Risk factors for intraoperative saddle nose deformity in septoplasty patients.

INTRODUCTION: Septoplasty is one of the most common otolaryngologic procedures. Previous studies have reported that the overall rate of significant change in cosmetic appearance of the nose after septoplasty ranged from 0.4 to 3.4%, and saddle nose was the most commonly cited deformity. In this study, we evaluated the risk factors for intraoperative saddle nose in a group of septoplasty patients. METHODS: This case-control study (1:2 case:control) was conducted based on retrospective chart review. Intraoperative saddle nose was observed in 108 (5.1%) of 2106 patients who underwent septoplasty in our center between January 2008 and December 2017. The control group consisted of 216 randomly selected, hospital-matched septoplasty patients who had no intraoperative saddle nose deformity in the same period. The demographic data, preoperative endoscopic findings, and surgical procedures of the two groups were analyzed to identify possible risk factors of intraoperative saddle nose deformity. RESULTS: The mean ages of the two groups were 34.8 years (saddle group) and 33.2 years (control group). In multivariate logistic regression analysis, clinical risk factors associated with intraoperative saddle nose were female gender (OR 3.39; 95% CI 1.76-6.54; p < 0.01), severe caudal septal deviation (OR 2.22; 95% CI 1.30-3.79; p = 0.003), and intraoperative finding of septal cartilage fracture (OR 3.96; 95% CI 1.92-8.19; p < 0.01). CONCLUSIONS: Severe caudal septal deviation, intraoperative fracture of septal cartilage, and female gender were risk factors for intraoperative saddle nose deformity in our study population.

Clinical significance of IgG4 in sinonasal and skull base inflammatory pseudotumor.

INTRODUCTION: Inflammatory pseudotumor (IPT) in the sinonasal cavity and skull base region is benign non-neoplastic inflammatory process. However, IPT can mimic malignant tumor or infectious disease and there are difficulties in confirmation of diagnosis. The aim of study is to evaluate the clinical significance of immunoglobulin G4 (IgG4) in IPT in terms of steroid response and differential diagnosis with other skull base infiltrative lesions. METHODS: Medical records were reviewed retrospectively from 1998 to 2016. Subjects diagnosed with IPT by surgical biopsy were enrolled. IgG4 positivity was defined as IgG4/IgG ratio > 0.4. Additionally, IgG4/IgG ratio was calculated in eight skull base osteomyelitis (SBO) patients. RESULTS: Twenty-six IPT patients were included and the average age was 52.3 years, and 57.7% were male and 42.3% were female. Most lesions were involved in the sinuses (88.5%) and the incidence of extension beyond the sinuses itself was as follows: the cheek/hard palate/parapharynx (15.4%), orbit (61.5%), skull base (57.7%), and dura or brain (23.1%). All IPT cases revealed IgG4 + plasma cells and IgG4/IgG ratio over 0.4 was detected in 42.3% (11/26) of cases. In case of SBO, no patients had IgG4/IgG ratio exceed 0.4. Main treatment modality was systemic steroids (61.5%) and other modalities were used: surgery (3.8%), immunosuppressant (7.7%), radiotherapy (30.8%), or a combination of these modalities (15.4%). Steroid responses were not significantly different, but IgG4-positive group tended to have better response to steroid therapy. CONCLUSIONS: IgG4-positive and IgG4-negative IPT patients revealed no differences in involvement sites, clinical course, and steroid responses. However, IgG4/IgG ratio and IgG4 + plasma cell count can provide a diagnostic clue for infiltrative skull base lesions such as IPT and a differential diagnosis of SBO.

CT-Based Morphological Analysis of Isolated Inferior and Medial Blow-out Orbital Fractures in Korean Adults.

