Blood Bilirubin Concentrations Research Articles

Spectral and temporal detection of blood bilirubin level using a point-of-care device.

Bilirubin is a biomarker for liver inflammation used to assess liver functions. Its concentration in the blood has been measured using a range of techniques both in clinical and point-of-care settings. Existing point-of-care devices utilize a spectral approach, namely dual-wavelength absorption measurement, to assess the blood bilirubin concentration. This work examines a novel temporal approach based on the photodegradation of bilirubin in the blood sample. It demonstrates that combining photodegradation characteristics with dual-wavelength measurement produces a more accurate technique for measuring blood bilirubin concentration. Tracking the evolution of absorbed light as a function of time represents a low-cost and simple way of improving the accuracy of point-of-care devices for bilirubin measurements.Clinical Relevance - This work demonstrates a facile and cheap bilirubin monitoring approach that may allow bilirubin monitoring applications in homes after a patient is discharged from a hospital, which may decrease the burden on patients, families, and clinicians.

A Novel Optical Assay System for Bilirubin Concentration Measurement in Whole Blood.

As a biomarker for liver disease, bilirubin has been utilized in prognostic scoring systems for cirrhosis. While laboratory-based methods are used to determine bilirubin levels in clinical settings, they do not readily lend themselves to applications outside of hospitals. Consequently, bilirubin monitoring for cirrhotic patients is often performed only intermittently; thus, episodes requiring clinical interventions could be missed. This work investigates the feasibility of measuring bilirubin concentration in whole porcine blood samples using dual-wavelength transmission measurement. A compact and low-cost dual-wavelength transmission measurement setup is developed and optimized to measure whole blood bilirubin concentrations. Using small volumes of whole porcine blood (72 µL), we measured the bilirubin concentration within a range corresponding to healthy individuals and cirrhotic patients (1.2-30 mg/dL). We demonstrate that bilirubin levels can be estimated with a positive correlation (R-square > 0.95) and an accuracy of ±1.7 mg/dL, with higher reliability in cirrhotic bilirubin concentrations (> 4 mg/dL) - critical for high-risk patients. The optical and electronic components utilized are economical and can be readily integrated into a miniature, low-cost, and user-friendly system. This could provide a pathway for point-of-care monitoring of blood bilirubin outside of medical facilities (e.g., patient's home).

HEPATOPROTECTIVE EFFECT OF CRYOPRESERVED PLACENTA EXTRACT ON THE TETRACHLOROMETHANE LIVER INJURY

Introduction. Toxic lesions of the hepatobiliary system are an important medical and social problem due to the steady increase in the frequency of chemical hepatosis, which develops as a result of accumulation of various xenobiotics in the body. Tetrachloromethane (CCl4) is one of the most studied hepatotoxins. Biochemical and pathomorphological changes in the liver lesions modeled by the administration of CCl4 are analogous to acute hepatitis of various etiologies in humans. As a potential hepatoprotective agent, cryopreserved placenta extract (CPE) attracted our attention. The objective is to characterize the effect of cryopreserved placenta extract on the functional state of the liver of rats with tetrachloromethane-induced damage. Materials and Methods. In vivo study was conducted on 28 male rats weighing 200–220 g. Acute CCl4-induced hepatitis was reproduced by injecting a 50.0% oil solution of CCl4 at a dose of 10 ml/kg body weight of the animal once, which caused acute fatty liver dystrophy. Animals were sacrificed 24 hours after the administration of CCl4. CPE was administered once per day for five days before CCl4 administration. The research material was blood and liver homogenates. The concentration of bilirubin in blood was determined by the spectrophotometrical method. The content of adenosine monophosphoric, adenosine diphosphoric, and adenosine triphosphoric acids was studied in the deproteinized homogenate by chromatographic method. Results and discussion. It was established that the development of CCl4-induced hepatitis is accompanied by the formation of a cholestatic syndrome and a disorder of energy metabolism in liver tissues. This was indicated by an increase (p < 0.001) in the level of total bilirubin by 4.7 times and a decrease (p < 0.001) in the energy charge by 42.6% compared to the indicators of intact rats. Prophylactic five-day administration of CPE led to a decrease (p < 0.001) in the level of total bilirubin by 32.1% and a decrease (p < 0.001) in the levels of direct and indirect bilirubin by 10.6% and 65.1%, respectively, compared to the indicators of animals with experimental toxic hepatitis. This indicated the weakening of the cholestatic syndrome and, indirectly, the weakening of inflammatory infiltration against the background of cytolytic processes in the liver. CPE had an energy-stabilizing effect on hepatocytes of rats with simulated tetrachloromethane liver injury. This was indicated by an increase (p = 0.02) of the energy charge by 18.2% compared to the indicators in the control group. Conclusions. The study showed anticholestatic and energy-stabilizing activity of the cryoextract of placenta used as a prophylactic measure in the model of tetrachloromethane-induced hepatitis.

