Effect of coronavirus disease 2019 pandemic on children’s visits to the emergency department

Purpose@#In the coronavirus disease 2019 pandemic, it is essential to supplement the changes in visiting patterns of individual emergency departments (EDs) to determine how to allocate emergency medicine resources. We compared the clinical features of children visiting the ED before and during the pandemic. @*Methods@#Children younger than 18 years who visited the ED from February 2019 through December 2020, except January 2020, were enrolled, and divided into those who visited before and after January 2020 (the pre-pandemic and pandemic groups, respectively). We compared the 2 groups in terms of the baseline characteristics (age, sex, mode and route of arrival, cause of visit, and time of visit), chief complaint, ED diagnosis, initial acuity and its accuracy, and ED outcomes (length of stay and disposition). @*Results@#The 31,036 children were categorized into the pre-pandemic (21,027 [67.8%]) and pandemic (10,009 [32.2%]) groups with a 52.4% decrease in the number of visits to the ED in the latter group. This decrease was more prominent in age 2-5 years (from 37.3% to 33.2%; P < 0.001), fever as a chief complaint (from 27.8% to 16.5%), diagnoses related to infection or the respiratory system (from 36.8% to 14.3%) or transfer to the ED (from 8.1% to 6.4%; P < 0.001). In contrast, increases were noted in age 12-17 years (from 14.9% to 17.4%; P < 0.001), injury (from 36.5% to 52.5%; P < 0.001), visits in the evening (from 54.9% to 57.4%; P < 0.001), length of stay longer than 6 hours (from 3.5% to 6.3%; P = 0.033), and low acuity (from 97.8% to 98.2%; P = 0.031). @*Conclusion@#The pandemic has brought about changes in visiting patterns of the ED. This study may help prepare strategies for the appropriate allocation and deployment of emergency medicine resources in the pandemic era.

Application of convolutional neural networks for distal radio-ulnar fracture detection on plain radiographs in the emergency room

Objective@#Recent studies have suggested that deep-learning models can satisfactorily assist in fracture diagnosis. We aimed to evaluate the performance of two of such models in wrist fracture detection. @*Methods@#We collected image data of patients who visited with wrist trauma at the emergency department. A dataset extracted from January 2018 to May 2020 was split into training (90%) and test (10%) datasets, and two types of convolutional neural networks (i.e., DenseNet-161 and ResNet-152) were trained to detect wrist fractures. Gradient-weighted class activation mapping was used to highlight the regions of radiograph scans that contributed to the decision of the model. Performance of the convolutional neural network models was evaluated using the area under the receiver operating characteristic curve. @*Results@#For model training, we used 4,551 radiographs from 798 patients and 4,443 radiographs from 1,481 patients with and without fractures, respectively. The remaining 10% (300 radiographs from 100 patients with fractures and 690 radiographs from 230 patients without fractures) was used as a test dataset. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of DenseNet-161 and ResNet-152 in the test dataset were 90.3%, 90.3%, 80.3%, 95.6%, and 90.3% and 88.6%, 88.4%, 76.9%, 94.7%, and 88.5%, respectively. The area under the receiver operating characteristic curves of DenseNet-161 and ResNet-152 for wrist fracture detection were 0.962 and 0.947, respectively. @*Conclusion@#We demonstrated that DenseNet-161 and ResNet-152 models could help detect wrist fractures in the emergency room with satisfactory performance.

Application of convolutional neural networks for distal radio-ulnar fracture detection on plain radiographs in the emergency room

Objective@#Recent studies have suggested that deep-learning models can satisfactorily assist in fracture diagnosis. We aimed to evaluate the performance of two of such models in wrist fracture detection. @*Methods@#We collected image data of patients who visited with wrist trauma at the emergency department. A dataset extracted from January 2018 to May 2020 was split into training (90%) and test (10%) datasets, and two types of convolutional neural networks (i.e., DenseNet-161 and ResNet-152) were trained to detect wrist fractures. Gradient-weighted class activation mapping was used to highlight the regions of radiograph scans that contributed to the decision of the model. Performance of the convolutional neural network models was evaluated using the area under the receiver operating characteristic curve. @*Results@#For model training, we used 4,551 radiographs from 798 patients and 4,443 radiographs from 1,481 patients with and without fractures, respectively. The remaining 10% (300 radiographs from 100 patients with fractures and 690 radiographs from 230 patients without fractures) was used as a test dataset. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of DenseNet-161 and ResNet-152 in the test dataset were 90.3%, 90.3%, 80.3%, 95.6%, and 90.3% and 88.6%, 88.4%, 76.9%, 94.7%, and 88.5%, respectively. The area under the receiver operating characteristic curves of DenseNet-161 and ResNet-152 for wrist fracture detection were 0.962 and 0.947, respectively. @*Conclusion@#We demonstrated that DenseNet-161 and ResNet-152 models could help detect wrist fractures in the emergency room with satisfactory performance.

