Estimation of blood lactate and bicarbonate levels after stored blood transfusion to predict ICU admission in patients undergoing major head and neck surgeries: A prospective observational study.

Background and aims: Major head neck surgeries are often associated with major blood loss requiring blood transfusion. However, in spite of transfusion, patients usually suffer adverse postoperative outcomes. Biomarkers can help in identifying such events early. This observational study was conducted to compare blood lactate and bicarbonate levels as predictors of adverse postoperative outcomes.

Materials and methods: Forty-eight adult American Society of Anesthesiologists Physical Status I-III patients met the inclusion criteria. Intraoperative blood loss was managed with stored blood transfusion as per transfusion trigger. Blood lactate and bicarbonate levels were measured preoperatively (Tbas), at the immediate postoperative period (T0), and at 8 h (T8), 16 h (T16), and 24 h (T24) postoperatively. Outcomes such as need for intensive care unit (ICU) admission, length of ICU stay, intraoperative blood transfusion, re-exploration rate, and mortality were recorded.

Results: Blood transfusions and ICU admissions were required in 19 (39.6%) and 24 (50%) patients, respectively. Lactate levels of patients requiring blood transfusion and admission to ICU rose significantly from their baseline (1.30 ± 0.41 mmol/l) to 2.80 ± 1.14 mmol/l at the immediate postoperative period, which fell to 2.06 ± 0.78 mmol/l at 24 h postoperatively, compared to other patients who did not require transfusion and ICU admission (P < 0.001). The bicarbonate value did not show any significant change from its baseline (22.68 ± 1.83 mEq/l) at all time points (P = 0.8). In addition, no significant difference was noted regarding ICU admissions (P = 0.659) or blood transfusions (P = 0.788).

Conclusions: Following major head and neck surgeries, blood lactate level is a good predictor, but bicarbonate is a poor predictor of the need for blood transfusions and ICU admission. Intraoperative blood transfusion failed to prevent rise in blood lactate level, which is taken as a surrogate marker of tissue hypoxia.