Use of current automatic smoke evacuation system in flexible gastrointestinal endoscopy: Its feasibility and potential usefulness.

Objectives: Flexible endoscopy does not have a system that can automatically evacuate surgical smoke generated in the gastrointestinal lumen. We aimed to investigate the feasibility and potential usefulness of automatic smoke evacuation systems in flexible endoscopy. Methods: [Bench] After surgical smoke generated in the stomach was evacuated by the evacuator, the degree of residual smoke and gastric luminal collapse were evaluated to optimize the evacuator settings. [Animal] Insufflation, suction, and total operation time to complete the protocol of 10 cauterizations of the gastric mucosa were measured in three groups: "manual suction only," "manual suction with automatic evacuation (50% force)," and "manual suction with automatic evacuation (70% force)." The stability of endoscopic visualization and operability was evaluated by 10 endoscopists blinded to those suction settings, and the number of manual suctions, insufflations, and total operation time were measured. Results: [Bench] The degree of residual smoke and gastric luminal collapse were inversely correlated. [Animal] When the automatic evacuator was partially used, there was no difference in the insufflation time, but the suction time (vs 50%; p = 0.011, vs. 70%; p = 0.011) and total operation time (vs. 50%; p = 0.012, vs. 70%; p = 0.036) were significantly reduced compared to manual operation only. Furthermore, manual suction with automatic evacuation (50% force) significantly improved the stability of endoscopic visualization and operability compared to manual operation only (p = 0.041, p = 0.0085). Conclusions: The automatic smoke evacuation in flexible gastrointestinal endoscopy was potentially feasible and useful by improving the device setting.

Application of a laparoscopic device for cell-derived sheet transplantation on the liver in a porcine model.

BACKGROUND: Cell-derived sheets are of global interest for regenerative therapy. Transplanting a sheet for abdominal organs requires a device for laparoscopic delivery to minimize invasiveness. Here, using a porcine model, we aimed to confirm the feasibility of a device developed to deliver sheets to the thoracic cavity in a laparoscopic transplantation procedure. MATERIAL AND METHODS: We used the device to transplant human skeletal myoblast cell sheets onto the liver and measured extra-corporeal, intra-abdominal, and total procedure times for sheet transplantation. Tissues, including the liver and the sheet, were collected two days after transplantation and analyzed histologically. RESULTS: In all experiments (n = 27), all sheets were successfully placed at target locations. The mean (± standard deviation) extra-corporeal, intra-abdominal, and total procedure times were 44 ± 29, 33 ± 12, and 77 ± 36 s, respectively. We found no difference between the two surgeons in procedure times. Histological analyses showed no liver damage with the transplantation and that sheets were transplanted closely onto the liver tissue without gaps. CONCLUSION: We confirmed the feasibility of a simple universal device to transplant cell-derived sheets via laparoscopic surgery. This device could support a minimally invasive procedure for sheet transplantation.

Clinical effectiveness of a new scope warmer/cleaner for laparoscopic and thoracoscopic surgery.

In laparoscopic and thoracoscopic surgery, maintaining clear visualization is crucial for safe and efficient operation. We have developed a new scope warmer/cleaner (Lapahot®) based on "hot-pack" technology. We used our device in 20 consecutive laparoscopic and thoracoscopic cases and compared it with the conventional warm saline method. Lens fogging was not observed in any of the cases, and the cleaning function was comparable to the warm saline method. Moreover, continuous temperature monitoring showed that Lapahot® maintained its temperature much longer than warm saline. Our novel device has the potential to become the new standard for lens defogging and cleaning.

The role of anterior gastropexy in elderly Japanese hiatal hernia patients.

PURPOSE: As Japanese society ages, the number of surgeries performed in elderly patients with hiatal hernia (HH) is increasing. In this study, we examined the feasibility, safety, and potential effectiveness of the addition of anterior gastropexy to hiatoplasty with or without mesh repair and/or fundoplication in elderly Japanese HH patients. METHODS: We retrospectively evaluated 39 patients who underwent laparoscopic HH repair between 2010 and 2021. We divided them into 2 groups according to age: the "younger" group (< 75 years old, n = 21), and the "older" group (≥ 75 years old, n = 18). The patient characteristics, intraoperative data, and postoperative results were collected. RESULTS: The median ages were 68 and 82 years old in the younger and older groups, respectively, and the female ratio was similar between the groups (younger vs. older: 67% vs. 78%, p = 0.44). The older group had more type III/IV HH cases than the younger group (19% vs. 83%, p < 0.001). The operation time was longer in the older group than in the younger group, but there was no significant difference in blood loss, perioperative complications, or postoperative length of stay between the groups. The older group had significantly more cases of anterior gastropexy (0% vs. 78%, p < 0.001) and less fundoplication (100% vs. 67%, p = 0.004) than the younger group. There was no significant difference in HH recurrence between the groups (5% vs. 11%, p = 0.46). CONCLUSIONS: The addition of anterior gastropexy to other procedures is feasible, safe, and potentially effective in elderly Japanese patients with HH.

