Acute Hemolytic Crisis Research Articles

Acute Chest Syndrome In A Patient With Sickle Cell Anemia Successfully Treated With Erythrocytapheresis

Acute chest syndrome is a serious complication and one of the causes of mortality in sickle cell disease. Seventeen years-old male was admitted to hematology clinic with acute chest pain and hemolytic crisis. He was treated with intravenous fluid and nasal oxygen supplementation. Chest pain was sustained and brain confusion with severe hypoxemia developed after 12 hours of hospitalization. The patient was transferred suddenly to intensive care unit of our hospital. Endotracheal intubation and mechanical ventilation was initiated. In spite of respiratory and medical support, his medical status worsened, so red cell exchange transfusion was made. Brain functions, other vital parameters, and organ functions were turned to normal after treatment. We conclude that the physician should be alert if the patient with sickle cell disease being hypoxic and we believe that red cell exchange transfusion is effective treatment modality in these patients.

Acute haemolytic crisis in a Thai patient with homozygous haemoglobin Constant Spring (Hb CS/CS): a case report

Acute haemolysis associated with mild upper respiratory tract infection was observed in a Thai boy who presented with a rapid decline in haemoglobin (Hb) levels, haemoglobinuria and evidence of intravascular haemolysis. Several possible causes giving rise to such a condition were excluded including G6PD deficiency, which is extremely common in Thailand. Subsequent haematological and molecular analyses demonstrated that the patient was homozygous for Hb Constant Spring (Hb CS/CS), an a globin haemoglobinopathy. It has been shown previously that patients with homozygous Hb CS had mild haemolytic anaemia secondary to an accumulation of alpha(CS) chains, which are toxic to red blood cell membrane cytoskeletons. Increased body temperature might induce more precipitation of this a globin variant. This report highlights the importance of Hb CS/CS as a potential predisposing cause of acute haemolysis in children that might be aggravated by acute bacterial or viral infections. This is particularly relevant for patients of Southeast Asian descent where this abnormal haemoglobin is highly prevalent.

The use of ultrapurified bovine hemoglobin solution in the treatment of two cases of presumed red maple toxicosis in a miniature horse and a pony

AbstractObjective: To report the use of ultrapurified bovine hemoglobin (PBHg) in the treatment of red maple toxicosis in horses.Summary: The use of PBHg in a miniature horse and a pony with clinical signs of red maple toxicosis is described. Initial treatment of the horses included blood transfusion in Case 1, and intravenous crystalloid fluids, nasogastrically administered mineral oil, and activated charcoal in both cases. Both cases received PBHg (16 and 11 ml/kg, respectively) when the hematocrit dropped below 10%. Clinical stabilization of the horses (reflected by improved vital signs and mucous membrane color, increase in PvO2, and increase in plasma hemoglobin) was temporary, lasting 12 and 42 hours, respectively. A whole blood transfusion was given 16 hours after the infusion of PBHg in Case 1 and 42 hours after the infusion of PBHg in Case 2. The horses were discharged on days 15 and 17, respectively. Both were stable on discharge and were reported to be doing well 1 month after discharge. New information provided: Ultrapurified bovine hemoglobin is shown to be safe in the treatment of red maple toxicosis. Ultrapurified bovine hemoglobin infusion resulted in temporary improvement in oxygen (O2) delivery as assessed by clinical and laboratory parameters. The use of PBHg may provide an ‘oxygen bridge’ in an acute hemolytic crisis in the horse. It may allow additional time in the treatment of red maple toxicity for the acute hemolysis to subside and for metabolism of the toxin to occur, thus providing a more optimal environment for an effective whole blood transfusion.

Intoxicação espontânea por Senecio brasiliensis (Asteraceae) em ovinos no Rio Grande do Sul

