Clinical validation of the Deltatrac monitoring system in mechanically ventilated patients

Objective To evaluate a monitor of pulmonary gas exchange (Deltatrac, Datex) in a clinical setting.Design After in vitro evaluation, comparison over 2 min between and values measured by the Deltatrac and the Douglas bag technique. Comparisons were also achieved over 8 h periods between the Deltatrac and a system using a mass-spectrometer.Setting Polyvalent intensive care unit (ICU 15 beds) in a 1200 bed general hospital.Patients Comparison with the Douglas bag technique in 10 patients undergoing controlled ventilation. Comparison with the massspectrometer system in 25 other patients undergoing controlled or pressure support ventilation.Measurements and results Compared to the results obtained by the Douglas bag technique, the bias (±2SD) for and was –3.5±26.6 and 6.1±12.7 ml·min^–1, respectively. By comparison with the mass-spectrometer system, the bias for and RQ was –5.8±16.0 ml·min^–1 and 0.018±0.048, respectively. No drift between the two systems was observed over time.Conclusions The Deltatrac appears suitable for and measurements in ventilated patients and equivalent to a mass-spectrometer system for long term measurements.Supported by Contrat PRA (CNRS/HCL) and Contrat BQR 1993, Université Claude Bernard de Lyon     

Metabolic and respiratory effects of enteral nutrition in patients during mechanical ventilation

The effect of enteral feeding on O₂-consumption ( ) and CO₂-production ( ) was studied in 9 ventilator-dependent patients, who were in a stable condition without signs of hypermetabolism. Resting energy expenditure (REE) in postabsorptive state was assessed and enteral feeding was started by continuous drip (480 kcal carbohydrate, 360 kcal vegetable fat and 160 kcal milkprotein: 6.4 g Nitrogen/ 1000 ml). Patients were given a moderate and a high caloric intake: 1.5 and 2.0 times REE. and were measured for a 24 h period, beginning 7 h after the start of the dietary intake. Significant greater increases in , and RQ were found during high caloric intake compared with the moderate caloric intake. , and arterial blood-gases were measured in 4 patients during weaning from the ventilator. The increase in induced by the high caloric feeding resulted in a rise in arterial CO₂ tension (P_aCO₂) and respiratory distress. High caloric enteral nutrition can cause a significant increase in inducing respiratory distress during weaning from the ventilator in patients with limited pulmonary reserves. Moderate caloric nutrition will be preferable to these patients in order to facilitate the weaning.     

A new paediatric metabolic monitor

Objective A paediatric option for the measurement of and (20 to 150 ml/min) has recently been introduced for the adult Deltatrac metabolic monitor (Datex Instrumentarium, Finland) to use in ventilated and spontaneously breathing children. This paper describes a laboratory validation of the paediatric option for ventilated children with regard to the influence of respiratory variables. Design Respiratory variables were varied within the following ranges: FIO₂ 0.21–0.8, (DFO₂) 0.01–0.05, , V_T 8–300 ml, RR 10–50/min, P_aw 10–60 mbar, relative humidity 10% and 60%, and resulted in 107 test situations. Setting Gas exchange was simulated by injection of nitrogen and CO₂ at a RQ close to 1. Patients or participants Different situations of paediatric patients ventilated in controlled mode were simulated on a gas injection model. Interventions Respiratory and metabolic variables were varied independently to result in a range of 8 to 210 ml/min of and . Measurements and results Reference measurements were carried out by mass spectrometry and wet gas spirometry. The mean difference for all tests ranging from 20 ml/min to 210 ml/min was −2.4% (2SD=±12%). The respective difference was −3.2% (2SD=±23%). Measurement agreement for in neonatal respirator treatment (20–50 ml/min) compared to older children (50–210 ml/min) showed a mean difference of −3.9% (2SD=±26%) versus −2.8% (2SD=±20%). The respective differences for were −7.1% (2SD=±7%) versus +0.4% (2SD=±10%). The mean difference for as well as indicated a high systematic agreement of both methods. The variability (±2SD) in measurement is acceptable for all applications. The overall variability in measurement (2SD=±23%) can be reduced by exclusion of all tests with a and DFO₂ below 0.03. This results in a mean difference of −3.2% (2SD=±13.7%). Conclusion Within this limitation the paediatric measurement option seems to introduce a valuable method for clinical application in paediatric intensive care medicine.     

