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Nutrition of intensive care patients is often complex and challenging due to metabolic changes. For this reason nutritional support adapted to the metabolic state is of key importance to avoid hyper- or hypoalimentation and thus has direct impact on the prognosis. Target parameters might be beneficial to establish an adequate and differentiated nutritional strategy but thus far concerning single nutritional components evidence-based data are only available for adjusting blood glucose levels. Furthermore, an early enteral nutrition is of major prognostic importance. In practice a supplementary parenteral support is often required to provide adequate calorie supply. Monitoring of residual gastric volume as a tool to regulate an effective enteral nutrition might possibly become less important due to recent study data.

The reference method for determining resting energy expenditure (REE) in clinical nutrition practice is measurement by indirect calorimetry; however, indirect calorimetry has some limitations, is expensive and not widely available. Therefore, the most used methods to estimate the caloric requirements in intensive care patients are predictive equations. The Harris-Benedict equations (HBE) are the most common formulae in the clinical setting. The SenseWear(®) armlet (SWA) is a noninvasive device that monitors skin temperature, heat flux, galvanic skin response and movement. These data as well as anthropometric characteristics are used to calculate REE. The aim of this study was to evaluate the levels of agreement and interchangeability of REE estimated by HBE (EEHBE) and measured by SWA (EESWA) in normometabolic patients after elective bowel resection with laparotomy. Furthermore, postsurgical pain therapy by continuous thoracic epidural anaesthesia (t-PDA) was compared with continuous intravenous pain therapy regarding EESWA in these patients.After obtaining approval by the ethics committee and written informed consent 57 patients participated in the study procedures. A total of 50 patients (23 male, 27 female) were finally included in the data analysis because 7 patients did not meet the criterion of80% on-body time of the SWA. Additional (a priori) exclusion criteria were metabolic or cardiopulmonary decompensation or postoperative mechanical ventilation. Before induction of general anesthesia 26 patients received a thoracic epidural catheter. Immediately after surgery the SWA was placed on the right upper arm of each patient for 24 h. A continuous pain therapy was started either an epidural application of ropivacain 0.2% and sufentanil or in the other 24 patients an intravenous infusion of metamizol and tramadol.The data showed good agreement between EESWA and EEHBE. The mean on-body time was found to be 22.94±4.77 h. There were no significant differences between EESWA and EEHBE (p0.05) corresponding to a high Pearson's coefficient of correlation of 0.985. The mean bias (EESWA-EEHBE) was -0.569±0.378 kcal/kgBW/24 h reflecting a minimal systematic underestimation of REE by SWA of -2.9% compared to EEHBE. The Bland-Altman plot shows interchangeability of EESWA and EEHBE. It was noted that 94% of the data points (47 out of 50 patients) were within ±2 SD and the remaining 3 data points were lying close to the 95% interval. The same results (no significant differences between EESWA and EEHBE) were obtained after differentiation of EEHBE into low (18 kcal/kgBW/24 h, n=9), medium (18-21 kcal/kgBW/24 h, n=30) and high (21 kcal/kgBW/24 h, n=11) energy ranges. There were no significant differences in EESWA regarding postsurgical pain therapy regimens.The SWA showed reliable concordance with daily REE estimated by HBE in normometabolic postsurgery patients. This noninvasive, convenient and easy to handle device may be helpful in determining energy requirements as part of metabolic monitoring. Further research is needed to validate the method in patients with severe metabolic disturbances. The energetic requirements of patients with postoperative t-PDA were not different from those with intravenous pain therapy.

