Analysis of HCV RNA Genotypes and Quantitative Values of Korean HCV NAT Reactive Blood Donors / 대한수혈학회지

BACKGROUND@#Ever since the Korean Red Cross adopted HCV NAT for blood donor screening in 2005, HCV NAT reactive donors have been identified every year. The identification of the clinical features for these HCV NAT reactive donors may be helpful for the treatment and prevention of HCV infection.@*METHODS@#We analyzed HCV NAT reactive samples to examine the distribution of HCV RNA genotypes and the quantitative values of 128 and 47 HCV NAT reactive samples in 2007 and 2017, respectively.@*RESULTS@#The dominant genotype of the HCV NAT reactive donors was 1b showing 50.0% (64/128) in 2007 and 44.7% (21/47) in 2017. The genotype 2a was the second most dominant at 40.6% (52/128) in 2007 and 40.4% (19/47) in 2017. The mean titers of HCV RNA were 3.17×106 IU/mL in 2007 and 2.61×106 IU/mL in 2017. More than 90% of the donors showed a range of more than 1,000 IU/mL for the HCV RNA titer. There was no difference of quantitative values in the different genotypes.@*CONCLUSION@#In this study, the distribution of HCV RNA genotypes in Korean blood donors showed a similar pattern compared to that of the general population. There was no correlation between the quantitative values and genotypes in the HCV NAT reactive blood donors, and there was no significant variation in the distribution of HCV RNA genotypes of the HCV NAT reactive donors between 2007 and 2017. Yet it is thought that the characteristics of HCV NAT reactive samples in other years have to be analyzed to achieve more significant results.

Investigation of the Association of HCV or HIV Markers in Non-Discriminated Blood Donations / 대한수혈학회지

HBV core antibody and surface antibody test are currently conducted for those donors showing non-discriminated reactive (NDR) results on a nucleic acid amplification test (NAT) as a blood donor screening assay. It is necessary to investigate the relationship with HCV or HIV in the donors showing NDR results. From June 12th, 2012 to December 31st, 2018, 0.05% (9,020/17,798,461) donors showed NDR results on a NAT. Among the donors showing NDR results, 17 and 18 donors showed positive results on serological assay of HCV and HIV, respectively. 23 donors with NDR results showed positive results on the serological assay or NAT for HCV or HIV on the following donation. Further study and more accumulated data are required because it may be difficult to find the cause of NDR results by the current serological assay that is used for screening blood donors.

Erratum: Author's order correction Comparison of the Effectiveness in the Application of Competitive and Noncompetitive Internal Control for the Laboratory Developed Polymerase Chain Reaction / 대한수혈학회지

Corrections of author names are needed.

Results of Reentry Test for the Deferred Donors after Non-Discriminated Reactive in Nucleic Acid Amplification Test / 대한수혈학회지

BACKGROUND: Since December 15 2017, donors showing a non-discriminated reactive (NDR) result in the nucleic acid amplification test (NAT) have been temporarily deferred and anti-HBc and anti-HBs assays as additional tests were performed. Donors with an anti-HBc reactive result and less than 100 IU/L of anti-HBs could not be released and can request a reentry test after more than six months. This study considered the effects of additional tests for NDR donors by analyzing the reentry test results in donors not released in the additional test. METHODS: This study examined the results of the additional test for NDR donors from January 2017 to September 2018 and the reentry test of the donors not released in the additional test. RESULTS: NAT was conducted on 4,706,051 blood donors over the period and 2,545 (0.05%) of them showed NDR. A total of 656 (25.8%) of the NDR donors were not released in the additional test. Among them, 246 donors requested a reentry test; 222 (90.2%) donors were not reentered, and 23 (10.4%) showed HBV NAT reactive results in the reentry test. Among the remaining 24 reentered donors, 2 donors (8.3%) showed anti-HBc nonreactive results in the reentry test and 22 donors (91.7%) showed higher than 100 IU/L of anti-HBs. CONCLUSION: The follow-up of NDR donors may be significant because some donors showed different results between screening test and reentry test. In addition the effectiveness of the introduction of additional tests for the NDR donors has been proved to be effective.

