This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Hoher, J. A. Articles by da S. Moreira, J. Search for Related Content PubMed PubMed Citation Articles by Hoher, J. A. Articles by da S. Moreira, J. Pubmed/NCBI databases Medline Plus Health Information Diets Social Bookmarking                   What's this?

A Comparison Between Ventilation Modes: How Does Activity Level Affect Energy Expenditure Estimates?

From the ¹ Central Intensive Care Unit, Complexo Hospitalar Santa Casa, Porto Alegre, Brazil;² Pavilhão Pereira Filho, Complexo Hospitalar Santa Casa, and Centro Universitário FEEVALE and Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; ³ School of Medicine, Fundação Federal Faculdade de Ciências Médicas de Porto Alegre, Porto Alegre, Brazil; and⁴ Pavilhão Pereira Filho, Complexo Hospitalar Santa Casa, and Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.

Address correspondence to: Jorge A. Hoher, MD, PhD, Rua Anita Garibaldi, 1161, apto 502, Bairro Mont'Serrat, CEP 90.450-001, Porto Alegre, RS, Brazil; e-mail: jah{at}via-rs.net.

Background: An appropriate diet is essential to avoid complications of overfeeding or underfeeding in mechanically ventilated intensive care unit (ICU) patients. The paucity of consistent comparative data on energy expenditure for each ventilation mode complicates diet prescription. This study evaluates caloric requirements by comparing estimated and measured energy expenditure values for 2 ventilation modes. Methods: The energy expenditure of 100 ICU patients on assisted or controlled mechanical ventilation was measured by indirect calorimetry for 20 minutes. Values were calculated for a 24-hour period and compared with Harris-Benedict estimates multiplied by an injury factor and either multiplied or not by a 10% activity factor. Results: The mean Harris-Benedict estimate was 1858.87 ± 488.67 kcal/24 h when multiplied by an injury factor and a 10% activity factor. The mean energy expenditure values measured by indirect calorimetry were 1712.76 ± 491.95 kcal/24 h for controlled and 1867.33 ± 542.67 kcal/24 h for assisted ventilation. The mean total energy expenditure for assisted ventilation was 10.71% greater than the mean for controlled ventilation (P < .001). For controlled ventilation, Harris-Benedict results overestimated indirect calorimetry values by 141.10 ± 10 kcal/24 h (8.2%, P = .012) when multiplied by injury and activity factors, and underestimated values by 44.28 ± 28 kcal/24 h (2.6%, P = .399) when the equation was calculated without the activity factor. For assisted ventilation, Harris-Benedict results underestimated indirect calorimetry values by 198.84 ± 84 kcal/24 h (10.7%, P = .001) when not multiplied by the activity factor and by 13.46 kcal/24 h (0.75%) when the activity factor was used, but differences were not statistically significant (P = .829). Conclusions: Results suggest that a 10% activity factor should be adopted only for assisted ventilation because multiplication by an activity factor may lead to overfeeding of patients on controlled ventilation.

Key Words: energy expenditure • indirect calorimetry • mechanical ventilation • nutrition

Inappropriate nutrition, described as underfeeding or overfeeding, may cause important complications that affect the progression of the disease,^1,2 especially in critically ill patients receiving mechanical ventilation.^3-6 Poorer outcomes, longer mechanical ventilation, higher infection risks, and increased mortality rates have all been associated with underfeeding.⁷

Similarly, overfeeding of critically ill patients should be avoided because of hypermetabolism and increased catecholamines, which increase cardiorespiratory demand, time on mechanical ventilation, and energy expenditure.⁵ In addition, overfeeding may cause hyperglycemia, osmotic diuresis, hyperosmolar states, fatty infiltration in the liver, excessive carbon dioxide production, and the worsening of respiratory function.^8-10

Mechanically ventilated patients make a considerable respiratory muscle effort that is not always alleviated by intermittent positive pressure ventilation. According to Ward et al,¹¹ no work of breathing is observed in patients under controlled mechanical ventilation who are receiving drugs for sedation and muscle paralysis. In this situation, the work of breathing is carried out by the ventilator which initiates the ventilation cycle, and patients are spared the inspiratory efforts. Conversely, in assisted ventilation modes, the patient has to make a considerable inspiratory effort before a ventilation cycle initiates, and there is no airflow up to the moment when the effective sensitivity threshold is reached by the ventilator.^12-14 Therefore, the choice of ventilation mode may determine differences in energy expenditure.

