Anesthesiology, V 120 • No 2 416 February 2014 P ATIENTS with acute respiratory distress syndrome and chronic obstructive pulmonary disease show a marked increase in ventilatory dead space, 1 which impairs the clearance of carbon dioxide. To maintain physiological blood pH and carbon dioxide partial pressure (pCO 2 ) values, these patients require an increase in minute ventilation, 2 fos- tering ventilator-induced lung injury. 3 Combined extracorporeal carbon dioxide removal (ECCO 2 R) and low tidal volume ventilation have been pro- posed as a mean to reduce the risk of ventilator-induced lung injury. 4–7 To achieve a signifcant ECCO 2 R (i.e., 50% What We Already Know about This Topic • Extracorporeal carbon dioxide removal may help decrease the need for mechanical ventilation What This Article Tells Us That Is New • Lactic acid infusion enhances low-fow extracorporeal carbon dioxide removal; this system, therefore, may be of great utility in critically ill patients Copyright © 2013, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins. Anesthesiology 2014; 120:416-24 ABSTRACT Background: Extracorporeal carbon dioxide removal has been proposed to achieve protective ventilation in patients at risk for ventilator-induced lung injury. In an acute study, the authors previously described an extracorporeal carbon dioxide removal technique enhanced by regional extracorporeal blood acidifcation. Te current study evaluates efcacy and feasibility of such technology applied for 48 h. Methods: Ten pigs were connected to a low-fow veno-venous extracorporeal circuit (blood fow rate, 0.25 l/min) including a membrane lung. Blood acidifcation was achieved in eight pigs by continuous infusion of 2.5 mEq/min of lactic acid at the membrane lung inlet. Te acid infusion was interrupted for 1 h at the 24 and 48 h. Two control pigs did not receive acidifca- tion. At baseline and every 8 h thereafter, the authors measured blood lactate, gases, chemistry, and the amount of carbon diox- ide removed by the membrane lung (VCO 2 ML). Te authors also measured erythrocyte metabolites and selected cytokines. Histological and metalloproteinases analyses were performed on selected organs. Results: Blood acidifcation consistently increased VCO 2 ML by 62 to 78%, from 79 ± 13 to 128 ± 22 ml/min at baseline, from 60 ± 8 to 101 ± 16 ml/min at 24 h, and from 54 ± 6 to 96 ± 16 ml/min at 48 h. During regional acidi fcation, arterial pH decreased slightly (average reduction, 0.04), whereas arterial lactate remained lower than 4 mEq/l. No sign of organ and erythrocyte damage was recorded. Conclusion: Infusion of lactic acid at the membrane lung inlet consistently increased VCO 2 ML providing a safe removal of carbon dioxide from only 250 ml/min extracorporeal blood fow in amounts equivalent to 50% production of an adult man. (ANESTHESIOLOGY 2014; 120:416-24) This article is featured in “This Month in Anesthesiology,” page 1A. Corresponding article on page 266. Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org). Figure 3 was pro- vided by Annemarie B. Johnson, C.M.I., Medical Illustrator, Vivo Visuals, Winston-Salem, North Carolina. Preliminary data were presented during the: 2012 American Thoracic Society International Conference: San Francisco, CA, May 18, 2012; XXV European Society of Intensive Care Medicine, Lisbon, Portugal, October 16, 2012; and XXIII Simposio Mostra Anestesia Rianimazione E Terapia Intensiva, Milan, Italy, May 9, 2012. Submitted for publication May 2, 2013. Accepted for publication September 9, 2013. From the Dipartimento di Scienze della Salute, Università di Milano-Bicocca, Ospedale San Gerardo Nuovo dei Tintori, Monza, Italy (A.Z., P.M., S.R., V.S., M.G., D.F., N.P., and A.P.); Dipar- timento di Patologia animale, Igiene e Sanità pubblica veterinaria, sez. di Biochimica e Fisiologia, Università degli studi di Milano, Milan, Italy (F.P. and M.A.); and Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Scuola di Scienze del Farmaco, Università degli studi di Milano, Milan, Italy (D.S.). Regional Blood Acidification Enhances Extracorporeal Carbon Dioxide Removal A 48-hour Animal Study Alberto Zanella, M.D., Paolo Mangili, M.D., Sara Redaelli, M.D., Vittorio Scaravilli, M.D., Marco Giani, M.D., Daniela Ferlicca, M.D., Diletta Scaccabarozzi, Federica Pirrone, D.V.M., Ph.D., Mariangela Albertini, D.V.M., Ph.D., Nicolò Patroniti, M.D., Antonio Pesenti, M.D. CRITICAL CARE MEDICINE Downloaded from http://pubs.asahq.org/anesthesiology/article-pdf/120/2/416/484809/20140200_0-00027.pdf by guest on 01 July 2022