatory cycle was similar to the variation in the average of four random estimates. We conclude that averaging of 3 or 4 estimates spread equally over the ventilatory cycle is an adequate strategy to estimate mean cardiac output in patients reliably.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1238
    Keywords: Key words Oleic acid ; Lung injury ; Respiratory distress ; Albumine ; Bolus injections
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract   Objective: Development of a stable model of respiratory distress in pigs with oleic acid, fulfilling clinical criteria of the adult respiratory distress syndrome (ARDS). Design: Eight pigs (9.1±0.7 kg) were anesthetized with pentobarbital, paralyzed with tubocurarine and mechanically ventilated with an FIO2 of 0.6, an I:E ratio of 2:3 and a PEEP of 0.2 kPa. Oleic acid (dissolved 1:1 in 96% alcohol) was administered in a series of multiple injections of 0.1 ml until P aO2 was lower than 8 kPa. Measurements and results: Careful titration of the oleic acid injections on guidance of the P aO2 established a reproducible respiratory distress (P aO2=7.3±0.8 kPa), in which gas exchange and hemodynamic variables were stable for at least 4 h. The number of oleic acid injections (22±11, mean and SD) varied between the animals. Conclusions: With the use of multiple injections of oleic acid, a stable model of early respiratory distress in pigs can be achieved, in spite of individual differences in sensitivity. Such a stable model allows for a diversity of studies on early respiratory distress.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1238
    Keywords: Oleic acid ; Lung injury ; Respiratory distress ; Albumine ; Bolus injections
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective Development of a stable model of respiratory distress in pigs with oleic acid, fulfilling clinical criteria of the adult respiratory distress syndrome (ARDS). Design Eight pigs (9.1±0.7 kg) were anesthetized with pentobarbital, paralyzed with tubocurarine and mechanically ventilated with an $$F_{IO_2 } $$ of 0.6, an I∶E ratio of 2∶3 and a PEEP of 0.2 kPa. Oleic acid (dissolved 1∶1 in 96% alcohol) was administered in a series of multiple injections of 0.1 ml until $$P_{aO_2 } $$ was lower than 8 kPa. Measurements and results Careful titration of the oleic acid injections on guidance of the $$P_{aO_2 } $$ established a reproducible respiratory distress ( $$P_{aO_2 } $$ =7.3±0.8 kPa), in which gas exchange and hemodynamic variables were stable for at least 4 h. The number of oleic acid injections (22±11, mean and SD) varied between the animals. Conclusions With the use of multiple injections of oleic acid, a stable model of early respiratory distress in pigs can be achieved, in spite of individual differences in sensitivity. Such a stable model allows for a diversity of studies on early respiratory distress.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2013
    Keywords: Venous return ; Central venous pressure ; Inspiratory pause procedures ; Venous capacity ; Venous resistance ; Mechanical ventilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In eight mechanically ventilated, anaesthetized pigs weighing 10.3 ± 0.8 kg (mean ± SD) we studied the effect of the inflation time of the lung on the estimation of the mean systemic filling pressure (P sf) from the changes in venous return and central venous pressure during inflation of the lung. For this purpose we applied slow inflation procedures (SIP) to the lung with inflation times of 2.4, 4.8, 7.2, 9.6 and 12 s at tidal volumes (V T) of 15 and 30 ml/kg. The data were compared with the values ofP sf obtained from inspiratory pause procedures (IPPs). A linear regression between venous return and central venous pressure applied during a SIP underestimatedP sf compared with the value obtained with IPPs. An exponential fit through the values ofP sf obtained from the different SIPs predicted an inflation time of about 15 s for an estimation ofP sf that is not different from theP sf (IPP). The advantage of the SIP method is that theP sf can be determined much faster than with the method based on IPPs. However, due to the rather long inflation time needed, the method may be only applicable under circumstances where neurohumoral control mechanisms are suppressed as during intensive care and anaesthesia.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2013
    Keywords: Key words Venous return ; Central venous pressure ; Inspiratory pause procedures ; Venous capacity ; Venous resistance ; Mechanical ventilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In eight mechanically ventilated, anaesthetized pigs weighing 10.3 ± 0.8 kg (mean ± SD) we studied the effect of the inflation time of the lung on the estimation of the mean systemic filling pressure (P sf) from the changes in venous return and central venous pressure during inflation of the lung. For this purpose we applied slow inflation procedures (SIP) to the lung with inflation times of 2.4, 4.8, 7.2, 9.6 and 12 s at tidal volumes (V T) of 15 and 30 ml/kg. The data were compared with the values of P sf obtained from inspiratory pause procedures (IPPs). A linear regression between venous return and central venous pressure applied during a SIP underestimated P sf compared with the value obtained with IPPs. An exponential fit through the values of P sf obtained from the different SIPs predicted an inflation time of about 15 s for an estimation of P sf that is not different from the P sf (IPP). The advantage of the SIP method is that the P sf can be determined much faster than with the method based on IPPs. However, due to the rather long inflation time needed, the method may be only applicable under circumstances where neurohumoral control mechanisms are suppressed as during intensive care and anaesthesia.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 524-530 
