Improvement of Transfusion Practice in Cardiothoracic Surgery Through Implementing a Patient Blood Management Program.

Background: In this study, we examined the impact of a patient blood management (PBM) program on red blood cell (RBC) transfusion practices in cardiothoracic surgery. Methods: The PBM program had 3 components: monitoring transfusions through an order communication system checklist, educating the medical team about PBM, and providing feedback to ordering physicians on the appropriateness of transfusion. The retrospective analysis examined changes in the hemoglobin levels triggering transfusion and the proportions of appropriate RBC transfusions before, during, and after PBM implementation. Further analysis was focused on patients undergoing cardiac surgery, with outcomes including 30-day mortality, durations of intensive care unit and hospital stays, and rates of pneumonia, sepsis, and wound complications. Results: The study included 2,802 patients admitted for cardiothoracic surgery. After the implementation of PBM, a significant decrease was observed in the hemoglobin threshold for RBC transfusion. This threshold dropped from 8.7 g/dL before PBM to 8.3 g/dL during the PBM education phase and 8.0 g/dL during the PBM feedback period. Additionally, the proportion of appropriate RBC transfusions increased markedly, from 23.9% before PBM to 34.9% and 58.2% during the education and feedback phases, respectively. Among the 381 patients who underwent cardiac surgery, a significant reduction was noted in the length of hospitalization over time (p<0.001). However, other clinical outcomes displayed no significant differences. Conclusion: PBM implementation effectively reduced the hemoglobin threshold for RBC transfusion and increased the rate of appropriate transfusion in cardiothoracic surgery. Although transfusion practices improved, clinical outcomes were comparable to those observed before PBM implementation.

Perioperative Red Blood Cell Transfusion Is Associated With Adverse Cardiovascular Outcomes in Heart Valve Surgery.

BACKGROUND: We examined the relationship between blood transfusion and long-term adverse events to evaluate the clinical impact of red blood cell (RBC) transfusion on patients undergoing cardiac valve surgery. METHODS: From the National Health Insurance Service database, individuals undergoing heart valve surgery were verified, including aortic valve (AV), mitral valve (MV), tricuspid valve (TV), and complex valves (more than 2 valve surgeries). The interested outcomes were incidence of death, ischemic stroke, hemorrhagic stroke, and admission for myocardial infarction during follow-up. Associations between perioperative RBC transfusion and long-term cardiovascular events were analyzed with Cox-proportional hazard model. RESULTS: Perioperative RBC transfusion (±2 days from the day of surgery) was categorized into 0, 1, 2, and >3 units based on the number of packs transfused. From 2003 to 2019, the data of 58,299 individuals were retrieved (51.6% were male and 58% were aged above 60 years). The median follow-up duration was 5.53 years. Of the total cohort, 86.5% received at least 1 transfusion. In multivariable analysis, adverse cardiovascular event risk proportionally increased with transfusion in a dose-dependent manner. The adjusted hazard ratios and 95% confidence intervals of outcomes after the transfusion of 1, 2, and ≥3 units compared to those with no transfusion were as follows: death, 1.53 (1.41-1.66), 1.97 (1.81-2.14), and 3.03 (2.79-3.29); ischemic stroke, 1.27 (1.16-1.39), 1.31 (1.19-1.44), and 1.51 (1.38-1.66); hemorrhagic stroke, 1.38 (1.16-1.66), 1.71 (1.43-2.05), and 2.31 (1.94-2.76); and myocardial infarction 1.35 (1.13-1.62), 1.60 (1.33-1.91), and 1.99 (1.66-2.38), respectively (all P < .01). CONCLUSIONS: In the analysis of the national cohort, perioperative RBC transfusion during heart valve surgery was associated with adverse cardiovascular outcomes correlated with the volume of RBC transfusion.

A Watch-Type Electrocardiography Is a Reliable Tool for Detecting Paroxysmal Cardiac Arrhythmias.

