| Objective:Nutritional support therapy, circulatory support and respiratory support have been called three support means in critically ill patients. Malnutrition and overfeeding were the common complication in critically ill patients who were accepted nutritional support therapy. Long time of malnutrition and overfeeding would lead to many complications, such as hyperlipidemia, hyperglycemia, hypercholesterolemia and so on. Inadequate feeding could lead to hypoproteinemia. Even if short-term incorret nutritional support would also cause adverse impact on the patient. Therefore, it is necessary to accurately assess the nutritional needs of the patient. Indirect calorimetry(IC) is considered to be the gold standard for assessment of energy expenditure(EE).According to the precise evaluation that could guide nutritional support therapy and improve the prognosis. All energy equations were foreign data and obtained by the noncritical patients. There were big difference between energy needs and the calculated equation values due to the diversity of race and physiological state. This study through the comparison with indirect calorimetry, select or derivate the energy prediction equation which close to indirect calorimetry and fit the patient.Methods: This study randomly selected the severe patients who was received mechanical ventilation and nutritional support in Hebei General Hospital intensive care unit from 2014 to 2015.The dates that we need contained: name, sex, age, height, weight, clinical diagnosis. Indirect calorimetry was performed using Engstrom Carestation ventilator(Datex-Ohmeda,Inc GE,USA). The device had a compact gas module which monitored breathing gas that transfused to patients and exhaled by the module and computed the energy consumption and respiratory quotient of patients. Measured 24-hour energy expenditure(EE) by indirect calorimetry in early experiment. Analyzed the experimental datas and computed short-term energy consumption about 3 hours in later experiment. At the same time, to assess the energy on all patients using American College of Chest Physicians(ACCP) equation, Harris-Benedict(H-B) equation, Ireton-Jones 1992 equation, Ireton-Jones 1997 equation, Penn State 1998 equation, Penn State 2003 equation, Swinamer 1990 equation. We used one-way ANOVA to test whether there was a difference in EE during the morning, afternoon, evening and night. Using the 24-hour data, we also calculated the maximal error if measurement time had been shorter(30, 60, 90, 120, 240 and 360 minutes). The nonlinear regression was used to curve-fit the data to a equation. Evaluated the EE of severe patients in different periods and reflected the shortest time about energy consumption monitoring. Using the correlation analysis to compare equation dates with measure dates and predicting the bias and accuracy of the equation by the confidence interval.to select the best equation which could evaluate the EE of critical patients.Results: Total of 89 patients(male 58 cases and female 31 cases) were enrolled in the study, of which 24 patients with respiratory failure, non-pulmonary, 28 patients with respiratory failure induced by pulmonary infection, 27 patients having suffered surgery, 2 patients after cardiopulmonary resuscitation, 6 patients with septic shock. The dates of age, height, weight, and APACHE II score not consistent with normality. Characteristics of the dates was showed as follow: the median of age was 79(rang30-98), the median of height was 168cm(range 150-179cm), the median of weight was 67kg(range 40-100kg), the median of APACHE II score was 12(range 3-36). At the beginning of the experiments we had collected 24 patients who meet the experimental conditions and were measured EE during 24 hours. Through analysis of variance, no statistically significant difference(P=0.944) in mean EE between night hours(0–6 hours), morning(6-12hours), afternoon(12-18hours) and evening(18-24hours). Instead of 24-hour date, we could account the average maximum deviations of 30-minute, 60-minute, 90-minute, 120-minute, 180-minute, 240-minute, 360 minute. According to the mean maximum of 24 patients, we curve-fit an equation as follow: Y=4102 × T-0.651(R2=0.996). A 181-minute could instead of a 24-hour measurement and the mean EE value within a 10% deviation would be acceptable. Indirect calorimetry result showed that the 24 energy expenditure in critical illness patients was 1369 kcal/day, 20.43kcal/kg/day. The 95% confidence interval of difference between predicted and measured EE as follow: Ireton-Jones 1997 equation(-24 ~ 57kcal) and Penn State 2003 equation(-74 ~ 79kcal) that the confidence interval included zero was considered unbiased; ACCP equation(84 ~ 204 kcal), Ireton-Jones 1992 equation(215 ~ 298 kcal), Penn State 1998 equation(43 ~ 139 kcal) and Swinamer 1990 equation(102 ~ 202 kcal) had tended to overestimation; H-B equation(-174 ~-128 kcal) was too low to assessment. All of the 95% confidence interval of absolute difference between predicted and measured EE > 10% of the measured EE. We considered that the equation had poor accuracy. But Ireton-Jones 1997 equation(absolute difference 11%) which was more close to the measured value. All equations were linearly associated with measured values, the Ireton-Jones 1997 equation had the highest correlation(r=0.620, P<0.001). Without considering the gender, age and body weight of patients, Ireton-Jones 1997 equation could be chosen to evaluate EE of patients in ICU. According to gender, age and whether obesity we can classify the patients(male/female 58/31, old/young 68/21, obese/non-obese 15/74). To analysis the bias, accuracy and relevance of patient’s EE in different groups that calculated by those equation in sequence. Ireton-Jones 1997 equation had a less accuracy in evaluating young patients compared with Penn State 2003 equation except that it was unbiased and had a good correlation. Ireton-Jones 1997 equation had a less accuracy for male, non-obese and young patients, however, the equation was suited to evaluate the patients who is the female and obese patients.Conclusions: When IC was used in mechanical ventilation patients, monitoring is not limited to a specific period of time. Only 3-hours measurement could reflect 24-hour energy expenditure. Indirect calorimetry result showed that the 24 energy expenditure in critical illness patients was 1369 kcal/day, 20.43kcal/kg/day. If we did not consider the gender, age and body weight, the evaluation of energy in critically ill patients preferentially chosen Ireton-Jones 1997 equation. There are some deviations when the energy expenditure computed by various predicted formula for critically ill patients, that would lead to nutritional deficiencies or over feeding. Indirect calorimetry can guide to supply individual energy in critically ill patients. |
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