70 years of bilirubin sensing: towards the point-of-care bilirubin monitoring in cirrhosis and hyperbilirubinemia

We provide a perspective on monitoring the blood bilirubin concentration using simple methods, which are economical and can be adopted in point of care settings. These are a homecare test system, a miniature implant, and a neonatal wearable patch.

Glucose-6-Phosphate Dehydrogenase Status in the Term Newborns and Their Clinical and Other Laboratory Correlates

Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzyme defect in man. Though G6PD deficiency affects every cell in the body, its primary effects are hematological.
 Objectives: The objectives of the study were to determine the G6PD enzyme concentration and deficiency states among the term newborns, to see the impact of the enzyme status with development of neonatal jaundice and to delineate any correlation of the G6PD with other hematological values.
 Materials and Method: Total 100 term newborns were enrolled in the study. Umbilical cord blood sample from the placental end were collected for G6PD enzyme assay, blood counts including reticulocyte count, blood indices and bilirubin estimation. Clinical and other relevant data were collected. Statistical analysis was done by using SPSS 19.0 version.
 Results: Overall G6PD activity was detected 9.86 ± 1.68 U/g Hb and no G6PD enzyme deficiency state was identified. There were no statistically significant differences in the hematological parameters and cord blood bilirubin concentration between male and females. But females have significantly higher G6PD enzyme concentration than males (p=0.002). There were no significant differences in the enzyme concentration in different gestational age groups. There was significant negative correlation between G6PD enzyme and hemoglobin levels, G6PD enzyme concentration with HCT and MCV values.
 Conclusion: This study could not identify any G6PD deficiency state. So further large scale community-based study is needed to validate this finding and also establish the normal G6PD enzyme concentration in the population of Bangladesh.
 Bangladesh J Child Health 2020; VOL 44 (1) :18-23

Incidence and risk factors for severe hyperbilirubinemia in term neonates

Newborn jaundice is caused by increased levels of bilirubin in the blood of the newborn during the first days after birth. Generally, neonatal jaundice does not need to be treated, however, if the blood bilirubin concentration becomes too high, it can cause neurological damage. Due to the prevalence of neonatal jaundice, it is important to assess its risk factors and their importance. This study at the National University Hospital of Iceland from 1997-2018, determines the risk factors for severe neonatal jaundice and their significance. This was a retrospective case control study conducted at the National University Hospital of Iceland. It included all newborns diagnosed with severe jaundice (≥350 micromol/L) following a pregnancy of at least 37 weeks that were treated at the National University Hospital of Iceland from 1997 until 2018. General information on the pregnancy, health of the child at birth, as well as the diagnosis and treatment of jaundice was collected. 339 children met the inclusion criteria for this study. For each child diagnosed with severe jaundice one control was found. The incidence of severe jaundice from 1997 to 2018 was 0.52%. Of the 339 children, 16% were found to have a known significant risk factor for severe neonatal jaundice. The most common were ABO incompatibility and cephalohematoma. Only one child had severe neonatal jaundice because of Rhesus incompatibility. Regression analysis revealed the significant risk factors as followins: shorter pregnancy, bruising at birth, male gender, discharge before 36 hours after birth and relative weight loss the first five days of life. 33% were diagnosed during a -routine doctor's examination five days after birth. Early discharge from the hospital and -relative weight loss the first few days after birth are significant independent risk factors for severe neonatal jaundice. Most cases were diagnosed during a routine doctors five-day check- up. This indicates that there is room for improvement in the evaluation of jaundice in post-natal home care. Monitoring of neonates with Rhesus incompatibility in Iceland exemplary. Boys are at an increased risk for severe neonatal jaundice. It is espe-cially noteworthy given that the negative effect of jaundice on learning ability appears to be greater in boys than in girls.