Swelling behavior of calcium ion-crosslinked sodium alginate in an in vitro hemostatic tamponade model.

Various types of hemostatic agents are used to manage bleeding in surgery. Many such agents are animal products, which carry the risk of secondary infection. The aim of this study is to develop a novel hemostatic agent from a non-animal source that quickly stops bleeding, is easy to use, and has no risk of infection. In this study, we synthesized calcium ion-crosslinked sodium alginate (Alg-Na/Ca) by partial substitution of Ca ions for Na ions in sodium alginate. We prepared 12 kinds of Alg-Na/Ca powders with different Ca mass ratios, molecular weights, M/G ratios and particle size distributions and measured their swelling ratio and the burst pressure generated. We found that Alg-Na/Ca began to swell immediately after contact with saline, especially Alg-Na/Ca at Ca mass ratios of 74.1-77.0 % showed a high swelling ratio after 2 min and a high burst pressure, over 200 % and 500 mmHg respectively. Also, there is a correlation between the swelling ratio after 2 min and the burst pressure. Our results suggest that, by optimizing the composition conditions, Alg-Na/Ca may be an effective hemostatic agent that could act as a tamponade by absorbing and swelling at a bleeding site to quickly achieve primary hemostasis.

Innovative device for surgical wound irrigation: a preclinical testing and pilot clinical validation study.

INTRODUCTION: Surgical site infection (SSI) poses a substantial postoperative challenge, affecting patient recovery and healthcare costs. While surgical wound irrigation is pivotal in SSI reduction, consensus on the optimal method remains elusive. We developed a novel device for surgical wound irrigation and conducted preclinical and clinical evaluations to evaluate its efficacy and safety. METHODS: Two preclinical experiments using swine were performed. In the washability test, two contaminated wound model were established, and the cleansing rate between the device and the conventional method were compared. In the contamination test, the irrigation procedure with a fluorescent solution assessed the surrounding contamination of drapes. Subsequently, a clinical trial involving patients undergoing abdominal surgery was conducted. RESULTS: The washability test demonstrated significantly higher cleansing rates with the device method (86.4% and 82.5%) compared to the conventional method (65.2% and 65.1%) in two contamination models. The contamination test revealed a smaller contaminated region with the device method than the conventional method. In the clinical trial involving 17 abdominal surgery cases, no superficial SSIs or adverse events related to device use were observed. CONCLUSIONS: Our newly developed device exhibits potential for achieving more effective and safe SSI control compared to conventional wound irrigation.

Association between fibrosis around the tumor and postoperative infectious complication in patients with esophageal cancer who underwent preoperative therapy.

BACKGROUND: Multidisciplinary treatment combining chemotherapy, chemo radiation therapy (CRT), and surgery has been utilized for advanced esophageal cancer. However, preoperative treatment could cause postoperative inflammation and complications. We hypothesized that fibrosis surrounding tumor tissue caused by preoperative treatment could induce postoperative systemic inflammation and influence postoperative complications. METHODS: Surgical specimens from patients with thoracic esophageal cancer who underwent preoperative CRT (38 cases) or chemotherapy (77 cases) and those who received no preoperative treatment (49 cases) were evaluated to measure the fibrotic area adjacent to the tumor (10 mm from the tumor edge) by applying Azan staining. Pleural effusion and peripheral blood serum interleukin-6 levels were analyzed to evaluate local and systemic postoperative inflammation in 37 patients. RESULTS: The fibrotic areas around the tumors were significantly larger in patients who underwent preoperative CRT than in patients who underwent chemotherapy (p < 0.001) or who had received no preoperative therapy (p < 0.001). Infectious complications were higher in patients who underwent preoperative CRT than chemotherapy (p = 0.047) or surgery alone (p < 0.001). The patients with larger fibrotic areas had more infectious complications (p = 0.028). Multivariate analysis showed that both a large fibrotic area and preoperative CRT were correlated with infectious complications, but not significantly. Pleural effusion interleukin-6 was significantly higher in patients who underwent preoperative CRT than in patients who received no preoperative therapy (p = 0.013). CONCLUSIONS: A large fibrotic peritumoral esophageal tissue area after preoperative treatment could cause postoperative inflammatory response and infectious complications.