Descreve-se a ocorrência de um surto de intoxicação espontânea por Senecio brasiliensis em ovinos em um estabelecimento do município de Mata, Estado do Rio Grande do Sul, em meados de janeiro de 1997. De um total de 94 ovinos, 51 (54,25%) animais adoeceram e 50 (53,2%) morreram. Esse rebanho permaneceu durante aproximadamente 7 meses (de junho de 1996 a janeiro de 1997) em piquetes de pastagem nativa onde havia grande quantidade de S. brasiliensis. O quadro clínico manifestado pelos animais afetados consistia em fotossensibilização, emagrecimento progressivo, apatia, fraqueza, perturbações neurológicas como depressão, andar a esmo e desequilibrado, icterícia e hemoglobinúria. Houve melhora das lesões de pele naqueles ovinos que desenvolveram fotossensibilização hepatógena depois que foram retirados do sol. As principais lesões macroscópicas observadas em 9 dos 10 ovinos necropsiados incluíam fígado diminuído de tamanho, firme, difusamente marrom amarelado ou esverdeado, com quantidades variáveis de nódulos de 1-3 mm de diâmetro, bem circunscritos, salientes na cápsula, amarelados, distribuídos aleatoriamente por todo o parênquima. A vesícula biliar estava repleta e preenchida por bile verde escura e espessa. Havia também derrames cavitários (hidropericárdio e ascite). Crise hemolítica aguda fatal associada à intoxicação crônica hepatógena por cobre foi observada em cinco ovinos. Além das lesões hepáticas macroscópicas já mencionadas, foi observada icterícia generalizada da carcaça, rins tumefeitos, friáveis, difusamente escurecidos ou com fino pontilhado enegrecido; a urina era marrom escura (hemoglobinúria). As principais lesões microscópicas foram observadas no fígado e consistiam em hepatomegalocitose, proliferação de ductos biliares (hiperplasia ductal) e fibrose periportal moderada acompanhada de infiltrado inflamatório mononuclear. Macrófagos carregados de pigmento acastanhado formavam aglomerados nas tríades portais ou estavam dispersos entre os hepatócitos remanescentes. O material armazenado no citoplasma desses macrófagos correspondia a ceróide e cobre, positivo nas técnicas de PAS e rodanina, respectivamente. Nos rins de cinco animais, havia nefrose hemoglobinúrica caracterizada por degeneração e necrose do epitélio tubular, presença de hemoglobina e hemossiderina no citoplasma das células epiteliais dos túbulos contorcidos e cilindros de hemoglobina na luz tubular. Evidência morfológica de encefalopatia hepática incluía degeneração esponjosa (status spongiosus) da substância branca do encéfalo. Achados ultra-estruturais no fígado incluíam graus variáveis de degeneração hepatocelular caracterizada pelo acúmulo de numerosas gotas lipídicas no citoplasma das células hepáticas e presença de lisossomos carregados de material eletrodenso que, na maioria dos casos, correspondia à lipofuscina-ceróide. Adicionalmente, havia discreta dilatação do retículo endoplasmático rugoso e moderada hiperplasia do retículo endoplasmático liso em algumas regiões do citoplasma dos hepatócitos. No epitélio dos túbulos contorcidos proximais do rim foi observado edema intracelular e diversas alterações mitocondriais de caráter degenerativo que incluíam tumefação, desorganização e ruptura das cristas, matriz finamente granular, acúmulo de gotículas de gordura e ruptura das membranas em alguns casos. Lisossomos contendo material fortemente eletrodenso foram observados em muitas células tubulares renais. O exame laboratorial de fragmentos de fígado e rim dos ovinos afetados revelou níveis elevados de cobre que variaram respectivamente de 369 ppm a 1248 ppm e 152 ppm a 687 ppm com base na matéria seca. O diagnóstico de intoxicação por Senecio brasiliensis baseou-se em dados epidemiológicos, clínicos, de necropsia, histopatológicos e laboratoriais.

Acute Hemolytic Crises in Patients with G6PD Deficiency: A Case Series

Acute Hemolytic Crises in Patients with G6PD Deficiency: A Case Series

Labor analgesia in a patient with paroxysmal nocturnal hemoglobinuria with thrombocytopenia

Background and Objectives: Paroxysmal nocturnal hemoglobinuria (PNH) is a form of acquired hemolytic anemia in which a defect of glycophosphoinositol anchor proteins in the cell membrane of bone marrow stem cells leads to activation of the complement system and consequent destruction of defective cells. The characteristics of this disease are an increased frequency of thrombotic events, anemia, and thrombocytopenia. Methods: We report a case of a pregnant patient with PNH with thrombocytopenia who delivered vaginally after receiving epidural labor analgesia. Prophylaxis of thromboembolism was performed with heparin 1 hour after the removal of the epidural catheter, and repeated at 12-hour intervals. Sensory changes or motor changes and pain were monitored every 10 minutes for 8 hours after delivery. Results: During analgesia, the patient reported complete pain relief. Delivery and the immediate postpartum period were without any untoward events. Conclusions: Four major factors influenced the anesthetic conduct used for the present patient: (1) the risk of an acute hemolytic crisis, (2) the need to perform prophylaxis for thromboembolism, (3) the need to reduce labor stress, and (4) minimizing the risk of missing an epidural hematoma. We also present a survey of the literature about PNH and discuss the anesthetic conduct in this patient. Reg Anesth Pain Med 2001;26:79-82.

