IntroductionParticulate matter and air pollution in Korea are becoming worse. There is a lack of research regarding the impact of particulate matter on patients with COPD. Therefore, the purpose of this study was to investigate the effects of various air pollution factors, including particulate matter, on the incidence rate of severe acute exacerbations of COPD (AECOPD) events.MethodsWe analyzed the relationship between air pollutants and AECOPD events that required hospitalization at Guro Hospital in Korea from January 1, 2015 to May 31, 2017. We used general linear models with Poisson distribution and log-transformation to obtain adjusted relative risk (RR). We conducted further analysis through the Comprehensive Air-quality Index (CAI) that is used in Korea.ResultsAmong various other air pollutants, particulate matter was identified as a major source of air pollution in Korea. When the CAI score was over 50, the incidence rate of severe AECOPD events was statistically significantly higher [RR 1.612, 95% CI, 1.065–2.440, P=0.024]. Additionally, the particulate matter levels 3 days before hospitalization were statistically significant [RR 1.003, 95% CI, 1.001–1.005, P=0.006].ConclusionParticulate matter and air pollution increase the incidence rate of severe AECOPD events. COPD patients should be cautioned against outdoor activities when particulate matter levels are high.

Background The high transmission and fatality rates of coronavirus disease 2019 (COVID-19) strain intensive care resources and affect the treatment and prognosis of critically ill patients without COVID-19. Therefore, this study evaluated the differences in characteristics, clinical course, and prognosis of critically ill medical patients without COVID-19 before and during the COVID-19 pandemic. Methods This retrospective cohort study included patients from three university-affiliated tertiary hospitals. Demographic data and data on the severity, clinical course, and prognosis of medical patients without COVID-19 admitted to the intensive care unit (ICU) via the emergency room (ER) before (from January 1 to May 31, 2019) and during (from January 1 to May 31, 2021) the COVID-19 pandemic were obtained from electronic medical records. Propensity score matching was performed to compare hospital mortality between patients before and during the pandemic. Results This study enrolled 1161 patients (619 before and 542 during the pandemic). During the COVID-19 pandemic, the Simplified Acute Physiology Score (SAPS) 3 and Sequential Organ Failure Assessment (SOFA) scores, assessed upon ER and ICU admission, were significantly higher than those before the pandemic (p < 0.05). The lengths of stay in the ER, ICU, and hospital were also longer (p < 0.05). Finally, the hospital mortality rates were higher during the pandemic than before (215 [39.7%] vs. 176 [28.4%], p < 0.001). However, in the propensity score-matched patients, hospital mortality did not differ between the groups (p = 0.138). The COVID-19 pandemic did not increase the risk of hospital mortality (odds ratio [OR] 1.405, 95% confidence interval [CI], 0.937–2.107, p = 0.100). SAPS 3, SOFA score, and do-not-resuscitate orders increased the risk of in-hospital mortality in the multivariate logistic regression model. Conclusions In propensity score-matched patients with similarly severe conditions, hospital mortality before and during the COVID-19 pandemic did not differ significantly. However, hospital mortality was higher during the COVID-19 pandemic in unmatched patients in more severe conditions. These findings imply collateral damage to non-COVID-19 patients due to shortages in medical resources during the COVID-19 pandemic. Thus, strategic management of medical resources is required to avoid these consequences.

Nonpharmaceutical interventions (e.g., social distancing) are recommended to prevent the spread of respiratory viruses. However, few epidemiological studies have assessed whether social distancing in actual settings reduces the disease burden of severe acute respiratory infections (SARIs) in the general population. Accordingly, we aimed to assess associations between nationwide social distancing for coronavirus disease 2019 (COVID-19) and non-COVID-19 SARIs. We collected data on SARI epidemiologic characteristics recorded from January 2018 through December 2020 from the nationwide sentinel SARI surveillance data maintained by the Korea Disease Control and Prevention Agency. The number of SARIs per 1000 hospitalized patients decreased significantly to 18.61, 18.15, and 6.25 in 2018, 2019, and 2020 ( p <0.001), respectively, during the surveillance period of 3 years. The number of intensive care unit admissions associated with SARIs per 1000 hospitalized patients was 0.83, 0.69, and 0.54 in 2018, 2019, and 2020 ( p <0.001), respectively, and the number of SARI-associated mortalities per 1000 patients was 0.42, 0.29, and 0.27 in 2018, 2019, and 2020 ( p <0.001), respectively. Moreover, SARIs had two peak seasons in 2 years of the surveillance period (2018 and 2019). However, seasonality was not observed since social distancing was initiated. Our sentinel surveillance data demonstrated a remarkable reduction in SARI disease burden and a change in seasonality following the implementation of nationwide social distancing. Accordingly, we suggest that social distancing could be effective in forthcoming seasonal epidemics of non-COVID19 origin, although the impact thereof on other aspects of society needs to be carefully considered.

BACKGROUND: The use of high-flow nasal cannula (HFNC) is rapidly increasing without clear indications, creating the potential for overuse or misuse and the accompanying risk of adverse events. The purpose of this study was to determine the factors associated with HFNC failure by examining the current clinical practice of HFNC. METHODS: From July 1, 2017, to June 30, 2018, in 5 university-affiliated hospitals in the Republic of Korea, a total of 1,161 admitted adult subjects who had HFNC administered were retrospectively enrolled and their medical records were reviewed. RESULTS: Pulmonary diseases including pneumonia (n 5 757, 65.2%) were the most common reason for use of HFNC. Subjects with do-not-resuscitate (DNR) or do-not-intubate (DNI) orders comprised 33.8% of the study population (n 5 392); 563 subjects (48.5%) were escalated directly to HFNC from low-flow devices without applying reservoir or other high-flow devices. In the non-DNR/DNI subjects, arterial blood gas was not monitored in 15.2% and 14.8% of subjects before and after HFNC application, respectively, and it was not monitored in 28.0% just before HFNC weaning. The HFNC failure rate was 27.0% in non-DNR/DNI subjects, and the HFNC failure was significantly associated with the decision by residents to apply HFNC (odds ratio [OR] 2.03, 95% CI 1.29-3.18, P 5 .002), high breathing frequency (OR 1.07, 95% CI 1.04-1.10, P < .001) 6 h before HFNC application, low S aO 2 (OR 0.92, 95% CI 0.89-0.95, P < .001)^6 h before HFNC application, low S pO 2 (OR 0.95, 95% CI 0.93-0.98, P < .001)^6 h before HFNC application, and the ratio of S pO 2 /F IO 2 to breathing frequency (ROX index)^6 h after HFNC application (OR 0.88, 95% CI 0.84-0.92, P < .001). CONCLUSIONS: HFNC was practiced without applying reservoir or other high-flow devices before application and without appropriate arterial blood gas monitoring during HFNC therapy. HFNC failure was significantly associated with the decision by the resident to use HFNC, breathing frequency, S aO 2 , and S pO 2^6 h before HFNC application, and with the ROX index^6 h after HFNC application.

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