Indications for red cell transfusion in sickle cell disease

Euvolemic automated transfusion to treat severe anemia in sickle cell disease patients at risk of circulatory overload

BACKGROUND

Red blood cell (RBC) transfusion remains a major treatment for sickle cell disease (SCD). Patients with SCD have a high prevalence of renal impairment and cardiorespiratory disease, conferring risk of transfusion-associated circulatory overload (TACO).

STUDY DESIGN AND METHODS

We describe an approach, titled euvolemic automated transfusion (EAT), to transfuse SCD patients with severe anemia who are at risk of TACO. In EAT, plasmapheresis is performed using donor RBCs, rather than albumin or plasma, as replacement fluid. Euvolemia is maintained. A retrospective analysis was conducted of patients with SCD who underwent EAT at our institution over a 10-year period, to evaluate the efficacy and safety of EAT.

RESULTS

Eleven SCD patients underwent 109 EAT procedures (1-59 procedures per patient). The median age was 42 years (IQR = [30-49]) and 82% (n = 9) were female. Most (82%; n = 9) patients had severe chronic kidney disease and 55% (n = 6) had heart failure. One (9%) patient had a history of life-threatening TACO. Mean pre- and post-procedure Hct values were 19.8% (SD ± 1.6%) and 29.1% (SD ± 1.4%), respectively. The average Hct increment was 3.2% per RBC unit. Only two EAT-related complications were recorded during the 109 procedures: central line-associated infection and citrate toxicity (muscle cramping). EAT used an average of two RBC units less than that projected for standard automated RBC exchange.

CONCLUSION

Our findings suggest that EAT is safe and effective to treat patients with SCD and severe anemia, who are at risk for TACO. EAT requires fewer RBC units compared to automated RBC exchange.

Preoperative Transfusion and Surgical Outcomes for Children with Sickle Cell Disease

BACKGROUND

Current guidelines recommending preoperative transfusion to a hemoglobin level of 9 to 10 g/dL for patients with sickle cell disease (SCD) are based on imperfect evidence. The benefit of preoperative transfusion in children specifically is not known. This study aimed to evaluate whether preoperative RBC transfusion is associated with different rates of sickle cell crisis and surgical complications, compared with no preoperative transfusion, among children with SCD undergoing common abdominal operations.

STUDY DESIGN

The NSQIP-Pediatrics database (2013 to 2019) was queried. Patients who underwent cholecystectomy, splenectomy, or appendectomy with a preoperative Hct level of less than 30% were included. The primary outcome was 30-day readmission for sickle cell crisis. Secondary outcomes were 30-day surgical complications and hospital length of stay. Propensity score matching methods were used to obtain two statistically similar cohorts of patients comprised of those who were preoperatively transfused and those who were not.

RESULTS

Among 357 SCD patients, 200 (56%) received preoperative transfusion. In the matched cohort of 278 patients (139 per group), there was no statistically significant difference in 30-day readmission for sickle cell crisis in the transfused and non-transfused groups (5.8% vs 7.2%, p = 0.80). The rate of 30-day surgical complications did not differ between matched groups (10.8% vs 9.4%, p = 0.84). Subgroups defined by presenting Hct levels of 27.3% or greater or less than 27.3%, American Society of Anesthesiologists classification, wound class, and index operation were not associated with an altered risk of sickle cell crisis or surgical complications after preoperative transfusion compared with no transfusion.

CONCLUSIONS

Preoperative transfusion for children with SCD undergoing semi-elective abdominal operations was not associated with improved outcomes. Prospective investigation is warranted to strengthen guidelines and minimize unnecessary perioperative transfusions in this population.

Red blood cell exchange in patients with sickle cell disease-indications and management: a review and consensus report by the therapeutic apheresis subsection of the AABB

BACKGROUND

A prior practice survey revealed variations in the management of patients with sickle cell disease (SCD) and stressed the need for comprehensive guidelines. Here we discuss: 1) common indications for red blood cell exchange (RCE), 2) options for access, 3) how to prepare the red blood cells (RBCs) to be used for RCE, 4) target hemoglobin (Hb) and/or hematocrit (Hct) and HbS level, 5) RBC depletion/RCE, and 6) some complications that may ensue.

STUDY DESIGN AND METHODS

Fifteen physicians actively practicing apheresis from 14 institutions representing different areas within the United States discussed how they manage RCE for patients with SCD.

