Task difficulty, risk feeling, and safety margin in the determination of driver behavior to prepare for traffic conflicts.

Unpredictable pedestrian and cyclist behavior associated with their appearance on the road in blind spots contributes to traffic near-misses or crashes. When experienced drivers are confronted with uncertainty, they take defensive measures called hazard-anticipatory driving, such as decreasing the vehicle velocity and/or increasing the lateral distance. Our research sought to understand the motivational determinants and perceptual processes that determine driver behavior in preparation for traffic conflicts with covert hazards. This study aimed to investigate the influence of driving experience on drivers' perceptions and behaviors to prepare for traffic conflicts. Two experiments were designed with 8 experienced and 13 inexperienced participants. In Experiment 1, participants were asked to provide their subjective impressions of task difficulty, feeling of risk, and statistical risk pertaining to assess their perceptions of the separation between task demand and capability after viewing animation clips of road scenes with blind intersections under different forced speeds. In Experiment 2, participants drove using a driving simulator in scenes with blind intersections, similar to those in Experiment 1. We sought to explore the motivational determinants of behavior regarding the relationship between subjective feelings and objective safety margins. The results showed that the driver's perception of task difficulty correlated with their driving speed, and inexperienced participants tended to underestimate task difficulty compared to experienced participants. The task difficulty and the feeling of risk were strongly correlated regardless of experience, and estimation of statistical risk differed depending on experience. The subjective task difficulty (and/or risk feeling) and objective safety margin were strongly correlated for experienced participants. Experienced participants who perceived a higher degree of difficulty in the forced-paced driving task tended to have greater safety margins in the self-paced driving task. These findings suggest that experienced participants with individually tolerable safety margins adjust their driving velocity and/or lateral distance in the control of task difficulty (and/or risk feeling) to prepare for traffic conflicts. Therefore, the underestimation of task difficulty should be considered when designing effective measures, such as driver assistance systems, to guide inexperienced drivers toward normative behaviors.

Decreased numbers of gastric, colorectal, lung, and breast cancer surgeries performed in 17 cancer-designated hospitals in Gunma Prefecture of Japan during the COVID-19 pandemic.

PURPOSE: This study aims to clarify the influence of the COVID-19 pandemic on cancer surgery in Gunma Prefecture. METHODS: A total of 9839 cases (1406 gastric cancer, 3569 colorectal cancer, 1614 lung cancer, and 3250 breast cancer) from 17 hospitals in Gunma Prefecture were investigated. We compared the number of surgical cases, proportion of cases found by screening, and cStage at the time of the first visit by month in 2020 and 2021 with those in 2019. RESULTS: The rate of decline in cancer surgery was 8.9% in 2020 compared with 2019 (p = 0.0052). Compared with the same month of 2019, in some months of 2020 and 2021, significant decreases were observed in the number of surgeries for gastric and colorectal cancer, the percentage of surgical cases detected by screening in all four cancers, and the proportion of cancers with a relatively early cStage in gastric and breast cancer. CONCLUSIONS: The number of surgical cases of the four cancer types detected by cancer screening decreased in Gunma Prefecture owing to the influence of the COVID-19 pandemic. Furthermore, for some cancer types, the number of operations performed in patients with early-stage cancer is also decreased.

Effects of gender, age, experience, and practice on driver reaction and acceptance of traffic jam chauffeur systems.

This study conducted a driving simulation experiment to compare four automated driving systems (ADS) designs during lane change demanding traffic situations on highways while accounting for the drivers' gender, age, experience, and practice. A lane-change maneuver was required when the automated vehicle approaches traffic congestion on the left-hand lane. ADS-1 can only reduce the speed to synchronize with the congestion. ADS-2 reduces the speed and issues an optional request to intervene, advising the driver to change lanes manually. ADS-3 offers to overtake the congestion autonomously if the driver approves it. ADS-4 overtakes the congestion autonomously without the driver's approval. Results of drivers' reaction, acceptance, and trust indicated that differences between ADS designs increase when considering the combined effect of drivers' demographic factors more than the individual effect of each factor. However, the more ADS seems to have driver-like capacities, the more impact of demographic factors is expected. While preliminary, these findings may help us understand how ADS users' behavior can differ based on the interaction between human demographic factors and system design.

Long-term survival of two patients with pancreatic cancer after resection of liver and lung oligometastases: a case report.

