Question 7.4

The following haemodynamic and metabolic data were obtained from a patient admitted to the ICU with sepsis.

Pulmonary artery catheter data:

  • CI 4.2 L/min/m2
  • DO2 900 ml/min
  • VO2 190 ml/min

Indirect calorimetry data:

  • VO2 220 ml/min
  • VCO2 290 ml/min

a) Why is the VO2 different between the two methods? (Assume no measurement errors.)

b) What changes in patient management will you consider based on the indirect calorimetry data?

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College Answer

a) Indirect calorimetry also measures lung oxygen consumption.

b) A high RQ suggests excess carbohydrate load. Reduce caloric intake and consider changing to a higher fat intake.


This question is identical to Question 25.4 from the second paper of 2010.

Indirect calorimetry and the reverse Fick method are discussed in detail elsewhere.