Glucose-6-Phosphate Dehydrogenase Deficiency: A Worldwide Potential Cause of Severe Neonatal Hyperbilirubinemia

After completing this article, readers should be able to: 1. Explain methods of preventing the hyperbilirubinemia caused by glucose-6-phosphate dehydrogenase (G6PD) deficiency. 2. Compare and contrast the correlation between hemolysis and serum bilirubin levels in healthy infants and those who are G6PD-deficient. 3. Describe the role of deficient bilirubin conjugation in the pathogenesis of G6PD deficiency-associated neonatal hyperbilirubinemia. 4. Define the risk for neonatal hyperbilirubinemia in female G6PD-deficient heterozygotes, G6PD-deficient homozygotes, and hemizygote males. Glucose-6-phosphate dehydrogenase (G6PD) deficiency, a commonly occurring X-linked genetic enzyme defect, is notorious for its association with acute hemolytic crises occurring in response to a frequently identifiable trigger (favism). Another potentially devastating danger of this condition is severe neonatal hyperbilirubinemia with its accompanying bilirubin encephalopathy, kernicterus, and death. Far from being a condition limited to historical time epochs and developing countries, G6PD deficiency-associated kernicterus still is seen in modern times. Indeed, among 80 infants from 21 states in the United States documented in a pilot Kernicterus Registry between 1984 and 1998, 18 (22.5%) were reported to have G6PD deficiency. Furthermore, Maisels recently listed G6PD deficiency among the 10 factors that are associated most commonly with an increased risk of nonhemolytic jaundice. Because of the association with favism, G6PD-associated hyperbilirubinemia traditionally has been regarded as hemolytic in origin. However, recent research has shown that although acute hemolysis does play a role, its contribution in many cases may be smaller than previously thought. The emphasis now has been placed on decreased bilirubin conjugation, with promoter polymorphism for the gene for the bilirubin conjugating enzyme, UDP glucuronoslytransferase 1A1 (UGT1A1), being a major factor in production of the icterus. In this review we highlight key aspects of the pathogenesis of this type of hyperbilirubinemia, explain the relevance of the condition, and describe a particularly problematic group that has a recently recognized high incidence of …

Effect of Desferrioxamine in Acute Haemolytic Anaemia of Glucose-6-Phosphate Dehydrogenase Deficiency

The effectiveness of desferrioxamine (DFO) in ameliorating the severity of the acute haemolysis of glucose-6-phosphate dehydrogenase (G6PD) deficiency was studied in 167 children with G6PD deficiency during an acute haemolytic crisis. All patients received packed cell transfusion on admission if their Hb levels were <8 g/dl, which was repeated as needed. Eighty patients also received a single dose of DFO 30–40 mg/kg by slow intravenous infusion (DFO group). The remaining 87 children did not receive DFO (control group). The need for more than one transfusion was less frequent in the DFO group as compared to the control group (p = 0.01). The need for late transfusion (transfusion after 36 h of admission) was also less in the DFO group (7%) compared to 21% in the control group (p = 0.02). On average, children in the DFO group needed less packed red blood cells (16.5 ml/kg body weight) than the control group (22.8 ml/kg body weight) and the difference was highly significant (p = 0.0001). We conclude from this study that DFO in a small dose is effective in the treatment of acute haemolytic crises of G6PD deficiency. It shortens the duration of the crisis and decreases the amount of blood transfusion needed.

Bilirubin levels in the acute hemolytic crisis of G6PD deficiency are related to Gilbert's syndrome

In this study we analyzed the effect of the (TA)7 polymorphism of the UGT1A gene associated with Gilbert's syndrome in G6PD-deficient subjects during an acute hemolytic crisis (fabic crisis). DNA from 44 subjects originating from the same geographic area in Sardinia was analyzed for the UGT1A promoter polymorphism. The increase of unconjugated bilirubin level during fabic crisis and its relationship with UGT1A polymorphism was evaluated. The UGT1A (TA)7 TATA box variant was found in 9/44 (21%) of the G6PD deficient subjects examined. The median value for unit of increase of bilirubin (mg/dl)/unit of decrease of hemoglobin (g/dl) was higher in variant homozygous than in heterozygous and normal subjects. These findings imply a contribution of the UGT1A polymorphism associated to Gilbert's syndrome to development of the hyperbilirubinemia in G6PD deficient subjects during acute hemolytic anemia.

