Pulmonary complications

Effect of oral arginine supplementation on exhaled nitric oxide concentration in sickle cell anemia and acute chest syndrome

INTRODUCTION

Decreased exhaled nitric oxide levels (FE(NO)) have been described in patients with sickle cell disease (SCD) and a history of acute chest syndrome (ACS) when compared with non-ACS controls. Oral arginine supplementation has been shown to increase FE(NO) in healthy participants, but its effect in SCD patients is not known.

OBJECTIVE

To determine the effect of oral arginine intake on FENO in sickle cell patients with and without history of ACS, and in healthy controls.

HYPOTHESIS

No differences in the FE(NO) increase were seen in SCD patients with a history of ACS (ACS+) compared with healthy controls (HC) and SCD patients without history of ACS (ACS-).

MATERIALS AND METHODS

ACS+ (n=6), ACS- (n=9), and HC (n=7) patients were studied. At baseline, and after the administration of escalating doses of oral L-arginine (0.1, 0.2, and 0.4 g/kg), serial measurements were made of the following: FE(NO), plasma concentrations of arginine, ornithine, citrulline, aspartate, glutamate, arginine/ornithine ratio, nitrite, nitrate, heart rate (HR), respiratory rate (RR), blood pressure (BP), oxygen saturation (SpO2), forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC).

MAIN RESULTS

At baseline, FE(NO) did not differ among the groups. ACS- and ACS+ groups were deficient in arginine, and had decreased FEV1, FVC, and SaO2 when compared with HC patients. After arginine supplementation, FE(NO), arginine, ornithine, citrulline, nitrite, and the arginine/ornithine ratio increased similarly in all groups. Changes from baseline for HR, BP, SpO2, RR, FEV1, and FVC were minimal and similar in all groups.

CONCLUSIONS

In contrast to our earlier study, ACS+ patients had similar FE(NO) values when compared with ACS- and HC patients. All SCD patients were arginine deficient at baseline and showed impairment in respiratory physiology when compared with HC patients. After arginine supplementation, FE(NO) concentration increased in all groups to a similar degree, and lung function and physiologic parameters were minimally affected. The physiologic significance of alterations in FE(NO) in SCD patients and its relationship to ACS predilection requires further delineation.

Managing acute chest syndrome of sickle cell disease in an African setting

Despite the fact that acute chest syndrome contributes immensely to morbidity and mortality in patients with sickle cell anaemia, its exact aetiopathogenesis is very complex and not yet well understood. Therefore, a high index of suspicion is needed in its diagnosis, and appropriate treatment should be commenced as soon as possible to prevent lethal complications of this condition, especially in Nigeria where appropriate diagnostic and therapeutic facilities may not be readily available. This is very important, as it may even develop on hospital admission. There is a need to further investigate preventive measures such as the use of hydroxyurea and the newly introduced Nicosan, especially in those people with recurrent disease, in order to reduce both short- and long-term complications of this syndrome among sickle cell patients in Nigeria.

Clinical presentation of acute chest syndrome in sickle cell disease

In this study the records of 45 patients with sickle cell disease involved in 63 presentations of acute chest syndrome at the Princess Margaret Hospital in Nassau, the Bahamas, between 1997 and 2001 were examined. Patients were divided into three groups on the basis of age (<13 years, 13-18 years, >/=19 years) with a view to assessing clinical presentation. The incidence of symptoms, physical signs, and laboratory findings were enumerated and significant differences between age groups determined. The data were analysed using analysis of variance, t test, and chi(2) test and compared with existing knowledge on the subject. This study proposed to evaluate the clinical presentation of acute chest syndrome with emphasis on historical and physical findings, and to encourage the physician to maintain a high index of suspicion for the condition in susceptible patients. It was found that presentation varied significantly with age groups, children presenting most classically with fever and cough and adults, with chest pain. The 13-18 age group emerged as the group which presented most frequently with the typical symptoms of chest infection, thus potentially making diagnosis easier. Of note, the most frequent finding was a normal examination, while the second commonest physical finding was crepitations on auscultation of the chest.

Hematopoietic stem cell transplantation in sickle cell disease

Since the first report of a young girl affected by sickle cell anemia, treated successfully by bone marrow transplantation (BMT) for acute myeloid leukemia, more than 200 patients have been transplanted worldwide for sickle cell anemia. The disease-free survival (DFS) is good (80-85% in several series), even though many children who received allografts had already significant sickle-related complications. The best results are obtained in young children who have HLA-identical sibling donors and are transplanted early in the course of the disease (DFS: 93%). Future directions in the field of stem cell transplantation of sickle cell anemia include (1) the establishment of new protocols with less toxicity, but still effective, (2) adapted conditioning regimen for adult patients, and (3) new sources of stem cells for broader application: umbilical cord blood and volunteer unrelated donors.

