Sequential changes in the metabolic response in severely septic patients during the first 23 days after the onset of peritonitis

How much protein and energy are needed to equilibrate nitrogen and energy balances in ventilated critically ill children?

BACKGROUND & AIMS

Protein and energy requirements in critically ill children are currently based on insufficient data. Moreover, longitudinal measurements of both total urinary nitrogen (TUN) and resting energy expenditure (REE) are lacking. The aim of this study was to investigate how much protein and energy are needed to equilibrate nitrogen and energy balances in ventilated critically ill children on the basis of daily measurements of TUN, REE and protein and energy intakes. Comparisons were made with the guidelines of the American Society for Parenteral and Enteral Nutrition and the Dietary Reference Intakes.

METHODS

Children with an expected duration of mechanical ventilation ≥72 h were prospectively recruited. TUN was measured by chemiluminescence, and REE was measured by indirect calorimetry. Generalised linear models for longitudinal data were used to study the relation between protein intake and nitrogen balance and to calculate the minimum intake of protein needed to achieve nitrogen equilibrium. A similar approach was used for energy. Results were compared to the recommended values.

RESULTS

Based on 402 measurements performed in 74 children (median age: 21 months), the mean TUN was high at 0.20 (95% CI: 0.20, 0.22) g/kg/d and the REE was 55 (95% CI: 54, 57) kcal/kg/d. Nitrogen and energy balances were achieved with 1.5 (95% CI: 1.4, 1.6) g/kg/d of protein and 58 (95% CI: 53, 63) kcal/kg/d for the entire group, but there were differences among children of different ages. Children required more protein and less energy than the Dietary Reference Intakes.

CONCLUSIONS

In critically ill children, TUN was elevated and REE was reduced during the entire period of mechanical ventilation. Minimum intakes of 1.5 g/kg/d of protein and 58 kcal/kg/d can equilibrate nitrogen and energy balances in children up to 4 years old. Older children require more protein.

Validation Study of Energy Requirements in Critically Ill, Obese Cancer Patients

BACKGROUND

Current guidelines from the American Society for Parenteral and Enteral Nutrition and the Society of Critical Care Medicine (ASPEN/SCCM) regarding caloric requirements and the provision of nutrition support in critically ill, obese adults may not be suitable for similar patients with cancer. We sought to determine whether the current guidelines accurately estimate the energy requirements, as measured by indirect calorimetry (IC), of critically ill, obese cancer patients.

MATERIALS AND METHODS

This was a retrospective validation study of critically ill, obese cancer patients from March 1, 2007, to July 31, 2010. All patients ≥18 years of age with a body mass index (BMI) ≥30 kg/m(2) who underwent IC were included. We compared the measured energy expenditure (MEE) against the upper limit of the recommended guideline (25 kcal/kg of ideal body weight [IBW]) and MEE between medical and surgical patients in the intensive care unit.

RESULTS

Thirty-three patients were included in this study. Mean MEE (28.7 ± 5.2 kcal/kg IBW) was significantly higher than 25 kcal/kg IBW (P < .001), and 78% of patients had nutrition requirements greater than the current guideline recommendations. No significant differences in MEE between medical and surgical patients in the ICU were observed.

CONCLUSIONS

Critically ill, obese cancer patients require more calories than the current guidelines recommend, likely due to malignancy-associated metabolic variations. Our results demonstrate the need for IC studies to determine the energy requirements in these patients and for reassessment of the current recommendations.

Abandon the mouse research ship? Not just yet!

Many preclinical studies in critical care medicine and related disciplines rely on hypothesis-driven research in mice. The underlying premise posits that mice sufficiently emulate numerous pathophysiologic alterations produced by trauma/sepsis and can serve as an experimental platform for answering clinically relevant questions. Recently, the lay press severely criticized the translational relevance of mouse models in critical care medicine. A series of provocative editorials were elicited by a highly publicized research report in the Proceedings of the National Academy of Sciences (PNAS; February 2013), which identified an unrecognized gene expression profile mismatch between human and murine leukocytes following burn/trauma/endotoxemia. Based on their data, the authors concluded that mouse models of trauma/inflammation are unsuitable for studying corresponding human conditions. We believe this conclusion was not justified. In conjunction with resulting negative commentary in the popular press, it can seriously jeopardize future basic research in critical care medicine. We will address some limitations of that PNAS report to provide a framework for discussing its conclusions and attempt to present a balanced summary of strengths/weaknesses of use of mouse models. While many investigators agree that animal research is a central component for improved patient outcomes, it is important to acknowledge known limitations in clinical translation from mouse to man. The scientific community is responsible to discuss valid limitations without overinterpretation. Hopefully, a balanced view of the strengths/weaknesses of using animals for trauma/endotoxemia/critical care research will not result in hasty discount of the clear need for using animals to advance treatment of critically ill patients.