Clinical characteristics and treatment options of hearing impairment caused by hyperbilirubinemia

SummaryNeonatal hyperbilirubinemia is the most common clinical symptom in neonates. When the concentration of free bilirubin in blood is too high, it crosses through the blood-brain barrier and selectively deposits in specific brain nuclei to cause neurotoxicity and bilirubin neurological dysfunction. The auditory nervous system is highly sensitive to bilirubin. Therefore, auditory neuropathy is the most important or even the only clinical symptom of bilirubin neurological dysfunction. Chronic bilirubin encephalopathy can be classified to three types as mild, moderate and severe，according to the audiological manifestations and other neurological sequelae. Early recognition and intervention of bilirubin-induced hearing impairment is of great significance to improve the speech recognition rate of the referred children. This article reviews the most important studies about the clinical characteristics, pathogenesis and treatment of bilirubin-induced hearing impairment.

Treatment of horses with asthma syndrome

Treatment of horses with asthma syndrome

Determination of Structural and Morphological Parameters of Human Bulbar Conjunctiva from Optical Diffuse Reflectance Spectra

We have developed a method for on-the-fl y retrieval of the volume concentration of blood vessels, the average diameter of the blood vessels, the blood oxygenation level, and the molar concentrations of chromophores in the bulbar conjunctiva from its diffuse reflectance spectra, measured when the radiation delivery and detection channels are spatially separated. The relationship between the diffuse reflectance spectrum of the conjunctiva and its unknown parameters is described in terms of an analytical model, constructed on the basis of a highly accurate approximation analog of the Monte Carlo method. We have studied the effect of localization of hemoglobin in erythrocytes and localization of erythrocytes in the blood vessels on the power of the retrieval of structural and morphological parameters for the conjunctiva. We developed a device for obtaining video images of the conjunctiva and contactless measurements of its diffuse reflectance spectrum. By comparing simulated diffuse reflectance spectra of the conjunctiva with the experimental measurements, we established a set of chromophores which must be taken into account in the model for reproducing the experimental data within the measurement error. We observed absorption bands for neuroglobin in the experimental spectra, and provided a theoretical basis for the possibility of determining its absolute concentrations in the conjunctiva. We have shown that our method can detect low bilirubin concentrations in blood.

Atomic force microscopy of the erythrocyte membrane in obstructive jaundice

The erythrocyte intracellular pressure was calculated using a biomechanical model of the erythrocyte and atomic-force-microscopy (AFM) data. The intracellular pressure was characterized as a function of the model erythrocyte morphology. Based on numerical modeling and data of erythrocyte imaging by AFM, a method was developed to estimate the erythrocyte intracellular pressure by comparing experimental data and the results of numerical calculations. Calculations were performed for erythrocytes of dwarf domestic pigs with and without obstructive jaundice that varied in severity. The erythrocyte membrane was affected with increasing disease severity and blood bilirubin concentration, i.e., the erythrocyte volume increased on average, and substantial changes were observed for erythrocyte intracellular pressure relative to its normal value. As an example, an increase in bilirubin concentration from 5 to 96 μmol/L was associated with an increase in intracellular pressure from 0 to 2.2 kPa. An examination of the erythrocyte membrane surface by high-resolution AMF showed that the membrane is disrupted with an increase in bilirubin concentration and displays lesions and an increasing rupture length.

Albumin dialysis in artificial liver support systems: open-loop or closed-loop dialysis mode?