RESULTS

Simple transfusion is recommended to treat symptomatic anemia with Hb level of less than 9 g/dL. RCE is indicated to prevent or treat complications arising from the presence of HbS. The most important goals are reduction of HbS while also preventing hyperviscosity. The usual goals are a target HbS level of not more than 30% and Hct level of less than 30%.

CONCLUSION

Although a consensus as to protocol details may not be possible, there are areas of agreement in the management of these patients, for example, that it is optimal to avoid hyperviscosity and iron overload, that a target Hb S level in the range of 30% is generally desirable, and that RCE as an acute treatment for pain crisis in the absence of other acute or chronic conditions is ordinarily discouraged.

Possible Risk Factors for Severe Anemia in Hospitalized Sickle Cell Patients at Muhimbili National Hospital, Tanzania: Protocol for a Cross-Sectional Study

Background

Sickle cell disease (SCD) is the most common inherited disorder worldwide, with the highest burden in sub-Saharan Africa. The natural history of SCD is characterized by periods of steady state interspersed by acute episodes. The acute anemic crises may be transient and are precipitated by treatable factors like infections, nutritional deficiencies, and sequestration. Anemia is almost always present, although it occurs at different levels of severity.

Objective

This paper describes the protocol of a cross-sectional study to determine the prevalence of severe anemia and associated factors among sickle cell patients hospitalized at the Muhimbili National Hospital.

Methods

This is an ongoing, descriptive, cross-sectional, hospital-based study among individuals with SCD, admitted to the Muhimbili National Hospital in Dares Salaam, Tanzania. A minimum sample size of 369 was calculated based on the previous prevalence of hospitalizations due to severe anemia (20%) in the same cohort. We are using a piloted standardized case report form to document clinical and laboratory parameters following informed consent. Data analysis will be performed using Stata software. Severe anemia is defined as Hb<5g/dL. Chi-square or Fisher’s exact test will be used to ascertain association between categorical variables, and t-test will be used for numerical variables. Regression models for severe anemia against explanatory and confounding variables will be run, and results will be presented as adjusted odds ratio with 95% confidence intervals. A P value of <.05 will be considered significant.

Results

Enrolment commenced in January 2015 and concluded in September 2016. Complete data analysis will begin in February 2018. The study results are expected to be published in May 2018.

Conclusions

This protocol paper will provide a useful and practical model for conducting cross-sectional studies in hospitalized patients that cover a wide ranging of clinical and laboratory variables.

[French guidelines for the management of adult sickle cell disease: 2015 update]

Sickle cell disease is a systemic genetic disorder, causing many functional and tissular modifications. As the prevalence of patients with sickle cell disease increases gradually in France, every physician can be potentially involved in the care of these patients. Complications of sickle cell disease can be acute and chronic. Pain is the main symptom and should be treated quickly and aggressively. In order to reduce the fatality rate associated with acute chest syndrome, it must be detected and treated early. Chronic complications are one of the main concerns in adults and should be identified as early as possible in order to prevent end organ damage. Many organs can be involved, including bones, kidneys, eyes, lungs, etc. The indications for a specific treatment (blood transfusion or hydroxyurea) should be regularly discussed. Coordinated health care should be carefully organized to allow a regular follow-up near the living place and access to specialized departments. We present in this article the French guidelines for the sickle cell disease management in adulthood.

Improving outcomes in children with sickle cell disease: treatment considerations and strategies

Over the past decades there has been a significant improvement in the care of patients with sickle cell disease (SCD) in high-income countries. However, more needs to be learned about the complex pathophysiology and the factors that contribute to the development of end organ damage from the disease. While antibiotic prophylaxis and appropriate treatment of infections have resulted in a significant reduction of early mortality, management of the painful episodes and prevention of organ damage remain a challenge. Hydroxyurea is the only medication approved as disease-modifying therapy, and bone marrow transplant as curative treatment is not available to most patients. In low-income countries with the highest disease burden, early mortality is high due to limited resources for systematic screening, early diagnosis, and disease management. In order to improve outcomes in patients with SCD in high-income countries, better and widespread implementation of known disease-modifying therapies and the development of newer therapies targeting key pathophysiologic pathways are required. In low-income countries with high disease burden, innovative approaches to develop low-cost diagnostic devices and treatments that can be implemented to scale are needed to combat early mortality from the disease. Sustainable solutions in low-resource settings require evidence-based affordable interventions that can be integrated into primary and secondary healthcare systems.