    ISSN: 0021-9304
    Keywords: magnetron sputtering ; calcium phosphates ; hydroxyapatite ; carbonate apatite ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Radiofrequency magnetron sputter deposition was used to deposit Ca-P sputter coatings on titanium discs, and these coatings were implanted subcutaneously into the backs of rabbits. Half of the as-sputtered coatings were subjected to additional heat treatment for 2 h at 500°C. X-ray diffraction (XRD) demonstrated that annealing at 500°C changed the amorphous sputtered coating into an amorphous-crystalline apatite structure. Scanning electron microscopic (SEM) examination of the sputtered coatings showed excellent coverage of the substrate surface. Annealing of the 4-μm-thick coatings resulted in the appearence of small cracks. SEM demonstrated that until 4 weeks of implantation, all heat-treated coatings were present and all amorphous coatings were completely or mostly dissolved. Fourier transform infrared spectroscopy showed the formation of carbonate apatite (CO3-AP) on these specimens. Furthermore, XRD analysis showed that these CO3-AP precipitated coatings disappeared after 8 weeks of implantation. On the other hand, SEM inspection of these specimens revealed that the 4-μm heat-treated coating was still partially maintained and that small Ca-P crystals were present on the titanium substrate. On the basis of these results, we conclude that apparently 0.1 μm heat-treated Ca-P sputter coating is of sufficient thicknesses to stimulate carbonate apatite deposition under in vivo conditions. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 524-530, 1998.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 40 (1998), S. 464-474 
    ISSN: 0021-9304
    Keywords: calcium phosphate coatings ; magnetron sputtering ; osteoblast ; in vitro ; bone ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In previous studies we developed a RF magnetron sputter technique for the production of thin Ca-P coatings. With this technique coatings can be produced that vary in Ca/P ratio as well as in structural appearance. The aim of this investigation was to obtain more understanding of the biological behavior of these coatings by way of in vitro experiments. The effect of noncoated titanium (Ti) and three different Ca-P-sputtered surfaces on the proliferation and differentiation (morphology and matrix production) of osteoblast-like cells was studied. Proliferation was determined using counting procedures; morphology was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fluorescent markers and energy-dispersive X-ray microanalysis (EDX) were used to obtain quantitative and compositional information about the resultant calcified extracellular matrix (ECM). Results demonstrated that proliferation of the osteoblast-like cells was significantly (p 〈 0.05) higher on noncoated than on Ca-P-coated samples. On the other hand, more mineralized ECM was formed on the coated surfaces. In addition, TEM confirmed that the cells on the coated substrates were surrounded by ECM with collagen fibers embedded in crystallized, needle-shaped structures. On the basis of these findings, we concluded that: (1) the investigated Ca-P sputter coatings possess the capacity to activate the differentiation and expression of osteogenic cells, and (2) bone formation proceeds faster on Ca-P surfaces than on Ti substrates. Further, this bone-inductive effect appeared to be dependent on the Ca-P ratio of the deposited coatings. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 464-474, 1998.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 43 (1998), S. 270-276 
    ISSN: 0021-9304
    Keywords: magnetron sputtering ; calcium phosphates ; subperiosteal ; oesteogenesis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The aim of this study was to obtain more information about the initial biological events around RF magnetron sputtered calcium phosphate (Ca-P) coatings. Therefore, uncoated and coated disks were inserted subperiosteal into the tibia of a goat. The coatings were deposited on commercially pure titanium. The thickness of the coating was 0.1 or 2.0 μm. All the as-sputtered coatings were subjected to an additional heat treatment for 2 h at 500°C. After 1 and 3 weeks of implantation the experimental disks were retrieved and prepared for histological and physicochemical analysis. The histological results demonstrated that the periosteum covered the specimens after both implantation periods. In between the periosteum and implant an acellular layer and a collagen matrix was observed. Energy dispersive spectrometry revealed that the acellular layer consisted of C, Ca, and P ions for the 0.1 μm thick Ca-P coatings. The 2 μm thick Ca-P coatings also showed the presence of sulfate ions in this layer. Only organic material was found on the titanium disks. Further, SEM showed that even after 3-week implantation, a substantial thickness of both coatings was still maintained. Thin film X-ray diffraction demonstrated that after both implantation periods, the CaP-0.1 coating was still present. FTIR of the retrieved specimens demonstrated on the coated disks the formation of additional carbonate apatite (CO3-AP) associated with an organic phase (NH2 groups). On basis of these findings we conclude that our experimental approach is very suitable for the investigation of the healing process around Ca-P coatings. Further, we again demonstrated that the initial interfacial response to Ca-P materials differs from titanium. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 43: 270-276, 1998
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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