In artificial liver support systems, the open-loop albumin dialysis mode (OLM) is usually used to remove protein-bound toxins from the blood of patients with liver failure. However, there is still interest in the closed-loop albumin dialysis mode (CLM) because this mode may enable not only the regeneration and reuse of albumin but also the miniaturization of artificial liver systems. In this article, we compared the two modes under a fixed amount of albumin in dialysate experimentally and theoretically. The results show that according to the detoxification efficiency in the 3 hour dialysis for removing albumin-bound bilirubin, CLM is better than OLM. The usage efficiency of albumin in CLM is also higher. Moreover, the advantage of CLM is more significant when the concentration of bilirubin in blood is lower. Under a given amount of albumin in dialysate, if the concentration of bilirubin in blood is high, one may further increase the performance of CLM by means of increasing the flow rate of the albumin dialysate or using the highly concentrated albumin dialysate.

Predictive value of cord blood bilirubin level for subsequent neonatal hyperbilirubinemia in ABO hemolytic term infants

Objective To evaluate the predictive value of cord blood bilirubin levels for subsequent neonatal hyperbilirubinemia in term infants with ABO hemolytic disease. Methods A total of 292 term newborns with ABO hemolytic disease admitted from August 1, 2011 to July 31, 2012 were enrolled. Cord blood bilirubin levels were analyzed and the clinical characteristics of the neonatal hyperbilirubinemia group (n=34) and non-hyperbilirubinemia group (n=258) were compared. A receiver operating characteristic (ROC) curve analysis was performed to identify the predictive value of the occurrence and cut-off point of hyperbilirubinemia in term infants with ABO hemolytic disease. Paired-t-test, Chi-square test and Spearman correlation were used for statistical analysis. Results Of the 292 term infants with ABO hemolytic disease, 34 cases had hyperbilirubinemia, with an incidence of 11.6%. Cord blood bilirubin levels were significantly associated with the presence of hyperbilirubinemia. The mean cord blood bilirubin level in infants who developed hyperbilirubinemia was (52.4±13.2) μmol/L, and was (35.0±8.0) μmol/L for those who did not develop hyperbilirubinemia (t=7.540, P=0.001). When cord blood bilirubin concentration increased, the incidence of hyperbilirubinemia gradually increased (χ2=113.715, P<0.001; rs=7.19, P<0.001). The ROC area under the curve of 0.882 (standard error 0.005, 95%CI: 0.873-0.891, P<0.001) was significant in predicting neonatal hyperbilirubinemia by cord blood bilirubin, and the occurrence of hyperbilirubinemia increased with increasing cord blood bilirubin level. Neonatal cord blood total bilirubin ≥50 μmol/L predicted hyperbilirubinemia, and the positive predictive value was 0.683, negative predictive value was 0.959, sensitivity was 0.690 and specificity was 0.958. Conclusions Cord blood bilirubin level is useful in predicting subsequent neonatal hyperbilirubinemia in term infants with ABO hemolytic disease. Key words: ABO blood-group system; Blood group incompatibility; Hyperbilirubinemia, neonatal; Bilirubin; Fetal blood

The value of serum umbilical cord blood bilirubin and hemolysis three test in the prediction of neonatal hyperbilirubinemia

Objective To study the application value of serum umbilical cord blood bilirubin and hemolysis three test in the prediction of neonatal hyperbilirubinemia. Methods 1 200 cases of healthy newborn were selected, whose mothers were type O blood and fathers were not type O blood. According to the situation of maternal and infant blood type, they were divided into the same maternal and child blood type group with 539 cases and different blood type group with 661 cases; According to the umbilical cord blood bilirubin concentration range was divided into five groups, and analyzed umbilical cord blood bilirubin and hemolysis three test in the prediction of neonatal hyperbilirubinemia. Results (1)The concentrations of umbilical cord blood bilirubin, the incidence of ABO- HDN, the incidence of hyperbilirubinemia in the maternal- fetal blood(O-A/B)group were(38.1±10.3)μmol/L,47.35%,26.02%,respectively, which were all significantly higher than(33.4±7.9) μmol/L,15.21%,14.66% in the maternal blood type(O- O) group(t= 5.8,χ2= 120.7,χ2= 20.1,all P= 0.000);(2)When the concentrations of umbilical cord blood bilirubin was higher, the incidence of hyperbilirubinemia was higher,but the sensitivity and the specificity both were bad;(3)According to the result of hemolysis three to predict the neonatal hyperbilirubinemia, when the concentrations of umbilical cord blood bilirubin was less than 21μmol/L or more than 55μmol/L, the positive predictive value and the specificity both were 100.00%,and the sensitivity was not low(75.00% and 86.96%). Conclusion Detection of umbilical cord blood bilirubin and hemolysis three test in the maternal- fetal blood group incompatibility could predict early hyperbilirubinemia of newborn, which had certain clinically practical value. Key words: Hyperbilirubinemia; Hemolysis; Fetal Blood

