Acute normovolemic hemodilution

Acute normovolemic hemodilution in cardiac surgery: Rationale and design of a multicenter randomized trial

BACKGROUND

Minimizing the use of blood component can reduce known and unknown blood transfusion risks, preserve blood bank resources, and decrease healthcare costs. Red Blood Cell (RBC) transfusion is common after cardiac surgery and associated with adverse perioperative outcomes, including mortality. Acute normovolemic hemodilution (ANH) may reduce bleeding and the need for blood product transfusion after cardiac surgery. However, its blood-saving effect and impact on major outcomes remain uncertain.

METHODS

This is a single-blinded, multinational, pragmatic, randomized controlled trial with a 1:1 allocation ratio conducted in Tertiary and University hospitals. The study is designed to enroll patients scheduled for elective cardiac surgery with planned cardiopulmonary bypass (CPB). Patients are randomized to receive ANH before CPB or the best available treatment without ANH. We identified an ANH volume of at least 650 ml as the critical threshold for clinically relevant benefits. Larger ANH volumes, however, are allowed and tailored to the patient's characteristics and clinical conditions.

RESULTS

The primary outcome is the percentage of patients receiving RBCs transfusion from randomization until hospital discharge, which we hypothesize will be reduced from 35% to 28% with ANH. Secondary outcomes are all-cause 30-day mortality, acute kidney injury, bleeding complications, and ischemic complications.

CONCLUSION

The trial is designed to determine whether ANH can safely reduce RBC transfusion after elective cardiac surgery with CPB.

STUDY REGISTRATION

This trial was registered on ClinicalTrials.gov in April 2019 with the trial identification number NCT03913481.

Ethical issues in solid organ transplantation: transfusion-free transplantation in Jehovah's witness patients

PURPOSE OF REVIEW

Jehovah's Witnesses do not accept transfusion of major allogeneic blood fractions. Successful solid organ transplantation is challenging for Jehovah's Witnesses when anemia, coagulation disturbances, and difficult technical aspects co-exist, and key blood bank resources cannot be utilized. Organ availability for transplantation is limited and demand exceeds supply for all organ types. Historically, the likelihood of poor outcomes in Jehovah's Witnesses patients placed ethical limitations on transplant candidacy for this population violating the precept of maximal utilization of a limited resource. The review's purpose is to describe advancements and strategies that make Jehovah's Witnesses transplant outcomes comparable to transfusion-eligible patients and allay the ethical concerns of their candidacy.

RECENT FINDINGS

Immunomodulation from allogeneic transfusion is a cause of significant postop morbidity. Blood conservation strategies have led to improved outcomes across different medical and surgical cohorts and set the stage for expanded utility in Jehovah's Witnesses with organ insufficiency.Published single-center series with descriptions of specific peri-operative strategies describe the path to major blood product avoidance.

SUMMARY

Comparable outcomes in solid organ transplantation for Jehovah's Witnesses without allogeneic transfusion are possible when inclusion-exclusion criteria are respected, and blood conservation strategies employed.

Hemodilution in high-risk cardiac surgery: Laboratory values, physiological parameters, and outcomes

BACKGROUND

Acute normovolemic hemodilution (ANH) is a blood conservation strategy in cardiac surgery, predominantly used in coronary artery bypass graft (CABG) and/or valve procedures. Although higher complexity cardiac procedures may benefit from ANH, concerns for hemodynamic instability, and organ injury during hemodilution hinder its wider acceptance. Laboratory and physiological parameters during hemodilution in complex cardiac surgeries have not been described.

STUDY DESIGN AND METHODS

This observational cohort (2019-2021) study included 169 patients who underwent thoracic aortic repair, multiple valve procedure, concomitant CABG with the aforementioned procedure, and/or redo sternotomies. Patients who received allogeneic blood were excluded. Statistical comparisons were performed between ANH (N = 66) and non-ANH controls (N = 103). ANH consisted of removal of blood at the beginning of surgery and its return after cardiopulmonary bypass.