The method of choice to determine resting energy expenditure is indirect calorimetry (IC) as measured by total volume of expired gas. However, when IC is not available, prediction equations, such as the well-known Harris-Benedict (H-B) equation, are routinely used.¹⁵ Considering the range of factors affecting energy expenditure, the accurate establishment of actual calorie requirements becomes crucial to adjust calorie intake for patients on any mechanical ventilation mode.

As far as we know, no studies have measured the difference in total energy expenditure (TEE) for patients receiving assisted and controlled mechanical ventilation. This study calculated the energy expenditure of patients on assisted or controlled mechanical ventilation using the H-B equation multiplied and not multiplied by an activity factor, and compared the results with the values measured using IC.

	Methods

Top Methods Results Discussion

 
This study was conducted in the Intensive Care Unit (ICU) of Complexo Hospitalar Santa Casa, Porto Alegre, Brazil, and was approved by the Committee for Ethics in Research. Informed consent was signed by a relative of each patient eligible to participate in the study. The study population initially comprised 122 ICU inpatients (65 men) aged 17-91 years. All patients were mechanically ventilated with Servo 900-C respirators (Siemens, Sweden). The patients were included in the study if they could receive either ventilation mode (assisted or controlled) without any negative impact on respiratory function and if hemoglobin saturation could be maintained at a level > 90%. At admission, patients underwent subjective global assessment,¹⁶ and usual body weight was obtained from the patient or a family member because a bed scale was not available in the ICU. Recumbent height was measured with the patient lying supine on a fully horizontal bed. The points at the crown of the head and heels were marked on the bed, and the distance between these 2 points was measured with a flexible tape.¹⁷ Reported usual weight and measured recumbent height were used to calculate body mass index (BMI = weight/height²). Because most patients were admitted a few days before they were included in the study, when IC measurements were made, weight was reviewed by 2 observers (the assistant nurse and investigator) to assess possible weight loss or gain during the ICU stay. As weight did not seem to have changed substantially in any patient, usual weight reported at admission was used for calculations.

Exclusion criteria were tracheostomy or any evidence of air leakage. Also excluded from the study were patients with an inspiratory oxygen fraction (FiO₂) >60% and hemodynamic instability or renal failure with acidosis and serum HCO₃–lower than 15 mmol/L and those who had already undergone hemodialysis.¹⁸

To calculate calorie requirements, TEE was estimated using basal energy expenditure (BEE) according to the H-B equation^15,19 considering usual weight reported at admission. The TEE is the BEE calculated using the H-B equation adjusted for the levels of activity and stress for each patient. To obtain TEE, the BEE was multiplied by factors that adjust for activity and for injury or disease. The table of commonly used activity and injury factors was published by Van Way.¹⁹

The activity factor was chosen because it adjusts for the difference in energy expenditure between patients on bed rest only (1.15) and patients on bed rest and mechanical ventilation (1.10). The 1.10 activity factor was used for all patients because they were all on mechanical ventilation.

The stress or injury factor is the most imprecise element of the calculation. When it was unclear which factor should be used, the lowest factor was chosen.¹⁹ Different factors were used for different patients according to the degree of hypermetabolism indicated by the patient's clinical condition (see Table A1 in the appendix). The TEE of 26 patients who were receiving no nutrition was estimated in the same way.