Using indirect calorimetry (IC), required energy demand may be determined. The SenseWear (SW) armband uses skin temperature, galvanic skin response, heat flux, and a 2-axis accelerometer to estimate daily energy expenditure (EE). The aim of the present study was to evaluate accuracy of the SenseWear measurements in critically ill and ventilated patients.After approval of the local ethics committee and written informed consent, critically ill and ventilated patients were enrolled. During a 24-h study period EE was continuously measured using the SW armband (standardized position at right upper arm); an IC was performed additionally. Measurement bias (DeltaEE) was calculated as DeltaEE=EE(SW)-EE(IC). Daily energy expenditure of both techniques (IC vs. SW) was compared using regression analysis and the Bland Altman method. The t-Test for paired samples was used for statistical analysis, p0.05 was considered statistically significant.In total, 23 critically ill and ventilated patients (17 male, 6 female; means: 59.9+/-17.3 years; body mass index 28.0+/-6.3 kg/m(-2)) were investigated. A mean bias of DeltaEE=-565.65+/-1,748.07 kJ (-135.0+/-417.2 kcal) [range: -4,709.56+/-2,224.89 kJ (-1,124 to +531 kcal); p=0.3547] was calculated. Bland-Altman analysis revealed that SW slightly overestimates IC energy expenditure for critically ill patients in the hypo- and normocaloric range [7,123 kJ/24 h: DeltaEE=+644.42+/-1,038.70 kJ (1,700 kcal/24 h: DeltaEE=+153.8+/-247.9 kcal); p=0.0838], but significantly underestimated IC values in the hypercaloric range [10,056 kJ/24 h: DeltaEE=-2,679.09+/-1,698.63 kJ (2,400 kcal/24 h: DeltaEE=-639.4+/-405.4 kcal); p=0.0098].The SenseWear armband is non-invasive, convenient and easy to handle, but has a significant measurement bias in the hypercaloric range. Although IC is still best suited to determining metabolic need in intubated patients, measurements with the SenseWear armband provide significant advantages, e.g. in non-intubated patients, and give a fair estimation of daily energy expenditure when used alone.

We investigated the practical use of indirect calorimetry for the individual nutritional support of preterm infants in order to answer the question whether it is possible to reliably calculate energy expenditure, fat and carbohydrate oxidation in preterm infants individually by using the results of a timed 6-hour-measurement of oxygen consumption and carbon dioxide production.Measurements were performed in 20 preterm infants (gestational age 30.2 +/- 0.6 weeks, birth weight 1.09 +/- 0.07; mean +/- SEM) at a mean postnatal age of 25 +/- 4 days and with a body weight of 1.35 +/- 0.06 kg.Carbon dioxide production (24 h-VCO2), oxygen consumption (24 h-VO2) and respiratory quotient (24 h-RQ) were measured by indirect calorimetry for 24 hours using the Deltatrac II metabolic monitor (Datex, Helsinki, Finland). Additionally, 6 h-VCO2, 6 h-VO2 and 6 h-RQ were determined by measurement over 6 hours. The patients' energy expenditure, fat and carbohydrate oxidation were calculated from VCO2 and VO2 measured over a 24 hour- and 6 hour-period with or without consideration of urinary nitrogen excretion (NU).If NU was not included in the calculation of energy expenditure, the values differed by maximally 1.1% from the calculations including NU. The correlations between the 24 h-RQ and the calculated 24 h-fat or 24 h-carbohydrate oxidation values were statistically significant (r = -0.99; p = 0.0001 and r = 0.773; p = 0.0002 respectively). However, in individual patients, it was not possible to predict 24 h energy expenditure, fat and carbohydrate oxidation of preterm infants using values determined by 6 h indirect calorimetry.The determination of the urine-nitrogen excretion is not necessary for calculation of energy expenditure of preterm infants. It is possible to estimate fat and carbohydrate oxidation of preterm infants by the measured 24 h-RQ, but 6 h indirect calorimetry is not accurate enough for calculating the individual nutritional needs of preterm infants in clinical practice. Indirect calorimetry over 24 h may be helpful in the management of selected patients with nutritional problems.

