Oxygen Consumption and Carbon Dioxide Production: Physiological Basis and Practical Application in Intensive Care

  • J. Takala
Conference paper


The metabolic production of carbon dioxide and consumption of oxygen reflect fundamental functions of the tissues. In the intensive care setting, carbon dioxide production (VCO2) and oxygen consumption (VO2) can be monitored from the respiratory gases [1-3] . When the body pool of CO2 and O2 are in a steady state, the VCO2 and VO2 measured from the respiratory gases represent the metabolic processes. VCO2 and VO2 are often considered merely as metabolic variables, and their monitoring by gas exchange measurements was originally introduced to intensive care as “metabolic monitoring”. The potential applications of gas exchange monitoring in intensive care are much broader. VCO2-monitoring can be used to monitor alveolar ventilation [4], the efficiency of CO2-removal (dead space to tidal volume ratio) and changes in ventilatory demand and their etiology [5] . VO2-monitoring can provide information on the adequacy of circulation or oxygen transport, especially when combined with mixed venous oximetry [6], and it can be used to evaluate the causes of arterial hypoxemia. In addition, gas exchange monitoring is useful in estimating the nutritional requirements and response to nutrition support in patients requiring prolonged intensive care [7]. Of all the potential applications of gas exchange monitoring, ventilation and oxygen transport related problems are probably the most frequent circumstances, where gas exchange monitoring can provide clinically relevant information.


Respiratory Quotient Carbon Dioxide Production Alveolar Ventilation Intensive Care Setting Oxygen Debt 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Takala J, Keinänen O, Väisänen P et al (1989) Measurement of gas exchange in intensive care: Laboratory and clinical validation of a new device. Crit Care Med 16:465–469CrossRefGoogle Scholar
  2. 2.
    Phang PT, Rich T, Ronco J (1990) A validation and comparison study of two metabolic monitors. JPEN 14:259–261CrossRefGoogle Scholar
  3. 3.
    Weissman C, Sardar A, Kemper M (1990) In vitro evaluation of a compact metabolic measurement instrument. JPEN 14:216–221CrossRefGoogle Scholar
  4. 4.
    Kiiski R, Takala J, Eissa NT (1991) Measurement of alveolar ventilation and changes in deadspace by indirect calorimetry during mechanical ventilation: A laboratory and clinical validation. Crit Care Med 19:1303–1309PubMedCrossRefGoogle Scholar
  5. 5.
    Kiiski R, Takala J(1994) Hypermetabolism and efficiency of CO2 removal in acute respiratory failure. Chest 105:1198–1203PubMedCrossRefGoogle Scholar
  6. 6.
    Keinänen O, Takala J, Kari A (1992) Continuous measurement of cardiac output by the Fick principle: Clinical validation in intensive care. Crit Care Med 20:360–365PubMedCrossRefGoogle Scholar
  7. 7.
    Takala J (1993) Nutrition and metabolism in acute respiratory failure. In: Wilmore DW, Carpentier YA (eds) Update in Intensive Care and Emergency Medicine 17. Metabolic Support of the Critically Ill Patient. Springer, Berlin Heidelberg New York, pp 390–406CrossRefGoogle Scholar
  8. 8.
    (1996) Complete proceedings of the 3rd European Consensus Conference in Intensive Care, Paris, December 7–8 1995. Rèan Urg 5:161–313Google Scholar
  9. 9.
    Weissman C, Kemper M, Damask MC et al (1986) The energy expenditure of the mechanically ventilated critically ill patient. An analysis. Chest 89:254–259CrossRefGoogle Scholar
  10. 10.
    Takala J, Ruokonen E (1993) Assessment of systemic and regional oxygen delivery and consumption. In: Vincent JL (ed) Yearbook of Intensive Care and Emergency Medicine. Springer, Berlin Heidelberg New York, pp 413–421Google Scholar
  11. 11.
    Ultman JS, Bursztein S (1981) Analysis of error in the determination of respiratory gas exchange at varying FiO2. J Appl Physiol 50:210–216PubMedGoogle Scholar
  12. 12.
    Nunn JF(1996) Pulmonary oxygen consumption. Intens Care Med 22:275–276CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Italia 1997

Authors and Affiliations

  • J. Takala

There are no affiliations available

Personalised recommendations