The IC was calculated according to exhaled O₂ and CO₂ measured by a pneumotachograph placed between the endotracheal tube and the exhalation branch of the respirator tube. Data collected were used in the Weir equation (TEE = 3.9[VO₂] + 1.1[VCO₂]1.44)²⁰ to calculate the TEE. The barometric pressure of gases was calibrated before each measurement (monitors TEEM-100, Inbrasport Inc, Ann Arbor, MI, and Datex-Ohmeda S/5–Compact Airway Module, model MCAIOVX, Datex Instrumentarium, Helsinki, Finland). Measurement procedures have been described in detail in the literature,^21-23 but protocols for the measurement of resting energy expenditure of mechanically ventilated patients are not standardized. These measures are usually collected for 20-30 minutes.^18,20-22,24

Before IC measurements, patients had not undergone any recent procedures that might affect energy expenditure. Tracheal aspiration was carried out 5 minutes before the test, and no ventilation settings were changed for at least 1 hour before the test. Measurements were made if the patient status remained unchanged after 1 hour in the same ventilation mode.¹⁸ The first measurement was made when the patient had been on controlled ventilation for 20 minutes. During the measurement, gases were analyzed every 20 seconds, and the results (divided by 20 and multiplied by 1440) were used to calculate calories per 24 hours. After that, the ventilation mode was changed to assisted ventilation, and all measurements were repeated.

Clinical stability signs were checked to ensure accuracy.^18,21,22-25 A stable state was achieved before actual measurements took place and was defined by the following criteria:

• gas collection system was fully sealed, especially the endotracheal tube, calorimeter tube, and respirator;
  
• patient was calm and stable and sedation was allowed, as long as assisted ventilation was possible;
  
• tracheal aspiration was carried out 5 minutes before measurement;
  
• no thermogenic effects, such as fever, were detected;
  
• FiO₂ was <0.6^21,25-28;
  
• electric power and gas supply were stable, ICU environment met standard conditions, and temperature was between 21°C and 23°C;
  
• equipment was appropriately calibrated, as defined by manufacturer;
  
• measurements were made for 20 minutes under constant monitoring by the same observer; and
  
• no plateau pressures >40 cm H₂O were indicated by respirator (higher pressures may affect the results of the gas analyzer²²) and positive end expiratory pressure (PEEP) was set at 5 cm H₂O for the 2 examinations in all cases.
  

Twenty-two patients were excluded from the study because they did not tolerate the change of ventilation mode, which was indicated by desaturation values <90%, tachycardia, fever, sweating, or sensory alterations during data collection.

Patient data comprised hospital admission number, gender, age, reason for ICU admission, PaO₂-FiO₂ ratio, hemoglobin saturation, sensory status, APACHE II²⁹ score, subjective global assessment data, usual body weight, height, BMI,^16,30,31 TEE estimated by the H-B equation, use of vasoactive agent, use of special diet, type of nutrition (enteral, parenteral, or no nutrition), days on mechanical ventilation, VO₂ and VCO₂ values, inspiratory-to-expiratory ratio, and calories spent between 1 and 20 minutes and plotted to 1440 minutes. Also, data on ventilatory mechanics were collected for respiratory rate, tidal volume, pressure variation, PEEP, hemoglobin saturation, FiO_2, peak pressure, plateau pressure, average pressure, calculated pressure, dynamic compliance, and airway resistance.^32,33

Patients were stratified according to whether they had infection or sepsis on admission or during hospital stay.

Data were analyzed using the Statistical Package for the Social Sciences (SPSS 10.0). The paired Student t test and factorial ANOVA were used to compare means. The significance level was P .05.

	Results

Top Methods Results Discussion

 
One hundred ICU patients (52 men; mean age, 62.7 ± 7.2 years) were included in the study. Data were analyzed according to gender, age group, presence of sepsis, subjective global assessment, obesity, type of nutrition (enteral, parenteral, or no nutrition), use of vasoactive drugs, changes in dynamic compliance, and variation of inspiratory-to-expiratory ratio. The study population characteristics are shown in Table 1.

