Platypnea-orthodeoxia syndrome (POS) is a rare clinical syndrome characterized by orthostatic oxygen desaturation and positional dyspnea from supine to an upright position. We observed POS in 5 of 20 cases of severe 2019 novel coronavirus (COVID-19) pneumonia, which demonstrated persistently elevated shunt fraction even after liberation from mechanical ventilation. POS was first observed during physiotherapy sessions; median oxygen desaturation was 8 % (range: 8–12 %). Affected individuals were older (median 64 vs 53 years old, p = 0.05) and had lower body mass index (median 24.7 vs 27.6 kg/m², p = 0.03) compared to those without POS. While POS caused alarm and reduced tolerance to therapy, this phenomenon resolved over a median of 17 days with improvement of parenchymal disease. The mechanisms of POS are likely due to gravitational redistribution of pulmonary blood flow resulting in increased basal physiological shunting and upper zone dead space ventilation due to the predominantly basal distribution of consolidative change and reported vasculoplegia and microthrombi in severe COVID-19 disease.

鸭嘴兽正畸综合症（POS）是一种罕见的临床综合征，其特征是体位性氧饱和度下降和从仰卧位到直立位的呼吸困难。我们在20例严重的2019年新型冠状病毒（COVID-19）肺炎病例中有5例观察到POS，即使从机械通气中解放出来后，其分流分数仍持续升高。POS是在理疗期间首次观察到的；氧饱和度中位数为8％（范围：8–12％）。受影响的个体年龄较大（中位年龄为64岁，相对于53岁，p  = 0.05），体重指数较低（中位年龄为24.7 vs 27.6 kg / m ²，p = 0.03），而没有POS的则为0.03。尽管POS引起了警觉并降低了对治疗的耐受性，但这种现象在中位疾病改善后的17天中值得以解决。POS的机制很可能是由于肺血流的重力重新分布，导致了基础生理分流增加以及上部区域死区通气，这是由于合并基础变化的主要基础分布以及在严重的COVID-19疾病中报告了血管麻痹和微血栓。