Trends in blood transfusion among hospitalized children with sickle cell disease

BACKGROUND

Blood transfusions represent a major therapeutic option in acute management of sickle cell disease (SCD). Few data exist documenting trends in transfusion among children with SCD, particularly during hospitalization.

PROCEDURE

This was an analysis of cross-sectional data of hospital discharges within the Kid's Inpatient Database (years 1997, 2000, 2003, 2006, 2009). Hospitalizations for children (0-18 years) with a primary or secondary SCD-related diagnosis were examined. The primary outcome was blood transfusion. Trends in transfusion were assessed using weighted multivariate logistic regression in a merged dataset with year as the primary independent variable. Co-variables consisted of child and hospital characteristics. Multivariate logistic regression was conducted for 2009 data to assess child and hospital-level factors associated with transfusion.

RESULTS

From 1997 to 2009, the percentage of SCD-related hospitalizations with transfusion increased from 14.2% to 28.8% (P < 0.0001). Among all SCD-related hospitalizations, the odds of transfusion increased over 20% for each successive study interval. Hospitalizations with vaso-occlusive pain crisis (OR 1.35, 95% CI 1.27-1.43) or acute chest syndrome/pneumonia (OR 1.24, 95% CI 1.13-1.35) as the primary diagnoses had the highest odds of transfusion for each consecutive study interval. Older age and male gender were associated with higher odds of transfusion.

CONCLUSIONS

Blood transfusion is increasing over time among hospitalized children with SCD. Further study is warranted to identify indications contributing to the rise in transfusions and if transfusions in the inpatient setting have been used appropriately. Future studies should also assess the impact of rising trends on morbidity, mortality, and other health-related outcomes.

Alloimmunization in sickle cell anemia in the era of extended red cell typing

BACKGROUND

Red blood cell (RBC) transfusion remains an essential part of the management of patients with sickle cell disease (SCD). Alloimmunization is a major complication of transfusions. Extended RBC typing is advocated as a means to reduce alloimmunization in SCD. Our goal was to assess alloimmunization among individuals with SCD at our center since implementing extended RBC typing.

MATERIALS AND METHODS

We reviewed electronic medical records of all patients with SCD (N = 641) in our comprehensive SCD Program to determine transfusion histories. Cross-referencing with our blood bank database, we extracted data such as antibodies identified, detection date and genotyping in specific cases. Transfusion sources were determined for those with C, E, and Kell antibodies.

RESULTS

Of 180 patients transfused from 2002 to 2011, 26 developed at least one new antibody. The majority of alloimmunized patients (14/26) received episodic transfusions only. The most common antibodies formed were against C and E antigens. Of the 16 patients who developed C, E, Kell antibodies, nine had one or more documented transfusions at an outside hospital. Five patients had Rh variants undetectable on routine phenotyping including two novel e alleles related to ceAR and ce(S)(733G).

CONCLUSION

Despite extended RBC typing, alloimmunization may still occur due to RBC variants that are not detected on routine screening and transfusions at institutions where extended RBC typing is not done. Extended RBC typing should be the standard of care for patients with SCD. Prospective genotyping may reduce allosensitization to rare variants not detected on routine screening.

Indications and complications of transfusions in sickle cell disease

Red cell transfusion remains an important part of the management of acute and chronic complications in SCD. The ongoing and emerging uses of transfusions in SCD may have significant benefits; however, the potential complications of transfusions also deserve careful consideration. In this report we review current indications for transfusions, transfusion complications, modifications of transfusion practices to mitigate risk, and potential considerations to improve transfusion outcomes.

Relevance of RH variants in transfusion of sickle cell patients

Transfusion remains the main treatment of sickle cell disease patients. Red cell alloimmunization is frequent because of the antigen disparities between patients of African descent and donors of European ancestry. Alloimmunization is associated with severe hemolytic transfusion reaction, autoantibody formation, and difficulties in the management of transfusion compatibility. Beside common antigens, a number of different RH variant antigens found in individuals of African descent can be involved in alloimmunization. If some variants, such as Hr(S) negative antigens, are known to prone significant alloantibodies and delayed hemolytic transfusion reactions, it is not clear whether all the described variants represent a clinical risk for sickle cell disease patients. The knowledge of the clinical relevance of RH variants is a real issue. An abundance of molecular tools are developed to detect variants, but they do not distinguish those likely to prone immunization from those that are unlikely to prone immunization and delayed hemolytic transfusion reactions. A strategy of prevention, which generally requires rare red blood cells, cannot be implemented without this fundamental information. In this review, we discuss the relevance of RH variants in sickle cell disease, based on the published data and on our experience in transfusion of these patients.