Exploitation of diagnostic computed tomography scans to assess the impact of nutrition support on body composition changes in respiratory failure patients

BACKGROUND

Assessment of nutritional status in intensive care unit (ICU) patients is limited. Computed tomography (CT) scans that include the first to fifth lumbar region completed for diagnostic purposes measures fat and lean body mass (LBM) depots and are frequently done in ICU populations and can be used to quantify fat and LBM depots. The purpose of this study was to assess if these scans could measure change in skeletal muscle (SKT), visceral adipose (VAT), and intermuscular adipose (IMAT) tissue and to examine the association between the amount of energy and protein received and changes in these depots.

METHODS

Cross-sectional area of SKT, VAT, and IMAT from CT scans at the third lumbar region was quantified at 2 time points (CT1 and CT2). Change scores between CT1 and CT2 for each of these depots and the percentage of estimated energy/protein needs received were determined in 33 adults that with acute respiratory failure. Descriptive statistics and multiple regression was used to evaluate the influence of baseline characteristics and the percentage energy/protein needs received between CT1 and CT2 on percentage change/day between CT1 and CT2 on SKM, IMAT, and VAT.

RESULTS

Participants were on average (SD) 59.7 (16) years old, received 41% of energy and 57% of protein needs. The average time between CT1 and CT2 was 10 (5) days. SKM declined 0.49%/day (men P = .07, women P = .09) and percentage of energy needs received reduced loss (β = 0.024, P = .03). No change in VAT or IMAT occurred.

CONCLUSIONS

CT scans can be exploited to assess change in body composition in ICU patients and may assist in detecting the causal link between nutritional support and outcomes in future clinical trials.

Anesthetic management for patients with perforation peritonitis

Perforation peritonitis is a common surgical emergency. Anesthesia in patients with perforation peritonitis can be challenging. Delayed presentations, old age, hemodynamic instability, presence of sepsis and organ dysfunction are some of the predictors of poor outcome in such patients. Pre-operative optimization can reduce intraoperative and post-operative morbidity and mortality, but surgery should not be unnecessarily delayed. Intensive care in critical care settings may be essential.

Energy estimation and measurement in critically ill patients

The estimation of caloric needs of critically ill patients is usually based on energy expenditure (EE), while current recommendations for caloric intake most often rely on a fixed amount of calories. In fact, during the early phase of critical illness, caloric needs are probably lower than EE, as a substantial proportion of EE is covered by the non-inhibitable endogenous glucose production. Hence, the risk of overfeeding is higher during the early phase than the late phase, while the risk of underfeeding is higher during the late phase of critical illness. Therefore, an accurate measurement of EE can be helpful to prevent early overfeeding and late underfeeding. Available techniques to assess EE include predictive equations, calorimetry, and doubly labeled water, the reference method. The available predictive equations are often inaccurate, while indirect calorimetry is difficult to perform for several reasons, including a shortage of reliable devices and technical limitations. In this review, the authors intend to discuss the different techniques and the influence of the method used on the interpretation of the results of clinical studies.

Insulin-like growth factor-I (IGF-I) and clinical nutrition

IGF-I (insulin-like growth factor-I) is a peptide hormone, produced predominantly by the liver in response to pituitary GH (growth hormone), which is involved in a wide variety of physiological processes. It acts in an endocrine, paracrine and autocrine manner to promote growth. The production of IGF-I signals the availability of nutrients needed for its anabolic actions. Recently, there has been growing interest in its role in health and disease. IGF-I has long been known to be regulated by nutrition and dysregulated in states of under- and over-nutrition, its serum concentrations falling in malnutrition and responding promptly to refeeding. This has led to interest in its utility as a nutritional biomarker. A considerable evidence base supports utility for measurement of IGF-I in nutritional contexts. Its concentration may be valuable in providing information on nutritional status, prognosis and in monitoring nutritional support. However, it is insufficiently specific for use as a screening test for under nutrition as its serum concentration is influenced by many factors other than nutritional status, notably the APR (acute-phase response) and endocrine conditions. Concentrations should be interpreted along with clinical findings and the results of other investigations such as CRP (C-reactive protein). More recently, there has been interest in free IGF-I which holds promise as a nutritional marker. The present review covers nutritional regulation of IGF-I and its dysregulation in disease, then goes on to review recent studies supporting its utility as a nutritional marker in clinical contexts. Although not currently recommended by clinical guidelines, it is likely that, in time, measurement of IGF-I will become a routine part of nutritional assessment in a number of these contexts.