Influence of SIMV plus inspiratory pressure support on\dot V_A /\dot Q distributions during postoperative weaning

Since the introduction of synchronized intermittent mandatory ventilation (SIMV) several advantages have been attributed to this ventilatory mode, one of them being a more homogeneous distribution of ventilation and perfusion than during controlled mechanical ventilation (CMV). Up to now no data are available to confirm whether this is true when SIMV is used in combination with inspiratory pressure support (IPS). Therefor, we compared the influence of CMV and SIMV+IPS on the distributions of ventilation and perfusion in 9 patients undergoing weaning from postoperative mechanical ventilation. Continuous distributions of ventilation and perfusion were assessed using the multiple inert gas elimination technique (MIGET). SIMV+IPS did not induce any change in the hemodynamic or oxygenation parameters, in particular CI and PaO₂ remained constant. Physiological dead space increased, but PaCO₂ remained unchanged due to increased minute ventilation (from 9.5±0.9l·min^–1 to 11.3±1.2l·min^–1). The perfusion distributions remained unaltered; there was no change in nor in the perfusion of the low lung regions. This result was underscored by the unchanged dispersion of the perfusion distribution (log ). The increased was caused by increased inert gas dead space (from 22.0±9.6 to 26.8±8.7%) which was accompanied by increased ventilation of lung regions with high ratios ( ) in 3 patients. These results show that in our group of patients partial removal of CMV together with pressure support assistance of spontaneous ventilation did not induce a clinically significant loss of the efficiency of the breathing pattern. Since the unchanged hemodynamic parameters were accompanied by increased minute ventilation, arterial blood gases did not deteriorate. Hense, SIMV+IPS proved to be useful for weaning from postoperative mechanical ventilation.Supported by Deutsche Forschungsgemeinschaft (Fa 139/1-2)     

Measurement and interpretation of maximal oxygen uptake in patients with chronic cardiac or circulatory failure

Rapidly responding gas.analyzers have simplified the monitoring of oxygen uptake in the clinical exercise laboratory. An incremental, exhaustive, upright exercise test can be safely used to determine the, plateau in oxygen uptake during exercise, ormaximal , in patients with chronic cardiac or circulatory failure. We define in these patients as an increase in of less than 1 ml/min/kg despite an increment in work load. The value for indicates the patient's aerobic capacity; it also predicts the maximal cardiac output during exercise and therefore serves as an estimate of cardiac reserve and of the severity of cardiac or circulatory failure. Symptom-limited during exercise, termedmaximum oxygen uptake but more appropriatelypeak , bears no relationship to . The two terms should not be used interchangeably.     

Metabolic and hemodynamic response to hyperventilation in patients with head injuries

The effects of controlled moderate hyperventilation (paCo₂∼31 mmHg) on cardiovascular parameters and whole-body-oxygen-uptake ( )was studied in 10 patients with head injuries, who were unconscious and artificially ventilated at the time of the investigation. was measured with the Beckmann Metabolic Measurement Cart and also calculated from cardiac output and arterio-mixed venous oxygen content difference. A mean increase in (+19.6% of control) was observed after 2 h of hyperventilation. Cardiac output remained unchanged. This resulted in a decrease of venous oxygen content and impaired full oxygenation of the blood. Our results indicate that hyperventilation should not be a routine procedure. Close monitoring of arterial and venous blood gases is recommended, when hyperventilation is applied.     

Outcome prediction in critically ill patients by means of oxygen consumption index and simplified acute physiology score

Both oxygen consumption index ( ) and simplified acute physiology score (SAPS) are reported to be reliable predictors of the ultimate out-come in critically ill patients. The purpose of this study was to verify whether survivors and nonsurvivors have different and whether the prognostic potency of SAPS can be improved by addition of as a supplemental physiological variable. In 50 mechanically ventilated surgical ICU patients with heterogenous underlying diseases, SAPS was calculated and was determined by continuous 24-h measurement of oxygen consumption. The of survivors and nonsurvivors were not significantly different (p>0.05), which is in contrast to the results of earlier studies. This contrast may be explained by a difference both in methods of and in study populations. SAPS was significantly lower in survivors than in nonsurvivors (p(0.005) and was able to classify the patients correctly into groups of increasing probability of death. However, SAPS failed to be a helpful prognosticator in the individual patient. The addition of to SAPS as a supplemental physiological variable did not substantially improve the prognostic potency. Because a higher did not necessarily indicate a better survival chance, there is no argument for therapeutic interventions aimed exclusively at increasing , as suggested previously.     