Validation and modification of HEART score components for patients with chest pain in the emergency department

Objective@#This study aimed to clarify the relative prognostic value of each History, Electrocardiography, Age, Risk Factors, and Troponin (HEART) score component for major adverse cardiac events (MACE) within 3 months and validate the modified HEART (mHEART) score. @*Methods@#This study evaluated the HEART score components for patients with chest symptoms visiting the emergency department from November 19, 2018 to November 19, 2019. All components were evaluated using logistic regression analysis and the scores for HEART, mHEART, and Thrombolysis in Myocardial Infarction (TIMI) were determined using the receiver operating characteristics curve. @*Results@#The patients were divided into a derivation (809 patients) and a validation group (298 patients). In multivariate analysis, age did not show statistical significance in the detection of MACE within 3 months and the mHEART score was calculated after omitting the age component. The areas under the receiver operating characteristics curves for HEART, mHEART and TIMI scores in the prediction of MACE within 3 months were 0.88, 0.91, and 0.83, respectively, in the derivation group; and 0.88, 0.91, and 0.81, respectively, in the validation group. When the cutoff value for each scoring system was determined for the maintenance of a negative predictive value for a MACE rate >99%, the mHEART score showed the highest sensitivity, specificity, positive predictive value, and negative predictive value (97.4%, 54.2%, 23.7%, and 99.3%, respectively). @*Conclusion@#Our study showed that the mHEART score better detects short-term MACE in high-risk patients and ensures the safe disposition of low-risk patients than the HEART and TIMI scores.

Outcomes of living donor kidney transplantation in diabetic patients: age and sex matched comparison with non-diabetic patients

BACKGROUND/AIMS: Kidney transplantation (KT) reportedly provides a significant survival advantage over dialysis in diabetic patients. However, KT outcome in diabetic patients compared with that in non-diabetic patients remains controversial. In addition, owing to recent improvements in the outcomes of KT and management of cardiovascular diseases, it is necessary to analyze outcomes of recently performed KT in diabetic patients. METHODS: We reviewed all diabetic patients who received living donor KT between January 2008 and December 2011. Each patient was age- and sex-matched with two non-diabetic patients who received living donor KT during the same period. The outcomes of living donor KT were compared between diabetic and non-diabetic patients. RESULTS: Among 887 patients, 89 diabetic patients were compared with 178 non-diabetic patients. The incidence of acute rejection was not different between the diabetic and non-diabetic patients. Urinary tract infection and other infections as well as cardiovascular events occurred more frequently in diabetic patients. However, diabetes, cardiovascular disease, and infection were not significant risk factors of graft failure. Late rejection (acute rejection after 1 year of transplantation) was the most important risk factor for graft failure after adjusting for diabetes mellitus (DM), human leukocyte antigen mismatch, rejection and infection (hazard ratio, 56.082; 95% confidence interval, 7.169 to 438.702; p < 0.001). Mortality was not significantly different between diabetic and non-diabetic patients (0 vs. 2, p = 0.344 by log-rank test). CONCLUSIONS: End-stage renal disease patients with DM had favorable outcomes with living donor kidney transplantation.

Use of fludrocortisone for intradialytic hypotension

Intradialytic hypotension during dialysis adversely affects a patient's prognosis and increases mortality. We report a case in which intradialytic hypotension that persisted after the administration of midodrine was relieved after the use of fludrocortisone. Administration of 0.2 mg of fludrocortisone occurred 30 minutes before dialysis. We compared 45 sessions of dialysis without fludrocortisone administration and 45 sessions of dialysis with fludrocortisone administration in one patient. The number of times in which systolic blood pressure became lower than 80 mmHg and the number of early terminations of dialysis due to a decrease in systolic blood pressure were higher in the sessions without fludrocortisone administration than in the sessions with fludrocortisone administration (P < 0.05). Fludrocortisone may be helpful for the treatment of intradialytic hypotension that does not respond to midodrine administration.

