Histopathological features in fatal COVID-19 acute respiratory distress syndrome

Med Intensiva (Engl Ed). 2021 Jun-Jul;45(5):261-270. doi: 10.1016/j.medin.2021.02.007. Epub 2021 Feb 27.

Abstract
in English, Spanish

Background: COVID-19 acute respiratory distress syndrome (ARDS) shares the common histological hallmarks with other forms of ARDS. However, the chronology of the histological lesions has not been well established.

Objective: To describe the chronological histopathological alterations in the lungs of patients with COVID-19 related ARDS.

Design: A prospective cohort study was carried out.

Setting: Intensive Care Unit of a tertiary hospital.

Patients: The first 22 consecutive COVID-19 deaths.

Measurements: Lung biopsies and histopathological analyses were performed in deceased patients with COVID-19 related ARDS. Clinical data and patient course were evaluated.

Results: The median patient age was 66 [63-74] years; 73% were males. The median duration of mechanical ventilation was 17 [8-24] days. COVID-19 induced pulmonary injury was characterized by an exudative phase in the first week of the disease, followed by a proliferative/organizing phase in the second and third weeks, and finally an end-stage fibrosis phase after the third week. Viral RNA and proteins were detected in pneumocytes and macrophages in a very early stage of the disease, and were no longer detected after the second week.

Limitation: Limited sample size.

Conclusions: The chronological evolution of COVID-19 lung histopathological lesions seems to be similar to that seen in other forms of ARDS. In particular, lung lesions consistent with potentially corticosteroid-sensitive lesions are seen.

Antecedentes: El síndrome de dificultad respiratoria aguda (SDRA) asociado a la COVID-19 comparte características histológicas con otros tipos de SDRA. Sin embargo, no se ha establecido adecuadamente la cronología de las lesiones histológicas.

Objetivo: Describir las alteraciones histopatológicas cronológicas en los pulmones de los pacientes con síndrome de dificultad respiratoria aguda asociado a COVID-19.

Diseño: Estudio prospectivo de cohortes.

Ámbito: Unidad de cuidados intensivos de un hospital terciario.

Pacientes: Las primeras 22 muertes consecutivas por COVID-19.

Intervenciones: Se llevaron a cabo biopsias pulmonares y análisis histopatológicos en pacientes fallecidos por SDRA asociado a COVID-19. Se evaluaron los datos clínicos y la evolución médica.

Resultados: La mediana de edad de los pacientes fue de 66 (63-74) años y el 73% eran varones. La mediana de la duración de la ventilación mecánica fue de 17 (8-24) días. La lesión pulmonar inducida por COVID-19 se caracterizó por una fase exudativa durante la primera semana de la enfermedad, seguida de una fase proliferativa/organizativa en la segunda y tercera semana y, por último, una fase de fibrosis en fase terminal tras la tercera semana de evolución. Se detectaron proteínas y ARN vírico en neumocitos y macrófagos en una fase muy temprana de la enfermedad, pero estos ya no se volvieron a detectar a partir de la segunda semana.

Limitación: Tamaño limitado de la muestra.

Conclusión: La evolución cronológica de las lesiones histopatológicas pulmonares asociadas a la COVID-19 parece ser similar a la de otras formas de SDRA. En particular, se observan daños pulmonares coherentes con las lesiones potencialmente sensibles a los corticosteroides.

Keywords: ACE2, angiotensin-converting enzyme 2; AFOP, acute fibrinous and organizing pneumonia; ARDS, acute respiratory distress syndrome; COVID-19; COVID-19 related acute respiratory distress syndrome; COVID-19, coronavirus infectious disease; DAD, diffuse alveolar damage; HE, hematoxylin–eosin; Histopathology; ISH, in situ hybridization; NMBD, neuromuscular blocking drugs; RT-PCR, Reverse Transcriptase-Polymerase chain reaction; SAPSII, simplified acute physiology score; SARS-CoV-2; SOFA, Sequential Organ Failure Assessment; VILI, ventilator induced lung injury.

Publication types

  • Research Support, Non-U.S. Gov't