A trial on total metabolism was conducted in eight nonpregnant, nonlactating sows over eight periods, each of 16 days duration, to measure potential fatty acid induced thermogenesis. During the first and last experimental periods, the animals received a basal ration which just covered the energy maintenance requirement. In the second to seventh periods supplements of olive oil, fish oil, or puffed wheat starch as reference nutrient were added to the diet in random sequence at two levels up to 50% above the maintenance requirement. All rations were calculated with reference to the sows' initial weight and remained quantitatively unchanged throughout the experiment. The animals were fed twice daily. During each metabolism period a complete energy balance was assessed for all sows by means of collection technique (feed, feces, urine), and 48-h measurements of the gas exchange in a respiration chamber. The sows' body mass increased linearly during the course of the experiment by 5.8 kg per period. The three supplement types had no influence on the animals' final body weight, wich averaged 205.5 kg with the starch supplement, 204.8 kg with olive oil, and 205.8 kg with fish oil. Energy digestibility (DE/GE) was 100% for all three supplements, and metabolizability of energy (ME/GE) one percentage point less. Carbon and energy depositions showed a pronounced linear relationship to the level of supplementation and were also influenced by the type of supplement. Heat production was 20.9 MJ/d after feeding the basal ration alone and, taking the average of the two supplementation levels, 21.6 MJ for the starch supplement, 21.0 MJ for olive oil, and 20.6 MJ for fish oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen uptake (VO2) and carbon dioxide elimination (VCO2) can be measured with an indirect calorimeter, this method is well established in routine monitoring of ICU patients to evaluate metabolic state as a reflection of stress. In various experimental studies it was demonstrated that anaesthetics can influence whole-body metabolism. The purpose of this study was to examine whether indirect calorimetry can be used intraoperatively during routine anaesthesia and whether presumable changes in metabolism can be detected immediately. Abdominal aortic cross-clamping changes circulation, nutritional supply of the lower extremities and thus VO2 and VCO2. We therefore used this operation for our study. METHOD. Eleven patients, mean age 64 years, undergoing reconstruction of the aortic bifurcation, were studied. After premedication with piritramid and atropine, total intravenous anaesthesia (TIVA) was performed with fentanyl and midazolam after an induction with thiopental. Patients were ventilated with a Servo-Ventilator 900 D and a constant FiO2 of 0.5, without N2O. Routine monitoring consisted of ECG, pulsoximetry, CVP and continuous AP. VO2 and VCO2 were measured with a Deltatrac (Datex), and data were registered every minute. For statistical evaluation we used a Wilcoxon-Ranksum test for matched pairs, p0.05 was considered significant. Data from specific time (5 min after intubation, 5 min before clamping; 5, 10 and 15 min after clamping, before declamping and 5 and 10 min after declamping and at the end of surgery) were calculated. In addition to absolute values, we compared the measured VO2 and VCO2 to baseline (5 min before clamping = MP2). RESULTS. Mean operating time was 139 min +/- 37; aortic cross-clamping time for the first extremity was 38 min and 55 min for the second. As expected, there was a significant decrease in VO2 (90% of baseline) and VCO2 (75% of baseline) during aortic cross-clamping. After declamping VO2 again rose to 110% of baseline, or to 103% for the second limb. VCO2 increased to only 90% and 82%, respectively. At the end of surgery VO2 reached baseline, whereas VCO2 remains at 83%. The respiratory quotient VCO2: VO2 was markedly reduced from 0.95 +/- 0.156 to 0.73 +/- 0.06 during surgery. The Deltatrac showed every change in VO2 without delay; changes in VCO2 seem to occur somewhat retarded. DISCUSSION. Aortic cross-clamping leads to a marked decrease in VO2 and VCO2 reflecting the temporary reduction in whole-body metabolism. Declamping results in a compensatory rise, especially in VO2. VCO2 seems to increase less after declamping, perhaps due to the CO2 pool of the organism or to a change in metabolism from carbohydrate to mainly fat oxidation. The results of this study demonstrate that indirect calorimetry can easily be performed during anaesthesia and surgery. Preconditions are a non-rebreathing system without airleak, constant FiO20.6 and no use of nitrous oxide.

The energy and nitrogen metabolism of pregnant sows was measured with the method of indirect calorimetry in dependence on the number of gestation (1,2 and 4), on the energy supply (120, 100 and 80% of the requirement recommendation) and on the gestation stage. Values of maintenance requirement and of energy and nitrogen utilization for body deposition were calculated on the basis of results of energy and nitrogen metabolism. The energy maintenance requirement increased from 389 to 435 and 473 kJ metabolizable energy per kg LW0.75.d with rising number of gestation. The heat production increased from 85th to 115th day of gestation by 6%. The efficiency of the partial energy utilization for the energy deposition amounted to 66% on the average. The efficiency of the partial utilization of digestible nitrogen for the nitrogen deposition was calculated to 75%. The nitrogen maintenance requirement values amounted to 0.5 and 0.4 g digestible nitrogen per kg LW0.75.d in the 1st and 2nd half of gestation.

