Effect of Red Blood Cell Transfusion on Unfavorable Neurologic Outcome and Symptomatic Vasospasm in Patients with Cerebral Aneurysmal Rupture: Old versus Fresh Blood

Anemia and Optimal Transfusion Thresholds in Brain-Injured Patients: A Narrative Review of the Literature

Anemia is a highly prevalent condition that may compromise oxygen delivery to vital organs, especially among the critically ill. Although current evidence supports the adoption of a restrictive transfusion strategy and threshold among the nonbleeding critically ill patient, it remains unclear whether this practice should apply to the brain-injured patient, given the predisposition to cerebral ischemia in this patient population, in which even nonprofound anemia may exert a detrimental effect on clinical outcomes. The purpose of this review is to provide an overview of the pathophysiological changes related to impaired cerebral oxygenation in the brain-injured patient and to present the available evidence on the effect of anemia and varying transfusion thresholds on the clinical outcomes of patients with acute brain injury.

Effect of Peri-operative Blood Transfusion on Neurological Outcome Following Aneurysmal Subarachnoid Hemorrhage: A Prospective Observational Study

BACKGROUND

Anemia is a common complication of aneurysmal subarachnoid hemorrhage and is associated with unfavorable outcomes. Whether the physiological benefits of transfusion for anemia surpass the risk of blood transfusion remains to be determined.

OBJECTIVES

The primary outcome was to evaluate the impact of peri-operative blood transfusion on the long-term neurological outcome, assessed by Glasgow Outcome Scale Extended at 3 months. The secondary outcomes included the impact of transfusion on the short-term neurological outcome, assessed by Modified Rankin Score at discharge/7 days, and on the incidence of vasospasm, infarction, re-exploration, tracheostomy, and length of hospital stay.

MATERIAL AND METHODS

This prospective observational study was conducted on 185 patients with aneurysmal subarachnoid hemorrhage undergoing clipping of the aneurysmal neck. In our study, blood transfusion was administered to keep the target Hb around 10 g/dL.

RESULTS

Unfavorable long-term outcome was found in 27/97 (28%) of patients who received a blood transfusion as compared to 13/74 (18%) of patients who did not receive a transfusion (P = 0.116). Patients receiving transfusion had more chances of an unfavorable outcome at discharge/7 days as compared to those not transfused [44/103 (43%) versus 22/80 (27%)], P = 0.025. There were increased chances of vasospasm, infarction, re-exploration, tracheostomy, and increased length of hospital stay in patients receiving transfusion (P < 0.05).

CONCLUSIONS

The use of blood transfusion in patients with aneurysmal subarachnoid hemorrhage was associated with increased neurological complications and hence an unfavorable short-term outcome. However, when used judiciously as per the clinical requirements, blood transfusion did not have a significant effect on long-term neurological outcome.

Systematic review and meta-analysis of outcome-relevant anemia in patients with subarachnoid hemorrhage

Anemia is a common, treatable condition in patients with aneurysmal subarachnoid hemorrhage (SAH) and has been associated with poor outcome. As there are still no guidelines for anemia management after aneurysm rupture, we aimed to identify outcome-relevant severity of anemia in SAH. We systematically searched PubMed, Embase, Scopus, Web of Science, and Cochrane Library for publications before Oct 23rd, 2022, reporting on anemia in SAH patients. The presence and severity of anemia were assessed according to the reported hemoglobin values and/or institutional thresholds for red blood cells transfusion (RBCT). Out of 1863 original records, 40 full-text articles with a total of 14,701 patients treated between 1996 and 2020 were included in the final analysis (mean 445.48 patients per study). A substantial portion of patients developed anemia during SAH (mean pooled prevalence 40.76%, range 28.3-82.6%). RBCT was administered in a third of the cases (mean 32.07%, range 7.8-88.6%), with institutional threshold varying from 7.00 to 10.00 g/dL (mean 8.5 g/dL). Anemia at the onset of SAH showed no impact on SAH outcome. In contrast, even slight anemia (nadir hemoglobin < 11.0-11.5 g/dL) occurring during SAH was associated with the risk of cerebral infarction and poor outcome at discharge and follow-up. The strongest association with SAH outcome was observed for nadir hemoglobin values ranging between 9.0 and 10.0 g/dL. The effect of anemia on SAH mortality was marginal. The development of anemia during SAH is associated with the risk of cerebral infarction and poor outcome at discharge and follow-up. Outcome-relevant severity of post-SAH anemia begins at hemoglobin levels clearly above the thresholds commonly set for RBCT. Our findings underline the need for further studies to define the optimal management of anemia in SAH patients.