Metabolic profile of sows at different parities and with different litter size

The aim of this work was to investigate the change of metabolic profile of sows during the lactation period, taking into consideration both parity and number of piglets in a litter (litter size). In order to do this, 30 sows immediately after farrowing were taken and divided into three groups: sows with two farrowing (first group; n=10), ones with four farrowing (second group; n=10), and ones with five and more farrowing (third group; n=10). In regard to a litter size, 20 sows were divided into two groups: sows with eight piglets (first group; n=10), and sows with 10 and more piglets (second group; n=10). All the sows included in the experiment were mestizos of large Yorkshire and Swedish Landrace. Blood samples were taken on the 2nd and 28th day of lactation. In the blood serum samples there were determined the concentration of total proteins, albumins, Total bilirubin, calcium and inorganic phosphorus. The results have shown that there was not a significant difference in proteinemia between the groups on the 2nd day after farrowing, while on the 28th day of lactation, proteinemia was significantly lower only in the group with ten or more piglets in a litter. In all the groups, except for the group with ten or more piglets in the litter, proteinemia was significantly higher on the 28th compared to the 2nd day of lactation. Albumin concentration in blood serum of different groups of sows followed the same trend as protein concentration, with the only difference that albuminemia in sows with ten or more piglets in a litter was approximately the same on the 2nd and 28th day of lactation. Total bilirubin concentration in blood serum on the 2nd day after farrowing was equal in different groups of sows, provided that in sows with five or more farrowings it was significantly higher in regard to other groups. Similar divergence was also determined on the 28th day after farrowing. The sows of 4th parity had significantly lower and the ones with 10 or more farrowings higher bilirubinemia on the 28th compared to the 2nd day of lactation. Glycaemia was significantly lower in the sows with ten or more piglets in a litter in regard to other groups both on the 2nd and 28th day of lactation. Calcaemia was significantly lower on the 2nd in regard to the 28th day of lactation in all the groups, except for the group of sows with ten or more piglets in a litter. In the group with 10 or more piglets in a litter, calcaemia was significantly lower compared to other groups both on the 2nd and 28th day. The sows of 4. Parity had significantly lower phosphataemia in regard to other groups both on the 2nd and 28th day of lactation. Moreover, on the 28th day of lactation, the sows with 10 or more piglets in a litter had significantly lower phosphataemia in regard to all the other groups, except for the group of sows of 4th parity. Phosphataemia varied between the 2nd and 28th day of lactation in neither group except for the group of sows with 10 or more piglets in a litter. On the basis of the obtained results it can be concluded that between the 2nd and 28th day of lactation significant changes in concentrations of some parameters of metabolic profile in sows in lactation occur. The determined changes are most pronounced in elderly sows as well as in the ones with ten or more piglets in a litter, being a result of impeded bile flow or metabolic load due to the increased activity of mammary glands.

Protection from age-related increase in lipid biomarkers and inflammation contributes to cardiovascular protection in Gilbert's syndrome