RESULTS

Intraoperatively, the ANH group received more albumin (p = .04) and vasopressor medications (p = .01), while urine output was no different between ANH and controls. Bilateral cerebral oximetry (rSO₂ ) values were similar before and after hemodilution. During bypass, rSO₂ were discretely lower in the ANH versus control group (right rSO₂ p = .03, left rSO₂ p = .05). No differences in lactic acid values were detected across the procedural continuum. Postoperatively, no differences in extubation times, intensive care unit length of stay, kidney injury, stroke, or infection were demonstrated.

DISCUSSION

This study suggests hemodilution to be a safe and comparable blood conservation technique, even without accounting for potential benefits of reduced allogenic blood administration. The study may contribute to better understanding and wider acceptance of ANH protocols in high-risk cardiac surgeries.

Effects of acute normovolemic hemodilution on post-cardiopulmonary bypass coagulation tests and allogeneic blood transfusion in thoracic aortic repair surgery: An observational cohort study

BACKGROUND AND AIM

Perioperative blood transfusion is associated with increased morbidity and mortality. Acute normovolemic hemodilution (ANH) is a blood conservation strategy associated with variable success, and rarely studied in more complex cardiac procedures. The study aim was to evaluate whether ANH improves coagulopathy and reduces blood transfusions in thoracic aortic surgeries.

METHODS

Single-center observational cohort study comparing ANH and standard institutional practice in patients who underwent thoracic aortic repair with cardiopulmonary bypass (CPB) from 2019 to 2021.

RESULTS

A total of 89 patients underwent ANH and 116 standard practice. There were no significant differences between the groups in terms of demographic or major perioperative characteristics. In the ANH group coagulation tests before and after transfusion of autologous blood showed decreased INR and increased platelets, fibrinogen, all with p < 0.0005. Coagulation results in the ANH and control groups were not statistically different. The average number of transfused allogeneic products per patient was lower in the ANH versus control group: FFP 1.1 ± 1.6 versus 1.9 ± 2.3 (p = 0.003), platelets 0.6 ± 0.8 versus 1.2 ± 1.3 (p = 0.0008), and cryoprecipitate 0.3 ± 0.7 versus 0.7 ± 1.1 (p = 0.008). Reduction in red blood cell transfusion was not statistically significant. The percentage of patients who received any transfusion was 53.9% in ANH and 59.5% in the control group (p = 0.42). There was no significant difference in major adverse outcomes.

CONCLUSIONS

ANH is a safe blood conservation strategy for surgical repairs of the thoracic aorta. Laboratory data suggests ANH can improve some coagulation values after separation from CPB, and significantly reduce the number of transfused FFP, platelets and cryoprecipitate.

Prepump autologous blood collection is associated with reduced intraoperative transfusions in aortic surgery with circulatory arrest: A propensity score-matched analysis

OBJECTIVE

To evaluate the effect of autologous whole blood (AWB) collection on intraoperative/postoperative allogeneic blood transfusion rate in complex aortic surgery with hypothermic circulatory arrest.

METHODS

This retrospective study included adults who underwent aortic surgery with hypothermic circulatory arrest at a single institution between 2014 and 2019. Out of 509 cases (414 patients), 110 (22%) received the AWB protocol. We performed propensity-score matching, including 35 preoperative and procedural variables, which resulted in 95 well-matched pairs, to compare outcomes in patients who received AWB protocol versus those who did not. Study outcomes were percentage of patients who received transfusion of allogeneic blood products intraoperatively and postoperatively.

RESULTS

Mean volume of collected autologous blood was 826 ± 263 mL. Intraoperatively, fewer AWB patients received red blood cell concentrate (33% vs 49%; P = .02), plasma (35% vs 62%; P = .0002), platelets (61% vs 81%; P = .003), and cryoprecipitate (43% vs 56%; P = .08) compared with non-AWB patients. During the entire hospital stay, the differences in transfusion rate between the 2 groups were: red blood cells (58% vs 62%; P = .6), plasma (49% vs 66%; P = .01), platelets (72% vs 82%; P = .09), and cryoprecipitate (56% vs 63%; P = .3).