PURPOSE: To evaluate morphologic differences in isolated inferior medial orbital wall fractures (OWF) based on computed tomography scans. METHODS: This was a retrospective observational case study of 22 patients with an isolated inferior OWF and 32 patients with an isolated medial fracture between January 2008 and August 2010. We analyzed patient demographics and bony radiologic characteristics on CT scans, including the length and height of the lamina papyracea, the number of ethmoid air cell septa, the length of the anterior and posterior border of the orbital floor, the thickness of the orbital floor maxillary bone, and the axial length of the eyeball. RESULTS: There were no significant differences in sex, laterality, or concomitant intraocular injury between the two groups. The anteroposterior length (p = 0.391), the number of ethmoid septa (p = 0.869), and the thickness of the orbital floor (p = 0.419) did not differ significantly. The anterior (p < 0.001) or posterior (p = 0.014) height of the lamina papyracea, the lamina papyracea area (p < 0.001), and the lamina papyracea area/ethmoid air cell septa (p = 0.024) were significantly higher in the medial OWF group, while the anterior (p = 0.026) or posterior (p < 0.001) border length of the orbital floor and the axial length (p = 0.047) and volume (p = 0.034) of the eyeball were longer and smaller, respectively, in the inferior OWF group. CONCLUSIONS: Patients with a longer anterior or posterior border of the orbital floor, a shorter axial length, and a smaller eyeball volume are more likely to incur an isolated inferior OWF than an isolated medial OWF.

Calf Circumference as an Indicator for Cystatin C Testing in Hospitalized Elderly Male Patients for Detecting Hidden Renal Impairment.

Serum creatinine is used to measure the estimated glomerular filtration rate (eGFR); however, it is influenced by muscle mass and may therefore overestimate renal function in patients with sarcopenia. We examined calf circumference (CC) as a convenient muscle mass evaluation tool that can potentially indicate the need to test for cystatin C instead of creatinine in elderly inpatients. We retrospectively reviewed the electronic health record of 271 inpatients aged 65 or over. CC was determined by measuring the thickest part of the nondominant calf. eGFRcys and eGFRcr were calculated using cystatin C and creatinine levels, respectively. We evaluated optimum CC cutoff values using the eGFRcys/eGFRcr ratio for detecting hidden renal impairment (HRI, defined as eGFRcr ≥ 60 mL/min/1.73 m2 but eGFRcys < 60 mL/min/1.73 m2). CC showed a significant positive correlation with the eGFRcys/eGFRcr ratio in both sexes. The areas under the receiver operating characteristic curve were 0.725 and 0.681 for males and females, respectively. CC cutoffs with a sensitivity or specificity of 90% or 95% might be used to detect HRI in males. In conclusion, utilizing the optimum cutoff, CC could be a cost-effective screening tool for detecting HRI in elderly male patients using cystatin C as an add-on test.

The Association Between Total Protein Intake and All-Cause Mortality in Middle Aged and Older Korean Adults With Chronic Kidney Disease.

Background and Aims: Over the past decades, the optimum protein intake for patients with chronic kidney disease (CKD) has been an important, controversial issue. Dietary protein restriction has been commonly recommended for patients with CKD for preserving kidney function. However, evidence of the associations between long-term protein intake and mortality is not consistent in patients with CKD. Therefore, we aimed to examine the associations between total protein intake and all-cause mortality in Korean adults with CKD. Methods: From three sub-cohorts of the Korean Genome and Epidemiology Study (KoGES) starting from 2001, total 3,892 participants with eGFR < 60 mL/min/1.73 m2 (CKD stage 3-5) were included in this study. Dietary data were collected using food-frequency questionnaires at baseline. Deaths were followed from 2001 to 2019. Cox proportional hazards regression model was used to evaluate the association between protein intake and all-cause mortality. Results: During a median follow-up (min-max) of 11.1 years (0.3-15.1), 602 deaths due to all causes of mortality were documented. After adjustment for covariates, higher total protein intake was not associated with all-cause mortality [highest vs. lowest quintile of total protein intake (g/kg/day) and proportion (%) (Q5 vs. Q1), HR = 1.14 (0.75-1.72), and HR = 0.87 (0.67-1.13)] in CKD stage 3-5 patients. Conclusion: Dietary protein intake was not associated with mortality from all causes in patients with CKD. Further research is needed to establish optimal protein intake levels and examine the impact of the dietary source of protein on various health outcomes and mortality in CKD.

Implementation of a Sense of Home in High-Density Multicultural Singapore Nursing Homes: Challenges and Opportunities.

