Discussion
Spontaneous pneumothorax is believed to be caused by the rupture of
alveoli, although the precise cause is unknown. It may be a direct
rupture or via the mediastinum4. In secondary
spontaneous pneumothorax, weakness of the alveoli due to emphysema or
necrotic pneumonia can be a cause of pneumothorax5.
Acute respiratory distress syndrome is also a cause of secondary
pneumothorax6 in addition to mechanical ventilation.
Among COVID-19 patients, 1%-2% had pneumothorax7,8.
Zantah reported six patients with pneumothorax, and four of them were
under mechanical ventilation9. Martinelli reported 38
patients with invasive ventilatory support among 71 patients with
pneumothorax10.
At our institute, the incidence of pneumothorax was 0.75% (8/1061).
Patients in this hospital were not ventilated in principle because of
divided hospital function in moderately ill patients, as per the policy
of the prefectural government. We did not use NPPV for infection
control. None of the patients with pneumothorax used HFNC; therefore, we
can exclude the influence of barotrauma. Alternatively, the main cause
of the pneumothorax could be alveolar weakness, as all patients except
one young woman were over 80 years of age, and due to the high rate of
steroid use (75%) and alveolar injury due to pneumonia. The limitation
of this study is the small number of patients with pneumothorax in
single institution, due to which we could not identify the risk factors
of pneumothorax.
In acute Middle East respiratory syndrome, pneumothorax is associated
with a poor prognosis11. Martinelli et al. reported
that the mortality rate of COVID-19 was significantly higher in patients
over 70 years of age than in those < 70 years of
age10. At our institute, the overall mortality was
7.26% (77/1061), and that of patients over 80 years of age was 18.3%
(61/334). The mortality rate of patients with pneumothorax over 80 years
of age was as high as 85.7% (6/7). In conclusion,
although pneumothorax is a rare
complication, it can be a predictive factor of poor prognosis in elderly
patients with COVID-19. Further studies including autopsy is required to
clarify the relation between pneumothorax, COVID- 19, and underlying
diseases.
Acknowledgements
We are grateful to Mr. Kenta Ebisawa who managed this temporary field
hospital, and all past and present workers.
Disclosure
Approval of the research protocol: This retrospective study was approved
by the ethics committee of Shonan Kamakura General Hospital.
Informed consent: The requirement
for obtaining informed consent from patients was waived due to the
retrospective nature of the study. Patients were allowed to withdraw
from the study whenever they wished.
Registry and the registration no. of the study: N/A
Animal studies: N/A
Conflict of interest: None
Author Contributions: JK contributed to writing article; HK, YA, TK, HY,
and SH contributed to conception and revision of article; CI, RS, NI,
KM, TM, TN, YS, and YI contributed to data collection and patient care;
and RF and HK contributed to manuscript review.
Data Sharing and Data Accessibility:
The data that support the findings of this study are available from the
corresponding author upon reasonable request.
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Table 1 Clinical features of pneumothorax patients in coronavirus
disease