CONCLUSIONS

Pre-pump autologous blood collection may reduce the need for intraoperative transfusion of allogenic non-red-cell blood products in patients undergoing complex aortic surgery with hypothermic circulatory arrest. A larger study is needed to clarify the influence of this association on patient outcomes and resource utilization.

Review of abdominal solid organ transplantation in Jehovah’s Witness patients

Managing blood loss in Jehovah’s Witness (JW) patients is a matter of controversy. These patients will not accept transfusions of red blood cells, white blood cells, platelets or plasma, even if that is required to save their lives. There are many discussions regarding safety of operating upon JW patients in general surgical procedures, but in solid organ transplantation there is a paucity of literature on this subject. We have reviewed individual case reports and small series documenting on experience with solid organ transplantation in JW patients and the strategies adopted to facilitate that. It is clear that such patients require the surgical team to dedicate more time to ensure their safe management. This begins with a thorough, detailed consent of exactly which products and interventions they will or will not accept. Planning must begin weeks before surgery if possible. Each case must be assessed individually, but provided they meet fitness requirements, there are no absolute contraindications to abdominal organ transplantation.

Validating the Physiologic Model HumMod as a Substitute for Clinical Trials Involving Acute Normovolemic Hemodilution

BACKGROUND

Blood conservation strategies and transfusion guidelines remain a heavily debated clinical topic. Previous investigational trials have shown that acute isovolemic hemodilution does not limit adequate oxygen delivery; however, a true critical hemoglobin level has never been investigated or defined due to safety concerns for human volunteers. Validated physiologic modeling may be useful to investigate hemodilution at critical hemoglobin levels without the ethical or safety hazards of clinical trials. Our hypothesis is that HumMod, an integrative physiological model, can replicate the cardiovascular and metabolic findings of previous clinical studies of acute isovolemic hemodilution and use coronary blood flow and coronary oxygen delivery in extreme hemodilution to predict a safety threshold.

METHODS

By varying cardiovascular and sizing parameters, unique individuals were generated to simulate a population using HumMod, an integrative mathematical model of human physiology. Hemodilution was performed by simultaneously hemorrhaging 500 mL aliquots of blood while infusing equal volumes of hetastarch, 5% albumin balanced salt solution, or triple volumes of lactated Ringer's solution over 10 minutes. Five hemodilution protocols reported over 3 studies were directly replicated with HumMod to compare and validate essential cardiovascular and metabolic responses to hemodilution in moderately healthy, awake adults. Cardiovascular parameters, mental status, arterial and mixed venous oxygen content, and oxyhemoglobin saturation were recorded after the removal of each aliquot. The outputs of this simulation were considered independent variables and were stratified by hemoglobin concentration at the time of measurement to assess hemoglobin as an independent predictor of hemodynamic and metabolic behavior.

RESULTS

The published reports exhibited discrepancies: Weiskopf saw increased heart rate and cardiac index, while Jones and Ickx saw no change in these variables. In HumMod, arterial pressure was maintained during moderate hemodilution due to decreases in peripheral resistance opposing increases in cardiac index. HumMod showed preserved ventilation through moderate hemodilution, compensated for by an increased oxygen extraction similar to the studies of Jones and Ickx. The simulation results qualitatively followed the clinical studies, but there were statistical differences. In more extreme hemodilution, HumMod had a lesser increase in cardiac index, which led to deficiencies in oxygen delivery and low venous saturation. In the simulations, coronary blood flow and oxygen delivery increase up to a critical hemoglobin threshold of 55-75 g/L in HumMod. In this range, coronary blood flow and oxygen delivery fell, leading to cardiac injury. The allowable amount of hemodilution before reaching the critical point is most closely correlated with nonmuscle mass (r = 0.69) and resting cardiac output (r = 0.67).

