Transfusion in critical care: Past, present and future

Does red blood cell transfusion affect clinical outcomes in critically ill patients? A report from a large teaching hospital in south Iran

BACKGROUND

Despite the beneficial effects, RBC transfusion can be associated with infectious and non-infectious complications in critically ill patients.

OBJECTIVES

Investigate current RBC transfusion practices and their effect on the clinical outcomes of patients in intensive care units (ICUs).

DESIGN

Retrospective observational study.

SETTING

Three mixed medical-surgical adult ICUs of a large academic tertiary hospital.

PATIENTS AND METHODS

From March 2018 to February 2020, all adult patients admitted to medical or surgical ICU. Patients who received one or more RBC transfusions during the first month of ICU admission were included in the "transfusion" group, while the remaining patients were assigned to the "non-transfusion" group.

MAIN OUTCOME MEASURES

Mortality and length of ICU and hospital stay.

SAMPLE SIZE

2159 patients.

RESULTS

Of 594 patients who recieved transfusions, 27% of patients received red blood cell (RBC) products. The mean pre-transfusion hemoglobin (Hb) level was 8.05 (1.46) g/dL. There was a significant relationship between higher APACHE II scores and ICU mortality in patients with Hb levels of 7-9 g/dL (OR adjusted=1.05). Also, ICU mortality was associated with age (OR adjusted=1.03), APACHE II score (OR adjusted=1.08), and RBC transfusion (OR adjusted=2.01) in those whose Hb levels were >9 (g/dl).

CONCLUSION

RBC transfusion was associated with an approximately doubled risk of ICU mortality in patients with Hb>9 g/dL. High APACHE II score and age increase the chance of death in the ICU by 8% and 3%, respectively. Hence, ICU physicians should consider a lower Hb threshold for RBC transfusion, and efforts must be made to optimize RBC transfusion practices.

LIMITATIONS

Single-center and retrospective study.

Measuring Mitochondrial Oxygen Tension during Red Blood Cell Transfusion in Chronic Anemia Patients: A Pilot Study

In light of the associated risks, the question has been raised whether the decision to give a blood transfusion should solely be based on the hemoglobin level. As mitochondria are the final destination of oxygen transport, mitochondrial parameters are suggested to be of added value. The aims of this pilot study were to investigate the effect of a red blood cell transfusion on mitochondrial oxygenation as measured by the COMET device in chronic anemia patients and to explore the clinical usability of the COMET monitor in blood transfusion treatments, especially the feasibility of performing measurements in an outpatient setting. To correct the effect of volume load on mitochondrial oxygenation, a red blood cell transfusion and a saline infusion were given in random order. In total, 21 patients were included, and this resulted in 31 observations. If patients participated twice, the order of infusion was reversed. In both the measurements wherein a blood transfusion was given first and wherein 500 mL of 0.9% saline was given first, the median mitochondrial oxygen tension decreased after red blood cell transfusion. The results of this study have strengthened the need for further research into the effect of blood transfusion tissue oxygenation and the potential role of mitochondrial parameters herein.

A CNN-LASSO ensemble classification model for incomplete antibody reactants screening in coombs test

BACKGROUND

Precise classification of incomplete antibody reactants (IAR) in the Coombs test is the primary means to prevent incompatible blood transfusions. Currently, an automatic and contactless method is required for accurate IAR classification to avoid human error.

OBJECTIVE

We present an ensemble learning algorithm that integrates five convolutional neural networks and the least absolute shrinkage and selection operator (LASSO) regression algorithm into an IAR intensity classification model.

METHODS

A dataset including 1628 IAR and corresponding labels of IAR intensity categories ((-), (1+), (2+), (3+), and (4+)) was used. We trained the ensemble model using 1302 IAR and validated its performance using 326 IAR. The optimal ensemble model was used to assist immunologists in classifying IAR. The chord diagrams based on the human-machine interaction were established.

RESULTS

The ensemble model achieved 98.8%, 98.4%, 99.7%, 99.5%, and 99.4% accuracies in the (-), (1+), (2+), (3+), and (4+) categories, respectively. The results were compared with those of manual classification by immunologists (average accuracy: 99.2% vs. 75.6%). Using the model, all three immunologists achieved increased accuracy (average accuracy: +8.4%).

CONCLUSIONS

The proposed algorithm can thus effectively improve the accuracy and efficiency of IAR intensity classification and facilitate the automation of haemolytic disease screening equipment.

Complement C3 activation in the ICU: Disease and therapy as Bonnie and Clyde

Patients in the intensive care unit (ICU) often straddle the divide between life and death. Understanding the complex underlying pathomechanisms relevant to such situations may help intensivists select broadly acting treatment options that can improve the outcome for these patients. As one of the most important defense mechanisms of the innate immune system, the complement system plays a crucial role in a diverse spectrum of diseases that can necessitate ICU admission. Among others, myocardial infarction, acute lung injury/acute respiratory distress syndrome (ARDS), organ failure, and sepsis are characterized by an inadequate complement response, which can potentially be addressed via promising intervention options. Often, ICU monitoring and existing treatment options rely on massive intervention strategies to maintain the function of vital organs, and these approaches can further contribute to an unbalanced complement response. Artificial surfaces of extracorporeal organ support devices, transfusion of blood products, and the application of anticoagulants can all trigger or amplify undesired complement activation. It is, therefore, worth pursuing the evaluation of complement inhibition strategies in the setting of ICU treatment. Recently, clinical studies in COVID-19-related ARDS have shown promising effects of central inhibition at the level of C3 and paved the way for prospective investigation of this approach. In this review, we highlight the fundamental and often neglected role of complement in the ICU, with a special focus on targeted complement inhibition. We will also consider complement substitution therapies to temporarily counteract a disease/treatment-related complement consumption.