Current strategies for the management of children with sickle cell disease

Children with sickle cell disease may present to doctors anywhere in the world. In developed countries, neonatal screening allows early identification and management of the disease, mostly through daily antibioprophylaxis, immunizations and education of the parents. Stroke prevention relies on the detection of high-risk patients by annual transcranial Doppler ultrasonography from 2 to 16 years of age. Annual check-ups aim to detect early organ deficiencies. The most frequent complications are pain, infections and acute anemia; they may occur in combination. Approximately 10% of children have severe sickle cell disease that may require chronic blood transfusion, hydroxyurea or hematopoietic stem cell transplantation. Comprehensive management programs have dramatically increased survival, and most patients now reach adulthood.

[Guidelines for management of adult sickle cell disease]

Sickle cell disease is a systemic disease that can potentially involve all organs. As the prevalence of patients with sickle cell disease increases gradually in France, every physician can be potentially involved in the care of these patients. Complications of sickle cell disease can be acute or chronic. Pain is the main symptom and should be treated quickly and aggressively. Acute chest syndrome is the leading cause of acute death and must be prevented, detected, and treated without delay. Chronic complications are one of the main concerns in adults and should be identified as early as possible in order to prevent sequels. Many organs can be involved, including the bones, kidneys, eyes, lungs... The indications for a specific treatment (blood transfusion or hydroxyurea) should be discussed. Health care should be carefully organized to allow both a regular follow-up near the living place and access to specialized departments. We present in this article the French guidelines for the sickle cell disease management in adulthood.

Blood component therapy

The blood component support in pediatric patients is more challenging as compared to adult patients, as such, a thorough understanding of various blood components and indications for each is critical when making the decision for transfusion. Transfusion needs in pediatric group parallel the changes that accompany the transitions from fetus to neonate, neonate to infant, and throughout childhood. Modified or unmodified blood components viz. red blood cells, platelets, granulocytes, fresh frozen plasma and cryoprecipitate are required for transfusion support in pediatric population. In general, fetuses and infants younger than 4 months of age have specialized transfusion requirements whereas transfusion of infants older than 4 months and children parallels those for adults. Transfusion practices differ widely among pediatric care units depending upon individual preferences, hospital transfusion policy and resource availability. There is a need to implement best transfusion practices and despite the lack of firm evidences, existing pediatric transfusion guidelines can help pediatric care providers in their decisions related to component transfusion.

Acute myocardial infarction in sickle cell disease: a systematic review

Myocardial infarction in young adults is, in practice, a diagnosis of exclusion. Given the fact that most of the patients with sickle cell disease are young and have predisposition to painful crisis, they are often overlooked for myocardial infarction. These patients often have few or no traditional risk factors for coronary artery disease, and risk stratification tools such as the Thrombolysis in Myocardial Infarction (TIMI) and Global Registry of Acute Coronary Events (GRACE) models place these patients at low risk. Nonspecific changes on electrocardiogram are of little diagnostic value. Myocardial infarction is very often a missed diagnosis in patients with sickle cell disease. Diagnostic criteria, potential mechanisms, and management for acute myocardial infarction in patients with sickle cell disease are discussed.

Disparity in the management of iron overload between patients with sickle cell disease and thalassemia who received transfusions

BACKGROUND

Transfusion therapy is frequently used to prevent morbidity in sickle cell disease (SCD), and subsequent iron overload is common. The objective of this study was to evaluate the current standard of care in monitoring iron overload and related complications in patients with SCD compared to thalassemia (Thal).

STUDY DESIGN AND METHODS

A cross-sectional study was conducted at 31 hematology clinics in the United States, Canada, or the United Kingdom. Patients who received transfusions with a mean serum ferritin level of least 2000 ng per mL were eligible. A total of 199 patients with SCD (113 female; 24.9 +/- 13.2 years) and 142 with Thal (66 female; 25.8 +/- 8.1 years) were recruited, and data were collected between 2001 and 2003 by interview and medical record review.