Long-Term Outcomes of Pylorus-Preserving Gastrectomy for Early Gastric Cancer.

BACKGROUND: In the short term, pylorus-preserving gastrectomy (PPG) has been reported to have advantages over distal gastrectomy (DG) with regard to postprandial symptoms and dumping syndrome. We aimed to evaluate the quality of life after PPG for early gastric cancer in the long term in comparison to that after DG. METHODS: Twenty-six patients who underwent gastrectomy (11 PPG, 15 DG) for early gastric cancer at Osaka University Hospital participated and were followed for more than 4 years. Body weight changes, nutritional status, dual-phase scintigraphy findings, endoscopic survey results, and questionnaire responses after gastrectomy were examined. RESULTS: There were significantly lower ratios of weight changes in PPG than in DG, 5 years after surgery. There were no differences in the clinicopathological characteristics, nutritional parameters, questionnaire responses, and endoscopic findings between the two groups. Based on gastric scintigraphy, although the gastric emptying of liquids showed similar curves in the two groups, gastric emptying of solids was significantly slower in the PPG group than in the DG group (P = .039). DISCUSSION: PPG had advantages with regard to long-term outcomes over DG in terms of weight maintenance and the prevention of rapid gastric emptying. PPG might be efficient in patients with early gastric cancer.

Indications for neoadjuvant chemotherapy in older patients undergoing esophagectomy for esophageal cancer.

PURPOSE: To investigate the indications for neoadjuvant chemotherapy (NAC) in esophageal cancer patients aged 75 years or older. METHODS: We analyzed data, retrospectively, from 155 patients over 75 years old, who underwent esophagectomy for esophageal cancer between 2010 and 2020. Forty-one patients underwent upfront surgery (US group) and 114 were treated with NAC followed by surgery (NAC group). We compared the patient backgrounds and perioperative outcomes including prognosis, between the two groups. RESULTS: The NAC group patients were significantly younger and had significantly more advanced clinical stage disease than the US group patients. The incidence of postoperative complications was similar in the two groups. Patients with a good pathological response to NAC had a significantly better prognosis than those with a poor response and those in the US group. Among patients with a performance status (PS) of 0, the 5-year OS rate was 56.5% in the NAC group and 38.1% in the US group (HR = 0.63, 95% CI 0.35-1.12). Among those with a PS of 1-2, the 5-year OS rates were 28.1% and 57.1%, respectively (HR = 1.69, 95% CI 0.99-2.89; P = 0.037 for interaction). CONCLUSIONS: NAC did not improve the postoperative prognosis of older esophageal cancer patients with a PS of 1 or higher.

A new scope warmer/cleaner for laparoscopic surgery: a disposable hot pack.

BACKGROUND: Fogging and staining of a laparoscope lens negatively impact surgical visualization. We hypothesized that the disposable hot pack could not only warm but also clean laparoscopes. Hence, this study verified and developed the disposable hot pack with anti-fogging and cleaning function. MATERIAL AND METHODS: The laparoscope was inserted into a swine abdominal cavity for five minutes. Then, the laparoscopic tip was heated with 65 °C saline or the folded disposable hot pack with nonwoven fabric coated surfactant for ten seconds (n = 15). Also, a laparoscopic tip with dirt was wiped with the prototype or conventional gauze for 10 s (n = 10). The dirt, fogging, and temperature of the laparoscopic tip were respectively evaluated after the laparoscope was inserted into the abdominal cavity. RESULTS: The laparoscopic tip temperature five minutes after insertion into the abdominal cavity was similar (31.1 °C vs 31.2 °C, p = 0.748) and there was no fogging in both methods. The conventional gauze had significantly less temperature of the laparoscopic tip after cleaning and higher fogging occurrence than the prototype (29.5 °C vs 34.0 °C, p < 0.001, 30% vs 0%, p = 0.030, respectively), although there was no dirt left after both methods. CONCLUSION: The disposable hot pack has a strong potential as an anti-fogging and cleaning device for use during laparoscopic surgery.

An international Delphi consensus for surgical quality assessment of lymphadenectomy and anastomosis in minimally invasive total gastrectomy for gastric cancer.