Calculated Brain CT Angiography Volumes of Lacrimal Glands in Normal Korean Orbits

PURPOSE: To determine the size range of lacrimal glands calculated from Brain CT angiography. METHODS: A retrospective review of 107 CT scans of 214 orbits was performed. Aquaris Intuition Viewer software was used to calculate the volumes. RESULTS: The mean volume of the lacrimal gland was 0.655 cm3 in right orbits and 0.595 cm3 in left orbits, 0.616 cm3 in men and 0.625 cm3 in women. There was a significant difference between right and left (p = 0.012) but no difference between men and women (p = 0.725). Linear regression analyses revealed that there was an inverse relationship between gland volume and age (Pearson r = -0.433, p < 0.001). CONCLUSIONS: This is the first study to report the normal volume range of Korean lacrimal glands as measured by CT scans. A difference was detected in the volume between right and left lacrimal glands. The volume of the lacrimal gland decreased with age, and there were no gender differences.

Fetal and Maternal Outcomes of Pregnancy in Women with IgA Nephropathy / 대한신장학회지

PURPOSE: To determine the effects of: 1) IgA nephropathy (IgAN) on fetal outcome; 2) gestation on maternal outcome; and 3) pregnancy on the long-term prognosis of IgAN. METHODS: Ninety pregnancies in 75 women with biopsy-proven IgAN between 1989 and 2004 were evaluated retrospectively. The long-term prognosis of IgAN was determined by estimating glomerular filtration rate (GFR) 5 years after delivery and comparing the results from 75 matched non-pregnant patients with IgAN. RESULTS: Multivariate analysis showed that baseline renal function was the only predictor of fetal outcome. Hypertension and impaired renal function before pregnancy were associated with poor maternal outcome during pregnancy, whereas histologic grade was related to the long-term prognosis of IgAN. Five years after delivery, GFR did not differ between pregnant (63.6+/-33.4 mL/min) and non-pregnant (63.2+/-32.5 mL/min) women with IgAN. CONCLUSION: Impaired renal function appears an important prognostic factor for fetal outcome. Short- term maternal prognosis was dependent on pre-pregnancy clinical parameters associated with IgAN, whereas long-term prognosis was dependent on histopathologic parameters of IgAN itself. Pregnancy per se had no adverse effects on the natural history of IgAN.

Comparison of Drug-Eluting Stent and Bare Metal Stent in Reducing Adverse Cardiac Event after Coronary Stenting in Hemodialysis Patients / 대한신장학회지

PURPOSE: The patients treated with hemodialysis have been known to have a high 1-year mortality rate after percutaneous coronary intervention (PCI). We evaluated the clinical benefits of drug-eluting stent (DES), compared to bare-metal stent (BMS) in Korean hemodialysis patients. METHODS: We studied 72 hemodialysis patients (M:F=49:23, age 60+/-11 years) treated with percutaneous coronary intervention (PCI) from January, 1999 to February, 2006. Forty four patients (M:F=28: 16, age 60+/-11 years) treated with DES and 28 patients (M:F=21:7, age 60+/-12 years) with BMS were enrolled. A composite of major adverse cardiac and cerebral endpoints (MACCE) was defined as all-cause death, myocardial infarction, stroke, and target-vessel revascularization (TVR). We compared the incidence of MACCE between DES and BMS group. RESULTS: A composite of MACCE occurred in none in DES group (n=44) and 4 in BMS group (n=28) within 3 months after coronary stenting (Kaplan-Meier survival analysis: 0% vs 14%, respectively, p= 0.02). After 3 months, there was no difference in the incidence of primary end points between two groups. Multi-vessel disease (OR 2.47, 95% CI 1.02-6.11, p<0.05) was associated with a significant increase in the incidence of MACCE within 18 months after coronary artery stenting CONCLUSION: DES may be superior to BMS in reducing adverse cardiac outcome at early period after coronary stenting in HD patients. However, this study showed no significant difference with the lapse of time.

