Effects of bubble size differences on the bubble-trapping performance of arterial line filters
Atsushi Nakamura (Department of Clinical Engineering, Faculty of Health Sciences,Kyorin University), Masahiro Kikuta
Abstract
Microbubbles inside a cardiopulmonary bypass circuit are captured by a venous reservoir orby the artificial lung, and ultimately, an arterial line (ALF) prevents gaseous micro-emboli(GME) from getting injected into the patient’s body. In our study using ALFs with pore sizesof 40μm (PS40) and 20μm (PS20), bubbles with a mean bubble diameter of 50μm, 100μm, and 180μm were injected into the ALF. Arterial line filter GME removal was examinedusing different bubble sizes.
In the bubble group with various bubble sizes, the number of bubbles and the rate of bubble
removal were determined for 50 μ m bubbles (PS40=44.5 ± 0.7%, PS20=56.1 ± 0.4%,P>0.001), 100μm bubbles (PS40=13.7±1.9%, PS20=9.9±3.8%, P=0.205), and 180μmbubbles (PS40=−7.0±1.5%, PS20=−29.3±1.8%, P＜0.001). Air shrinkage and bubble
removal rates were significantly higher with PS20.
The bubble’s internal pressure becomes lower as the bubble size is larger, which suggeststhat air bubbles can easily change shape and disrupt. This suggests that GME removal
capability increases when all microbubbles that flow into the ALF are maintained at a diameterof 40-50μm or less.
Key words
gaseous microemboli (GME), microbubbles, bubble trap performance, arterial line filter

Postoperative cognitive dysfunction following cardiac surgery
Kazuyuki Nagaya (The Sakakibara Heart Institute of Okayama), Kosuke Nakajima,
Arudo Hiraoka, Masahisa Arimichi, Tomoya Oshita, Ryosuke Muraki, Yoshitaka Naito,
Manami Himeno, Taichi Sakaguchi
Abstract[Background] Various causes of postoperative cognitive dysfunction (POCD) following
cardiac surgery have been speculated, including a previous report that found use of a heartlung machine to be a causative factor.
[Methods] We investigated 160 consecutive patients who underwent a heart valve operation
with a cardiopulmonary bypass, and received 4 different types of pre- and postoperative
recognition function tests. Those who showed a greater than 20％ reduction in postoperative
test values or experienced difficulty with the assessments following surgery were judged to bePOCD. Factors related to POCD occurrence were then evaluated using multivariate analysis.
[Results] POCD occurred in 49 cases (30.6%). Comparisons between the onset and nononset groups revealed that patients with onset were significantly older, while many of those
had a medical history of cognitive impairment and blood symptoms, as well as higher HbA1cvalues. The onset group also had a significantly shorter rewarming time during
cardiopulmonary bypass, and significantly lower perfusion index (PI), hemoglobin, andoxygen delivery (DO2i) values during rewarming. During the postoperative course, the onset
group had a significantly higher creatinine value, greater rate of increase in postoperative
serum creatinine, longer intubation time, and longer length of ICU or hospital stay.
Multivariate analysis showed age (cut-off value 72 years, AUC 0.71, OR 6.09, CI 2.40-15.5;
P=0.0021) and DO2i during rewarming at 35℃ (cut-off value 276ml/min/m2, AUC 0.79,
OR 9.28, CI 4.22-20.4; P＜0.0001) as independent risk factors for POCD occurrence.
[Discussion] POCD following cardiac surgery results not only in a decline of cognitive
capacity, but also has a negative influence on the postoperative course. Notably, for effective
cardiopulmonary bypass management in elderly patients, maintaining an adequate DO2i
value during rewarming is important.
[Conclusion] Both age and DO2i during the rewarming period following a cardiopulmonary
bypass were found to be factors related to POCD occurrence in cardiac surgery patients.
Key wordspostoperative cognitive dysfunction (POCD), age, recognition function test, DO2i

A survey of the methods for efficiently training patients and their caregivers on how tohandle implantable ventricular assist devices
Koichi Kashiwa (Department of Medical Engineering, The University of Tokyo
Hospital), Hideo Kurosawa, Mai Takahashi, Sayaka Koga, Haruka Asakura, Saori Fujiya,Kazuki Fujishiro, Katsushi Tanita, Hitoshi Kubo, Yukie Kagami, Mariko Nemoto, MiyokoEndo, Rie Amao, Osamu Kinoshita, Mitsutoshi Kimura, Kent Doi, Minoru Ono
Abstract
This survey targeted 128 patients with approved implantable ventricular assist devices(iVADs) in Japan implanted from April 2011 to September 2017, and 330 caregivers that weretrained on the handling of iVADs. We looked into the outcomes of tests for handling theirwearing iVADs.
We then studied the relationship between the results of device handling tests and the trail
making test-B (TMT-B) performed for patients; 3 and/or 6 months after implanting iVADs.
The data was analyzed by Fisher’s exact test, with p＜0.05 considered statistically significant.
The number (rate) of patients who required re-testing for competency more than 3 times wasfor EVAHEART®, DuraHeart®, HeartMateⅡ®, Jarvik2000®; 0, 0, 4, 3 (0, 0, 8.7, 10.0%),respectively. Also, the rate of caregivers who required re-testing for competency more than 3time was 0, 0, 5.8, 11.3％, respectively. The relationship between the results of the device
handling test and the trail making test-B (TMT-B) was considered statistically significant(p=0.002), the sensitivity and specificity were 29.1, 95.5％, respectively. These results may
suggest the possibility that training on the handling of iVADs can be efficiently conducted inreference to the outcome of TMT-B. However, the frequency of the device test required tends
to depend on the types of iVADs that the patient receives. Our previous study showed that
there was an association between the types of devices and the incidence rate of mistakes.
Therefore, we strongly feel the importance of adapting fool proof and/or fault tolerant indesigning the devices, thereby improving the usability for efficient training on the handlingof iVADs.
Key words
ventricular assist devices, handling training, trail making Test-B, usability

Study for the quantification of the roller pump occlusion on the cardio-pulmonary bypass―Definition factors of the roller pump occlusion on stable the roller pump operation−
Shota Kato, (Clinical Engineering Faculty of Health Science, Gunma Paz University
Research Associate School), Yoshimasa Kusama, Kaoru Abe, Takashi Shibamoto
Abstract
In our country, a centrifugal pump is chosen by the open-heart surgery that have gave top
priority to safety and bio-compatibility. However, in the foreign countries, the open-heart
surgery using the roller pump increases in consideration of operability and economy. The
roller pump occlusion paid attention to the long-time operation causing axis displacement;
Our study carried out that perfusion temperature executed the technology as a rule factor ofthe occlusion.
To evaluate the manifestation of the circumference of the occlusion, we used three kinds ofdifferent rollers diameter and measured perfusion temperature(Pt)and the electrical resistivity(Rz: resistance sigma), a pressure degree of the occlusion. Based on JIS-T1603, we observed
the changed to kinds of the three pumps with degree of the occlusion which we were setting inthe same condition as change of the occlusion by the progress at time. Pt and Rz repeated updown motion in three pumps every 30-60 minutes. In addition, the occlusion extended theinterval in progress at time. The pressure level of the sensor rose every 30 minutes andbecame unmeasurable afterwards.
This phenomenon affects is that perfusion temperature changes influence the blood
viscosity and, we suppose that it influenced a rise in para-blood temperature and it appearedin pressure change and Rz of the occlusion. Therefore, control of the Pt leads to theappropriate control of the roller pump and thinks with an indispensable element though wecarry out physiological extracorporeal.
Key words
occlusion, perfusion temperature, electrical resistivity (resistance sigma)