Regional cerebral tissue oxygen saturation changes following blood transfusion in neuro-intensive care unit patients - a pilot observational study.

BACKGROUND: Although central venous oxygen saturation (ScvO2 ) is used to decide on red blood cell (RBC) transfusion, whether its improvement is associated with parallel improvement in cerebral oxygenation is not adequately studied. This study looked at changes in regional cerebral tissue oxygen saturation (rSO2 ) following RBC transfusion in neuro-intensive care unit (ICU) patients. METHODS: In this prospective observational pilot study, rSO2 was measured in adult neuro-ICU patients before RBC transfusion, at the end and at 6, 12, 18 and 24 h after RBC transfusion. rSO2 measurements were taken using cerebral oximetry on both sides of the hemicraniums. Haemoglobin, central venous pressure, ScvO2 and temperature were recorded during the study period. Arterial oxygen content, central venous oxygen content and cerebral fractional oxygen extraction were calculated. Mann Whitney U test was used to study the changes in variables at baseline and at 24 h following RBC transfusion. Friedman's test was used to study changes in parameters from baseline to 24 h post-transfusion. A P value of <0·05 was considered to be significant. RESULTS: The data from 13 subjects were analysed. rSO2 increased significantly following RBC transfusion on both sides of the brain (P = 0·002, P = 0·007), with a corresponding decrease in cerebral fractional oxygen extraction (P = 0·001, P = 0·007). CONCLUSIONS: RBC transfusion increased rSO2 significantly on both sides of the brain. As patients' outcomes were not studied, whether this increase in regional cerebral oxygen saturation is beneficial or if it is because of excess DO2 is still unclear. Further studies are required to clarify this issue.

The effect of blood transfusion on central venous oxygen saturation in critically ill patients admitted to a neurointensive care unit.

BACKGROUND: Literature suggests poorer outcomes during anaemia as well as following red blood cell transfusion (BT) in brain injured patients. Recently, central venous oxygen saturation (ScvO2 ) has been proposed as a physiological trigger to guide red BT. In this study, we looked at ScvO2 changes following BT in patients admitted to a neurointensive care unit (NICU). STUDY DESIGN: In this prospective, observational study, adult, acutely ill neurological patients of >18 years were recruited. The following parameters were measured before and immediately after transfusion and then at 6, 12, 18 and 24 h after transfusion: haemoglobin (Hb), ScvO2 and central venous oxygen partial pressure (PcvO2 ) (blood sampled from central venous catheter). Simultaneously, hemodynamic parameters [central venous pressure (CVP), heart rate (HR), mean arterial pressure (MAP) and systolic blood pressure (SBP)] were also noted. RESULTS: Data from 70 adult patients were analysed. Following BT, significant improvement was noted in Hb, ScvO2 and all hemodynamic parameters. The ScvO2 changes correlated significantly with the number of units of BT (P = 0·039), pre-transfusion Hb (P = 0·010), ScvO2 (P = 0·001) and PcvO2 (P = 0·001). When receiver operating characteristic (ROC) curves were drawn, optimum cut-off values of baseline ScvO2 and Hb to predict the need for transfusion in terms of oxygen delivery were 70% and 8·6 gm dL-1 respectively. DISCUSSION: Baseline ScvO2 <70% appears to be a useful physiological trigger for deciding the need for BT in brain injured patients. Whether improvement in ScvO2 leads to improvement in regional brain oxygenation needs to be studied.

HPLC studies in hemoglobinopathies.

An accurate diagnosis of beta -thalassemia carriers, homozygous patients and identification of different structural hemoglobin variants is important for epidemiological studies as well as for management and prevention of the major hemoglobin disorders. There are many electrophoretic and chromatographic approaches for estimation of HbA2 and Hb F but cation exchange HPLC (CE-HPLC)using automated dedicated machines like the Variant Hb testing system have become the method of choice for these investigations. CE-HPLC also helps in the presumptive identification of many abnormal hemoglobin variants and has been useful for both neonatal screening of sickle cell disease as well as second trimester prenatal diagnosis of thalassemia by fetal blood analysis. Other applications of HPLC in hemoglobinopathies include separation of globin chains, measuring the ratio of gamma globin chains (Ggamma/Agamma) and the recently described denaturing HPLC for detecting mutations in both alpha and beta globin genes.

Clinical examination and hematological data in asymptomatic & apparently healthy school children in a boarding school in a tribal area.

In a boarding school of Maharashtra State of India 314 students (Bhil & Pawar) were examined clinically and blood was examined. Anemia was present in 16.2% male & 38.3% female. B (Beta). Thalasemia trait was present in 1.6% male & 2.4% female. Sickle cell trait was present in 21.3% male and 14.4% female and sickle cell disease in 0.6% student. G6PD deficiency was seen in 5.1% male & 4.8% female students.

Red cell genetic abnormalities, beta-globin gene haplotypes, and APOB polymorphism in the Great Andamanese, a primitive Negrito tribe of Andaman and Nicobar Islands, India.

The Great Andamanese are a primitive Negrito tribe of the Andaman and Nicobar Islands, India, with a total population of 37. We studied 29 individuals from eight families from this population for abnormal hemoglobins, G6PD deficiency, DNA haplotypes, and apolipoprotein B (APOB, gene) polymorphism. Hb E was detected in five individuals, the prevalence of Hb E heterozygotes being 14.3%. One individual had beta-thalassemia trait. One female was G6PD deficient and showed the G6PD Orissa mutation. Haplotype analysis of the beta-globin gene cluster showed that the betaE chromosomes were linked to two haplotypes (- - - - - + + and + + - + + + +) representing the framework 1 gene, whereas the betaA chromosomes showed eight different haplotypic patterns corresponding to framework 1 and 3 genes. APOB polymorphism analysis showed that the 631-base-pair (bp) allele was the predominant one with a high homozygosity rate, which could be due to the higher rate of inbreeding in this isolated group. The presence of Hb E and our findings on haplotype analysis supports the hypothesis that the Great Andamanese are reasonably believed to be the surviving representatives of the Negrito race that once flourished in the entire Southeast Asian region in ancient times.