Comparison of Erythropoietic Effect between Epoetin-alpha and Darbepoetin-alpha in Hemodialysis Patients: A Randomized Crossover Study / 대한신장학회지

PURPOSE: We aim to compare the erythropoietic effects of epoetin-alpha (EA, 4000 IU SC thrice a week) with those of darbepoetin-alpha (DA, 60ug IV weekly, conversion rate to EA=200:1). METHODS: Forty one stable hemodialysis patients were enrolled in this randomized crossover study. After a washout period of erythropoietin stimulating agents (ESA), the patients with hemoglobin (Hb) level of 11.0 g/dL, we stopped ESA. When Hb level decreased to 30% change in EA efficiency relative to DA efficiency. CONCLUSION: There was no significant difference in erythropoietic parameters for both EA and DA.

A Case of Familial Atypical Hemolytic Uremic Syndrome Associated with Complement Factor H Mutation in Adults / 대한신장학회지

The hemolytic uremic syndrome is a clinical syndrome defined by the presence of thrombocytopenia, microangiopathic hemolytic anemia and acute renal failure. Atypical hemolytic uremic syndrome (aHUS) which is not usually associated with prodromal symptoms, especially diarrhea, has a higher mortality rate and a stronger tendency to progress to chronic renal failure. In approximately 30-50% of patients with aHUS, mutations have been detected in complement factor H, membrane cofactor protein or factor I. Mutations in the complement regulator factor H are the most frequent and have a very poor prognosis, with most patients developing ESRD. We have experienced a 33-year-old man with a family history of renal failure diagnosed as aHUS resulted from factor H mutation, for whom we carried out hemodialysis, plasmapheresis and other conservative management.

SIADH and Guillain-Barre Syndrome Associated with Pulmonary Tuberculosis / 대한신장학회지

Hyponatremia is one of the most common electrolyte disturbances in nephrologic clinical setting. SIADH is one of the causes of hyponatremia and can be accompanied with various conditions such as malignancies, infections and nervous system diseases. Guillain-Barre syndrome is an acute inflammatory polyneuropathy. It is reported that SIADH can be accompanied with Guillain-Barre syndrome although the mechanism is unclear. Symptoms of Guillain- Barre syndrome such as general weakness, decreased consciousness, and seizure are similar to those of hyponatremia. Thus the diagnosis of Guillain-Barre syndrome can be delayed if they coexist. Because Guillain-Barre syndrome leads to severe respiratory failure in its disease course and mechanical ventilatory assistance is mandatory for such cases, early diagnosis and treatment is critical. Korea is still endemic area for tuberculosis and clinicians often experience pulmonary tuberculosis in practice. But pulmonary tuberculosis-associated SIADH and Guillain-Barre syndrome were not reported in Korea. So far, 2 cases of gastrointestinal infection-associated SIADH and Guillain-Barre syndrome were reported. Hence, authors report here the case of SIADH associated Guillain-Barre syndrome associated with pulmonary tuberculosis.

A Case of Interstitial Pneumonitis Associated with Sirolimus Treatment in Renal Transplantation Recipient / 대한신장학회지

Sirolimus is a promising immunosuppressive drug for renal transplantation to avoid nephrotoxicity of calcineurin inhibitor. However, it has been associated with uncommon but, important pulmonary toxicity. We present a case of sirolimus related dyspnea with abnormal chest radiographic finding in a 63 year old male renal transplantation recipient. There was no evidence of bacterial, fungal, or viral infection. Dose reduction of sirolimus resulted in a significant improvement of the symptoms and chest radiographic finding.

Calcium-Sensing Receptor Gene Polymorphism is Associated with the Parathyroid Response to Low Calcium Dialysate in Hemodialysis Patients with Low Parathyroid Hormone Secretion / 대한신장학회지