Comparison of the Effectiveness in the Application of Competitive and Noncompetitive Internal Control for the Laboratory Developed Polymerase Chain Reaction / 대한수혈학회지

BACKGROUND: A nucleic acid amplification test was adopted to detect transfusion-transmitted infectious agents. In the case of HTLV, however, there was no internal control (IC) because the laboratory developed polymerase chain reaction (laboratory-developed PCR) was used. In this study, noncompetitive IC was constructed for the laboratory-developed PCR of HTLV and the effectiveness was compared with the competitive test that was constructed in a previous study. METHODS: As a competitive IC, plasmid DNA, including the primer recognition sequence for the amplification of the HTLV pX region, was constructed. As a noncompetitive IC, an additional primer was constructed for the amplification of the housekeeping gene, the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene. The performance of the competitive and noncompetitive IC was verified and compared using 10 HTLV positive samples and 10 negative samples. In addition, the detection limits in the assay adopting competitive IC and noncompetitive IC were compared. RESULTS: In the case of competitive IC applications, all 10 positive samples were positive and all 10 negative samples were negative. In the case of noncompetitive IC applications, however, one positive sample was not detected. The detection limit of the assay using competitive IC was 100 pg and that of the assay using noncompetitive IC was 1 ng. CONCLUSION: Although the manufacturing processes is not required using noncompetitive IC, the adoption of competitive IC is more effective to ensure the assay results because the ability of detection of the assay adopting competitive IC was better than that using noncompetitive IC.

Analysis of Reentry Test for the Donors Showing Reactivity or Grey Zone in a HBV Surface Antigen Assay by a Chemiluminescent Immunoassay / 대한수혈학회지

BACKGROUND: If donors who were deferred due to the reactivity or grey zone in HBV surface antigen (HBsAg) assay want to donate blood again, they need to pass reentry tests. On the other hand, approximately half of the donors who are subject to the reentry tests cannot be reentered. This study examined the association between the sample to cutoff (S/Co) value of the HBsAg assay and the final results of the reentry test. METHODS: This study analyzed the S/Co values of the HBsAg assay and the final results of the reentry tests for the 3,947 donors from January 2008 to December 2017 using the database of Blood Information Management System of the Korean Red Cross. RESULTS: 1,767 donors (44.8%) were not reentered among 3,947 deferred donors. Among 1,585 donors showing ≥10 of the S/Co value in the HBsAg screening test, 1,542 donors (97.3%) were not reentered. The additional reentry tests were performed on 120 donors who were not reentered in the first reentry test; 98 donors (81.7%) were still not reentered. Overall, 4.6% of the donors showing a grey zone in the HBsAg assay were not reentered. CONCLUSION: The reentry test needs to be restricted for the deferred donors showing a more than 10 S/Co value. The application of the grey zone of current HBsAg assay will need to be continued to enhance the HBV-related blood safety.

Construction and Application of Internal Control for Laboratory-Developed HTLV PCR / 대한수혈학회지

BACKGROUND: For donor samples showing reactive results in a human T-cell lymphotropic virus (HTLV) antibody test along with indeterminate results in Western blot assay, HTLV nucleic acid amplification test using laboratory-developed polymerase chain reaction (PCR) was performed. It is necessary to construct an adequate internal control (IC) to evaluate the accuracy of the results since we did not use an IC in the laboratory-developed PCR. METHODS: As a competitive IC, plasmid DNA containing the primer recognition sequence for amplification of the HTLV pX region was constructed. We determined the adequate concentration of the IC, which was added to the samples to evaluate the accuracy of the test results. RESULTS: When the plasmid DNA was added to the HTLV-positive samples, the amplified product of IC (400 bp) was detected with the HTLV gene (230 bp). The adequate concentration of plasmid DNA added as an IC was 1 pg. CONCLUSION: The construction of plasmid DNA as a competitive IC is an efficient method to evaluate accuracy of the test results. However, the production process for the competitive IC must be further developed. Therefore, it is necessary to compare with the performance of a non-competitive IC.

