Impact of red blood cell transfusion on global and regional measures of oxygenation

Impact of Different Red Blood Cell Storage Solutions and Conditions on Cell Function and Viability: A Systematic Review

Red blood cell (RBC) storage solutions have evolved significantly over the past decades to optimize the preservation of cell viability and functionality during hypothermic storage. This comprehensive review provides an in-depth analysis of the effects of various storage solutions and conditions on critical RBC parameters during refrigerated preservation. A wide range of solutions, from basic formulations such as phosphate-buffered saline (PBS), to advanced additive solutions (ASs), like AS-7 and phosphate, adenine, glucose, guanosine, saline, and mannitol (PAGGSM), are systematically compared in terms of their ability to maintain key indicators of RBC integrity, including adenosine triphosphate (ATP) levels, morphology, and hemolysis. Optimal RBC storage requires a delicate balance of pH buffering, metabolic support, oxidative damage prevention, and osmotic regulation. While the latest alkaline solutions enable up to 8 weeks of storage, some degree of metabolic and morphological deterioration remains inevitable. The impacts of critical storage conditions, such as the holding temperature, oxygenation, anticoagulants, irradiation, and processing methods, on the accumulation of storage lesions are also thoroughly investigated. Personalized RBC storage solutions, tailored to individual donor characteristics, represent a promising avenue for minimizing storage lesions and enhancing transfusion outcomes. Further research integrating omics profiling with customized preservation media is necessary to maximize post-transfusion RBC survival and functions. The continued optimization of RBC storage practices will not only enhance transfusion efficacy but also enable blood banking to better meet evolving clinical needs.

Patient Blood Management as an Emerging Concept in Quality: The Role of Nurses

BACKGROUND

Transfusion of blood components has long been considered lifesaving therapy. While blood transfusion may be clinically indicated as a treatment option for some patients, the benefits of transfusion in asymptomatic, hemodynamically stable patients are questionable.

PROBLEM

Blood component transfusion is routinely used as a default therapy when not clinically indicated, increasing the risk of poor patient outcomes, adverse events, pressures on blood supply and availability, and increased health care costs.

APPROACH

Nurses have the responsibility to advocate for patients and reduce/avoid unnecessary blood transfusion through the implementation of patient blood management (PBM). The PBM paradigm includes treatment of anemia, minimizing blood loss and bleeding, optimization of coagulation, and employing true patient-centered decision making.

CONCLUSIONS

PBM should become the standard of care with the goal of improving health care quality and patient outcomes while using the multidisciplinary team for its implementation. As advocates for their patients, nurses can play a major role in the development, implementation, and promotion of PBM.

Validation of a human paper-based blood typing method for use in pet pigs

BACKGROUND

Evidence-based medical practices for pet pigs are needed. EldonCard is a human blood-typing card shown to be rapid and reliable in identifying blood phenotypes of pet pigs. The objective of this study was to validate EldonCard by determining its reliability, reproducibility, and robustness for its routine use in the clinical setting.

KEY FINDINGS

Twenty-four venous blood samples from pet pigs were collected for a prospective in vitro study. Blood genotypes ("EAAA0 " and "EAA00 ") were identified in 15 samples via polymerase chain reaction (PCR). All samples were phenotyped ("A," "Aweak ," and "0" or "-") via EldonCard. Kappa (κ) statistics measured the level of agreement between 2 raters, and between EldonCard and PCR. McNemar's test determined if an association between the blood types and EldonCard or PCR exists, with significance at P < 0.05. Agreement between raters and methods was perfect (60/60 [100%], κ:1, P < 0.001; 15/15 [100%], κ:1, P < 0.001). There was no difference in the proportions of blood groups based on method.

SIGNIFICANCE

In conjunction with previous data, EldonCard is a rapid, accurate, reliable, precise, and robust in-clinic blood-typing method for the A0 system of pet pigs. EldonCard is now a validated blood-typing tool for the A0 system of pet pigs and maybe used for pretransfusion screenings and identification of donors and recipients.

Development and validation of a nomogram for blood transfusion during intracranial aneurysm clamping surgery: a retrospective analysis

PURPOSE

Intraoperative blood transfusion is associated with adverse events. We aimed to establish a machine learning model to predict the probability of intraoperative blood transfusion during intracranial aneurysm surgery.

METHODS

Patients, who underwent intracranial aneurysm surgery in our hospital between January 2019 and December 2021 were enrolled. Four machine learning models were benchmarked and the best learning model was used to establish the nomogram, before conducting a discriminative assessment.

RESULTS

A total of 375 patients were included for analysis in this model, among whom 108 received an intraoperative blood transfusion during the intracranial aneurysm surgery. The least absolute shrinkage selection operator identified six preoperative relative factors: hemoglobin, platelet, D-dimer, sex, white blood cell, and aneurysm rupture before surgery. Performance evaluation of the classification error demonstrated the following: K-nearest neighbor, 0.2903; logistic regression, 0.2290; ranger, 0.2518; and extremely gradient boosting model, 0.2632. A nomogram based on a logistic regression algorithm was established using the above six parameters. The AUC values of the nomogram were 0.828 (0.775, 0.881) and 0.796 (0.710, 0.882) in the development and validation groups, respectively.