Severity of illness was established by APACHE II, and the mean score was 21.1 ± 8.3. Time on mechanical ventilation ranged from 1 to 60 days, and the mean time was 5.0 ± 7.8 days. The subjective global assessment revealed that 81% of the patients were well nourished, 19% were moderately malnourished, and none were severely malnourished; BMI revealed that 19% were underweight, 74% were normal weight, no patients were overweight, and 7% were obese (BMI 30 kg/m²).

Sixty-nine patients received standardized enteral nutrition, 26 received no nutrition, and 5 received parenteral nutrition. Ten patients were taking vasoactive drugs to maintain hemodynamic stability during IC.

During the hospital stay or at admission, 35 patients were diagnosed with infection and 20 with sepsis. Although the presence of infection or sepsis was an exclusion criterion, the stratified analysis of these patients was included in the study to avoid potential bias by infection and sepsis.

The TEE values estimated with the H-B equation and measured by IC are shown in Table 2.

In the controlled ventilation test, the comparison between TEE means obtained by IC and by using the H-B equation multiplied by injury and activity factors revealed that the H-B equation overestimated the IC value by 141.03 kcal/24 h (8.2%; P = .012). When the activity factor was not used, TEE was underestimated by 44.28 kcal/24 h (2.6%; P = .399). In the assisted ventilation test, the TEE calculated using the H-B equation but no activity factor underestimated IC values by 198.84 kcal/24 h (10.71%; P = .001). When the activity factor was used, TEE underestimation was 13.46 kcal/24 h (0.75%; P = .829), as shown in Table 3.

Mean TEE values measured by IC were 1712.76 ± 491.95 kcal/24 h for controlled ventilation and 1867.33 ± 542.67 kcal/24 h for assisted ventilation. The mean TEE value was 10.71% (±23.88) greater for assisted ventilation than for controlled ventilation (P < .001; Figure 1).

View larger version (7K): [in this window] [in a new window]   Figure 1. Total energy expenditure measured by indirect calorimetry for assisted and controlled ventilation modes expressed as mean values and standard deviations.

View larger version (14K): [in this window] [in a new window]   Figure 2. Correlation between total energy expenditure (TEE) estimated by the Harris-Benedict equation and TEE measured by indirect calorimetry (IC) for controlled ventilation.

View larger version (13K): [in this window] [in a new window]   Figure 3. Correlation between total energy expenditure (TEE) estimated by the Harris-Benedict equation and TEE measured by indirect calorimetry (IC) for assisted ventilation.

The stratification of patients according to use of vasoactive drugs, infection, or sepsis did not reveal any significant differences in TEE values in controlled or assisted ventilation, as shown in Table 4.

ANOVA results did not reveal any statistical differences in TEE values between patients receiving no nutrition, parenteral nutrition, or enteral nutrition in both ventilation modes (P = .438).

To analyze the effect of age, patients were divided into 3 age groups: 17-40 years, 41-60 years, and 61-91 years. The ANOVA results did not show any statistical differences in TEE between age groups in both ventilation modes (P = .715).

However, a significant statistical difference in dynamic compliance was found between the 2 ventilation modes. For controlled ventilation, the mean was 29.17 ± 10.38 mL/cm H₂O, and for assisted ventilation, the mean was 33.89 ± 15.21 mL/cm H₂O. Dynamic compliance was higher for the assisted ventilation mode (P < .001).

	Discussion

Top Methods Results Discussion

 
This study used IC to assess energy expenditure for 2 ventilation modes, controlled and assisted ventilation, and compared results with values estimated with the H-B equation using individual stress factors with or without multiplication by an activity factor. Our results showed that, for assisted ventilation, the H-B equation, multiplied by a stress factor but not an activity factor, underestimated energy expenditure by 198.84 kcal/24 h, which was 10.71% lower than the results measured by IC. These results are in accordance with current knowledge about ventilation mechanics, which takes into account the effort made before the beginning of the assisted ventilation cycle. This is the moment when the patient, still with no airflow in the airways, expends energy by moving the respiratory muscles to reach the sensitivity threshold of the respirator. Conversely, this respiratory effort is not observed in controlled ventilation modes because the machine initiates the ventilation cycle according to the settings in the machine and the patient makes no efforts, which is the case of patients under sedation or curarization in particular.^11,34,35

The analysis of TEE values for controlled ventilation revealed that the H-B equation multiplied by the individual stress factor but not an activity factor underestimated IC by 2.6%. When the activity factor was included in the calculation, the equation overestimated IC by 8.2%. For assisted ventilation values calculated with and without the activity factor, TEE was underestimated by 0.75% and 10.71%, respectively.

