Correlation of Inferior Vena Cava Diameter via Point-of-Care Ultrasound and N-terminal pro-B-type Natriuretic Peptide Level in Heart Failure

Background: Heart Failure (HF) affects 6.2 million people annually. Despite improved survival, one in five HF patients is readmitted within 30 days. Pulmonary congestion is a risk factor for readmission and can manifest weeks before symptoms occur. Point-of-care ultrasound (POCUS) is a portable tool that enables immediate visualization of the inferior vena cava (IVC) and lungs. Purpose: To examine the correlation between IVC diameter via POCUS and N-terminal pro-B-type natriuretic peptide (proBNP) level in HF patients seen in a post-discharge clinic. The secondary aim was to assess for the presence of pleural effusions with POCUS. The tertiary objective was to establish correlation between IVC non-collapsibility and volume overload. Methods: A convenience sample of adults with HF were seen in a nurse practitioner (NP)-led post-discharge clinic within 12 days of hospitalization. The setting was a large tertiary care hospital. Inclusion criteria were patients with Medicare and HF diagnosis, recently hospitalized. Medical records were reviewed for relevant patient outcomes. The NP measured IVC diameter, determined IVC collapsibility, and examined pleural cavities to assess for effusion. A proBNP level was drawn during the visit. Data were analyzed descriptively and using Spearman correlation. Results: The sample included 21 patients with mean age of 78.1; 52.4% female, and 42.9% Caucasian. The population had extensive co-morbidities: 85.7% with hypertension, 23.8% diabetes, 61.9% chronic kidney disease. Heart failure with preserved left ventricular function comprised 66.7% of the sample. Median proBNP level was 4095 pg/mL. Normal value for proBNP levels is less than 125 pg/mL for patients under 75 years old, and less than 450 pg/mL for people over age 75. Mean estimated glomerular filtration rate (GFR) was 46mL/min. The normal range for GFR is 90-120 mL/min. There was no correlation between IVC diameter and proBNP, r = 0.034, p=0.884). Pleural effusions were identified