Blood gases calibration

For a detailed discussion of the art of sample handling and data acquisition for blood gas measurements, see National Committee for Clinical Laboratory Standards. Blood gas pre-analytical considerations specimen collection, calibration, and controls Proposed Guideline. NCCLS publication C27-P, Villanova, Pennsylvania, NCCLS, 1985... 

The precautions cited for large refillable gas cylinders also apply to small cylmders that are not refillable. Propane cylinders of the type frequently secured to a flame photometer and cyfinders of calibrating gases for blood gas equipment... 

Single-use devices for blood gas and other critical care measurements are also available through optical sensors or optodes (see Chapters 4 and 27). The Osmetech OPTI Critical Care Analyzer (Figure 12-8) and the Radiometer NPT 7 are examples of this type of technology. The advantages of optical systems compared with electrochemical transducers include the fact that they do not have to be calibrated to correct for electrode drift, and therefore the sensors are calibrated at the time of manufacture. ... 

Mollard J-E Single phase calibration for blood gas and electrolyte analysis. In D Orazio P, ed. Preparing for critical care analyses in the 2P century. Proceedings of the 16 International Symposium. Washington AACC Press, 1996. 

Consider a calibrator gas certified to contain 15% O2 (L/L or mol/mol) and 5% CO2, the remainder being N. The mole fractions (or F) of the gases in the dry mixture are 0.15,0.05, and 0.80, respectively. This mixture, after saturation with water vapor at 37 °C (to mimic a patient s blood or alveolar air), is introduced into a blood gas instrument s measuring chamber (held at 37 °C to mimic a patient s body temperature) for the purpose of calibrating the instrument for subsequent measurements of gases in patients samples. If the local barometric pressure, P(Amb), on this occasion is 747 mmHg, then the humidified calibrator gas is present in the chamber at ambient, barometric pressure, such that... 

The instrument (see Figure 27-4) is designed so that a manually or microprocessor actuated valve (V) admits calibrator gases, standard buffers, or a sample to a small chamber (C) maintained by a fluid or metal bath (B) to a constant temperature of 37 C 0.1 C, Measuring and reference electrodes (E) protrude into this chamber. In the pH calibration phase of the instrument, high pH standard buffer and low pH standard buffer are alternately admitted into the chamber and electronic responses of the upper and lower limits of a linear pH curve are established. In the gas calibration phase, gas mixtures with high and low fractional concentrations of O2 and CO2 are alternately admitted into the chamber and electronic responses of the upper and lower limits of linear PO2 and PCO2 curves are set. In the measurement phase, an anaerobically collected blood sample is admitted. 

Liquid-Gas Difference of a PO2 Electrode When calibration gases are used to standardize a system, a particular property of the PO2 electrode needs to be considered. This property is called the liquid-gas or blood-gas difference. 

Eichhom J H, Moran R F and Cormier A D 1985 Blood Gas Pre-Analytical Considerations Specimen Collection, Calibration, and Controls C27-P (Villanova National Committee for Clinical Laboratory Standards) Itano M 1983 CAP blood gas survey—1981 and 1982 Am. J. Clin. Pathol. 80 554-62... 

The blood gas cell can be modified to optimize either the measurements of partial pressures or contents. Decreasing the permeability of the membrane by an order of magnitude will effectively reduce all boundary layer effects, allowing a linear calibration for P02. At the other extreme, increasing the membrane permeability (e.g., silicone rubber membranes) would permit a rapid depletion of the blood gases, facilitating content measurements. 

Analyses were made for oxygen content in a Van Slyke-Neill constant-volume blood gas apparatus. The transfer pipet was calibrated for content and retention on the walls of whole blood or concentrated oxyhemoglobin solution corresponding to conditions of use the gas pipet was also calibrated for volume. Correction was made for dissolved oxygen on the assumption that the quantity dissolved is proportional to the water present in the solution. 

Calibration for Blood Gas Determination by Gas Chromatography Anal. Chem. 37(7) 924-925 (1965) CA 63 4633b... 

Figure 5.34 Temporal traces of the calibrated GluCath intravascular continuous glucose sensor for two subjects with type 1 diabetes compared with results from a ABL Radiometer 805 Blood Gas Analyzer.

DISCUSSION. Figure 10.11 shows the separation of a group of gases from blood. The procedure described depends on complete equilibration between the gas and liquid in the syringe. The period to achieve equilibration depends on the gas, and can be as little as 1 min for acetone and as much as 30 min for sulfur hexafluoride. Linear calibration curves can be obtained when peak height is plotted against gas concentration for either the flame ionization or electron capture detector. The reproducibility (n = 10) for ethane gave a standard deviation of 23% of the mean concentration while it was 2.3% for halothane and 1.8% for ether. 

NCCLS. Gas preanalytical considerations specimen collection, calibration, and controls approved guideline, C27-A-Blood. Wayne, Pa, 1993. 

Using CO2 electrodes - applications include measurement of blood PCO2 end in enzyme studies where C02 is utilized or released calibration of the electrode is accomplished using 5% v/v and 10%v/v mixtures of C02 in an inert gas equilibrated against the measuring solution. 

You prepare a calibration curve for the measurements of blood ethanol by gas chromatography. The recorded peak area as a function of concentration is ... 

For C02 the solution to the MTE predicts that a simple proportionality relation can be used to relate the water calibration to the determination of Pco2 ln blood. The circles in Figure 4 represent blood samples equilibrated at four different Pco2 s- The corresponding water samples are represented by the crosses. The dashed line is the predicted gas phase output of the BGC. The linear correlation exceeded 0.98 for the water and the blood data. The standard error of measurement for blood was 0.57 mm Hg and 0.42 mm Hg for the water data. 

The value of the partial pressure measured at the skin surface depends in a complex way on blood partial pressure, constitution of the skin, local perfusion, metabolism in the associated tissue, cardiac output, and application temperature. An increased temperature of 43 °C raises the gas permeability and expands the capillary vessels of skin which are filled with more artial blood. The local hyperemia has the disadvantage of limiting the application time at a certain site. Assuming stable circulation conditions, transcutaneously measured values correlate with arterial partial pressure by a factor of 1.2 (neonates) to 1.0 (small children) [1]. The measured value for adults proved to be very unreliable. In the case of unstable conditions or shock with a reduction of peripheral blood flow, the transcutaneous value drops very early. Inconvenience in routine use is caused by long preparation times of the sensor, the need for periodic membrane changes, the long run-in time of freshly prepared sensors, the necessity for periodic calibrations and the slow response time to changes in partial pressure. 

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