IC results revealed that patients under assisted ventilation spent 10.71% (±23.88 kcal/24 h) more energy than patients under controlled ventilation, which suggests that the energy expenditure calculated with the 1.10 activity factor, that is, 10% above resting values, should be used only for assisted ventilation. This finding is clear evidence that energy expenditure for assisted ventilation patients is significantly greater.

The conclusions of previous studies about energy expenditure measured by IC or estimated using the H-B equation cannot be directly compared with our results. van Lanschot et al³⁶ carried out a study with 25 surgical ICU patients and reported that the poor correlation between basal energy requirements estimated using the H-B equation and IC energy measurements improved when injury factors for individual patients were used. Their study, however, evaluated only surgical patients and did not analyze the differences between the 2 ventilation modes.

Our study showed that the mean energy expenditure estimated by the H-B equation when both correction factors (activity and injury) were used was 1853 ± 488.67 kcal/24 h, whereas values measured using the IC were 1712.76 ± 491.95 kcal/24 h when patients were on controlled ventilation and 1867.33 ± 542.67 kcal/24 h when on assisted ventilation. A positive correlation was found between measured and estimated values for both controlled (r = 0.374; P < .001) and assisted (r = 0.281; P < .005) ventilation modes, which additionally reveals a somewhat more positive correlation for controlled ventilation.

One limitation of our study is the fact that estimates were calculated using subjectively evaluated data, such as weight, which may skew the values obtained for the comparison with IC values. Another limitation was the fact that an activity factor was not included in IC measurements, as suggested by some authors.^20,26,37,38 The decision not to include it was based on the fact that this study evaluated energy expenditure in different mechanical ventilation modes at the same time point and under the same clinical conditions, which reduced chances of an activity factor affecting measured values. However, Damask et al,²⁰ as well as Weissman et al^37,38 and Swinamer et al,²⁶ suggest that, as measurements are usually made during rest, an activity factor be added to calculate TEE. Therefore, for ICU patients, 5%-10% should be added to IC calculations to account for activity.

Swinamer et al²⁶ reported that H-B estimates do not accurately predict energy expenditure in critically ill patients, as the discrepancy between values was >15% for the 79 patients they studied. Faisy et al³⁹ compared the energy expenditure of 70 adults who were intubated and mechanically ventilated for >24 hours and found that the energy expenditure was 25% greater than the resting energy expenditure estimated by the equation when correction factors were used in the calculation. These 2 studies did not compare energy expenditures according to ventilation modes. Cheng et al,⁵ however, studied 46 patients divided into 3 groups according to the type of nutrition support (enteral nutrition, parenteral nutrition, or combined) and reported no significant differences between IC values and H-B estimates multiplied by an injury factor. Similar to our study, they showed that the type of nutrition did not significantly affect the comparison of IC and H-B equation values.

In a study of 28 patients with sepsis, Colleto⁴⁰ compared IC values with H-B estimates and concluded that the equation results calculated without correction factors, as suggested by Long et al,⁴¹ seemed to be more appropriate to assess energy expenditure in critically ill patients. When the equation was multiplied by correction factors, energy expenditure was overestimated by >50%. Different from our study, they evaluated only patients with sepsis. In our study, although patients did not have infection or sepsis when IC measurements were made, the comparison between patients with and without infection showed that this type of morbidity has no effect on TEE values.