PURPOSE: Low level of parathyroid hormone (PTH) is a risk factor that might cause hip fracture in dialysis patients. Low calcium dialysate (LCD) has been suggested as an approach to increase PTH level. The calcium-sensing receptor (CaSR) polymorphism is known to be associated with the sensitivity to extracellular calcium. METHODS: We prospectively investigated the role of genetic polymorphism of CaSR codon 990 as one cause of the different parathyroid responses to LCD in maintenance hemodialysis (HD) patients. 48 patients, using 3.5 mEq/L calcium dialysate, with intact PTH below 100 pg/ml for the last one year underwent HD sessions on 2.5 mEq/L calcium dialysate for 12 weeks. Serum intact PTH, total calcium, phosphorus, alkaline phosphatase (ALP) and bone-specific ALP (BAP) were measured monthly. The CaSR gene from peripheral lymphocytes was amplified to confirm the genotype by polymerase chain reaction. RESULTS: According to the CaSR genetic polymorphism, subjects were divided into 3 groups, A/A (14.6 %), A/G (45.8%) and G/G (39.6%). Twelve weeks later, intact PTH (48.5+/-25.4 to 89.0+/-49.4 pg/mL, p<0.01), and ALP (78.7+/-25.7 to 87.4+/-27.2 IU/L, p<0.01) increased significantly in G/G group, but not in non-G/G groups. However, BAP significantly increased in both G/G group (24.3+/-11.9 to 29.5+/-10.6 U/L, p<0.01) and in non-G/G groups (21.4+/-4.5 to 26.1+/-9.1 U/L, p<0.01). During the study period, levels of corrected total calcium and phosphorus were not significantly changed. CONCLUSION: The CaSR polymorphism, G/G genotype, strongly influenced the responsiveness of parathyroid gland to LCD, compared with non-G/G genotypes. However, bone formation may occur actively on LCD, irrespective of CaSR genetic polymorphism.

A case of lactic acidosis caused by thiamine deficiency / 대한내과학회지

Lactic acidosis commonly occurs in association with shock. We encountered lactic acidosis in a patient with normal blood pressure. The patient was a 17 year-old man with acute lymphocytic leukemia. He was admitted for bone marrow transplantation. During hospitalization, he relied on total parenteral nutrition due to his poor oral intake. On the 37th day after admission, he developed lactic acidosis without an episode of hypotension or any causative medication. Because vitamins were not included in the parenteral nutrition, we prescribed thiamine replacement, and this corrected the acidosis within a few hours. Thiamine (in its active derivative) is a coenzyme for pyruvate dehydrogenase; thus, its deficiency causes accumulation of pyruvate and lactate. This case suggests that thiamine deficiency should be included in a differential diagnosis of lactic acidosis in patients who are on total parenteral nutrition without vitamin supplementation.

Clinical Significance of Continuous Veno-Venous Hemodiafiltration as an Initial Renal Replacement Therapy for Acute Renal Failure after Cardiovascular Surgery / 대한신장학회잡지

BACKGOUND: Although continuous venovenous hemodiafiltration (CVVHDF) has many therapeutic advantages, previous studies did not report the improvement of survival rate by CVVHDF compared to that by hemodialysis (HD). It could be attributed to that they did not analyze the results under the appropriate stratification of severity and to multiorgan failure. METHODS: We performed retrospective study to compare the outcomes of 88 patients with acute renal failure after major cardiovascular surgery(s). Among them, 48 patients (M:F=32:16, Age 58+/-11 years) were treated by CVVHDF and 40 patients (M:F=27:13, Age 59+/-10 years) were treated by HD. The severity of illness was estimated by APACHE III score system at the initiation of renal replacement therapy (RRT) and we also evaluated renal outcome and survival. RESULTS: There was no significant difference between two groups in baseline characteristics, cause of surgery, survival rate and renal outcome. However, compared with those of HD group, CVVHDF group showed longer period of application with mechanical ventilator (p=0.001), longer period of vasopressor use (p<0.001), longer stay in intensive care unit (p=0.004) and higher APACHE III score at the initiation of renal replacement therapy (p=0.009). Among those with APACHE III scores over 90, survivors existed in CVVHDF group with the survival rate of 50%. In contrast, there was no one who survived in HD group (p=NS). CONCLUSION: Although this study revealed that CVVHDF could be more useful than HD as an initial RRT for the patients with renal failure after major cardiovascular surgery, the randomized prospective study will be required to accept clinical usefulness of CVVHDF.

Low Dose Intravenous Iron Sucrose Maintenance Therapy in Hemodialysis Patients with Adequate Iron Storage / 대한신장학회잡지

BACKGOUND: In addition to recombinant human erythropoietin (rHuEPO) adequate iron replacement is essential to treatment of anemia in hemodialysis (HD) patients, and intravenous iron therapy has been recommended recently. But, low dose (100-200 mg/ month) intravenous iron sucrose regimen as a "maintenance therapy" in HD patients with adequate iron storage has not been established well. METHODS: We included the 40 of HD patients with serum ferritin of 200-500 ng/mL receiving rHuEPO therapy. During 4 months of study period, 100-200 mg/month of iron sucrose was administrated. rHuEPO doses were titrated to maintain target hematocrit (Hct) of 30%. To evaluate efficacy of iron sucrose, we compared serum ferritin, TSAT and rHuEPO requirements before and after iron sucrose therapy. RESULTS: Thirty-nine patients [mean age 61+/-13 yrs, M:F=20:19] completed this study. After low dose intravenous iron sucrose maintenance therapy, serum ferritin and TSAT significantly increased (370+/-84 vs. 518+/-155 ng/mL, p800 ng/mL was observed during the study. CONCLUSION: Low dose intravenous iron sucrose maintenance therapy is effective and safe in the HD patient receiving rHuEPO therapy with adequate iron storage.

