International journal of clinical monitoring and computing
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Int J Clin Monit Comput · Jan 1991
Monitoring of coagulation status using thrombelastography during paediatric open heart surgery.
Thrombelastography (TEG) has proved useful in identifying coagulopathies (via assessment of clot elasticity properties) during hepatic surgery, but its role in cardiac surgery has as yet not been defined. Twenty-two children [11M, 11F, mean age (range) 4.9 (0.1-16) years] undergoing open heart surgery were investigated [1] preoperatively, [2] 15 min post protamine, [3] 2 h and [4] 24 h postoperatively using TEG. Comparisons were made between pre- and postoperative measurements and haematological indices. ⋯ TEG predicted with 100% (8/8) accuracy increased post-operative bleeding. The specificity of TEG prediction of future bleeding was 73% [8/11]. Alterations in TEG parameters merit further evaluation as markers of postoperative haemorrhage.
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In the control of the circulation it is suggested there is merit in describing states which are the object of each therapy. Considering the determinants of venous return rather than those of cardiac output, we suggest that the mean systemic filling pressure is a parsimonious description of the volume state. A method is described of deriving a mean systemic filling pressure analogue based on stopping the flow in a notional regional systemic circulation. ⋯ The systemic vascular resistance is a conventional measure of the state of arteriolar resistance. We suggest that the ratio (PM - PRA)/PM (where PRA is the right atrial pressure) is a global measure of the effect of cardioactive drugs. Studies are reported in which the mean blood pressure, right atrial pressure and cardiac output are simultaneously controlled within desired tolerances using state based control.
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Most anesthesiologists, relying upon sales presentations from salesmen from oximeter manufacturers, believe that if an oximeter produces a steady signal with a good pulse amplitude, the numbers are always believable in the absence of interference from external light sources or from intravenous dyes. Here I report a case in which an oximeter appeared to be working properly yet displayed values which were falsely low. Trust in the oximeter resulted in delayed identification of the problem.
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Int J Clin Monit Comput · Apr 1989
EEG and SEMG monitoring during induction and maintenance of anesthesia with propofol.
Propofol has been used as IV induction (2 mg/kg) and maintenance agent (150 micrograms/kg/min and 100 micrograms/kg/min after 30 min), combined with N2O/O2 in 16 premedicated (atropine 0.5 mg, Thalamonal 2 ml IM) and mechanically ventilated patients, having ear surgery or arthroscopy. Cranial biopotentials were analysed by 2 different techniques: 1. The Anesthesia and Brain Activity Monitor (ABM Datex) providing the zero crossing frequency (ZXF) as a value for the mean frequency of the EEG signal during a considered time interval, the mean integrated voltage (MIV) as a mean value of the amplitude of the same EEG signal and the spontaneous electromyography of the frontal muscle (SEMG). 2. ⋯ A correlation was looked for between the EEG changes and the propofol blood concentrations. The higher the propofol blood concentrations, the more pronounced the low frequency bands. The appearance of beta waves or a ZXF greater than 10 Hz indicates pending arrousal.