Bilirubin Levels in The Acute Hemolytic Crisis of G6PD Deficiency are Related to Gilberts Syndrome

Bilirubin Levels in The Acute Hemolytic Crisis of G6PD Deficiency are Related to Gilberts Syndrome

Detection of enzootic babesiosis in baboons (Papio cynocephalus) and phylogenetic evidence supporting synonymy of the genera Entopolypoides and Babesia.

Blood smear evaluation of two baboons (Papio cynocephalus) experiencing acute hemolytic crises following experimental stem cell transplantation revealed numerous intraerythrocytic organisms typical of the genus Babesia. Both animals had received whole-blood transfusions from two baboon donors, one of which was subsequently found to display rare trophozoites of Entopolypoides macaci. An investigation was then undertaken to determine the prevalence of hematozoa in baboons held in our primate colony and to determine the relationship, if any, between the involved species. Analysis of thick and thin blood films from 65 healthy baboons (23 originating from our breeding facility, 26 originating from an out-of-state breeding facility, and 16 imported from Africa) for hematozoa revealed rare E. macaci parasites in 31%, with respective prevalences of 39, 35, and 12%. Phylogenetic analysis of nuclear small-subunit rRNA gene sequences amplified from peripheral blood of a baboon chronically infected with E. macaci demonstrated this parasite to be most closely related to Babesia microti (97.9% sequence similarity); sera from infected animals did not react in indirect fluorescent-antibody tests with Babesia microti antigen, however, suggesting that they represent different species. These results support an emerging view that the genus Entopolypoides Mayer 1933 is synonymous with that of the genus Babesia Starcovici 1893 and that the morphological variation noted among intracellular forms is a function of alteration in host immune status. The presence of an underrecognized, but highly enzootic, Babesia sp. in baboons may result in substantial, unanticipated impact on research programs. The similarity of this parasite to the known human pathogen B. microti may also pose risks to humans undergoing xenotransplantation, mandating effective screening of donor animals.

EFFECT OF HYDROXYUREA IN SICKLE CELL ANEMIA: A Clinical Trial in Children and Teenagers with Severe Sickle Cell Anemia and Sickle Cell beta-Thalassemia

This study evaluated the efficacy of hydroxyurea treatment in the prevention of vaso-occlusive crises among children and teenagers with severe sickle cell anemia and sickle cell beta-thalassemia. Nineteen children and young adults with severe sickle cell disease were enrolled to the hydroxyurea treatment trial. The incidence of vaso-occlusive crises, acute chest syndrome, hemolytic crises, splenic sequestration episodes, blood transfusions,and hospital days in the 2 years before hydroxyurea (HU) treatment were compared with the same parameters in the first 2 years of treatment. The patients received a mean dose of 21.3 mg/kg/day daily and were treated during a mean period of 40.3 14 months (range 20 to 68 months). Significant increases were observed after 1 month in the Hgb, MCV, MCH, and MCHC levels and were more notable after 3 months. The increase in the Hgb F level became important after 3 months of HU therapy and was highly significant (p < .001) beyond 6 months. No differences were observed in the R DW, reticulocyte count, Hgb S, and Hgb A2 . Severe neutropenia was observed in one case. A decrease in the frequency of vaso-occlusive crises, acute chest syndrome, hemolytic crises, blood transfusions, and days spent in the hospital was demonstrated during the HU treatment period compared to the same period before. The clinical and laboratory response to HU was dramatic in severely affected sickle cell anemia (SCA) patients. The response to HU in children and teenagers with severe sickle cell anemia is similar to the response in adults, and no severe adverse effects were observed.

Severe Neonatal Hyperbilirubinemia: A Potential Complication of Glucose-6-Phosphate Dehydrogenase Deficiency

G-6-PD deficiency is frequently associated with neonatal hyperbilirubinemia, which may be severe enough to cause kernicterus and death. Because of its association with acute trigger-induced hemolytic crises, G-6-PD deficiency-associated neonatal hyperbilirubinemia has been labelled as hemolytic in origin. In this article, the authors summarize recent evidence demonstrating that hemolysis cannot in and of itself be responsible for jaundice and that decreased bilirubin elimination plays a major role in its pathogenesis.