BACKGROUND: The efficacy of resection of pancreatic cancer metastases has not been established. We here report two patients with long-term survival after resection of lung and liver metastases. CASE PRESENTATION: The first patient underwent distal pancreatectomy for pancreatic cancer. One year later, she underwent partial hepatectomy for a single liver metastasis. She subsequently underwent pulmonary resections 7, 7.5, 9, and 10 years later for pulmonary metastases from pancreatic cancer. Thus, this patient underwent five surgeries for metastases, one for a liver metastasis and four for lung metastases. All of the tumors were pathologically diagnosed as metastatic pancreatic cancer. She is currently alive without new recurrence 10 years after the initial diagnosis. The second patient underwent pancreaticoduodenectomy for pancreatic cancer. Four years later, she underwent a thoracoscopic partial resection for lung metastasis. The tumor was similar to the pancreatic cancer on pathological examination. She is currently alive without new recurrences 6 years after the initial diagnosis. CONCLUSION: Long-term survival can be achieved in some patients with pancreatic cancer by resection of metachronous liver or lung metastases.

Multi-agent traffic simulations to estimate the impact of automated technologies on safety.

Objective: The objective of this article was to develop a multi-agent traffic simulation methodology to estimate the potential road safety improvements of automated vehicle technologies. Methods: We developed a computer program that merges road infrastructure data with a large number of vehicles, drivers, and pedestrians. Human errors are induced by modeling inattention, aimless driving, insufficient safety confirmation, misjudgment, and inadequate operation. The program was applied to simulate traffic in a prescribed area in Tsukuba city. First, a 100% manual driving scenario was set to simulate traffic for a total preset vehicle travel distance. The crashes from this simulation were compared with real-world crash data from the prescribed area from 2012 to 2017. Thereafter, 4 additional scenarios of increasing levels of automation penetration (including combinations of automated emergency braking [AEB], lane departure warning [LDW], and SAE Level 4 functions) were implemented to estimate their impact on safety. Results: Under manual driving, the system simulated a total of 859 crashes including single-car lane departure, car-to-car, and car-to-pedestrian crashes. These crashes tended to occur in locations similar to real-world crashes. The number of crashes predicted decreased to 156 cases with increasing level of automation. All of the technologies considered contributed to the decrease in crashes. Crash reductions attributable to AEB and LDW in the simulations were comparable to those reported in recent field studies. For the highest levels of automation, no assessment data were available and hence the results should be carefully treated. Further, in modeling automated functions, potentially negative aspects such as sensing failure or human overreliance were not incorporated. Conclusions: We developed a multi-agent traffic simulation methodology to estimate the effect of different automated vehicle technologies on safety. The crash locations resulting from simulations of manual driving within a limited area in Japan were preliminary assessed by comparison with real-world crash data collected in the same area. Increasing penetration levels of AEB and LDW led to a large reduction in both the frequency and severity of rear-end crashes, followed by car-to-car head-on crashes and single-vehicle lane departure crashes. Preliminary estimations of the potential safety improvements that may be achieved with highly automated driving technologies were also obtained.

Phase II Study of S-1 plus Trastuzumab for HER2-positive Metastatic Breast Cancer (GBCCSG-01).

AIM: Treatment strategies for patients with human epidermal growth factor 2 (HER2)-positive metastatic breast cancer (MBC) have significantly progressed. The use of trastuzumab, a monoclonal antibody targeting the HER2 (human epidermal growth factor 2) protein, in combination with chemotherapy improves survival in patients with HER2-positive breast cancer. S-1, an oral combination of fluorouracil derivatives, is widely used in Japan and is more convenient than intravenous drugs. However, little is known about the combination of S-1 and trastuzumab in patients with HER2-positive MBC. PATIENTS AND METHODS: We conducted a single-arm, open-label, multicenter prospective phase II study to evaluate the efficacy of an S-1 plus trastuzumab regimen for HER2-positive MBC. S-1 was administered orally [80-120 mg, based on body surface area (BSA)] twice a day for 14 consecutive days in a 3-week cycle. Patients with BSA of <1.25 m2 received a total of 80 mg of S-1, those with BSA ≥1.5 m2 received 120 mg, and the remaining received 100 mg daily in two divided doses. Trastuzumab was administered intravenously at 8 mg/kg on day 1 of the first cycle and at 6 mg/kg on day 1 of subsequent cycles, i.e., every 3 weeks. RESULTS: Between December 2008 and March 2013, 10 patients were enrolled and received a median of 17 (range=3-76) cycles of treatment. Overall response and clinical benefit rates were 60.0% and 90.0%, respectively. Progression-free survival was 15.8 (95% confidence interval=9.4-29.6) months and overall survival was 45.5 (95% confidence interval=37.1-62.2) months. Grade 3/4 adverse events included were neutropenia and hyperglycemia in one patient each (10.0%). There was no clinically significant cardiotoxicity. CONCLUSION: The combination of S-1 and trastuzumab was tolerable and had excellent efficacy with good response and disease control in this study. S-1 plus anti-HER2 therapy is a feasible treatment option for HER2-positive MBC.

