Supine vs. prone chest CT in a COVID-19 patient during mechanical ventilation

A 72-year-old female patient with a history of ischaemic stroke, ocular myasthenia, arterial hyper-tension, and hypercholesterolaemia was admitted to the emergency department because of dyspnoea.
She reported having fever and cough for a week.
At admission, her pulse oximeter saturation was 84%, the tympanic temperature was 37.6 °C.
Laboratory findings revealed elevated C-reactive protein (19.69 mg/dL, normal range 0.01-0.5 mg/dL) and mild lymphopenia (0.7X10^3/mm^3, normal range 1.0-4.0 X10^3/mm^3).
The patient also underwent non-contrast chest CT.

The non-contrast chest CT performed at admission (Fig. 1) showed bilateral, symmetrical, sub-pleural ground-glass opacities (GGO), predominantly in the right lower lobe, with initial interlobular septal thickening (crazy-paving pattern).
There was no radiological evidence of pleural effusion or mediastinal lymphadenopathy.
These findings were highly suspicious for SARS-CoV-2 infection.
AP chest X-ray (Fig. 2) on day two from admission showed interval intubation, internal jugular vein CVC, nasogastric tube, and bilateral patchy airspace opacities.
A new chest CT scan (Figs. 3-5) was performed on day three of admission, in both supine and prone positions during mechanical ventilation.
Compared to the prior CT, the supine scan showed a significant increase in the extent and atten-uation of the opacities with pulmonary consolidation and atelectasis of the right lower lobe.
The prone scan showed a partial recovery of the aerated lung parenchyma in the right inferior lobe with a small area of residual consolidation in the posterior segment of the right lower lobe.

Background
COVID-19 is an infectious disease that causes mild symptoms in most people; however, some patients, especially those who have comorbidities and the elderly, can progress to pneumonia and acute respiratory distress syndrome (ARDS) [1,2].
Nevertheless, also healthy and young people can develop a severe illness as it happened in Northern Italy with ‘“patient 1’, a man in his 30s [3].

Clinical Perspective
Most patients affected by COVID-19 present primarily with fever, myalgia or fatigue, and
dry cough [1], others may not have clinical symptoms nor radiological abnormalities at presenta-tion [4].
At present, the RT-PCR test is the gold standard for the final diagnosis of COVID-19 [5], even if it is burdened by a false negative rate.
Patients who progress to ARDS and multi-organ failure could benefit from methylprednisolone to decrease the risk of death [6].
In patients with severe ARDS, prone ventilation has been demonstrated to improve oxygenation and respiratory compliance compared to supine positioning [7].

Imaging Perspective
Chest CT scan could be useful for diagnosis of COVID-19 in highly suspected patients, but it should not be used for screening or early diagnosis because of its low specificity that does not allow differentiation between COVID-19 pneumonia and other cases of infection [8].
Chest CT has a role in the follow-up of patients until complete recovery [9].
Patients who develop respiratory deterioration and instability can benefit from lung ultrasonogra-phy that is more sensitive than chest X-ray for evaluation of pneumonia and
ARDS [10].
CT scan in supine and prone position allows to investigate the modification in lung morphology with changes in body position, and leads to a description in vivo of the lung pathology in ARDS.

Outcome
Since admission, the patient was given antiviral treatment based on lopinavir/ritonavir. Due to the rapidity of respiratory deterioration, she however was transferred to the intensive care unit where she underwent invasive mechanical ventilation.
Meanwhile, laboratory testing for SARS-CoV-2 returned positive.
The patient is currently in the intensive care unit and her clinical condition is stable.

Take-home Message
Patients that develop ARDS require a big effort to adjust the ventilatory strategy. [11]
The chest CT has a great impact on therapeutic strategy since it allows to guide response to a prone position and for making decisions related to weaning the patient form ventilatory support.
The addition of a prone scan may be useful to identify the most efficacious strategy for the venti-lation of these patients.

Written informed patient consent for publication has been obtained.