CONCLUSIONS

There were significant statistical differences in the model population and the clinical populations, but overall, the model responses lay within the clinical findings. This suggests our model is an effective replication of hemodilution in conscious, healthy adults. A critical hemoglobin range of 5.5-7.5 g/L was predicted and found to be highly correlated with nonmuscle mass and resting cardiac output.

Treatment of individuals who cannot receive blood products for religious or other reasons

By virtue of their religious principles, Jehovah's Witnesses (JWs) generally object to receiving blood products, raising numerous ethical, legal, and medical challenges for providers who care for these patients, especially in the emergent setting. In this review, we discuss several areas relevant to the care of JWs, including the current literature on "bloodless" medical care in the setting of perioperative and intraoperative management, acute blood loss, trauma, pregnancy, and malignancy. We have found that medical and administrative efforts in the form of bloodless medicine and surgery programs can be instrumental in helping to reduce risks of morbidity and mortality in these patients. Planning prior to an anticipated event associated with blood loss or anemia (such as elective surgery, pregnancy, and chemotherapy) is critical. Specifically, bloodless medicine programs should prioritize vigilant early screening and management of anemias, early establishment of patient wishes regarding transfusion, and the incorporation of those wishes into multidisciplinary medical and surgical care. Although there are now a variety of human-based and nonhuman-based products available as transfusion alternatives, the degree and quality of evidence to support their use varies significantly between products and is also largely dependent on the clinical setting.

The effectiveness of acute normolvolemic hemodilution and autologous prime on intraoperative blood management during cardiac surgery

Objective:

Intraoperative blood management during cardiac surgery is a multifaceted process incorporating various interventions directed at optimizing oxygen delivery and enhancing hemostasis. The purpose of this study was to evaluate the effects of acute normovolemic hemodilution (ANH) and autologous priming (AP) on preserving the hematocrit during cardiopulmonary bypass (CPB).

Method:

Case records from a national registry of adult patients who underwent cardiac surgery between January and October 2016 were reviewed. Groups were determined as follows: ANH, AP, ANH+AP or Neither. Primary endpoint was first the hematocrit on CPB with secondary endpoints of hematocrit drift and red blood cell (RBC) transfusion rate.

Results:

Eighteen thousand and twenty-four (18,024) consecutive patients were reviewed. The first CPB hematocrit was lowest in the ANH group (26.5%±4.4%) and highest in ANH+AP patients (27.5%±4.8%) (p<0.001). The change in hematocrit was greatest in the ANH group (8.3%±3.9%) compared to both the AP (6.4%±3.8%) and ANH+AP (6.9%±4.1%) groups (p<0.001). Intraoperative RBC transfusions were as follows: ANH 26 (7.8%), AP 2,531 (20.0%), ANH+AP 287 (10.3%) and Neither 592 (26.7%) (p<0.001).

Conclusions:

Regression results show that the use of ANH will result in the greatest decline in hematocrit values. When combined with AP, higher hematocrits and lower transfusions were seen.

Bloodless medicine: current strategies and emerging treatment paradigms

BACKGROUND

Advances in our understanding of the risks associated with allogeneic blood transfusions (ABTs) and the growing number of patients who wish to avoid ABTs have led to the emergence of new treatment paradigms for "bloodless" medicine and surgery.

STUDY DESIGN AND METHODS

Here, we review prior studies and summarize current strategies for bloodless care used at our institution. We advocate three basic principles: 1) diagnosing and aggressively treating anemia, 2) minimizing blood loss from laboratory testing and invasive procedures, and 3) identifying and managing bleeding diatheses. Anemia is treated with erythropoiesis-stimulating agents as well as iron, folate, and B12 when indicated. Low-volume phlebotomy tubes are used for laboratory testing. Autologous blood salvage is used for childbirth and surgical patients who have the potential for substantial bleeding.

