Exploring the association between happy hypoxia and Coronavirus disease 2019 in the triage phase
Creators: name: Kaga, Mihiro
name: Sasaki, Masanao
name: Masuda, Takahiro
name: Sato, Hiroyuki
name: Ueda, Takeshi
name: Hirakawa, Akihiro
Publisher: name: Taylor & Francis
Year: 2025
Subjects: subject: Medicine
subject: Cell Biology
subject: Biotechnology
subject: Immunology
subject: FOS: Clinical medicine
subject: Marine Biology
subject: Cancer
subject: Science Policy
subject: Mental Health

description: Patients with severe coronavirus disease 2019 (COVID-19) have been reported to show hypoxia without displaying typical clinical signs or symptoms, called “happy hypoxia.” To explore the potential of happy hypoxia as a distinctive symptom of COVID-19, we compared vital signs in the triage phase between patients with and without COVID-19. We retrospectively identified emergency patients with and without COVID-19 admitted to Rakuwakai Marutamachi Hospital, Kyoto, Japan, between January 2021 and December 2021. 317 patients were analyzed. Multivariate logistic regression analysis, including all vital signs, demonstrated that the respiratory rate was not statistically associated with COVID-19 (odds ratio, 0.94, p = 0.058), suggesting that happy hypoxia may not be a distinct hallmark of COVID-19. This study examined a phenomenon referred to as “happy hypoxia,” in which patients with severe coronavirus disease 2019 (COVID-19) exhibit low oxygen levels without the typical signs of distress, such as rapid breathing. Our objective was to determine whether happy hypoxia is a distinct symptom of COVID-19 compared to patients with other medical conditions.We analyzed data from 317 patients treated at a hospital in Kyoto, Japan, during 2021. Our findings revealed that the breathing rates of patients with COVID-19 were comparable to those of patients who did not have COVID-19, suggesting that happy hypoxia may not serve as a reliable indicator of COVID-19.In conclusion, this research highlights that relying solely on breathing rates during initial assessments in emergency situations may not effectively identify COVID-19. Understanding these findings can enhance how healthcare providers triage and manage patients. Patients with severe coronavirus disease 2019 (COVID-19) have occasionally exhibited hypoxia without displaying typical clinical signs or symptoms, called “happy hypoxia.” However, there is no evidence that has investigated the relationship between “happy hypoxia” and COVID-19 by analyzing vital signs in triage settings. This study is the first clinical research that demonstrated the respiratory rates during the triage phase in patients with COVID-19 were not markedly different from those in patients with other diseases. Happy hypoxia may not be a clear characteristic of COVID-19. Happy hypoxia, characterized by severe hypoxia without an increase in respiratory rate, was investigated as a potential distinctive symptom of severe coronavirus disease 2019 (COVID-19). This study retrospectively analyzed 317 patients with respiratory failure, comparing those infected with COVID-19 to those with other conditions at Rakuwakai Marutamachi Hospital in 2021. Multivariate logistic regression analyses indicated that respiratory rates in patients with COVID-19 did not significantly differ from those of other patients. The inclusion of respiratory rates in the diagnostic models did not notably enhance COVID-19 diagnosis during the triage phase, as assessed through receiver operating characteristic analysis. No significant difference was observed in the correlation coefficient between the percutaneous oxygen/inspired oxygen (SpO2/FiO2) ratio and respiratory rate between COVID-19 and non-COVID-19 patients. The results indicate that happy hypoxia may not be a distinct hallmark of COVID-19, and that the respiratory rate has limited utility in triage decisions.