Flávio Marson

Correlação entre o consumo de oxigênio obtido pelo método de Fick e pela calorimetria indireta no paciente grave

OBJECTIVE To compare the oxygen consumption index measured by using indirect calorimetry (VO2I Delta) with a portable metabolic cart and calculated according to Ficks principle (VO2 I Fick) in critically ill patients. METHODS Fourteen patients (10 men and 4 women, mean age 39.4 +/- 5.4 years) were analyzed, 5 of them trauma victims and 9 sepsis victims. The following mean scores were obtained for these patients: APACHE II = 21.3+/-1.8, ISS = 24.8+/-6, and sepsis score = 19.6+/-2.3. The mortality risk (odds ratio), calculated from APACHE II, was 41.9+/-7.1%. All patients underwent mechanical ventilation and invasive hemodynamic monitoring with a Swan-Ganz catheter. VO2 was obtained using the 2 methods (VO2I Delta and VO2I Fick) at 4 different times (T1-T4). RESULTS A good correlation was found between the 2 methods (r=0.77) for the mean of the 4 serial measurements. No statistically significant differences were observed between indirect calorimetry and Ficks equation at T1 (VO2I Delta = 138+/-28 and VO2I Fick = 59+/-38 mL.min-2.m-2, P=0.10) and T3 (VO2I Delta = 144+/-26 and VO2I Fick = 158+/-35 mL.min-2.m-2, P=0.14), but a significant difference was observed at T2 (VO2I Delta = 141+/-27 and VO2I Fick = 155+/-26 mL.min-2.m-2, P=0.03) and T4 (VO2I Delta = 145+/-24 and VO2I Fick = 162+/-26 mL.min-2.m-2, P=0.01). CONCLUSION We may state that indirect calorimetry can be used for oxygen consumption analysis in critically ill patients and is as efficient as Ficks reverse equation, with the benefit of being a noninvasive and risk-free procedure.

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

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 Ficks 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.