Lung adenocarcinoma with anomalous bronchi and pulmonary veins preoperatively identified by computed tomography.

A 69-year-old woman visited our hospital complaining of right chest pain. Chest computed tomography showed a 55 × 45 mm tumor in the right upper lobe. Bronchoscopy revealed displaced anomalous B 1 and B 2+3 arising from the right main bronchus, and the patient was diagnosed with lung adenocarcinoma by transbronchial lung biopsy from the displaced B 2+3 . Three-dimensional computed tomography with multiplanar reconstruction revealed a displaced anomalous B 1 and B 2+3 branching directly from the right main bronchus, respectively, and abnormal distribution of the aberrant pulmonary vein (V 2 ) descended dorsally to the right main bronchus and emptied into the left atrium. Video-assisted right upper lobectomy with nodal dissection was successfully performed. Attention should be paid to the anomalous bronchus and pulmonary vessels for safer lung cancer operations, especially for video-assisted thoracic surgery.

Long-term quality-of-life comparison of total gastrectomy and proximal gastrectomy by postgastrectomy syndrome assessment scale (PGSAS-45): a nationwide multi-institutional study.

BACKGROUND: Although proximal gastrectomy (PG) is widely accepted as a function-preserving operation for early upper-third gastric cancer, postoperative disorders, such as reflux or gastric stasis, have often been pointed out. From the perspective of postoperative disorder, the choice of total gastrectomy (TG) or PG for such cancers is still controversial. By using the newly developed Postgastrectomy Syndrome Assessment Scale (PGSAS)-45, the quality of life after TG and PG was compared. METHODS: The PGSAS-45 consists of 45 items composed of the SF-8 and GSRS scales and 22 new items. The main outcomes are measured by seven subscales (SS) covering symptoms, physical and mental component summary (SF-8), meals (amount and quality), ability to work, dissatisfaction for daily life, and change in body weight. A total of 2,368 eligible questionnaires were acquired from 52 institutions. From these, 393 patients with TG and 193 patients with PG were selected and compared. RESULTS: The PG was better than TG in terms of body weight loss (TG 13.8% vs. PG 10.9%; p = 0.003), necessity for additional meals (2.4 vs. 2.0; p < 0.001), diarrhea SS (2.3 vs. 2.0; p = 0.048), and dumping SS (2.3 vs. 2.0; p = 0.043). There were no differences in the other main outcome measures. CONCLUSIONS: Proximal gastrectomy appears to be valuable as a function-preserving procedure for early upper-third gastric cancer.

A multicenter long-term study of imatinib treatment for Japanese patients with unresectable or recurrent gastrointestinal stromal tumors.

BACKGROUND AND OBJECTIVES: This multicenter study, which was conducted in northern Kanto, Japan, aimed to assess the efficacy of imatinib mesylate against advanced or recurrent gastrointestinal stromal tumors (GIST). METHODS: The clinicopathological data of 234 GIST patients who were treated at one of the 11 participating hospitals from 2001-2011 were retrospectively reviewed. Imatinib was administered as a first-line therapy in cases involving unresectable disease or postoperative recurrence (41 cases). The median follow-up period was 4.0 years. RESULTS: After a median follow-up period of 4.0 years, the patients treated with imatinib (n = 41) exhibited 1-, 3-, and 5-year overall survival (OS) rates of 92.3%, 74.9%, and 53.8%, respectively. In univariate and multivariate analyses, imatinib dose reduction and achieving a complete or partial response were found to be associated with increased OS. CONCLUSIONS: Long-term imatinib treatment is recommended for patients with non-progressive disease. If patients experience significant toxicities, temporary dose reduction might be useful.

Surgical resection of a solitary plasmacytoma originating in a rib.

