An easy way to estimate energy expenditure from hemodynamic data in septic patients

Abstract

PURPOSE: The purpose of this study is to compare the resting energy expenditure (REE) obtained by indirect calorimetry (IC) to the REE calculated by predictive equations (Brandi and Liggett) using the oxygen consumption (VO2) obtained by Fick's method in septic patients. METHODS: Prospective study in septic patients admitted in an intensive care unit of a university hospital. Fifteen adult patients (11 men and four women) were studied. VO2 measurements were made using a portable metabolic cart connected to a respirator and a pulmonary artery catheter. RESULTS: The APACHE II at admission was 22.6±7.2 with a mortality risk of 46.1±27.7%. The mean REE obtained by IC and by the Brandi and Liggett equations were 1699±271, 1815±355 and 1361±277 kcal.day-1 respectively. There were no statistically significant differences between the two methods, with the two means showing a difference of 8.7%. REE values were close for IC x BRANDI (r=0.80), but the IC x LIGGETT correlation was only 0.58. CONCLUSIONS: The results suggest that REE can be easily calculated by obtaining VO2 with the Swan-Ganz catheter and using the Brandi equation even for septic patients under mechanical ventilation.

Methodological Aspects of Indirect Calorimetry in Patients with Sepsis—Possibilities and Limitations

“…The purpose of some studies that assessed EE was to evaluate energy metabolism in patients with sepsis (and possibly its relationship with disease severity and prognosis), compare the results obtained by various methods or develop new predictive equations. Nine such studies were identified [ 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. In other studies, EE was measured to assess its change under the influence of the interventions tested–hyperinsulinaemic clamp [ 61 , 62 , 63 ], liberation from mechanical ventilation [ 64 ], continuous renal replacement therapy [ 65 ], early exercise [ 66 ], or cardiac selective beta adrenergic [ 67 ].…”

“… Comparison of mean respiratory quotient (RQ) measured by indirect calorimetry in patients with sepsis or septic shock in selected studies. [ 52 , 53 , 54 , 55 , 56 , 57 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 67 ] Some studies have reported more than one RQ value. Time and conditions for obtaining measurements in individual tests may be different.…”

Nutrition therapy in critical illness: a review of the literature for clinicians

“…Due to the persistent inaccuracies associated with the use of predictive equations, other methods (many of which have existed for some time) have been recently recommended in the 2019 ESPEN critical care guideline in the absence of indirect calorimetry [2]. Resting energy expenditure (REE) can be estimated via VCO 2 (carbon dioxide production) from the ventilator and the rewritten Weir formula (REE = VCO 2 × 8.19) or using VO 2 (oxygen consumption) from a pulmonary artery catheter via the Fick method [19][20][21][22]. A recent study in 84 critically ill patients reported a higher level of agreement between energy requirements estimated by the VCO 2 method and measured REE compared to other predictive equations [20].…”

Indirect calorimetry: The 6 main issues

“…The Fick method allows to calculate the oxygen extraction across the pulmonary system and to extrapolate the EE. It requires the insertion of a catheter in the pulmonary artery and its invasiveness and relative imprecision limits its use (9).…”