Thyroid hormone concentrations in foals affected by perinatal asphyxia syndrome

The hypothalamus-pituitary-thyroid axis has specific functions, mostly related to metabolic activities, cell differentiation, and development. To the authors' knowledge, there are no studies about thyroid hormone (TH) concentrations in foals affected by perinatal asphyxia syndrome (PAS). Hence, the aims of the study are (1) to evaluate plasma TH concentrations (T3 and T4) in healthy foals during the first 7 days of life; (2) to evaluate plasma TH concentration (T3 and T4) in critically ill foals affected by PAS during the first 7 days of hospitalization; and (3) to compare TH concentrations between surviving and nonsurviving critically ill foals. Forty-five Standardbred foals were enrolled in this prospective observational study: 21 healthy foals (group 1) and 24 foals affected by PAS (group 2). Jugular blood samples were collected within 10 minutes from birth/admission and every 24 hours for 7 days (t0-t7). TH concentrations were analyzed by RIA. In both groups, T3 concentration was significantly lower at t4, t5, t6, and t7 compared with t1 (P < 0.05), and T4 concentration was significantly higher at birth than at all other time points (P < 0.01). No differences were found in TH concentrations at admission between surviving (n = 20) and nonsurviving (n = 4) foals. Statistical comparison between healthy and PAS foals divided into age groups showed significantly lower TH concentrations at t0 in PAS foals <12 hours old at admission (P < 0.01). In conclusion, PAS may cause lower T3 and T4 concentrations in affected foals than in age-matched healthy foals, as reported for other systemic illnesses, such as sepsis and prematurity. TH concentrations showed no prognostic value, which maybe due to the small number of nonsurviving foals in this study. Further studies are needed to find out if thyroid replacement therapy could be useful in the treatment of critically ill foals affected by PAS.

Regulation of muscle protein synthesis and the effects of catabolic states

Protein synthesis and degradation are dynamically regulated processes that act in concert to control the accretion or loss of muscle mass. The present article focuses on the mechanisms involved in the impairment of protein synthesis that are associated with skeletal muscle atrophy. The vast majority of mechanisms known to regulate protein synthesis involve modulation of the initiation phase of mRNA translation, which comprises a series of reactions that result in the binding of initiator methionyl-tRNAi and mRNA to the 40S ribosomal subunit. The function of the proteins involved in both events has been shown to be repressed under atrophic conditions such as sepsis, cachexia, chronic kidney disease, sarcopenia, and disuse atrophy. The basis for the inhibition of protein synthesis under such conditions is likely to be multifactorial and includes insulin/insulin-like growth factor 1 resistance, pro-inflammatory cytokine expression, malnutrition, corticosteroids, and/or physical inactivity. The present article provides an overview of the existing literature regarding mechanisms and signaling pathways involved in the regulation of mRNA translation as they apply to skeletal muscle wasting, as well as the efficacy of potential clinical interventions such as nutrition and exercise in the maintenance of skeletal muscle protein synthesis under atrophic conditions. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.

Disease-specific nutrition therapy: one size does not fit all

INTRODUCTION

The delivery of adequate nutrition is an integral part of the care of the critically ill surgical patient, and the provision of nutrition may have a greater impact on outcome than many other therapies commonly employed in the treatment of certain disease states.

METHODS

A review of the existing literature was performed to summarize the evidence for utilizing disease-specific nutrition in critically ill surgical patients.

RESULTS

Enteral nutrition, unless specifically contraindicated, is always preferable to parenteral nutrition. Methodological heterogeneity and conflicting results plague research in immunonutrition, and routine use is not currently recommended in critically ill patients.

CONCLUSION

There is currently insufficient evidence to recommend the routine initial use of most disease-specific formulas, as most patients with the disease in question will tolerate standard enteral formulas. However, the clinician should closely monitor for signs of intolerance and utilize disease-specific formulas when appropriate.

Postoperative Respiratory Muscle Dysfunction

Postoperative pulmonary complications are responsible for significant increases in hospital cost as well as patient morbidity and mortality; respiratory muscle dysfunction represents a contributing factor. Upper airway dilator muscles functionally resist the upper airway collapsing forces created by the respiratory pump muscles. Standard perioperative medications (anesthetics, sedatives, opioids, and neuromuscular blocking agents), interventions (patient positioning, mechanical ventilation, and surgical trauma), and diseases (lung hyperinflation, obesity, and obstructive sleep apnea) have differential effects on the respiratory muscle subgroups. These effects on the upper airway dilators and respiratory pump muscles impair their coordination and function and can result in respiratory failure. Perioperative management strategies can help decrease the incidence of postoperative respiratory muscle dysfunction. Such strategies include minimally invasive procedures rather than open surgery, early and optimal mobilizing of respiratory muscles while on mechanical ventilation, judicious use of respiratory depressant anesthetics and neuromuscular blocking agents, and noninvasive ventilation when possible.

Endocrine, metabolic, and morphologic alterations of adipose tissue during critical illness

OBJECTIVE

Observational studies report lower mortality in obese than in lean critically ill patients, an association referred to as the "obesity paradox." This may suggest a possible protective role for adipose tissue during severe illness.