CONCLUSIONS

Machine learning algorithms present a good performance evaluation of intraoperative blood transfusion. The nomogram established using a logistic regression algorithm showed a good discriminative ability to predict intraoperative blood transfusion during aneurysm surgery.

Effects of Hydroxyurea on Skeletal Muscle Energetics and Function in a Mildly Anemic Mouse Model

Hydroxyurea (HU) is a ribonucleotide reductase inhibitor most commonly used as a therapeutic agent in sickle cell disease (SCD) with the aim of reducing the risk of vaso-occlusion and improving oxygen transport to tissues. Previous studies suggest that HU may be even beneficial in mild anemia. However, the corresponding effects on skeletal muscle energetics and function have never been reported in such a mild anemia model. Seventeen mildly anemic HbAA Townes mice were subjected to a standardized rest-stimulation (transcutaneous stimulation)-protocol while muscle energetics using 31Phosphorus magnetic resonance spectroscopy and muscle force production were assessed and recorded. Eight mice were supplemented with hydroxyurea (HU) for 6 weeks while 9 were not (CON). HU mice displayed a higher specific total force production compared to the CON, with 501.35 ± 54.12 N/mm3 and 437.43 ± 57.10 N/mm3 respectively (+14.6%, p &lt; 0.05). Neither the total rate of energy consumption nor the oxidative metabolic rate were significantly different between groups. The present results illustrated a positive effect of a HU chronic supplementation on skeletal muscle function in mice with mild anemia.

Impact of RBC Transfusion on Peripheral Capillary Oxygen Saturation and Partial Pressure of Arterial Oxygen

OBJECTIVES

RBCs are known to undergo deleterious changes during storage, known as storage lesions, which have been shown to result in decreased oxygen-carrying capacity. However, there is inadequate literature describing the effects of stored RBC allogeneic transfusion on oxygen parameters in vivo. The oxygen standard parameters were retrospectively assessed before and after RBC transfusion.

METHODS

Patients who received 1 RBC transfusion were assessed for hemoglobin (Hb) levels, peripheral capillary oxygen saturation (Spo2), and partial pressure of arterial oxygen (Pao2) from 12 hours before and 24 hours after transfusion.

RESULTS

In total, 78 patients who were monitored by Spo2 and 28 patients monitored by Pao2 were included in this analysis. Following RBC transfusion, Hb levels increased significantly (P < .001); however, there was a significant decrease in both Spo2 and Pao2 within 24 hours after transfusion (P = .04 and P = .003, respectively), indicating lower tissue oxygenation and lower soluble oxygen level.

CONCLUSIONS

This single-center, retrospective study revealed evidence of significantly decreased oxygenation and tissue perfusion after single-unit RBC transfusion, despite corrected Hb levels.

Anemia of Prematurity and Oral Feeding Milestones in Premature Infants

OBJECTIVE

Anemia of prematurity (AOP) and oral feeding problems are common in premature infants. This study aimed to determine the influence of AOP on aerodigestive outcomes and the duration to full Per Oral (PO).

STUDY DESIGN

Prospectively collected data on premature infants who initiated oral feeds at ≤ 34 weeks' postmenstrual age were examined. Infants were categorized into "AOP+" and "AOP-" based on hematocrit at initial PO, that is, < 29 or ≥ 29%.

RESULTS

Forty-four infants in AOP+ compared with 74 in AOP-. AOP+ infants had lower birth gestation and weight (p < 0.001). The anthropometrics at initial PO were similar. AOP+ had lower mean hematocrit and higher oxygen need at initial PO, and at full PO (p < 0.05). AOP+ reached full PO at a later gestation and took longer days from initial PO to full PO (p < 0.01). BPD, intraventricular hemorrhage (IVH ≤ 2), and hospital stay were greater in the AOP+ (p < 0.05). After adjusting for covariates, initial PO hematocrit was not predictive of time to full PO [hazard ratio 1.3 (CI 0.88-2.0), p = 0.18].

CONCLUSION

AOP is not independently associated with the duration to full PO. Supplemental oxygen for associated comorbidities may have compensated for the underlying anemia.

Intraoperative blood loss may be associated with myocardial injury after non-cardiac surgery

BACKGROUND

This study aimed to evaluate the association between intraoperative blood loss and myocardial injury after non-cardiac surgery (MINS), which is a severe and common postoperative complication.

METHODS

We compared the incidence of MINS based on significant intraoperative bleeding, defined as an absolute hemoglobin level < 7 g/dL, a relative hemoglobin level less than 50% of the preoperative measurement, or need for packed red cell transfusion. We also estimated a threshold for intraoperative hemoglobin level associated with MINS.

RESULTS

We stratified a total of 15,926 non-cardiac surgical patients with intraoperative hemoglobin and postoperative cardiac troponin (cTn) measurements according to the occurrence of significant intraoperative bleeding; 13,416 (84.2%) had no significant bleeding while 2,510 (15.8%) did have significant bleeding. After an adjustment with inverse probability weighting, the incidence of MINS was higher in the significant bleeding group (35.2% vs. 16.4%; odds ratio, 1.58; 95% confidence interval, 1.43-1.75; p < 0.001). The threshold of intraoperative hemoglobin associated with MINS was estimated to be 9.9 g/dL with an area under the curve of 0.643.