RESULTS

Although there have been few retrospective studies and no prospective studies to guide management, prior studies suggest that outcomes for surgical patients managed without ABTs are comparable to those of historic controls.

CONCLUSIONS

Given the emerging evidence that patients who avoid ABTs do as well if not better than patients who accept ABTs, further efforts are needed to determine whether all patients could benefit from bloodless strategies. Bloodless approaches in selected patients could reduce risks, improve outcomes, and decrease costs for all patients.

Anesthetic management of a patient with polycythemia vera undergoing emergency repair of a type-A aortic dissection and concomitant coronary artery bypass grafting: a case report

Polycythemia vera is a chronic progressive myeloproliferative disease characterized by increased circulating red blood cells, and the hyperviscosity of the blood can lead to an increased risk of arterial thrombosis. In a previous survey regarding postoperative outcomes in polycythemia vera patients, an increased risk of both vascular occlusive and hemorrhagic complications have been reported. Aortic surgery involving cardiopulmonary bypass may be associated with the development of a coagulopathy, and as a result, the occurrence of thrombotic complications should be avoided after coronary anastomosis. Thus, optimizing the hemostatic balance is an important concern for anesthesiologists. However, only a few cases of anesthetic management in polycythemia vera patients undergoing concomitant aorta and coronary arterial bypass surgery have ever been reported. Here, we experience a polycythemia vera patient who underwent an emergency repair of a type-A aortic dissection and concomitant coronary artery bypass grafting, and report this case with a review of the relevant literature.

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.

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.

Modern Patient Blood Management in Arthroplasty

One of the oldest and still commonest procedures in clinical practice, allogeneic blood transfusion (ABT), is not fully supported by available evidence. In the last few decades, increasing concerns about unfavorable outcomes associated with ABT, anticipation of future insufficient blood supply, and awareness of the cost (direct and indirect) of transfusion have led to the promotion of patient blood management (PBM) as a cost-effective strategy, beneficial for patients as well as for society (Shander et al. 2010). PBM programs utilize a series of measures with a proven ability to reduce ABT and to be cost-effective. Despite that the impact of PBM on patient clinical outcomes needs to be fully defined and future studies are needed, PBM should be adopted as a new standard of care.

Stationary versus agitated storage of whole blood during acute normovolemic hemodilution

BACKGROUND

Acute normovolemic hemodilution is an intraoperative technique to reduce the number of red blood cells lost in shed blood during surgery. Standard guidelines for storage of platelets recommend constant gentle agitation to maintain gas exchange for the metabolically active platelets. The collected whole blood (WB) for acute normovolemic hemodilution remains stationary for as long as 8 hours before reinfusion. We hypothesized that gentle agitation of WB throughout storage would improve the coagulation properties of the WB at the time of reinfusion.

METHODS

WB was collected from 10 volunteer donors and control samples taken. The units were split in 2 storage groups: agitated (rocked) and stationary (unrocked). Cell counts and fibrinogen levels, as well as thromboelastography (TEG®) measurements, including TEG® PlateletMapping® assays, were performed on the control sample and the test samples after 8 hours of rocked or unrocked storage at room temperature.

RESULTS

Nine units WB from 9 different healthy volunteers were tested. There were no significant differences in hematocrit, hemoglobin, red blood cells counts, platelet counts, or fibrinogen levels between the control samples and the rocked and unrocked WB samples. WB coagulation as measured by TEG® was preserved during the 8-hour storage period in both the rocked and unrocked samples. There were no significant differences between the control, rocked, and unrocked samples in time to initiate clotting, time of clot formation, rate of clot formation, or maximum strength of clot values. There were also no significant differences in the fibrin contribution to clot strength between the control, rocked, and unrocked samples, and no significant difference between the platelet activation from adenosine diphosphate or arachidonic acid among any of the 3 groups.