Pulmonary manifestations of sickle cell disease

Pulmonary complications account for significant morbidity and mortality in patients with sickle cell disease. Clinical lung involvement manifests in two major forms: the acute chest syndrome and sickle cell chronic lung disease. Acute chest syndrome is characterised by fever, chest pain, and appearance of a new infiltrate on chest radiograph. Sickle cell chronic lung disease, on the other hand, manifests as radiographic interstitial abnormalities, impaired pulmonary function, and, in its most severe form, by the evidence of pulmonary hypertension. Progress has been made in understanding the pathophysiology and management of these complications. In this review the current knowledge of the mechanism, diagnosis, and treatment of pulmonary complications of sickle cell disease are discussed.

Cardiopulmonary responses to exercise in women with sickle cell anemia

Multiple factors contribute to exercise intolerance in patients with sickle cell anemia, but little information exists regarding the safety of maximal cardiopulmonary exercise testing (CPET) or the mechanisms of exercise limitation in these patients. The purpose of the present study was to examine these issues. Seventeen adult women with sickle cell anemia underwent symptom-limited maximal CPET using cycle ergometry and ramp protocols; blood gases and lactate concentrations were measured every 2 minutes. All patients completed CPET without complications. No patient demonstrated a mechanical ventilatory limitation to exercise or had evidence of myocardial ischemia. However, we observed three pathophysiologic patterns of response to exercise in these patients. Eleven patients had low peak VO2, low anaerobic threshold (AT), gas exchange abnormalities, and high ventilatory reserve; this pattern is consistent with exercise limitation due to pulmonary vascular disease in this patient subgroup. Three patients had low peak VO2, low AT, no gas exchange abnormalities, and a high heart rate reserve, a pattern consistent with peripheral vascular disease and/or a myopathy. The remaining three patients had low peak VO2, low AT, no gas exchange abnormalities, and a low heart rate reserve; this pattern of exercise limitation is best explained by anemia.

Plastic bronchitis and the role of bronchoscopy in the acute chest syndrome of sickle cell disease

STUDY OBJECTIVES

To review the prevalence, clinical features, and role of bronchoscopy in patients with plastic bronchitis during the acute chest syndrome (ACS) of sickle cell disease (SCD).

DESIGN

Eight-year review of clinical experience.

SETTING

Tertiary referral children's hospital.

PATIENTS

Twenty-six pediatric inpatients with 29 ACS episodes requiring diagnostic bronchoscopy.

RESULTS

Of the pediatric inpatients with ACS who underwent bronchoscopy, plastic bronchitis was diagnosed in 21 of 29 episodes (72%). There was no difference in clinical features between the patients with and without plastic bronchitis. Bronchoscopy was an essential diagnostic tool, but its therapeutic benefits were doubtful.

CONCLUSIONS

This is the first report of the prevalence of plastic bronchitis in patients with ACS of SCD. In our patient population, this condition was found to be common. The role of diagnostic bronchoscopy is essential. A large series, multicenter study is required to determine whether bronchoscopy and BAL are therapeutically beneficial when added to currently practiced supportive care.

Acute chest syndrome in sickle cell disease. Crucial considerations in adolescents and adults

Rapid recognition of acute chest syndrome is essential in patients with sickle cell disease. The condition can be particularly severe in adolescents and adults and often leads to death. In this article, the authors review the challenges of evaluating the syndrome and outline current treatment and supportive care.

The perioperative complication rate of orthopedic surgery in sickle cell disease: report of the National Sickle Cell Surgery Study Group

Orthopedic disease affects the majority of sickle cell anemia patients of which aseptic necrosis of the hip is the most common, occurring in up to 50% of patients. We conducted a multicentered study to determine the perioperative complications among sickle cell patients assigned to different transfusion regimens prior to orthopedic procedures: 118 patients underwent 138 surgeries. The overall serious complication rate was 67%. The most common of these were excessive intraoperative blood loss, defined as in excess of 10% of blood volume. The next most common complication was sickle cell-related events (acute chest syndrome or vaso-occlusive crisis), which occurred in 17% of cases. While preoperative transfusion group assignment did not predict overall complication rates, higher risk procedures were associated with significantly higher rates of overall complications. Transfusion complications were experienced by 12% of the patients. Two patients died following surgery. Both deaths were associated with an acute pulmonary event. The 52 patients undergoing hip replacements experienced the highest rate of complications with excessive intraoperative blood loss occurring in the majority of patients. Sickle cell-related events occurred in 19% of patients, and surgical complications occurred after 15% of hip replacements and included postoperative hemorrhage, dislocated prosthesis, wound abscess, and rupture of the femoral prosthesis. There were twenty-two hip coring procedures. Acute chest syndrome occurred in 14% of the patients. Overall, decompression coring was a safer, shorter operation. A randomized prospective trial to determine the perioperative and long-term efficacy of core decompression for avascular necrosis of the hip in sickle cell disease is needed. In conclusion, this study demonstrates a high rate of perioperative complications despite compliance with sickle cell perioperative care guidelines. Pulmonary complications and transfusion reactions were common. This study supports the results previously published by the National Preoperative Transfusion in Sickle Cell Disease Group. These results stated that a conservative preoperative transfusion regimen to bring hemoglobin concentration to between 9 and 11 g/dl was as effective as an aggressive transfusion regimen in which the hemoglobin S level was lowered to 30%.