CONCLUSION

Intraoperative blood loss appeared to be associated with MINS. Further studies are needed to confirm these findings.

CLINICAL REGISTRATION

The cohort was registered before patient enrollment at https://cris.nih.go.kr (KCT0004244).

Venoarterial extra corporeal membrane oxygenation and blood component usage in pediatric patients undergoing cardiac surgery: Single centre experience

Background

Extra Corporeal Membrane Oxygenation (ECMO) is a well-known tool for providing life-saving support in patients developing post cardiotomy cardiogenic shock in post cardiac surgeries. The current study was designed to evaluate blood transfusion requirements and its relation to mortality in neonate and pediatric cardiac patients requiring venoarterial cardiac ECMO during post-operative period following cardiac surgery.

Materials and Methods

Overall 24 pediatric patients (including neonates) who underwent VA ECMO in post cardiac surgery at our institute from January 2016 to October 2017 were included in the study. The details of demographics, blood transfusion, ECMO, and morbidity and mortality were collected for all the patients.

Objective of the Study

The primary objective of our study was to assess the outcome of patients on ECMO in post pediatric cardiac surgery. The secondary objective of the study was to assess the effect of blood transfusion on the outcome of the patients.

Results

Overall mortality rate was 50% (n = 12). The overall transfusion rate of packed red blood cells was higher in patients who did not survive even after institution of VA ECMO. The transfusion of other blood products like platelets, cryoprecipitate, and fresh frozen plasma were also higher in this group of patients though it was statistically non-significant except for packed red cell transfusion. Though statistically non-significant, the patients who didn't survive even after institution of VA ECMO post-surgery had relatively higher mean age (703.88 ± 998.94 days) as compared to their counterparts (510.63 ± 384.36 days).

Conclusion

The use of ECMO is associated with considerable morbidity and mortality. Packed red cell transfusion is definitely higher in expired patients, indicative of deteriorated status of the patient. However, considering non-significant association of other blood components, except packed red cell it is recommended that patients' overall clinical condition should be taken into consideration for transfusion of blood products and not only targeting the transfusion triggers.

Exposure to acute normobaric hypoxia results in adaptions of both the macro- and microcirculatory system

Although acute hypoxia is of utmost pathophysiologic relevance in health and disease, studies on its effects on both the macro- and microcirculation are scarce. Herein, we provide a comprehensive analysis of the effects of acute normobaric hypoxia on human macro- and microcirculation. 20 healthy participants were enrolled in this study. Hypoxia was induced in a normobaric hypoxia chamber by decreasing the partial pressure of oxygen in inhaled air stepwisely (pO₂; 21.25 kPa (0 k), 16.42 kPa (2 k), 12.63 kPa (4 k) and 9.64 kPa (6 k)). Macrocirculatory effects were assessed by cardiac output measurements, microcirculatory changes were investigated by sidestream dark-field imaging in the sublingual capillary bed and videocapillaroscopy at the nailfold. Exposure to hypoxia resulted in a decrease of systemic vascular resistance (p < 0.0001) and diastolic blood pressure (p = 0.014). Concomitantly, we observed an increase in heart rate (p < 0.0001) and an increase of cardiac output (p < 0.0001). In the sublingual microcirculation, exposure to hypoxia resulted in an increase of total vessel density, proportion of perfused vessels and perfused vessel density. Furthermore, we observed an increase in peripheral capillary density. Exposure to acute hypoxia results in vasodilatation of resistance arteries, as well as recruitment of microvessels of the central and peripheral microcirculation. The observed macro- and microcirculatory effects are most likely a result from compensatory mechanisms to ensure adequate tissue oxygenation.

A Physiologic Approach to Hemodynamic Monitoring and Optimizing Oxygen Delivery in Shock Resuscitation

The approach to shock resuscitation focuses on all components of oxygen delivery, including preload, afterload, contractility, hemoglobin, and oxygen saturation. Resuscitation focused solely on preload and fluid responsiveness minimizes other key elements, resulting in suboptimal patient care. This review will provide a physiologic and practical approach for the optimization of oxygen delivery utilizing available hemodynamic monitoring technologies. Venous oxygen saturation (SvO₂) and lactate will be discussed as indicators of shock states and endpoints of resuscitation within the framework of resolving oxygen deficit and oxygen debt.

