B-type Natriuretic Peptide (BNP) as a Surrogate Marker Guiding Post-operative Fluid Off-loading

Creighton University Medical Center is 334-bed Level I Trauma Center that hosts a wide variety of surgical and trauma patients. Many of these patients, including and especially those with pre-existing cardiac morbidities, develop symptoms of congestive heart failure (CHF) following trauma or surgical intervention because of a combination of physiological factors including third spacing followed by self-diuresis, and decreased contractility post injury. Normally, following the onset of CHF, surgeons begin treatment based on their clinical judgment of hemodynamic parameters and radiographic findings. CHF is known to increase morbidity, mortality, hospital length of stay and overall expenditure to the health care system and preventative measures and directed treatment modalities have potential to improve patient care and healthcare economics.

BNP, also known as beta-natriuretic protein or CHF peptide, is a cardiac neuro-hormone synthesized by the cardiac myocytes. It is released as a preproBNP peptide of 134 amino acids and is cleaved into proBNP (108 amino acids) and a signal peptide of 26 amino acids. ProBNP is subsequently cleaved into BNP (32 amino acids) and the inactive N-terminal proBNP peptide (NBNP; 76 amino acids). The effects of BNP are vasodilation, natriuresis and diuresis1.

Left ventricular end-diastolic wall stress (EDWS) measurement and ejection fraction are well established surrogates to predict the onset of CHF but require the invasive procedure of cardiac catheterization.

The mainstay of the treatment of CHF is diuretic drugs to try to remove excess fluid from the patient. In this project we plan to identify patients at risk for CHF and divide them into two groups. In one group BNP will be used to guide diuretic dosage and in the other conventional clinical parameters will be used.