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  • 1
    Electronic Resource
    Electronic Resource
    Effects of thiopentone, etomidate and propofol on beat-to-beat cardiovascular signals in man (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 48 (1993), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Analysis of beat-to-beat fluctuations of heart rate and blood pressure is a promising new approach to the clinical diagnosis and management of alterations in cardiovascular regulation. We investigated the effects of three induction agents on beat-to-beat heart rate and blood pressure fluctuations in man. Beat-to-beat fluctuations were analysed by spectral analysis. Two spectral areas are of main interest. One area is centred on the respiratory frequency and shifts with changes in respiratory rate (High Frequency area). These high frequency flucuations in heart rate are caused by respiratory-induced blood pressure fluctuations, mediated by the vagus nerve through the baroreflex mechanism. Variability in the Low Frequency area, which occurs between 0.06 and 0.12 Hz is considered to be related to haemodynamic fluctuations due to the sympathetic baroreflex control loop of vasomotor activity and heart rate. Results from our study indicate that thiopentone, etomidate and propofol show considerable differences in their effects on beat-to-beat variability of heart rate and blood pressure. These differences can be explained by their specific effects on the cardiovascular system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2044.1993.tb07412.x
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of P50 and oxygen transport in patients after cardiac surgery (1996)
    Springer
    Intensive care medicine 22 (1996), S. 781-789 
    Details
    ISSN: 1432-1238
    Keywords: Key words P50 ; Blood transfusion ; Oxygen transport ; Oxygen availability ; Cardiac surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: To determine whether standard P50 after cardiac surgery decreases and whether decreased P50 is related to the transfusion of red blood cells (RBCs), acid-base changes, body temperature, oxygen parameters and/or duration of cardiopulmonary bypass (CPB). Design: Pilot study in cardiac surgery patients. Setting: University hospital. Patients: 12 consecutive elective cardiac surgery patients. Interventions: Blood was taken before surgery, after CPB and in the intensive care unit until 18 h post-operatively. Cardiac output and oxygen consumption were measured. Buffy coat-poor RBCs were transfused, anticoagulated with citrate-phosphate-dextrose buffer and stored in saline-adenine-glucose-mannitol at 4°C, when haemoglobin was 〈5.6 mmol·l–1. Measurements and results: Standard P50 was calculated from measured partial pressure of oxygen and of carbon dioxide, pH and oxygen saturation in mixed venous blood (SvO2) using the Severinghaus formula. Median length of RBC storage was 25 days. Standard P50 after surgery was significantly lower than baseline value (p=0.0001). The number of RBC units transfused and duration of CPB were conjointly associated with P50 (R 2=0.72). Patients who received more RBCs consumed more oxygen. Conclusion: Cardiac surgery patients receiving more RBC units have lower standard P50 and consume more oxygen. P50 decreased more when the CPB took longer. Because a decrease in P50 implies a low ratio of mixed venous oxygen tension (PvO2) to SvO2, a shift in P50 should be taken into account when using SvO2 as a measure of global oxygen availability. When a direct measurement of SvO2 is not available, PvO2 should be used instead of calculated SvO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01709521
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of P50 and oxygen transport in patients after cardiac surgery (1996)
    Springer
    Intensive care medicine 22 (1996), S. 781-789 
    Details
    ISSN: 1432-1238
    Keywords: P50 ; Blood transfusion ; Oxygen transport ; Oxygen availability ; Cardiac surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective To determine whether standard P50 after cardiac surgery decreases and whether decreased P50 is related to the transfusion of red blood cells (RBCs), acid-base changes, body temperature, oxygen parameters and/or duration of cardiopulmonary bypass (CPB). Design Pilot study in cardiac surgery patients. Setting University hospital. Patients 12 consecutive elective cardiac surgery patients. Interventions Blood was taken before surgery, after CPB and in the intensive care unit until 18 h post-operatively. Cardiac output and oxygen consumption were measured. Buffy coat-poor RBCs were transfused, anticoagulated with citratephosphate-dextrose buffer and stored in saline-adenine-glucose-mannitol at 4°C, when haemoglobin was 〈5.6 mmol·l−1. Measurements and results Standard P50 was calculated from measured partial pressure of oxygen and of carbon dioxide, pH and oxygen saturation in mixed venous blood (SvO2) using the Severinghaus formula. Median length of RBC storage was 25 days. Standard P50 after surgery was significantly lower than baseline value (p=0.0001). The number of RBC units transfused and duration of CPB were conjointly associated with P50 (R 2=0.72). Patients who received more RBCs consumed more oxygen. Conclusion Cardiac surgery patients receiving more RBC units have lower standard P50 and consume more oxygen. P50 decreased more when the CPB took longer. Because a decrease in P50 implies a low ratio of mixed venous oxygen tension (PvO2) to SvO2, a shift in P50 should be taken into account when using SvO2 as a measure of global oxygen availability. When a direct measurement of SvO2 is not available, PvO2 should be used instead of calculated SvO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01709521
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Oxygen consumption after cardiopulmonary bypass — implications o of different measuring methods (1993)
    Springer
    Intensive care medicine 19 (1993), S. 105-110 
    Details
    ISSN: 1432-1238
    Keywords: Oxygen consumption ; Cardiopulmonary bypass ; Pulmonary gas exchange ; Energy metabolism ; Physiological monitoring ; Intra-pulmonary oxygen consumption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective To determine whether intra-pulmonary oxygen consumption or whole body oxygen consumption is the main determinant of the hypermetabolic response after cardiopulmonary bypass. Secondly, which method of measuring oxygen consumption best quantifies this hyperdynamic response. Design We measured oxygen consumption by analysing respiratory gas (VO2-gas), carbon dioxide excretion (VCO2), and respiratory exchange ratio (RER = VCO2/VO2), and calculated oxygen consumption using the Fick-method (VO2-Fick) and intra-pulmonary oxygen consumption (VO2-gas — VO2-Fick) in patients at fixed times before and after elective cardiac surgery. Next, comparisons were made between methods and also between measurements at different times before and after bypass. Setting University hospital Patients 10 elective cardiac surgical patients Interventions None Measurements and results VO2-gas, VCO2 and RER were measured with an open circuit indirect calorimeter VO2-Fick was calculated: VO2-Fick=cardiac indexx(arterial — mixed venous oxygen content). Intrapulmonary oxygen consumption was calculated as the difference between VO2-gas and VO2-Fick. Both VO2-gas and VO2-Fick were about 20% higher after bypass than after induction of anaesthesia. Absolute values of VO2-gas were about 30% higher than VO2-Fick. Intra-pulmonary oxygen consumption accounted for 32% of whole body oxygen consumption after induction of anaesthesia and did not increase after bypass. Conclusion Whole body oxygen consumption and not intra-pulmonary oxygen consumption is the main determinant of the hypermetabolic response after bypass. Increased intra-pulmonary oxygen consumption is not related to bypass. VO2-gas best quantifies this hypermetabolic response directly after bypass, and not VO2-Fick, VCO2 or intra-pulmonary oxygen consumption, since VO2-Fick excludes intra-pulmonary oxygen consumption and VCO2 does not reflect metabolism directly after bypass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01708371
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    Paper (German National Licenses)
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