Assessment of Lung Parenchyma Recovery after Antibiotic Administration using Lung Ultrasound in Critically Ill Patients with Pneumonia

Abstract

Background: Pneumonia is a common cause of Intensive care unit (ICU) admission, requiring frequent imaging for following up parenchymal lung involvement and antibiotic response. Being bedside and non-invasive technique; lung ultrasound (US) is increasingly used in ICU. Objectives: Assessing accuracy of lung ultrasound in detecting parenchymal lung recovery following antibiotic administration in critically ill patients with pneumonia. Methods: Fifty patients with pneumonia were included in the study with time-dependent analysis for APACHEII, CURB-65 and modified CPIS. Lung US at day 0 described basal lung condition then according to changes in lung parenchyma, US score could be first calculated at day 3. At day 5 US score was calculated again and changes in score (delta score) was calculated to asses ability of US to predict early good antibiotic response and finally lung US was repeated at day 7, score calculated to detect lung parenchyma recovery and compared with follow up CT for accuracy and agreement. Air bronchogram was reported whenever seen, described as static or dynamic and assessed in follow up examinations to be compared with CT follow up. Results: Lung US score ranged from -2 to 17 with mean value of 8.75 ± 3.88 for improving patients, while worsening patients showed lung US score of -11 to -20 with mean value of -10.08 ± 6.95 with high statistical significance (p<0.001).The best cutoff value of lung US score changes for detecting good response to antibiotic was 2.5, detected using area under the curve (AUC) (p<0.001). Ultrasound score on day seven showed excellent sensitivity and specificity of 91.89% and 92.31% respectively when compared to CT with PPV of 97.14% and NPV 80% and accuracy 92% with strong statistical significance (p<0.001). Air bronchogram showed sensitivity of 61.5% and specificity of 89.1% and with PPV of 66.67% and NPV of 86.84% and accuracy of 82% and moderate agreement (0.52) with CT while B-lines were significant for assessing lung reaeration with sensitivity of 69.2% and specificity of 67.5% and accuracy of 68% but with fair (0.31) agreement with CT (p<0.027) in detecting parenchymal lung recovery. Conclusion: Lung US is a reasonable bedside method for quantifying parenchymal lung recovery in patients with pneumonia who are successfully treated with antibiotics.