Alessandra Fabiane Lago

Harris-Benedict Equation and Resting Energy Expenditure Estimates in Critically Ill Ventilator Patients

BACKGROUND In routine practice, assessment of the nutritional status of critically ill patients still relies on traditional methods such as anthropometric measurements, biochemical markers, and predictive equations. OBJECTIVE To compare resting energy expenditure measured by indirect calorimetry (REEIC) with REE calculated by using the Harris-Benedict equation with 3 different sources of body weight (from bed scale, REEHB1; ideal body weight, REEHB2; and predicted body weight, REEHB3). METHODS This study included 205 critically ill patients (115 men, 90 women) evaluated within the first 48 hours of admission and undergoing mechanical ventilation. REE was measured by indirect calorimetry for 30 minutes and calculated by using the Harris-Benedict equation with the 3 sources of body weight. Data were compared by the Bland-Altman method. RESULTS The values based on ideal and predicted body weight (REEHB2 and REEHB3) did not agree with REEIC. Bland-Altman analysis showed that the limits of agreement varied from +796.1 kcal/d to -559.6 kcal/d for REEHB2 and from +809.2 kcal/d to -564.7 kcal/d for REEHB3. REEIC and REEHB1 (body weight determined by bed scale) agreed the best; the bias was -18.8 kcal/d. However, REEHB1 still overestimated REEIC by +555.3 kcal/d and underestimated it by -593.0 kcal/d. CONCLUSION For measuring REE in critically ill patients undergoing mechanical ventilation, calculation via the Harris-Benedict equation, regardless of the source of body weight, cannot be substituted for indirect calorimetry.

Energy expenditure in critically ill surgical patients. Comparative analysis of predictive equation and indirect calorimetry.

PURPOSE The aim of this investigation was to compare the resting energy expenditure (REE) calculated by the Harris-Benedict equation (REE HB) with the REE measured by indirect calorimetry (REE IC) in critically ill surgical patients under mechanical ventilation. METHODS Thirty patients were included in this work. REE was calculated by the Harris-Benedict equation (REE HB) using real body weight, and it was also measured by indirect calorimetry (REE IC), which was performed for 30 minutes. RESULTS REE HB had significant (p < 0.0005) but low correlation (Spearman r = 0.57) with REE IC, with a mean bias of 12 kcal.d-1 and limits of agreement ranging from - 599.7 to 623.7 kcal.d-1 as detected by the Bland-Altman analysis. CONCLUSION These findings suggest that REE IC seems to be more appropriate than REE HB for accurate measurement of REE in critically ill surgical patients under mechanical ventilation.

Are the Dysnatremias a Permanent Threat to the Critically Ill Patients

Backgroud The dysnatremias (hyponatremia and hypernatremia) are relatively common findings on admission of intensive care unit (ICU) patients and may represent a major risk. The aim of the study was to assess the ability of serum sodium levels and the Acute Physiology and Chronic Health Evaluation II (APACHE II) to predict mortality of surgical critically ill patients. Methods One hundred and ninety-five surgical patients (62% males and 38% females; mean age of 51.8 ± 17.3 years) admitted to the ICU in the postoperative phase were retrospectively studied. The patients were divided into survivors (n = 152) and non-survivors (n = 43). APACHE II, and serum sodium levels at admission, 48 h and discharge were analyzed by generation of receiver operating characteristic (ROC) curves. Results The mean APACHE II was 16.3 ± 8.3 (13.6 ± 6.1 for survivors and 25.5 ± 8.5 for non-survivors). The area under the ROC curve for APACHE II was 0.841 (0.782 - 0.889) and 0.721 (0.653 - 0.783), 0.754 (0.653 - 0.783) and 0.720 (0.687 - 0.812) for serum sodium level at admission, 48 h and discharge, respectively. Conclusion Even though APACHE II scoring system was the most effective index to predict mortality in the surgical critically ill patients, the serum sodium levels on admission may also be used as an independent predictor of outcome.

The apache ii and serum sodium levels as predictors of mortality in the surgical critically ill patients

The body sodium imbalance (dysnatremias) may be associated with increased mortality of critically ill patients. Evidence suggests that changes in the serum sodium level on admission to the intensive care unit (ICU), may lead to a poor outcome.

Comparison of Energy Expenditure and Oxygen Consumption of Spontaneous Breathing Trial Conducted With and Without Automatic Tube Compensation

Background Weaning from mechanical ventilation is defined as the process of release of ventilatory support and how the evaluation of this phase is conducted in the spontaneous breathing trial (SBT). One of the most used modes of SBT is the continuous positive airway pressure (CPAP), which applies a continuous positive pressure in both inspiration and expiration. However, together with the mechanical ventilation modes, the automatic tube compensation (ATC) can be used, which compensates the resistance imposed by the endotracheal tube. The objective of this study was to compare oxygen consumption (VO2) and energy expenditure (EE) during SBT conducted with and without ATC. Methods The study was prospective, randomized and crossover. Forty mechanically ventilated patients were admitted to an intensive care unit of a university tertiary hospital. The participants were randomly allocated in group 1, in which SBT was initiated with CPAP and ATC, followed by CPAP without ATC or in group 2, in which SBT was initiated with CPAP without ATC, followed by CPAP with ATC. Indirect calorimetry helped to measure VO2 and EE during SBT. Results The differences between VO2 and EE obtained during SBT with ATC and without ATC were -1.6 mL/kg/min (95% CI: -4.36 - 1.07) and 5.4 kcal/day (95% CI: -21.67 - 10.79), respectively. Conclusions We concluded that VO2 and EE obtained during SBT with and without ATC were not different.

Spontaneous breathing test conducted with and without automatic tube compensation does not differ from a metabolic standpoint

Weaning from mechanical ventilation is defined as the process of release of ventilatory support and how the evaluation of this phase is conducted in the Spontaneous Breathing Test (SBT). One of the most used modes of SBT is the Continuous Positive Airway Pressure (CPAP). However, together with the mechanical ventilation modes it can be used the Automatic Tube Compensation (ATC), which compensates the resistance imposed by the endotracheal tube.