DATA SOURCES

Relevant publications were identified based on searches in PubMed and on secondary searches of their bibliographies.

DATA SYNTHESIS

The endocrine functions of adipose tissue might play a role in the adaptation to critical illness. In the acute phase of illness, the anti-inflammatory adiponectin is reduced, whereas proinflammatory cytokine expression in adipose tissue is up-regulated. In the prolonged phase of critical illness, both adiponectin and anti-inflammatory cytokine production are increasing. Studies on the proinflammatory adipokine leptin during critical illness are inconsistent, possibly due to confounders such as gender, body mass index, and feeding. Morphologically, adipose tissue of critically ill patients reveals an increased number of newly differentiated, smaller adipocytes. Accentuated macrophage accumulation showing a phenotypic switch to M2-type suggests an adaptive response to the microenvironment of severe illness. Functionally, adipose tissue of critically ill patients develops an increased ability to store glucose and triglycerides.

CONCLUSIONS

Endocrine, metabolic, and morphologic properties of adipose tissue change during critical illness. These alterations may suggest a possible adaptive, protective role in optimizing chances of survival. More research is needed to understand the exact role of adipose tissue in lean vs. obese critically ill patients, in order to understand how illness-associated alterations contribute to the obesity paradox.

Combining creatinine and volume kinetics identifies missed cases of acute kidney injury following cardiac arrest

Introduction

Fluid resuscitation in the critically ill often results in a positive fluid balance, potentially diluting the serum creatinine concentration and delaying diagnosis of acute kidney injury (AKI).

Methods

Dilution during AKI was quantified by combining creatinine and volume kinetics to account for fluid type, and rates of fluid infusion and urine output. The model was refined using simulated patients receiving crystalloids or colloids under four glomerular filtration rate (GFR) change scenarios and then applied to a cohort of critically ill patients following cardiac arrest.

Results

The creatinine concentration decreased during six hours of fluid infusion at 1 litre-per-hour in simulated patients, irrespective of fluid type or extent of change in GFR (from 0% to 67% reduction). This delayed diagnosis of AKI by 2 to 9 hours. Crystalloids reduced creatinine concentration by 11 to 19% whereas colloids reduced concentration by 36 to 43%. The greatest reduction was at the end of the infusion period. Fluid dilution alone could not explain the rapid reduction of plasma creatinine concentration observed in 39 of 49 patients after cardiac arrest. Additional loss of creatinine production could account for those changes. AKI was suggested in six patients demonstrating little change in creatinine, since a 52 ± 13% reduction in GFR was required after accounting for fluid dilution and reduced creatinine production. Increased injury biomarkers within a few hours of cardiac arrest, including urinary cystatin C and plasma and urinary Neutrophil-Gelatinase-Associated-Lipocalin (biomarker-positive, creatinine-negative patients) also indicated AKI in these patients.

Conclusions

Creatinine and volume kinetics combined to quantify GFR loss, even in the absence of an increase in creatinine. The model improved disease severity estimation, and demonstrated that diagnostic delays due to dilution are minimally affected by fluid type. Creatinine sampling should be delayed at least one hour following a large fluid bolus to avoid dilution. Unchanged plasma creatinine post cardiac arrest signifies renal injury and loss of function.

Trial registration

Australian and New Zealand Clinical Trials Registry ACTRN12610001012066.

The insulin-like growth factor system and nutritional assessment

Over recent years there has been considerable interest in the role of the insulin-like growth factor (IGF) system in health and disease. It has long been known to be dysregulated in states of under- and overnutrition, serum IGF-I levels falling in malnourished patients and responding promptly to nutritional support. More recently, other proteins in this system have been observed to be dysregulated in both malnutrition and obesity. Currently no biochemical marker is sufficiently specific for use in screening for malnutrition, but levels may be valuable in providing information on nutritional status and in monitoring of nutritional support. All have limitations as nutritional markers in that their serum levels are influenced by factors other than nutritional status, most importantly the acute phase response (APR). Levels should be interpreted along with clinical findings and the results of other investigations such as C-reactive protein (CRP). This paper reviews data supporting the use of proteins of the IGF system as nutritional markers.

Motility disorders of the upper gastrointestinal tract in the intensive care unit: pathophysiology and contemporary management

Upper gastrointestinal (GI) dysmotility, an entity commonly found in the intensive care unit setting, can lead to insufficient nutrient intake while increasing the risk of infection and mortality. Further, overcoming the altered motility with early enteral feeding is associated with a reduced incidence of infectious complications in intensive care unit patients. Upper GI dysmotility in critical care patients is a common occurrence, and there are many causes for this problem, which affects a very heterogenous population with a multitude of underlying medical abnormalities. Therefore, it is of utmost importance to identify this widespread problem and subsequently institute a proper therapy as rapidly as possible. Prokinetic pharmacotherapies are currently the mainstay for the management of disordered upper GI motility. Future therapies, aimed at the underlying pathophysiology of this complex problem, are under investigation. These aim is to reduce the side effects of the currently available options, while improving on nutrition delivery in the critically ill. This review discusses the pathophysiology, clinical manifestations, diagnosis, and treatment of upper GI motility disturbances in the critically ill.