Background: A substantial proportion of cardiac arrhythmias are paroxysmal in nature, and 12-lead electrocardiography (ECG) and Holter monitoring often fail to detect paroxysmal arrhythmias. We designed and evaluated a watch-type, electrocardiograph-recording, wearable device (w-ECG) to overcome the limitations of 12-lead ECG and Holter monitoring. Methods: We prospectively enrolled 96 patients with symptoms assumed to be related to cardiac arrhythmias. Electrocardiography recording was performed with both the w-ECG and Holter monitoring. Detection of any arrhythmia was the primary outcome endpoint and was compared between the w-ECG and Holter monitoring. Results: Any arrhythmia was detected in 51 (53.1%) and 27 (28.1%) patients by the w-ECG and Holter monitoring, respectively (odds ratio (OR) = 2.9, p < 0.001). The w-ECG was superior to Holter monitoring for the detection of clinically significant arrhythmias (excluding atrial premature contraction, ventricular premature contraction, and non-sustained atrial tachyarrhythmia) (OR = 2.34, p = 0.018). In 27 (28.1%) patients, cardiac arrhythmias were detected only by the w-ECG, with atrial fibrillation being the most frequent case (13 patients). Based on ECGs recorded by using the w-ECG, 17 patients (17.7%) received therapeutic interventions, including radiofrequency catheter ablation. Conclusions: The w-ECG is capable of recording ECGs of good quality, with a discernable P wave and distinguishable QRS morphology. The ability of the w-ECG to detect cardiac arrhythmias was significantly better than that of Holter monitoring, and a significant proportion of patients received therapeutic intervention based on ECGs recorded by the w-ECG.

Association Between Hypertension and Incident Infective Endocarditis.

BACKGROUND: This study aimed to evaluate the association of hypertension with incident infective endocarditis (IE) by investigating the incidence of IE according to blood pressure levels using the National Health Insurance Service database. METHODS: The data of 4 080 331 individuals linked to the health screening database in 2009 were retrieved (males, 55.08%; mean age, 47.12±14.13 years). From 2009 to 2018, the risk factors for the first episode of IE were investigated. Hypertension was categorized into normotension, prehypertension, hypertension, and hypertension with medication. The Cox proportional hazard model assessed the effect of blood pressure level during the health screening exam on incident IE. RESULTS: During the 9-year follow-up, 812 (0.02%) participants were diagnosed with IE. The incidence rates of IE in the normotension, prehypertension, hypertension, and hypertension with medication groups were 0.9, 1.4, 2.6, and 6.0 per 100 000 person-years, respectively. Those with prehypertension, hypertension, and hypertension with medication were correlated with an increased risk of IE in a dose-response manner compared with the normotension group (hazard ratio, 1.33 [95% CI, 1.06-1.68]; hazard ratio, 1.98 [1.48-2.66]; hazard ratio, 2.56 [2.02-3.24], respectively, all P<0.001). CONCLUSIONS: In a large national cohort study with an average follow-up of 9 years, increased blood pressure was identified as a risk factor for incident IE in a dose-dependent manner. Hypertension increases the public health care burden by acting as a risk factor for rare infective heart diseases.

Compressed Deep Learning to Classify Arrhythmia in an Embedded Wearable Device.

The importance of an embedded wearable device with automatic detection and alarming cannot be overstated, given that 15-30% of patients with atrial fibrillation are reported to be asymptomatic. These asymptomatic patients do not seek medical care, hence traditional diagnostic tools including Holter are not effective for the further prevention of associated stroke or heart failure. This is likely to be more so in the era of COVID-19, in which patients become more reluctant on hospitalization and checkups. However, little literature is available on this important topic. For this reason, this study developed efficient deep learning with model compression, which is designed to use ECG data and classify arrhythmia in an embedded wearable device. ECG-signal data came from Korea University Anam Hospital in Seoul, Korea, with 28,308 unique patients (15,412 normal and 12,896 arrhythmia). Resnets and Mobilenets with model compression (TensorFlow Lite) were applied and compared for the diagnosis of arrhythmia in an embedded wearable device. The weight size of the compressed model registered a remarkable decrease from 743 MB to 76 KB (1/10000), whereas its performance was almost the same as its original counterpart. Resnet and Mobilenet were similar in terms of accuracy, i.e., Resnet-50 Hz (97.3) vs. Mo-bilenet-50 Hz (97.2), Resnet-100 Hz (98.2) vs. Mobilenet-100 Hz (97.9). Here, 50 Hz/100 Hz denotes the down-sampling rate. However, Resnets took more flash memory and longer inference time than did Mobilenets. In conclusion, Mobilenet would be a more efficient model than Resnet to classify arrhythmia in an embedded wearable device.

