Lung Function Abnormalities in Sickle Cell Anaemia

Background. Abnormalities in lung function tests have been shown to commonly occur in a majority of patients with sickle cell disease (SCD) even at steady state. The prevalence and pattern of these lung function abnormalities have been described in other populations but this is unknown among our sickle cell cohort. There is generally little information available on risk factors associated with the lung function abnormalities and its relevance in patient care. Method. This was an analytical cross-sectional study involving 76 clinically stable, hydroxyurea-naive adult Hb-SS participants and 76 nonsickle cell disease (non-SCD) controls. A structured questionnaire was used to obtain sociodemographic data and clinical history of the participants. Investigations performed included spirometry, pulse oximetry, tricuspid regurgitant jet velocity (TRV) measurements via echocardiogram, complete blood counts, free plasma haemoglobin, serum urea, and creatinine. Results. Weight, BMI, mean FVC, and FEV1% predicted values were comparatively lower among the Hb-SS patients (p < 0.001). Abnormal spirometry outcome occurred in 70.4% of Hb-SS patients, predominantly restrictive defects (p < 0.001), and showed no significant association with steady-state Hb, WBC count, free plasma haemoglobin, frequency of sickling crisis, chronic leg ulcers, and TRV measurements (p > 0.05). The mean oxygen saturation was comparatively lower among Hb-SS patients (p < 0.001). Conclusion. Measured lung volumes were significantly lower in Hb-SS patients when compared to non-SCD controls and this difference was not influenced by anthropometric variance. Lung function abnormalities, particularly restrictive defects, are prevalent in Hb-SS patients but showed no significant association with recognized markers of disease severity.

Extracellular vesicles in the circulation: are erythrocyte microvesicles a confounder in the plasma haemoglobin assay?

Blood contains a mixture of extracellular vesicles from different cell types, primarily platelets, endothelial cells, leucocytes and erythrocytes. Erythrocytes are the most abundant cell type in blood and could, especially in certain pathologies, represent an important source of vesicles. Since erythrocytes contain the haemoglobin components iron and haem, which are potentially toxic, it is important to investigate the contribution of vesicle-associated haemoglobin to total cell-free haemoglobin levels. To our knowledge, this is the first time that cell-free plasma haemoglobin has been differentiated into vesicle-associated and molecular species. We investigated the contribution of vesicle-associated haemoglobin in residual patient material that was routinely analysed for total cell-free plasma haemoglobin. All patient samples included in the study were haemolytic with total cell-free haemoglobin concentration ranging from 80 to 2500 mg/l. In the majority of the samples, total cell-free haemoglobin concentration was between 100 and 200 mg/l. No haemoglobin could be detected in the vesicle fraction, indicating that the contribution of vesicle-associated haemoglobin to total cell free-haemoglobin levels in plasma is negligible. It is important to investigate whether erythrocyte vesicles are not formed in blood or that their production is not increased during pathologies associated with haemolysis or that the clearance rate of the vesicles surpasses the formation rate.

Haemolysis during cardiopulmonary bypass: how to reduce the free haemoglobin by managing the suctioned blood separately

During cardiopulmonary bypass (CPB) the collection of the patient’s blood from the operating area is of fundamental importance. This blood is collected in the cardiotomy reservoir using field suckers and can be managed in different ways. It can be filtered in the cardiotomy reservoir and redirected to the venous reservoir, then oxygenated and returned to the patient, or it can be managed separately: collected in the cardiotomy reservoir, treated at the end of the operation and only after this, returned to the patient. The aim of this study is to determine in vivo the effect of a separate management of the suction blood from the operative field, using the Avant D903 oxygenator (Dideco, Mirandola, Italy). Twenty-one patients undergoing coronary artery bypass graft surgery with CPB were selected and put into two groups at random. In the control group ( n 10) the suction blood in the cardiotomy reservoir was filtered and immediately redirected into the venous reservoir, oxygenated and returned to the patient. In the study group ( n 11) the suctioned blood was collected in the D903 Avant’s (Dideco) cardiotomy reservoir and returned to the patient only after having been washed at the end of the operation, using a Compact Advanced (Dideco), as required. Clinical data demonstrated that while in the study group it was possible to keep the free plasma haemoglobin (FPH) concentrations the same as at the beginning, in the control group there was a significant increase in FPH from 5.0 3.5 mg/dl (baseline) to 37 16.7 mg/dl (120 min after CPB).

Intravenous Chlormethiazole — Haemolysis with Concentrated Solutions

Since the current clinical concentration of chlormethiazole solutions (0.8%) may require the infusion of large volumes of fluid, it was decided to examine the effects on haemolysis of infusing higher concentrations of chlormethiazole into a central vein. Approximately one gram of chlormethiazole was infused into the inferior vena cavae of six anaesthetised greyhounds over each half hour using, successively, 0.8%, 1.2%, 2%, 5%, 10%, and 20% solutions of chlormethiazole. Free plasma haemoglobin levels were measured at five minute intervals, and blood chlormethiazole levels at 15 minute intervals. A rapidly progressive haemolysis occurred when the 5 or 10% solutions were infused. In a further four greyhounds, one gram of chlormethiazole was infused over each half hour using a 0.8% solution, whilst progressively hyperosmolar dextrose solutions were infused at the same rates in succeeding half hours as the concentrated chlormethiazole solutions had been infused in the first six dogs. No haemolysis occurred in these control animals. Chlormethiazole blood levels were similar in each group. Loss of chlormethiazole into the infusion tubing was examined and found to be 20% for the 0.8% solution, and 10% for the 1.2% solution, but was insignificant with the other subsequently infused concentrations of chlormethiazole. It is concluded that rapid progressive haemolysis occurs in association with the infusion of chlormethiazole solutions when concentrations of greater than 5 or 10% are infused into the inferior vena cavae of anaesthetised greyhounds.