The nutrition status assessment of all patients included in our study showed that most were well nourished and only 7% were obese. Singer and Singer,⁴² in a study that compared measured and estimated energy expenditure in 75 patients divided into 3 groups according to body weight (normal, overweight, and obese), reported that the measured values of obese and overweight patients were 30% greater than estimated values. The H-B equation underestimated energy expenditure of obese patients, and IC produced results that were more accurate. Nonino⁴³ studied class 3 obese women and concluded that the H-B equation did not reliably estimate TEE and that the equation results were consistent only when a low-calorie diet was adopted and subsequent weight loss was observed. In our study, nutrition status and obesity did not affect the correlation between energy expenditure measured by IC or estimated by the H-B equation, which is different from findings reported by Singer and Singer⁴² and Nonino,⁴³ who studied different patient samples.

The fact that some patients received enteral, parenteral, or no nutrition did not affect TEE values for any of the 2 ventilation modes. Also, age and use of vasoactive drugs had no effect on energy requirements. Ribeiro,⁴⁴ in a review published with the title "Nutritional Therapy in Sepsis," suggested that the H-B equation with no multiplication by injury factors should be used for critically ill patients to avoid overfeeding.

A significant increase in TEE of men in comparison with women was observed during controlled ventilation. On assisted ventilation, results for men showed a trend only toward greater TEE. These findings corroborate current knowledge that basal energy requirements are greater for men.

The comparison of TEE values measured by IC for 20 minutes of controlled and assisted ventilation revealed that patients on assisted ventilation spent 10.71% more energy than patients on controlled ventilation (P < .001).

In conclusion, our results suggest that, in addition to the injury factor, the activity factor (1.10) should be used only in the calculation for patients on assisted ventilation.

We are indebted to the Central ICU of Hospital Santa Casa, to all nurses of our hospital who provided priceless assistance for the development of the study, and to all the librarians who dedicated time and attention to our work.

Top Methods Results Discussion

 
Financial disclosure: This study was conducted without grants and relied entirely on the private resources of the authors, without conflict of interests.

Received for publication June 21, 2007. Accepted for publication November 20, 2007.

