Comparative Assessment of Phase Angle, Lean Body Mass Index and Tissue Edema to Assess the Nutritional Status and Immediate Outcome of Cardiac Surgery Patients:an Open, Prospective Study of Observation / Recording

In general, malnutrition in surgical patients is associated with a higher risk of postoperative infections, decreased immune response, more cardiac complications, prolonged mechanical ventilation , and a higher rate of reimportation due to several other complications than lead to an increase in morbidity and mortality, a prolongation of the total hospitalization time in the ICU[intensive care unit ] and the chamber, and a delay in the healing of the surgical trauma .

The presence of a low percentage of lean mass, as calculated by the technique of bioelectric conductivity, practically means a small percentage of muscle tissue. However, muscle tissue is an important, if not the only source of amino acids for both protein synthesis and gluconeogenesis in stress conditions, such as surgery and the first postoperative days. Thus, post-operative patients in general, and cardio-operated patients, in particular, having a low lean mass have minimal reserves to the stress requirements, resulting in an increased risk of complications.

In the last few years, the most reliable indicator of malnutrition- in addition to the lean mass index - began to be considered the phase angle, which is also calculated when measuring the bioreduction of electrical conductivity, although there is a very recent challenge . The phase angle expresses the relationship between the electrical reactance, i.e. the state of the cell membrane, to resist the permeability and the resistance, i.e. the restriction to the flow of the electrical current through the body, mainly related to the water of the tissues . Like the FFM[fat-free mass]- index, the phase angle uses the total water of the tissues, and thus also reflects the cell mass. In addition, however, it also measures the resistance of cell membranes, so it also evaluates their quality and is therefore considered to be a reliable indicator of poor nutritional status , although some also maintain demur due to the possible poor distribution of extracellular fluid in cardiological patients.

From all of the above, it appears that there are some gaps in the evaluation of the patients who are going to undergo cardiac surgery regarding their nutritional status, both because the classic nutrition control indicators are not fully documented as being reliable for these patients, and there are no studies to monitor and compare body composition directly to any other index postoperatively.