Lung ultrasound predicts left-sided filling pressures in patients with cardiogenic shock admitted to the cardiac intensive care unit

Abstract

Abstract Background Left and right filling pressures, as well as cardiac output, are key targets in optimising treatment of cardiogenic shock (CS). Invasive pulmonary artery catheters can provide these data but are associated with complications and are not available in all hospital settings. Lung ultrasound (LUS) can detect pulmonary congestion in patients with heart failure (HF) and may be an alternative to invasive monitoring. We assessed the correlation between LUS score and invasive haemodynamic parameters in patients with CS admitted to the cardiac intensive care unit (CICU) of a North American cardiac centre. Methods We prospectively evaluated consecutive patients who underwent pulmonary artery catheter insertion in the CICU. Haemodynamic parameters including right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP) were measured and cardiac output (CO) was calculated using the thermodilution method. This was immediately followed by an 8-zones LUS done by a critical care cardiologist who was blinded to the invasive hemodynamic measurements. The LUS score was calculated by counting the total number of B-lines in all 8 zones, with a higher score indicating greater congestion. Correlations between LUS score and hemodynamic parameters were evaluated using Pearson's correlation. Results Ninety-six measurements from 60 patients were included, aged 58±14 years with 27% female. The most common diagnosis at admission was cardiogenic shock, followed by acute myocardial infarction and HF exacerbation. Most patients were at SCAI stages C and D at the time of assessment. The mean number of B-lines at LUS was 10.1±8.2. Mean RAP was 8.5±4.6 mmHg, PCWP 16.2±6.3 mmHg and CO of 5.0±1.8 L/min. The total number of B-lines was correlated with PCWP (r=0.66, P<0.001, see Figure 1), RAP (r=0.26, P<0.001) and cardiac output (r=−0.23, p=0.02). Due to the correlation of B-lines in LUS with PCWP, we then evaluated the area under the ROC of the LUS to identify patients with PCWP ≥15 mmHg. The number of positive zones (≥3 B-lines) showed an AUC of 0.81 (0.72–0.89), P<0.001. In 36 patients, we had repeated measurement with more than 12 hours apart. The delta change in PCWP was correlated with delta change in the number of B-lines (r=0.59, P<0.001). Conclusion Elevated LUS score in patients with CS is associated with worse invasively-measured LV filling pressures, but less so with RAP or CO. LUS can serve as a useful adjunct to the clinical assessment of patients with CS who do not receive invasive hemodynamic monitoring, either at a single timepoint or to detect changes in clinical status over time, to guide ongoing management. Funding Acknowledgement Type of funding sources: None.