Impact of Anemia Severity on the Outcome of an Aneurysmal Subarachnoid Hemorrhage

Objective: Previous reports indicate a negative impact of anemia on the outcome of an aneurysmal subarachnoid hemorrhage (SAH). We aimed to identify the outcome-relevant severity of post-SAH anemia. Methods: SAH cases treated at our institution between 01/2005 and 06/2016 were included (n = 640). The onset, duration, and severity (nadir hemoglobin (nHB) level) of anemia during the initial hospital stay were recorded. Study endpoints were new cerebral infarctions, a poor outcome six months post-SAH (modified Rankin scale > 3), and in-hospital mortality. To assess independent associations with the study endpoints, different multivariable regression models were performed, adjusted for relevant patient and baseline SAH characteristics as well as anemia-associated clinical events during the SAH. Results: The rates of anemia were 83.3%, 67.7%, 40.0%, 15.9%, and 4.5% for an nHB < 11 g/dL, < 10 g/dL, < 9 g/dL, < 8 g/dL, and < 7 g/dL, respectively. The higher the anemia severity, the later was the onset (post-SAH days 2, 4, 5.4, 7.6 and 8, p < 0.0001) and the shorter the duration (8 days, 6 days, 4 days, 3 days, and 2 days, p < 0.0001) of anemia. In the final multivariable analysis, only an nHB < 9 g/dL was independently associated with all study endpoints: adjusted odds ratio 1.7/3.22/2.44 for cerebral infarctions/in-hospital mortality/poor outcome. The timing (post-SAH day 3.9 vs. 6, p = 0.001) and duration (3 vs. 5 days, p = 0.041) of anemia with an nHB < 9 g/dL showed inverse associations with the risk of in-hospital mortality, but not with other study endpoints. Conclusions: Anemia is very common in SAH patients affecting four of five individuals during their hospital stay. An nHB decline to < 9 g/dL was strongly associated with all study endpoints, independent of baseline characteristics and SAH-related clinical events. Our data encourage further prospective evaluations of the value of different transfusion strategies in the functional outcomes of SAH patients.

Postoperative Transfusion Guidelines in Aneurysmal Cerebral Subarachnoid Hemorrhage: A Systematic Review and Critical Summary of Available Evidence

OBJECTIVE

Surgical management of aneurysmal subarachnoid hemorrhage (SAH) often involves red blood cell (RBC) transfusion, which increases the risk of postoperative complications. RBC transfusion guidelines report on chronically critically ill patients and may not apply to patients with SAH. Our study aims to synthesize the evidence to recommend RBC transfusion thresholds among adult patients with SAH undergoing surgery.

METHODS

A systematic review was conducted using PubMed, Google Scholar, and Web of Science electronic databases according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to critically assess primary articles discussing RBC transfusion thresholds and describe complications secondary to RBC transfusion in adult patients with SAH in the perioperative period.

RESULTS

Sixteen articles meeting our search strategy were reviewed. Patients with SAH who received blood transfusion were older, female, had World Federation of Neurosurgical Societies grade IV-V and modified Fisher grade 3-4 scores, and presented with more comorbidities such as hypertension, diabetes, and cardiovascular and pulmonary diseases. In addition, transfusion was associated with multiple postoperative complications, including higher rates of vasospasms, surgical site infections, cardiovascular and respiratory complications, increased postoperative length of stay, and 30-day mortality. Analysis of transfused patients showed that a higher hemoglobin (>10 g/dL) goal after SAH was safe and that patients may benefit from a higher whole hospital stay hemoglobin nadir, as shown by a reduction in risk of cerebral vasospasm and improvement in clinical outcomes (level B class II).

CONCLUSIONS

Among patients with SAH, the benefits of reducing cerebral ischemia and anemia are shown to outweigh the risks of transfusion-related complications.

Association of anemia and transfusions with outcome after subarachnoid hemorrhage

INTRODUCTION

The benefits of correcting anemia using red blood cell transfusion (RBCT) after subarachnoid hemorrhage (SAH) are controversial. We aimed to evaluate the role of anemia and RBCT on neurological outcome after SAH using a restrictive transfusion policy.

OBJECTIVE

We reviewed our institutional database of adult patients admitted to the Department of Intensive Care (ICU) after non-traumatic SAH over a 5-year period. We recorded hemoglobin (Hb) levels daily for a maximum of 20 days, as well as the use of RBCT. Unfavorable neurological outcome (UO) was defined as a Glasgow Outcome Score of 1-3 at 3 months.

RESULTS

Among 270 eligible patients, UO was observed in 40% of them. Patients with UO had lower Hb over time and received RBCT more frequently than others (15/109, 14% vs. 6/161, 4% - p < 0.01). Pre-RBCT median Hb values were similar in UO and FO patients (6.9 [6.6-7.1] vs. 7.3 [6.3-8.1] g/dL - p = 0.21). The optimal discriminative Hb threshold for UO was 9 g/dL. In a multivariable analysis, neither anemia nor RBCT were independently associated with UO.

CONCLUSION

In this retrospective single center study using a restrictive strategy of RBCT in SAH patients was not associated with worse outcome in 3 months.