Influence of intraoperative oxygen content on early postoperative graft dysfunction in living donor liver transplantation: A STROBE-compliant retrospective observational study

The aim of the present study was to investigate the role of intraoperative oxygen content on the development of early allograft dysfunction (EAD) in patients undergoing living donor liver transplantation (LDLT).This retrospective review included 452 adult patients who underwent elective LDLT. Our study population was classified into 2 groups: EAD and non-EAD. Arterial blood gas analysis was routinely performed 3 times during surgery: during the preanhepatic phase (ie, immediately after anesthetic induction); during the anhepatic phase (ie, at the onset of hepatic venous anastomosis); and during the neohepatic phase (ie, 1 hour after graft reperfusion). Arterial oxygen content (milliliters per deciliters) was derived using the following equation: (1.34 × hemoglobin [gram per deciliters] × SaO2 [%] × 0.01) + (0.0031 × PaO2 [mmHg]).The incidence of EAD occurrence was 13.1% (n = 59). Although oxygen contents at the preanhepatic phase were comparable between the 2 groups, the oxygen contents at the anhepatic and neohepatic phases were lower in the EAD group than in the non-EAD group. Patients with postoperative EAD had lower oxygen content immediately before and continuously after graft reperfusion, compared to patients without postoperative EAD. After the preanhepatic phase, oxygen content decreased in the EAD group but increased in the non-EAD group. The oxygen content and prevalence of normal oxygen content gradually increased during surgery in the non-EAD group, but not in the EAD group. Multivariable analysis revealed that oxygen content during the anhepatic phase and higher preoperative CRP levels were factors independently associated with the occurrence of EAD (area under the receiver-operating characteristic curve: 0.754; 95% confidence interval: 0.681-0.826; P < .001 in the model). Postoperatively, patients with EAD had a longer duration of hospitalization, higher incidences of acute kidney injury and infection, and experienced higher rates of patient mortality, compared to patients without EAD.Lower arterial oxygen concentration may negatively impact the functional recovery of the graft after LDLT, despite preserved hepatic vascular flow. Before graft reperfusion, the levels of oxygen content components, such as hemoglobin content, PaO2, and SaO2, should be regularly assessed and carefully maintained to ensure proper oxygen delivery into transplanted liver grafts.

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.

Defining Usage and Clinical Outcomes Following Perioperative Fresh Frozen Plasma and Platelet Administration in Spine Surgery Patients

STUDY DESIGN

This was a retrospective study.

OBJECTIVES

The main objectives of this study were to characterize the utilization of fresh frozen plasma (FFP) and platelets in spine surgery and the clinical outcomes following their administration.

SUMMARY OF BACKGROUND DATA

Blood component transfusion is often a crucial therapy during spine surgery. Little is known about the association between transfusion with FFP and/or platelets and perioperative morbidity in patients undergoing spine surgery.

MATERIALS AND METHODS

At a single large tertiary medical center, the surgical billing database was retrospectively queried for patients undergoing spinal surgery from 2008 to 2015. A univariate analysis compared patient characteristics for those who received FFP and/or platelets perioperatively and those who did not. To determine independent predictors of FFP and platelet administration and independent predictors of perioperative complications, both univariate and multivariate analyses were used.

RESULTS

In total, 6931 patients met inclusion criteria. One thousand seven (14.5%) patients received perioperative FFP transfusion and 432 (6.2%) received platelets. In multivariate analysis, Charlson Comorbidity Index (CCI) ≥4, preoperative hemoglobin <12 g/dL, preoperative international normalized ratio (INR) ≥1.7, higher estimated blood loss, and receipt of packed red blood cell or platelet transfusion were associated with perioperative FFP administration (all P≤0.001). More than half of all patients received FFP with an INR trigger of <1.7. Those who received perioperative FFP were more likely to experience infection, increased length of stay, and ischemic, respiratory, thrombotic, and renal complications (all P<0.0001). Perioperative FFP [odds ratio (OR): 2.43], platelet transfusion (OR: 1.81), American Society of Anesthesiologists (ASA) grade 3 or 4 (OR: 1.84), CCI≥4 (OR: 1.75), and receipt of packed red blood cells (OR: 1.73) were independent predictors of experiencing any complication (all P≤0.008).

CONCLUSIONS

The majority of patients were given FFP with a liberal INR trigger of >1.7. Perioperative FFP and platelet administration are independent predictors of perioperative complications following spine surgery.

Distinct risk factors for early and late blood transfusion following pancreaticoduodenectomy

BACKGROUND

The International Study Group of Pancreatic Surgery (ISGPS) has defined two periods of postpancreatectomy hemorrhage, early (<24 h) and late (>24 h). A previously published Blood Usage Risk Score (BURS) aimed to predict early and late blood transfusion. The primary aim of this study was to define risk factors for early and late blood transfusion after pancreaticoduodenectomy. Secondary aims were to assess the predictive accuracy of the BURS.

METHODS

In this retrospective observational study, multivariable analyses were used to identify independent risk factors for both early and late blood transfusion. The predictive ability of the BURS was then assessed using a receiver operating characteristic (ROC) curve analysis.

RESULTS

Among 628 patients, 99 (15.8%) and 144 (22.9%) received early and late blood transfusion, respectively. Risk factors for blood transfusion differed between early and late periods. Preoperative anemia and venous resection were associated with early blood transfusion whilst Whipple's resection (as opposed to pylorus preserving pancreaticoduodenectomy), lack of biliary stent and a narrow pancreatic duct were predictors of late blood transfusion. The BURS was significantly predictive of early blood transfusion, albeit with a modest degree of accuracy (AUROC: 0.700, P < 0.001), but not of late blood transfusion (AUROC: 0.525, P = 0.360). Late blood transfusion was independently associated with increasing severity of postoperative pancreatic fistula (POPF) (OR: 1.85, 3.18 and 9.97 for biochemical, types B and C POPF, respectively, relative to no POPF).