Association between Cumulative Fluid Balance and Outcomes in Acute Respiratory Distress Syndrome Patients Treated with Extracorporeal Membrane Oxygenation.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) has become increasingly accepted as a life-saving procedure for patients with severe acute respiratory distress syndrome (ARDS). This study investigated the relationship between cumulative fluid balance (CFB) and outcomes in adult ARDS patients treated with ECMO. METHODS: We retrospectively analyzed the data of adult ARDS patients who received ECMO between December 2009 and December 2019 at Korea University Anam Hospital. CFB was calculated during the first 7 days after ECMO initiation. The primary endpoint was 28-day mortality. RESULTS: The 74 patients were divided into survivor (n=33) and non-survivor (n=41) groups based on 28-day survival. Non-survivors showed a significantly higher CFB at 1-7 days (p<0.05). Cox multivariable proportional hazard regression revealed a relationship between CFB on day 3 and 28-day mortality (hazard ratio, 3.366; 95% confidence interval, 1.528-7.417; p=0.003). CONCLUSION: In adult ARDS patients treated with ECMO, a higher positive CFB on day 3 was associated with increased 28-day mortality. Based on our findings, we suggest a restrictive fluid strategy in ARDS patients treated with ECMO. CFB may be a useful predictor of survival in ARDS patients treated with ECMO.

A Giant Pseudo-Aneurysm on the Anastomosis Site for a Redo Bentall Operation due to Behçet Disease Treated by Thoracic Endovascular Aortic Aneurysm Repair with a Custom-Made Stent Graft.

A 34-year-old man who had undergone aortic valve replacement 8 years ago underwent an additional Bentall operation due to mechanical valve dehiscence 2 years later. Subsequently, he was diagnosed with Behçet disease and Batter syndrome. A week after being hospitalized again due to chest pain and dyspnea, a large pseudo-aneurysm was detected on computed tomography. Because of the excessively large size of the pseudo-aneurysm, surgical treatment seemed very risky. Therefore, we planned to perform thoracic endovascular aortic repair (TEVAR) and treated him successfully. However, the patient experienced recurrence of the same symptoms 4 months later, and was found to have type IV endoleak. He received a TEVAR procedure again, and it was successful.

Management of Atrio-esophageal Fistula Induced by Radiofrequency Catheter Ablation in Atrial Fibrillation Patients: a Case Series.

Atrio-esophageal fistula (AEF) is one of the most devastating complication of radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) and surgical repair is strongly recommended. However, optimal surgical approach remains to be elucidated. We retrospectively reviewed AEF cases that occurred after RFCA in a single center and evaluated the clinical results of different surgical approach. Surgical or endoscopic repair was attempted in five AF patients who underwent RFCA. Atrio-esophageal fistula and mediastinal infection was not controlled in the patient who underwent endoscopic repair eventually died. Lethal cerebral air embolism occurred two days after surgery in a patient who underwent esophageal repair only. Primary surgical repair of both the left atrium (LA) and esophagus was performed in the remaining three patients. Among these three patients, two underwent external LA repair and the remaining had internal LA repair via open-heart surgery. External repair of the LA was unsuccessful and one patient dies and another had to undergo second operation with internal repair of the LA. The patient who underwent internal LA repair during the first operation survived without additional surgery. Furthermore, we applied veno-arterial extracorporeal membrane oxygenation (VA-ECMO) with artificial induction of ventricular fibrillation in this patient to prevent air and septic embolism and she had no neurologic sequelae. In summary, surgical correction can be considered preferentially to correct AEF. Open-heart surgical repair of LA from the internal side seems to be an acceptable surgical method. Application of VA-ECMO with artificial induction of ventricular fibrillation might be effective to prevent air and septic embolism.

Rescue Extracorporeal Bypass to Prevent Atrioesophageal Fistula-related Air Embolism.

Atrioesophageal fistula (AEF) is a rare but disastrous complication encountered after radiofrequency catheter ablation for atrial fibrillation or flutter. Furthermore cerebral air embolism due to AEF is considered a strong predictor of mortality. In our case a patient presented with AEF and cerebral air embolism. As a rescue effort ventricular fibrillation was induced and sustained under venoarterial extracorporeal membrane oxygenation support until emergency AEF repair was feasible. Herein we report the successful use of the above measures to prevent further air embolism in a patient with radiofrequency catheter ablation-related AEF.

