Acute Normovolemic Hemodilution Is Safe in Neurosurgery

Effectiveness, safety and indications of acute normovolemic haemodilution in total knee arthroplasty

Total knee arthroplasty (TKA) is the most cost-effective, and potent method for the treatment of end-stage knee osteoarthritis. Acute normovolemic haemodilution (ANH) can effectively replace the need for allogeneic transfusions due to the high amount of bleeding during TKA. However, more studies are needed to prove the efficacy and safety of ANH and to clarify its indications in the field of knee replacement. Medical records from June 1, 2019 to June 1, 2021 were searched and grouped according to inclusion and exclusion criteria.

PART I

58 patients with ANH during TKA were selected as the ANH group (n = 58), and 58 patients with allogeneic transfusion were chosen as the control group (n = 58).

PART II

Patients with anaemia were divided into the ANH group (n = 18) and the control group (n = 12).

PART I

The postoperative inflammatory index and serum albumin in the ANH group were significantly lower than those in the control group. No significant difference was observed in the theoretical loss of red blood cells, postoperative renal function, liver function, cardiac function and biochemical ion index between the two groups. The effective rate of ANH in the normal haemoglobin group was significantly lower than that in the anaemia group.

PART II

In patients with anaemia, the theoretical loss of red blood cells in patients with ANH was less than that in the control group. The postoperative inflammation, renal function, liver function and cardiac function in the ANH group were better than those in the control group, and no significant difference was noted in biochemical ions and nutritional status indicators. This paper shows that ANH not only can replace allogeneic transfusion in TKA, especially in patients with anaemia, but also has lower inflammatory indicators than allogeneic transfusion. From a security perspective, the body's tolerance to ANH is within the body's compensation range.

The role of acute normovolemic hemodilution in reducing allogeneic blood transfusion in glioblastoma surgery: a case-control study

BACKGROUND

Acute normovolemic hemodilution (ANH) was first introduced in glioblastoma surgery, and its role in reducing allogeneic blood transfusion was investigated in this study.

METHODS

This study enrolled supratentorial glioblastoma patients who received total resection. In the ANH group, the patients were required to draw blood before the operation, and the blood will be transfused back to the patient during the operation. The association between ANH and clinical features was investigated.

RESULTS

Sixty supratentorial glioblastoma patients were enrolled in this study, 25 patients were allocated in the ANH group, and another 35 patients were included in the control group. ANH dramatically reduced the need for allogeneic blood transfusion (3 [12%] vs 12 [34.3%], P = 0.049), and the blood transfusion per total of patients was dramatically decreased by the application of ANH (0.40 ± 1.15 units vs 1.06 ± 1.59 units, P = 0.069). Furthermore, ANH also markedly reduced the requirement of fresh frozen plasma (FFP) transfusion (2 [8%] vs 11 [31.4%], P = 0.030) and the volume of FFP transfusion per total of patients (32.00 ± 114.46 mL vs 115.71 ± 181.00 mL, P = 0.033). The complication rate was similar between the two groups.

CONCLUSIONS

ANH was a safe and effective blood conservation technique in glioblastoma surgery.

Autologous versus allogeneic blood transfusion: A comparative study of the peri-operative outcomes in a tertiary care hospital in South India amidst the COVID-19 pandemic