CONCLUSIONS

Given the small sample size, there is no statistical evidence on which to reject the null hypothesis of there being no difference in the changes from the baseline between coagulation function as measured by TEG® between WB that is either agitated or kept stationary for 8 hours. These findings need to be confirmed in a larger study.

Blood utilization: fostering an effective hospital transfusion culture

An effective hospital transfusion culture should encourage clinicians to consider the possibility of transfusion in their patients well before the need actually arises, and to plan ahead in an attempt to use blood products most efficiently. Strategies for improved blood utilization include timely and adequate preoperative assessment of risk, optimization of baseline hemoglobin, anticipation of potential transfusion problems, intraoperative techniques to minimize blood loss, blood conservation technologies, transfusion guidelines and targeted therapy, point of care testing, and massive transfusion protocols. Attention to these elements promotes a safe and cost-effective transfusion culture.

Crystalloids versus colloids during acute normovolemic anemia: the quest continues

The optimal kind of fluid for fluid resuscitation during acute, severe hemorrhage is still discussed controversially. Of particular interest in this context is the choice of colloids versus crystalloids and their effect on the critical hemoglobin level. In a previous issue of Critical Care, Pape and colleagues describe the effect of four different volume replacement options on the critical hemoglobin concentration, and show marked differences for the different treatments. Even though some important pathophysiological issues remain unsolved, the current manuscript adds interesting evidence to an ongoing quest.

[The "Seville" Consensus Document on Alternatives to Allogenic Blood Transfusion. Sociedades españolas de Anestesiología (SEDAR), Medicina Intensiva (SEMICYUC), Hematología y Hemoterapia (AEHH), Transfusión sanguínea (SETS) Trombosis y Hemostasia (SETH)]

The Consensus Document on Alternatives to Allogenic Blood Transfusion (AABT) has been drawn up by a panel of experts from 5 scientific societies. The Spanish Societies of Anesthesiology (SEDAR), Critical Care Medicine and Coronary Units (SEMICYUC), Hematology and Hemotherapy (AEHH), Blood Transfusion (SETS) and Thrombosis and Hemostasis (SETH) have sponsored and participated in this Consensus Document. Alternatives to blood transfusion have been divided into pharmacological and non-pharmacological, with 4 modules and 12 topics. The main objective variable was the reduction of allogenic blood transfusions and/or the number of transfused patients. The extent to which this objective was achieved by each AABT was evaluated using the Delphi method, which classifies the grade of recommendation from A (supported by controlled studies) to E (non-controlled studies and expert opinion). The experts concluded that most of the indications for AABT were based on middle or low grades of recommendation, "C", "D", or "E", thus indicating the need for further controlled studies.

The use of a volatile anesthetic regimen protects against acute normovolemic hemodilution induced myocardial depression in patients with coronary artery disease

BACKGROUND

Previous studies indicated that acute normovolemic hemodilution (ANH) was associated with a depression of myocardial function in coronary surgery patients with baseline heart rate faster than 90 bpm. It was suggested that this phenomenon could be explained by the occurrence of myocardial ischemia. In the present study, we hypothesized that the cardioprotective properties of a volatile anesthetic regimen might protect against the ANH related myocardial functional impairment.

MATERIALS AND METHODS

Forty elective coronary surgery patients with baseline heart rate faster than 90 bpm were randomly allocated to receive different anesthetic regimens. Group A (n = 20) received midazolam-based anesthesia. Group B (n = 20) received a sevoflurane-based anesthesia. Five-lead electrocardiogram, pulse oximetry, capnography, radial arterial pressure, and Swan Ganz continuous thermodilution cardiac output via right internal jugular vein were monitored. Measurements were obtained before and after ANH. Data were compared using paired t test. All data were expressed as mean +/- SD. Data were considered significant if P < 0.05.