BACKGROUND: Minimally invasive total gastrectomy (MITG) is a mainstay for curative treatment of patients with gastric cancer. To define and standardize optimal surgical techniques and further improve clinical outcomes through the enhanced MITG surgical quality, there must be consensus on the key technical steps of lymphadenectomy and anastomosis creation, which is currently lacking. This study aimed to determine an expert consensus from an international panel regarding the technical aspects of the performance of MITG for oncological indications using the Delphi method. METHODS: A 100-point scoping survey was created based on the deconstruction of MITG into its key technical steps through local and international expert opinion and literature evidence. An international expert panel comprising upper gastrointestinal and general surgeons participated in multiple rounds of a Delphi consensus. The panelists voted on the issues concerning importance, difficulty, or agreement using an online questionnaire. A priori consensus standard was set at > 80% for agreement to a statement. Internal consistency and reliability were evaluated using Cronbach's α. RESULTS: Thirty expert upper gastrointestinal and general surgeons participated in three online Delphi rounds, generating a final consensus of 41 statements regarding MITG for gastric cancer. The consensus was gained from 22, 12, and 7 questions from Delphi rounds 1, 2, and 3, which were rephrased into the 41 statetments respectively. For lymphadenectomy and aspects of anastomosis creation, Cronbach's α for round 1 was 0.896 and 0.886, and for round 2 was 0.848 and 0.779, regarding difficulty or importance. CONCLUSIONS: The Delphi consensus defined 41 steps as crucial for performing a high-quality MITG for oncological indications based on the standards of an international panel. The results of this consensus provide a platform for creating and validating surgical quality assessment tools designed to improve clinical outcomes and standardize surgical quality in MITG.

Laparoscopic repair of a traumatic diaphragmatic hernia with repeated colon incarcerations 7 years after injury: a case report.

BACKGROUND: A diaphragmatic hernia is a prolapse of the abdominal organs into the thoracic cavity through a hole in the diaphragm. Traumatic diaphragmatic injuries are rare and usually occur after blunt or penetrating thoracic or abdominal traumas. Blunt diaphragmatic rupture rarely accounts for immediate mortality and may go clinically silent until complications occur which can be life threatening. It usually present late with intrathoracic herniation of abdominal viscera and carry a high mortality rate. We experienced a very rare case who showed repeated colon incarcerations 7 years after injury. And, we operated laparoscopically. CASE PRESENTATION: A 64-year-old man presented with multiple left rib fractures that occurred during an accident. After 7 years, he visited the emergency department with the chief complaint of left shoulder pain and epicardial pain after eating. He was diagnosed with transverse colon incarceration due to a left diaphragmatic hernia by computed tomography (CT) and X-ray imaging. Surgical repair was recommended, but he refused as the symptoms improved. Fourteen months later, the patient revisited the hospital in similar symptoms and improved spontaneously. He consulted our hospital for the surgical indication. We recommended that he undergo surgery, showing images of the X-ray and CT when his transverse colon was obstructed and he felt pain and when symptoms improved. Finally, he decided to undergo surgery. We performed diaphragmatic hernia repair with laparoscopic direct suturing in good view. The patient experienced an uneventful postoperative recovery period. The absence of diaphragmatic herniation recurrence was confirmed seven months after surgery. CONCLUSIONS: We experienced a traumatic diaphragmatic hernia with repeated colon incarcerations 7 years after injury and performed surgical repair laparoscopically.

Potential role of a novel endoscopic retrieval bag for large colorectal resected specimen: a proof-of-concept study.

Endoscopic submucosal dissection enables en bloc resection of large superficial colorectal neoplasms. However, it is sometimes challenging to retrieve a large resected specimen via the anus without sample fragmentation. A novel "bag-type" retrieval device has been developed to accomplish complete isolation and non-destructive delivery of oversized specimens. This single-center retrospective study was performed to demonstrate the efficacy of this device for large colorectal resected specimens. Among 17 patients, we identified 18 superficial colorectal lesions for which the use of a novel retrieval device (Endo Carry Large Type) was indicated at specimen delivery at a referral cancer institute from March 2021 to July 2022. The median (interquartile range) tumor size was 62.5 (52.0-79.5) mm. Retrieval of 17 (94%) of 18 resected specimens was performed using the Endo Carry Large Type, and 16 (89%) were successfully retrieved without sample fragmentation. The median (interquartile range) retrieval time was 4 (4-8) minutes, and no apparent adverse events were observed. The novel Endo Carry Large Type device can accomplish colorectal specimen retrieval safely and quickly without specimen damage and therefore may contribute to accurate pathological diagnosis.