Autologous blood transfusion is known to have advantages over allogeneic transfusion. The COVID-19 pandemic intensified the already existing shortage of allogeneic blood supply. We carried out a study during this period with the aim to elicit the effects of autologous blood collection and transfusion, to compare the peri-operative outcomes of autologous and allogeneic transfusion practices and also to assess the influence of the autologous transfusion programme in the Blood Centre inventory. It was prospective observational comparative study among neurosurgical and vascular surgical patients in a tertiary care centre in South India. 141 patients were allocated into Group I (n = 71) who received autologous transfusion and those who received conventional allogeneic transfusion were clustered as Group II (n = 72) for analysis. We employed Acute Normovolemic Hemodilution (ANH), Pre-deposit Autologous Donation (PAD) and Intra-operative Cell Salvage (ICS) as various modalities for autologous blood collection. In our study, 43 (60.6%) from Group I received exclusive autologous blood transfusion, whereas 28 (39.4%) required additional allogeneic transfusion. No significant difference in hemoglobin, hematocrit, platelet count and INR were observed between the groups post transfusion. Significant difference was observed in the thoracoabdominal aortic aneurysm (TAAA) patients with respect to duration of ICU stay (2.7 ± 1.1 days in Group I and 6.2 ± 0.8 days in Group II; p = 0.002) and re-exploration due to bleeding (16.7% in Group I and 40% in Group II; p = 0.048). Autologous blood transfusion is safe and effective. It can be employed as routine practice and also during any acute shortage or pandemic.

Patient Blood Management programs for post-partum hemorrhage

Patient blood management (PBM) strategies aim to maintain hemoglobin concentration, optimize hemostasis, and minimize blood loss to improve patient outcomes. Because postpartum hemorrhage (PPH) is a leading cause of maternal mortality and blood product utilization, PBM principles can be applied in its therapeutic approach. First, pre-operative identification of risk factors for PPH and identification of peri-delivery anemia should be conducted. Iron supplementation should be used to optimize hemoglobin concentration before delivery; it can also be used to treat anemia in the postpartum period after severe PPH. Both acute normovolemic hemodilution and intraoperative cell salvage can be effective techniques to reduce allogeneic blood transfusion during or after surgical procedures. Furthermore, these strategies appear to be safe when used in the pregnant population.

Comparison of Different Blood Transfusion Methods in Patients Undergoing Cesarean Section

Purpose

To compare the effect of allogeneic transfusion and acute normovolemic hemodilution (ANH) autologous transfusion in patients undergoing cesarean section.

Methods

Patients who underwent cesarean section and received blood transfusion therapy from February 2019 to July 2021 in our hospital were observed and divided into the allogeneic group (n = 55) who received allogeneic transfusion therapy and the autologous group (n = 55) who received ANH autologous transfusion therapy according to the mode of transfusion. Observations included vital signs [heart rate (HR), mean arterial pressure (MAP), stroke volume variation (SVV)], blood routine [red blood cells (RBC), platelets (PLT), hematocrit (HCT), hemoglobin (Hb)], T-cell subsets (CD4⁺, CD8⁺, CD4⁺/CD8⁺), immunoglobulins (IgA, IgM, IgG), inflammatory factors [C-reactive protein (CRP), tumor necrosis factor (TNF)-α, interleukin (IL)-6], and adverse effects were counted in both groups.

Results

There was no statistical significance in the intra-group and inter-group comparisons of HR, MAP, and SVV between the two groups before transfusion and transfusion for 10 min (P > 0.05). 5d after operation, the RBC, PLT, HCT, and Hb of the allogeneic group were lower than those before operation, and the autologous group was higher than that of the allogeneic group (P < 0.05). 5d after operation, the CRP, TNF-α, and IL-6 of the allogeneic group were higher than those before operation, and the autologous group was lower than that of the allogeneic group (P < 0.05). 5d after operation, the CD4⁺, CD4⁺/CD8⁺ of the allogeneic group were lower than before operation, and the CD8⁺ was higher than before operation. The CD4⁺ and CD4⁺/CD8⁺ of the autologous group were higher than that of the allogeneic group, and CD8⁺ was lower than that of the allogeneic group (P < 0.05). 5d after operation, the IgA, IgG, and IgM of the allogeneic group were lower than those before operation, and the autologous group was higher than that of the allogeneic group (P < 0.05). During blood transfusion, there was no significant difference in the adverse reaction rate between the two groups (P > 0.05).

Conclusion

Both allogeneic transfusion and ANH autologous transfusion have little effect on the vital signs of patients undergoing cesarean section, but ANH autologous transfusion is more helpful to the stability of blood routine, T-cell subsets, immunoglobulin, and inflammation levels after surgery, which is a safe and effective way of blood transfusion.

