Background

An intriguing feature recently unveiled in some COVID-19 patients is the “silent hypoxemia” phenomenon, which refers to the discrepancy of subjective well-being sensation while suffering hypoxia, manifested as the absence of dyspnea.

Objective

To describe the clinical characteristics and predictors of silent hypoxemia in hospitalized COVID-19 patients.

Methods

We conducted a prospective cohort study including consecutive hospitalized adult (≥ 18 years) patients with confirmed COVID-19 presenting to the emergency department with oxygen saturation (SpO2) ≤ 80% on room air from March 15 to June 30, 2020. We analyzed the characteristics, disease severity, and in-hospital outcomes of patients presenting with dyspnea and those without dyspnea (silent hypoxemia).

Results

We studied 470 cases (64.4% men; median age 55 years, interquartile range 46–64). There were 447 (95.1%) patients with dyspnea and 23 (4.9%) with silent hypoxemia. The demographic and clinical characteristics, comorbidities, laboratory and imaging findings, disease severity, and outcomes were similar between groups. Higher breathing and heart rates correlated significantly with lower SpO₂ in patients with dyspnea but not in those with silent hypoxemia. Independent predictors of silent hypoxemia were the presence of new-onset headache (OR 2.919, 95% CI 1.101–7.742; P = 0.031) and presenting to the emergency department within the first eight days after symptoms onset (OR 3.183, 95% CI 1.024–9.89; P = 0.045).

Conclusions

Patients with silent hypoxemia sought medical attention earlier and had new-onset headache more often. They were also likely to display lower hemodynamic compensatory responses to hypoxemia, which may underestimate the disease severity.

中文翻译：

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一组住院 COVID-19 患者无症状低氧血症的特征和预测因子

背景

最近在一些 COVID-19 患者中发现的一个有趣特征是“无声低氧血症”现象，它是指在缺氧时主观幸福感的差异，表现为没有呼吸困难。

客观的

描述住院 COVID-19 患者无症状低氧血症的临床特征和预测因素。

方法

我们进行了一项前瞻性队列研究，纳入了 2020 年 3 月 15 日至 6 月 30 日在室内空气中氧饱和度 (SpO2) ≤ 80% 的连续住院成人（≥ 18 岁）确诊 COVID-19 的患者。我们分析了出现呼吸困难和无呼吸困难（无症状低氧血症）患者的特征、疾病严重程度和住院结局。

结果

我们研究了 470 个病例（64.4% 为男性；中位年龄 55 岁，四分位数范围 46-64）。有 447 名 (95.1%) 患者出现呼吸困难，23 名 (4.9%) 患者出现无症状低氧血症。两组间的人口统计学和临床​​特征、合并症、实验室和影像学检查结果、疾病严重程度和结果相似。较高的呼吸和心率与呼吸困难患者较低的 SpO ₂显着相关，但与无症状低氧血症患者无关。无症状低氧血症的独立预测因素是出现新发头痛（OR 2.919，95% CI 1.101–7.742；P  = 0.031）并在症状出现后的前八天内到急诊室就诊（OR 3.183，95% CI 1.024 –9.89；P  = 0.045）。

结论

无症状低氧血症患者更早就医，并且更常出现新发头痛。他们也可能对低氧血症表现出较低的血液动力学代偿反应，这可能低估了疾病的严重程度。