When to transfuse?

Myron Yaster MD, Nina Deutsch MD, and Eugenie “Genie” Heitmiller, MD, FAAP

In yesterday's reposted PAAD, the pathophysiology of hemorrhagic shock was discussed with an eye to future therapies.  In today’s PAAD we review another article on perioperative red blood cell transfusion therapy in pediatric patients.  The senior author, Dr. Susan Goobie of the Boston Children’s Hospital, has written extensively on this topic and has become one of our pediatric anesthesia community’s go-to experts on this issue.  I’ve asked Drs. Genie Heitmiller and Nina Deutsch from Children’s National Medical Center in Washington DC, who have extensive institutional and national expertise on this topic to assist me.

Why is this even an issue?  Because “there ain’t no such thing as a free lunch”.  When to transfuse red blood cells in the pediatric perioperative period is a question every one of you faces daily and for which there is little evidence-based science to guide us. As we saw in yesterday’s PAAD, on the one hand red blood cells are needed to carry oxygen and to prevent ischemia and end-organ dysfunction.  On the other hand, transfusion comes with a price, namely, infection, respiratory complications, increased transplant graft failure, alloimmunization, prolonged hospital stays, multiorgan failure, increased health-care costs, and death.  How to balance these opposing “hands” and get the upper hand is the theme of today’s PAAD but first we need some guidance from George Castanza (Seinfeld):I  Myron Yaster MD

Clinical focus review article

Downey LA, Goobie SM.  Perioperative Pediatric Erythrocyte Transfusions: Incorporating Hemoglobin Thresholds and Physiologic Parameters in Decision-making.  Anesthesiology. 2022 Nov 1;137(5):604-619. PMID: 36264089

In adult patients “the ‘tolerance of anemia’, has reduced allogeneic erythrocyte transfusions, hospital costs, and adverse events.”1, 2 “In a landmark trial in pediatric intensive care patients, TRansfusion strategies for patients In Pediatric Intensive Care Units (TRIPICU), Lacroix et al.3 demonstrated that a restrictive strategy reduced erythrocyte transfusions by 44% with no increase in mortality compared to more liberal transfusion strategies.”1  But let’s face it, in the OR, blood loss from surgery is acute, dynamic, and often on-going and to our view is not really equivalent to what happens in the ICU.  In today’s PAAD, Downey and Goobie provide us with hemoglobin and physiologic transfusion triggers for the pediatric anesthesiologist.

Preoperative Assessment

Routine preoperative hemoglobin and urinalysis laboratory testing in pediatrics is usually unnecessary.4, 5  However, for surgical procedures in which major blood loss is expected, for example patients undergoing major orthopedic, cardiac, liver transplant, or craniosynostosis surgery, we think that preoperative hemoglobin testing is appropriate and, if anemia is found, treatment with iron or erythropoietin for several weeks before surgery makes sense.

Pediatric Patients with Massive Hemorrhage or Critical Bleeding

We’ve discussed massive hemorrhage defined as blood loss and/or transfusion of more than 40 ml/kg without or without hemodynamic instability in several recent PAADs.  The recommendations are to transfuse red blood cells, plasma, and platelets in a 1:1:1 ratio (or a 2:1:1 ratio) until the bleeding is no longer life threatening.  “Expert consensus suggest maintaining hemoglobin level in the range of 7.0 to 8.0 g/dL in children and 9.0 to 10.0 g/dL in neonates.”1

Pediatric Noncardiac Surgical Patients

From the adult literature, “restrictive” (7 or 8 g/dL) hemoglobin thresholds are often compared to “liberal” thresholds (9 or 10 g/dL) across a wide variety of clinical scenarios, critical illness, and surgical procedures.  There isn’t a lot of evidence-based science to guide us perioperatively in pediatrics. In the PICU, “restrictive erythrocyte transfusion strategies for management of the critically ill child recommended by expert group consensus guidelines are as follows: (1) consideration of erythrocyte transfusion in the hemodynamically stable critically ill pediatric patient based on clinical judgement for a hemoglobin level of 5.0 to 7.0 g/dL, (2) transfusion is not necessary for pediatric patients with hemoglobin level greater than 7.0 g/dL, and (3) transfusion is advised against for a hemoglobin greater than 9.0 g/dL. These recommendations pertain to the children with the following conditions: critical illness, postsurgery or postprocedural, respiratory failure, sepsis, non–life-threatening bleeding, or renal replacement therapy. These recommendations exclude children with the following conditions: acute brain injury, oncologic disease, stem cell transplantation, hemolytic anemia, sickle cell anemia, severe acute respiratory distress syndrome, mechanical support, or cardiac disease. Such high-risk patients may require higher transfusion targets (hemoglobin levels between 7.0 and 10.0 g/dL), guided by physiologic parameters and clinical judgement.”1

Pediatric Cardiac Surgical Patients

“Expert consensus recommends an on-CPB hemoglobin target of 8 g/dL or higher for acyanotic pediatric patients undergoing biventricular repair; however, there is currently not enough outcome data to make recommendations regarding on-CBP targets in cyanotic patients.  Minimizing CPB prime volumes can reduce the need for blood product transfusions in pediatric patients undergoing cardiac surgery.”1  “Current expert consensus recommends a postoperative hemoglobin transfusion threshold in stable, acyanotic cardiac patients with hemoglobin levels greater than 7.0 or 8.0 g/dL in the presence of signs of symptomatic anemia (grade IB evidence). For stable, cyanotic cardiac children without signs of symptomatic anemia, the recommended postoperative transfusion threshold is a hemoglobin level greater than 9.0 g/dL (grade 1C).”1  The PAAD’s cardiac anesthesia review team has addressed some of these recommendations and have advocated for the use of fresh whole blood to minimize blood loss.

Moving Away from Hemoglobin Numbers to Incorporating Physiologic Parameters

Perhaps targeting a specific hemoglobin value is not the way to determine transfusion therapy and goals. Rather, we should be targeting the consequences of anemia by looking for evidence of intracellular hypoxia and ischemia, by following serial blood lactates, base deficits, and pH to guide how and when we transfuse.  In previous PAADs discussing hypotension we’ve discussed methods of monitoring cerebral and somatic perfusion, oxygen delivery and consumption using NIRs, PRx, etc.  Should we be using these technologies during intraoperative hemorrhage to guide red blood cell replacement therapy instead of relying on hemoglobin values?  Clearly this is an area for future research.  What do you do in your practice?

References

1.           Downey LA, Goobie SM. Perioperative Pediatric Erythrocyte Transfusions: Incorporating Hemoglobin Thresholds and Physiologic Parameters in Decision-making. Anesthesiology. Nov 1 2022;137(5):604-619. doi:10.1097/aln.0000000000004357

2.           Spahn DR, Muñoz M, Klein AA, Levy JH, Zacharowski K. Patient Blood Management: Effectiveness and Future Potential. Anesthesiology. Jul 2020;133(1):212-222. doi:10.1097/aln.0000000000003198

3.           Lacroix J, Hébert PC, Hutchison JS, et al. Transfusion strategies for patients in pediatric intensive care units. The New England journal of medicine. Apr 19 2007;356(16):1609-19. doi:10.1056/NEJMoa066240

4.           O'Connor ME, Drasner K. Preoperative laboratory testing of children undergoing elective surgery. AnesthAnalg. 1990 1990;70(2):176-180. Not in File.

5.           Patel RI, DeWitt L, Hannallah RS. Preoperative laboratory testing in children undergoing elective surgery: analysis of current practice. JClinAnesth. 1997 1997;9(7):569-575. Not in File.