Shock - A reappraisal: The holistic approach

Shock as reaction to life-threatening condition needs to be reclassified in a timely and more scientific synopsis. It is not possible or beneficial any longer to avoid a holistic approach in critical illness. Semantics of critical illness has often been unfriendly in the literature and a simplification with the elimination of conceptual pleonasms and misnomers under the exclusive light of physiology and physiopathology would be advantageous. Speaking one language to describe the same phenomenon worldwide is essential for understanding; moreover, it increases focus on characterization and significance of the phenomena.

Body composition: why, when and for who?

Body composition reflects nutritional intakes, losses and needs over time. Undernutrition, i.e. fat-free mass (FFM) loss, is associated with decreased survival, worse clinical outcome and quality of life, as well as increased therapy toxicity in cancer patients. In numerous clinical situations, such as sarcopenic obesity and chronic diseases, the measurement of body composition with available methods, such as dual-X ray absorptiometry, computerized tomography and bioelectrical impedance analysis, quantifies the loss of FFM, whereas body weight loss and body mass index only inconstantly reflect FFM loss. The measurement of body composition allows documenting the efficiency of nutrition support, tailoring the choice of disease-specific and nutritional therapies and evaluating their efficacy and putative toxicity. Easy-to-use body composition methods integrated to the routine of care allow sequential measurements for an initial nutritional assessment and objective patients follow-up. By allowing an earlier and objective management of undernutrition, body composition assessment could contribute to reduce undernutrition-induced morbidity, worsening of quality of life, and global health care costs by a timely nutrition intervention.

Effect of transcutaneous electrical muscle stimulation on muscle volume in patients with septic shock

OBJECTIVE

Intensive care unit admission is associated with muscle wasting and impaired physical function. We investigated the effect of early transcutaneous electrical muscle stimulation on quadriceps muscle volume in patients with septic shock.

DESIGN

Randomized interventional study using a single-legged exercise design with the contralateral leg serving as a paired control.

SETTING

A mixed 18-bed intensive care unit at a tertiary care university hospital.

PATIENTS

Eight adult male intensive care unit patients with septic shock included within 72 hrs of diagnosis.

INTERVENTIONS

After randomization of the quadriceps muscles, transcutaneous electrical muscle stimulation was applied on the intervention side for 7 consecutive days and for 60 mins per day. All patients underwent computed tomographic scans of both thighs immediately before and after the 7-day treatment period. The quadriceps muscle was manually delineated on the computed tomography slices, and muscle volumes were calculated after three-dimensional reconstruction.

MEASUREMENTS AND MAIN RESULTS

Median age and Acute Physiology and Chronic Health Evaluation II score were 67 years (interquartile range, 64-72 years) and 25 (interquartile range, 20-29), respectively. During the 7-day study period, the volume of the quadriceps muscle on the control thigh decreased by 16% (4-21%, p=.03) corresponding to a rate of 2.3% per day. The volume of the stimulated muscle decreased by 20% (3-25%, p=.04) corresponding to a rate of 2.9% per day (p=.12 for the difference in decrease). There was no difference in muscle volume between the stimulated and nonstimulated thigh at baseline (p=.10) or at day 7 (p=.12). The charge delivered to the muscle tissue per training session (0.82 [0.66-1.18] coulomb) correlated with the maximum sequential organ failure assessment score.

CONCLUSIONS

We observed a marked decrease in quadriceps volume within the first week of intensive care for septic shock. This loss of muscle mass was unaffected by transcutaneous electrical muscle stimulation applied for 60 mins per day for 7 days.

Preadmission beta-blocker use and 30-day mortality among patients in intensive care: a cohort study

Introduction

Beta-blockers have cardioprotective, metabolic and immunomodulating effects that may be beneficial to patients in intensive care. We examined the association between preadmission beta-blocker use and 30-day mortality following intensive care.

Methods

We identified 8,087 patients over age 45 admitted to one of three multidisciplinary intensive care units (ICUs) between 1999 and 2005. Data on the use of beta-blockers and medications, diagnosis, comorbidities, surgery, markers of socioeconomic status, laboratory tests upon ICU admission, and complete follow-up for mortality were obtained from medical databases. We computed probability of death within 30 days following ICU admission for beta-blocker users and non-users, and the odds ratio (OR) of death as a measure of relative risk using conditional logistic regression and also did a propensity score-matched analysis.