RESULTS

After ANH, systemic vascular resistance was slightly decreased in group A while there was a significant decrease in group B. In group A, cardiac output was slightly decreased from 5.07+/-1.17 l/min to 5.02+/-1.28 l/min after ANH, whereas in group B, cardiac output was significantly increased from 4.84+/-1.21 l/min to 6.02+/-1.28 l/min after ANH.

CONCLUSION

In coronary surgery patients, with baseline heart rate faster than 90 bpm, anesthesia with sevoflurane during ANH was associated with an improvement in myocardial function after ANH, which was not present in patients anesthetized with midazolam.

The role of the anesthesiologist in management of obstetric hemorrhage

Hemorrhage after childbirth, whether the delivery is vaginal or operative, is a clinical situation where knowledge, communication, and the availability and utilization of resources all play prominent roles. In this article we describe the thought processes and decisions that should occur, and the actions that should be taken by the anesthesiologist in the face of suspected, expected, or unexpected hemorrhage in the labor and delivery suite.

Three new high-prevalence antigens in the Cromer blood group system

BACKGROUND

The Cromer blood group system consists of nine high-prevalence and three low-prevalence antigens carried on decay-accelerating factor (DAF). This report describes three new Cromer high-prevalence antigens, named ZENA, CROV, and CRAM.

STUDY DESIGN AND METHODS

Sequence analyses were performed on DNA from three probands whose serum samples each contained an alloantibody to a high-prevalence antigen in the Cromer blood group system. Polymerase chain reaction-restriction fragment length polymorphism analysis to detect the mutation encoding the CROV- phenotype was performed on 100 Croatian donors. To map the respective epitopes, DAF deletion mutants were tested by immunoblotting with eluates containing the antibodies.

RESULTS

In each proband, sequence analysis revealed a single-nucleotide substitution in DAF: ZENA, 726T>G mutation, predicted change His242Gln; CROV, 466G>A mutation, predicted change Glu156Lys; and CRAM, 740A>G mutation, predicted change Gln247Arg. By analysis of DAF deletion mutants, the CROV antigenic determinant mapped to the complement control protein (CCP) domain 2, which is encoded by exon 3, whereas ZENA and CRAM mapped to CCP4, which is encoded by exon 6.

CONCLUSION

This study describes three novel high-prevalence antigens in the Cromer blood group system each characterized by a predicted single-amino-acid substitution. The antigens have been assigned the following International Society of Blood Transfusion (ISBT) numbers: ZENA is CROM13, CROV is CROM14, and CRAM is CROM15.

Ten years of preoperative autologous blood donation in accra

SUMMARY BACKGROUND

Preoperative autologous blood donation (PABD) is utilized to circumvent the use of allogenic blood for various reasons.

OBJECTIVE

To describe the distribution in terms of demographic characteristic, trends in participation and result of screening test of the PABD programme of the Accra Area Blood Center from 1993-2003.

DESIGN AND SETTING

Retrospective descriptive study of PABD in patients scheduled for a variety of elective surgical procedures.

SETTING

Different levels of institutional health care in Accra, Ghana.

METHODS

Data from existing records of patients who had participated in PABD were collated and analyzed

RESULTS

Five hundred and forty six (546) females and 89 males participated, with ages ranging between 14-74 years. Majority of the patients (76.7%) underwent gynaecological surgery. A total of 330 (52%) donated one unit only, and 299 (47.1%) donated two units. Majority of the patients (56.4%) had the surgery at the Korle-Bu Teaching Hospital (KBTH). Of the donations, 21 (3.3%), 1 (0.2%), 1 (0.3%) and nil were positive for HBV, HIV I & II, HCV and VDRL respectively. A total of 848 (89.4%) autologous cross-matched units were issued out. There was a steady progressive increase in participation.

CONCLUSION

Mainly adult females scheduled for gynaecological surgeries in KBTH participated, while almost equal proportions donated one or two units of blood which meets the blood needs of most elective surgeries. Therefore healthy patients going for elective surgeries in regions with limited blood supply must be encouraged to enter a PABD Programme. Further studies in this field should evaluate motivational factors for participation.