RESULTS

Although both groups were recruited on the basis of significant iron overload, the likelihood of performing a liver biopsy for routine iron monitoring was significantly higher (odds ratio [OR], 3.4; 95% confidence interval [CI], 2.2-5.3) in Thal than SCD. Thal patients were also more likely to be screened for iron-related organ injury including an echocardiograph for cardiomyopathy (OR, 2.6; p < 0.001; 95% CI, 1.6-4.2), alanine aminotransferase for liver function (OR, 8.3; CI, 1.05-64.4), and thyroid-stimulating hormone for hypothyroidism (OR, 12.3; CI, 7.0-21.5). For adult SCD patients, those maintained on simple transfusion with a serum ferritin level of greater than 2500 ng per mL were the least likely to have a liver biopsy (p < 0.03).

CONCLUSIONS

These data highlight the unsystematic monitoring of iron and related organ injury in SCD. Until the relationship between iron and related comorbidities is better understood, routine monitoring of iron overload in SCD patients who receive transfusions should be considered a standard part of clinical care.

Morbidity and mortality in chronically transfused subjects with thalassemia and sickle cell disease: A report from the multi-center study of iron overload

A natural history study was conducted in 142 Thalassemic (Thal), 199 transfused Sickle Cell Disease (Tx-SCD, n = 199), and 64 non-Tx-SCD subjects to describe the frequency of iron-related morbidity and mortality. Subjects recruited from 31 centers in the US, Canada or the UK were similar with respect to age (overall: 25 +/- 11 years, mean +/- SD) and gender (52% female). We found that Tx-SCD subjects were hospitalized more frequently compared with Thal or non-Tx-SCD (P < 0.001). Among those hospitalized, Tx-SCD adult subjects were more likely to be unemployed compared with Thal (RR = 1.6, 95% CI 1.0-2.5) or non-Tx-SCD (RR = 3.1, 95% CI 1.3-7.3). There was a positive relationship between the severity of iron overload, assessed by serum ferritin, and the frequency of hospitalizations (r= 0.20; P = 0.009). Twenty-three deaths were reported (6 Thal, 17 Tx-SCD) in 23.5 +/- 10 months of follow-up. Within the Tx-SCD group, those who died began transfusion (25.3 vs. 12.4 years, P < 0.001) and chelation therapy later (26.8 vs. 14.2 years, P = 0.01) compared with those who survived. The unadjusted death rate in Thal was lower (2.2/100 person years) compared with that in Tx-SCD (7.0/100 person years; RR = 0.38: 95% CI 0.12-0.99). However, no difference was observed when age at death was considered. Despite improvements in therapy, death rate in this contemporary sample of transfused adult subjects with Thal or SCD is 3 times greater than the general US population. Long term follow-up of this unique cohort of subjects will be helpful in further defining the relationship of chronic, heavy iron overload to morbidity and mortality.

Etiology of strokes in children with sickle cell anemia

The most devastating complication of sickle cell anemia is cerebral infarction, affecting approximately 30% of all individuals with sickle cell anemia. Despite being one of the most common causes of stroke in infants and children, the mechanism of cerebral infarction in this population has not been extensively studied and is poorly understood. Multiple, synergistic factors are important in the pathogenesis of stroke including the hemodynamic effects of cerebral arterial occlusive disease, viscosity, chronic and acute anemia and acute medical events. This review focuses on the relationship between these factors in order to provide a foundation for further study of the etiology of strokes in this high-risk population.

Guidelines on the use of therapeutic apheresis in clinical practice—Evidence-based approach from the apheresis applications committee of the American society for apheresis

The American Society for Apheresis (ASFA) Apheresis Applications Committee is charged with a review and categorization of indications for therapeutic apheresis. This elaborate process had been undertaken every 7 years resulting in three prior publications in 1986, 1993, and 2000 of "The ASFA Special Issues." This article is the integral part of the Fourth ASFA Special Issue. The Fourth ASFA Special Issue is significantly modified in comparison to the previous editions. A new concept of a fact sheet has been introduced. The fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis. A detailed description of the fact sheet is provided. The article consists of 53 fact sheets devoted to each disease entity currently categorized by the ASFA. Categories I, II, and III are defined as previously in the Third Special Issue. However, a few new therapeutic apheresis modalities, not yet approved in the United States or are currently in clinical trials, have been assigned category P (pending) by the ASFA Clinical Categories Subcommittee. The diseases assigned to category IV are discussed in a separate article in this issue.

