Low-concentration morphine infusion does not compromise packed red blood cell transfusion.

Regulations currently prohibit co-administration (through the same line) of red blood cell transfusions with continuous morphine infusions for pain management, resulting in additional intravenous access or interrupted analgesic therapy in seriously ill children. Packed cells that had been in contact with morphine 0.1 or 1.0 mg/mL and infused through a mock central venous catheter system showed no evidence of hemolysis when compared with control samples. There is thus no need to interrupt analgesic therapy or start another venous access line in order to give a coincident blood transfusion.

Does merging operations always increase cost-effectiveness? An analysis of combined adult/pediatric versus stand-alone pediatric laboratory services.

An analysis of acuity adjusted health center data from participating Canadian institutions was performed to evaluate the relative cost-effectiveness of adult, pediatric, and combined adult/pediatric health centers. Acuity adjusted costs were then adjusted for the different rates of pay in each laboratory. A synthesis was performed to model the cost-effectiveness of a theoretical combination of stand-alone adult and pediatric laboratories based on a 12% pediatric caseload. The results arising from the model were then compared with existing combined adult/pediatric health centers. The laboratory costs of the modelled adult/pediatric health centers (mean = 134, SD = 15, n = 11) are significantly (p < 0.05) lower than the existing combined adult/pediatric institutions. The actual costs of existing combined adult/pediatric laboratories average 13.4% more than the modelled combination of existing stand-alone pediatric and adult facilities. The results of this analysis should at least serve as a cautionary note for those who are considering merging pediatric and adult health center laboratory services for the purpose of achieving greater cost-effectiveness.

Determination of the effect of pH and foetal haemoglobin fraction on haemoglobin oxygen saturation readings by the OSM3 hemoximeter.

The visible absorption spectrum of oxyhaemoglobin depends on its content of foetal haemoglobin and on the pH of the blood. These variables are known to affect oxygen saturation readings measured by the OSM3 Hemoximeter. As the hemoximeter estimates foetal haemoglobin content from the absorption spectrum of oxyhaemoglobin, this estimation is affected by pH. We quantified the effect of pH on oxyhaemoglobin reading in order to calculate a correction factor to adjust for pH. We manipulated a pool of fresh heparinized cord blood samples to produce a range of pH values from 6.99-7.53 in fully oxygenated blood with a carbon dioxide tension of 5.3 kPa. We measured oxygen saturation and percent foetal haemoglobin using an OSM3 Hemoximeter and pH with a linked blood gas analyser. The effect of pH on readings of saturation and fractional foetal haemoglobin was confirmed and a correction factor was calculated. The value of KHbF, the coefficient used in the OSM3 Hemoximeter to estimate the amount of fractional foetal haemoglobin present in a sample, was determined to be 18.3, which slightly but significantly differed (p = 0.04) from the 18.6 used by the OSM3 Hemoximeter. An equation was derived to correct the errors made by pH on the saturation measurement of oxygenated blood.

Tilapia--a source of hypoxia-resistant islet cells for encapsulation.

Encapsulation of pancreatic islets prevents graft revascularization after transplantation, resulting in graft hypoxia and attrition. Hypoxia-resistant islets would be ideal for encapsulation. Tilapia, a tropical teleost fish, have large, anatomically discrete islets that can be easily harvested without expensive, fickle islet isolation procedures and that provide mammalian-like glucose tolerance profiles when transplanted into diabetic recipients. Because tilapia can live in stagnant water, we speculated that tilapia islets might tolerate lower oxygen tensions than mammalian islets. Tilapia and rat islets (n = 30) were placed in paired 60-mm Petri dishes containing 10 mL of deoxygenated CMRL-1066 media and cultured together in sealed chambers gassed with 95% N2/5% CO2. Islet viability was determined by fluorscein diacetate/ethidium bromide staining at intervals varying from 2.5 h to 7 days; blood gas measurements were obtained on media samples at the end of selected incubation intervals. Rat islets underwent near-total necrosis and fragmentation in <24 h; occasional viable single cells could be identified until about 72 h. On the other hand, the fish islets showed no loss of viability until about 72 h when some showed mild central necrosis. Even at 7 days, all fish islets appeared roughly 50% viable. Fish islets cultured under hypoxic conditions for 72 h (media, pO2 = 27.8 mmHg) and then transplanted into streptozotocin-diabetic athymic nude mice were viable (6/6) but showed some diminished function (3/6) over a 25-day follow-up period. Our results suggest that tilapia islets will survive and function at lower oxygen tensions than mammalian islets.

Random protein-creatinine ratio for the quantitation of proteinuria in pregnancy.