Results

Inclusion of all 8,087 ICU patients in a logistic regression analysis yielded an adjusted OR of 0.82 (95% confidence interval (CI): 0.71 to 0.94) for beta-blocker users compared with non-users. In the propensity score-matched analysis we matched all 1,556 beta-blocker users (19.2% of the entire cohort) with 1,556 non-users; the 30-day mortality was 25.7% among beta-blocker users and 31.4% among non-users (OR 0.74 (95% CI: 0.63 to 0.87)]. The OR was 0.69 (95% CI: 0.54 to 0.88) for surgical ICU patients and 0.71 (95% CI: 0.51 to 0.98) for medical ICU patients. The OR was 0.99 (95% CI: 0.67 to 1.47) among users of non-selective beta-blockers, and 0.70 (95% CI: 0.58 to 0.83) among users of cardioselective beta-blockers.

Conclusions

Preadmission beta-blocker use is associated with reduced mortality following ICU admission.

Acute kidney injury in older adults

Aging kidneys undergo structural and functional changes that decrease autoregulatory capacity and increase susceptibility to acute injury. Acute kidney injury associates with duration and location of hospitalization, mortality risk, progression to chronic kidney disease, and functional status in daily living. Definition and diagnosis of acute kidney injury are based on changes in creatinine, which is an inadequate marker and might identify patients when it is too late. The incidence of acute kidney injury is rising and increases with advancing age, yet clinical studies have been slow to address geriatric issues or the heterogeneity in etiologies, outcomes, or patient preferences among the elderly. Here we examine some of the current literature, identify knowledge gaps, and suggest potential research questions regarding acute kidney injury in older adults. Answering these questions will facilitate the integration of geriatric issues into future mechanistic and clinical studies that affect management and care of acute kidney injury.

Interstitium: the next diagnostic and therapeutic platform in critical illness

BACKGROUND

For decades we have been testing blood either ex vivo or else placing monitors directly in the bloodstream to "see" what might be going on in tissues. In the last 20 yrs, conceptual and practical advances in interstitial monitoring have begun to challenge traditional approaches. In this review we explore how interstitial monitoring might be used as a platform for future diagnostics and therapy in critical illness.

RESULTS

From a diagnostic perspective, interstitial analysis has been instructive about the pathophysiology of critical illness. Valuable insights have been gained into the pathophysiology of critical illness. To this end, examples from the areas of interstitial oxygenation and acid base, endocrine pathophysiology, and head injury monitoring have been used. From a therapeutic perspective, the main focus has been on antibiotic therapy and an improved understanding of pharmacokinetics and pharmacodynamics in critical illness.

CONCLUSIONS

Monitoring of the interstitium is feasible and can be achieved through minimally invasive techniques. It has improved the understanding of the pathophysiology of critical illness, holds potential in the diagnosis and management of sepsis, may allow early prediction of organ deterioration, and finally offers the possibility of reduction of blood testing and minimizing blood loss. While all of these hold promise, randomized trials will need to be conducted based on interstitial end points rather than plasma end points. This will pave the way for a more rational approach to the therapy of critically ill patients.

Nutrition assessment: the reproducibility of subjective global assessment in patients requiring mechanical ventilation

Background/Objective

The detection of malnutrition in the intensive care unit (ICU) is critical to appropriately address its contribution on outcomes. The primary objective of this investigation was to determine if nutritional status could be reliably classified using Subjective Global Assessment (SGA) in mechanically ventilated (MV) patients.

Subjects/Methods

Fifty-seven patients requiring MV greater than 48 hours in a university-affiliated medical ICU were evaluated in this cross-sectional study over a 3 month period. Nutritional status was categorized independently by two Registered Dietitians using SGA. Frequencies, means (± standard deviations), Chi square and T tests were used to describe the population characteristics; agreement between raters was evaluated using the κ statistic.

Results

On admission, the average patient was 50.4 (± 14.2) years of age, overweight (body mass index: 29.0 ± 9.2), had an APACHE II score of 24 (± 10) and respiratory failure. Fifty percent (n=29) of patients were categorized as malnourished. Agreement between raters was 95% prior to consensus, reflecting near perfect agreement (κ =0.90) and excellent reliability. Patients categorized as malnourished were more often admitted to the hospital floor prior to the ICU (n=32; 56%), reported decreased dietary intake (69% vs. 46%, p=0.02) and exhibited signs of muscle wasting (45% vs. 7%, p<0.001, respectively) and fat loss (52% vs. 7%, p<0.001, respectively) on physical exam when compared to normally nourished individuals.

Conclusions

SGA can serve as a reliable nutrition assessment technique for detecting malnutrition in patients requiring MV. Its routine use should be incorporated into future studies and clinical practice.