Investigational agents for sickle cell disease

Developments in the treatment of sickle cell disease (SCD) have not kept pace with advances in understanding the pathophysiology of this haemoglobinopathy. Drugs undergoing preclinical and clinical assessment for the therapy of these globin gene disorders are discussed in this article. Beginning with investigational agents for treatment of SCD as a whole, the discussion proceeds to drugs being developed for specific manifestations or iatrogenic complications. Despite being licensed in the USA, the prototype antisickling agent, hydroxycarbamide, has not attained worldwide clinical use because of concerns about long-term toxicity. The less toxic decitabine, which (as with hydroxycarbamide) increases fetal haemoglobin level, cannot be administered orally; therefore, the search continues for effective and safe antisickling drugs that can be taken orally. The naturally occurring benzaldehyde 5-hydroxymethyl-2-furfural has shown promising antisickling properties in vitro, and when administered to transgenic sickle mice. These effects are surpassed by the new synthetic pyridyl derivatives of benzaldehyde. Studies in humans with SCD are required to assess the clinical efficacy of these benzaldehydes. Niprisan, another antisickling agent with significant clinical efficacy and an attractive safety profile, is undergoing further development. The prospects of antiadhesion therapy in SCD are demonstrated by a recombinant protein containing the Fc fragment of IgG fused to the natural ligand for selectins: the conjugate significantly inhibited blood vessel occlusion in transgenic sickle mice. Whereas the orally administrable iron-chelating agent deferasirox is likely to increasingly take the place of desferioxamine (which can only be given parenterally), effective treatment of priapism in SCD remains a distressing challenge.

Surgery in sickle cell disease

Persons with sickle cell disease (SCD) are more likely to undergo surgery than are the general population during their lifetime. For example, cholecystectomy as a consequence of gallstones is more frequent in persons with SCD, as is hip arthroplasty in younger people as a result of avascular necrosis of the femoral head. Because surgery exposes patients to many of the factors that are known to precipitate red blood cell sickling, persons with SCD undergoing surgery require meticulous clinical care to prevent perioperative sickle cell-related complications. Even with meticulous care, approximately 25% to 30% of patients will have a postoperative complication. This article provides readers with information about the role of surgery in SCD and the measures that should be taken to ensure patients are well cared for in the perioperative period.

New therapies for sickle cell disease

New and developing therapeutic agents for the treatment of sickle cell disease include hydroxyurea (an unlicensed experimental drug in most countries), omega-3 fatty acids, and the Gardos channel inhibitor ICA-17043. Anti-cellular adhesion therapy has considerable prospects; however, it has yet to be translated into clinical practice. For specific disease manifestations, pulmonary hypertension responds well to oral arginine, l-carnitine, and exchange blood transfusion therapy alone or in combination with other agents. Primary stroke prevention with transfusion therapy is now considered standard care. Oral iron chelators are administered increasingly instead of the more inconvenient parenteral desferrioxamine. Deferiprone is licensed in Europe and India, and deferasirox (ICL670) holds out important promise because it has not been shown to affect blood cell counts.

Exhaled carbon monoxide levels in children with sickle cell disease

It is important to measure the rate of haemolysis in patients with sickle cell disease (SCD) to identify aplastic crises and indirectly assess the rate of vaso-occlusion and sequestration. The aim of this study was to assess whether end-tidal carbon monoxide (ETCOc) levels in children with sickle cell disease (SCD) could be measured reproducibly, reflected haemolysis and whether they were elevated compared to those of similarly aged, ethnic matched children without SCD (controls). ETCOc levels were measured non-invasively in 87 SCD children (age range 2.3-17.6 years) and 26 age and ethnic origin matched healthy controls using an electro-chemical sensor. The within- and between- occasion reproducibilities were assessed in ten and 15 SCD children respectively. ETCOc levels of 15 SCD children undergoing regular transfusions were related to carboxyhaemoglobin, haemoglobin and bilirubin levels. The within and between occasions' mean intrasubject coefficients of reproducibility were 5% and 18% respectively. Positive correlations were found between the ETCOc and carboxyhaemoglobin ( P =0.007) and bilirubin ( P =0.02) levels, and a significant negative correlation between the ETCOc and haemoglobin ( P =0.0002) levels. The mean and SD ETCOc levels of the SCD children (4.9 ppm; SD 1.7 ppm) were significantly higher than that of the controls (mean 1.3 ppm; SD 0.4 ppm) (difference between means 3.60; 95% C.I. 2.93-4.28; P <0.0001).