Acute normovolemic hemodilution in combination with tranexamic acid is an effective strategy for blood management in lumbar spinal fusion surgery

Background

The retrospective study was designed to compare the effectiveness and safety of acute normovolemic hemodilution (ANH), tranexamic Acid (TXA), and a combination of ANH and TXA in lumbar spinal fusion surgery.

Methods

Data of 120 patients underwent multi-level posterior spinal fusion for treating degenerative lumbar disease between June 2013 and December 2017 was collected, retrospectively. Four treatment strategies were enrolled, including ANH, TXA, a combination of ANH and TXA, and without any patient blood management. Intraoperative blood loss, hemoglobin and PCV at the end of surgery and at the postoperative first day, and postoperative drain collection, and intraoperative and postoperative transfusion and rate of transfusion were also collected.

Results

Intraoperative blood loss and postoperative drain collection of the TXA group, ANH combined with TXA group were statistically lower than those in the control group and ANH group (P < 0.05). Intraoperative and postoperative transfusion amount and rate of intra-operative allogenic transfusion of the ANH group, TXA group, and ANH combined with TXA group were statistically lower than those of the control group (P < 0.05). Hemoglobin and PCV at postoperative the first day in the ANH group, TXA group, and ANH combined with TXA group were significant higher than those in the control group (P < 0.05). The combination of TXA and ANH group achieved the lowest intraoperative blood loss, postoperative drain collection and allogenic transfusion rate.

Conclusion

A combination of TXA and ANH might be an effective strategy for reducing the rate of transfusion and blood loss in patients underwent lumbar spinal fusion surgery.

Blood preservation techniques in complex spine surgery: Illustrative case and review of therapeutic options

Background:

Complex spine surgery predisposes patients to substantial levels of blood loss, which can increase the risk of surgical morbidity and mortality.

Case Description:

A 29-year-old achondroplastic male required thoracolumbar deformity correction. However, he refused potential allogeneic blood transfusions for religious reasons. He, therefore, underwent pre-operative autologous blood donation and consented to the use of the intraoperative cell salvage device. Immediately prior to the incision, he underwent acute normovolemic hemodilution. Throughout the case, we additionally utilized meticulous hemostasis. Postoperatively, he was supplemented with iron and erythropoietin and recovered well. When he required a revision procedure 3 months later, similar strategies were successfully employed.

Conclusion:

Numerous strategies exist pre-operatively, intraoperatively, and post-operatively to optimize blood loss management for patients who refuse blood transfusions but warrant major spinal deformity surgery.

Effect of continuous infusion of dexmedetomidine on blood loss in orthognathic surgery: a retrospective study

BACKGROUND

Patients with maxillofacial deformities require orthognathic surgeries to correct occlusion. The surgical procedure may lead to massive bleeding, which is associated with haematoma, respiratory obstruction, and asphyxia. Dexmedetomidine has been used in controlled hypotension and may reduce blood loss in orthognathic surgery. We conducted a retrospective cohort study to evaluate the effect of dexmedetomidine on blood loss in orthognathic surgeries.

METHODS

The primary outcome examined was blood loss, and secondary outcomes were postoperative haemoglobin level; intraoperative heart rate and blood pressure (T1: at incision; T2: 30 min after incision; T3: 60 min after incision; T4: 120 min after incision); dosage of fentanyl, remifentanil, urapidil, and esmolol; operation time; and incidence of allogeneic blood transfusion.

RESULTS

A total of 1247 patients were included in this study, and 540 patient pairs were matched via propensity score matching. There were significant decreases in mean blood loss, heart rate at T1-T4, blood pressure at T1, and remifentanil and esmolol dosage in the dexmedetomidine group compared with those in the control group. There was also a significant increase in the postoperative haemoglobin level of the dexmedetomidine group.

CONCLUSIONS

Continuous infusion of dexmedetomidine can decrease blood loss in orthognathic surgery.