The aim of the experiments was to work out new results for a factorial derivation of energy and protein requirement. The experiments were carried out according to a 3 x 3 factorial experimental plan with 3 variants of litter number (1, 2 and 4, age of sows) and 3 variants of energy supply (120, 100 and 80% of the norm of pregnancy, continued in lactation with 80, 100 and 120%). Methods of the indirect calorimetry and the slaughtering technique were used. The mean cumulative live weight changes of the sows for the 9 experimental variants amounted from 13.1 to 63.2 kg for the 115 days of pregnancy and from -17.0 to 6.8 kg for the first 26 days of lactation. The chosen variation of energy supply of pregnant and lactating sows had no relevant effect on the reproductive performances, measured by litter size, weight of conception products, litter weight at birth and the quantity of milk per sow and day respectively. In comparison with the sows of litter number 1 the sows of litter number 2 and 4 had higher litter weights at birth and higher milk quantities.

The influence of litter number (1, 2 and 4, age of sows) as well as gestation and lactation stage of sows on the chemical composition and on the quantities of protein and fat of their bodies was investigated. The slaughter of 46 pregnant, 18 non-pregnant and 17 lactating sows were carried out at the 1st, 56th, 84th, 98th, 105th and 113th day of gestation, 113th day of experiment (non-pregnant sows) and 26th day of lactation. The results were related to the sows' energy supply (120, 100 and 80%) with equal supply of protein, vitamins and minerals. Within the tested litter numbers the chemical composition of the bodies was nearly constant during the whole time of gestation and lactation. A good agreement existed for the chemical composition of the sows' bodies of litter number 1 and 2. In comparison to them the bodies of litter number 4 contained more protein and less fat per kg dry matter. The quantities of body protein and fat increased in the gestation and decreased in the lactation period, in each case the quantities of fat exceeded than the quantities of protein. The quantities of body protein increased with higher litter number. The quantities of body fat increased from litter number 1 to 2 and were nearly equal in the sows of litter numbers 1 and 4. Within one litter number the amounts of body protein and fat attained the same level in pregnant, non-pregnant and lactating sows.

Male Wistar rats were fed in the live weight range between 70 and 200 g in periods alternately for maintenance and weight gain (semi ad libitum). The diets contained 10, 40 and 70% crude protein, resp., the ambient temperature was 30 degrees C. In agreement with two previous experiments 2 different feed regimes were used. Whereas in the first growth phase (up to about 150 g live weight) the supply of protein was constant for each group, in the second growth phase the protein level was changed between the groups from one period to the other. The energy metabolism on the feeding level of maintenance was measured by indirect calorimetry. At both feeding regimes a dependence of energy maintenance requirement on the protein level of feeding was established. The differences in the maintenance requirement between the 10% and 70% protein level and in the first growth phase also between the 10% and 40% protein level corresponded on average to a growth phase the expected values of which result from the different efficiency of ATP synthesis in the oxidative degradation of nutrients. It follows that--in accordance with the previous findings--the feeding regime does not influence the ratio of energetic utilization of nutrients in the maintenance metabolism of growing rats under the experimental conditions used by us. Further the results of all our studies on the dependence of the energy maintenance requirement of growing rats on the nutrient composition are summarized. We conclude that a dependence on the protein-carbohydrate ratio of the diet according to the different efficiency of ATP synthesis in the protein and carbohydrate catabolism can be reproducibly established by our experimental methods only then, if more than 50% of the energy maintenance requirement are covered from protein energy.

Presentation of a newly conceived measuring instrument to determine the energy expenditure of critically ill patients at the bedside by means of indirect calorimetry. The special advantages of the measuring instruments are easy handling, little maintenance and very low working expenses and prime costs. The accuracy of measurement is considerable nd is comparable with that of other measuring methods, as has been established by an extensive validation.