Nitric oxide successfully used to treat acute chest syndrome of sickle cell disease in a young adolescent

OBJECTIVES

To report a case of acute chest syndrome (ACS) of sickle cell disease treated successfully with nitric oxide and to review the physiologic effects of nitric oxide and its potential ability to improve outcome in ACS.

DESIGN

Descriptive case report.

SETTING

Eighteen-bed pediatric intensive care unit in a university children's hospital.

PATIENT

A 15-yr-old black male with sickle cell disease, bilateral pulmonary infiltrates, refractory hypoxemia, and unstable hemodynamics.

INTERVENTION

In addition to exchange transfusion, invasive hemodynamic monitoring, and aggressive ventilatory support, inhaled nitric oxide was administered in the gas mixture in a concentration of 20 ppm for 72 hrs.

MEASUREMENTS AND MAIN RESULTS

Cardiac output, pulmonary arterial pressure, pulmonary artery occlusion pressure, systemic vascular resistance, pulmonary vascular resistance, shunt fraction, and alveolar-arterial oxygen gradient were compared with and without inhaled nitric oxide. Marked reductions in pulmonary arterial pressure and pulmonary vascular resistance were noted. Cardiac output improved, and shunt fraction and alveolar-arterial oxygen gradient were markedly reduced. The patient required decreased ventilator and hemodynamic support and rapidly made a complete recovery.

CONCLUSIONS

Nitric oxide may be beneficial for patients with ACS because of its ability to ameliorate pulmonary hypertension and ventilation/perfusion mismatch. Nitric oxide may confer some protection against polymerization of sickle hemoglobin and exert a reversible antiplatelet effect that may be beneficial in ACS. Further study is necessary to determine the safety and efficacy of inhaled nitric oxide as a treatment for ACS.

The lung in sickle cell disease

Sickle cell disease is the most common inherited disorder in African-Americans. Although the primary defect is hematological, the changes in the erythrocytes lead to a vasculopathy with multiorgan injury. The pulmonary complications, i.e., acute chest syndrome and chronic sickle cell lung disease, are significant causes of morbidity and mortality. The pulmonary manifestations result from a unique constellation of factors which come into play in sickle cell disease. Based on the growing understanding of the molecular and cellular biology of sickle cell disease, new therapies are being developed that are likely to ameliorate the natural history of this disease and its complications.

Sickle cell disease: clinical management

Sickle cell syndromes are a group of inherited disorders of haemoglobin structure that have no cure in adults at the present time. Bone marrow transplantation in children has been shown to be curative in selected patients. The phenotypic expression of these disorders and their clinical severity vary greatly among patients and longitudinally in the same patient. They are multisystem disorders and influence all aspects of the life of affected individuals including social interactions, family relations, peer interaction, intimate relationships, education, employment, spiritual attitudes and navigating the complexities of the health care system, providers and their ancillary functions. The clinical manifestations of these syndromes are protean. In this review emphasis is placed on four sets of major complications of these syndromes and their management. The first set pertains to the management of anaemia and its sequelae; the second set addresses painful syndromes both acute and chronic; the third set discusses infections; the fourth section deals with organ failure. New experimental therapies for these disorders are briefly mentioned at the end. Efforts were made to include several tables and figures to clarify the message of this review.

The management of crisis in sickle cell disease

The symptoms and signs of sickle cell disease are exacerbated in times of crisis, characterized by tissue infarction or worsening anaemia. Prompt medical intervention is required in these distressing situations to provide relief and comfort to the patient. Effective analgesia is crucial in treating the painful crisis of sickle cell disease. The haemoglobinopathy may cause hyposthenuria with reduced ability to excrete the sodium load in normal saline. A 5% dextrose solution or 5% dextrose in 25% normal saline is therefore recommended for intravenous hydration. As the leading cause of morbidity and mortality in sickle cell disease, infections call for vigorous antibiotic therapy. Oxygen administration should be reserved for hypoxic patients, and blood transfusion given only when really indicated. Acute chest syndrome and cerebrovascular accidents are life-threatening complications of sickle cell disease whereas priapism can cause important long-term sequelae; all deserve urgent attention. In the long term, comprehensive care is cost-effective in reducing the frequency and adverse effects of sickle cell crisis.