CONCLUSIONS

Two largely different sets of variables are related to early and late blood transfusion following pancreaticoduodenectomy. The BURS was significantly associated with early, albeit with modest predictive accuracy, but not late blood transfusion. An understanding of POPF risk allows assessment of the need for late blood transfusion.

Percentage change in hemoglobin level and morbidity in spine surgery patients

OBJECTIVE

The aim of this study was to characterize the association between percentage change in hemoglobin (ΔHb)—i.e., the difference between preoperative Hb and in-hospital nadir Hb concentration—and perioperative adverse events among spine surgery patients.

METHODS

Patients who underwent spine surgery at the authors’ institution between December 4, 2008, and June 26, 2015, were eligible for this retrospective study. Patients who underwent the following procedures were included: atlantoaxial fusion, subaxial anterior cervical fusion, subaxial posterior cervical fusion, anterior lumbar fusion, posterior lumbar fusion, lateral lumbar fusion, excision of intervertebral disc, and excision of spinal cord lesion. Data on intraoperative transfusion were obtained from an automated, prospectively collected, anesthesia data management system. Data on postoperative hospital transfusions were obtained through an Internet-based intelligence portal. Percentage ΔHb was defined as: ([preoperative Hb − nadir Hb]/preoperative Hb) × 100. Clinical outcomes included in-hospital morbidity and length of stay associated with percentage ΔHb.

RESULTS

A total of 3949 patients who underwent spine surgery were identified. Of these, 1204 patients (30.5%) received at least 1 unit of packed red blood cells. The median nadir Hb level was 10.6 g/dl (interquartile range 8.7–12.4 g/dl), yielding a mean percentage ΔHb of 23.6% (SD 15.4%). Perioperative complications occurred in 234 patients (5.9%) and were more common in patients with a larger percentage ΔHb (p = 0.017). Hospital-related infection, which occurred in 60 patients (1.5%), was also more common in patients with greater percentage ΔHb (p = 0.001).

CONCLUSIONS

Percentage ΔHb is independently associated with a higher risk of developing any perioperative complication and hospital-related infection. The authors’ results suggest that percentage ΔHb may be a useful measure for identifying patients at risk for adverse perioperative events.

Cerebral and Limb Tissue Oxygenation During Peripheral Venoarterial Extracorporeal Life Support

Femoral access in extracorporeal life support (ECLS) has been associated with regional variations in arterial oxygen saturation, potentially predisposing the patient to ischemic tissue damage. Current monitoring techniques, however, are limited to intermittent bedside evaluation of capillary refill among other factors. The aim of this study was to assess whether cerebral and limb regional tissue oxygen saturation (rSO₂) values reflect changes in various patient-related parameters during venoarterial ECLS (VA-ECLS). This retrospective observational study included adults assisted by femorofemoral VA-ECLS. Bifrontal cerebral and bilateral limb tissue oximetry was performed for the entire duration of support. Hemodynamic data were analyzed parallel to cerebral and limb rSO₂. A total of 23 patients were included with a median ECLS duration of 5 [1-20] days. Cardiac arrhythmias were observed in 12 patients, which was associated with a decreased mean rSO₂ from 61%±11% to 51%±10% during atrial fibrillation and 67%±9% to 58%±10% during ventricular fibrillation (P<0.001 for both). A presumably sudden increase in cardiac output due to myocardial recovery (n=8) resulted in a significant decrease in mean cerebral rSO₂ from 73%±7% to 54%±6% and from 69%±9% to 53%±8% for the left and right cerebral hemisphere, respectively (P=0.012 for both hemispheres). Also, right radial artery partial gas pressure for oxygen decreased from 15.6±2.8 to 8.3±1.9 kPa (P=0.028). No differences were found in cerebral desaturation episodes between patients with and without neurologic complications. In six patients, limb rSO₂ increased from on average 29.3±2.7 to 64.0±5.1 following insertion of a distal cannula in the femoral artery (P=0.027). Likewise, restoration of flow in a clotted distal cannula inserted in the femoral artery was necessary in four cases and resulted in increased limb rSO₂ from 31.3±0.8 to 79.5±9.0; P=0.068. Non-invasive tissue oximetry adequately reflects events influencing cerebral and limb perfusion and can aid in monitoring tissue perfusion in patients assisted by ECLS.

Transfusion Decision Making in Pediatric Critical Illness

Transfusion decision making (TDM) in the critically ill requires consideration of: (1) anemia tolerance, which is linked to active pathology and to physiologic reserve, (2) differences in donor RBC physiology from that of native RBCs, and (3) relative risk from anemia-attributable oxygen delivery failure vs hazards of transfusion, itself. Current approaches to TDM (e.g. hemoglobin thresholds) do not: (1) differentiate between patients with similar anemia, but dissimilar pathology/physiology, and (2) guide transfusion timing and amount to efficacy-based goals (other than resolution of hemoglobin thresholds). Here, we explore approaches to TDM that address the above gaps.

