Transfusion Decision Making in Pediatric Critical Illness

Transfusion strategies for neonates: current perspectives

Background

Blood transfusion intervention has been proven to be a crucial therapeutic aid for preterm infants with serious morbidities such as sepsis, intraventricular hemorrhage, and cardiopulmonary insufficiencies. However, blood transfusion practices have also been shown to cause significant adverse outcomes, which may negate the therapeutic effect of the intervention. To address the varying policies regarding the administration of blood products, healthcare professionals have adopted a consensus-based approach. The absence of a standard protocol has resulted in conflicting outcomes in previous clinical studies.

Objective

This study aimed to evaluate the effectiveness of blood transfusion practices in preterm infants by analyzing past clinical research and identifying the current trends that have emerged as a result of recent trials.

Results

Recent trials have demonstrated comparable trends in mortality rates and other primary outcomes, including retinopathy of prematurity, intraventricular hemorrhage, bronchopulmonary dysplasia, and brain injury, following transfusion of blood products in both groups. Nevertheless, employing restrictive thresholds rather than adopting a liberal approach can reduce these outcomes.

Conclusion

The current literature does not provide clear support for either technique as opposing and contradictory results are evident. However, there is a slight inclination toward the restrictive transfusion threshold due to recent trials, which warrants further in-depth investigation into this issue.

Effects of Different Hemoglobin Levels on Near-Infrared Spectroscopy-Derived Cerebral Oxygen Saturation in Elderly Patients Undergoing Noncardiac Surgery

Background

Near-infrared spectroscopy (NIRS) is a commonly used technique to evaluate tissue oxygenation and prevent harmful cerebral desaturation in the perioperative setting. The aims of the present study were to assess whether surgery-related anemia can be detected via NIRS of cerebral oxygen saturation and to investigate the effects of different perioperative transfusion strategies on cerebral oxygenation, potentially affecting transfusion decision-making.

Study Design and Methods

Data from the ongoing multicenter LIBERAL-Trial (liberal transfusion strategy to prevent mortality and anemia-associated ischemic events in elderly noncardiac surgical patients, LIBERAL) were used. In this single-center sub-study, regional cerebral oxygenation saturation (rSO2) was evaluated by NIRS at baseline, pre-, and post-RBC transfusion. The obtained values were correlated with blood gas analysis-measured Hb concentrations.

Results

rSO2 correlated with Hb decline during surgery (r = 0.35, p < 0.0001). Different RBC transfusion strategies impacted rSO2 such that higher Hb values resulted in higher rSO2. Cerebral desaturation occurred at lower Hb values more often.

Discussion

Cerebral oxygenation monitoring using NIRS provides noninvasive rapid and continuous information regarding perioperative alterations in Hb concentration without the utilization of patients' blood for blood sampling. Further investigations are required to demonstrate if cerebral rSO2 may be included in future individualized transfusion decision strategies.

Postoperative Hematocrit and Adverse Outcomes in Pediatric Cardiac Surgery Patients: A Cross-Sectional Study From the Society of Thoracic Surgeons and Congenital Cardiac Anesthesia Society Database Collaboration

BACKGROUND

We sought to examine potential associations between pediatric postcardiac surgical hematocrit values and postoperative complications or mortality.

METHODS

A retrospective, cross-sectional study from the Society of Thoracic Surgeons Congenital Heart Surgery Database (STS-CHSD) and Congenital Cardiac Anesthesia Society Database Module (2014-2019) was completed. Multivariable logistic regression models, adjusting for covariates in the STS-CHSD mortality risk model, were used to assess the relationship between postoperative hematocrit and the primary outcomes of operative mortality or any major complication. Hematocrit was assessed as a continuous variable using linear splines to account for nonlinear relationships with outcomes. Operations after which the oxygen saturation is typically observed to be <92% were classified as cyanotic and ≥92% as acyanotic.

RESULTS

In total, 27,462 index operations were included, with 4909 (17.9%) being cyanotic and 22,553 (82.1%) acyanotic. For cyanotic patients, each 5% incremental increase in hematocrit over 42% was associated with a 1.31-fold (95% confidence interval [CI], 1.10-1.55; P = .003) increase in the odds of operative mortality and a 1.22-fold (95% CI, 1.10-1.36; P < .001) increase in the odds of a major complication. For acyanotic patients, each 5% incremental increase in hematocrit >38% was associated with a 1.45-fold (95% CI, 1.28-1.65; P < .001) increase in the odds of operative mortality and a 1.21-fold (95% CI, 1.14-1.29; P < .001) increase in the odds of a major complication.

CONCLUSIONS

High hematocrit on arrival to the intensive care unit (ICU) is associated with increased operative mortality and major complications in pediatric patients following cardiac surgery.

