This study aims to determine the relationship between the severity of lung tomographic compromise with arterial oxygenation and inflammatory markers in patients with COVID-19, and to evaluate the relationship between the CTSS tomographic severity score and the mortality risk in a high-altitude population. A retrospective, longitudinal study reviewed medical records between January and July of 2021 at the Daniel Alcides Carrión Regional Teaching Clinical Surgical Hospital in Huancayo. Categorical variables were analyzed with the chi-square test, continuous variables with the ANOVA test, and correlations between continuous variables were calculated by calculating Spearman's coefficient. The predictive capacity of the CTSS score was evaluated by determining the ROC curve. Two hundred-three medical records were reviewed; 65% of patients (n = 132) were male and 84.7% came from Huancayo (n = 172). The average age was 55.86 years. 58.6% of the CT scans were in the peak phase and 14.3% in the progressive phase. The average value of the PaO2/FiO2 ratio in deceased patients was 107.4; in survivors it was 196.10. Mortality was 12% in those with mild lesions, 28.8% in those with moderate involvement, and 79.2% in those with severe pulmonary lesions. PO2/FiO2, SatO2/FiO2, DHL, CRP, D-dimer, and lymphopenia correlated with the severity of pulmonary tomographic patterns. Tomographic lesions and inflammatory marker values were more severe than in most international studies.