Renal hemodynamics by return cannular position of extracorporeal membrane oxygenation in swine.

BACKGROUND: Whether arterial return cannula position affects the kidney during Veno-Arterial extracorporeal membrane oxygenation (ECMO) is unclear. Therefore, we compared hemodynamic parameters and acute kidney injury (AKI) biomarkers between ascending aorta return (aECMO) and femoral artery return ECMO (fECMO) in swine to evaluate the effect of cannula position on the kidney. METHODS: A total of twelve swines were allocated randomly into two groups. ECMO was maintained for 6h. Hemodynamic parameters including mean arterial pressure (MAP), renal arterial flow rate (AF), energy equivalent pressure (EEP), and surplus hemodynamic energy (SHE) were measured at the left renal artery. For evaluation of kidney injury, samples were obtained for blood urea nitrogen, creatinine, cystatin C, and neutrophil gelatinase-associated lipocalin (before ECMO, and 1, 3, and 6 h after initiating ECMO). RESULTS: Before the start of ECMO, hemodynamic parameters were not different between the two groups. With regard to the rate of change before and after ECMO, the fECMO group showed a significantly higher increase in MAP, AF, and EEP and a greater decrease in SHE than the aECMO group (P<0.001). In inter-group analysis, no significant difference in time-dependent trends were observed for biochemical laboratory levels. CONCLUSIONS: fECMO support was associated with a higher energy profile at the renal artery than that with aECMO, whereas pulsatility was decreased.

Atrial fibrillation classification based on convolutional neural networks.

BACKGROUND: The global age-adjusted mortality rate related to atrial fibrillation (AF) registered a rapid growth in the last four decades, i.e., from 0.8 to 1.6 and 0.9 to 1.7 per 100,000 for men and women during 1990-2010, respectively. In this context, this study uses convolutional neural networks for classifying (diagnosing) AF, employing electrocardiogram data in a general hospital. METHODS: Data came from Anam Hospital in Seoul, Korea, with 20,000 unique patients (10,000 normal sinus rhythm and 10,000 AF). 30 convolutional neural networks were applied and compared for the diagnosis of the normal sinus rhythm vs. AF condition: 6 Alex networks with 5 convolutional layers, 3 fully connected layers and the number of kernels changing from 3 to 256; and 24 residual networks with the number of residuals blocks (or kernels) varying from 8 to 2 (or 64 to 2). RESULTS: In terms of the accuracy, the best Alex network was one with 24 initial kernels (i.e., kernels in the first layer), 5,268,818 parameters and the training time of 89 s (0.997), while the best residual network was one with 6 residual blocks, 32 initial kernels, 248,418 parameters and the training time of 253 s (0.999). In general, the performance of the residual network improved as the number of its residual blocks (its depth) increased. CONCLUSION: For AF diagnosis, the residual network might be a good model with higher accuracy and fewer parameters than its Alex-network counterparts.

Clinical Course of Renal Disease in Recipients of Liver Transplant Who Required Peritransplant Dialysis.

PURPOSE: Renal dysfunction is a common complication and one of the factors that affects the outcomes of liver transplantation (LT). The aim of this study was to review the clinical course of recipients of LT who needed peritransplant dialysis at our center. METHODS: We compared the clinical demographics, morbidity, and mortality between patients who required and those who did not require peritransplant dialysis among 26 recipients of LT from May 2015 to February 2018 at our center. RESULTS: Among the recipients, 9 had pretransplant or posttransplant dialysis and 17 did not. The patients who underwent dialysis had a higher pretransplant Model for End-Stage Liver Disease score (42 vs 13; P < .001), older donor age (41 vs 24 years; P < .001), and longer post-LT hospital stay (37 vs 20 days; P < .001). However, there was no significant difference in the serum creatinine level between the 2 groups (1.36 vs 0.93 mg/dL; P = .187) at 2 weeks (1.10 vs 0.96 mg/dL; P = .341), 1 month (1.06 vs 0.86 mg/dL; P = .105), and 3 months after LT (0.92 vs 0.94 vs 0.89 mg/dL; P = .825). Mortality was higher in the peritransplant dialysis group (P = .043). The pre-LT dialysis duration was significantly related to post-LT dialysis (P = .028) and mortality (P = .011). CONCLUSIONS: The pre-LT dialysis duration is considered an important factor in the survival and recovery of kidney function after LT. Therefore, if the patient has started dialysis, it may be beneficial to proceed to LT as soon as possible.