OBJECTIVE: To compare random urine protein-creatinine ratios with 24-hour urine protein excretion rates in patients hospitalized with hypertensive disorders in pregnancy. METHODS: All hospitalized, hypertensive patients requiring 24-hour urine protein excretion collections were eligible for the study. During the 24-hour urine collection a separate 2-mL aliquot was taken for a protein and creatinine determination. RESULTS: Seventy-one samples were collected from patients with the following diagnoses: gestational hypertension (n = 56), preexisting hypertension and superimposed gestational hypertension (n = 11), and syndrome of hemolysis, elevated liver enzymes and low platelets (n = 4). The correlation coefficient between the random protein-creatinine ratio and the 24-hour urine protein excretion was 0.94. Calculated excretion rates with at least 300 mg protein in 24 hours had a sensitivity of 0.93, specificity of 0.90, and positive and negative predictive values of 0.87 and 0.95, respectively. For those samples with calculated excretion rates at least 5 g protein in 24 hours, the sensitivity was 1.00, specificity was 0.99, and positive and negative predictive values were 0.75 and 0.99, respectively. CONCLUSION: In nonambulatory hypertensive pregnant patients, there is a strong correlation between random voided protein-creatinine ratios and 24-hour urine protein excretions.

From oxygen content to pulse oximetry: completing the picture in the newborn.

In recent years clinicians caring for sick preterm infants have come to depend on pulse oximetry to avoid hyperoxia, which means assuming saturation values for critical levels of oxygen tension. This prediction is made difficult by the shape of the haemoglobin-oxygen dissociation curve at critical values for arterial pO2 and by the effects of changes in acid-base balance on p50. Combined blood gas and co-oximetry measurements can be used to determine critical limits for pulse oximetry. Fetal haemoglobin has slightly different light absorption characteristics from adult haemoglobin. To adjust for this, adult and fetal matrices are available in the OSM 3 HEMOXIMETER (Radiometer Medical A/S, Denmark) but the measurement requires an extra preliminary step to estimate fetal haemoglobin concentration. We sought to determine the importance of this extra procedure for measuring the saturation of newborn blood, and to determine whether the adult or fetal mode should be used for determining saturation for comparison with pulse oximeters. We measured the effect of the correction for fetal haemoglobin by obtaining absorbances from the co-oximeter and multiplying them by the adult and fetal matrices. We demonstrated that, at 90% saturation, failure to use the fetal correction in the presence of high levels of fetal haemoglobin result in a 4% overestimate of saturation, with resultant underestimation of the safe range for pulse oximetry. Published values for extinction coefficients for fetal and adult blood at wavelengths used by pulse oximeters are inconsistent, but it appears that fetal haemoglobin does not bias pulse oximetry readings. Determining saturation limits by co-oximetry for use with pulse oximeters in preterm infants requires the description of the haemoglobin-oxygen dissociation curve with the correction for fetal haemoglobin.

Enzymatic method for phenylketonuria screening using phenylalanine dehydrogenase.

An enzymatic method using phenylalanine dehydrogenase (PheDH;EC 1.4.1.-) for the determination of phenylalanine in blood-spot specimens has been developed for the Cobas Bio centrifugal analyser. Method accuracy was established by correlation of results from blood spots with phenylalanine values obtained by quantitative aminoacid analysis on simultaneously collected plasma specimens. The phenylalanine dehydrogenase method demonstrated linearity to 2500 mumol/L and had recoveries of 89.4 +/- 4.6% (mean +/- SEM). The between-run precision using blood-spot specimens was 9.8% at 285 mumol/L. In the context of a routine newborn screening program, the enzymatic method was found to have a lower false-positive rate (1% vs 3%) when evaluated against the classical fluorimetric Autoanalyser method.

Ethanolaminuria: a non-specific laboratory finding in the seriously ill infant.

Ethanolamine is a compound that is frequently seen in urinary amino acid analysis. Although there is a single report of increased ethanolamine excretion associated with a distinctive storage disease in two siblings, the significance of ethanolaminuria is not known. We measured urinary ethanolamine/creatinine ratios in 102 hospitalized infants under two years of age and examined the clinical correlations in six cases whose ratios were more than five-fold higher than the maximum value for the established reference range. We found that ethanolamine excretion was strongly dependent on age even when the data were corrected for significant positive skewing. Increased ethanolamine excretion was common in the first week of life, but five of the six cases we specifically studied were characterized by progressive, debilitating illness and three of the six patients subsequently died. Although we found no evidence of a storage disorder, we did note that there was evidence of neuronal white matter degeneration in most but not all cases. Thus, ethanolaminuria appears to be a non-specific sign of severe neurological disease rather than a distinctive feature of a specific inborn error of metabolism.

Uptake of lysosomal enzymes by human fibroblasts: lack of uptake of fungal or plant glycosidases in comparison with a mammalian enzyme.

alpha-Galactosidase from human placenta was actively taken up by cultured fibroblasts from patients with Fabry's disease whereas the enzyme from the fig was not absorbed. alpha-Glucosidase from two microbiological sources. A. fumigatus and A. niger, was not taken up by cultured fibroblasts from patients with Pompe's disease.

Hyperprolinemia type II: evidence of the excretion of 3-hydroxy delta 1-pyrroline 5-carboxylic acid.

We report the identification of delta 1-pyrroline 3-hydroxy 5-carboxylic acid (hydroxy PCA) in a previously reported patient with hyperprolinemia Type II. This compound had been called pseudo PCA in a previous report.