Index of Suspicion

Index of Suspicion

Capillary electrohoretic determination of purine nucleoside phosphorylase activity in human erythrocytes

Favism is an acute hemolytic anemia triggered by ingestion of fave beans in genetically susceptible subjects with severe deficiency of glucose-6-phosphate dehydrogenase (G6PD) activity. Erythrocytes from 10 favic patients had constantly and markedly increased calcium levels, as compared with values detected in 4 asymptomatic G6PD-deficient controls. Correspondingly, the calcium permeability of erythrocytes, estimated as the fraction of intracellular calcium exchangeable with externally added 45Ca2+, was invariably enhanced in favism and returned to normal patterns after several months from the acute hemolytic crisis. In favic patients, the levels of erythrocyte calcium ATPase activities showed wide variability, ranging from 2.0–12.9 μmol Pi/ml RBC/h, while control values in asymptomatic G6PD-deficient subjects were 10.62 ± 2.03 μmol Pi/ml RBC/h. Analysis of the calcium ATPase in situ in erythrocyte membranes from favic patients showed the same molecular mass of 134 kD as observed in the control subjects. Exposure of G6PD-deficient erythrocytes in vitro to autoxidizing divicine, a pyrimidine aglycone strongly implicated in the pathogenesis of favism which leads to late accumulation of intracellular calcium, caused: (i) a marked inactivation of calcium ATPase, without changes in the molecular mass of 134 kD; and (ii) the concomitant loss of spectrin, band 3 and band 4.1, all known substrates of the calcium activated procalpain-calpain proteolytic system. Thus, the increased intraerythrocytic calcium apparently results in the degradation of calcium ATPase observed in some favic patients. It is proposed that both enhanced calcium permeability and a calcium-stimulated degradation of the calcium pump are the mechanisms responsible for the perturbation of erythrocyte calcium homeostasis in favism.

Molecular Analysis of Glucose Phosphate Isomerase Deficiency Associated With Hereditary Hemolytic Anemia

We report here two new cases of glucose phosphate isomerase (GPI) deficiency associated with hemolytic anemia and present the results of molecular analysis of the five Japanese GPI variants. A Japanese girl (GPI Fukuoka) had an episode of prolonged neonatal jaundice and at 3 years of age was admitted due to acute hemolytic crisis occurring with upper respiratory tract infection. Red blood cell (RBC) GPI activity was decreased to 11.8% of normal and the reduced glutathione (GSH) level of RBCs was slightly decreased. A 54-year-old Japanese man (GPI Iwate) was hospitalized due to chronic active hepatitis, and compensated hemolysis was noted. RBC GPI activity of the proband was decreased to 18.8%, and the GSH content was about half of the normal mean value. Sequencing of the reticulocyte GPIcDNA showed homozygous missense mutations 1028CAG-->CGG (343Gln-->Arg), 14ACC-->A7C (5Thr-->lle), 671ACG-->A7G (224Thr-->Met), and 1615GAC-->AAC (539Asp-->Asn) in GPI Narita, GPI Matsumoto, GPI Iwate, and GPI Fukuoka, respectively. We also identified GPI Kinki as a compound heterozygote of 1124ACA-->AGA(375Thr-->Arg)/ 1615GAC-->AAC(539Asp-->Asn). Our findings, together with the previous results of other investigators, showed that the GPI gene mutations so far identified were heterogeneous, although most GPI variants had common biochemical characteristics such as heat instability and normal kinetics. Several amino acid substitutions were identified in the proximity of the catalytically important amino acid residues such as Ser/Asp 159/160, Asp341, and Lys518, which have been identified in the structural analysis of the pig GPI. The molecular characterization of human GPI variants, therefore, may provide new insights into the genotype-phenotype correlation of GPI deficiency as well as the structure-function relationship of this enzyme.

Chemical analysis and hemolytic activity of the fava bean aglycon divicine.

Divicine is an unstable aglycon metabolite of the fava bean pyrimidine beta-glucoside vicine. Divicine has long been thought to be a mediator of an acute hemolytic crisis, known as favism, in susceptible individuals who ingest fava beans (Vicia faba). However, a recent report has questioned the chemical identity of the divicine that was used in most of the studies on divicine hemotoxicity. The present study was undertaken to examine the hemolytic potential of synthetic divicine. Divicine was synthesized and its identity and purity were confirmed by HPLC, mass spectrometry, and NMR spectroscopy. The stability and redox behavior of divicine, under physiological conditions, were examined by HPLC and cyclic voltammetry. The data indicate that divicine is readily oxidized under aerobic conditions; however, it was sufficiently stable at pH 7.4 to permit its experimental manipulation. When 51Cr-labeled rat erythrocytes were exposed in vitro to the parent glucoside, vicine (5 mM), and then readministered to rats, no decrease in erythrocyte survival was observed. In contrast, erythrocyte survival was dramatically reduced by in vitro exposure to divicine (1.5 mM). These data demonstrate that divicine is a direct-acting hemolytic agent and thus may be a mediator of the hemolytic crisis induced by fava bean ingestion.