Many studies have introduced principles for creating a sense of home in nursing homes, yet they mostly feature cases from low-density developments in Western countries. This raises a question about how those principles are interpreted and implemented in other cultural contexts, especially in high-density, multicultural environments such as Singapore. This paper examines how a sense of home is implemented in Singapore nursing homes, with a specific focus on the role of the built environment. Participant observations were conducted in five nursing homes in Singapore comprising various architectural design typologies, with the focus on the residents' everyday interactions with their built environment. The study identified the extent of the presence of a sense of home in Singapore's nursing homes and the prevalence of an institutional care model. More specifically, the study explicates Singapore nursing home residents' management of privacy and personalization in shared spaces, illuminates the need for holistic implementation of homelike environments integrated with building designs and care programs and reiterates the pivotal role of social relationships in fostering a sense of home for the residents in the nursing homes.

Establishment of muscle mass-based indications for the cystatin C test in renal function evaluation.

Background: We aimed to suggest muscle mass-based criteria for using of the cystatin C test for the accurate estimated glomerular filtration rate (eGFR). Materials and methods: We recruited 138 Korean subjects and evaluated eGFRcr (derived from Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) based on creatinine) was compared to eGFRcys based on cystatin C as the reference value. The skeletal muscle mass index (SMI) by bioelectrical impedance analysis (BIA) was used as representative of muscle mass. Calf circumference (CC) was also evaluated. We defined the patients by eGFRcr as those with values of eGFRcr ≥ 60 mL/min/1.73 m2 but eGFRcys < 60 mL/min/1.73 m2 as the detection of hidden renal impairment (DHRI). Cut-off values were determined based on muscle mass for the cases of DHRI suggesting the criteria of cystatin C test in renal function evaluation. Results: We confirmed significant negative correlation between %difference of eGFRcr from eGFRcys and SMI (r, -0.592 for male, -0.484 for female) or CC (r, -0.646 for male, -0.351 for female). SMI of 7.3 kg/m2 for males and 5.7 kg/m2 for females were suggested to be significant cutoffs for indication of cystatin C test. We also suggested CC would be valuable for cystatin C indication. Conclusion: We suggested the muscle mass-based objective criteria relating to SMI and CC that would indicate the use of cystatin C to evaluate renal function test in sarcopenic cases. Our results highlight the importance of muscle mass-based selection of renal function.

Development of magnetic bearing system for a new third-generation blood pump.

A magnetic bearing system is a crucial component in a third-generation blood pump, particularly when we consider aspects such as system durability and blood compatibility. Many factors such as efficiency, occupying volume, hemodynamic stability in the flow path, mechanical stability, and stiffness need to be considered for the use of a magnetic bearing system in a third-generation blood pump, and a number of studies have been conducted to develop novel magnetic bearing design for better handling of these factors. In this study, we developed and evaluated a new magnetic bearing system having a motor for a new third-generation blood pump. This magnetic bearing system consists of a magnetic levitation compartment and a brushless direct current (BLDC) motor compartment. The active-control degree of freedom is one; this control is used for controlling the levitation in the axial direction. The levitation in the radial direction has a passive magnetic levitation structure. In order to improve the system efficiency, we separated the magnetic circuit for axial levitation by using a magnetic circuit for motor drive. Each magnetic circuit in the bearing system was designed to have a minimum gap by placing mechanical parts, such as the impeller blades, outside the circuit. A custom-designed noncontact gap sensor was used for minimizing the system volume. We fabricated an experimental prototype of the proposed magnetic bearing system and evaluated its performance by a control system using the Matlab xPC Target system. The noncontact gap sensor was an eddy current gap sensor with an outer diameter of 2.38 mm, thickness of 0.88 mm, and resolution of 5 µm. The BLDC motor compartment was designed to have an outer diameter of 20 mm, length of 28.75 mm, and power of 4.5 W. It exhibited a torque of 8.6 mNm at 5000 rpm. The entire bearing system, including the motor and the sensor, had an outer diameter of 22 mm and a length of 97 mm. The prototype exhibited sufficient levitation performance in the stop state and the rotation state with a gap of 0.2 mm between the rotor and the stator. The system had a steady position error of 0.01 µm in the stop state and a position error of 0.02 µm at a rotational speed of 5000 rpm; the current consumption rates were 0.15 A and 0.17 A in the stop state and the rotation state, respectively. In summary, we developed and evaluated a unique magnetic bearing system with an integrated motor. We believe that our design will be an important basis for the further development of the design of an entire third-generation blood pump system.

