Background: Pulmonary B-lines are a highly sensitive sonographic sign of pulmonary edema in patients with Acute Decompensated Heart Failure (ADHF) (3). When found prior to discharge, this finding has been shown to accurately predict re-admission and mortality on short term follow up (4,5,6). Inferior vena cava (IVC) diameter and collapsibility can be used as a surrogate of right atrial pressure (7), and pre-discharge assessment large IVC size and reduced IVC collapsibility have also been shown to predict re-hospitalization for acute decompensated heart failure(8,9,10). We hypothesized that pre-discharge B-line counts and abnormal IVC parameters would predict composite 30 and 90 day rates of admission and death. This was a pilot project to determine if we should move forward with a quality improvement project to institute pre-discharge lung ultrasound on all ADHF patients. The study was approved by the Institutional Review Board at the Bruce W Carter Miami VA Hospital.
Methods: Patients admitted with a primary diagnosis of acute decompensate heart failure underwent lung and IVC ultrasound prior to discharge. Patients underwent a supine scanning of 7 lung zones (4 on right, 3 on left (cardiac area excluded)) for presence and number of B-lines (Figure 1). They also underwent measurement of IVC size and collapsibility with inspiratory sniff. IVC dilation was defined as >2.1 cm and lack of collapsibility was defined as < 50% collapse, as defined by the American Society of Echocardiography (11). Patients were followed at 30 and 90 days for a composite primary outcome of readmission or death via telephone and chart follow up. Statistical analysis was conducted with t-tests for continuous variables and fisher’s exact test for dichotomous variables.
Results: A total of 37 patients were enrolled in the study. The overall rate of the composite outcome was 18.9% (7 patients) and 29.7% (11 patients) at 30 and 90 days respectively. There were 2 deaths at 90 day follow up.In those patients with more than 4 total B lines, there was a trend towards significantly higher rate of readmission or death at 90 days but not at 30 days (30 days: 27.7% vs 11.1% (p= NS); 90 days: 44.4% vs 15.8%, (p=0.07 )) (Figure 2) There was also a trend toward significantly higher B-line count in those who suffered readmission or death at 90 days but not at 30 days ( 30 days: 7.1 vs 6.1 B-lines (NS) , 90 days: 8.9 vs 5.2 B-lines (p=.09)). Amongst those patients with systolic heart failure (n=21) there was significantly higher B-line count in those who were readmitted or died at 90 days than those who were not ( 9.9 vs 4.2 B lines (p=< 0.05)). There was a higher rate of patients who had dilated and non collapsible IVCs amongst those who experienced readmission or death at 90 days (7/10 patients, 70%) than amongst those who were not (7/21 patients, 33%), however this was not statistically significant (p=NS)
Conclusions: There are trends toward higher pre-discharge B-line counts in those patients who experience readmission or death at 90 days amongst an urban, veteran population. IVC parameters did not appear to predict readmission or death although the study likely is underpowered to detect differences. The data was encouraging enough for local hospitalist leaders to go ahead with a larger project to incorporate pre-discharge lung ultrasound in all heart failure patients. The hospitalist group has begun a comprehensive training program in lung ultrasound for heart failure to use another piece of data to use in heart failure assessment.