Impact of resection margin length and tumor depth on the local recurrence after thoracoscopic pulmonary wedge resection of a single colorectal metastasis.

BACKGROUND: To evaluate the influence of tumor depth on preoperative computed tomography (CT) image, and resection margin length on local recurrence after pulmonary metastasectomy of colorectal cancer. METHODS: Patients undergoing thoracoscopic pulmonary wedge resection for single pulmonary metastasis of colorectal cancer origin from 2007 to 2017 were analyzed. Factors such as resection margin, tumor size and depth were analyzed. The local recurrences of two subgroups based on the pulmonary resection margin (Group 1: resection margin 1-10 mm or shorter than the tumor size, Group 2: resection margin >10 mm or at least greater than the tumor size) were analyzed. RESULTS: Sixty-five patients were included in this study. The local recurrence rate was 12/65 (18.5%). Median follow up period was 33 months. Median tumor size and depth on preoperative CT were 1.1 and 1.6 cm. Median length of resection margin was 0.5 cm (group 1: 0.4 cm, group 2: 1.0 cm, P<0.001). No difference was noted in 3-year local recurrence-free survival (80.8% vs. 76.7%, P=0.756) between the two subgroups. No significant correlation was noted between the length of resection margin and the tumor size and depth. However, tumor depth was an independent factor related to higher local recurrence on multivariate analysis. CONCLUSIONS: Extent of resection margin in pulmonary metastasectomy does not seem to affect significantly on the local recurrence if complete resection is accomplished. However, preoperative tumor depth on CT image and postoperative distant metastasis seem to affect on local recurrence after pulmonary metastasectomy.

Current Status of Off-pump Coronary Artery Bypass Grafting in Patients with Multiple Coronary Artery Disease Compared with On-pump Coronary Artery Bypass Grafting: The Korean National Cohort Study.

BACKGROUND: Despite advance in off-pump coronary artery bypass (OPCAB) grafting, there are large debating issues regarding survival benefit between OPCAB and on-pump coronary artery bypass grafting (CABG). The aim of this study is to address appropriateness of OPCAB approach in patients with ischemic heart disease having multiple vessels using South Korea national cohort data. METHODS: To evaluate the safety and efficacy of OPCAB, we accessed all causes of death, late repeat revascularization, hospitalization for cerebrovascular accident (CVA), and new renal replacement therapy in patients who underwent isolated CABG with multiple grafting (≥2 grafts) and who were registered in the Korean Health Insurance Review and Assessment Service Database between April 2011 and September 2014. RESULTS: OPCAB was performed in 4,692 patients and on-pump CABG in 2,999 patients from 82 hospitals in South Korea. On multivariable analysis, on-pump CABG was associated with a significantly higher adjusted risk of overall all-cause death (hazard ratio [HR]: 1.876, 95% confidence interval [CI]: 1.587-2.216, p < 0.001) and initiation of new renal replacement therapy (HR: 1.618, 95% CI: 1.124-2.331, p = 0.009). However, we observed no significant difference in repeat revascularization and hospitalization for CVA between the two groups. In propensity score matching, matched patients (2,940 pairs) showed results similar to multivariable analysis that on-pump CABG was associated with a higher overall mortality and initiation of new renal replacement therapy (p < 0.001). CONCLUSION: In this study, we found that OPCAB was associated with better survival rates and renal preservation compared with on-pump CABG.

Influence of cannula positioning on brain injury during extracorporeal membrane oxygenation.