There is always a distinct increase in energy expenditure in postoperative, posttraumatic and septic patients. In order to predict this increase in energy expenditure an enormous number of formulas have been developed. However, the problem with all these formulas is that they cannot sufficiently take into account the peculiarities of the underlying disease, the general and nutritional condition or the varying influence of the phase of disease. Furthermore, all these patients continuously show a considerable change in body weight which can be attributed to a shifting of the water balance. In all of these cases any calculation of energy expenditure based on body weight will inevitably be incorrect. Therefore, it is recommended that predicting formulas only be used as orienting guidelines in all uncomplicated postoperative or posttraumatic courses. In patients with multiple injuries or septic complications the real energy expenditure should be measured by indirect calorimetry in order to adapt energy intake during enteral or parenteral nutrition to the very different metabolic situations.

The authors have investigated the relationship between total parenteral nutrition (TPN) under indirect calorimetry and the development of fatty infiltrations of the liver in 21 surgical and traumatized patients. TPN was monitored by indirect calorimetry in order to balance lipid and amino acid intake. Glucose intake was adapted only when daily glucose utilization was higher than 150 g. Non protein respiratory quotient (npRQ) and respiratory quotient (RQ) remained below 0.9 during the whole study. The need for lipids was always significantly higher than the lipid intake up to the 5th day after operation or trauma. The need for carbohydrates was significantly lower than the intake of carbohydrates up to the 9th day after operation or trauma. In addition, the utilization of lipids was higher than the utilization of carbohydrates. After 2 weeks of TPN, no fatty infiltration of the liver could be detected by computer tomography and chemical analysis. The calorimetric monitoring of the TPN regimen and the individual adaptation of substrate intake might be responsible for the protection of the liver observed in this study.

The effects of two diets equal in protein content (12% of energy) but different in carbohydrates (80% of energy) or in fat (68% of energy) were studied in a changeover trial with 6 healthy young subjects. Each person was 2 weeks on each diet. Under the conditions of slight undernutrition and neutral temperature the balances of nitrogen, carbon and energy were assessed in 7-day collection periods, and according to 48-hour measurements of gaseous exchange (carbon-nitrogen balance method) by the procedures of indirect calorimetry. At isocaloric supply of metabolizable energy no differences were found in the retention of N, C and energy. The heat production calculated by indirect calorimetry was not significantly different with both diets. The lower body weight during the high-fat diet was due to higher sodium and water excretion. The high-fat diet resulted in lower fecal and higher urine excretion of nitrogen, but because of a compensative response no difference in nitrogen retention was observed between the two dietary regimens. The plasma concentrations of cholesterol, glucose and uric acid were higher with fat-rich diet; those of triglycerides were higher with carbohydrate-rich diet. The results demonstrate that the composition of the diet did not influence the energy balance.

During episodes of trauma carnitine-free total parenteral nutrition (TPN) may result in a reduction of the total body carnitine pool, leading to a diminished rate of fat oxidation. Sixteen patients undergoing esophagectomy were equally and randomly divided and received isonitrogenous (0.2 gN/kg.day) and isocaloric (35 kcal/kg.day TPN over 11 days without and with L-carnitine supplementation (12 mg/kg.day). Compared with healthy controls, the total body carnitine pool was significantly reduced in both groups prior to the operation. Without supplementation carnitine concentrations were maintained, while daily provision of carnitine resulted in an elevation of total carnitine mainly due to an increase of the free fraction. Without supplementation the cumulative urinary carnitine losses were 11.5 +/- 6.3 mmol corresponding to 15.5% +/- 8.5% of the estimated total body carnitine pool. Patients receiving carnitine revealed a positive carnitine balance in the immediate postoperative phase, 11.1% +/- 19.0% of the infused carnitine being retained. After 11 days of treatment comparable values for respiratory quotient, plasma triglycerides, free fatty acids, ketone bodies, and cumulative nitrogen balance were observed. It is concluded that in the patient population studied here carnitine supplementation during postoperative TPN did not improve fat oxidation or nitrogen balance.

