High Resolution Computed Tomography of Thorax- Is it an Early Predictor of Hypoxaemia in COVID-19 Patients? TC01-TC04
Dr. Ajay Sharawat, Postgraduate resident, Department of Radiodiagnosis, Kalinga Institute of Medical Sciences, KIIT University, Bhubaneshwar, Odisha, India.
Introduction: Novel Coronavirus-2019 (nCoV-2019) is capable of human-to-human transmission and can lead to acute respiratory distress syndrome similar to Middle East Respiratory Syndrome (MERS) due to lung parenchyma destruction. Some patients with COVID-19 consistently demonstrated no hypoxaemia, however, some patients develop sense of difficulty in breathing due to increased airway resistance.
Aim: To assess the potential of High Resolution Computed Tomography (HRCT) thorax as an early predictor of hypoxaemia in COVID-19 patients.
Materials and Methods: A prospective longitudinal cohort study of 1000 Reverse Transcription Polymerase Chain Reaction (RTPCR) confirmed COVID-19 and HRCT thorax positive patients, who were monitored simultaneously for SpO2 levels, were undertaken. HRCT findings were graded into Computerised Tomography Severity Index (CTSI) and correlated with patientâ€™s SpO2 levels, at the time of scan on admission. Patients, who had normal SpO2 levels (≥95%) at the time of initial scan, were monitored upto five days. Pearson's correlation test was used to find correlation between CTSI and SpO2 levels.
Results: In present study group there was male predominance (4:1). Fever was the most common clinical presentation followed by cough. HRCT thorax features were categorised as Typical 769 (76.9%), Indeterminate 176 (17.6%) and atypical 55 (5.5%). 371 (82.8%) patients with SpO2 >95% were having CTSI between 0-7, similarly 189 (54.4%) patients with SpO2 90-94% were having CTSI between 8-15 and 133 (64.8%) patients with SpO2 <90% were having CTSI between 16-25. So, the present study categorised the patients into three groupsCategory 1 (CTSI 0-7), Category 2 (CTSI 8-15) and Category 3 (CTSI 16-25) for better and prompt identification of clinical severity and their management. Majority of patients in CTSI category 1, 2 and 3 were having SpO2 levels ≥95%, 90-94% and <90%, respectively. Statistical correlation between CTSI and SpO2 levels at the time of initial scan was significant (Pearsonâ€™s correlation coefficient (r)=-0.261 and p-value <0.01). Number of patients who developed hypoxaemia (SpO2 <95%) on follow-up in CTSI Category 1, 2 and 3 were 42 (11.32%), 10 15.87%) and 2 (14.28%), respectively. The association between CTSI and development of hypoxaemia based on follow-up SpO2 levels was statistically found to be insignificant (chi-square value=1.21, degree of freedom (d.f.) 2 and p-value=0.570).
Conclusion: In present study group, a negative correlation was established between CTSI and SpO2 levels. The association between CTSI and development of hypoxaemia on follow-up SpO2 monitoring was found to be non-significant statistically. So, HRCT thorax cannot be relied upon as an early predictor of hypoxaemia in COVID-19 patients.