Oxygen consumption after cardiac surgery —a comparison between calculation by Fick's principle and measurement by indirect calorimetry

Oxygen consumption calculated by Fick's principle (c ₂) was compared to oxygen consumption measured (m ₂) by indirect calorimetry (Deltatrac Metabolic Computer) in 10 patients in the post-operative period after cardiac surgery. For 50 pairs of measurements the mean difference (m ₂–c ₂) was 34±27ml/min·m². The limits of agreement were –20ml/min·m² to 88ml/min·m². These results showed that c ₂ and m ₂ were not interchangeable in this study.     

Reflection of differential pulmonary perfusion in polytrauma patients on differential lung ventilation (DLV)

Seventeen polytrauma patients with asymmetric pulmonary contusion were treated with differential lung ventilation (DLV). The ratios of differential values of end-tidal CO₂ concentration (ETCO₂) and CO₂ excretion ml/min ( ) were compared as indirect parameters for differential pulmonary perfusion. Both CO₂-derived methods indicated asymmetry after starting DLV suggesting asymmetric pulmonary perfusion as a consequence of contusion. Prior to stopping DLV a significant improvement in asymmetry was indicated by the differential ratios of ETCO₂ and values. The ETCO₂ ratio increased from 0.74±0.17 to 0.88±0.10, the ratio from 0.57±0.23 to 0.86±0.11. In two patients with very severe contusion who underwent bilobectomies a marked difference between the ratios of ETCO₂ and was observed. It is concluded that differential measurement of CO₂-derived variables may be useful in indicating differential perfusion in clinical practice on DLV. In very severe asymmetric contusion ETCO₂ ratios may underestimate the differential perfusion ratio.     

Measurement of tissue perfusion by oxygen transport patterns in experimental shock and in high-risk surgical patients

Survivors of high-risk general (noncardiac) surgery were observed to have cardiac index (CI) values averaging 4.5 l/min·m², oxygen delivery ( O₂) of >600 ml/min·m², and oxygen consumption ( O₂) of 170 ml/min·m². In contrast, these values were relatively normal in patients who subsequently died. A very early predictive index based on these observations was found to predict outcome in 94% of high-risk patients. The hypotheses that increased- O₂ and O₂ in the survivors represent compensatory physiologic responses and that these values were appropriate therapeutic goals were tested in prospective randomized clinical trials and found to reduce mortality and morbidity significantly. The optimal goals were more easily attained with colloids, red cells, dobutamine, and vasodilators, according to their capacity to improve tissue perfusion, as reflected by increased flow and oxygen transport. The extremely complex interactions between- O₂ and O₂ are reviewed.     

Plasma catecholamines and oxygen consumption during weaning from mechanical ventilation

Previous studies on oxygen consumption ( ) during weaning from mechanical ventilation assumed that an increase in ( ) reflected oxygen consumption by respiratory muscles ( ), and proposed as a weaning predictor. We measured CO₂ production ( ) and plasma catecholamines in 20 short-term ventilated patients during weaning by SIMV and CPAP. as a percentage of during spontaneous ventilation ( %) ranged from 4.8% to 41.5%. also increased and correlated with . Plasma adrenaline and noradrenaline increased significantly to levels known to produce considerable increases in metabolic rate. Mean arterial pressure and heart rate concomitantly increased, but spontaneous minute ventilation decreased. Thus, since the increased plasma catecholamines are calorigenic, the assumption that represents is incorrect. Although mean % of successfully weaned patients was significantly less than that of failure-to-wean patients, the wide scatter of individual values in the latter group excludes % as an accurate weaning predictor.     

Oxygen cost of breathing for assisted spontaneous breathing modes: Investigation into three states of pulmonary function