Sodium alginate hydrogel-based bioprinting using a novel multinozzle bioprinting system.

Bioprinting is a technology for constructing bioartificial tissue or organs of complex three-dimensional (3-D) structure with high-precision spatial shape forming ability in larger scale than conventional tissue engineering methods and simultaneous multiple components composition ability. It utilizes computer-controlled 3-D printer mechanism or solid free-form fabrication technologies. In this study, sodium alginate hydrogel that can be utilized for large-dimension tissue fabrication with its fast gelation property was studied regarding material-specific printing technique and printing parameters using a multinozzle bioprinting system developed by the authors. A sodium alginate solution was prepared with a concentration of 1% (wt/vol), and 1% CaCl(2) solution was used as cross-linker for the gelation. The two materials were loaded in each of two nozzles in the multinozzle bioprinting system that has a total of four nozzles of which the injection speed can be independently controlled. A 3-D alginate structure was fabricated through layer-by-layer printing. Each layer was formed through two phases of printing, the first phase with the sodium alginate solution and the second phase with the calcium chloride solution, in identical printing pattern and speed condition. The target patterns were lattice shaped with 2-mm spacing and two different line widths. The nozzle moving speed was 6.67 mm/s, and the injection head speed was 10 µm/s. For the two different line widths, two injection needles with inner diameters of 260 and 410 µm were used. The number of layers accumulated was five in this experiment. By varying the nozzle moving speed and the injection speed, various pattern widths could be achieved. The feasibility of sodium alginate hydrogel free-form formation by alternate printing of alginate solution and sodium chloride solution was confirmed in the developed multinozzle bioprinting system.

Analysis of pulsatile and nonpulsatile blood flow effects in different degrees of stenotic vasculature.

Vessel lumens that have been chronically narrowed by atherosclerosis should be increased in flow velocity and intrastenotic area pressure to maintain an equal flow. This might be followed by a decrease in hemodynamic energy, leading to a reduction of tissue perfusion. In this study, we compared hemodynamic energies according to degrees of stenotic vasculature between pulsatile flow and nonpulsatile flow. Cannuale with 25, 50, and 75% diameter stenosis (DS) were located at the outlet cannula. Using the Korea Hybrid ventricular assist device (KH-VAD) (pulsatile pump: group A) and Biopump (nonpulsatile pump: group B), constant flow of 2 L/min was maintained then real-time flow and velocity in the proximal and distal part of the stenotic cannula were measured. The hemodynamic energies of two groups were compared. At 75% DS, proximal energy equivalent pressure (EEP) delivered to the distal end was only 41.9% (group A) and 42.5% (group B). As the percent EEP fell below 10%, pulsatility disappeared from the 50% stenosis in group A. The surplus hemodynamic energy (SHE) of group B at all degrees of stenosis must have been 0, which was also the case of group A at 75% stenosis. This research evaluated the hemodynamic energy on various degrees of DS in both pulsatile and nonpulsatile flow with mock system. Using a pulsatile pump, pulsatility disappeared above 50% DS while hemodynamic energy was maintained. Therefore, our results suggest that pulsatile flow has a better effect than nonpulsatile flow in reserving hemodynamic energy after stenotic lesion.

The effect of fluid viscosity on the hemodynamic energy changes during operation of the pulsatile ventricular assist device.