1. Askanazi J, Rosembaum SH, Hyman AI, Silverberg PA, Milic-Emily J, Kinney JM. Respiratory changes induced by the large glucose loads of total parenteral nutrition. JAMA.1980; 243:1444 -1447.[Abstract/Free Full Text]
2. Covelli HD, Black JW, Olesson MS, Beekman JF. Respiratory failure precipitated by high carbohydrate loads. Ann Intern Med.1981; 95:579 -581.[Abstract/Free Full Text]
3. Ireton-Jones CS, Borman KR, Turner WW. Nutrition considerations in the management of ventilator-dependent patients. Nutr Clin Pract. 1993;8:60 -64.[Abstract/Free Full Text]
4. Christman JW, McCain RW. A sensible approach to the nutritional support of mechanically ventilated critically ill patients. Intensive Care Med. 1993;19:129 -133.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
5. Cheng CH, Chen CH, Wong Y, Lee BS, Kan MN, Huang YC. Measured versus estimated energy expenditure in mechanically ventilated critically ill patients. Clin Nutr.2002; 21:165 -172.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
6. Benotti PN, Bistrian B. Metabolic and nutritional aspects of weaning from mechanical ventilated. Crit Care Med.1989; 17:181 .[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
7. Krishnan JA, Parce PB, Martinez A, Diette GB, Brower RC. Caloric intake in medical icu patients: consistency of care with guidelines and relationship to clinical outcomes. Chest.2003; 124:297 -305.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
8. Mullen JL. Indirect calorimetry in critical care. Proc Nutr Soc. 1991;50:239 -244.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
9. Hernandez Chávez A, Corona Jiménez F, Gutiérrez de La Rosa JL, Hernandez Jiménez A, Cumplido Hernandez G, López Guillén P. El gasto energético en reposo, medido contra estimado, em pacientes críticamente enfermos. Gac Méd Méx. 1994;131:283 -288.
10. Cunningham K, Aeberhardt LE, Wiggs BR, Phang PT. Appropriate interpretation of indirect calorimetry for determining energy expenditure of patients in intensive care units. Am J Surg.1994; 167:547 -549.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
11. Ward ME, Corbeil C, Gibbons W, Newman S, Macklem P. Optimization of respiratory muscle relaxation during mechanical ventilation.Anesthesiology . 1988;69:29 -35.[Web of Science][Medline] [Order article via Infotrieve]
12. Marini JJ. Mechanical ventilation: taking the work out of breathing? Respir Care.1986; 31:696 -702.
13. Cox D, Tinloi SF, Farrimond JG. Investigation of the spontaneous modes of breathing of different ventilators. Intensive Care Med. 1988;14:532 -537.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
14. Capps JS, Ritz R, Pierson DJ. An evaluation in four ventilators of characteristics that affect work of breathing. Respir Care.1987; 32:1017 -1024.
15. Harris JA, Benedict FG. A Biometric Study of Basal Metabolism in Man. Publication 279. Washington, DC: Carnegie Institute of Washington; 1919.
16. Detsky AS, McLaughlin JR, Baker JP, et al. What is subjective global assessment of nutritional status? JPEN J Parenter Enteral Nutr. 1987;11:8 -13.[Abstract]
17. Lohman TG, Rocha AF, Martorell R. Anthropometric Standardization Reference Manual. Abridged ed. Chicago, IL: Human Kinetics Books; 1991.
18. Petros S, Engelmann L. Validity of an abbreviated indirect calorimetry protocol for measurement of resting energy expenditure in mechanically ventilated and spontaneously breathing critically ill patients.Intensive Care Med .2001; 27:1164 -1168.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
19. Van Way CW III. Nutrition Secrets. Philadelphia, PA: Hanley & Belfus, Inc; 1999.
20. Damask MC, Schwarz Y, Weissmann C. Energy measurements and requirements of critically ill patients. Crit Care Clin.1987; 3:71 -96.[Web of Science][Medline] [Order article via Infotrieve]
21. Basile-Filho A, Martins M, Antoniazzi PC, Marchini JS. Indirect calorimetry in the critically ill patient. RBTI.2003; 15:29 -33.
22. Diener JRC. Calorimetria Indireta. Rev Assoc Med Bras. 1997;43:245 -253.[Medline] [Order article via Infotrieve]
23. Martins MA, Campos Filho WO, Viana JM, Nicolini EA, Campos AD, Basile-Filho A. Comparative analysis of cardiac output (CO) calculated by Fick's method and measured by indirect calorimetry in septic patients.RBTI . 2003;15:5 -14.
24. Burzstein S, Saphar P, Singer P, Elwyn DH. A mathematical analysis of indirect calorimetry measurements in cutely ill patients. Am J Clin Nutr. 1989;50:227 -230.[Abstract/Free Full Text]