Objective We investigated the effects of continuous positive airway pressure (CPAP) and pressure support ventilation (PSV) on the oxygen cost of breathing ( O₂resp) for different states of pulmonary function. Additionally O₂resp was measured during spontaneous breathing.Design This was done in a controlled and prospective study. Ventilatory modes were applied randomly.Setting Measurements were performed in a quiet room on volunteers (VOL) and inpatients treated for chronic obstructive pulmonary disease (COPD). Post-operative patients after aortocoronary bypass surgery (ACB) were studied on the cardio-thoracic intensive care unit just before and after extubation.Patients Healthy volunteers (n=14), postoperative patients after aorto-coronary bypass surgery (n=15) and patients with COPD (n=9), xFEV₁ 47.7%) were the objects of study.Interventions Demand flow CPAP (5 mbar) and PSV (7 mbar, PEEP 5 mbar), using the Hamilton Veolar ventilator, were investigated in comparison to spontaneous breathing.Measurements and results O₂ measured by a Datex Deltatrac metabolic monitor. O₂resp was calculated by subtraction of total oxygen uptake O₂tot) in controlled mode ventilation (CMV) from that in the respective spontaneous breathing mode. For VOL and COPD patients who were not intubated, a CPAP facemask connected to a short 7.5 mm tube was used as connection to the ventilator. Breathing spontaneously under a canopy system VOL showed a VO₂resp of 4.5±4.0% compared to 9.2±3.5% for ACB and 15.4±7.7% for COPD. CPAP changed the VO₂resp to 7.8±3.9%, 12.0±4.0% and 9.1±3.6% respectively. PSV reduced the O₂resp to 7.9±3.8% in ACB and 7.7±5.5% in COPD.Conclusions This investigation confirms findings that postoperative patients have a mild increase in O₂resp. COPD exhibit the highest increase in VO₂resp. Tracheal tubes, masks and CPAP on a demand flow apparatus increases O₂resp in volunteers and postoperative patients after cardiac surgery. The same amount of CPAP in contrary reduces O₂resp in patients with COPD. Pressure support ventilation can offset the additional O₂resp induced by CPAP but at the same level does not further reduce O₂resp in COPD patients.     

Estimation of cardiac index by means of the arterial and the mixed venous oxygen content and pulmonary oxygen uptake determination in the early post-operative period following surgery of congenital heart disease

Objective To assess the reliability of estimation of cardiac index based on the mixed venous oxygen saturation and methods of improving the estimation of cardiac index.Setting PICU in an university hospital.Design In the post-operative period following complete repair of congenital heart disease we carried out 55 measurements of blood gases in 25 infants and children (mean age 16.1 months, mean body surface 0.43 m²) from a systemic artery (arterial) and the pulmonary artery (mixed venous). We also determined the pulmonary oxygen uptake and calculated the cardiac index (CI) using Fick's principle. In the analysis we compared the CI with the mixed venous oxygen saturation and with the quotient of the arterial oxygen content (C_aO₂) and the oxygen extraction . This quotient is equal to arterial oxygen delivery (DO₂) divided by the oxygen consumption (VO₂).Results Pearson's correlation coefficient was 0.77 when was compared to CI in a linear regression model. Assuming an inverse relationship between and CI the correlation was much better (r=0.90). However, the best estimation of CI provides the quotient .Conclusions correlates much better with CI than the , therefore CI could be better estimated based on . Furthermore provides good information about the oxygen supply situation of the body.     

Effects of breathing patterns on mechanically ventilated patients with chronic obstructive pulmonary disease and dynamic hyperinflation

Objective To examine the circulatory and respiratory effects of breathing pattern in patients with chronic obstructive pulmonary disease (COPD) and dynamic hyperinflation (DH) during controlled mechanical ventilation.Design Prospective, controlled, randomized, non-blinded study.Setting Respiratory intensive care unit of a university hospital.Patients Nine patients with acute respiratory failure and DH due to acute exacerbations of COPD.Interventions Keeping tidal volume and total breath duration (T_TOT) constant, patients were ventilated at six different values of expiratory time (T_E). T_E changes were randomly induced by alterations of constant inspiratory flow and/or end-inspiratory pause (EIP). Patients were studied at three levels of (0.93±0.08, 0.72±0.06 and 0.55±0.04 l/s, mean ±SE), with and without EIP (10% of T_TOT).Measurements and results Lung volumes, airflows, airways pressures, oxygenation indices and dead space were measured. Alveolar pressure and airway resistance (Rmin), as well as the additional resistance (R) due to viscoelastic pressure dissipation and time-constant inequalities, were estimated by rapid airway occlusion during inflation. In seven out of nine patients, right-heart catheterization was performed and hemodynamic parameters were obtained at each value of T_E. A significant decrease of intrinsic positive end-expiratory pressure (PEEPi), end-inspiratory static and mean (mPaw) airway pressures, end-expiratory lung volume above passive FRC (Vtrap), R and venous admixture and a significant increase of peak airway pressure, Rmin, stroke volume index and mixed venous PO₂ were observed when increased. At each , the addition of EIP significantly decreased iso-volume expiratory flows and and increased Vtrap and mPaw.Conclusions We conclude that in mechanically ventilated patients with COPD, the pattern of lung inflation and T_E alteration have a significant impact on respiratory system mechanics, gas exchange and hemodynamics. Addition of EIP in patients with COPD may be detrimental.     