Point mutation in the band 4.2 gene associated with autosomal recessively inherited erythrocyte band 4.2 deficiency

A patient who represented acute hemolytic crisis was studied. Analysis of the erythrocyte membrane proteins by SDS-PAGE revealed a deficiency of band 4.2. In the family, the sister of the patient who had been clinically normal was also shown to be deficient in band 4.2. Binding studies showed that the propositus' membranes were able to bind normal band 4.2 protein as much as control. It was suggested that the binding sites for the protein were prepared on the membrane. We analyzed the band 4.2 cDNA of the propositus and detected a mutation that changes a codon for alanine to one for threonine at residue 142. Band 4.2 exon III of genomic DNA which included the mutation site was amplified and sequenced directly in the family members, and it was revealed that only the homozygotes of the mutation allele manifested band 4.2 deficiency and the parents, who were heterozygotes, showed normal amounts of band 4.2. Recently, the same mutation was reported as Protein 4.2NIPPON in another 4 cases (Bouhassira et al. Blood 1992: 79: 1846-1854). This study supports the hypothesis that this mutation is the pathogenetic cause of band 4.2 deficiency and not a polymorphism.

Mechanisms of perturbation of erythrocyte calcium homeostasis in favism

Favism is an acute hemolytic anemia triggered by ingestion of fave beans in genetically susceptible subjects with severe deficiency of glucose-6-phosphate dehydrogenase (G6PD) activity. Erythrocytes from 10 favic patients had constantly and markedly increased calcium levels, as compared with values detected in 4 asymptomatic G6PD-deficient controls. Correspondingly, the calcium permeability of erythrocytes, estimated as the fraction of intracellular calcium exchangeable with externally added 45Ca 2+, was invariably enhanced in favism and returned to normal patterns after several months from the acute hemolytic crisis. In favic patients, the levels of erythrocyte calcium ATPase activities showed wide variability, ranging from 2.0–12.9 μmol P i/ml RBC/h, while control values in asymptomatic G6PD-deficient subjects were 10.62 ± 2.03 μmol P i/ml RBC/h. Analysis of the calcium ATPase in situ in erythrocyte membranes from favic patients showed the same molecular mass of 134 kD as observed in the control subjects. Exposure of G6PD-deficient erythrocytes in vitro to autoxidizing divicine, a pyrimidine aglycone strongly implicated in the pathogenesis of favism which leads to late accumulation of intracellular calcium, caused: (i) a marked inactivation of calcium ATPase, without changes in the molecular mass of 134 kD; and (ii) the concomitant loss of spectrin, band 3 and band 4.1, all known substrates of the calcium activated procalpain-calpain proteolytic system. Thus, the increased intraerythrocytic calcium apparently results in the degradation of calcium ATPase observed in some favic patients. It is proposed that both enhanced calcium permeability and a calcium-stimulated degradation of the calcium pump are the mechanisms responsible for the perturbation of erythrocyte calcium homeostasis in favism.

Evaluation of pulse oximetry in anemia from hemoglobin-H disease

A patient with hemoglobin-H (Hb-H) disease developed an acute hemolytic crisis after treatment with trimethoprim and sulfamethoxazole. Despite her poor clinical condition and profound anemia (Hb, 2.7 g/dL), pulse oximetry continued to demonstrate a high O2 saturation percentage. Manipulation of Beer's law shows that anemia theoretically should not affect pulse oximetry values. The literature describes the effects of dyshemoglobinopathies such as carboxyhemoglobinemia and methemoglobinemia on O2 saturation percentage measured by pulse oximetry, but the effect of genetic hemoglobinopathies on pulse oximetry values is largely unreported. Because most hemoglobinopathies do not significantly change the protein-heme electronic interaction, the values of O2 saturation percentage determined through pulse oximetry should remain clinically valid. Hb-H is an exception to this generalization; as in patients with carboxyhemoglobinemia, pulse oximetry measurements showing high O2 saturation percentage do not correspond to high levels of oxygen available for delivery to tissues.