Some aromatic nitrate esters: synthesis, structural aspects, thermal and explosive properties.

1-(2-Nitroxyethylnitramino)-2,4,6-trinitrobenzene (I-A), 1, 3-bis(2-nitroxyethylnitramino)-2,4,6-trinitrobenzene (II-A) and 1,3, 5-tris(2-nitroxyethylnitramino)-2,4,6-trinitrobenzene (III-A) have been prepared by condensing picryl chloride, styphnyl chloride and 1, 3,5-trichloro-2,4,6-trinitrobenzene with ethanol amine, respectively, followed by nitration. These compounds have been characterized by infrared spectrum (IR), the elemental analysis and 1H NMR. Further, these compounds have been studied for their thermal and explosive properties. The activation energy of thermal decomposition of these compounds has also been determined using the Ozawa and the Kissinger methods. The data on explosive properties indicate that the impact, friction and velocity of detonation (VOD) increase with an increase in the number of nitrate ester groups.

Detection of the beta s gene: an evaluation of the solubility test against automated chromatography and haemoglobin electrophoresis.

The solubility test is evaluated against automated high-performance liquid chromatography (HPLC) and haemoglobin (Hb) electrophoresis for its efficacy in screening for the beta s gene in population groups in remote areas. Blood samples taken from 3246 individuals from the tribal populations of the Dhule and Gadchiroli districts of Maharashtra state were analysed by all three methods. The solubility test detected 871 out of 932 individuals positive for the beta s gene by HPLC and Hb electrophoresis, and showed an overall sensitivity of 93.8% and specificity of 100%, with a positive predictive value of 100% and negative predictive value of 97.4%. Both HPLC and Hb electrophoresis are relatively expensive and not available in most laboratories in remote tribal areas, where the frequency of the beta s gene is very high. We conclude that the solubility test could be used for preliminary screening to determine the prevalence of the beta s gene in different population groups, particularly in remote areas where other facilities are not available. Individuals who test positive for the beta s gene by the solubility test require further investigation by either HPLC or Hb electrophoresis.

Splenomegaly in school children in a remote tribal area of Dhole district, Maharashtra.

Sickle-cell gene is known to protect against P. falciparum infection and provides a selective survival advantage in those areas where P. falciparum infection is endemic. This protection is not absolute and many other factors, inherited and acquired also contribute to the immunity against P. falciparum infection. We investigated incidence of splenomegaly and typical history of malaria in the past two years in apparently healthy school children in a tribal area in Dhole district of Maharashtra to see whether the incidence of malaria (splenomegaly and typical history) was different in children having sickle-cell trait to that of those who did not have this trait. A total of 480 school children were clinically examined for splenomegaly and history of typical malaria fever and/or blood slide positivity for malaria in the past two years. About 9.55 per cent of normal population had either splenomegaly or convincing history of malarial infection in the past two years which is not statistically different from the sickle-cell trait patients having evidence of past malaria (8.79 per cent; p > 0.05).

The influence of alpha-thalassaemia on the haematological & clinical expression of sickle cell disease in western India.

We evaluated the clinical and haematological features of 29 sickle cell anaemia patients with associated alpha-thalassaemia and 22 sickle cell homozygotes with a normal alpha-globin genotype from western India. The presence of alpha-thalassaemia resulted in significantly higher haemoglobin (Hb), haematocrit (HCT), red blood cells counts (RBC) and haemoglobin A2 (HbA2) levels but lower mean cell haemoglobin (MCH) and mean cell volume (MCV). The clinical presentation in these patients was also milder with fewer episodes of painful crisis, chest syndromes, infections, requirement of hospitalization and blood transfusions. However, splenomegaly was more common as compared to the patients with a normal alpha-globin genotype. It is evident from the present study that alpha-thalassaemia could be an important genetic factor modulating the clinical expression and haematological severity of sickle cell anaemia in this region.

Trimodal distribution of HbS levels in sickle heterozygotes--an useful predictor of the alpha-genotype for population screening.

The trimodal distribution of HbS levels in sickle heterozygotes has been used as an indirect approach to determine the prevalence of alpha-thalassaemia in different population groups. We used this approach to predict the alpha-genotypes of 124 sickle cell heterozygotes where the HbS concentration varied from 20 to 46 per cent with antimodes at 28.0 and 33.0. The alpha-genotypes in these individuals were also determined by Southern blot hybridization. We predicted homozygous (-alpha/-alpha) or heterozygous (-alpha/alpha alpha) alpha-thalassaemia-2 in 78 subjects by the trimodal distribution of HbS. However, actual genotyping showed that 75 patients had alpha-thalassaemia. Forty six of the 47 subjects with a normal alpha-globin genotype (alpha alpha/alpha alpha) could be predicted indirectly. The overall sensitivity was 100 per cent and specificity was 94.2 per cent with a positive predictive value of 96.2 per cent and negative predictive value of 100 per cent. As alpha-genotyping is very expensive and not feasible in most laboratories in India, we conclude that the trimodal distribution of HbS levels is a suitable method for screening for alpha-thalassaemia in population studies.