Central mixed and splanchnic venous oxygen saturation monitoring

Central mixed venous oxygen saturation (S O₂) monitoring in critically ill patients to estimate adequacy of peripheral perfusion is gaining increasing popularity. However, a number of unexpected responses, one of which is marked depression of regional (splanchnic) venous oxygen saturation which may coexist with normal or high S O₂, makes interpretation pretation of this parameter difficult. The S O₂ and hepatic venous oxygen saturation levels in seven injured (postoperative) and 15 septic patients were measured. No substantial differences between central and hepatic venous oxygen saturation were noted in nonseptic patients, however, septic subjects exhibited a normal S O₂ of 70.5%±8.7% at a time when the hepatic venous saturation was 55.6%±14.4% which is a significant (p<0.05) reduction. This reduced oxygen saturation was noted to arise from an increased regional metabolic rate rather than reduced perfusion. Nevertheless, we conclude that a flow limited regional oxygen consumption may potentially exist despite the presence of a normal S O₂ in certain patient subgroups such as septic subjects. Therefore, a normal S O₂ should not be considered as sole criteria to insure optimal oxygen delivery in critically ill patients.     

Continuous intravascular monitoring of PO2 and PCO2. A comparativein vitro-in vivo study

Two electrodes placed at the tip of catheters forin vivo determinations of and respectively, were tested in dogs. Results were satisfactory when compared to a highly accurate reference method, correlation coefficients were close to 1 (P < 10^–9). Means of the differences were respectively –1.74 ± 1.14 torr for the probe (P < 0.01) and –1.62 ± 0.72 torr for the sensor (P < 0.0001). While no drift was detected in the electrode that of the was significant but negligible compared to the variability of measurements. Thus, for values between 20 and 85 torr, and values between 20 and 140 torr,in vivo monitoring is sufficiently reliable for clinical use.This study was supported by a grant-in-aid from I.N.S.E.R.M., C.N.R.S. and Paris VII University.     

Decreased critical mixed venous oxygen tension and critical oxygen transport during induced hypothermia in pigs

The effects of hypothermia on oxygen delivery and tolerance to hypoxia were studied in 8 normothermic (36.8°C) and 10 hypothermic (29.3°C) pigs that had been anesthetized and surgically implanted with instruments. Cardiac output ( t), o ₂ [oxygen consumption, or t × , where is arteriovenous oxygen content difference], arterial and mixed venous blood gas values, and lactate concentrations were measured as the animals were made progressively hypoxic. Under control, normoxic conditions, mixed venous oxygen tension ( ) was 41.4 ± 2.1 mm Hg (mean ± SE) in the normothermic animals and 26.1 ± 1.6 mm Hg in the hypothermic animals; these values are close to those predicted in our previous theoretical analysis. To study tolerance to hypoxia during hypothermia, critical and critical total oxygen transport (TOT = t × CaO₂, where CaO₂ is oxygen content of arterial blood) were determined by decreasing the inspired oxygen concentration (FiO₂) in steps and measuring the point where o ₂ and blood lactate levels becamePo ₂ or TOT dependent. Again as predicted, the critical was lower in the hypothermic animals (15.5 ± 1.0 mm Hg at 29.3°C compared with 22.0 ± 1.4 mm Hg at 36.8°C), but critical venous oxyhemoglobin saturation values were not statistically different at the two temperatures. Critical TOT was also decreased during hypothermia, as was the margin of reserve in both and TOT (the difference between the normoxic and the critical values).Supported by Grants HL 17731 and HL 07212 from the National Institutes of Health, and by grants from the California Lung Association and the Veterans Administration.The authors acknowledge the valuable technical assistance of Eric Merhoff and J. J. Wright.This work is a portion of: Willford DC. Oxygen transport and utilization during induced hypothermia, PhD Dissertation, University of California, San Diego, 1985. Some of this work was presented in preliminary form at meetings of the American Physiological Society in 1982, 1983, and 1985 [38–40], and at the 1985 symposium, Swine in Biomedical Research [2,41].     