Recent epidemiological and clinical data show protection from CVD (cardiovascular disease), all-cause mortality and cancer in subjects with GS (Gilbert's syndrome), which is characterized by a mildly elevated blood bilirubin concentration. The established antioxidant effect of bilirubin, however, contributes only in part to this protection. Therefore we investigated whether mildly elevated circulating UCB (unconjugated bilirubin) is associated with altered lipid metabolism. The study was performed on GS and age- and gender-matched healthy subjects (n=59 per group). Full lipoprotein profile, TAG (triacylglycerols), Apo (apolipoprotein)-A1, Apo-B, lipoprotein(a), the subfractions of LDL (low-density lipoprotein) and selected pro-inflammatory mediators were analysed. A hyperbilirubinaemic rodent model (Gunn rats, n=40) was investigated to further support the presented human data. GS subjects had significantly (P<0.05) improved lipid profile with reduced total cholesterol, LDL-C (LDL-cholesterol), TAG, low- and pro-atherogenic LDL subfractions (LDL-1+LDL-2), Apo-B, Apo-B/Apo-A1 ratio and lower IL-6 (interleukin 6) and SAA (serum amyloid A) concentrations (P=0.094). When the control and GS groups were subdivided into younger and older cohorts, older GS subjects demonstrated reduced lipid variables (total cholesterol and LDL-C, TAG and LDL-C subfractions, Apo-B/Apo-A1 ratio; P<0.05; Apo-B: P<0.1) compared with controls. These data were supported by lipid analyses in the rodent model showing that Gunn rat serum had lower total cholesterol (2.29±0.38 compared with 1.27±0.72 mM; P<0.001) and TAG (1.66±0.67 compared with 0.99±0.52 mM; P<0.001) concentrations compared with controls. These findings indicate that the altered lipid profile and the reduced pro-inflammatory status in hyperbilirubinaemic subjects, particularly in the older individuals, probably contribute additionally to the commonly accepted beneficial antioxidant effects of bilirubin in humans.

The effects of marathon running on expression of the complement regulatory proteins CD55 (DAF) and CD59 (MACIF) on red blood cells

Exercise is known to result in the haemolysis of red blood cells (RBCs). Although mechanical stressors such as footstrike and an increased velocity of blood flow may be involved, the biological mechanisms that underpin RBC haemolysis remain elusive. RBCs are potentially susceptible to lysis by autologous complement activation. RBCs are protected from the lytic effects of complement by regulatory proteins (CRPs) bound to the cell membrane via glycosylphosphatidylinositol (GPI) anchors. This study aimed to determine if marathon running would result in RBC haemolysis through a loss of membrane expression of the CRPs CD55 (decay accelerating factor) and CD59 (membrane attack complex inhibitory factor). Blood samples were obtained from 14 male runners before, within 30 min after, and 24 h after completion of the 2004 London Marathon. RBCs were assessed for cell surface CD55 and CD59 expression using indirect immunofluorescence assays and flow cytometry. No significant changes in the total RBC count, haematocrit or haemoglobin concentrations were found in response to running the marathon (P > 0.05). Blood bilirubin concentrations after the marathon were significantly greater than the pre-race values (P < 0.01). The relative fluorescent intensity (arbitrary units) of CD55 and CD59 expression on RBC membranes did not change in response to the marathon race (P > 0.05). In conclusion, marathon running did not alter the expression of CD55 or CD59 on RBCs, despite concomitant elevations in blood bilirubin concentrations. Consequently, any haemolysis of RBCs that occurred in response to the marathon was not likely due to a loss of membrane bound CRPs and subsequent cell lysis by autologous complement.

Ex Uno Plures: The Concealed Complexity of Bilirubin Species in Neonatal Blood Samples

Blood from jaundiced neonates often contains several isomers of bilirubin in addition to the biosynthetic isomer that causes kernicterus. These isomers are generated during phototherapy or during normal exposure of infants to ambient light. Their presence is generally overlooked or ignored in clinical measurements of circulating bilirubin concentrations and the interpretation of these values. Whether this is justified or clinically important is presently uncertain. However, the presence of isomers may complicate the accurate measurement of free bilirubin concentrations in blood and the use of such values for identifying jaundiced infants at most risk of kernicterus.

