Seward J B, Hayes D L, Smith H C, Williams D E, Rosenow E C, Reeder G S, Piehler J M, Tajik A J
Mayo Clin Proc. 1984 Apr;59(4):221-31. doi: 10.1016/s0025-6196(12)61253-1.
Platypnea-orthodeoxia is a rare and poorly understood syndrome of orthostatic accentuation of a right-to-left shunt, usually across a patent foramen ovale. The syndrome is most commonly recognized in patients with a history of a major pulmonary disorder such as pneumonectomy, recurrent pulmonary emboli, or chronic lung disease. Pulmonary artery pressures are typically normal. The physiologic mechanism is unknown. We recommend that initial assessment consist of measurement of blood gases with the patient in the supine and upright positions. Orthostatic desaturation should prompt further investigation. A definitive diagnosis can most easily be obtained by tilt-table two-dimensional echocardiography with peripheral venous contrast medium. The shunt can be localized at the atrial level and directly visualized and semiquantitated. The decision about surgical closure of the patent foramen ovale is based on the degree of clinical disability. Because a significant shunt is manifest only in the upright position, astute clinical suspicion is of paramount importance for proper diagnosis. Increased awareness of this syndrome and ease of echocardiographic diagnosis will facilitate recognition of this potentially treatable cause of orthostatic hypoxia.
平卧呼吸困难-直立性低氧血症是一种罕见且了解甚少的综合征，表现为右向左分流的体位性加重，通常是通过未闭的卵圆孔。该综合征最常见于有重大肺部疾病史的患者，如肺切除术、复发性肺栓塞或慢性肺病。肺动脉压力通常正常。其生理机制尚不清楚。我们建议初始评估包括在患者仰卧位和直立位时测量血气。直立性血氧饱和度降低应促使进一步检查。通过倾斜台二维超声心动图结合外周静脉造影剂最容易获得明确诊断。分流可定位在心房水平，并可直接可视化和半定量。关于未闭卵圆孔手术闭合的决定基于临床残疾程度。由于显著分流仅在直立位时出现，敏锐的临床怀疑对于正确诊断至关重要。对该综合征认识的提高以及超声心动图诊断的便利性将有助于识别这种潜在可治疗的直立性缺氧原因。
