![]() Ordinary "flushing" calls for harsh solvents (kerosene, paint thinner or Stoddard sovents,etc) are extremely hard on engine seals such as crank/cam seals, valve guide seals,etc. Dynamic response of a neonatal catheter-manometer system in situ.Naaah! I wouldn't "flush" the engine with anything but the following (if you really want to "flush" it, which I pretty much doubt the need for that): AutoRx, or HDEO/XD-3 oils. Van Langen H, Brienesse P, Kopinga K, Wijn P. The fast flush test measures the dynamic response of the entire blood pressure monitoring system. ![]() Kleinman B, Powell S, Kumar P, Gardner RM. Frequency response testing in catheter-transducer systems. A method of determining the undamped natural frequency and the damping in overdamped and slightly underdamped systems of one degree of freedom by means of a square-wave impact. Catheter-flush system for continuous monitoring of central arterial pulse waveform. Gardner RM, Warner HR, Toronto AF, Gaisford WD. Physiologic recording by modern instruments with particular reference to pressure recording. Direct blood pressure measurement - dynamic response requirements. Specifically, small amounts of air in fluid-filled invasive blood pressure monitoring systems cause a slightly worse dynamic response as measured by FF testing versus the laboratory gold standard - the SW test. However, under certain conditions - air, R.O.S.E device - dynamic response as measured by FF testing was not equivalent to dynamic response as measured by the gold standard - the SW test. For the characterization of dynamic response of invasive blood pressure monitoring systems, the FF test and SW test yield identical results. The R.O.S.E device created marked qualitative differences, although exact fn and ζ could not be quantified. Damping was also always greater by FF testing than by SW testing in systems with air for all catheter sizes and extension tubing lengths (p < 0.05). However, in systems containing air, fn by FF testing was always less than fn by SW testing for all catheter sizes and extension tubing lengths (p < 0.05). There was no significant difference between fn and ζ as calculated from the step response generated from the FF test versus fn and ζ as calculated from the square wave (SW) test in systems without air. These procedures were repeated after 0.05 cc of air was introduced in the transducer and repeated again in a system containing a damping device (R.O.S.E., Resonant OverShoot Eliminator, Viggo-Spectramed, Oxnard, CA). Square waves so generated were recorded as described above and natural frequency and damping coefficients calculated. Next, square waves were generated by closing the port that was open to atmosphere and attaching a signal generator to a pressure generator. Subsequent step response signals from the FF tests were then recorded from which natural frequency (fn) and damping coefficient (ζ) were calculated. ![]() With the other port of the pressure generator open to atmosphere, FF tests were performed by activating the flush device of the transducer. The catheter tip was inserted into one port of a pressure generator. The system was attached to a pressurized saline flush. An arterial recording system was assembled in the standard fashion by attaching a catheter to arterial pressure tubing, which was attached to a transducer (TXX-R, Ohmeda, formerly Viggo-Spectramed, Oxnard, CA) whose signal was recorded by a strip chart recorder (Gould 2400, Rolling Meadows, IL). We studied three different 5.1 cm catheter sizes (16G, 18G, 20G Becton Dickinson, Sandy, UT) attached to three different lengths of arterial pressure tubing (36 in, 91.4 cm 72 in, 182.9 cm 108 in, 274.3 cm). Results from these two test methods have been assumed equal but have not been empirically confirmed. Fast flush (FF) testing is the clinical test of choice. ![]() Generation of a square wave (SW) at the catheter tip is the engineering and in vitro laboratory gold standard. The accurate recording of intraarterial pressure depends upon an appropriate dynamic response of the monitoring system. ![]()
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