Evaluation of Cardiopulmonary Diseases by Ultrasound

Overview

Historically, ultrasound imaging of the lung parenchyma has been challenging because of the high total ultrasound energy attenuation and scattering by the air in the lungs. However, recent technological advancements have allowed for rapid assessment of various pulmonary diseases via the use of lung ultrasound. Furthermore, it has been shown that clear reproducible Doppler signals can be recorded from the lung parenchyma by means of a pulsed Doppler ultrasound system incorporating a special signal-processing package. The LDS may contain information of significant diagnostic and physiological value regarding the pulmonary parenchyma and vasculature, as well as the cardio-vascular system in general. In a pilot clinical validation study of patients with acute decompensated heart failure (ADHF) patients, LDS signals unique to ADHF patients were identified, that superpose on the normal Lung Doppler Signals (unpublished data). These are high velocity "disorganized" variable signals that are not synchronous with the cardiac cycle but rather sometimes with respiration.

Study Purpose and Rationale The purpose of this study is to assess the utility of noninvasive assessment of lung Doppler signals performed via transthoracic parametric Doppler. The study has two major objectives and is thus, divided into two phases, which are on a continuum. Phase 1: The objective is to further evaluate LDS among patients presenting to the emergency department with acute dyspnea, in order to determine the diagnostic value of this non-invasive method to distinguish cardiac from pulmonary causes of dyspnea. Phase 2: In addition, for those patients admitted to the hospital with a clinical diagnosis of ADHF, we would like to further characterize changes in daily lung Doppler signal as a surrogate biomarker of intravascular volume status, as assessed by clinical assessment. Study Design and Methods: 1\. Overall study design Phase 1: Prospective cohort study of patients presenting to the Massachusetts General Hospital emergency department with acute dyspnea. . In addition, at MGH, pts admitted to the cardiac floors (Ellison 9, 10, 11) and general medicine floors (White 9, 10, 11) with an admitting diagnosis of heart failure, who presented with acute dyspnea, will be approached for enrollment within 24 hours of hospital admission. All patients with acute dyspnea will undergo routine clinical assessment, laboratory testing, and diagnostic imaging. In addition, all patients will also undergo transthoracic parametric Doppler ultrasound based assessment of LDS. Patients will be treated as usual, under the direction of the attending physician. Two independent cardiologists will perform detailed chart review on all patients to determine the etiology of acute dyspnea. They will be blinded to the results of the LDS. In the event of discrepant findings, a third cardiologist will perform a final detailed chart review to adjudicate the diagnosis. Additionally, radiologist employed at MGH and who are independent to the study may perform blinded adjudication of the study participants' chest x-rays (CXR) obtained in the Emergency Department on the day of enrollment into the study Phase 2: In addition, patients diagnosed with ADHF (diagnosed based on the criteria described below), will undergo daily TPD and assessment of LDS to further characterize changes in LDS over time, until the day of discharge or up to day 7 of hospitalization, whichever comes first. In addition to the initial inpatient scans, study staff will try to acquire a final scan within 72 hours of discharge for patients diagnosed with ADHF, regardless of the day of hospitalization. This cohort of patients will also undergo daily clinical assessment of volume status, weight measurement, and BNP assessment. In the event that repeat BNP or NT-proBNP labs have not been drawn within 72 hours of discharge, study staff will coordinate with the pathology laboratory (Dr. Kent Lewandrowski) to perform the assay as a research test using excess clinical specimen from the subject's routine clinical blood draw if available. Research subjects will not be charged for the cost of the BNP or NT-Pro-BNP assay.