Cardioprotective effects of acute normovolemic hemodilution in patients with severe aortic stenosis undergoing valve replacement

BACKGROUND

After acute normovolemic hemodilution (ANH), improvement of the rheologic conditions may contribute to optimize tissue oxygen delivery and attenuate ischemia-reperfusion injuries. It was hypothesized that ANH would confer additional cardioprotection in patients with ventricular hypertrophy undergoing open heart surgery.

STUDY DESIGN AND METHODS

This study was a randomized controlled trial. Forty patients scheduled for elective aortic valve replacement were randomly assigned to a control group (standard care) or an ANH group (target hematocrit level of 28%). All patients were managed with standard myocardial preservation techniques (cold blood cardioplegia, anesthetic preconditioning). The outcome measures included the release of myocardial enzymes, perioperative hemodynamic changes, the need for pharmacologic cardiovascular support, and cardiac complications.

RESULTS

In the ANH group, the postoperative release of troponin I (mean peak plasma concentrations, 1.7 ng/mL; 95% confidence interval, 1.4-2.1 ng/mL) and myocardial fraction of creatine kinase (22 U/L; range, 18-24 U/L) was significantly lower than in the control group (3.6 [range, 3.0-4.2] ng/mL and 45 [range, 39-51] U/L, respectively). In addition, requirement for inotropic support was significantly lower and fewer hemodiluted patients presented adverse cardiac events. After ANH, there was a significant decrease in heart rate (-11 +/- 6%) and rate-pressure product (-16 +/- 8%) until the aortic cross-clamping time and, at the end of surgery, the circulating levels of erythropoietin (EPO) were higher than in control patients (13.6 +/- 4.2 mUI/mL vs. 7.3 +/- 2.4 mUI/mL; p < 0.05).

CONCLUSIONS

Besides conventional cardiac preservation techniques, preoperative ANH further attenuates myocardial injuries. Optimization of preischemic myocardial oxygen delivery and/or consumption and the postconditioning effects of endogenous EPO are potential mechanisms for ANH-induced cardioprotection.

Case report and literature review: transient Inab phenotype and an agglutinating anti-IFC in a patient with a gastrointestinal problem

BACKGROUND

The Inab phenotype is a rare deficiency of all Cromer antigens. These antigens are carried on the decay-accelerating factor (DAF, CD55) molecule that is attached to the red blood cell (RBC) membrane by a glycosylphosphatidylinositol (GPI) anchor. Although typically inherited, an acquired and transient form of the Inab phenotype also exists. A patient with the triad of transient Inab phenotype, a direct-agglutinating anti-IFC, and gastrointestinal (GI) abnormalities is reported.

CASE REPORT

An 18-month-old boy with gastroesophageal reflux disease requiring a feeding tube, milk and soy intolerance, and severe growth retardation, as well as vision and hearing deficits from cytomegalovirus infection, was identified when pretransfusion testing revealed a potent panagglutinin (titer > 2000 at 4 degrees C). This antibody did not react with Dr(a-) and IFC RBCs, and the autocontrol was negative. The patient's RBCs lacked CD55 by flow cytometric techniques but had normal levels of CD59 and antigens such as Yt(a) and Emm, carried on GPI-linked proteins, thus excluding paroxysmal nocturnal hemoglobinuria. Several months after initial detection, the anti-IFC was virtually undetectable and his cells reacted weakly with anti-IFC, anti-Dr(a), and anti-CD55. RBCs from the propositus' parents and brother demonstrated normal CD55 and CD59 expression.

CONCLUSION

This is the first example of a direct-agglutinating anti-IFC. The cause of the transient depression in CD55 protein (and thus Cromer system antigens) and appearance of anti-IFC remains unknown, as does the relationship between the patient's GI system abnormalities and these serologic findings.