ABSTRACT
Objective To propose the design of a pulsate blood pump driven by magnetic coupling and verify its feasibility. Methods The blood pump was designed based on the magnetic transmission reciprocating force model and the push-and-pull structure, and the coupling force was calculated by building the magnetic force-driven model. The prototype of the blood pump was then manufactured, on which the extracorporeal circulation simulation test was conducted to obtain the pressure and flow rate. Results Physiological saline was used as the circulation medium. When the afterload was fixed and increase the preload, the output of the blood pump would decrease, but showing no obvious linear trend. While the preload was fixed and increase the afterload, the output of the blood pump was reduced, showing a linear trend. With the driving frequency set as 75 per minute, and the preload and afterload adjusted in the range of 0.665-3.990 kPa (5-30 mmHg) and 5.320-11.970 kPa (40-90 mmHg), respectively, the output of the blood pump could reach 2.0-3.1 L/min while guaranteeing the linear relationship. Conclusions The proposed magnetic coupling-driven pulsate blood pump can basically meet the need of extracorporeal membrane pulmonary circulation, while it still needs further improvement. The research results have a valuable application prospect, especially with great significance in replacement of blood pump currently used in the extra-corporeal membrane oxygenation (ECMO) equipment in clinic.
ABSTRACT
<p><b>OBJECTIVE</b>To research many clinical data of nonunion cases and discover the reasons for low capacity of bone growth.</p><p><b>METHODS</b>From October 1999 to April 2009,the source material of 280 nonunion cases were conducted and followed up. The data of the study included 230 males and 50 females,with an average age of 39.4 years old ranging from 19 to 62 years. The fracture position was femur in 129 cases,tibia in 83 cases,humerus in 47 cases, feet radius bone in 21 cases, the ratio was 46:29.6:16.8:7.5. The survey included primary injury process,damage degree and the effect of first treatment,hospital level of first treatment,timing of surgery for the first time, the early callus growth conditions and whether there were obvious technical errors.</p><p><b>RESULTS</b>There were 129 femoral nonunion cases with complete data,121 cases derived from closed fractures, 8 cases from open fractures; 111 cases was aseptic nonunion. 90% of femoral aseptic nonunion had no obvious callus growth, 80% of first treatment performed intraday surgical internal fixation, 10% were undergone operation within three days and 90% was early surgery totally.</p><p><b>CONCLUSION</b>Low quality of bone callus growth is the main reason for current nonunion and the early surgical fixation has much to do with low quality of bone callus growth.</p>