Computerised tomography (CT) in severe acute respiratory syndrome (SARS): late-stage acute respiratory disease syndrome (ARDS) and follow-up findings

Introduction

SARS is caused by a newly described coronavirus [1]. About 20% of SARS patients require oxygen supplementation and mechanical ventilation in an ICU for respiratory failure and ARDS [2]. We aim to describe the CT findings of patients in the late stage of ARDS caused by SARS, and report changes on long-term follow-up.

Methods

A retrospective review of CT findings in eight patients who met CDC criteria for SARS. All patients met criteria for ARDS [3]. CT was performed in late-stage ARDS (more than 2 weeks after onset of ARDS) [4], and after discharge from hospital in survivors. Relevant respiratory and ventilatory parameters, total steroid dose and outcome were recorded.

Results

All mechanically ventilated patients received low pressure (peak pressure < 30–35 mmHg), low volume (tidal volume < 8 ml/kg estimated lean body mass) ventilation [5]. Five patients received prolonged mechanical ventilation (over 14 days), one was only ventilated for 72 hours, and two patients were not ventilated at all. All patients received high-dose pulse methylprednisolone (2.5–7 g total dose). Three patients died and five survived to hospital discharge.

ARDS chronic stage CT findings

Consolidation was present in five patients. Ground glass opacification and interstitial thickening were present in all patients. Three had evidence of fibrosis. Small pulmonary cysts were present in five patients and extrapulmonary gas (pneumothorax) in two. Findings in patients after long-term mechanical ventilation (more than 14 days) and short-term or no ventilation were similar. At follow-up CT (mean 3 months, n = 4), consolidation and extrapulmonary gas had resolved, ground glass opacification improved, but signs of fibrosis had generally progressed.

Conclusion

The CT features of late-stage ARDS caused by SARS are similar to those seen in late-stage ARDS from other causes [4], with no apparent differences between patients who received prolonged mechanical ventilation and those who did not. Fibrotic changes seen in the chronic phase of ARDS do not seem to resolve significantly after discharge.