A case of Barrett's esophageal adenocarcinoma and severe scoliosis with successful salvage esophagectomy after definitive chemoradiotherapy.

BACKGROUND: Severe scoliosis can cause reflux esophagitis, and is a risk factor for Barrett's adenocarcinoma of the esophagus. Severe scoliosis is associated with respiratory dysfunction, impaired operative tolerance, and anatomical difficulty in surgical manipulation, and is, therefore, considered a high surgical risk. In this report, we describe the case of a young patient with Barrett's esophageal adenocarcinoma with severe scoliosis who underwent salvage surgery after radical chemoradiotherapy. CASE PRESENTATION: The patient was a 39-year-old male. Although he had severe scoliosis and paraplegia of both lower limbs since childhood, he was independent in activities of daily living. His previous doctor, who diagnosed the esophageal cancer, determined that surgery was not indicated due to the coexistence of severe scoliosis, so he underwent chemoradiotherapy with curative intent. After chemoradiotherapy, the patient was referred to our hospital for a second opinion because of a tumor remnant. After various additional examinations, thoracoscopic and laparoscopic subtotal esophagectomy for esophageal cancer was performed, along with ante-thoracic route reconstruction using a narrow gastric tube. Although the patient had symptoms associated with postoperative reflux, he recovered well overall and was discharged home about 4 weeks after surgery. CONCLUSIONS: We report the case of an esophageal cancer patient with severe scoliosis at high surgical risk who underwent successful minimally invasive esophagectomy.

Association between circ_0004365 and cisplatin resistance in esophageal squamous cell carcinoma.

Cisplatin is one of the most predominant drugs for the chemotherapy of esophageal squamous cell carcinoma (ESCC); however, the underlying resistance mechanisms are still almost unknown. The present study performed RNA sequencing of human circular RNA (circRNA) in TE11 cells and cisplatin-resistant TE11 cells (TE11R). The expression profiles determined using CIRCexplorer2 revealed that the expression of circ_0004365, mapped on the Semaphorin 3C gene, was significantly greater in TE11R compared with in TE11. In reverse transcription-quantitative PCR, circ_0004365 expression was observed in human ESCC and non-tumor tissues and was significantly upregulated in ESCC tumor tissues after chemotherapy. Circ_0004365 expression was significantly upregulated in patients with poor pathological response (P=0.02). Furthermore, patients with advanced pT stage showed an upregulation in circ_0004365 expression after chemotherapy (P=0.02). The MTT assay revealed that knockdown of circ_0003465 in TE11 significantly decreased resistance to cisplatin. In conclusion, the present study suggested that circ_0004365 was associated with cisplatin resistance in ESCC and can be used as both a novel biomarker and a therapeutic target.

Oral frailty is a risk factor for body weight loss after gastrectomy: a single-center, retrospective study.

BACKGROUND: Body weight loss (BWL) is a serious complication of gastrectomy in patients with gastric cancer (GC). Nutritional intervention alone is inadequate for preventing BWL, and a new approach is needed. Oral frailty among older adults has recently attracted attention. This study aimed to investigate masticatory ability and BWL after gastrectomy. METHODS: This was a single-center, retrospective study. Functional tooth units (FTU) were used to measure masticatory ability. Patients with FTU < 4 were defined as low FTU group and FTU ≥ 4 as high FTU group. The BWL was compared between the two groups. RESULTS: Sixty patients who underwent distal gastrectomy for GC from March 2022 to January 2023 were enrolled in this study. The median FTU was 3 (range 0-12). The low-FTU group (FTU < 4) included 29 patients, while the high-FTU group (FTU ≥ 4) included 31 patients. The %BWL in the low FTU group was significantly higher than that in the high-FTU group at 1 and 3 months (p = 0.003 and p = 0.017, respectively). The risk factors associated with a %BWL > 5 at 1 and 3 months after gastrectomy were analyzed using logistic regression analysis. Only FTU < 4 was an independent risk factor after gastrectomy for GC in univariate and multivariate analyses (p = 0.028 and p = 0.006, respectively). CONCLUSIONS: Low FTU in patients with preoperative GC was a risk factor for %BWL 1 and 3 months postoperatively. Appropriate oral interventions may be useful in improving the postoperative nutritional status after gastrectomy.

Efficacy of human resource development program for young industry personnel who will be involved in future medical device development.

