Indian Journal of Critical Care Medicine

Register      Login

SEARCH WITHIN CONTENT

FIND ARTICLE

Volume / Issue

Online First

Archive
Related articles

VOLUME 12 , ISSUE 3 ( September, 2008 ) > List of Articles

RESEARCH ARTICLE

Prediction of arterial blood gas values from arterialized earlobe blood gas values in patients treated with mechanical ventilation

Mohammadreza Safavi, Azim Honarmand

Keywords : Arterialized earlobe blood gas, critically illness, mechanical ventilation

Citation Information : Safavi M, Honarmand A. Prediction of arterial blood gas values from arterialized earlobe blood gas values in patients treated with mechanical ventilation. Indian J Crit Care Med 2008; 12 (3):96-101.

DOI: 10.4103/0972-5229.43677

License: CC BY-ND 3.0

Published Online: 01-09-2008

Copyright Statement:  Copyright © 2008; Jaypee Brothers Medical Publishers (P) Ltd.


Abstract

Background/Objective: Arterial blood gas (ABG) analysis is useful in evaluation of the clinical condition of critically ill patients; however, arterial puncture or insertion of an arterial catheter may sometimes be difficult and cause many complications. Arterialized ear lobe blood samples have been described as adequate to gauge gas exchange in acute and chronically ill pediatric patients. Purpose: This study evaluates whether pH, partial pressure of oxygen (PO 2), partial pressure of carbon dioxide (PCO 2), base excess (BE), and bicarbonate (HCO 3) values of arterialized earlobe blood samples could accurately predict their arterial blood gas analogs for adult patients treated by mechanical ventilation in an intensive care unit (ICU). Setting: A prospective descriptive study Methods: Sixty-seven patients who were admitted to ICU and treated with mechanical ventilation were included in this study. Blood samples were drawn simultaneously from the radial artery and arterialized earlobe of each patient. Results: Regression equations and mean percentage-difference equations were derived to predict arterial pH, PCO 2, PO 2, BE, and HCO 3 -values from their earlobe analogs. pH, PCO 2, BE, and HCO 3 all significantly correlated in ABG and earlobe values. In spite of a highly significant correlation, the limits of agreement between the two methods were wide for PO 2. Regression equations for prediction of pH, PCO 2, BE, and HCO3- values were: arterial pH (pHa) = 1.81+ 0.76 x earlobe pH (pHe) [r = 0.791, P < 0.001]; PaCO 2 = 1.224+ 1.058 x earlobePCO 2 (PeCO 2) [r = 0.956, P < 0.001]; arterial BE (BEa) = 1.14+ 0.95 x earlobe BE (BEe) [r= 0.894, P < 0.001], and arterial HCO 3 - (HCO 3 -a) = 1.41+ earlobe HCO 3 (HCO 3 -e) [r = 0.874, P < 0.001]. The predicted ABG values from the mean percentage-difference equations were derived as follows: pHa = pHe x 1.001; PaCO 2 = PeCO 2 x 0.33; BEa = BEe x 0.57; and HCO 3 -a = HCO 3 -e x 1.06. Conclusions: Arterialized earlobe blood gas can accurately predict the ABG values of pH, PCO 2, BE, and HCO 3 - for patients who do not require regular continuous blood pressure measurements and close monitoring of arterial PO 2 measurements.


PDF Share
  1. Arterial puncture and cannulation. In: Roberts JR, Hedges JR, editors. Clinical procedures in emergency medicine, 3rd ed. Philadelphia: WB Saunders; 1998. p. 308-22.
  2. Venous pH can safely replace arterial pH in the initial evaluation of patients in the emergency department. Emerg Med J 2001;18:340-2.
  3. Small blood samples from earlobe puncture: A substitute for arterial puncture. Lancet 1965;2:315-7.
  4. Blood gas measurement during exercise: A comparative study between arterialized earlobe sampling and direct arterial puncture in adults. Eur Respir J 1998;11:712-5.
  5. Arterialised earlobe blood gas analysis: An underused technique. Thorax 1994;49:364-6.
  6. Clinical use and limitations of arterialized capillary blood for PO2 determination. Am Rev Respir Dis 1968;98:653-7.
  7. Arterialized earlobe blood samples for blood gas tensions. Br J Dis Chest 1976;70:263-8.
  8. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1:307-10.
  9. Differences in PO2 and PCO2 between arterial and arterialized earlobe samples. Eur Respir J 1996;9:186-9.
  10. Is arterialized earlobe blood PO2 an acceptable substitute for arterial blood PO2? Eur Respir J 1996;9:1329-30.
  11. Capillary blood gases in a pediatric intensive care unit. Crit Care Med 2000;28:224-6.
  12. The usefulness of peripheral venous blood in estimating acid-base status in acutely ill patients. Ann Emerg Med 1985;14:845-9.
  13. Comparison of simultaneously obtained arterial and capillary blood gases in pediatric intensive care unit patients. Crit Care Med 1997;25:1904-8.
  14. Capillary refilling (skin turgor) in the assessment of dehydration. Am J Dis Child 1991;145:296-8.
  15. Clinical decisionmaking based on venous versus capillary blood gas values in the well-perfused child. Ann Emerg Med 1999;34:58-63.
  16. Assessing acid-base status in circulatory failure: Differences between arterial and venous blood. N Engl J Med 1989;320:1312-6.
  17. Comparison of pH, carbon dioxide tension, standard bicarbonate and oxygen tension in capillary blood and in arterial blood during the neonatal period. Acta Pediatr Scand 1967;56:10-6.
  18. Use of capillary blood in measurement of arterial PO2. Br Med J 1968;3:640-3.
  19. Earlobe blood samples for blood gas analysis at rest and during exercise. Br J Dis Chest 1971;65:58-64.
  20. Capillary versus arterial blood gases. Anesth Analg 1973;52:724-7.
  21. Measurement of blood gases. Eur Respir J 1989;2:160s-3s.
  22. Value of capillary blood gas analysis in the management of acute respiratory distress. Am Rev Respir Dis 1976;113:707-8.
  23. Arterial versus capillary sampling for analysing blood gas pressures. BMJ 1995;309:24-5.
  24. Clinical sequelae from arterial needle puncture, cannulation and incision. Circulation 1967;35:1118-23.
PDF Share
PDF Share

© Jaypee Brothers Medical Publishers (P) LTD.