Near Infrared Spectroscopy in Anemia Detection and Management: A Systematic Review

Red cell transfusions are intended to improve oxygen delivery to tissues. Although studies comparing hemoglobin concentration triggers for transfusion have been done, the hemoglobin threshold for clinical benefit remains uncertain. Direct measurement of tissue oxygenation with non-invasive near infrared spectroscopy has been proposed as a more physiological transfusion trigger, but its clinical role remains unclear. This systematic review examined the role of near infrared spectroscopy for detection of anemia and guiding transfusion decisions. Abstracts were identified up until May 2019 through searches of PubMed, EMBASE and The Web of Science. There were 69 studies meeting the inclusion criteria, most (n = 65) of which were observational studies. Tissue oxygen saturation had been measured in a wide range of clinical settings, with neonatal intensive care (n = 26) and trauma (n = 7) being most common. Correlations with hemoglobin concentration and tissue oxygenation were noted and there were correlations between changes in red cell mass and changes in tissue oxygenation through blood loss or transfusion. The value of tissue oxygenation for predicting transfusion was determined in only four studies, all using muscle oxygen saturation in the adult trauma setting. The overall sensitivity was low at 34% (27%-42%) and while it had better specificity at 78% (74%-82%), differing and retrospective approaches create a high level of uncertainty with respect to these conclusions. There were four prospective randomized studies involving 540 patients, in cardiac and neurological surgery and in neonates that compared near infrared spectroscopy to guide transfusion decisions with standard practice. These showed a reduction in the number of red cells transfused per patient (OR: 0.44 [0.09-0.79]), but not the number of patients who received transfusion (OR: 0.71 [0.46-1.10]), and no change in clinical outcomes. Measuring tissue oxygen saturation has potential to help guide transfusion; however, there is a lack of data upon which to recommend widespread implementation into clinical practice. Standardization of measurements is required and greater research into levels at which tissue oxygenation may lead to adverse clinical outcomes would help in the design of future clinical trials.

Transfusion in children with acute respiratory distress syndrome

Transfusion is a frequent treatment in pediatric patients with acute respiratory distress syndrome (PARDS) although evidence to support transfusion decision-making is lacking. The purpose of this review is to review the current state of knowledge on the issue of transfusion in children with PARDS and to detail the possible beneficial effects and potential deleterious impacts of transfusion in this patient population. Based on the current literature and recent guidelines, a restrictive red blood cell (RBC) transfusion strategy (avoidance of transfusion when the haemoglobin level is above 7 g/dL) is indicated in stable patients without severe PARDS, as these were excluded from the large trials. In children with severe PARDS, further research is needed to determine if factors other than the haemoglobin level might guide RBC transfusion decision-making by better characterizing the presence of low oxygen delivery (DO₂). Additionally, appropriate indications for prophylactic transfusion of hemostatic products (plasma or platelets) in children with PARDS are lacking.

Pediatric trauma transfusion and cognitive aids

PURPOSE OF REVIEW

Trauma is the most common cause of pediatric mortality. Much of the research that led to life-saving interventions in adults, however, has not been replicated in the pediatric population. Children have important physiologic and anatomic differences from adults, which impact hemostasis and transfusion. Hemorrhage is a leading cause of death in trauma, and children have important differences in their coagulation profiles. Transfusion strategies, including the massive transfusion protocol and use of antifibrinolytics, are still controversial. In addition to the blood that is lost from the injury itself, trauma leads to inflammation and to a dysfunction in hemostasis, causing coagulopathy.

RECENT FINDINGS

In one study in which children suffered from mainly blast and penetrating injuries in a combat setting (PEDTRAX trial), the early administration of tranexamic acid was associated with decreased mortality. Some authors suggest that this result may not apply to blunt trauma, which is much more common in children in noncombat settings. Using thromboelastography to guide the administration of recombinant Factor VIIa has been done in selected cases and may represent a future avenue of research.

SUMMARY

This article explores new research from the past year in pediatric trauma, starting with the physiologic differences in pediatric red blood cells and coagulation profiles. We also looked at the dramatic change in thinking over the past decade in the tolerable level of anemia in critically ill pediatric patients, as well as scales for determining the need for massive transfusion and exploring if the concepts of damage control resuscitation apply to children. Other strategies, such as avoiding hypothermia, and the selective administration of antifibriniolytics, are important in pediatric trauma as well. Future research that is pediatric focused is needed for the optimal care of our youngest patients.

Serum iron levels are an independent predictor of in-hospital mortality of critically ill patients: a retrospective, single-institution study

Objective

This study aimed to examine the relationship between serum iron levels and in-hospital mortality in critically ill patients.

Methods

We retrospectively studied 250 critically ill patients who received treatment at the intensive care unit between June 2015 and May 2017. Blood chemistry and hepatic and renal function were measured. Kaplan–Meier survival curves were plotted according to serum iron levels. Correlations between serum iron levels and other variables were analyzed.

Results

A total of 165 (66.0%) patients had abnormally low serum iron levels (<10.6 μmol/L). Patients who died during hospitalization had markedly higher Acute Physiology and Chronic Health Evaluation II scores and significantly lower serum iron levels compared with those who survived. Cumulative survival was significantly lower in patients with low serum iron levels than in those with normal serum iron levels in subgroup analysis of older patients (n = 192). Multivariate regression analysis showed that, after adjusting for relevant factors, low serum iron levels remained an independent risk for in-hospital mortality (odds ratio 2.014; 95% confidence interval 1.089, 3.725).

Conclusions

Low serum iron levels are present in a significant proportion of critically ill patients and are associated with higher in-hospital mortality, particularly in older patients.