Hemodilution and anemia in patients with cardiac disease: what is the safe limit?

Acute Hemodilution is Safe in Patients with Comorbid Illness Undergoing Partial Hepatectomy

Despite increased use of acute hemodilution (AH) to reduce perioperative blood transfusion in patients undergoing partial hepatectomy, there is a lack of data on safety in those with comorbid medical illness. We performed a retrospective review of 96 patients undergoing partial hepatectomy with AH and low central venous pressure (CVP) anesthesia. The cohort was compared with 63 patients undergoing partial hepatectomy using standard anesthetic management (SA) and low CVP anesthesia. All were American Society of Anesthesiologists physical status 3 or 4. 58 per cent were baseline hypertensive on medication. Hepatic resection was predominantly performed for metastatic colorectal (41%) and primary hepatic (32%) cancer. Forty per cent underwent major hepatectomy. The mean volume of blood removed for AH was 497 mL (range, 0 to 1 L). Most achieved low CVP (AH 90% vs SA 84%, P = 0.3). Blood loss was lower with AH (mean 480 mL vs 904 mL, P < 0.001). Blood transfusion rate was 74 per cent lower with AH ( P < 0.001). There was no difference in cardiac, respiratory, renal, or overall complications with AH compared with SA. Acute hemodilution is well tolerated by patients with comorbid illness undergoing partial hepatectomy, favoring ongoing use and further study.

Avoidance of Blood Transfusion to Patients Suffering From Myocardial Injury and Severe Anemia Is Associated With Increased Long-Term Mortality: A Retrospective Cohort Analysis

Myocardial injury and anemia are common among patients in internal medicine departments. Nevertheless, the level of anemia in which blood should be given to these patients is ill defined. We conducted a retrospective, cohort analysis. A total of 209 patients hospitalized to internal medicine, with myocardial injury (troponin I > 0.2 mcg/L, not diagnosed as ACS, acute coronary syndrome) and anemia (Hb < 10 g/dL, without overt bleeding) were included. The overall in-hospital mortality rate was 20.7%. A total of 37 patients (17.8%) had severe anemia (Hb < 8 g/dL). A total of 73 patients (34.9%) were transfused. Severe anemia was not associated with increased long-term mortality in the whole cohort while survival of patients with severe anemia that were not transfused was significantly reduced compared to transfused patients (44% vs 80%; P = 0.03). Mortality rates were similar for all patients with Hb ≥ 8 g/dL, regardless of transfusion (54% vs 49%; P = 0.60). Consistently, lack of blood transfusion in patients with severe anemia was independently associated with a 2.27 (1.08-4.81) greater adjusted risk of all-cause mortality (P-value for interaction = 0.04), whereas it did not significantly increase in patients with Hb ≥ 8 g/dL. Avoidance of blood transfusion is associated with unfavorable outcomes among patients with myocardial injury and severe anemia.

Perioperative Red Blood Cell Transfusion: Harmful or Beneficial to the Patient?

Although the transfusion of red blood cells (RBCs) is safer than ever regarding infections, it is still associated with several adverse reactions and therefore should only be used on the basis of evidence-based triggers. However, prevention of RBC transfusion and subsequent substitution of blood losses with acellular solutions will inevitably result in dilutional anemia. Acute dilutional anemia can be compensated by the body over a wide range of hemoglobin concentrations without a critical restriction of tissue oxygenation. On the other hand, chronic anemia is known to be a potent cause of morbidity and mortality. As a consequence, the impact of perioperative anemia on mortality is difficult to describe, because anemia, as well as the transfusion of RBCs, can influence the clinical outcome. The resulting 'Gordian knot' cannot be cut easily, and this circumstance forces clinical physicians to make a daily trade-off between transfusion-associated and anemia-associated risks. This review focuses on the physiology of oxygen transport, the hazards of acute anemia, the hazards of RBC transfusion, and the literature putting these problems into perspective.