Distribution of Cardiac Troponin T in Continuous Hemodialysis Patients and Clinical Characteristics of Patients with Elevated Cardiac Troponin T / 대한신장학회잡지

PURPOSE: The leading cause of death of end-stage renal failure is cardiovascular disease. Elevated cardiac troponin T (cTnT) is associated with the high incidence and prevalence of cardiovascular disease and increased mortality and morbidity. Therefore the aim of this study was to examine the distribution of cTnT in continuous hemodialysis patients and clinical significance of elevated cTnT. METHODS: We studied 183 asymptomatic patients who were undergoing chronic continuous hemodialysis treatment. Predialysis blood samples also used to measure hematocrit, albumin, total cholesterol. We evaluated the history of coronary artery disease and the etiologies of renal disease using chart reviews and patients interviews and cardiac status were determined by electrocardiography, two-dimensional echocardiography and coronary angiography. Predialysis cTnT was measured by a second-generation assay, Elecsys 1010 and we considered patients with serum cTnT>0.1 ng/mL as positive. RESULTS: Forty two patients (23%) had cTnT greater than 0.1 ng/mL. Ischemic heart disease was observed in 18.6% (34/183), diabetes mellitus (DM) in 53.6% (98/183), hypertension in 92.3% (169/183) and left ventricular hypertrophy in 67.2% (123/183). cTnT revealed significantly higher level in the patients with age over 60, male, DM, pulse rate over 60 mmHg, ischemic heart disease (IHD), hematocrit under 36% and albumin under 3.7 g/dL. cTnT levels significantly correlated to ischemic heart disease, DM and male. CONCLUSION: In hemodialysis patients, cTnT level is related to age, sex, DM, pulse rate, IHD, hematocrit and albumin. A prospective study is necessary to provide information on the effect of correcting the controllable factors on cTnT level and cardiovascular mortality in maintenance hemodialysis patients.

Comparison of Serum Beta 2-Microglobulin and 24 hour Urinary Creatinine Clearance as a Prognostic Factor in Multiple Myeloma

A new staging system for multiple myeloma (MM) has utilized serum concentrations of beta 2-microglobulin (S beta2 M) and albumin as important prognostic factors for survival. Since S beta2 M is an indicator of glomerular filtration rate, we compared the prognostic values of S beta2 M and 24-hr urinary creatinine clearance (Ccr) in patients with MM. We retrospectively reviewed the records of 170 MM patients from January 1996 to November 2003 whose 24-hr urinary Ccr was available at the time of diagnosis. We found that pretreatment S beta2 M was inversely related to Ccr (Spearman's correlation coefficient=-0.787). In univariate analysis, the hazard ratio (HR) of death was 1.043 (p<0.001) for S beta2 M and 0.985 (p<0.001) for Ccr. Multivariate analysis showed that S beta2 M (HR 1.030, p=0.010) and Ccr (HR 0.993, p=0.059) were significant prognostic factors in patients' survival. In conclusion, 24-hr urinary Ccr may be utilized for staging of patients with MM.

The Attack of Ventricular Arrhythmia Caused by Low Potassium Level in Hemodialysis Patients / 대한신장학회잡지

ESRD patients have higher cardiovascular mortality risk than the general population. Increased QT dispersion has been shown to be a risk factor for cardiac arrhythmia in chronic hemodialysis patients with diabetes or arterial disease. It is known that QT dispersion is significantly prolonged in postdialysis than in predialysis. It is associated with a decrease in serum potassium. During hemodialysis, serum potassium is decreased and QT dispersion increases. Therefore ventricular arrhythmia frequently occurs in the latter half of dialysis. We report 2 cases of ventricular arrhythmia caused by potassium removal during dialysis in chronic hemodialysis patients.