Effect of liberal blood transfusion on clinical outcomes and cost in spine surgery patients

BACKGROUND CONTEXT

Blood transfusions in spine surgery are shown to be associated with increased patient morbidity. The association between transfusion performed using a liberal hemoglobin (Hb) trigger-defined as an intraoperative Hb level of ≥10 g/dL, a postoperative level of ≥8 g/dL, or a whole hospital nadir between 8 and 10 g/dL-and perioperative morbidity and cost in spine surgery patients is unknown and thus was investigated in this study.

PURPOSE

This study aimed to describe the perioperative outcomes and economic cost associated with liberal Hb trigger transfusion among spine surgery patients.

STUDY DESIGN/SETTING

This is a retrospective study.

PATIENT SAMPLE

The surgical billing database at our institution was queried for inpatients discharged between 2008 and 2015 after the following procedures: atlantoaxial fusion, anterior cervical fusion, posterior cervical fusion, anterior lumbar fusion, posterior lumbar fusion, lateral lumbar fusion, other procedures, and tumor-related surgeries. In total, 6,931 patients were included for analysis.

OUTCOME MEASURES

The primary outcome was composite morbidity, which was composed of (1) infection (sepsis, surgical-site infection, Clostridium difficile infection, or drug-resistant infection); (2) thrombotic event (pulmonary embolus, deep venous thrombosis, or disseminated intravascular coagulation); (3) kidney injury; (4) respiratory event; and (5) ischemic event (transient ischemic attack, myocardial infarction, or cerebrovascular accident).

MATERIALS AND METHODS

Data on intraoperative transfusion were obtained from an automated, prospectively collected anesthesia data management system. Data on postoperative hospital transfusion were obtained through a Web-based intelligence portal. Based on previous research, we analyzed the data using three definitions of a liberal transfusion trigger in patients who underwent red blood cell transfusion: a liberal intraoperative Hb trigger as a nadir Hb level of 10 g/dL or greater, a liberal postoperative Hb trigger as a nadir Hb level of 8 g/dL or greater, or a whole hospital nadir Hb level of 8-10 g/dL. Variables analyzed included in-hospital morbidity, mortality, length of stay, and total costs associated with a liberal transfusion strategy.

RESULTS

Among patients with a whole hospital stay nadir Hb between 8 and 10 g/dL, transfused patients demonstrated a longer in-hospital stay (median [interquartile range], 6 [5-9] vs. 4 [3-6] days; p<.0001) and a higher perioperative morbidity (n=145 [11.5%] vs. n=74 [6.1%], p<.0001) than those not transfused. Even after adjusting for age, gender, race, American Society of Anesthesiologists class, Charlson Comorbidity Index score, estimated blood loss, baseline Hb value, and surgery type, logistic regression analysis revealed that patients with a nadir Hb of 8-10 g/dL who were transfused had an independently higher risk of perioperative morbidity (odds ratio=2.11, 95% confidence interval, 1.44-3.09; p<.0001). Estimated additional costs associated with liberal trigger use, defined as a transfusion occurring in patients with a whole hospital stay nadir Hb of 8-10 g/dL, ranged from $202,675 to $700,151 annually.

CONCLUSIONS

Transfusion using a liberal trigger is associated with increased morbidity, even after controlling for possible confounders. Our results suggest that modification of transfusion practice may be a potential area for improving patient outcomes and reducing costs.

Blood Transfusion Strategies in Patients Undergoing Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is frequently associated with bleeding and coagulopathy complications, which may lead to the need for transfusion of multiple blood products. However, blood transfusions are known to increase morbidity and mortality, as well as hospital cost, in critically ill patients. In current practice, patients on ECMO receive a transfusion, on average, of 1-5 packed red blood cells (RBCs)/day, with platelet transfusion accounting for the largest portion of transfusion volume. Generally, adult patients require more transfusions than neonates or children, and patients receiving venovenous ECMO for respiratory failure tend to need smaller transfusion volumes compared to those receiving venoarterial ECMO for cardiac failure. Observation studies have reported that a higher transfusion volume was associated with increased mortality. To date, the evidence for transfusion in patients undergoing ECMO is limited; most knowledge on transfusion strategies was extrapolated from studies in critically ill patients. However, current data support a restrictive blood transfusion strategy for ECMO patients, and a low transfusion trigger seems to be safe and reasonable.

Red blood cell transfusion and skeletal muscle tissue oxygenation in anaemic haematologic outpatients

Background

Stored red blood cells (RBCs) accumulate biochemical and biophysical changes, known as storage lesion. The aim of this study was to re-challenge current data that anaemia in chronically anaemic haematology patients is not associated with low skeletal muscle tissue oxygen (StO₂), and that RBC storage age does not influence the tissue response after ischaemic provocation, using near-infrared spectroscopy.

Patients and methods

Twenty-four chronic anaemic haematology patients were included. Thenar skeletal muscle StO₂ was measured at rest (basal StO₂), with vascular occlusion testing (upslope StO₂, maximum StO₂) before and after transfusion.

Results

Basal StO₂ was low (53% ± 7%). Average RBC storage time was 10.5 ± 3.9 days. Effects of RBC transfusions were as follows: basal StO₂ and upslope StO₂ did not change significantly; maximum StO₂ increased compared to baseline (64 ± 14% vs. 59 ± 10%, p = 0.049). Change of basal StO₂, upslope StO₂ and maximum StO₂ was negatively related to age of RBCs. The decrease of maximum StO₂ was predicted (sensitivity 70%, specificity 100%), after receiving RBCs ≥ 10days old.

