Written by Chris Thom
Spoon Feed
More severe lung POCUS (L-POCUS) findings were associated with a higher risk of developing hypoxia, though this association was not strong across any scoring threshold.
If you’re not hypoxic now, can POCUS predict the future?
This was a case-control study of adult COVID patients in three emergency departments between 2021 and 2022. Patients with pulse oximetry > 92% on room air were eligible for enrollment. 10 onsite investigators obtained 7 L-POCUS views per hemithorax. Each location was scored on a 0 to 6 scale of severity. An additional outcome was a blinded review of the L-POCUS images by a separate remote investigator. Patients were then followed for the development of any hypoxia within the next 40 days, via both phone call and chart review.
148 patients were enrolled and successfully followed for the 40 day period. A hypoxic event occurred in 47 (32%) of patients. Median time to hypoxic event was 3.0 days (IQR 0-13.5). Overall L-POCUS scores were higher for patients who developed hypoxia (median 18, IQR 7-29.5) than for those who did not (median 8, IQR 4-15). Logistic regression analysis showed a significant association between L-POCUS scores and hypoxia (OR 1.05, 95%CI 1.02-1.08). However, the optimal cut-off L-POCUS score provided a sensitivity of 60% (95%CI 44-74) and specificity of 73% (95%CI 64-82) for predicting subsequent hypoxia.
How will this change my practice?
During the height of the COVID pandemic, we were all searching for strategies to appropriately allocate resources and determine who was at risk for worsening disease if sent home. L-POCUS holds significant promise as an easily deployed bedside tool that can aid in the detection and severity assessment of COVID. However, in the current study, the test characteristics were less favorable when compared to prior research on the more severely ill cohort. This is not to say that L-POCUS does not hold value for this population, but it should be used as an additional data point along with clinical gestalt and other variables.
POCUS pro-tips and clips:
COVID and viral pneumonias can be quite interesting on L-POCUS. Imaging acquisition should occur using the phased array or curvilinear transducer. While prior work has established specific lung zones to be evaluated, one can cover the anterior and posterior hemithorax via a few views on each hemithorax. COVID will appear as B-lines, which can become confluent in more severe disease. Interestingly, pleural thickening and irregularity can be seen, which aids in differentiation of COVID from interstitial fluid secondary to heart failure. Subpleural consolidations can also be identified (see below).
Source
Sensitivity of Lung Point-of-Care Ultrasound (POCUS) to Predict Oxygen Requirements in Emerging Viral Infections. J Ultrasound Med. 2025 Jan 21. doi: 10.1002/jum.16647. Epub ahead of print. PMID: 39835699