Estimation of the Outbreaks of Transfusion-Transmissible Emerging Infectious Diseases in Korean Blood Donors by Public Data / 대한수혈학회지

BACKGROUND: Transfusion transmissible emerging infectious diseases (EIDs) is a potential risk to the safety of blood transfusions due to the lack of donor screening assays. To prevent the spread of EIDs through blood transfusions, we attempted to predict the possibility of blood donations from people with EIDs using a public database. METHODS: We used the Disease Web Statistics System of the Korean Centers for Disease Control and Prevention and Korean Statistical Information Service. We estimated the possibility of blood donations from people with EIDs using the public database combined with the database made available by the Blood Information Management System of the Korean Red Cross. RESULTS: Among the transfusion transmissible EIDs, Babesiosis, Leishmaniasis, West Nile fever, Chikungunya, and Dengue fever were reported in Korea. All of them were cases imported from abroad. Although the number of reported cases of Babesiosis, Leishmaniasis, West Nile fever, and Chikungunya were less than 10 per year until 2016, the reported cases of Dengue fever gradually increased from 2001, and there were 318 cases of Dengue fever in 2016. CONCLUSION: The possibility of blood donation from people with transfusion-transmissible EIDs was low because all reported transfusion-transmissible EIDs in Korea were from foreigners and blood donation from Koreans who returned from abroad was restricted for a period of a month. Nonetheless, preventive strategy for donation from people is necessary given the recent increase in Dengue fever.

Consideration of Appropriateness of Application of Immunoblot Assay as a Reentry Test for HCV or HIV Screening Reactive Donors / 대한수혈학회지

BACKGROUND: Currently, serological assay, immunoblotting, and nucleic acid amplification test (NAT) are required as reentry tests for deferred donors with hepatitis C virus (HCV) or human immunodeficiency virus (HIV) screening reactive result. However, immunoblotting must be performed even for serological nonreactive donors. In this study, the efficacy of immunoblot applications for serological nonreactive donors in donor reentry procedures was examined. METHODS: We analyzed non-qualified donors with immunoblot results from 2011 to 2015 in Korea and investigated reentry procedures related with HCV or HIV in other countries. RESULTS: Percentages of donors who could not be released due to immunoblot results even with serological nonreactive results were 54.2% (1,824/3,367) for HCV and 35.9% (4,300/11,964). In the case of 662 donors, their results were considered to be different using other assay kits or based on other criteria. In other countries, immunoblotting is not required as a donor reentry test. CONCLUSION: Indeterminate or reactive immunoblotting results in serological nonreactive donors were due to nonspecific reactions. It is not reasonable to apply immunoblotting to serological nonreactive donors. Therefore, we suggest that immunoblot assays be excluded from the reentry test.

Comparison of the Results among Automated Treponema pallidum Latex Agglutination, Rapid Plasma Regain and Treponema pallidum Particle Agglutination, Rapid Plasma Regain Card Test in Blood Donors / 대한수혈학회지

BACKGROUND: The Korean Red Cross blood laboratory centers use Treponema pallidum particle agglutination assay on the PK7300 instrument as a primary donor screening test for syphilis, and semi-quantitative TPPA and RPR card as supplementary tests. We compared the results of Treponema pallidum latex agglutination and RPR tests on the automated analyzer with those of TPPA and RPR card tests. METHODS: A total of 1,000 samples with negative TPPA results and 103 samples with positive TPPA results (> or =1:80 titers) were evaluated in this study. HiSens Auto TP, RPR (HBI, Anyang, Korea) and Mediace TPLA, RPR (Sekisui, Tokyo, Japan) reagents were used on the automated analyzer. FTA-ABS test was performed as a confirmatory test to evaluate the sensitivity and specificity of HiSens Auto TPLA, RPR and Mediace TPLA, RPR reagents. RESULTS: The concordance rate between HiSens Auto TP, Mediace TPLA and TPPA was 95.5% and 95.4%, respectively. The concordance rate between HiSens Auto RPR, Mediace RPR and RPR card was 79.6% and 80.6%, respectively. Sensitivity of HiSens Auto TP and Mediace TPLA was 87.7% and 90.8%, respectively, and specificity was 99.5% and 99.0%, respectively. CONCLUSION: Despite the high concordance rate between TPLA and TPPA, there were negative TPLA results which were positive for both TPPA and FTA-ABS tests. Therefore, changing the primary donor screening test for syphilis from current TPPA to TPLA on the automated analyzer requires further investigation.