Blood viscosity during operation of ventricular assist device (VAD) can be changed by various conditions such as anemia. It is known generally that the blood viscosity can affect vascular resistance and lead to change of blood flow. In this study, the effect of fluid viscosity variation on hemodynamic energy was evaluated with a pulsatile blood pump in a mock system. Six solutions were used for experiments, which were composed of water and glycerin and had different viscosities of 2, 2.5, 3, 3.5, 4, and 4.5 cP. The hemodynamic energy at the outlet cannula was measured. Experimental results showed that mean pressure was increased in accordance with the viscosity increase. When the viscosity increased, the mean pressure was also increased. However, the flow was decreased according to the viscosity increase. Energy equivalent pressure value was increased according to the viscosity-induced pressure rise; however, surplus hemodynamic energy value did not show any apparent changing trend. The hemodynamic energy made by the pulsatile VAD was affected by the viscosity of the circulating fluid.

A durability study of a paracorporeal pulsatile electro-mechanical pneumatic biventricular assist device.

In 2002, the paracorporeal pulsatile electro-mechanical pneumatic ventricular assist device (VAD) began to be developed by the Korea Artificial Organ Center at Korea University under a Health & Medical Technology Research and Development program which finished in 2008. In vitro durability testing was conducted on the paracorporeal pulsatile pneumatic VAD to determine device durability and to evaluate device failures. The 1- and 2-year reliability of the paracorporeal pulsatile pneumatic VAD was shown to be 91.2% and 54.9%, respectively, with an 80% confidence level. Failure modes were analyzed using fault tree analysis, with customized software continuously acquiring data during the test period. After this period, 21 in vivo animal tests were done, with 14 cases of left atrium to left ventricle (LV) inflow cannulation (36Fr)/outflow grafting to descending aorta, and seven cases of apex cannulation of LV to descending aorta (12 mm). The longest postoperative day (182 days) in Korea was recently recorded in in vivo animal testing (bovine, 90 kg, male, 3.5-4.0 L/min flow rate, and 55 bpm).

Long-Term Clinical Course of Benign Fibro-Osseous Lesions in the Paranasal Sinuses.

OBJECTIVES: Fibro-osseous lesions of the paranasal sinuses can present various clinical manifestations. This study aimed to report the long-term clinical course of benign fibro-osseous lesions (BFOLs) in the paranasal sinuses, including clinical and radiologic features. METHODS: Radiologically confirmed BFOLs between 1994 and 2016, with the exclusion of osteoma cases, were retrospectively reviewed. We compared demographic characteristics between the surgery and observation groups. The reasons for the imaging study, radiographic features, histopathology, and clinical course based on serial image scans were analyzed. RESULTS: In total, 183 subjects were selected from a thorough review of head and neck radiologic tests (n=606,068) at a tertiary referral hospital over 22 years. Patients' mean age was 28.6±18.1 years, and 56.3% were males. A diagnostic imaging workup was performed in 55.7% of patients due to facial asymmetry, headache, skull mass, or other symptoms related to BFOLs. In other patients (37.7%), BFOLs were found incidentally on computed tomography or magnetic resonance imaging. The most common diagnosis was fibrous dysplasia, followed by ossifying fibroma, based on both radiologic exams and histopathologic results. In total, 42.6% of the patients underwent surgery because of subjective symptoms or esthetic concerns. The patients who underwent surgery were younger (P<0.001) and had a longer follow-up duration (P<0.001) than those who underwent observation. Patients who experienced lesion growth (11.5%) were younger (P<0.001) and had more lesion sites (P=0.018) than those who did not, regardless of surgical treatment. Five patients underwent optic nerve decompression, and one patient experienced malignant transformation. CONCLUSION: BFOL in the paranasal sinuses is a rare disease, and most cases were observed without specific treatment. Surgical treatment should be considered in symptomatic patients with aggressive clinical features. Regular observation and management are needed, particularly in younger patients in their teens.

A three-dimensional bioprinting system for use with a hydrogel-based biomaterial and printing parameter characterization.

Bioprinting is an emerging technology for constructing tissue or bioartificial organs with complex three-dimensional (3D) structures. It provides high-precision spatial shape forming ability on a larger scale than conventional tissue engineering methods, and simultaneous multiple components composition ability. Bioprinting utilizes a computer-controlled 3D printer mechanism for 3D biological structure construction. To implement minimal pattern width in a hydrogel-based bioprinting system, a study on printing characteristics was performed by varying printer control parameters. The experimental results showed that printing pattern width depends on associated printer control parameters such as printing flow rate, nozzle diameter, and nozzle velocity. The system under development showed acceptable feasibility of potential use for accurate printing pattern implementation in tissue engineering applications and is another example of novel techniques for regenerative medicine based on computer-aided biofabrication system.

