ABSTRACT
Platypnea-orthodeoxia syndrome (POS) is a rare disorder associated with coronavirus disease 2019 (COVID-19) pneumonia. However, POS may be underdiagnosed. We report the case of a 59-year-old female patient with POS complicated by pulmonary embolism in COVID-19. Imaging revealed ground-glass opacities predominantly in the lower lobes and a pulmonary embolus in the right upper lobe. She was diagnosed with POS due to marked postural discrepancies between supine and upright oxygen saturations and blood oxygenation. Intracardiac shunt, one of the etiologies of POS, was not detected by bubble contrast echocardiography, and postural de-saturation gradually improved with methylprednisolone and edoxaban administration. In our literature review, only 3 of the 16 patients with POS associated with COVID-19 had cardiac shunting, suggesting that moderate to severe COVID-19 causes POS without cardiac shunts. COVID-19-associated vasculopathy and lower lung lesion predominance in COVID-19 pneumonia may cause ventilation-perfusion mismatch due to gravitational shunting of blood into the poorly ventilated lower lungs in the upright position, which may ultimately cause POS. Hypoxemia impedes rehabilitation, whereas early initiation of supine positioning in bed, with knowledge of the pathophysiology of POS, may have a positive effect.
ABSTRACT
BACKGROUND: The longitudinal observation of the detection of antibody responses to SARS-CoV-2 using antibody kits during the clinical course of COVID-19 is not yet fully investigated. OBJECTIVES: To understand the significance of the detection of anti-SARS-CoV-2 antibodies, particularly IgG, using a rapid antibody kit, during the clinical course of COVID-19 patients with different severities. METHODS: Sixty-three serum samples from 18 patients (5 asymptomatic and 13 symptomatic patients) were retrospectively examined using a commercial SARS-CoV-2 IgM/IgG antibody kit. PCR positivity of patient samples was also examined as a marker of current SARS-CoV-2 infection. RESULTS: IgG antibodies were detected in all cases in this study. The IgG detection rates reached 100.0% in samples collected on day 13 or later. IgG seropositivity after an initial negative status was observed in 13 patients (3/5 asymptomatic and 10/13 symptomatic cases). Interestingly, the persistence of both PCR and IgG positivity was detected in seven cases, of which three were asymptomatic. The longest overlap duration of the PCR and IgG positivity was 17 days in asymptomatic status. CONCLUSIONS: SARS-CoV-2-specific IgG production can be detected in all infected individuals, using a rapid antibody kit, irrespective of clinical status. However, these findings suggest that, in some infected individuals, particularly those with asymptomatic status, the presence of virus-specific IgG antibodies does not imply prompt viral clearance.