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A4136
October 16, 2018
10/16/2018 10:30:00 AM - 10/16/2018 12:30:00 PM
Room North, Hall D, Area C
Relation Between the Loaded Pressure and the Flow Rate of Various Infusion Lines in High Pressurized Condition
Hirotsugu Miyoshi, M.D.,Ph.D., Ryuji Nakamura, M.D.,Ph.D., Toshimichi Yasuda, M.D.,Ph.D., Hiroshi Hamada, M.D.,Ph.D., Masashi Kawamoto, M.D.,Ph.D.
Hiroshima University Hospital, Hiroshima, Japan
Disclosures: H. Miyoshi: None. R. Nakamura: None. T. Yasuda: None. H. Hamada: None. M. Kawamoto: None.
Background and Goal of Study It has been reported that the relation between the loaded pressure on the catheter and the infusion flow rate is nonlinear. [Ref.1] However, they did not consider the relation of the entire infusion line. Furthermore, their research carried out in the low pressurized condition. Since flow rate of infusion line is influenced by not only catheter but also the other parts of infusion line, we should focus on the characteristics of entire system, when considering in clinical use. Thus, we investigated the relation between the loaded pressure and the flow rate of entire system that was installed various catheters in high pressurized condition. Materials and Methods Experiment 1. An 18, 20, 22 or 24 G catheter (BD Insyte™ Autoguard™) was connected to the end of an infusion line containing a warming coil and needle free stopcocks, and the flow rate of pressurized saline was measured. We pressurized the saline in stages using a compressor, at the upstream of the infusion line (pressure in 10 steps from 50 to 1050 mmHg). Then, we measured the pressure at the upstream of the line (P1: the loaded pressure of the entire system) and the pressure just before the catheter (P2: the loaded pressure just before the catheter). The flow rate (gram/minute) at each pressure of each size catheter was measured. We approximated the relation of the loaded pressure and the flow rate as the following formula and calculated the best approximation by Microsoft Excel. Q = a1 × P1 b1, and Q = a2 × P2 b2, where Q is a flow rate, a1 and a2 are the coefficients in the best approximation, b1 and b2 are the degrees of the entire system and the installed catheter in the best approximation. Experiment 2. The experiment was carried out in the same way using 40% glycerin, which mimicked the viscosity of blood. Results and Discussion The values of R2 were over 0.98 in all settings. Result of the experiment 1. The b1 values for the 18, 20, 22, and 24G catheter were 0.72, 0.72, 0.70, and 0.68, respectively, while those for b2 were 0.58, 0.60, 0.62, and 0.62, respectively. Since the values of b1 is closer to 1.00 than the values of b2, the relation between loaded pressure and flow rate was more linear in the entire system than that in just before the catheter. (Figure1,2) Result of the experiment 2. The b1 values for the 18, 20, 22, and 24G catheter were 0.86, 0.83, 0.83, and 0.80, respectively, while those for b2 were 0.70, 0.71, 0.73, and 0.73, respectively. Same as experiment 1, the relation between loaded pressure and flow rate was more linear in the entire system than that in just before the catheter. Conclusion Although the relation between the loaded pressure just before the catheter and infusion flow rate was nonlinear, the relation between the loaded pressure in the entire infusion line and flow rate was close to linear. Reference 1. Anesth Analg 2009; 108: 1198-202.
Figure 1
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