Plasma cell neoplasms can present as a single lesion (solitary plasmacytoma) or as multiple lesions (multiple myeloma). Solitary plasmacytoma is a rare plasma cell neoplasm. There are 2 separate entities, dependent on the location of the lesion originating in either bone or extramedullary soft tissue. It is defined as a proliferation of monoclonal plasma cells without evidence of significant bone-marrow plasma-cell infiltration. We present a 71-year-old woman who was diagnosed with a solitary plasmacytoma of the bone located in the right third rib after surgical resection. A chest roentgenogram showed a solitary expanding lesion in the right third rib. Chest computed tomography (CT) revealed an osteolytic chest wall tumor. Fluorodeoxyglucose positron emission tomography and CT (PET-CT) showed no abnormal uptake in the whole body, except for the third rib lesion. The patient underwent complete en-bloc resection of the chest wall including ribs, muscle, and parietal pleura. The patient is asymptomatic without any recurrence after one and a half years of follow up.

Driver behavior in car-to-pedestrian incidents: An application of the Driving Reliability and Error Analysis Method (DREAM).

To develop relevant road safety countermeasures, it is necessary to first obtain an in-depth understanding of how and why safety-critical situations such as incidents, near-crashes, and crashes occur. Video-recordings from naturalistic driving studies provide detailed information on events and circumstances prior to such situations that is difficult to obtain from traditional crash investigations, at least when it comes to the observable driver behavior. This study analyzed causation in 90 video-recordings of car-to-pedestrian incidents captured by onboard cameras in a naturalistic driving study in Japan. The Driving Reliability and Error Analysis Method (DREAM) was modified and used to identify contributing factors and causation patterns in these incidents. Two main causation patterns were found. In intersections, drivers failed to recognize the presence of the conflict pedestrian due to visual obstructions and/or because their attention was allocated towards something other than the conflict pedestrian. In incidents away from intersections, this pattern reoccurred along with another pattern showing that pedestrians often behaved in unexpected ways. These patterns indicate that an interactive advanced driver assistance system (ADAS) able to redirect the driver's attention could have averted many of the intersection incidents, while autonomous systems may be needed away from intersections. Cooperative ADAS may be needed to address issues raised by visual obstructions.

Phase II trial of chemotherapy plus bevacizumab as second-line therapy for patients with metastatic colorectal cancer that progressed on bevacizumab with chemotherapy: the Gunma Clinical Oncology Group (GCOG) trial 001 SILK study.

OBJECTIVES: BRiTE and ARIES (observational cohort studies) provided valuable information on continued use of bevacizumab (BV) beyond progression (BBP). This trial evaluates the efficacy and safety of BBP for patients with metastatic colorectal cancer that progressed on first-line chemotherapy. METHODS: A total of 39 patients received FOLFIRI + BV (after FOLFOX + BV) or FOLFOX + BV (after FOLFIRI + BV) as protocol treatment. The primary endpoint was the response rate. Secondary endpoints were overall survival (OS), total survival from initiation of first-line treatment (TS), progression-free survival (PFS), and safety. RESULTS: All 39 treated patients were evaluated for toxic effects. Two patients did not meet all of the eligibility criteria and were excluded from efficacy analyses. The response rate was 16.2%. The disease control rate was 76%. The median PFS was 150 days (range 117-224). The median OS was 417 days (range 233-813). The median TS was 988 days (range 600-1,268). Grade 3/4 adverse events (% of patients) related to treatment were neutropenia (33%), fatigue (23%), and hypertension (18%). CONCLUSIONS: This is the first report to show the effect of BBP in patients who had progressive disease on first-line treatment including BV confirmed by RECIST criteria. This analysis suggests the possibility of prolonged survival with continued use of BV.

The Effects of Percutaneous Endoscopic Gastrostomy on Quality of Life in Patients With Dementia.

BACKGROUND: To examine the effects of percutaneous endoscopic gastrostomy (PEG) on quality of life (QOL) in patients with dementia. METHODS: We retrospectively included 53 Japanese community and tertiary hospitals to investigate the relationship between the newly developed PEG and consecutive dementia patients with swallowing difficulty between Jan 1st 2006 and Dec 31st 2008. We set improvements in 1) the level of independent living, 2) pneumonia, 3) peroral intake as outcome measures of QOL and explored the factors associated with these improvements. RESULTS: Till October 31st 2010, 1,353 patients with Alzheimer's dementia (33.1%), vascular dementia (61.7%), dementia with Lewy body disease (2.0%), Pick disease (0.6%) and others were followed-up for a median of 847 days (mean 805 ± 542 days). A total of 509 deaths were observed (mortality 59%) in full-followed patients. After multivariate adjustments, improvement in the level of independent living was observed in milder dementia, or those who can live independently with someone, compared with advanced dementia, characterized by those who need care by someone: Odds Ratio (OR), 3.90, 95% confidence interval (95%CI), 1.59 - 9.39, P = 0.003. Similarly, improvement of peroral intake was noticed in milder dementia: OR, 2.69, 95%CI, 1.17 - 6.17, P = 0.02. Such significant associations were not observed in improvement of pneumonia. CONCLUSIONS: These results suggest that improvement of QOL after PEG insertion may be expected more in milder dementia than in advanced dementia.

