A NON-INVASIVE SYSTEM FOR HOME MONITORING OF FLUID STATUS IN PATIENTS WITH HEART FAILURE

A non-invasive system to accurately and consistently monitor patients with congestive heart failure (CHF) has been designed, developed, and undergone preliminary testing. The system measures both bioimpedance and heart rate of a CHF patient after a hospital discharge. It consists of an electrodeembedded floor mat and a mountable visual display. The mat form factor is intended to integrate into a patient’s home and promote user compliance by incorporating the measurements into the patient’s daily routine. The low profile mat can be placed in front of a bathroom sink or by the bedside. Data from the mat is wirelessly transmitted both to a visual display for immediate user feedback and to a website for remote monitoring by a physician. This device will enable clinicians to monitor bioimpedance and heart rate over time and intervene as needed before an emergency re-hospitalization is required. INTRODUCTION Congestive heart failure is of great detriment not only to the quality of life of those afflicted [1], but also to the healthcare system as a whole [2]. The incidence of CHF has risen in the United States, in part, due to an aging population and improvements in the treatment of acute events such as myocardial infarctions [3]. An estimated five million people are presently diagnosed with CHF in the United States with over 400,000 new diagnoses annually [4]. Every year, over one million patients are hospitalized for CHF, costing the US healthcare system close to $29 billion [2]. Although there are numerous etiologies of heart failure (coronary heart disease, valvular disease, infectious and inflammatory conditions, metabolic derangements), monitoring of the clinical symptoms is similar across the majority of patients. Hospital readmissions are common in patients with CHF. According to a recent study, almost one in two patients will be readmitted to the hospital within four to six months of discharge [5]. It has been estimated that up to 50% of early readmissions due to CHF-related ailments may be prevented if symptoms are recognized early enough for preventative care to be administered [6]. Proactive and routine monitoring of patients in their home environment allows for early diagnosis and preemptive treatment of a decompensation event, which can prevent hospitalizations or minimize the length of stay in the hospital if readmission is unavoidable. The decreased number of hospital days also acts to alleviate economic burdens on the healthcare system. Figure 1. Frequent re-hospitalizations occur after the diagnosis of heart failure. Many of the clinical symptoms (shortness of breath, fatigue, difficulty in exercise) that force patients to seek clinical help are either too indeterminate or present so late that re-hospitalization is required. [7] CLINICAL BACKGROUND Congestive heart failure is characterized by fluid overload. It is a result of complex physiological mechanisms that are activated in patients with cardiomyopathy. Ischemic cardiomyopathy, secondary to coronary heart disease, frequently leads to left ventricular systolic dysfunction and accounts for 50% of cases of CHF. Ventricular systolic dysfunction, also known as systolic heart failure, can result in a drop in cardiac output, a direct consequence of which is insufficient oxygen and nutrient delivery to major organs in the body, including brain and kidneys. One major compensatory homeostatic mechanism employed by the body to maintain adequate perfusion to critical organs is retention of salt and water by the kidneys, thus increasing total body water content. Increasing intravascular fluid attempts to maintain