BACKGROUND: In veno-arterial extracorporeal membrane oxygenation (V-A ECMO), a patient is cannulated using either an atrio-aortic technique (central type ECMO; cECMO) or a femoro-femoral technique (peripheral type ECMO; pECMO). The direction of the pump flow at the aortic arch is anterograde from the ascending aorta in cECMO and retrograde from the descending aorta in pECMO. Hemodynamic differences from the position of the cannulas may influence the brain differently. To evaluate the effect of ECMO cannula positioning on the brain, hemodynamic data and plasma biomarkers were collected. METHODS: Eight pigs were randomly divided into the cECMO group (n=4) or pECMO group (n=4). ECMO was administered for 6 hours at a pump flow rate based on the mean flow of the ascending aorta. Mean arterial pressure (MAP), mean arterial flow (MAF), energy equivalent pressure (EEP), and surplus hemodynamic energy (SHE) were measured in the brachiocephalic artery every 30 minutes. During ECMO treatment, plasma was collected for analysis of interleukin-6 (IL-6), S100B, glial fibrillary acidic protein (GFAP), and neuron-specific enolase. The data were analyzed using the Mann-Whitney U tests, and repeated measures ANOVAs; significance was set at P<0.05. RESULTS: MAP and EEP at 1 and at 3 hours, MAF at all measured times, and SHE at 1 hour and 6 hours were significantly higher in the pECMO group. There was no significant difference in the levels of brain injury biomarkers between cECMO and pECMO groups. CONCLUSIONS: The hemodynamic data showed that pECMO was superior to cECMO. Based on the biomarker data, neither pECMO nor cECMO for 6 hours caused evidence of brain injury.

Comparison of in vivo antibacterial and antithrombotic activities of two types of pulmonary artery catheters in pig.

BACKGROUND: During pulmonary artery catheter (PAC) implantation, inaccurate measurements of hemodynamic parameters due to infection or thrombosis of PAC can result in severe complications. METHOD: In order to develop a new PAC material, we evaluated the antibacterial and antithrombotic activities of the two types of PAC (Swan Ganz catheter and prototype catheter) in 14 pigs. RESULTS: In the 3-day group, bacterial infection rate was not different between the two types of PAC. In the 7-day group, bacterial infection rate of the prototype catheter was twice as elevated as that of the Swan-Ganz catheter. In the 3-day group, thrombus formation rate of the prototype catheter was twice as elevated as that of the Swan-Ganz catheter. In the 7-day group, thrombus formation rate was the same for the two types of PAC. CONCLUSION: Here, we report an experimental pig model that confirms differences in antibacterial and antithrombotic activities.

A non-randomized retrospective observational study on the subcutaneous esophageal reconstruction after esophagectomy: is it feasible in high-risk patients?

BACKGROUND: Esophageal reconstruction after esophagectomy is a complex procedure with high morbidity and mortality. Anastomotic leakage is more severe and frequent in patients with preoperative comorbidities and may present with septic conditions. Considering the possibility of an easier management of such cases, we evaluated the safety and feasibility of subcutaneous esophageal reconstruction in patients with high operative risks. METHODS: We performed a non-randomized retrospective observational study on the 75 (subcutaneous: 21, intrathoracic: 54) esophageal cancer patients who underwent esophageal reconstruction either through subcutaneous or intrathoracic route between January 2003 and February 2015. Preoperative data including the estimated reasons for the selection of the subcutaneous route were obtained from medical charts. Clinical outcomes were evaluated and compared between the two groups. RESULTS: The mean postoperative hospital stay was longer in the subcutaneous group than the overall group. Anastomotic leakage occurred more frequently in the subcutaneous group [10 (47.6%) vs. 7 (13%), P=0.004]. Three major leakages resulted in chronic cutaneous fistula, but were successfully treated by lower neck reconstruction using radial forearm fasciocutaneous free flap (RFFF). There was no in-hospital mortality in the subcutaneous group. CONCLUSIONS: Subcutaneous esophageal reconstruction in high-risk patients showed a higher rate of anastomotic leakage. However, easier correction without fatal septic conditions could be obtained by primary repair or flap reconstruction resulting in lower perioperative mortality. Therefore, esophageal reconstruction through the subcutaneous route is not recommended as a routine primary option. However, in highly selected patients with unfavorable preoperative comorbidities or intraoperative findings, especially those with poor blood supply to the graft, graft hematoma or edema, or gross tumor invasion to surrounding tissues, esophageal reconstruction through the subcutaneous route may carefully be considered as an alternative to the conventional surgical techniques.

Simulated Microgravity Effects on Nonsmall Cell Lung Cancer Cell Proliferation and Migration.