TRIAL REGISTRATION

ChiCTR1800018794 (retrospectively registered) Name of registry: Chinese Clinical Trial Registry Date of registration: 2018/10/09 URL: www.chictr.org.cn/showproj.aspx?proj=30612.

Calvarial Lesions: A Tertiary Centre's Experience Over Fifteen Years

Background

The human calvaria harbors a variety of pathology and majority of them are incidentally noticed as painless swelling. The aim of the present study is to describe the histopathological subtypes of calvarial lesions, their management and factors affecting their surgical outcome at a tertiary care referral center.

Material and Methods

All patients who underwent excision of the calvarial lesions over the last 15 years (from January 2005 to July 2019) were included in this study. Patients having calvarial pathology of infective origin and recurrent lesions were excluded. Any patient with multiple calvarial lesions who have been operated more than one time for same histopathological diagnosis was counted as one patient. We studied Karnofsky Performance Status (KPS) scores and radiological changes at 3-month follow up.

Results

Total 65 patients were recruited in this retrospective observational study. The median age of patients in the study was 29 years (range: 8 years to 68 years). Fibrous dysplasia 20 (30.7%) was the commonest lesion while metastatic thyroid carcinoma 3 (4.6%) was the most common malignant pathology. Complete excision was performed in 51 (78.5%) of patients while in 14 (21.5%) cases, subtotal or near total decompression were achieved. After three months of surgery, there was significant improvement in the KPS score (P < 0.00001). Duration of follow up ranges from 6 months to 5 years with 4 mortality in the study.

Conclusions

Most of the calvarial tumors were benign and surgically addressable. The malignant lesions were scattered with diverse underlying pathology and required individualized holistic approach.

The Use of Acute Normovolemic Hemodilution in Clipping Surgery for Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

The occurrence of coronavirus disease 2019 (COVID-19) has overwhelmed the blood supply chain worldwide and severely influenced clinical procedures with potential massive blood loss, such as clipping surgery for aneurysmal subarachnoid hemorrhage (aSAH). Whether acute normovolemic hemodilution (ANH) is safe and effective in aneurysm clipping remains largely unknown.

METHODS

Patients with aSAH who underwent clipping surgery within 72 hours from bleeding were included. The patients in the ANH group received 400 mL autologous blood collection, and the blood was returned as needed during surgery. The relationships between ANH and perioperative allogeneic blood transfusion, postoperative outcome, and complications were analyzed.

RESULTS

Sixty-two patients with aSAH were included between December 2019 and June 2020 (20 in the ANH group and 42 in the non-ANH group). ANH did not reduce the need of perioperative blood transfusion (3 [15%] vs. 5 [11.9%]; P = 0.734). However, ANH significantly increased serum hemoglobin levels on postoperative day 1 (11.5 ± 2.5 g/dL vs. 10.3 ± 2.0 g/dL; P = 0.045) and day 3 (12.1 ± 2.0 g/dL vs. 10.7 ± 1.3 g/dL; P = 0.002). Multivariable analysis indicated that serum hemoglobin level on postoperative day 1 (odds ratio, 0.895; 95% confidence interval, 0.822-0.973; P = 0.010) was an independent risk factor for unfavorable outcome, and receiver operating characteristic curve analysis showed that it had a comparable predictive power to World Federation of Neurosurgical Societies grade (Z = 0.275; P > 0.05).

CONCLUSIONS

ANH significantly increased postoperative hemoglobin levels, and it may hold the potential to improve patients' outcomes. Routine use of ANH should be considered in aneurysm clipping surgery.

[Role of acute hemodilution in blood transfusion rate in patients submmited to scoliosis surgery: observational retrospective study]

BACKGROUND AND OBJECTIVES

The study assessed the role of acute hemodilution in the blood transfusion rate in patients submitted to surgical treatment of scoliosis.

