Secondary Logo

Journal Logo

Institutional members access full text with Ovid®

Understanding the carbon dioxide gaps

Scheeren, Thomas W.L.a; Wicke, Jannis N.a; Teboul, Jean-Louisb,c

Current Opinion in Critical Care: June 2018 - Volume 24 - Issue 3 - p 181–189
doi: 10.1097/MCC.0000000000000493

Purpose of review The current review attempts to demonstrate the value of several forms of carbon dioxide (CO2) gaps in resuscitation of the critically ill patient as monitor for the adequacy of the circulation, as target for fluid resuscitation and also as predictor for outcome.

Recent findings Fluid resuscitation is one of the key treatments in many intensive care patients. It remains a challenge in daily practice as both a shortage and an overload in intravascular volume are potentially harmful. Many different approaches have been developed for use as target of fluid resuscitation. CO2 gaps can be used as surrogate for the adequacy of cardiac output (CO) and as marker for tissue perfusion and are therefore a potential target for resuscitation. CO2 gaps are easily measured via point-of-care analysers. We shed light on its potential use as nowadays it is not widely used in clinical practice despite its potential. Many studies were conducted on partial CO2 pressure differences or CO2 content (cCO2) differences either alone, or in combination with other markers for outcome or resuscitation adequacy. Furthermore, some studies deal with CO2 gap to O2 gap ratios as target for goal-directed fluid therapy or as marker for outcome.

Summary CO2 gap is a sensitive marker of tissue hypoperfusion, with added value over traditional markers of tissue hypoxia in situations in which an oxygen diffusion barrier exists such as in tissue oedema and impaired microcirculation. Venous-to-arterial cCO2 or partial pressure gaps can be used to evaluate whether attempts to increase CO should be made. Considering the potential of the several forms of CO2 measurements and its ease of use via point-of-care analysers, it is recommendable to implement CO2 gaps in standard clinical practice.

aDepartment of Anaesthesiology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands

bHôpitaux universitaires Paris-Sud, Hôpital de Bicêtre, Service de réanimation Médicale

cINSERM UMR S_999, Univ Paris-Sud, Paris, France

Correspondence to Thomas W.L. Scheeren, Department of Anaesthesiology, University Medical Centre Groningen, University of Groningen, Hanzeplein 1, PO Box 30 001, 9700 RB Groningen, The Netherlands. Tel: +31 50 361 6161; fax: +31 50 361 3763; e-mail:

Copyright © 2018 YEAR Wolters Kluwer Health, Inc. All rights reserved.