Evaluation of methods for indirect calorimetry with a ventilated lung model

A combined lung and ventilator model was built, validated and used to test commercial systems for indirect calorimetry. It simulates O₂ uptake and CO₂ excretion under ventilator treatment conditions. In the model inspiratory gases are diluted with N₂ and CO₂ to give the desired expiratory concentrations. Minute volume, F_I O ₂, ventilatory pressure, and consequently RQ can be altered to simulate the adult clinical situation. A selected respiratory pattern is maintained by the lung model. Equipment for indirect calorimetry can then be connected to it and the results compared. Reference values are derived from measurements with a mass spectrometer and a Godart spirometer. Three commercially available instruments (Beckman MMC, Horizon MMC and Engström MC) were evaluated with this system. The limits of agreement with the reference values under different conditions (F₁ O ₂ 0.4–0.7, ventilatory pressure 0–50 cmH₂O) were determined. Differences as high as 15% from the true values of and were observed. The pattern of mechanical ventilation and the intrinsic properties of the analyzers in the equipment used for indirect calorimetry influence measurements to a significant extent.This publication includes part of the thesis of J. Zundel and preliminary data were presented at the Workshop Salzburg 1986: Methodische Fragen zur indirekten Kalorimetrie.This publication includes part of the thesis of J. Zundel and preliminary data were presented at the Workshop Salzburg 1986: Methodische Fragen zur indirekten Kalorimetrie.     

Effect of measurement errors on cardiac output calculated with O2 and modified CO2 Fick methods

We have investigated the effect of measurement errors on cardiac output, calculated via three different Fick methods. In method 1, the classic O₂ Fick equation is expressed in terms of oxygen uptake ( ), arterial pulse (Sao₂) and venous oximetry (Svo₂) saturations. The second method, a modified CO₂ Fick method, is obtained by replacing in method 1 with carbon dioxide production ( ) divided by the respiratory quotient. In method 3, cardiac output is expressed as divided by the product of the Sao₂-Svo₂ difference and a constant. This constant is determined from initial measurements of , Sao₂, Svo₂, and thermodilution cardiac output (Q_th). This determination of the constant results in equality of the initial cardiac output of method 3 with the simultaneously determined Q_th and, therefore, is similar to performing an autocalibration. For each of the three preceding Fick methods, we derive general expressions that explicitly show how measurement errors (random and systematic) in the Fick variables ( , , Sao₂, and Svo₂) propagate into errors in calculated cardiac output. The errors in theoretically calculated cardiac output decrease as the Sao₂-Svo₂ difference increases, except for the systematic error in method 3. The systematic error of method 3 is constant and depends only upon the accuracy of the initial Q_th. Analytic expressions for the sensitivity of calculated cardiac output to errors in individual Fick variables are also obtained. Using estimates from the literature for typical systematic and random measurement errors in the Fick variables, the resultant errors in cardiac output are numerically calculated. The effect of random measurement errors on errors in calculated cardiac output was comparable among the three methods. However, the systematic error was least with method 3. Total errors (random and systematic) were comparable among the three methods. Using these numerical measurement errors, we conclude that continuous cardiac output may be calculated with comparable accuracy with each of these methods.     

Immediate metabolic effects of different nutritional regimens in critically ill medical patients

Objective Metabolic effects of different caloric regimens were investigated in nonsurgical, medical patients with multipleorgan failure (MOF).Design Seven total parenteral nutrition (TPN) regimens were administered, differing in amount (14, 28, and 56 kcal/kg per day, i.e., hypo-, iso-, and hypercaloric nutrition, respectively) and distribution [carbohydrates (COH), amino acids (AA), long-chain and mediumchain triglycerides (LCT/MCT)] of calories. Each regimen was administered over 12 h. Metabolism was monitored by energy expenditure (EE), body temperature (BT), protein breakdown (PB), and blood glucose and serum lactate levels. Measurements were started within 2 days of MOF onset.Setting The study was conducted in a medical intensive care unit.Patients: Twenty patients with MOF on mechanical ventilation (mean Apache II score =26) were investigated.Measurements and results The mean values of the EE ( =31 kcal/kg per day), BT ( -38°C), PB ( =1.5 g/kg per day), and lactate ( =2.0 mmol/l) and glucose level ( =222 mg/dl) parameters were elevated. EE, BT, and lactate and glucose levels were significantly lower under hypocaloric nutrition than during iso- and hypercaloric nutrition (p<0.01). Differences in the metabilic effects of LCT and MCT were not significant. PB was significantly elevated under hypercaloric nutrition (p<0.01). Protein balance was positive under hypercaloric nutrition, and negative under iso- and hypocaloric nutrition.Conclusions In nonsurgical, medical patients neither hypercaloric nor isocaloric nutritional support prevented protein catabolism; in contrast, they enhanced the metabolic burden measured by EE, thermogenesis, urea production rate, and glucose and lactate levels. A hypocaloric regimen is therefore recommended for these patients during the early phase of MOF.