Discussion

Resting skeletal muscle StO₂ in chronic anaemic patients is low. RBC storage time affects skeletal muscle StO₂ in the resting period and after ischaemic provocation.

Nomogram to predict perioperative blood transfusion for hepatopancreaticobiliary and colorectal surgery

Background

Predictive tools assessing risk of transfusion have not been evaluated extensively among patients undergoing complex gastrointestinal surgery. In this study preoperative variables associated with blood transfusion were incorporated into a nomogram to predict transfusion following hepatopancreaticobiliary (HPB) or colorectal surgery.

Methods

A nomogram to predict receipt of perioperative transfusion was developed using a cohort of patients who underwent HPB or colorectal surgery between January 2009 and December 2014. The discriminatory ability of the nomogram was tested using the area under the receiver operating characteristic (ROC) curve and internal validation performed via bootstrap resampling.

Results

Among 4961 patients undergoing either a HPB (56·3 per cent) or colorectal (43·7 per cent) resection, a total of 1549 received at least 1 unit of packed red blood cells, giving a perioperative transfusion rate of 31·2 per cent. On multivariable analysis, age 65 years and over (odds ratio (OR) 1·52), race (versus white: black, OR 1·58; Asian, OR 1·86), preoperative haemoglobin 8·0 g/dl or less (versus over 12·0 g/dl: OR 26·79), preoperative international normalized ratio more than 1·2 (OR 2·44), Charlson co-morbidity index score over 3 (OR 1·86) and procedure type (versus colonic surgery: major hepatectomy, OR 1·71; other pancreatectomy, OR 2·12; rectal surgery, OR 1·39; duodenopancreatectomy, OR 2·65) were associated with a significantly higher risk of transfusion and were included in the nomogram. A nomogram was constructed to predict transfusion using these seven variables. Discrimination and calibration of the nomogram revealed good predictive abilities (area under ROC curve 0·756).

Conclusion

The nomogram predicted blood transfusion in major HPB and colorectal surgery.

Impact of Transfusion on Cancer Growth and Outcome

For many years, transfusion of allogeneic red blood cells, platelet concentrates, and plasma units has been part of the standard therapeutic arsenal used along the surgical and nonsurgical treatment of patients with malignancies. Although the benefits of these blood products are not a matter of debate in specific pathological conditions associated with life-threatening low blood cell counts or bleeding, increasing clinical evidence is nevertheless suggesting that deliberate transfusion of these blood components may actually lead to negative clinical outcomes by affecting patient’s immune defense, stimulating tumor growth, tethering, and dissemination. Rigorous preclinical and clinical studies are needed to dimension the clinical relevance, benefits, and risks of transfusion of blood components in cancer patients and understand the amplitude of problems. There is also a need to consider validating preparation methods of blood components for so far ignored biological markers, such as microparticles and biological response modifiers. Meanwhile, blood component transfusions should be regarded as a personalized medicine, taking into careful consideration the status and specificities of the patient, rather than as a routine hospital procedure.

Red Cell Transfusion Triggers and Postoperative Outcomes After Major Surgery

BACKGROUND

The effect of packed red blood cell (PRBC) transfusion on postoperative outcomes of patients undergoing major surgery remains unclear. We sought to determine the impact of blood utilization, as well as transfusion practices, on perioperative outcomes of patients undergoing cardiothoracic-vascular (CT-V) and gastrointestinal (GI) procedures.

METHODS

Patients who underwent major surgical procedures at Johns Hopkins Hospital between 2009 and 2014 were identified. Data on perioperative hemoglobin (Hb) and blood utilization were obtained; transfusion strategy was categorized as liberal (Hb trigger ≥7 g/dL) vs. restrictive (Hb trigger <7 g/dL). Risk-adjusted logistic regression models and propensity score matching were used to assess the association between transfusion triggers and perioperative morbidity.

RESULTS

Among 10,163 patients undergoing either CT-V (50.9 %) or GI (49.1 %) surgery, 4401 (43.3 %) patients received PRBCs. Of the 4401 patients transfused, 71.2 % were transfused using a liberal trigger (≥7 g/dL hemoglobin), while 28.8 % had a restrictive trigger (<7 g/dL). The median number of PRBCs transfused was 3 (restrictive 5 vs. liberal 2 units). While ischemic adverse events were more common among patients undergoing CT-V surgery (17.3 %), infection was the more common complication among patients undergoing GI surgery (11.9 %). American Society of Anesthesiologist (ASA) class 3-4, Charlson score ≥3, and total units of transfused PRBCs were independently associated with overall complications (all P < 0.05). Patients in the restrictive transfusion group did not have increased risk of complications compared with the liberal transfusion group on multivariable analysis (odds ratio (OR) 1.16, 95 % confidence interval (CI) 0.98-1.38; P = 0.08) or after propensity score matching (OR 1.04, 95 % CI 0.88-1.22; P = 0.65).

