Naoki Momose

Quantitative evaluation of hand cranking a roller pump in a crisis management drill

The heart-lung machines for open-heart surgery have improved over the past 50 years; they rarely break down and are almost always equipped with backup batteries. The hand-cranking procedure only becomes necessary when a pump breaks down during perfusion or after the batteries have run out. In this study, the performance of hand cranking a roller pump was quantitatively assessed by an objective method using the ECCSIM-Lite educational simulator system. A roller pump connected to an extracorporeal circuit with an oxygenator and with gravity venous drainage was used. A flow sensor unit consisting of electromagnetic sensors was used to measure arterial and venous flow rates, and a built-in pressure sensor was used to measure the water level in the reservoir. A preliminary study of continuous cranking by a team of six people was conducted as a surprise drill. This system was then used at a perfusion seminar. At the seminar, 1-min hand-cranking drills were conducted by volunteers according to a prepared scenario. The data were calculated on site and trend graphs of individual performances were given to the participants as a handout. Preliminary studies showed that each person’s performance was different. Results from 1-min drills showed that good performance was not related to the number of clinical cases experienced, years of practice, or experience in hand cranking. Hand cranking to maintain the target flow rate could be achieved without practice; however, manipulating the venous return clamp requires practice. While the necessity of performing hand cranking during perfusion due to pump failure is rare, we believe that it is beneficial for perfusionists and patients to include hand-cranking practice in periodic extracorporeal circulation crisis management drills because a drill allows perfusionists to mentally rehearse the procedures should such a crisis occur.

Incident-simulating device with wireless control for extracorporeal circulation crisis management drills.

Incidents during extracorporeal circulation (ECC) may lead to serious consequences, and troubleshooting exercises are becoming more important. We developed an incident-simulation device operated by remote control for ECC crisis management drills, and evaluated its efficacy at a seminar for perfusionists. This compact device consists of a transmitter and a receiving system and is run by dry batteries without a personal computer. A 4-channel radio-control system is used as the transmitter, and four servomotors placed in a box as the receiving system. To simulate occlusion of 3/8” arterial and venous lines, two servomotors with a rod rotate and the rod compresses the tube. The tilt angle of the stick and the servomotor rotation are in proportion, so that the degree of occlusion is controlled. As a result, the tube lumen becomes “stenotic” and then occluded, depending on the rotation. To cut off the power, the other two servomotors, with a relay system, work as a breaker. When the rod of the servomotor rotates, a micro-switch is turned off. The present device is able to increase perfusion pressure quickly and to simulate inadequate venous drainage quietly. At a seminar for perfusionists, an instructor manipulated the transmitter to create incidents and the participants handled the events effectively. In conclusion, incidents created by this device were perceived as similar to real ECC crises and this device may be useful and educationally effective when used in crisis management drills for perfusionists and trainees.

Use of an extracorporeal circulation perfusion simulator: evaluation of its accuracy and repeatability

Medical simulators have mainly been used as educational tools. They have been used to train technicians and to educate potential users about safety. We combined software for hybrid-type extracorporeal circulation simulation (ECCSIM) with a CPB-Workshop console. We evaluated the performance of ECCSIM, including its accuracy and repeatability, during simulated ECC. We performed a detailed evaluation of the synchronization of the software with the console and the function of the built-in valves. An S-III heart–lung machine was used for the open circuit. It included a venous reservoir, an oxygenator (RX-25), and an arterial filter. The tubes for venous drainage and the arterial line were connected directly to the ports of the console. The ECCSIM recorded the liquid level of the reservoir continuously. The valve in the console controlled the pressure load of the arterial line. The software made any adjustments necessary to both arterial pressure load and the venous drainage flow volume. No external flowmeters were necessary during simulation. We found the CPB-Workshop to be convenient, reliable, and sufficiently exact. It can be used to validate procedures by monitoring the controls and responses by using a combination of qualitative measures.

Certified perfusionists in Japan

This year, the 20th qualifying examination on the extracorporeal circulation technique for a certified perfusionist was conducted. A total of 569 certified perfusionists had qualified in Japan up to November 2006.

Development of a new control device for stabilizing blood level in reservoir during extracorporeal circulation

We developed a simple device that stabilizes the blood level in the reservoir of the extracorporeal circulation open circuit system by measuring the hydrostatic pressure of the reservoir to control the flow rate of the arterial pump. When the flow rate of the venous return decreases, the rotation speed of the arterial pump is automatically slowed down. Consequently, the blood level in the reservoir is stabilized quickly between two arbitrarily set levels and never falls below the pre-set low level. We conducted a basic experiment to verify the operation of the device, using a mock circuit with water. Commercially available pumps and reservoir were used without modification. The results confirmed that the control method effectively regulates the reservoir liquid level and is highly reliable. The device possibly also functions as a safety device.