Use of a handheld, semiconductor (cadmium zinc telluride)-based gamma camera in navigation surgery for primary hyperparathyroidism.

The recent development of gamma-ray probes makes it possible to perform radioguided surgery for primary hyperparathyroidism (PHPT). There have only been a few reports, however, regarding the use of a handheld gamma camera to detect parathyroid adenoma intraoperatively. The aim of this preliminary study was to assess the efficiency of a semiconductor gamma camera (eZ-SCOPE AN) in navigation surgery for PHPT. The eZ-SCOPE is designed to be used as a handheld, regional diagnostic imaging device. Eleven consecutive patients with documented primary hyperparathyroidism underwent surgery using this compact camera. Scintigraphy images of the neck by eZ-SCOPE were acquired: 1) before skin incision; 2) after adenoma location; 3) after adenoma excision; and 4) ex vivo imaging of the specimen. In scan-positive cases by preoperative Tc-MIBI, the eZ-SCOPE revealed parathyroid adenoma in all cases (100%), whereas ultrasound and CT showed a single adenoma in 63.6 and 72.7 per cent of cases, respectively. Navigation surgery for PHPT using the eZ-SCOPE permitted intraoperative identification and removal of parathyroid adenoma in all cases. Scintigraphy images of the neck by eZ-SCOPE also revealed a single adenoma even before skin incision. Our results suggest that Tc-MIBI scintigraphy with the eZ-SCOPE is useful for navigation surgery for PHPT. The eZ-SCOPE is useful for skin marking and could be easily applied for minimally invasive radioguided parathyroidectomy in scan-positive cases.

Accuracy of intraoperative macroscopic diagnosis of sentinel node metastases in breast cancer: is accurate prediction possible?

BACKGROUND: Accurate intraoperative diagnosis of sentinel lymph node (SLN) metastases enables the selection of patients who require axillary lymph node dissection, thus avoiding an additional operation. In this study we investigated the accuracy of intraoperative macroscopic diagnosis of SLN metastases in patients with breast cancer. METHODS: SLNs from 276 breast cancer patients with clinically negative nodes were analyzed by macroscopic examination. The results of intraoperative macroscopic diagnosis were compared with those of frozen section analysis. RESULTS: The sensitivity, specificity, overall accuracy, and false negative rate of SLN biopsy in the assessment of node status were 82.1%, 100%, 96.4%, and 17.9%, respectively, for frozen section analysis, and 57.1%, 95.5%, 87.7%, and 42.9%, respectively, for macroscopic evaluation. Even in patients with node metastasis >7 mm, the false negative rate of macroscopic evaluation was 11.1%. CONCLUSIONS: Our results suggest that macroscopic diagnosis is less effective in predicting lymph node status in breast cancer than frozen section analysis. These findings imply that intraoperative macroscopic evaluation of sentinel nodes is never predictive of the final pathology.

Countermeasures to prevent detection failure of a vehicle approaching on collision course.

OBJECTIVE: This study investigated causal factor of perceptual failure and possible countermeasure of crossing path crashes at clear-sighted unsignalised intersections. BACKGROUND: Crossing path crashes involving two vehicles at intersections are a common and serious problem, and perceptual failure has been identified as a predominant causal factor. Previous studies have showed that late detection of a crossing vehicle frequently occurs even when there are no visual obstructions, at such as rural intersections. METHOD: With using a fixed-based driving simulator, three experiments were performed to investigate a driver's ability to detect a periphery presented cross traffic while approaching an intersection. In Experiment 1, drivers' ability to detect crossing vehicles in their peripheral field of view was studied, both in conditions of vehicles following a collision and a non-collision trajectory. In Experiment 2, we examined whether abrupt appearance of a vehicle on collision course would improve detection performance. In Experiment 3, we tested potential of collision warning, if it affects voluntary visual scanning, improving the detection performance regarding hazards cross traffic. RESULTS: The results of Experiment 1 showed that vehicles on collision course vehicles were detected late. This suggested that the late detection could be related to the lack of motion visible in the peripheral view. In Experiment 2, it was found that abrupt appearance effect ("pop-up" from road side occluding furniture) improves detection performance of a crossing vehicle. The results of Experiment 3 demonstrated that cross traffic collision warnings were beneficial for preventing late detection responses by means of encouraging voluntary visual scanning. CONCLUSION: Less attention attractive visual properties of hazardous cross traffic attributed to mutual approaching course can cause recognition failure. Drivers' gaze shift to potential conflicting direction, either reflective or voluntary manner, is crucially important for preventing crossing path crashes at such as rural intersections.