Hemodynamic Functionality of Transfused Red Blood Cells in the Microcirculation of Blood Recipients

The primary goal of red blood cell (RBC) transfusion is to supply oxygen to tissues and organs. However, due to a growing number of studies that have reported negative transfusion outcomes, including reduced blood perfusion, there is rising concern about the risks in blood transfusion. RBC are characterized by unique flow-affecting properties, specifically adherence to blood vessel wall endothelium, cell deformability, and self-aggregability, which define their hemodynamic functionality (HF), namely their potential to affect blood circulation. The role of the HF of RBC in blood circulation, particularly the microcirculation, has been documented in numerous studies with animal models. These studies indicate that the HF of transfused RBC (TRBC) plays an important role in the transfusion outcome. However, studies with animal models must be interpreted with reservations, as animal physiology may not reflect human physiology. To test this concept in humans, we have directly examined the effect of the HF of TRBC, as expressed by their deformability and adherence to vascular endothelium, on the transfusion-induced effect on the skin blood flow and hemoglobin increment in β-thalassemia major patients. The results demonstrated, for the first time in humans, that the TRBC HF is a potent effector of the transfusion outcome, expressed by the transfusion-induced increase in the recipients' hemoglobin level, and the change in the skin blood flow, indicating a link between the microcirculation and the survival of TRBC in the recipients' vascular system. The implication of these findings for blood transfusion practice and to vascular function in blood recipients is discussed.

Red blood cell storage time and transfusion: current practice, concerns and future perspectives

Red blood cells (RBCs) units are the most requested transfusion product worldwide. Indications for transfusion include symptomatic anaemia, acute sickle cell crisis, and acute blood loss of more than 30% of the blood volume, with the aim of restoring tissue oxygen delivery. However, stored RBCs from donors are not a qualitative equal product, and, in many ways, this is a matter of concern in the transfusion practice. Besides donor-to-donor variation, the storage time influences the RBC unit at the qualitative level, as RBCs age in the storage bag and are exposed to the so-called storage lesion. Several studies have shown that the storage lesion leads to post-transfusion enhanced clearance, plasma transferrin saturation, nitric oxide scavenging and/or immunomodulation with potential unwanted transfusion-related clinical outcomes, such as acute lung injury or higher mortality rate. While, to date, several studies have claimed the risk or deleterious effects of "old" vs "young" RBC transfusion regimes, it is still a matter of debate, and consideration should be taken of the clinical context. Transfusion-dependent patients may benefit from transfusion with "young" RBC units, as it assures longer inter-transfusion periods, while transfusion with "old" RBC units is not itself harmful. Unbiased Omics approaches are being applied to the characterisation of RBC through storage, to better understand the (patho)physiological role of microparticles (MPs) that are found naturally, and also on stored RBC units. Perhaps RBC storage time is not an accurate surrogate for RBC quality and there is a need to establish which parameters do indeed reflect optimal efficacy and safety. A better Omics characterisation of components of "young" and "old" RBC units, including MPs, donor and recipient, might lead to the development of new therapies, including the use of engineered RBCs or MPs as cell-based drug delivering tools, or cost-effective personalised transfusion strategies.

Effects of simvastatin and taurine on delayed cerebral vasospasm following subarachnoid hemorrhage in rabbits

The aim of the current study was to observe the effects of simvastatin and taurine on delayed cerebral vasospasm (DCVS) following experimental subarachnoid hemorrhage (SAH) in rabbits. A total of 48 New Zealand white rabbits were allocated at random into four groups (control, SAH, SAH + simvastatin and SAH + taurine groups; n=12 each). The rabbit model of DCVS was established using a double hemorrhage method, which involved injecting autologous arterial blood into the cisterna magna in the SAH groups. The SAH + simvastatin group was administered oral simvastatin (5 mg/kg) daily between days 0-6. The SAH + taurine group was administered oral taurine (50 mg/kg) daily between days 0-6. Starch (50 mg/kg) was administered orally to the animals in the other two groups (control and SAH groups). The control group were not subjected to any other injections or treatment. The internal diameter and internal diameter/wall thickness of the basilar artery (BA) were measured. The expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were determined using immunohistochemical and quantitative polymerase chain reaction methods following the sacrifice of all animals on day 7. The activity of nuclear factor (NF)-κB in the BA was also measured using an electrophoretic mobility shift assay. The BA walls in the SAH + simvastatin and SAH + taurine groups exhibited reduced narrowing and corrugation of the tunica elastica interna compared with the SAH group. At the protein and cDNA levels, it was found that cerebral vasospasm of the BA in the SAH + simvastatin and SAH + taurine groups was alleviated, as indicated by the reduced expression of TNF-α, IL-1β, IL-6 and NF-κB compared with the SAH group (P<0.05). In conclusion, simvastatin and taurine reduced DCVS following SAH in rabbits, which suggests that these compounds may exert anti-inflammatory effects.