Prevalence of Hepatitis C Virus Infections and Distribution of Hepatitis C Virus Genotypes among Korean Blood Donors

BACKGROUND: Hepatitis C virus (HCV) remains a worldwide health-care burden. Prevalence rates vary and the distribution of genotypes depends on geographical location. Here, the recent prevalence of HCV infections and distribution of HCV genotypes among Korean blood donors were studied. METHODS: Between February 2005 and December 2009, a total of 11,064,532 donors were screened for anti-HCV and 11,412,690 donors were screened for HCV RNA. HCV genotyping was conducted for 748 blood donors with HCV RNA by using the line probe assay (VERSANT HCV Genotype 2.0 Assay, Bayer Healthcare, USA) after amplification of the 5'-untranslated and core regions of the genome. RESULTS: The anti-HCV prevalence was 0.16% (17,250/11,064,532). HCV RNA was detected in 959 out of the 11,412,690 donors (8.4/100,000). HCV RNA was more prevalent among women, donors who resided at harbor sites, and first-time donors. In addition, the prevalence of HCV RNA increased with age. The genotypes of 740 out of the 748 tested donors (98.9%) were identified. HCV genotype 1b (47.7%) and 2a/2c (35.0%) were dominant. Genotypes 2 (7.6%), 2b (2.3%), 3a (1.6%), 1a (1.3%), 1 (0.9%), 2v (0.5%), 1v (0.1%), and 3 (0.1%) were also identified. Genotype 4a/4c/4d (0.1%) was detected for the first time in one Korean blood donor. CONCLUSIONS: The distribution of HCV genotypes in Korea has not changed remarkably, with the exception of genotype 4a/4c/4d. A periodic study to monitor the prevalence of HCV infections and the distribution of HCV genotypes is required to identify emerging genotypes in Korea.

Analysis of Discarded Blood Components at a University Hospital in Korea / 대한수혈학회지

BACKGROUND: When it comes to wasting blood components, it usually means wastage before transfusion due to several reasons such as improvement of the patient's condition, death of the patient, delay of blood returning, etc. Yet blood components can sometimes can be wasted after a transfusion is started and this is referred as residual blood wastage. In this study, we analyzed the rate and causes of discarded blood components that are not used and the residual blood wastage in order to help reduce the rate of blood component wastage. METHODS: From January 2009 to December 2010, the number of and the reasons for discarded blood components without use and residual blood wastage were analyzed by reviewing the laboratory information system and wastage statements at Soonchunhyang University Seoul Hospital. RESULTS: The number of blood components issued during the study period was 24,001 units. Among them, the number of units discarded without use was 162 units (0.7%) and the number of units of residual blood wastage was 115 units (0.5%). Among the reasons for the discarded blood component without use, improvement of the patient's conditions ranked as 1st with 80 units (49.5%) and death of the patient ranked as 2nd with 42 units (25.9%). The biggest reason for the residual blood wastage was transfusion-related side effects with as many as 52 units (45.2%). Other than side effects, the wastage of residue from pediatric transfusion were 48 units (41.7%), followed by delay of surgery with 5 units (4.3%) and patients' refusal with 4 units (3.5%). CONCLUSION: The wastage of residue from pediatric transfusion was the second most common cause of residual blood wastage in our hospital. According to this, we should evaluate the routine use of pediatric transfusion bags and their cost-effectiveness in our hospital.