Clinical study of inguinal and femoral incarcerated hernias.

PURPOSE: Inguinal and femoral hernias are common disorders associated with aging. Incarcerated external hernias, however, are often fatal. This study investigated the prognostic factors in patients with incarcerated hernias. METHODS: The study reviewed 38 patients (aged 35-97 years) diagnosed with incarcerated hernias who underwent emergency surgery. The patients were divided into those with or without a small intestinal resection, and they were then analyzed according to time from onset of symptoms to surgery. RESULTS: The time from symptom onset to surgery was significantly longer in the resection group than in the group without resection. The patients were divided into those treated within or after 12 h using a receiver-operating characteristic curve. A sensitivity of 71.4% and a specificity of 83.4% were obtained using the time from symptom onset to operation of 12 h as a cutoff value. More patients who underwent surgery after 12 h from the onset of symptoms required an intestinal resection. Patients who underwent surgery later than 12 h after the onset of symptoms also stayed in the hospital longer than those operated on within 12 h. CONCLUSIONS: The amount of time that elapses from the onset of symptom to surgery is considered to be an important prognostic factor in patients with incarcerated hernias. Early diagnosis and early treatment are therefore necessary in such patients.

Implication of an Intramammary Sentinel Lymph Node in Breast Cancer: Is This a True Sentinel Node? A Case Report.

BACKGROUND: Intramammary lymph nodes (ILN) are often diagnosed by final histological examination. Recently, sentinel lymph node biopsy (SLNB) has been developed as a new standard in the treatment of breast cancer. However, reports describing intramammary sentinel nodes (ISLNs) are relatively rare, and the clinical significance of metastases in ISLNs is still unclear. CASE REPORT: We herein report a patient with breast cancer with an ISLN that was detected prior to surgery. In the current case, the ISLN contained foci of carcinoma, but the axillary SLNs (aSLN) did not contain such foci. Previous reports related to ISLNs and aSLNs, including our case, are reviewed. Interestingly, there was no case with negative ISLNs and positive aSLNs. CONCLUSIONS: The current and previous cases have shown that axillary lymph node dissection (ALDN) might rely on the aSLN status but not on the ISLN status. The effect on the prognosis or clinical significance in cases with positive ISLNs has not been fully elucidated. Cases of ISLNs found by SLN navigation are discussed in relation to their clinical significance.

The sky blue method as a screening test to detect misplacement of percutaneous endoscopic gastrostomy tube at exchange.

BACKGROUND: During tube exchange for percutaneous endoscopic gastrostomy (PEG), a misplaced tube can cause peritonitis and death. Thus, endoscopic or radiologic observation is required at tube exchange to make sure the tube is placed correctly. However, these procedures cost extensive time and money to perform in all patients at the time of tube exchange. Therefore, we developed the "sky blue method" as a screening test to detect misplacement of the PEG tube during tube exchange. METHODS: First, sky blue solution consisting of indigocarmine diluted with saline was injected into the gastric space via the old PEG tube just before the tube exchange. Next, the tube was exchanged using a standard method. Then, we checked whether the sky blue solution could be collected through the new tube or not. Finally, we confirmed correct placement of the tube by endoscopic or radiologic observation for all patients. RESULTS: A total of 961 patients were enrolled. Each tube exchange took 1 to 3 minutes, and there were no adverse effects. Four patients experienced a misplaced tube, all of which were detectable with the sky blue method. Diagnostic parameters of the sky blue method were as follows: sensitivity, 94% (95%CI: 92-95%); specificity, 100% (95%CI: 40-100%); positive predictive value, 100% (95%CI: 100-100%); negative predictive value, 6% (95%CI: 2-16%). CONCLUSION: These results suggest that the number of endoscopic or radiologic observations to confirm correct replacement of the PEG tube may be reduced to one fifteenth using the sky blue method.