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BACKGROUND: Persistent impairment of pulmonary function and exercise capacity has been known to last for months or even years in the survivors who recovered from other coronavirus pneumonia. Some reports showed that subjects with coronavirus disease 2019 pneumonia after being discharged could have several sequelae, but there are few studies on gas exchange and exercise capacity complications in these subjects. AIMS: To describe residual gas exchange abnormalities during recovery from coronavirus disease 2019 pneumonia. METHODS: In an observational study, 90 d after onset of disease, we scheduled almost 200 subjects for an outpatient visit with pulmonary function testing and computed tomography of the lungs. Lung mechanics by using body plethysmography, gas exchange with diffusing lung capacity for carbon monoxide determined by the single-breath technique (D LCOsb ) and diffusing lung capacity for nitric oxide determined by the single-breath technique (D LNOsb ), and exercise ability by using the 6-min walk test (6MWT) were measured in the subjects. The results were compared between those who required invasive mechanical ventilation and those who did not. RESULTS: A total of 171 subjects were included, the majority (96%) had signs of residual pneumonia (such as an excess of high attenuation areas) on computed tomography of the lungs. The D LCOSB results were below the lower limit of the normal range in 29.2% of the subjects; during the 6MWT, 67% experienced oxygen desaturation (S pO 2 ) > 4%; and, in 81 (47%), the dropped below 88%. Subjects who required invasive mechanical ventilation (49.7%) were more likely to have lower lung volumes, more gas exchange abnormality, less exercise capacity and more radiologic abnormality. CONCLUSIONS: Subjects who recovered from severe COVID-19 pneumonia continued to have abnormal lung function and abnormal radiologic findings.

COVID-19 es la enfermedad causada por el virus SARS-CoV-2, la cual ha ocasionado una pandemia sin precedentes, con gran cantidad de infectados y muertos en el mundo. Aunque la mayoría de los casos son leves, existe una cantidad considerable de pacientes que desarrollan neumonía o, incluso, síndrome de distrés respiratorio agudo (SDRA). Luego de recuperarse del cuadro inicial, muchos pacientes continúan con diversos síntomas (fatiga, tos seca, fiebre, disnea, anosmia, dolor torácico, entre otras), lo que ha llevado a considerar la posible existencia del “síndrome pos-COVID-19”. Aunque la definición y validez de este síndrome aún no son claras, varios estudios reportan que los individuos recuperados de la COVID-19 pueden tener persistencia de síntomas, anormalidades radiológicas y compromiso en la función respiratoria. La evidencia actual sugiere que existe gran cantidad de secuelas pulmonares despues de una neumonía por COVID-19 (engrosamiento intersticial, infiltrado en vidrio esmerilado, patrón en empedrado, bronquiectasias, entre otras.). De igual forma, parece ser que las pruebas de función pulmonar (espirometría, prueba de difusión pulmonar de monóxido de carbono, prueba de caminata de seis minutos y la medición de las presiones respiratorias máximas), además de la tomografía axial computarizada de alta resolución, son útiles para evaluar las secuelas pulmonares pos-COVID-19. En esta revisión se pretende describir las posibles secuelas a nivel pulmonar posteriores a neumonía por COVID-19, así como sugerir procedimientos diagnósticos para su correcta evaluación y seguimiento, que permitan el manejo adecuado por parte de un equipo médico multidisciplinario.

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