CONCLUSION
The European Society for Clinical Nutrition and Metabolism defined
malnutrition as a condition resulting from a lack of nutrition or intake
that leads to changes in body composition (reduction of lean mass) and
body cell mass, resulting in reduced physical and mental function and
impaired clinical outcomes from the disease. Additionally, cardiac
cachexia triggers impaired neuroendocrine and immunological function,
and it is considered an indicator of poor prognosis regardless of age
and disease severity16,17.
Malnutrition is generally associated with humoral and cellular immune
dysfunction, inflammatory response change, and the wound healing process
delay or failure. It is well known that malnutrition is closely related
to the incidence of postoperative complications, length of hospital
stay, quality of life, and increased mortality of malignant
tumors18. Besides, the negative impact of long-term
calorie and protein deficiencies on critically ill surgical patients’
outcomes has recently been demonstrated19. The
decreased response of albumin and lymphocytes to acute disease indicates
low immunonutritional status. The PNI was calculated based on the serum
albumin concentration and lymphocyte count of peripheral blood.
Therefore, the PNI score should be considered a clinical element and
indicator of disease severity in patients undergoing cardiac surgery.
Some studies recently reported that a lower PNI level was significantly
associated with higher mortality in patients with cardiovascular
diseases20-23. One of the most beneficial aspects of
PNI is not time-consuming, and no special equipment is required.
Therefore, it can be easily integrated into routine clinical practice.
Although the prognostic significance of the PNI has been reported
previously in several types of abdominal or gastrointestinal surgery,
its relevance in cardiovascular surgery has not been proven. The
surgery’s success depends not only on technical surgical skills but also
on the preoperative nutritional status.
Keskin et al.24 showed a significant relationship
between PNI level and mortality (in-hospital and long-term) in coronary
artery disease patients undergoing CABG. In addition, Hyashi et
al.25 retrospective study showed that a high PNI value
was found to decrease mechanical ventilation duration, ICU stays, and
infection rates. In the multivariate analysis, in addition to age and
female gender, a low PNI value was determined as an independent
predictor for mortality. Recent published Lee et al.26study is the first to assess the usefulness of the PNI in adult cardiac
surgery using only CPB and showed that a lower PNI was an independent
predictor of early morbidity and mortality, and was also related to
prolonged mechanical ventilation support and ICU stays.
In cardiac surgery, an increasing number of older people are accepted
for elective surgery. When low preoperative PNI is detected in elderly
patients, postoperative nutritional management such as serum albumin
supplementation, dietary maintenance, or nutritional supplementation
should be considered to improve patients’ nutritional
status27.
Our research demonstrated that the PNI value was statistically low in
the mortality group. There was significantly different a higher tendency
for postoperative hospital-acquired infection and stroke in the
mortality group. PNI may be used to predict patients’ outcomes before
cardiac surgery and select an adequate surgical strategy. In that case,
it must be useful for choosing the biological or mechanical materials
for valvular surgery and determining graft materials in coronary
surgery. In the case of patients with a low PNI, less invasive surgery
may be suitable if possible.
Our study does not include the effects of preoperative nutritional
support on postoperative mortality and morbidity in patients with low
PNI values. Further studies are needed to show the results of
preoperative nutritional support in elective cases.
Preoperative low PNI level was evaluated as an independent predictor of
long-term cardiovascular outcomes. Also, it was statistically
significantly associated with postoperative mortality and morbidity in
cardiac surgery. According to the results we obtained in our study, we
firmly believe that PNI is a useful and suitable parameter for
preoperative assessment of nutritional status and should be regarded in
managing the indication and strategy in on-pump cardiac surgery.
Authors’ contributions The authors’ responsibilities were as
follows: AG, OAO and SAS conceived the study and designed the search
strategy; AG and OAO conducted the study selection; SAS and NK conducted
data extraction; AG, NK and DD evaluated the risk of bias of included
studies; AG, OAO and SAS conducted the data analysis and interpretation
of results; AG, OAO and IBS wrote the first draft of the manuscript; AG
and OAO revised the manuscript; all authors read and approved the final
version of the manuscript.