Extracorporeal circulation technical training DVD volume 1: basic operation and troubleshooting scenarios

The Committee of Education of the Japanese Society for Artifi cial Organs believes that the teaching of safety with respect to extracorporeal circulation technique is important. Consequently, a DVD titled “Measures to Resolve Incidents During Extracorporeal Circulation” (Fig. 1) was produced. It is the fi rst educational DVD on extracorporeal circulation (ECC) produced in Japan by the Japanese Society for Artifi cial Organs with cooperation from The Japanese Society of Extra-Corporeal Technology in Medicine (JaSECT). The production aimed at ensuring and improving safety during ECC. In this DVD, the maneuvers employed in crisis management drills are presented with narration and dialogue in Japanese. The learning objective was to promote appropriate action for specifi c situations when a problem related to ECC occurs. Additionally, the usefulness of safety devices, the proper location for pressure measurement, the locations for fi xing sensors, and other technical aspects are presented. This DVD helps perfusionists to confi rm the installation of safety devices and the location where the pressure of the oxygenator can be appropriately measured. When there is more than one solution to a problem, ideally such a DVD should cover all possible approaches to problem solving. However, we have chosen several incidents and only one solution for each is shown; the reason for this is that choices of solution change by the situation. This DVD was produced based on the information available in Japan concerning safety measures of extracorporeal technology in 2006, and we believe that this information is still applicable at the current time. An English translation of the DVD scenarios is given below with the authors’ comJ Artif Organs (2009) 12:278–282

Distribution of certified perfusionists in core training institutions accredited by the Japanese Board of Cardiovascular Surgery in Japan

In 2008, the 22nd qualifying examination for certified perfusionist was conducted on extracorporeal circulation techniques. A total of 647 people had passed the qualifying examination and become certified perfusionists by the end of 2008.

Clinical application of rotation control equipment of roller pump using newly developed circuit internal pressure.

我々は,回路内圧の変化に従い,ローラーポンプの回転数を制御する装置を開発した。本装置の特徴は,ローラーポンプ本体は改造しないこと,制御を開始する回路内圧の点(S)と制御を行う圧力の幅(W)を設定すること,Wの中で圧力の値に比例した制御を行うこと,陰圧に対しても使用できることである。本装置を取り付けたローラーポンプの流量― 圧力特性は,回路内圧がSに達するまではローラーポンプ特性を維持し,回路内圧がSに達すると,流量が圧力と逆比例し変化する遠心ポンプと同様な特性を示す。本装置を臨床に応用した結果,送血回路の折れ曲がりや送血カニューレの先当たりに対し,危険な回路内圧の発生を防ぐことができた。ポンプ脱血時には脱血不良に対して過度の陰圧の発生を防ぐことができた。更に臓器灌流においても,一定の圧力を維持しながら灌流させることができた。

New heart-lung machine support system.

我々が1989年に開発した体外循環を支援する人工心肺支援システムを基本として,新しい人工心肺支援システムを,NECメディカルシステムズ社と共同で開発した。新しい人工心肺支援システムは人工心肺の準備から体外循環,報告書の作成や体外循環データの利用まで一貫した支援が行える。体外循環中は,体外循環に関するイベントを入力することで,体外循環の状況をコンピュータが認識して最適なデータの監視や支援が行えることや,テンキーだけでほとんどのコンピュータ操作が行えること,音声出力などを活用していることが特徴である。新しい人工心肺支援システムを,1997年4月より410例の体外循環に使用した。この結果,画面を凝視しなくてもコンピュータ操作が容易に行え,体外循環中の血行動態や温度の異常を素早く察知することができた。更に,新しい人工心肺支援システムは,従来のシステムに比べて操作性,処理速度,汎用性,データの有効利用などにおいて高い性能を示した

Extracorporeal circulation technology by semi-enclosure circuit. Clinical application of perfect closed type artificial heart-lung machine circuit.

循環血液流量(送血流量)と循環血液量を独立して管理できる完全閉鎖回路の臨床応用に向けて,体外循環の主な血流が貯血槽を通らない人工心肺回路(半閉鎖回路)を作製した。本回路の特徴は,従来の人工心肺回路のように主な血液の流れの中に貯血槽を置かないことと,簡単に完全閉鎖回路とすることができることである。本回路には,脱血回路に混入した気泡を貯血槽で除去できない大きな問題点がある。対策として人工肺およびエアトラップにより気泡除去を行うこととした。in vitro testにおいて混入させた気泡は,全て人工肺で除去できることが解った。本回路を92例に臨床応用し,安全に体外循環を行うことができた。今後,完全閉鎖回路の臨床応用が課題である。