Savard et al identified factors which may affect the accuracy of calorimetric measurements of resting energy expenditures in a patient receiving mechanical ventilation. Extra care must be taken when one or more of these factors are present. The authors are from multiple hospitals in Paris and Quebec.


Factors which need to be taken into account when measuring resting energy expenditure in a mechanically ventilated patient:

(1) hemodynamic instability (with need for fluid resuscitation and inotropic support)

(2) respiratory instability (with hypoxemia or change in respiratory mechanics)

(3) variation in the carbon dioxide pool (from infusion of bicarbonate, urinary or GI loss, dialysis, etc)

(4) thermogenesis from administered carbohydrates and other nutrients

(5) air leaks in the ventilatory system

(6) accumulation of ketones and other intermediate metabolites

(7) very high FIO2 (> 80%)


The total energy expenditure needs to take into account factors resulting in increased energy expenditures (febrile illness or inflammation, surgery, malignancy, trauma, etc) above the resting energy expenditure.


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