A meta-analysis of randomised controlled trials of intravenous fluid therapy in major elective open abdominal surgery: getting the balance right

The terminology used for describing intervention groups in randomised controlled trials (RCT) on the effect of intravenous fluid on outcome in abdominal surgery has been imprecise, and the lack of standardised definitions of the terms 'standard', 'restricted' and 'liberal' has led to some confusion and difficulty in interpreting the literature. The aims of this paper were to clarify these definitions and to use them to perform a meta-analysis of nine RCT on primarily crystalloid-based peri-operative intravenous fluid therapy in 801 patients undergoing elective open abdominal surgery. Patients who received more or less fluids than those who received a 'balanced' amount were considered to be in a state of 'fluid imbalance'. When 'restricted' fluid regimens were compared with 'standard or liberal' fluid regimens, there was no difference in post-operative complication rates (risk ratio 0.83 (95% CI 0.49, 1.39, P = 0.47) [corrected] or length of hospital stay (weighted mean difference (WMD) - 1.77 (95% CI - 4.36, 0.81) d, P = 0.18). However, when the fluid regimens were reclassified and patients were grouped into those who were managed in a state of fluid 'balance' or 'imbalance', the former group had significantly fewer complications (risk ratio 0·59 (95% CI 0·44, 0·81), P=0·0008) and a shorter length of stay (WMD -3·44 (95% CI -6·33, -0·54) d, P=0·02) than the latter. Using imprecise terminology, there was no apparent difference between the effects of fluid-restricted and standard or liberal fluid regimens on outcome in patients undergoing elective open abdominal surgery. However, patients managed in a state of fluid balance fared better than those managed in a state of fluid imbalance.

Alterations in adipose tissue during critical illness: An adaptive and protective response?

RATIONALE

Critical illness is characterized by lean tissue wasting, whereas adipose tissue is preserved. Overweight and obese critically ill patients may have a lower risk of death than lean patients, suggestive of a protective role for adipose tissue during illness.

OBJECTIVES

To investigate whether adipose tissue could protectively respond to critical illness by storing potentially toxic metabolites, such as excess circulating glucose and triglycerides.

METHODS

We studied adipose tissue morphology and metabolic activity markers in postmortem biopsies of 61 critically ill patients and 20 matched control subjects. Adipose morphology was also studied in in vivo biopsies of 27 patients and in a rabbit model of critical illness (n = 22).

MEASUREMENTS AND MAIN RESULTS

Adipose tissue from critically ill patients revealed a higher number and a smaller size of adipocytes and increased preadipocyte marker levels as compared with control subjects. Virtually all adipose biopsies from critically ill patients displayed positive macrophage staining. The animal model demonstrated similar changes. Glucose transporter levels and glucose content were increased. Glucokinase expression was up-regulated, whereas glycogen and glucose-6-phosphate levels were low. Acetyl CoA carboxylase protein and fatty acid synthase activity were increased. Hormone-sensitive lipase activity was not altered, whereas lipoprotein lipase activity was increased. A substantially increased AMP-activated protein kinase activity may play a crucial role.

CONCLUSIONS

Postmortem adipose tissue biopsies from critically ill patients displayed a larger number of small adipocytes in response to critical illness, revealing an increased ability to take up circulating glucose and triglycerides. Similar morphologic changes were present in vivo. Such changes may render adipose tissue biologically active as a functional storage depot for potentially toxic metabolites, thereby contributing to survival.

Skeletal muscle loss: cachexia, sarcopenia, and inactivity

Loss of skeletal muscle mass occurs during aging (sarcopenia), disease (cachexia), or inactivity (atrophy). This article contrasts and compares the metabolic causes of loss of muscle resulting from these conditions. An understanding of the underlying causes of muscle loss is critical for the development of strategies and therapies to preserve muscle mass and function. Loss of skeletal muscle protein results from an imbalance between the rate of muscle protein synthesis and degradation. Cachexia, sarcopenia, and atrophy due to inactivity are characterized by a loss of muscle mass. Each of these conditions results in a metabolic adaptation of increased protein degradation (cachexia), decreased rate of muscle protein synthesis (inactivity), or an alteration in both (sarcopenia). The clinical consequences of bedrest may mimic those of cachexia, including rapid loss of muscle, insulin resistance, and weakness. Prophylaxis against bedrest-induced atrophy includes nutrition support with an emphasis on high-quality protein. Nutritional supplementation alone may not prevent muscle loss secondary to cachexia, but, in combination with the use of an anabolic agent, it may slow or prevent muscle loss.