Optimal moving angle of pusher plate in occlusive-type pulsatile blood pump.

Since the occlusive-type pulsatile extracorporeal blood pump (Twin-Pulse Life Support System; Seoul National University, Seoul, Korea) received the CE mark of the European Directives and Korea Food and Drug Administration approval (2004) for short-term applications as an extracorporeal life support system, the pump system has been tested for hemolysis. This pump system was recently upgraded with an ameliorated pusher plate to reduce hemolysis. In this study, numerical analysis and in vitro tests were performed to determine the optimal conditions for increasing the durability of the blood sac and pump output. During the simulation, the minimum sliding interface force (SIF) for the angle of the pusher plate movement (PPM) was calculated (40-70 degrees ). In the in vitro durability test, the angle of the PPM was increased gradually from 40 to 70 degrees in 10 degrees increments, and the mean time to failure (MTTF) of the blood sac was calculated. Fifteen tests were conducted for each case: 40, 50, 60, and 70 degrees (n = 15 each). The MTTF of the blood sac was defined as the time when a crack of the blood sac occurred. The longer lifetime of the blood sac at 60 degrees of the PPM (297.0 h) than that at 50 degrees (197.6 h) was attributed to the lower SIF value (-0.13, normalized value) at 60 degrees of the PPM.

Endoscopic Optic Nerve Decompression for Optic Neuropathy in Sinonasal Fibro-Osseous Tumors.

BACKGROUND: Sinonasal fibro-osseous tumors involving the skull base sometimes result in the encasement of the optic canal and can cause the compressive optic neuropathy. This study aimed to elucidate the optimal timing of endoscopic optic nerve decompression (OND) in cases with optic neuropathy caused by fibro-osseous tumors. METHODS: Medical records were reviewed retrospectively from July 2008 through November 2016. Subjects who underwent surgery with endoscopic OND for optic neuropathy caused by fibro-osseous lesions were enrolled. Pre- and postoperative ophthalmologic evaluation were analyzed, including best-corrected visual acuity, visual field testing, and color vision. RESULTS: A total of 9 patients underwent OND. Seven patients had fibrous dysplasia and 2 patients had juvenile ossifying fibroma. Patients included 6 boys and 3 girls. The average age was 15 years with a range of 8-17 years. Symptom duration ranged from 2 months to 4 years. The mean follow-up period was 28 months (range, 0.8-76.4 months). There was no immediate deteriorated vision after OND. Eight eyes (88.9%) were improved and 1 eye (11.1%) had only visual field improvement. However, patients whose visual impairment was in the range of finger count and hand motion were not recovered beyond the quantitatively measurable level even after OND. CONCLUSIONS: Endoscopic OND in patients with optic neuropathy caused by a fibro-osseous tumor in the sinonasal region is safe and worth trying to improve visual outcomes. Early therapeutic OND is recommended before the patient's visual function is decreased below quantitatively measurable vision.

Development of an algorithm to regulate pump output for a closed air-loop type pneumatic biventricular assist device.

The closed air space-type of extracorporeal pneumatic ventricular assist device (VAD) developed by the Korea Artificial Organ Center utilizes a bellows-transforming mechanism to generate the air pressure required to pump blood. This operating mechanism can reduce the size and weight of the driving unit; however, the output of the blood pump can be affected by the pressure loading conditions of the blood sac. Therefore, to guarantee a proper pump output level, regardless of the pressure loading conditions that vary over time, automatic pump output regulation of the blood pump is required. We describe herein a pump output regulation algorithm that was developed to maintain pump output around a reference level against various afterload pressures, and verified the pump performance in vitro. Based on actual operating conditions in animal experiments, the pumping rate was limited to 40-84 beats per minute, and the afterload pressure was limited to 80-150 mm Hg. The tested reference pump output was 4.0 L/min. During experiments, the pump output was successfully and automatically regulated within the preset area regardless of the varying afterload conditions. The results of this preliminary experiment can be used as the basis for an automatic control algorithm that can enhance the stability and reliability of the applied VAD.