Experience of Use of the Automated Chemistry Analyzer Cobas(R) 6000 to Improve Work Flow of Emergency Chemistry Laboratory / 임상검사와정도관리

BACKGROUND: Soon Chun Hyang University Hospital emergency laboratory introduced Cobas(R) 6000 (Roche Diagnostics, Switzerland) to improve the turnaround time of emergency chemistry tests at peak time period. METHODS: For the designated period, before and after introduction of Cobas(R) 6000 the numbers of tests and test time were compared and we analyzed the process of the tests using Workflow simulator (Roche Diagnostics). RESULTS: The numbers of tests of 8 days (every Monday and Thursday) in June, 2007 and 2008 were 22,902 and 27,384. The mean test time of the 8 days in June, 2007 and 2008 were 13 min 41 sec and 12 min 22 sec. In 2007, increased mean test time was due to prolongation of waiting times in rotor within equipment for tests at peak time period. CONCLUSIONS: Using Cobas(R) 6000, the numbers of tests were increased at peak time period but mean test time was reduced, which made physicians and laboratory all satisfied.

Evaluation of OraQuick Advance Rapid HIV-1/2 Antibody Test as a Screening Test for HIV Infection / 대한임상미생물학회지

BACKGROUND: For the diagnosis of HIV infection, enzyme immunoassay (EIA) or chemiluminescence immunoassay (CLIA) is commonly used as a screening test. Although these methods have a high sensitivity and low cost, their high false positive rate can cause confusion in the patients and clinicians until a more specific test is done. OraQuick Advance Rapid HIV-1/2 Antibody Test (OraQuick) (OraSure Technologies, USA) is a rapid test that can detect HIV-1/2 antibodies in 20 minutes. It uses oral fluid, whole blood or serum sample. In this study, we evaluated the usefulness of the OraQuick as a screening and point-of-care test for HIV infection. METHODS: From Jan 2007 to Dec 2008, 45,276 samples referred to our laboratory were tested by CLIA method using the ADVIA Centaur (Bayer Healthcare LTD., USA) for HIV-1/2 antibody detection. Among them, 74 positive and 50 negative samples were tested by the Western immunoblot assay (WIB) and OraQuick test as a case-control study. Also, oral fluids from 30 HIV patients and 48 healthy persons were tested by OraQuick test. RESULTS: The sensitivity and specificity of OraQuick test (using serum samples) were 100% and 98.8% (95% confidence interval 96.9~100%), respectively. OraQuick tests (using oral fluid samples) were all positive for HIV patients but all negative for healthy persons. CONCLUSIONS: This study suggests that OraQuick can be used successfully as a rapid test for the early detection of HIV-1/2 antibody in patients visiting emergency departments and for the prevention of HIV infection in the health care providers.

A Case of Acute Myeloid Leukemia with Multilineage Dysplasia accompanying Malignant Pleural Effusion / 결핵및호흡기질환

We report a case of acute myeloid leukemia with multilineage dysplasia accompanying malignant pleural effusion. A 73 year-old male patient was admitted complaining of febrile sensations and right chest pain. The cytology of the pleural fluid revealed malignant pleural effusion showing many blasts, which had previously been identified in his bone marrow when he was diagnosed with acute myeloid leukemia with multilineage dysplasia two months earlier. His age and poor general condition had precluded chemotherapy with the exception of hydroxyurea and conservative treatment. Unfortunately, he succumbed to the disease 4.5 months after diagnosis. This case highlights the importance of determining if the pleural effusion of acute leukemia is malignant or not because it can suggest a pleural metastasis and influence the prognosis.