METHODS

Retrospective observational study performed at Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo (HC-FMRP?USP). Medical charts of patients submitted to elective correction of scoliosis between January 1996 and December 2016 were analyzed. Variables assessed were: age, weight, sex, presence of comorbidities, data regarding anesthesia and surgery, lab data, adverse events and blood transfusion rate. The final sample consisted of 33 procedures performed by the same anesthesiologist and same surgeon, divided into two groups: Hemodilution Group (n = 16) and Control Group (n = 17). Indication of acute normovolemic hemodilution was determined by patient refusal of blood transfusion for religious reasons.

RESULTS

The sample was statistically homogeneous and the groups were compared in terms of the attributes analyzed. The volume of homologous blood used by the Hemodilution Group was significantly lower than the Control Group (p = 0.0016). The percentage of patients who required transfusion was 12.5% in the Hemodilution Group, while it was 70.69% (p = 0.0013) in the Control Group. Upon hospital discharge, mean values of hemoglobin and hematocrit between groups did not present significant differences (p = 0.0679; p = 0.1027, respectively).

CONCLUSIONS

Acute normovolemic hemodilution, in scoliosis correction surgeries reduces blood transfusion rates, meeting patient needs without increasing adverse events or infection rates.

Role of acute hemodilution in blood transfusion rate in patients submitted to scoliosis surgery: observational retrospective study

Background and objectives

The study assessed the role of acute hemodilution in the blood transfusion rate in patients submitted to surgical treatment of scoliosis.

Methods

Retrospective observational study performed at Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo (HC-FMRP–USP). Medical charts of patients submitted to elective correction of scoliosis between January 1996 and December 2016 were analyzed. Variables assessed were: age, weight, sex, presence of comorbidities, data regarding anesthesia and surgery, lab data, adverse events and blood transfusion rate. The final sample consisted of 33 procedures performed by the same anesthesiologist and same surgeon, divided into two groups: Hemodilution Group (n = 16) and Control Group (n = 17). Indication of acute normovolemic hemodilution was determined by patient refusal of blood transfusion for religious reasons.

Results

The sample was statistically homogeneous and the groups were compared in terms of the attributes analyzed. The volume of homologous blood used by the Hemodilution Group was significantly lower than the Control Group (p = 0.0016). The percentage of patients who required transfusion was 12.5% in the Hemodilution Group, while it was 70.69% (p = 0.0013) in the Control Group. Upon hospital discharge, mean values of hemoglobin and hematocrit between groups did not present significant differences (p = 0.0679; p = 0.1027, respectively).

Conclusions

Acute normovolemic hemodilution, in scoliosis correction surgeries, reduces blood transfusion rates, meeting patient needs without increasing adverse events or infection rates.

Acute Normovolemic Hemodilution in Spinal Deformity Surgery

Objective  To prospectively compare the clinical and laboratorial aspects of patients undergoing spine deformity surgery, using the acute normovolemic hemodilution technique with tranexamic acid, versus a control group with tranexamic acid alone, and to evaluate the influence of hemodilution in intraoperative bleeding and the need for homologous transfusion.

Materials and Methods  Comparative prospective study with patients aged between 12 and 65 years undergoing spine deformity surgery with the acute normovolemic hemodilution technique associated with tranexamic acid versus a control group to which only tranexamic acid (15 mg/kg) was administered. Laboratorial exams were performed and analyzed in three different moments.

Results  A total of 30 patients were included in the present study: 17 in the hemodilution group, and 13 in the control group. The mean duration of the surgery in the hemodilution group was longer. The number of levels submitted to surgery ranged from 7 to 16 in the hemodilution group, and from 4 to 13 in the control group. Osteotomy, predominantly of the posterior kind, was performed in 20 patients. There was more intraoperative bleeding in the control group. All patients were stable during the procedures. Only 6 participants needed homologous blood transfusion, mostly from the control group ( p  > 0.05).

Conclusion  There was no significant difference between the two groups regarding the need for blood transfusion and intraoperative bleeding. The severity of the deformity was the main determinant for homologous blood transfusion.