BACKGROUND: Despite improvements in medical technology, lung cancer metastasis remains a global health problem. The effects of microgravity on cell morphology, structure, functions, and their mechanisms have been widely studied; however, the biological effects of simulated microgravity on the interaction between cells and its eventual influence on the characteristics of cancer cells are yet to be discovered. We examined the effects of simulated microgravity on the metastatic ability of different lung cancer cells using a random positioning machine. METHODS: Human lung cancer cell lines of adenocarcinoma (A549) and squamous cell carcinoma (H1703) were cultured in a 3D clinostat system which was continuously rotated at 5 rpm for 36 h. The experimental and control group were cultured under identical conditions with the exception of clinorotation. RESULTS: Simulated microgravity had different effects on each lung cancer cell line. In A549 cells, the proliferation rate of the clinostat group (2.267 ± 0.010) after exposure to microgravity did not differ from that of the control group (2.271 ± 0.020). However, in H1703 cells, the proliferation rates of the clinostat group (0.534 ± 0.021) was lower than that of the control group (1.082 ± 0.021). The migratory ability of both A549 [remnant cell-free area: 33% (clinostat) vs. 78% (control)] and H1703 cells [40% (clinostat) vs. 68% (control)] were increased after exposure to microgravity. The results of the molecular changes in biomarkers after exposure to microgravity are preliminary. DISCUSSION: Simulated microgravity had different effects on the proliferation and migration of different lung cancer cell lines.Chung JH, Ahn CB, Son KH, Yi E, Son HS, Kim H-S, Lee SH. Simulated microgravity effects on nonsmall cell lung cancer cell proliferation and migration. Aerosp Med Hum Perform. 2017; 88(2):82-89.

The Effect of Pulsatile Versus Nonpulsatile Blood Flow on Viscoelasticity and Red Blood Cell Aggregation in Extracorporeal Circulation.

BACKGROUND: Extracorporeal circulation (ECC) can induce alterations in blood viscoelasticity and cause red blood cell (RBC) aggregation. In this study, the authors evaluated the effects of pump flow pulsatility on blood viscoelasticity and RBC aggregation. METHODS: Mongrel dogs were randomly assigned to two groups: a nonpulsatile pump group (n=6) or a pulsatile pump group (n=6). After ECC was started at a pump flow rate of 80 mL/kg/min, cardiac fibrillation was induced. Blood sampling was performed before and at 1, 2, and 3 hours after ECC commencement. To eliminate bias induced by hematocrit and plasma, all blood samples were adjusted to a hematocrit of 45% using baseline plasma. Blood viscoelasticity, plasma viscosity, hematocrit, arterial blood gas analysis, central venous O2 saturation, and lactate were measured. RESULTS: The blood viscosity and aggregation index decreased abruptly 1 hour after ECC and then remained low during ECC in both groups, but blood elasticity did not change during ECC. Blood viscosity, blood elasticity, plasma viscosity, and the aggregation index were not significantly different in the groups at any time. Hematocrit decreased abruptly 1 hour after ECC in both groups due to dilution by the priming solution used. CONCLUSION: After ECC, blood viscoelasticity and RBC aggregation were not different in the pulsatile and nonpulsatile groups in the adult dog model. Furthermore, pulsatile flow did not have a more harmful effect on blood viscoelasticity or RBC aggregation than nonpulsatile flow.

Evaluation of fluid warmer safety using hemorheologic analysis with outdated human blood.

PURPOSE: A newly developed fluid warmer (ThermoSens®) has a direct blood warming plate, which can result in hemolysis or red blood cell injury during heating. Therefore, to evaluate the safety of heating blood products with a fluid warmer, we conducted laboratory tests to study hemolysis and erythrocyte rheology. METHODS: We used outdated human blood taken from a Korean blood bank. Packed red blood cells mixed with 100 mL isotonic saline was passed through the fluid warmer. Blood flow was achieved by either gravity or 300 mmHg pressure. Blood samples were analyzed before and after heating for hemolysis marker and erythrocyte rheology parameters. RESULTS: The temperatures at the outlet were higher than 38°C at gravity and 300 mmHg pressure, respectively. There were no significant differences in hemolysis markers (hemoglobin, hematocrit, lactate dehydrogenase, and plasma free hemoglobin) or erythrocyte rheology (deformability, disaggregating shear stress, and aggregation index) between before and after heating (p >  0.05) except LDH at gravity (p = 0.0001). CONCLUSION: The ThermoSens® fluid warmer caused no erythrocyte injury or negative effects on rheology during heating. Regarding medical device development, hemorheologic analysis can be useful for safety evaluation of medical devices that directly contact blood for temperature modulation.