Utility of D-dimer Assay for Diagnosing Pulmonary Embolism: Single Institute Study / 대한진단검사의학회지

BACKGROUND: Pulmonary embolism (PE) presents with diverse non-specific signs and symptoms and its diagnosis mainly depends on diagnostic imaging tests which are laborious and not cost-effective, and only a small proportion of patients with suspected PE actually have the disease. The aim of this study was to analyze the utility of D-dimer test for diagnosing PE by categorizing patients into 'PE likely' and 'PE unlikely' groups using Wells score for clinical probability. METHODS: One hundred forty consecutive patients with clinically suspected PE, in whom D-dimer and imaging tests were performed were enrolled. Dignosis of PE was made when the imaging tests were positive. Wells scores were retrospectively assigned and the dignostic utility of D-dimer test was analyzed. RESULTS: Of the 140 patients studied, D-dimer test was positive in 97 and diagnostic imaging tests revealed PE, deep vein thrombosis (DVT), and PE+DVT in 24, 3, and 7 patients, respectively. For the diagnosis of PE, D-dimer test with cutoff value of > or =230 ng/mL showed sensitivity, specificity, and negative predictive value of 96.8%, 39.6%, and 97.7%, respectively. These values were 96.3%, 37.9%, and 91.7% in 'PE likely' group (n=56), and 100%, 38.8%, and 100% in 'PE unlikely' group (n=84). Among 43 patients with D-dimer values of <230 ng/mL, only one patient was diagnosed with PE, who belonged to the 'PE likely' group. CONCLUSIONS: D-dimer test cannot be used as a stand-alone test to diagnose PE, but it can be helpful for exclusion of PE especially in 'PE unlikely' group according to Wells score.

A Case of Therapy-Related Acute Monocytic Leukemia following Low-dose of Etoposide Treatment for Hemophagocytic Lymphohistiocytosis / 대한진단검사의학회지

We report a case of therapy-related acute myeloid leukemia after low-dosed topoisomerase II inhibitor (etoposide) treatment for hemophagocytic lymphohistiocytosis (HLH). A 62-yr-old female patient had previously been treated with a HLH-94 protocol containing a low-dose of etoposide (total dose of 300 mg/m2). Thirty-one months later, the patient was admitted to the hematology department with general weakness and upper respiratory infection symptoms. Peripheral blood smear and bone marrow study revealed acute monocytic leukemia. There was no evidence of myelodysplastic syndrome, and a cytogenetic study showed no chromosomal abnormalities.

Changes in airway eosinophils and bone marrow eosinophil progenitors following allergen-challenge in mouse model of asthma / 천식및알레르기

BACKGROUND: Eosinophilic airway inflammation is a characteristic feature of bronchial asthma. Recent studies showed that increased production and release of eosinophils from bone marrow(BM) might be the essential step in the development of eosinophilic airway inflammation. To testify the hypothesis that increase in BM eosinophil production may be an important determinant of the severity of airway eosinophilia, their relationship was studied in a mouse model of allergic airway inflammation. METHODS: BALB/c mice were sensitized with intraperitoneal ovalbumin adsorbed to aluminum potassium sulfate, followed by challenges with intranasal ovalbumin on two consecutive days. Saline was used for sensitization and challenge in control mice. Bronchoalveolar lavage(BAL) was performed at 24 h after last nasal challenge, immediately followed by BM cell harvest from the femurs. The severity of airway inflammation was assessed as BAL eosinophilia, and the capacity of BM eosinophil production was assessed as BM eosinophil colony forming units(Eo-CFUs) using a semisolid culture assay. RESULTS: There was a significant increase in the percentage of BAL eosinophils and lymphocytes with a resultant decrease in the percentage of alveolar macrophages in the ovalbumin- treated mice, compared with the saline-treated mice(p<0.05, respectively). Change in the percentage of neutrophils was not statistically significant. Compared with the saline-treated mice, the number of BM Eo-CFUs was significantly increased in the ovalbumin- treated mice(p<0.05). But the number of BM Eo-CFUs was not correlated significantly with the number of eosinophils in BAL fluid in the ovalbumin-treated mice. CONCLUSION: Respiratory exposure to allergen induced not only airway eosinophilia but also BM eosinophilopoiesis in this mice model of asthma. However there was no direct relationship between BM eosinophilopoiesis and airway eosinophilia, suggesting that the capacity of eosino-phil production in BM may not an important determinant of severity of airway eosinophilia.