Myocardial oxygen balance during acute normovolemic hemodilution: A novel compartmental modeling approach

BACKGROUND

Hemodilution was introduced initially as a blood conservation technique to reduce allogeneic blood transfusion in patients undergoing surgical procedures. Although the technique has been approved by the National Institute of Health consensus panel, limits of hemodilution under anesthetic conditions have not been established as they have in animal models.

METHODS

A novel multi-compartmental modeling approach has been proposed that includes the effect of anesthesia to quantify the effect of hemodilution on myocardial oxygen balance during myocardial ischemia.

RESULTS

The results showed that isovolemic hemodilution would cause detrimental effects around a hematocrit of 15%. Even though the fall in oxygen content caused by the decrease in hemoglobin concentration was compensated by an increase in coronary blood flow induced by hypoxic vasodilation and decreased viscosity, the endocardial tissue received less oxygen compared to the epicardial regions, and this sub-endocardial ischemia eventually led to cardiac failure. Statistical analysis also showed that the type of acellular replacement fluid failed to affect the heart rate, the stroke index or the cardiac index during hemodilution, and supplemental oxygen improved the endocardial oxygen supply.

CONCLUSION

The model validates the clinical conclusions that sub-endocardial ischemia causes cardiac failure under extreme hemodilution conditions and the model can also be easily integrated into other human simulators.

Anaemia and red blood cell transfusion in intracranial neurosurgery: a comprehensive review

Both anaemia and blood transfusion are associated with poor outcomes in the neurosurgical population. Based on the available literature, the optimal haemoglobin concentration for neurologically injured patients appears to be in the range of 9.0-10.0 g dl^-1, although the individual risks and benefits should be weighed. Several perioperative blood conservation strategies have been used successfully in neurosurgery, including correction of anaemia and coagulopathy, use of antifibrinolytics, and intraoperative cell salvage. Avoidance of non-steroidal anti-inflammatory drugs and starch-containing solutions is recommended given the potential for platelet dysfunction.

Evaluation of acute normovolemic hemodilution in patients undergoing intracranial meningioma resection: A quasi-experimental trial

The aim of this study was to evaluate the safety of acute normovolemic hemodilution (ANH) for patients undergoing intracranial meningioma resection.Eighty patients (aged 48-65 years) with American Society of Anesthesiologists physical status I-II undergoing intracranial meningioma resection were included in this prospective observational study. The patients were randomly divided into group A (ANH group), which underwent a combination of ANH and intraoperative cell salvage (ICS), and group B (control group), which underwent ICS alone. The study parameters were recorded as baseline values before blood drainage (T0), after blood drainage (T1), and before (T2) and after (T3) retransfusion in group A. Whereas in group B, the same parameters were measured 10 minutes after anesthesia induction (T0), before surgery (T1), and before (T2) and after (T3) transfusion of autologous blood.When intraoperative blood loss was <2000 mL, the mean volume of homologous blood transfused in group A patients was 100.8 ± 82.3 mL, compared with the 190.0 ± 91.8 mL in group B. Reduction in homologous blood used in group A was statistically significant (P < .05). In group B, 15.1% patients received homologous blood, whereas only 5.9% patients received homologous blood in group A. The difference in heart rate between both groups at different time points was statistically nonsignificant (P > .05). The mean hemoglobin and hematocrit levels at T1 and T2 in group A were lower than in group B (P < .05). The prothrombin time and activated partial thromboplastin time in both groups were prolonged significantly after T2 (all P < .05), but were all within normal range. There were no significant differences in postoperative hospital stay, mortality, and postoperative infection between the 2 groups.For patients undergoing excision of intracranial meningioma, ANH is an effective procedure to reduce the need for allogeneic transfusions.

