Torleif Trydal

Reference intervals and age and gender dependency for arterial blood gases and electrolytes in adults.

Abstract Background: Although results from blood gas analyzers are frequently used in clinical work surprisingly few and small studies have examined reference intervals for arterial blood gases and acid-base status. We have established reference values based on a large group of healthy people with a wide age distribution. Methods: A group of medical students (n=182) aged 20–32 years old and a group of health professionals aged 21–76 years were used in this study. Arterial samples were analyzed on the blood gas analyzer ABL from RadiometerTM. Age and gender dependency was examined for all analytes and reference intervals were calculated non-parametrically. Results: Females had significantly higher pH and lower PaCO2 (partial pressure of carbon dioxide in an arterial sample), base excess (BE, standard, extra cellular fluid), plasma standard and actual HCO3, when compared to males (p<0.01). However, the differences were minor and common reference intervals were therefore also determined, generally at the same level as previously published. The lactate values were similar among the genders but with a high upper limit of 2.5 mmol/L. The non-smoker group of females and males had similar PaO2 values (partial pressure of oxygen in an arterial sample). However, an age dependent effect was found and PaO2 decreased by 0.29 kPa per decade (confidence interval of slope –0.11 to –0.47 kPa). Electrolytes and anion gap results depicted smaller differences from previous published reference intervals for sodium (136–141 mmol/L) and anion gap (10–16 mmol/L, with potassium included or 6–12 mmol/L without potassium). Conclusions: Reference intervals for analytes on modern blood gas analyzers were established on a large group of healthy people. Gender and age dependency is generally without clinical importance, except for a lower PaCO2 in women and a decreasing PaO2 with higher age.

Comparison of the transcutaneous bilirubinometers BiliCheck and Minolta JM-103 in preterm neonates

Aim:  To investigate the trueness and uncertainty of two transcutaneous bilirubinometers BiliCheck and Minolta JM‐103 in preterm infants; establish cut‐off values for the transcutaneous bilirubin (TcB) level, indicating the need for total serum bilirubin (TsB) measurement; and estimate how many blood samples could be saved.

Effect of phototherapy with turquoise vs. blue LED light of equal irradiance in jaundiced neonates

Background:Blue light with peak emission around 460 nm is the preferred treatment of neonatal hyperbilirubinemia. However, studies using fluorescent light tubes have suggested that turquoise light with peak emission at 490 nm may be more efficient. At present, the predominant light source for phototherapy is light emitting diodes (LEDs). Hence, the aim of this study was to compare the bilirubin-reducing effect in jaundiced neonates treated either with turquoise or with blue LED light with peak emission at 497 or 459 nm, respectively, with equal irradiance on the infants.Methods:Infants with gestational age ≥33 wk and uncomplicated hyperbilirubinemia were randomized to either turquoise or blue LED light and were treated for 24 h. The mean irradiance footprint at skin level was 5.2 × 1015 and 5.1 × 1015 photons/cm2/s, respectively.Results:Forty-six infants received turquoise light and 45 received blue light. The median (95% confidence interval) decrease of total serum bilirubin was 35.3% (32.5; 37.3) and 33.1% (27.1; 36.8) for infants treated with turquoise and blue lights, respectively. The difference was nonsignificant (P = 0.53). The decrease was positively correlated to postnatal age and negatively to birth weight.Conclusion:Using LED light of equal irradiance, turquoise and blue lights had equal bilirubin-reducing effect on hyperbilirubinemia of neonates.

Evaluation of back scatter interferometry, a method for detecting protein binding in solution.

Back Scatter Interferometry (BSI) has been proposed to be a highly sensitive and versatile refractive index sensor usable for analytical detection of biomarker and protein interactions in solution. However the existing literature on BSI lacks a physical explanation of why protein interactions in general should contribute to the BSI signal. We have established a BSI system to investigate this subject in further detail. We contribute with a thorough analysis of the robustness of the sensor including unwanted contributions to the interferometric signal caused by temperature variation and dissolved gasses. We report a limit of the effective minimum detectability of refractive index at the 10(-7) level. Long term stability was examined by simultaneously monitoring the temperature inside the capillary revealing an average drift of 2.0 × 10(-7) per hour. Finally we show that measurements on protein A incubated with immunoglobulin G do not result in a signal that can be attributed to binding affinities as otherwise claimed in literature.

Bilirubin isomer distribution in jaundiced neonates during phototherapy with LED light centered at 497 nm (turquoise) vs. 459 nm (blue).

Background:Phototherapy using blue light is the treatment of choice worldwide for neonatal hyperbilirubinemia. However, treatment with turquoise light may be a desirable alternative. Therefore, the aim of this randomized, controlled study was to compare the bilirubin isomer distribution in serum of jaundiced neonates after 24 h of therapy with narrow-band (LED) light centered at 497 nm (turquoise) vs. 459 nm (blue), of essentially equal irradiance.Materials:Eighty-three neonates (≥33 wk gestational age) with uncomplicated hyperbilirubinemia were included in the study. Forty neonates were exposed to light centered at 497 nm and 43 infants with light centered at 459 nm. Irradiances were 5.2 × 1015 and 5.1 × 1015 photons/cm2/s, respectively.Results:After 24 h of treatment no significant differences in serum concentrations of total bilirubin isomers and Z,Z-bilirubin were observed between the 2 groups. Interestingly, concentrations of Z,E-bilirubin, and thus also total bilirubin isomers formed during therapy, were highest for infants receiving light centered at 459 nm, while the concentration of E,Z-bilirubin was highest for those receiving light centered at 497 nm. No significant difference was found between concentrations of E,Z-lumirubin.Conclusion:Therapy with LED light centered at 497 nm vs. 459 nm, applied with equal irradiance on the infants, resulted in a different distribution of bilirubin isomers in serum.

Acute Favism: Methemoglobinemia May Cause Cyanosis and Low Pulse Oximetry Readings

Persons with glucose-6-phosphate dehydrogenase (G6PD) deficiency may suffer episodes of acute hemolysis triggered by infection, drugs, and chemicals [1]. Acute favism after ingestion of fava beans is a special type [2]. Recently, two cases with clinically manifest methemoglobinemia, a hitherto unrecognized feature, were reported [3, 4]. We saw two similar cases with low-pulse oximeter saturation (SpO2) misinterpreted as hypoxia.