Precondition for the evaluation of indirect calorimetry data by standard procedures is an undisturbed physiological metabolic situation. Metabolic changes in stress metabolism, which are a reduction of enzyme activity, increased rates of gluconeogenesis und ketogenesis, and simultaneous occurrence of lipolysis and lipogenesis cannot be considered by those calculations. Various problems concerning the evaluation of data obtained on traumatized patients confirm the presumption that standard procedures are not suitable in the case of posttraumatic metabolic disturbances. Therefore, we developed two computer-supported metabolic models, which assume a reduced activity of the three key enzymes: pyruvate dehydrogenase (PDH), phosphofructokinase (PFK) and citrate synthetase (CS). The blocked metabolites are bypassed to gluconeogenesis, lipogenesis and in so called 'pools' ('glucose-pool', 'acetyl-pool'). In addition, a detailed simulation of amino acid degradation is permitted. The models were applied to evaluate indirect calorimetric data of four patients, which could not be evaluated by standard procedures. It was shown that an evaluation of all data was possible by at least one model. All enzymes presented a slight to complete blockade. The calculated maximal activities of PFK was 1.59 mol/d, of PDH 6.31 mol/d and that of CS 6.55 mol/d. These activities were far below the values of normal human beings. As a result of these enzyme inhibitions, high rates of gluconeogenesis (max. 387 g/d) and lipogenesis (max. 511 g/d) as well as high values for the glucose-pool (max. 387 g/d) and the acetyl-pool (max. 641 g/d) were calculated. The interpretation of the pools was difficult. Renal elimination of the metabolites was not found in our patients, an accumulation was impossible for osmotic reasons. Therefore, despite the catabolic hormonal character of stress metabolism, storage as molecules of high molecular weight should be taken into account.

Normal enteral feeding cannot be maintained after trauma. Post-aggression metabolism or socalled "flow phase" usually results from hormonal changes, including rise in catecholamine and cortisole, drop in testosterone as well as T3 and T4, and relative hGH deficit. Glucose intolerance, increased demand for energy, and catabolism are the consequences along with reduced protein uptake and increased protein breakdown with all associated complications. Indirect calorimetry is an important method to determine energy requirements and, above all, is used to monitor nutrition and other therapeutic interventions. Substrate requirement and distribution of substrate supplies are discussed in some detail. All-in-one solutions and tube feeding have quite often proved helpful in providing patients with sufficient and properly adapted nutrition. On top of adequate nutrition, catabolism is therapeutically controlled by medication, using beta-blockers and hGH. The need for supervision of nutrition is also discussed.

For the evaluation of indirect calorimetry, elements are used, which specify the relation between nitrogen (N) excretion and amount of oxidized amino acids (AS/N) and between nitrogen excretion and oxygen-/carbon dioxide-exchange of the corresponding amounts of amino acids (O2/N, CO2/N). These elements are only valid for the amino acid mixture which was used for their determination, and only under the condition of complete combustion of deaminized amino acid skeletons. We developed a computer program, which is able to simulate complete oxidation, maximal gluconeogenesis, and maximal lipogenesis for a given amino acid mixture of any composition. The parameters AS/N, O2/N and CO2/N were calculated by the program for various parenteral amino acid solutions. Range of error was determined exemplarily for the use of standard parameters. The calculations demonstrate errors up to 50% for the calculation of substrate turnover in indirect calorimetry, depending on composition and actual metabolism of amino acid mixtures. As long as these influencing factors are not known in stress metabolism, we recommend to use those elements, which were calculated for the amino acid solution in use, assuming complete combustion.

