Article: Comparative Performance of Pulmonary Ultrasound, Chest Radiograph, and CT Among Patients With Acute Respiratory Failure*

Tierney DM, et al. Crit Care Med. 2020 Feb;48(2):151-157. doi: 10.1097/CCM.0000000000004124. PMID: 31939782.

Overview: The study aimed to evaluate how well Pulmonary Ultrasound and CXR were able to localize lung pathology, and lead to the right diagnosis compared to the gold standard of chest imaging, Chest CT.

Study Setting: MICU, SICU, and Neurologic ICUs at a 670 bed urban teaching hospital.

Study Sample: 67 patients with Acute Respiratory Failure (ARF) requiring mechanical ventilation who had had CXR and chest CT performed within 24 hours of intubation.

Intervention: 9-point pulmonary ultrasound protocol at the time of intubation compared to portable CXR and Chest CT

Results: The study found that overall agreement of pulmonary US and portable CXR findings with correlating lobe on CT was 87% vs. 62%; p < 0.001 respectively.

Relaxing the agreement definition to a matching CT finding being present anywhere within the correct lung (“lung-specific” agreement), not necessarily the specific mapped lobe, showed improved agreement for both pulmonary ultrasound and portable chest radiograph respectively (right lung: 92.5% vs 65.7%; p < 0.001 and left lung: 83.6% vs 71.6%; p = 0.097).

The highest lobe-specific agreement was for the finding of atelectasis/consolidation for both pulmonary ultrasound and portable chest radiograph (96% and 73%, respectively).

The lowest lobe-specific agreement for pulmonary ultrasound was normal lung (79%) and interstitial process for portable chest radiograph (29%).

Lobe-specific agreement differed most between pulmonary ultrasound and portable chest radiograph for interstitial findings (86% vs 29%, respectively).

Pulmonary ultrasound had the lowest agreement with CT for findings in the left lower lobe (82.1%).

Pleural effusion agreement also differed between pulmonary ultrasound and portable chest radiograph (right: 99% vs 87%; p = 0.009 and left: 99% vs 85%; p = 0.004).

Pulmonary ultrasound findings correlated with CT findings much better compared to how well CXR findings correlated with CT findings across all variables they measured.

Conclusions:

A 9-point pulmonary ultrasound protocol strongly agreed with specific CT findings when analyzed by both lung, and lobe specific location among a diverse population of mechanically ventilated patients with ARF; and that pulmonary ultrasound significantly outperformed portable CXR.