CONCLUSION

These results suggest that measurement of end-tidal carbon monoxide levels is a reliable and useful method to monitor haemolysis in children with sickle cell disease.

Acute Chest Syndrome: the role of erythro-exchange in patients with sickle cell disease in Sicily

Acute Chest Syndrome (ACS) describes a syndrome characterized by the presence of a new pulmonary infiltrate on a chest X-ray, fever, and respiratory symptoms and is the leading cause of death and hospitalization in sickle cell disease (SCD). We studied 21 patients affected by SCD (13 HbSbeta+, 4 HbS beta(o), 4 HbSS, mean age 38.2 years). Six out of the 21 patients developed one episode of ACS (two patients had positive blood cultures, for Mycoplasma pneumoniae and Haemophilus influenzae respectively). The aim of our study was to evaluate the therapeutic efficacy of red cell-exchange during ACS. This procedure decreases HbS levels. The patients who underwent erythro-exchange showed a dramatic clinical and radiographic improvement with stabilized HbS levels between 20% and 30%. During follow up (14-32 months), none of the 6 patients developed viral complications related to transfusion therapy, alloimmunization or recurrence of ACS. In conclusion, in regard to the pre- and post-red cell-exchange clinical and laboratory data, we can say that red cell-exchange provides a dramatic resolution of the episode of ACS, minimizes the development of iron overload, and rapidly decreases HbS and hematocrit levels. In light of our results, we hypothesize that ACS episodes are secondary to pulmonary damage and to a gradual worsening related to age, and that there is some evidence that individuals affected by SCD in the third to fourth decade of life are more susceptible to ACS and/or other severe disease-related complications, needing repeated and strict clinical follow up.

The comprehensiveness care of sickle cell disease

Millions of people across the world have sickle cell disease (SCD). Although the true prevalence of SCD in Europe is not certain, London (UK) alone had an estimated 9000 people with the disorder in 1997. People affected by SCD are best managed by a multidisciplinary team of professionals who deliver comprehensive care: a model of healthcare based on interaction of medical and non-medical services with the affected persons. The components of comprehensive care include patient/parent information, genetic counselling, social services, prevention of infections, dietary advice and supplementation, psychotherapy, renal and other specialist medical care, maternal and child health, orthopaedic and general surgery, pain control, physiotherapy, dental and eye care, drug dependency services and specialist sickle cell nursing. The traditional role of haematologists remains to co-ordinate overall management and liase with other specialities as necessary. Co-operation from the affected persons is indispensable to the delivery of comprehensive care. Working in partnership with the hospital or community health service administration and voluntary agencies enhances the success of the multidisciplinary team. Holistic care improves the quality of life of people affected by SCD, and reduces the number as well as length of hospital admissions. Disease-related morbidity is reduced by early detection and treatment of chronic complications. Comprehensive care promotes awareness of SCD among affected persons who are encouraged to take greater control of their own lives, and achieves better patient management than the solo efforts of any single group of professionals. This cost-effective model of care is an option for taking haemoglobinopathy services forward in the new millennium.

Secondary iron overload

Transfusion therapy for inherited anemias and acquired refractory anemias both improves the quality of life and prolongs survival. A consequence of chronic transfusion therapy is secondary iron overload, which adversely affects the function of the heart, the liver and other organs. This session will review the use of iron chelating agents in the management of transfusion-induced secondary iron overload. In Section I Dr. John Porter describes techniques for the administration of deferoxamine that exploit the pharmacokinetic properties of the drug and minimize potential toxic side effects. The experience with chelation therapy in patients with thalassemia and sickle cell disease will be reviewed and guidelines will be suggested for chelation therapy of chronically transfused adults with refractory anemias. In Section II Dr. Nancy Olivieri examines the clinical consequences of transfusion-induced secondary iron overload and suggests criteria useful in determining the optimal timing of the initiation of chelation therapy. Finally, Dr. Olivieri discusses the clinical trials evaluating orally administered iron chelators.