Differences in PO2 and PCO2 between arterial and arterialized earlobe samples

Abstract

Differences in PO 2 and PCO 2 between arterial and arterialized earlobe samples. A. Sauty, C. Uldry, L-F. Debétaz, P. Leuenberger, J-W. Fitting. ©ERS Journals Ltd 1996. ABSTRACT: Arterialized ear lobe blood samples have been described as adequate to gauge gas exchange in acute and chronically ill patients. It is a safe procedure, usually performed by medical technicians. We have conducted a prospective study to verify the validity of this method.One hundred and fifteen consecutive adult patients were studied. Blood samples were drawn simultaneously from arterialized earlobe and radial artery. Values of partial pressure of oxygen (PO 2 ) and of carbon dioxide (PCO 2 ) were measured by means of blood gas electrodes.The correlation coefficients between the two samples were 0.928 for PO 2 and 0.957 for PCO 2 values. In spite of a highly significant correlation, the limits of agreement between the two methods were wide for PO 2 . Earlobe values of PO 2 were usually lower than arterial values, with larger differences in the range of normal arterial PO 2 . On the other hand, the error and the limits of agreement were smaller for PCO 2 .We conclude that, in adult patients, arterialized earlobe blood PO 2 is not a reliable mirror of arterial PO 2 . Eur Respir J., 1996, 9: 186-189 Blood gas values can be measured using arterialized earlobe blood samples, instead of arterial samples, in order to gauge pulmonary gas exchange in acute or chronically ill patients. This method, described many years ago [1], is a simple and safe procedure which can be performed by medical technicians. Comparing values for partial pressure of oxygen (PO 2 ) and of carbon dioxide (PCO 2 ) from arterialized earlobe blood samples with arterial blood samples, several authors have concluded that the earlobe site was suitable for routine clinical purposes [1][2][3][4][5][6][7][8][9]. This idea was again advocated by two recent studies. PITKIN et al. [10] compared PO 2 , PCO 2 , and pH values from 40 blood samples simultaneously drawn from the radial artery and hyperaemic earlobe. Using the method of BLAND and ALTMAN [11] for the assessment of agreement, these authors also concluded that arterialized earlobe blood gas values were accurate enough to be used in clinical application. Finally, DAR et al. [12] reported that earlobe sampling was significantly less painful than arterial sampling in 55 patients, whereas blood gas values were not different with the two techniques.For several years, the arterialized earlobe technique has been the standard practice for measuring arterial blood gases in our pulmonary function laboratory. However, in some instances, we have noticed a marked discrepancy between arterial and relatively lower arterialized earlobe values of PO 2 . We, therefore, conducted a prospective study to compare arterial and arterialized earlobe blood samples in 115 consecutive adult patients. Material and methodsOur study group included 115 consecutive adult patients investigated in our pulmonary function laboratory for various conditions. No...

Blood Chemistry, Acid-Base, Electrolyte, Blood Lactate Metabolism and Sleep at 3480 m in Mountain Marathon Runners

“…Arterialized earlobe blood is said to be more suitable for clinical assessment of arterial pO 2 only for values < 60 mm Hg and less suitable for higher values due to underestimation of the real value [21]. Overall, our study seems to confirm that the techniques we used for evaluating most of the changes in blood chemistry, acid-base equilibrium [21], electrolyte and blood lactate are suitable for clinical assessment and for metabolic research at high altitude.…”

“…Overall, our study seems to confirm that the techniques we used for evaluating most of the changes in blood chemistry, acid-base equilibrium [21], electrolyte and blood lactate are suitable for clinical assessment and for metabolic research at high altitude.…”

“…Recently, arterialized earlobe blood sampling has been demonstrated a simple and safe method suitable for clinical, laboratory molecular evaluation. The earlobe blood sampling technique has been reported to be less painful than the more correct arterial sampling and is advocated as a reliable method for arterial blood gas determination and as standard practice for acid-basic balance analysis [21]. The validity of arterialized earlobe blood samples…”

Is arterialized earlobe blood PO2 an acceptable substitute for arterial blood PO2?

“…We read with great interest the paper by SAUTY et al [1] in the February issue of the Journal. They found that arterialized earlobe blood samples are in good agreement with arterial blood samples for carbon dioxide tension (PCO 2 ) but not for oxygen tension (PO 2 ), and rightly state that "arterialized earlobe blood PO 2 is not a reliable mirror of arterial PO 2 " in adults patients.…”

Capillary PO2 does not adequately reflect arterial PO2 in hypoxemic COPD patients

“…2 However, it is less useful in the acute setting because an adequate vasodilatation needs to be ensured, which typically lasts for at least 10 minutes. 1,2,[5][6][7] Different trials have evaluated the agreement between ABG and CBG in terms of PO 2 measurements, with conflicting results; whereas one trial reported close agreement between ABG-versus CBG-derived values over a wide range of PO 2 values, 7 other trials showed wide limits of agreement (LOA). 8,9 A 2007 meta-analysis comparing ABGs to CBGs emphasized that capillary PO 2 (P c O 2 ) (earlobe sampling) may be an appropriate replacement for arterial PO 2 (P a O 2 ); 2 however, the authors also pointed out that CBG might not be appropriate if precision is required, based on the fact that the residual standard error (SE) in the regression equation was 6 mmHg.…”