The aim of this study was to test the hypothesis that differences in oxygen tension (PO 2 ) and carbon dioxide tension (PCO 2 ) values from measurements performed on different blood gas analysers in different laboratories are clinically insignificant.Samples of fresh whole human tonometered blood (PO 2 8.1 kPa (60.8 mmHg); PCO 2 5.3 kPa (39.9 mmHg)) were placed in airtight glass syringes and transported in ice-water slush. Blood gas analysis was performed within 3.5 h by 17 analysers (10 different models) in 10 hospitals on one day.The mean of the differences between the measured and target values was -0. We conclude that the variability in measurement of blood gas values among different blood gas analysers, although negligible, depends much more on inter-than intra-instrument variation, both for oxygen tension and carbon dioxide tension. Technical improvements and adequate quality control programmes, including tonometry, may explain why the variability in blood gas values depends mainly on errors in the pre-analytical phase.
The pharmacokinetics of intradural morphine used for major abdominal surgery were evaluated. Lumbar spinal fluid and plasma concentrations were measured at intervals after morphine 0.05 mg/kg had been injected intradurally in 21 patients scheduled for elective abdominal aortic surgery. The CSF morphine concentrations were fitted by a biexponential function. A non-compartmental model based on statistical moment theory was used for calculating the intradural morphine disposition. Mean residence time was 137 +/- 54.9 minutes, mean initial volume of distribution 15 +/- 5.49 ml, mean volume of distribution at steady-state 42 +/- 18.25 ml and mean clearance 0.34 +/- 0.18 ml/min (0.02 +/- 0.01 L/h). The moments of the morphine concentration-time curves and the pharmacokinetic parameters varied between the patients. They were not significantly different with regard to morphine dosage, or patient sex or age. Free morphine could not be detected in plasma. Morphine-3-glucuronide appeared in plasma at 5 minutes, increased to a maximum at 240 minutes and fell below the detection limit at about 16 hours after morphine administration. Possible clinical causes of interindividual variations in the CSF morphine concentrations and the pharmacokinetics of intradural morphine are discussed.
Winckers, Teunissen, Van den Camp, Maas and Veefkind: Comparative study of three blood gas electrode systems 175 J. Clin. Chem. Clin. Biochem. Vol. 16, 1978, pp. 175-185 A Comparative Study of the Electrode Systems of Three pH and Blood Gas ApparatusBy E. K. A. Winckers, A. J. Teunissen,R. A. M. Van den Camp, A. H (Received February 10/August 26, 1977) Summary: We present a comparative evaluation of the electrode systems of three modern blood gas analysers: IL-413, ABL-1 and AVL-937C.The response curves, accuracy and precision of the pH-, pCO 2 -and pO 2 -electrodes were established with tonometered blood and buffer solutions.pH values (range 6.8-7.8) measured on the AVL deviate (-0.03 pH for blood and + 0.03 pH for buffer) from those of BMS2 Mk2; whereas on the IL and ABL analysers the pH values deviate by not more than 0.01 pH. The standard deviation was better than 0.005 pH.pCO 2 values of blood and buffer (range 14-106 mm Hg) deviate from the calculated tonometer values by quantities ranging from 3 to 10 mm Hg. The average precision (CV) 1 ) of the pCO 2 measurement on each analyser was better than 1.8%.pO 2 values of blood (range 0-130 mm Hg) did not differ by more than 3 mm Hg from the calculated values. Above 130 mm Hg a linear negative increasing difference was seen.For buffer solutions a linear relationship between pO 2 difference and pO 2 value was found over the whole range from zero up to 642 mm Hg: a positive difference below and a negative difference above the pO 2 of the previous calibration; if the calibration pO 2 is higher, the sample pO 2 is shifted to a higher value.The average precision of the pO 2 measurements was better than 3 %. In the (patho)-physiological range the three instruments may provide suitable results for the clinician. Suggestions are made for standardization and improvement of the electrode systems. Vergleichende Untersuchung der Elektrodensy st erne von drei pH-und Blutgas-MeßgerätenZusammenfassung: Eine vergleichende Bewertung der Elektrodensysteme von drei modernen Blutgasanalysatoren (11-413, ABL-1 > AVL-937C) wird vorgestellt.Ansprechbarkeit, Richtigkeit und Zuverlässigkeit der pH-, pCO 2 -und pO 2 -Elektroden wurden mit tonometriertem Blut und Pufferlösungen festgestellt.Die am AVL gemessenen pH-Werte (Bereich 6,8) weichen für Blut um -0,03 und für Puffer um + 0,03 von den mit dem BMS2 Mk2 gemessenen ab, während sie am IL und ABL nicht mehr als 0,01 pH abweichen. Die Standardabweichung war besser ajs 0,005 pH. pCO 2 -Werte von Blut und Puffer (Bereich 14-106 mm Hg) weichen von den berechneten Tonometer-Werten um 3 bis zu 10 mm Hg ab. Der Mittelwert der Genauigkeit (VK) der pCO 2 -Messung an jedem Gerät war besser als 1,8%. Für Pufferlösungen wurde eine lineare Beziehung zwischen p0 2 -Differenz und pO 2 -Wert über den gesamten Bereich von 0 bis 642 mm Hg gefunden: eine positive Differenz unterhalb und eine negative oberhalb des pO 2 des letzten Kalibriergases; wenn das p0 2 des Kalibriergases höher ist, weicht der pO 2 -Wert der Probe zu einem höheren Wert hin...
In response to the need for an adequate quality-control system for blood-pH and blood-gas analyzers, we investigated the practical application of ampouled phosphate-bicarbonate-chloride solutions tonometered with mixtures of carbon dioxide, oxygen, and nitrogen. This system offers three discrete sets of pH, pCO2, AND PO2 values, which are consistent with normal and pathophysiologically high and low values. The stated values were based on the U.S. National Bureau of Standards scale for pH and on gas analysis for pCO2 and pO2. Influence of temperature, air contact, calibration gas, and storage was established. Internal and external quality control by means of these ampoules is presented. The system is stable, accurate, precise, and suitable for simultaneous quality control of pH, pCO2, and pO2 measurements.
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