CONCLUSIONS

Liberal transfusion triggers after major surgery were more common than restrictive practice. Patients with restrictive transfusion trigger did not have increased risk for complications compared with patients transfused with a liberal trigger.

Clinical Outcomes Associated With RBC Transfusions in Critically Ill Children: A 1-Year Prospective Study

OBJECTIVE

To identify the potential complications associated with RBC transfusions.

DESIGN

Prospective observational study.

SETTING

PICU in a tertiary children's hospital.

PATIENTS

All children consecutively admitted to our PICU during a 1-year period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data were abstracted from medical charts prospectively. Outcomes possibly attributable to RBC transfusions were looked for daily. In transfused cases, it was considered that an outcome was associated with a transfusion only if it was observed after the first RBC transfusion. During the 1-year study period, 913 consecutive admissions were documented, 842 of which were included. Among them, 144 (17%) were transfused at least once. When comparing transfused cases with nontransfused cases, the odds ratio for new or progressive multiple organ dysfunction syndrome was 5.14 (95% CI, 3.28-8.06; p < 0.001). This association remained statistically significant in the multivariable analysis (odds ratio, 3.85; 95% CI, 2.38-6.24; p < 0.001). Transfused cases were ventilated longer than nontransfused cases (14.1 ± 32.6 vs 4.3 ± 9.6 d, p < 0.001), even after adjustment in a Cox model. The PICU length of stay was significantly increased for transfused cases (12.4 ± 26.2 vs 4.9 ± 10.2 d, p < 0.001), even after controlling for potential confounders. The paired analysis for comparison of pretransfusion and posttransfusion values showed that the arterial partial pressure in oxygen was significantly reduced within the 6 hours after the first RBC transfusion (mean difference, 25.6 torr, 95% CI, 5.7-45.4; p = 0.029). The paired analysis also showed an increased proportion of renal replacement therapy.

CONCLUSIONS

RBC transfusions in critically ill children were associated with prolonged mechanical ventilation and prolonged PICU stay. The risk of new or progressive multiple organ dysfunction syndrome was also increased in some transfused children. Furthermore, our study questions the ability of stored RBCs to improve oxygenation in critically ill children. Practitioners should take into account these data when prescribing an RBC transfusion to PICU patients.

Transcutaneous oxygen tension monitoring in critically ill patients receiving packed red blood cells

PURPOSE

Whether transfusions of packed red blood cells (PRBCs) affect tissue oxygenation in stable critically ill patients is still matter of discussion. The microvascular capacity for tissue oxygenation can be determined noninvasively by measuring transcutaneous oxygen tension (tcpO2). The aim of this study was to assess tissue oxygenation by measuring tcpO2 in stable critically ill patients receiving PRBC transfusions.

METHODS

Nineteen stable critically ill patients, who received 2 units of PRBC, were prospectively included into this pilot study. Transcutaneous oxygen tension was measured continuously during PRBC transfusions using Clark's electrodes. In addition, whole blood viscosity and global hemodynamics were determined.

RESULTS

Reliable measurement signals during continuous tcpO2 monitoring were observed in 17 of 19 included patients. Transcutaneous oxygen tension was related to the global oxygen consumption (r=-0.78; P=.003), the arterio-venous oxygen content difference (r=-0.65; P=.005), and the extraction rate (r=-0.71; P=.02). The transfusion-induced increase of the hemoglobin concentration was paralleled by an increase of the whole blood viscosity (P<.001). Microvascular tissue oxygenation by means of tcpO2 was not affected by PRBC transfusions (P=.46). Packed red blood cell transfusions resulted in an increase of global oxygen delivery (P=.02) and central venous oxygen saturation (P=.01), whereas oxygen consumption remained unchanged (P=.72).

CONCLUSIONS

In stable critically ill patients, microvascular tissue oxygenation can be continuously monitored by Clark's tcpO2 electrodes. According to continuous tcpO2 measurements, the microvascular tissue oxygenation is not affected by PRBC transfusions.

Quantitative Systems Pharmacology Model of NO Metabolome and Methemoglobin Following Long-Term Infusion of Sodium Nitrite in Humans

A long-term sodium nitrite infusion is intended for the treatment of vascular disorders. Phase I data demonstrated a significant nonlinear dose-exposure-toxicity relationship within the therapeutic dosage range. This study aims to develop a quantitative systems pharmacology model characterizing nitric oxide (NO) metabolome and methemoglobin after sodium nitrite infusion. Nitrite, nitrate, and methemoglobin concentration–time profiles in plasma and RBC were used for model development. Following intravenous sodium nitrite administration, nitrite undergoes conversion in RBC and tissue. Nitrite sequestered by RBC interacts more extensively with deoxyhemoglobin, which contributes greatly to methemoglobin formation. Methemoglobin is formed less-than-proportionally at higher nitrite doses as characterized with facilitated methemoglobin removal. Nitrate-to-nitrite reduction occurs in tissue and via entero-salivary recirculation. The less-than-proportional increase in nitrite and nitrate exposure at higher nitrite doses is modeled with a dose-dependent increase in clearance. The model provides direct insight into NO metabolome disposition and is valuable for nitrite dosing selection in clinical trials.