Effect of poly(2-methoxyethyl acrylate)-coated oxygenators on haemolysis

Blood contact with artificial device surfaces and mechanical trauma are two major factors for haemolysis. Poly(2-methoxyethyl acrylate) (PMEA) is an amphiphilic polymer with a polyethylene chain that is hydrophobic and a mildly hydrophilic tail. PMEA coating has showed positive effects on protein adsorption, platelet loss, platelet aggregation and post-operative bleeding in previous studies. In this study, effects of poly(2-metoxyethyl acrylate) (PMEA)-coated oxygenators on haemolysis was investigated. PMEA-coated (SX18-Capiox) oxygenators were used. Desorbed erythrocyte, free haemoglobin indirect bilirubin and total bilirubin quantities from fibre samples of oxygenators were studied. Erythrocyte, total bilirubin and direct bilirubin values were measured from blood aliquots taken in five different times during cardiopulmonary by-pass (CPB); baseline (T1), during CPB (T2), at the end of CPB (T3), after protamine injection (T4) and in intensive care (T5). In both coated and non-coated oxygenators haemolysis rate was in clinically acceptable safety range. Average desorbed free haemoglobin was 6663 mg/dl from coated and 29.405 mg/dl from non-coated fibres. Average desorbed total bilirubin was 0.0068 mg/dl from coated and 0.023 mg/dl from non-coated fibres. We observed less haemolysis, as reflected by lower desorbed free haemoglobin and indirect bilirubin from coated oxygenators and less decrease in blood erythrocyte number. Blood bilirubin concentration was low in the coated group when compared to the control group. This study describes the relationship between PMEA coating and haemolysis at the blood contacting surface. PMEA coating reduces red blood cell damage during extracorporeal circulation.

On the Origin of Amniotic Fluid Bilirubin

We studied the relationship between bilirubin concentrations in amniotic fluid and fetal blood in 68 non-hydropic rhesus d-alloimmunized anemic fetuses at first blood sampling. In these alloimmunized fetuses, the amniotic fluid/fetal blood ratio for bilirubin decreased from 0.09 at 28 weeks to 0.05 at 33 weeks. In normal fetuses, amniotic fluid/fetal blood ratios for bilirubin, and for albumin, are in the same range and show a similar decrease during gestation. We conclude that amniotic fluid bilirubin concentration is determined, firstly, by fetal blood bilirubin concentration and, secondly, by the amniotic fluid/fetal blood ratio of albumin. Among five possible pathways bilirubin could take to build up a concentration in amniotic fluid (fetal kidneys, lungs, skin, bowel, membranes), the intramembranous pathway is the only one that is compatible with the amniotic fluid/fetal blood ratios for bilirubin that we found and must therefore be the most important.

Rapid spectrophotometric measurements of total bilirubin in intact and hemolyzed neonatal blood: a feasibility study.

Conventional methods for measuring the total bilirubin concentration in blood require the use of serum or plasma, but physically separating red blood cells from plasma by centrifugation is a time-consuming and potentially dangerous process that does not lend itself to rapid, near-patient testing. Therefore, we have sought to determine whether spectrophotometric measurements of total bilirubin concentration are feasible in unaltered whole blood. We modified an Hb-Quick hemoglobinometer (Avox Systems, Inc., San Antonio, TX), a relatively new, portable, battery-powered instrument that uses disposable cuvettes and a reagentless system to measure total hemoglobin in nonhemolyzed, whole blood. The prototype consisted of an Hb-Quick equipped with light-emitting diodes with emissions at five different wavelengths to measure total bilirubin and total hemoglobin. Using blood samples from neonates with suspected hyperbilirubinemia, we made measurements on plasma from centrifuged samples and on hemolyzed and nonhemolyzed aliquots of the same blood samples. In the first series of experiments, we compared the Unistat bilirubinometer's readings with the prototype's measurements of bilirubin in plasma. There was a close linear correlation between the prototype's measurements and those of the reference instrument (slope=1.01, r(2)=0.991). Subsequently, we used the prototype's measurements on plasma as the reference method and compared them with readings on hemolyzed and nonhemolyzed aliquots of each sample. Readings on hemolyzed and nonhemolyzed aliquots were significantly correlated with the measurements in plasma, but the regression lines did not have a slope of 1. However, when the measurements on hemolyzed and nonhemolyzed blood were scaled appropriately to compensate for the fact that red cells "dilute" the bilirubin in plasma, the correlation coefficients improved, and there was then a 1:1 relationship between the measurements in whole blood and plasma. These preliminary findings demonstrate the feasibility of developing a portable instrument to measure total bilirubin in unaltered whole blood. The advantages of this method are speed, elimination of centrifugation or other sample preparation, and instrument portability. The disadvantage is that the concentration units are unconventional, i.e., milligrams of bilirubin per volume of whole blood. However, the instrument can be programmed to display the total bilirubin concentration in traditional units, e.g., milligrams of bilirubin per volume of plasma.