A review of the application of autologous blood transfusion

Autologous blood transfusion (ABT) has been gradually attracting more attention due to the increasingly prominent problem of blood transfusion safety and blood shortage in recent years. With the rapid development of blood conservation techniques, blood component separation technology, blood transfusion medicine and a constant increase in clinical needs, ABT technology has been expanded and innovated to a large degree. In this study, the development of preoperative autologous blood donation (PABD), acute normovolemic hemodilution (ANH), intraoperative and postoperative autotransfusion, and other new technologies and theories are reviewed and existing questions are analyzed. Challenges and applications are also discussed in order to provide reference for peers.

Acute normovolemic hemodilution to avoid blood transfusion during intracranial aneurysm surgery in a patient with atypical antibodies

Acute normovolemic haemodilution (ANH) has been used in neurosurgical operations to reduce the incidence of homologous blood transfusions. We report a case of anterior communicating artery aneurysm in a patient with atypical antibodies in the serum, who was posted for clipping of the said aneurysm, and was managed with ANH in the perioperative period in order to avoid blood transfusions.

A novel approach to modeling acute normovolemic hemodilution

Acute normovolemic hemodilution (ANH) was introduced as a blood conservation technique to reduce patient exposure to allogenic blood transfusion during surgery. Despite years of research and experience, the best practice procedure, efficacy and safety of ANH remain in question. In this work, a numerical model is developed for the ANH procedure based upon a multi-compartmental, fluid model of the body. The model also analyzes the most commonly used acellular fluids for ANH or for fluid therapy following hemorrhage. The model allows user input of critical ANH parameters, providing the ability to simulate the patient׳s response in real time to many clinical scenarios, using various types of resuscitation fluids. First, the patient׳s response to a representative, clinical ANH protocol and surgery was simulated. Then, the effect of several variables was investigated including: type/amount of resuscitation fluid, number of blood units collected during ANH, and amount of surgical blood loss. Our simulations highlighted the importance of osmotic molecules within the blood in preventing excessive fluid retention and initiating fluid clearance after surgery. The developed model can be utilized as a tool to simulate and optimize a variety of proposed protocol related to the ANH procedure and surgery. It can also be utilized as an educational or training tool to become familiar with the ANH procedure.

Red blood cell transfusion in neurosurgical patients

PURPOSE OF REVIEW

Anemia is common in neurosurgical patients, and is associated with secondary brain injury. Although recent studies in critically ill patients have shifted practice toward more restrictive red blood cell (RBC) transfusion strategies, the evidence for restrictive versus liberal transfusion strategies in neurosurgical patients has been controversial. In this article, we review recent studies that highlight issues in RBC transfusion in neurosurgical patients.

RECENT FINDINGS

Recent observational, retrospective studies in patients with traumatic brain injury, subarachnoid hemorrhage, and intracranial hemorrhage have demonstrated that prolonged anemia and RBC transfusions were associated with worsened outcomes. Anemia in patients with ischemic stroke was associated with increased ICU length of stay and longer mechanical ventilation requirements, but mortality and functional outcomes did not improve with RBC transfusion. In elective craniotomy, perioperative anemia was associated with increased hospital length of stay but no difference in 30-day morbidity or mortality.

SUMMARY

There is a lack of definitive evidence to guide RBC transfusion practices in neurosurgical patients. Large randomized control trials are needed to better assess when and how aggressively to transfuse RBCs in neurosurgical patients.

Hypotensive anesthesia versus normotensive anesthesia during major maxillofacial surgery: a review of the literature

Steady blood pressure within normal limits during surgery is one of the markers of the ideal and skillful anesthesia. Yet, reduced blood pressure is advantageous in some settings because it can contribute to a reduction in overall blood loss and improve the surgical field conditions. Controlled hypotension during anesthesia or hypotensive anesthesia is often used in major maxillofacial operations. Since hypotensive anesthesia carries the risk of hypoperfusion to important organs and tissues, mainly the brain, heart, and kidneys, it cannot be applied safely in all patients. In this paper we review the medical literature regarding hypotensive anesthesia during major maxillofacial surgery, the means to achieve it, and the risks and benefits of this technique, in comparison to normotensive anesthesia.