BACKGROUND: Training next-generation personnel from small/medium enterprises (SMEs) is an urgent issue in promoting medical device research and development (R&D). Since 2014 we have engaged in governmentally funded human resource development program for medical/non-medical SMEs, and have assessed its effectiveness by analyzing self-evaluation of achievement level (SEAL) data obtained before and after the training course. METHODS: Human resource development experts interviewed 34 key opinion leaders with deep knowledge of medical device R&D from industry, government, and academia. The skills required for R&D personnel were written down, and a set of skills was created by making a greatest common measure in the list of common elements among them. Using that skill sets, skill evaluations were conducted on trainees at "Osaka University Training Course," twice before participation and after completion of the entire program using SEAL assessment. RESULTS: There were 97 men and 25 women, with one-third in the'30 s. Among them, 61 participants (50%) were from R&D divisions, and 32 (26%) were from business/sales divisions. 94 (77%) were from medical SMEs, and 28 (23%) were from non-medical SMEs (new entry). After completing the training course, significant growth was observed in every item of both Soft and Hard skill sets. Especially in new entry SME members, a striking improvement was observed in practical medical knowledge to enhance communication with medical doctors (p < 0.0001). CONCLUSION: Our training course, though 7-day-short in total, showed that both Soft and Hard skills could be improved in young medical/non-medical SME members. Further assessment is needed to establish the necessary skill sets for our future partners from industries, to foster the creation of innovative medical devices through med-tech collaboration.

Surgery for multiple gastric gastrointestinal stromal tumors and large esophageal diverticulum related to germline mutation of the KIT gene: a case report.

BACKGROUND: Familial gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the digestive tract caused by germline gain-of-function mutations in the KIT gene or platelet-derived growth factor receptor alpha gene (PDGFRA). These mutations cause not only multiple GISTs but also diffuse hyperplasia of interstitial cells of Cajal (ICCs), which is related to esophageal motility disorder. CASE PRESENTATION: A 53-year-old man was referred to our hospital because of anemia and dysphagia. Fifteen years earlier, he had undergone a laparoscopic partial gastrectomy for multiple gastric GISTs with a germline mutation in exon 17 of the KIT gene. An upper gastrointestinal endoscopy revealed that the patient had multiple gastric GISTs and a large esophageal diverticulum directly above the esophagogastric junction. The largest gastric tumor was 7 cm, with a delle that might cause bleeding. Because the patient presented with dysphagia, we performed video-assisted thoracic esophagectomy and laparoscopic-assisted proximal gastrectomy simultaneously. The patient had survived without metastasis for 4 years after surgery and dysphagia had improved. CONCLUSIONS: This is the first report of successful laparoscopic-thoracoscopic surgery for a patient with familial gastric GISTs accompanied with a large esophageal diverticulum.

Randomized controlled trial of new hemostatic material "sodium calcium alginate" in a preclinical model.

BACKGROUND: The demand for nonbiological hemostatic materials has increased in surgical practice; however, few have sufficient hemostatic efficacy. This study investigated whether optimizing the composition of sodium calcium alginate, which forms a stable gel, improves hemostatic efficacy. METHODS: The sodium calcium alginate was changed for each composition, including powder size, calcium substitution rate, molecular weight, and mannuronic/guluronic acid ratio. The hemostasis in liver punch-out injury and bleeding was evaluated using swine. For the study, sodium calcium alginate with different compositions was randomly applied to bleeding sites. Previous hemostatic materials, including cellulose and sodium alginate, were used as a control. We investigated hemostasis at 2 and 5 minutes after application. RESULTS: Each powder size (53-150 µm, 150-250 µm, 53-250 µm) had a similar hemostatic effect. However, the hemostatic rate was significantly higher in sodium calcium alginate than in previous hemostatic materials (P value < .01). A 74.1% calcium substitution rate had the highest hemostasis at 2 and 5 minutes after application (2 minutes: 100%, 5 minutes: 95.2%). Regarding molecular weight, the hemostatic rate was significantly higher in 333,000 than in 50,000 (2 minutes: 95% vs 70%, 5 minutes: 95% vs 70%, P = .038). Moreover, a 1.9 mannuronic/guluronic acid ratio had the highest hemostasis compared with the 0.4 mannuronic/guluronic acid ratio (2 minutes: 58.8% vs 11.8%, 5 minutes: 58.8% vs 0%, P = .033) CONCLUSION: The composition of sodium calcium alginate with a high hemostatic effect was optimized. This new hemostatic material demonstrated potential usefulness for bleeding during surgery.