A new device for continuous measuring oxygen uptake (VO2) and carbondioxide elimination (VCO2) in artificially ventilated or CPAP-system breathing children has been developed. A dual-channel analyzer system based on zirconiumoxyd cells measures oxygen fractions. This allows not only single measurements but also continuous determination of fraction differences for oxygen (delta FO2) (accuracy +/- 0.003 Vol%). Carbondioxide is measured by infrared absorption. A mixing device for inspiratory gas was designed to smooth fluctuations of inspired oxygen fractions almost completely. The reliable sampling system for expiratory gases has already been described [19]. The breathing-e.g. ventilating-system was modified in such a way that the total gas flow is independent of mode and breathing volume (equally 15 l/min). For which purpose we use a self aspirating, time-cycled, volume limited respirator or a high-flow-CPAP-system. The prototype described ran test performances on a specially developed pneumatic metabolic-lung-model. This new lung model enables free choice of respiratory quotient (R) by independent setting of O2-uptake and CO2-elimination. Under these controlled laboratory conditions gasvolume-balances correspond to expected values in children really as shown during simulated trials. In the metabolic-lung-model accuracy and reproduction averaged +/- 1% for VCO2. Both were independent of the mode of ventilatory support, FIO2, and R. Determinations of VO2 were more dependent on FIO2 and R. After computing primary data according to a special formula which equalizes differences between VI and VE the maximal error was +/- 7%. Maximum difference between preset and measured R-values ranging from 0.769 to 1.429 was -4.6%, determined at R = 1.429. By means of this independent test series insights into clinically expected measurement errors and dimensions of limits of accuracy could be demonstrated. It seems to be justified that our newly developed device for accurate measuring O2-uptake and CO2-elimination is highly recommendable for use in extremely difficult conditions as in ventilated children.

Indirect calorimetry was performed during the first five days after admission in 18 neurosurgical patients with isolated head - injuries (N = 7) and spontaneous intracranial hemorrhages (N = 11) to determine basal metabolic rates (BMR). In the study group each day BMR varied from 2143 +/- 636 kcal/day to 3371 +/- 1140 kcal/day. Most patients however showed BMR values between 2000 and 2500 kcal/day. Individually BMR values ranged from 60 to 340 percent of normal healthy individuals. Patients with isolated head - injuries showed significant higher metabolic rates than patients with spontaneous intracranial hemorrhages. The authors conclude that an caloric intake of 2000 to 2500 kcal/day is sufficient for parenteral nutrition and usually helps to avoid negative effects of hyperalimentation by overestimation of BMR in this special patient group.

By means of a measuring device based on the principles of indirect calorimetry, long-term recording of energy transformation in patients with cerebral tumours and cerebral traumas is performed. Contrary to the conception that the catabolic state in the postoperative/posttraumatic period corresponds to a negative balance between requirement and enteral/parenteral supply, it appears that, as a rule, the energy requirement is only 1 to 1 1/2 times higher than under normal conditions. During long-term measurement, clinical phenomena that are characterized by increased muscular activity (seizures, extension automatisms, extreme psychomotor excitations) show a daily requirement of maximal 3,500 kcal. Considering the clearly lower requirement, the change of the catabolic state by a high-caloric intake (5,000 and 6,000 calories/day) can only be due to an effect on the regulation of the metabolic processes.

Significant changes in oxygen uptake (VO2) and carbon dioxide output (VCO2) as well as resting energy expenditure (RMR) can be observed in critically ill patients. Reliable data, although needed by the clinician especially in long term ventilated patients, have not been obtainable so far. We developed a modular system which provides by means of mass-spectrometry, accurate reproducible results. Furthermore, the design of the gas sampling module minimalizes systemical failures in the expiratory branch. Two groups of polytraumatized patients (n = 10, n = 7 respectively) with different amounts of intravenous amino-acid support and identical energy supply were included in the study. During the first week all patients showed significantly elevated values for VO2 and VCO2 with a tendancy to increase. High amino-acid supply resulted in higher rate of gas exchange and disproportional increase in energy expenditure. Subsequently reduced carbohydrate intake was found to be effective in reduction of gas exchange earliest after 24 h. Oxidation rates for glucose and fat did not correspond to energy supply ratio of substrates. It can be stated that in polytraumatized patients amino-acid supply more than 75 g/24 h/m2 is not economical in terms of energy gains and is therefore not generally recommended. Reduction of carbohydrates in the weaning period of respirator in these patients is likely to be effective only in borderline cases and started early before weaning (greater than 24 h). Energy supply by means of carbohydrates should exceed the energy derived from fat supply in the nutritional regime according to oxidation rates in polytraumatized patients.

