The threshold for red blood cell (RBC) transfusion in the perioperative head and neck surgery setting is controversial. Some evidence favors liberal transfusion thresholds in head and neck procedures. Many head and neck oncology patients have multiple comorbidities, including anemia of chronic disease, malnutrition, and cachexia. Thus, liberal transfusion thresholds have been supported due to concern for patient frailty, oxygen delivery, and, in cases of free flap reconstruction, flap perfusion. However, other studies have favored more restrictive transfusion guidelines. This has been based on the thought that more restrictive transfusion thresholds are associated with lower rates of complications and long-term oncologic risk. The objective of this summary is to review existing literature and discuss indications for perioperative RBC transfusion in adult patients undergoing otolaryngology head and neck surgery. Transfusion thresholds in the perioperative head and neck surgery setting are evolving. The 2023 Association for Advancement of Blood and Biotherapies (AABB) guidelines recommend a restrictive transfusion threshold of < 7 g/dL in most perioperative settings. However, in patients undergoing major surgery or with a history of cardiovascular disease, clinicians may choose a threshold of < 7.5 or < 8 g/dL, although the restrictive transfusion threshold of < 7 g/dL is recommended in patients with hematologic or oncologic disorders. This recommendation is based on 45 randomized controlled trials with 20,599 participants 1. The AABB guidelines offer high-level evidence favoring restrictive transfusion thresholds, with a personalized approach based on patient risk factors such as preexisting medical conditions and elevated hypoxia risk factors. In head and neck oncologic patients, transfusion has been associated with survival disadvantages, resulting in clinicians favoring more restrictive perioperative thresholds. A dose-dependent association between transfusion volume and recurrence and mortality has been shown. A retrospective analysis of 683 patients showed that perioperative transfusion during surgery or within 7 days was associated with increased risk of recurrence (adjusted HR = 1.37, 95% confidence interval CI 1.1–1.7; p = 0.006) and decreased overall survival (adjusted HR: 1.37, 95% CI: 1.07–1.74, p = 0.011) in weighted Cox regression analysis. Furthermore, there was an association with cancer recurrence and overall survival in a dose-dependent manner, with a nonlinear relationship for recurrence and linear for overall survival. The risk of blood transfusion and cancer recurrence showed a concave relationship that increased and peaked at around 6 units and decreased gradually thereafter. The authors postulated that this association may be related to the immunomodulatory effects of RBC transfusion in promoting recurrence 2. In free flap patients, Enhanced Recovery After Surgery (ERAS) consensus similarly supports a restrictive transfusion strategy of < 7 g/dL. RBC transfusion has not been shown to consistently impact free flap survival, but it is associated with increased perioperative complications. Significantly higher rates of wound infection and death have been shown in a retrospective study. A higher threshold is indicated for those with cardiac disease or ongoing ischemia, as supported by the AABB guidelines 3. The relationship between transfusion and outcomes is poorly understood. Dumbill et al. demonstrated in human kidneys that impaired oxygen unloading from stored RBCs results in diffusion-limited oxygen release at tissues. In kidneys perfused with stored blood, renal respiration correlated inversely with the time-constant of oxygen unloading from RBCs. When the same kidneys were alternated between stored and rejuvenated RBCs, the rejuvenated cells improved oxygen diffusion capacity and increased cortical oxygen partial pressure by 60%, demonstrating that oxygen delivery becomes diffusion-limited during perfusion with stored blood. Although the oxygen-carrying capacity of blood is increased with transfusion, stored blood may compromise overall oxygen delivery to tissues by causing transport to become diffusion-limited 4. While most literature supports a restrictive transfusion threshold, one new study has revisited these guidelines. In a retrospective analysis of 590 patients, on univariate analysis, overall survival between transfusion and control groups did not differ significantly (p = 0.25). After adjusting for parameters with limited matching accuracy in cox regression analysis, a transfusion related hazard ratio was noted to be close to 1 (HR 0.92; 95% CI 0.34–2.51; p = 0.87). However, an important limitation of this study is that it did not evaluate a potential dose–response association between transfusions and patient outcomes. Additionally, their definition of “perioperative transfusion” was unusually broad, encompassing any transfusion within 90 days before or after major oncologic surgery 5. By contrast, studies demonstrating a clear association between transfusion and adverse oncologic outcomes have typically focused on the immediate perioperative window. For example, Hee et al. 2 evaluated only patients who received transfusion intraoperatively or within 7 days postoperatively and demonstrated a dose-dependent relationship between transfusion volume and both recurrence and mortality. Thus, although emerging literature occasionally challenges restrictive transfusion thresholds, current evidence continues to support restrictive transfusion practices for oncologic patients—particularly in the immediate perioperative period, where the survival impact appears most clinically meaningful. It is important to acknowledge that the literature linking perioperative allogeneic blood transfusion to worse oncologic and non-oncologic outcomes is observational and therefore vulnerable to reverse causality and confounding. Patients who receive transfusions may differ systematically from those who do not. For example, they may have greater comorbidity, more advanced or aggressive disease, baseline anemia, or undergo longer and more complex resections with higher blood loss. In such cases, transfusion may function as a marker of illness severity and operative complexity rather than a direct contributor to adverse outcomes. Accordingly, these associations should be interpreted cautiously, and the potential for reverse causation should be acknowledged when applying these data to transfusion decision-making. As summarized in Table 1, the default perioperative transfusion threshold in otolaryngology head and neck surgery should be restrictive: hemoglobin < 7 g/dL in stable patients, with a higher threshold of < 8 g/dL in those with a history of cardiovascular disease. In patients undergoing free flap reconstruction, the transfusion threshold should similarly be < 7 g/dL, based on studies correlating transfusions with increased risk of perioperative complications. In patients undergoing oncologic surgery, a possible immunomodulatory effect of RBC transfusion on cancer prognosis is poorly understood, but retrospective studies favor a restrictive transfusion threshold < 7 g/dL. Future research should focus on prospective evaluation of transfusion-related immunomodulation in oncologic patients. Carson is level 1 evidence, Hee is level 3 evidence. Dort is level 1 evidence, Dumbill is level 5. Runge is level 3 evidence. The authors have nothing to report. The authors declare no conflicts of interest. Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.
Ponduri et al. (Sat,) studied this question.