Optimal pressure regulation of the pneumatic ventricular assist device with bellows-type driver.

The bellows-type pneumatic ventricular assist device (VAD) generates pneumatic pressure with compression of bellows instead of using an air compressor. This VAD driver has a small volume that is suitable for portable devices. However, improper pneumatic pressure setup can not only cause a lack of adequate flow generation, but also cause durability problems. In this study, a pneumatic pressure regulation system for optimal operation of the bellows-type VAD has been developed. The optimal pneumatic pressure conditions according to various afterload conditions aiming for optimal flow rates were investigated, and an afterload estimation algorithm was developed. The developed regulation system, which consists of a pressure sensor and a two-way solenoid valve, estimates the current afterload and regulates the pneumatic pressure to the optimal point for the current afterload condition. Experiments were performed in a mock circulation system. The afterload estimation algorithm showed sufficient performance with the standard deviation of error, 8.8 mm Hg. The flow rate could be stably regulated with a developed system under various afterload conditions. The shortcoming of a bellows-type VAD could be handled with this simple pressure regulation system.

Development of a closed air loop electropneumatic actuator for driving a pneumatic blood pump.

In this study, we developed a small pneumatic actuator that can be used as an extracorporeal biventricular assist device. It incorporated a bellows-transforming mechanism to generate blood-pumping pressure. The cylindrical unit is 88 +/- 0.1 mm high, has a diameter of 150 +/- 0.1 mm, and weighs 2.4 +/- 0.01 kg. In vitro, maximal outflow at the highest pumping rate (PR) exceeded 8 L/min when two 55 mL blood sacs were used under an afterload pressure of 100 mm Hg. At a pumping rate of 100 beats per minute (bpm), maximal hydraulic efficiency was 9.34% when the unit supported a single ventricle and 13.8% when it supported both ventricles. Moreover, pneumatic efficiencies of the actuator were 17.3% and 33.1% for LVAD and BVAD applications, respectively. The energy equivalent pressure was 62.78 approximately 208.10 mm Hg at a PR of 60 approximately 100 bpm, and the maximal value of dP/dt during systole was 1269 mm Hg/s at a PR of 60 bpm and 979 mm Hg/s at a PR of 100 bpm. When the unit was applied to 15 calves, it stably pumped 3 approximately 4 L/min of blood at 60 bpm, and no mechanical malfunction was experienced over 125 days of operation. We conclude that the presently developed pneumatic actuator can be utilized as an extracorporeal biventricular assist device.

Endoscopic 2-Port Technique for Infratemporal Fossa Tumors: Using Prelacrimal Medial Maxillectomy and Caldwell-Luc Approach.

BACKGROUND: The endoscopic endonasal approach to the infratemporal fossa (ITF) has gained popularity. However, the inferior turbinate and/or lacrimal duct are often removed when performing endoscopic medial maxillectomy for ITF approach, and there is potential risk for empty nose syndrome or epiphora. Although the endoscopic prelacrimal recess approach was introduced to avoid these complications, there were some limitations associated with surgical freedom. We report a 2-port endoscopic technique using both prelacrimal recess and antral window as a means to preserve the inferior turbinate and lacrimal duct, while facilitating instrument availability during ITF tumor resection. METHODS: We retrospectively reviewed 3 patients between September 2016 and May 2018 who were treated with a modified 2-port technique for ITF tumors. RESULTS: There was 1 case of trigeminal schwannoma originating in the mandibular nerve, 1 recurrent meningioma, and 1 paraganglioma. The 2-port technique was not initially planned in these 3 cases, but it was decided to use the technique during surgery because tumors were extensively attached to surrounding muscles and had profuse bleeding. After tumor resection, sinonasal anatomy including inferior turbinate and lacrimal duct was well preserved. CONCLUSIONS: We propose a hybrid endoscopic surgical procedure for ITF tumors using both endoscopic prelacrimal recess approach and transantral window. This technique provides surgeons an adequate working space via a bimanual technique through 2 different ports, while preserving normal sinonasal structures.