Background: In Coronavirus disease 2019 (COVID-19), some patients have low oxygen saturation without any dyspnea. This has been termed "happy hypoxia." No worldwide prevalence survey of this phenomenon has been conducted. This review aimed to summarize information on the prevalence, risk factors, and outcomes of patients with happy hypoxia to improve their management.
Methods: We conducted a systematic search of electronic databases for all studies published up to April 30, 2022. We included high-quality studies using the Newcastle-Ottawa Scale (NOS) tool for qualitative assessment of searches. The prevalence of happy hypoxia, as well as the mortality rate of patients with happy hypoxia, were estimated by pooled analysis and heterogeneity by I2.
Results: Of the 25,086 COVID-19 patients from the 7 studies, the prevalence of happy hypoxia ranged from 4.8 to 65%. The pooled prevalence was 6%. Happy hypoxia was associated with age > 65 years, male sex, body mass index (BMI)> 25 kg/m2, smoking, chronic obstructive pulmonary disease, diabetes mellitus, high respiratory rate, and high d-dimer. Mortality ranged from 01 to 45.4%. The pooled mortality was 2%. In 2 studies, patients with dyspnea were admitted to intensive care more often than those with happy hypoxia. One study reported that the length of stay in intensive care did not differ between patients with dyspnea and those with happy hypoxia at admission. One study reported the need for extracorporeal membrane oxygenation (ECMO) in patients with happy hypoxia.
Conclusion: The pooled prevalence and mortality of patients with happy hypoxia were not very high. Happy hypoxia was associated with advanced age and comorbidities. Some patients were admitted to the intensive care unit, although fewer than dyspneic patients. Its early detection and management should improve the prognosis.
Keywords: COVID −19; happy hypoxia; outcomes; prevalence.
© 2022 Bepouka et al.