Introduction
Coronavirus disease 2019 (COVID-19) is a new respiratory disease that first appeared in Wuhan, China (1). The COVID-19 disease has killed more than 5 million people globally (2) and has affected the lives of millions of people around the world due to the quarantine of cities, business closures, and social distancing (3). COVID-19 is associated with many health problems. One of these important complications is severe acute respiratory syndrome (4). Since the outbreak of this contagious disease, the number of cases has increased rapidly and it has affected all age groups and people all over the world (5). COVID-19 patients hospitalized in the ICU often need mechanical ventilation and extracorporeal membrane oxygenation, which increases treatment costs (6). The financial crisis caused by this virus causes mental problems and suicide among people (7). The complications caused by this virus include pulmonary, cardiovascular, neuropsychiatric, hematologic, gastrointestinal, renal, endocrine, dermatologic, and musculoskeletal problems (8). However, the mechanism of the effects of factors causing long-term complications of COVID-19 is not yet clear.
There are several factors that affect COVID-19 incidence such as age, lung disease, hypertension, heart disease, kidney disease, or metabolic disorders. There are also other factors like physical distance, ventilation, face masks, socioeconomic factor, vaccination, SARS-CoV-2 variants, and the availability of COVID-19 testing that are helpful in this virus prediction (9). In critically ill patients with Covid-19, the body’s metabolism may experience severe disturbances. For example, the function of pancreatic beta cells is often affected and the regulation of blood glucose is disturbed (10). Poor nutrition of critically ill patients may be associated with increased length of stay in the intensive care unit (ICU) and higher mortality (11). Due to the persistent pro-inflammatory immune response, the risk of nutritional stress such as malnutrition is higher in patients with COVID-19.
Previous studies reported that enteral feeding does not necessarily improve the status of COVID-19 patients (12). The results of one meta-analysis study indicated that early enteral nutrition is associated with a lower risk of mortality and SOFA (Sequential Organ Failure Assessment) score compared with delayed enteral nutrition in critically ill COVID-19 patients but it did not significantly (p >0.05) reduce the length of hospital stay, length of ICU stay and days on mechanical ventilation compared to delayed enteral nutrition or parenteral nutrition, respectively (13). Another meta-analysis showed that mortality was reduced in the early enteral nutrition group compared with the delayed enteral group. It has also been indicated that enteral nutrition may be the preferred route to enhance the integrity of the gut and promote immune function (14). The present study aimed to investigate the association of enteral feeding with biochemical and pathological indices associated with survival/mortality in COVID-19 patients.