25. Takala J, Merilánen P. Handbook of Gas Exchange and Indirect Calorimetry. Datex-Ohmeda. Doc. 876710. Kuopio, Finland: Datex-Ohmeda Division, Instrumentarium Corp; 1990.
26. Swinamer DL, Grace MG, Hamilton SM, Jones RL, Roberts P, King G. Predictive equation for assessing energy metabolism in mechanically ventilated critically ill patients. Crit Care Med.1990; 18:657 .[Web of Science][Medline] [Order article via Infotrieve]
27. Brandi LS, Bertolini R, Calafà M. Indirect calorimetry in critically ill patients: clinical applications and practical advice.Nutrition . 1997;13:349 -358.[Web of Science][Medline] [Order article via Infotrieve]
28. Basile-Filho A, Martins MA, Batiston MT, Vinha PP. Energy expenditure in septic patients: correlation between indirect calorimetry and predictive equations derivated from hemodynamic data. RBTI.2003; 15:101 -107.
29. Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: a severity of disease classification system. Crit Care Med.1985; 13:818 -829.[Web of Science][Medline] [Order article via Infotrieve]
30. Grant JP, Custer PB, Thurlow J. Current techniques of nutritional assessment. Symposium on Surgical Nutrition. Surg Clin North Am. 1981;61:437 -463.[Web of Science][Medline] [Order article via Infotrieve]
31. Baker JP, Detsky AS, Wessom DE, Wolman SL, Stewart S, Whitewell J. Nutritional assessment. N Engl J Med.1982; 306:969 -972.[Web of Science][Medline] [Order article via Infotrieve]
32. Vieira SRR, Plotnik R, Fialkow L. Monitorização da Mecânica Respiratória Durante a Ventilação Mecânica In: Carvalho CRR, ed. Ventilação Mecânica. Vol 1. Básico. São Paulo, Brazil: Editora Atheneu; 2000:215 -252.
33. Tobin MJ, van de Graeff WB. Monitoring of lung mechanics and the work of breathing. In: Tobin MJ, ed. Principles and Practice of Mechanical Ventilation. New York, NY: McGraw-Hill; 1994:967 -1003.
34. Amato MBP, Barbas CSV. Trabalho respiratório. In:Princípios da Ventilação Mecânica. Barcelona, Spain: Permanyer Publications; 1998:55 -74.
35. Annat G, Viale JP. Measuring the breathing workload in mechanically ventilated patients. Intensive Care Med.1990; 16:418 -421.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
36. van Lanschot JJB, Feenstra BWA, Vermeij CG, Bruining HA. Calculation versus measurement of total energy expenditure. Crit Care Med. 1986;14:981 -985.[Web of Science][Medline] [Order article via Infotrieve]
37. Weissman C, Kemper M, Hyman AI. Variation in the resting metabolic rate of mechanically ventilated critically ill patients. Anesth Analg. 1989;68:457 -461.[Abstract/Free Full Text]
38. Weissman C, Kemper M, Elwyn DH, Askanazi J, Hyman AI, Kinney JM. The energy expenditure of the mechanically ventilated critically ill patient.Chest . 1986;89:254 -259.[CrossRef][Web of Science][Medline] [Order article via Infotrieve]
39. Faisy C, Guerrot E, Diehl J-L, Labrousse J, Fagon JY. Assessment of resting energy expenditure in mechanically ventilated patients. Am J Clin Nutr. 2003;78:241 -249.[Abstract/Free Full Text]
40. Colleto FA. Avaliação do gasto energético obtido pela calorimetria indireta e pela equação de Harris-Benedict no paciente em estado grave. Ribeirão Preto: FMRP; 2002: 90. Dissertação (Mestrado em Clínica Cirúrgica), Faculdade de Medicina de Ribeirão Preto. DatDef 03.12.2003.
41. Long CL, Schaffel N, Geiger JW, Schiller WR, Blakemore WS. Metabolic response to injury and illness: estimation of energy and protein needs from indirect calorimetry and nitrogen balance. JPEN J Parenter Enteral Nutr. 1979;3:452 -456.[Abstract/Free Full Text]
42. Singer JA, Singer P. Measured resting energy expenditure in the normal, overweight and obese Israeli population. Rev Bras de Nutr Clín. 2005;20:6 -8.
43. Nonino CB. Calorimetria indireta x Harris-Benedict: determinação, validação e comparação para cálculo da taxa metabólica de repouso em obesos grau III. Ribeirão Preto FMRP; 2002. Dissertação (Mestrado em Clínica Médica), Faculdade de Medicina de Ribeirão Preto. DatDef. 22/03/2002.
44. Ribeiro PC. Nutritional therapy in sepsis. RBTI.2004; 16:175 -178.

Journal of Parenteral and Enteral Nutrition, Vol. 32, No. 2, 176-183 (2008)
DOI: 10.1177/0148607108314761


CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Hoher, J. A. Articles by da S. Moreira, J. Search for Related Content PubMed PubMed Citation Articles by Hoher, J. A. Articles by da S. Moreira, J. Pubmed/NCBI databases Medline Plus Health Information Diets Social Bookmarking                   What's this?