It is important for nursing and medical technology students to understand the function and diseases of the heart. Recognized as the most critical organ in the body, the heart feeds all others. Adequate blood flow is essential for this process to occur properly, and for a variety of reasons, that flow can vary. A hemodynamic assessment measures the complex forces involved in this variance in blood flow.
The assessment is useful in diagnosing and measuring the extent of diseases, such as hypertension and congestive heart failure. This is important since, according to the Centers for Disease Control, heart failure afflicts over five million Americans. In fact, for every nine deaths in the U.S., one is attributable to heart failure.
Congestive Heart Failure (CHF)
Whether from weakness of the heart muscle or some defect, the heart sometimes does not pump enough blood to critical organs, especially the kidneys. Weakened kidneys then become unable to remove fluid from the body adequately. Some of the signs of congestive heart failure include a buildup of fluid in places like the legs, the liver and the lungs. Only a thorough hemodynamic assessment can properly predict the congestive heart failure prognosis for any particular individual.
The circulatory system consists of two components. The heart's right side is involved in low pressure, pulmonary circulation, where there is little resistance in flow; the heart's left side is involved in systemic circulation, which flows under high pressure and with increased resistance. CHF results primarily from problematic systemic hemodynamics, and especially involves the left side of the heart. However, hemodynamic measurements are not limited only to the function of the heart's left side. Instead, the health of the entire heart muscle is measured.
Hemodynamic Assessment Tools
Whether measured invasively or non-invasively, hemodynamic data guides health care providers toward the correct congestive heart failure treatment for any given patient. Doppler echocardiography is the primary tool for noninvasive measurement. Available for quick use, it both visually and graphically measures restrictions of the heart's outflow, myocardial thickness, the heart chamber size and valvular function.
A host of invasive assessment methods includes lithium dilution cardiac output in which the flow of injected lithium is measured. Measuring pulse contour cardiac output involves the insertion of both an artery and central venous catheter and then using various measurements. A pulmonary artery catheter has been commonly used for decades and is critical for emergent assessments and interventions.