After the new device for measurement of oxygen uptake (VO2) and carbon dioxide elimination (VCO2) was tested in a pneumatic lung model, we investigated its clinical practicability. First the level of VO2 and VCO2 in the early postoperative phase was determined. Secondly we examined alterations in gasexchange caused by various intensive care activities. Whereby main concern was the change from mechanical ventilation to spontaneous CPAP-breathing. Ten children undergoing cardiac surgery (age: 10 days to 10 years) were included in the study. Three children were primarily investigated on the CPAP-system. Data from another six were collected under controlled ventilation as well as under spontaneous CPAP-breathing. One child had to be ventilated for a longer time (greater than 24 h). The change from mechanical ventilation to spontaneous breathing was accompanied with a temporary increase of VO2 and VCO2. As expected, all stressful factors like tracheal suction, pain or anxiety increased these two variables. Also some drugs showed remarkable changes. While marked increases under Normastigmine, Naloxone, and Dopamine could be observed, gas exchange was decreased under Morphine. However, heart rate showed no good correlation with VO2. We conclude that the developed prototype is a reliable device for measuring VO2 and VCO2. Our results suggest that spontaneous CPAP-breathing is not always accompanied with increased gas exchange. If there is an increased gas exchange, it may refer to transient changes during the adaption phase. Therefore, a continuous monitoring of VO2 and VCO2 over a longer period of time is necessary. Consequently the first phase after changing ventilatory support has to be viewed carefully. The heart rate in children, undergone cardiac surgery, is not a good predictor for determination of VO2 and thus for energy expenditure. This device allows to quantify accurately oxygen consumption and carbon dioxide elimination in ventilated children. Furthermore, alterations in metabolism and cardiopulmonary variables caused by intensive care and therapeutic interventions can be examined continuously. It seems to be a valuable tool for metabolic and cardiopulmonary monitoring in critically ill children.

There are two main reasons for assessing energy turnover individually and as accurately as possible; firstly, the marked variation in available data on the degree to which energy turnover increases after severe trauma, and secondly accumulating evidence of the potential dangers of an inappropriately high so-called "hypercaloric" substrate dosage, which exceeds energy requirements. The energy turnover of 50 polytraumatized intensive care patients was therefore measured by indirect calorimetry and compared with norm values. Comparison of the median values revealed an approximately 50% higher energy turnover in the polytraumatized cases than calculated basal levels. The median values of our patients all lay within a similar range, but for each individual case we found marked differences between the energy turnover as measured by indirect calorimetry, and that estimated from norm tables. The oxygen consumption and CO2 production rates of 10 polytraumatized ventilated patients, measured at short time intervals, showed only minimal variations during the course of 24 h. The separate measurements carried out at hourly intervals varied by less than 10% when compared to an 1-h period of observation between 11 and 12 a.m. The oxygen consumption of a group of 40 polytraumatized, ventilated intensive care patients receiving various different i.v. infusions and parenteral nutrition regimens was, with an average of 382 +/- 47 ml/min, much higher than physiologically normal values. The energy turnover rate of these patients was correspondingly much higher than that of a fit person at rest, despite the fact that the rates measured were relatively low when compared to values found in the older literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Energy requirement after major abdominal operations, as calculated according to the formula for basic energy expenditure by Harris-Benedict, was increased by 30% in the early and by 50% in the late postoperative period. Correlation of these calculated values to measurements by indirect calorimetry was good. Even more simply a good estimation of caloric requirements can be obtained by multiplication of the body weight with a factor 30. The development of septic complications does not increase considerably postoperative energy expenditure, however, the correlation between measured and estimated values becomes poor. As supposed from isotope studies measuring gas exchange for indirect calorimetry for one hour provides sufficiently stable results.

The noninvasive determination of the respiratory gas exchange (measurement of oxygen uptake and carbon dioxide delivery) permits the calculation of cardiac output by Fick principle and of the actual energy requirement of the patient (indirect calorimetry). A system is presented for the continuous measurement of oxygen uptake and carbon dioxide delivery, that bases on simple components, which are available on most intensive care units. The methodical problems are discussed and the improvement of the signal of the oxygen sensor by digital signal processing is described. Clinical measurements on 16 patients are presented, whose metabolic rate early after extracorporal circulation was measured. The results reveal, that 4.4 hours after ECC the metabolic rate is close to the calculated basic metabolic rate. They demonstrate the importance of indirect calorimetry as a future bedside monitoring routine.