A case of occupational asthma induced by terephthaloy1 chloride / 천식및알레르기

Terephthaloyl chloride, a chemical of low molecular weight, is used as an intermediate by a fabric manufacturing industry. It is known to cause gastrointestinal, respiratory and skin irritation. However, it has not been reported as a cause of occupational asthma till now. We report a case of occupational asthma caused by prolonged exposure to terephthaloyl chloride in the workplace. A 38 year-old man visited at the Allergy Clinic because of cough, dyspnea and wheezing for 5 years. He had worked at a factory for 15 years where he was involved in the process of manufacturing fabrics. At presentation, he had no symptoms and showed no abnormality on physical examination. When challenged with vapor of terephthaloyl chloride, he experienced sneezing and paroxysmal cough in a couple of minutes, followed by dyspnea and wheezing at 10 min. He also experienced urticarial rashes on the face and chest. The pulmonary function tests showed an atypical prolonged immediate airway response. PC20 methacholine decreased from 5 mg/ml to 0.79 mg/ml 24 hours after the challenge. Light microscopic examination of bronchial biopsies showed loss of epithelium, thickening of basement membrane, submucosal fibrosis, and increased inflammatory cell infiltration. The immediate drop in FEV1 and urticarial rash to terephthaloyl chloride suggests the possibility of an immediate hypersensitivity immune reaction. Further studies are needed to clarify the exact mechanism of terephthaloyl chloride induced asthma.

A Retrospective Study on the Potentially Fatal Asthma / 대한내과학회지

OBJECTIVES: A number of investigators have examined the possible pathophysiological mechanisms in patients who died from asthma, but the reasons for the increased incidence of death in patients with asthma are largely unknown. To elucidate the risk factors and possible causes of fatal asthma, we reviewed the clinical data of patients with potentially fatal asthma(PFA). METHODS: We retrospectively studied the clinical and laboratory profiles of 35 PFA patients(43 episodes) who had been admitted at the Kyungpook University Hospital and Taegu Fatima Hospital in recent 5 years(1989. 7-1994. 6). Our criteria of PFA were defined as either respiratory arrest or an arterial carbon dioxide tension(PaCO2) greater than 50 mmHg or an altered state of consciousness, due to acute asthma. RESULTS: 1) Twenty four patients with PFA were female and 11 male. At the time of PFA episode, age distribution was between 16-65 year (42% between 36-49). 2) Seasonal distribution was 13 episodes between March and May, 13 June and August, 6 September and November, 11 December and February. 3) Previous hospitalization history due to asthmatic attack was noted in 81 percent, and 75 percent were relatively compliant to their therapy. 5) At visiting emergency room, 81 percent satisfied the criteria of PFA, whereas 19 percent during hospitalizatoin. 77 percent required mechanical ventilation, and 52 percent of them within 30 minutes after visiting. 6) Initial arterial blood gas analysis at emergency room showed marked hypercapnia(75 +/- 29 mmHg), hypoxemia(50 +/- mmHg) and acidosis(pH 7.14 +/- 0.15). Serum potassium levels were within normal ranges in 75 percent. 7) All, except one, showed no significant cardiac arrthymias. 8) Possible precipitating factors leading to PFA were respiratory tract infection in 31 episodes, ingestion of NSAIDs in 2, emotional upsets in 2, irritant air pollutions in 2, withdrawal of anti-asthma drugs in 1, and unknown causes in 5. 9) Nine of 16 patients were atopic, and majority of them showed positive reaction to Dermatophagoides antigen. CONCLUSIONS: These results may suggest that PFA is mainly due to airway obstruction, and upper respiratory infection is an important precipitating factor leading to PFA. It is necessary to establish an appropriate plan for preventing PFA and related deaths.