Evaluating the effect of preoperative anemia on intraoperative transfusion, postoperative morbidity, and mortality in major abdominal surgery

Objective: Preoperative anemia has been associated with poor postoperative outcomes in cardiac surgery with many studies. The impact of preoperative anemia on outcomes in non-cardiac surgery patients is still controversial. In our study, we aimed to investigate the frequency of preoperative anemia in major abdominal surgery, its effect on intraoperative blood transfusion, and its relationship with postoperative morbidity and mortality. Method: Data from patients over the age of 18 who underwent major abdominal surgery between January 2022 and June 2023 at the Akdeniz University Faculty of Medicine Hospital were analyzed in our study. Emergency operations and patients with bleeding disorders were excluded from the study. Demographic data (age, gender, height, weight, ASA classification) and comorbid diseases (HT, DM, COPD/Asthma, PVD, CHF, CKD, CAD) of the patients, anticoagulant or antiaggregant use history were recorded from the hospital database and anesthesia assessment forms. Preoperative and postoperative laboratory values, intraoperative transfusion amounts, postoperative hospital and intensive care unit stay lengths, and postoperative morbidity and mortality presence were recorded from the hospital database. Postoperative morbidity was investigated under 10 headings: sudden cardiac arrest, myocardial infarction, pneumonia, need for mechanical ventilation, cerebrovascular event, acute kidney injury, need for dialysis, surgical site infection, sepsis, venous thromboembolism, and need for re-operation. The duration for postoperative morbidity and mortality was determined as the period until the patients were discharged from the hospital. The data obtained in the study were analyzed using various statistical methods using the SAS 9.4 program. Findings: Data from 341 patients were analyzed in our study. Patients were divided into two groups according to the World Health Organization's hemoglobin level classification criteria for anemia: those with preoperative anemia and those with normal hemoglobin levels.The analysis of the data of 341 patients showed that the prevalence of preoperative anemia was 56.6%. Intraoperatively, 139 patients received at least 1 unit of red blood cell suspension and 99 patients received at least 1 unit of FFP transfusion. The patients who received transfusions were analyzed after being grouped according to the presence of preoperative anemia. Preoperative anemia was present in 110 patients (79.1%) who received RBC transfusion, and 29 patients (20.8%) had normal hemoglobin levels. After statistical analysis, it was found that the need for transfusion was significantly increased in the presence of preoperative anemia. The effect of preoperative anemia on postoperative morbidity and mortality was investigated. In the 341 patients we studied, it was recorded that 1 had sudden cardiac arrest, 70 had pneumonia, 25 needed mechanical ventilation, 6 had cerebrovascular events, 31 had acute kidney injury, 9 needed dialysis, 23 had venous thromboembolism, 27 had sepsis, 42 had surgical site infections, and 31 needed reoperation. No patients included in the study had postoperative myocardial infarction. Mortality was recorded in 22 patients in the postoperative period. After statistical analysis of the postoperative data, it was shown that the presence of preoperative anemia significantly increased the risk of postoperative morbidity and mortality. Patients were analyzed according to the presence of preoperative anemia for their length of hospital stay and length of intensive care unit stay. The results of the analyzes showed that the presence of preoperative anemia significantly increased the length of hospital stay and intensive care unit stay. The effect of intraoperative blood and blood product transfusions on postoperative morbidity and mortality was also investigated in our study. Intraoperative RBC, FFP, and platelet suspension transfusions were analyzed separately. Statistical analyzes showed that intraoperative RBC transfusion significantly increased the risk of postoperative pneumonia, need for mechanical ventilation, AKI, need for dialysis, venous thromboembolism, sepsis, surgical site infection, and need for reoperation. Mortality was also significantly higher in patients who received intraoperative transfusions. Conclusion: In our study, we found that the presence of preoperative anemia in major abdominal surgery increases the need for intraoperative blood and blood product transfusions. We also showed that the risk of morbidity and mortality is increased in the presence of preoperative anemia. As a secondary outcome, we found that intraoperative blood and blood product transfusions also increase the risk of postoperative morbidity and mortality. The data we analyzed in our study covered the period up to hospital discharge in the postoperative period. A limitation of our study is that it did not examine complications that developed in patients after discharge.