Energy expenditure and energy intake - Guidelines on Parenteral Nutrition, Chapter 3

The energy expenditure (24h total energy expenditure, TEE) of a healthy individual or a patient is a vital reference point for nutritional therapy to maintain body mass. TEE is usually determined by measuring resting energy expenditure (REE) by indirect calorimetry or by estimation with the help of formulae like the formula of Harris and Benedict with an accuracy of +/-20%. Further components of TEE (PAL, DIT) are estimated afterwards. TEE in intensive care patients is generally only 0-7% higher than REE, due to a low PAL and lower DIT. While diseases, like particularly sepsis, trauma and burns, cause a clinically relevant increase in REE between 40-80%, in many diseases, TEE is not markedly different from REE. A standard formula should not be used in critically ill patients, since energy expenditure changes depending on the course and the severity of disease. A clinical deterioration due to shock, severe sepsis or septic shock may lead to a drop of REE to a level only slightly (20%) above the normal REE of a healthy subject. Predominantly immobile patients should receive an energy intake between 1.0-1.2 times the determined REE, while immobile malnourished patients should receive a stepwise increased intake of 1.1-1.3 times the REE over a longer period. Critically ill patients in the acute stage of disease should be supplied equal or lower to the current TEE, energy intake should be increased stepwise up to 1.2 times (or up to 1.5 times in malnourished patients) thereafter.

Increased inflammation, impaired bacterial clearance, and metabolic disruption after gram-negative sepsis in Mkp-1-deficient mice

MAPKs are crucial for TNF-alpha and IL-6 production by innate immune cells in response to TLR ligands. MAPK phosphatase 1 (Mkp-1) deactivates p38 and JNK, abrogating the inflammatory response. We have previously demonstrated that Mkp-1(-/-) mice exhibit exacerbated inflammatory cytokine production and increased mortality in response to challenge with LPS and heat-killed Staphylococcus aureus. However, the function of Mkp-1 in host defense during live Gram-negative bacterial infection remains unclear. We challenged Mkp-1(+/+) and Mkp-1(-/-) mice with live Escherichia coli i.v. to examine the effects of Mkp-1 deficiency on animal survival, bacterial clearance, metabolic activity, and cytokine production. We found that Mkp-1 deficiency predisposed animals to accelerated mortality and was associated with more robust production of TNF-alpha, IL-6 and IL-10, greater bacterial burden, altered cyclooxygenase-2 and iNOS expression, and substantial changes in the mobilization of energy stores. Likewise, knockout of Mkp-1 also sensitized mice to sepsis caused by cecal ligation and puncture. IL-10 inhibition by neutralizing Ab or genetic deletion alleviated increased bacterial burden. Treatment with the bactericidal antibiotic gentamicin, given 3 h after Escherichia coli infection, protected Mkp-1(+/+) mice from septic shock but had no effect on Mkp-1(-/-) mice. Thus, during Gram-negative bacterial sepsis Mkp-1 not only plays a critical role in the regulation of cytokine production but also orchestrates the bactericidal activities of the innate immune system and controls the metabolic response to stress.

Electrical muscle stimulation preserves the muscle mass of critically ill patients: a randomized study

Introduction

Critically ill patients are characterized by increased loss of muscle mass, partially attributed to sepsis and multiple organ failure, as well as immobilization. Recent studies have shown that electrical muscle stimulation (EMS) may be an alternative to active exercise in chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) patients with myopathy. The aim of our study was to investigate the EMS effects on muscle mass preservation of critically ill patients with the use of ultrasonography (US).

Methods

Forty-nine critically ill patients (age: 59 ± 21 years) with an APACHE II admission score ≥13 were randomly assigned after stratification upon admission to receive daily EMS sessions of both lower extremities (EMS-group) or to the control group (control group). Muscle mass was evaluated with US, by measuring the cross sectional diameter (CSD) of the vastus intermedius and the rectus femoris of the quadriceps muscle.

Results

Twenty-six patients were finally evaluated. Right rectus femoris and right vastus intermedius CSD decreased in both groups (EMS group: from 1.42 ± 0.48 to 1.31 ± 0.45 cm, P = 0.001 control group: from 1.59 ± 0.53 to 1.37 ± 0.5 cm, P = 0.002; EMS group: from 0.91 ± 0.39 to 0.81 ± 0.38 cm, P = 0.001 control group: from 1.40 ± 0.64 to 1.11 ± 0.56 cm, P = 0.004, respectively). However, the CSD of the right rectus femoris decreased significantly less in the EMS group (-0.11 ± 0.06 cm, -8 ± 3.9%) as compared to the control group (-0.21 ± 0.10 cm, -13.9 ± 6.4%; P < 0.05) and the CSD of the right vastus intermedius decreased significantly less in the EMS group (-0.10 ± 0.05 cm, -12.5 ± 7.4%) as compared to the control group (-0.29 ± 0.28 cm, -21.5 ± 15.3%; P < 0.05).

Conclusions

EMS is well tolerated and seems to preserve the muscle mass of critically ill patients. The potential use of EMS as a preventive and rehabilitation tool in ICU patients with polyneuromyopathy needs to be further investigated.

Trial Registration

clinicaltrials.gov: NCT00882830

Quantification of lean and fat tissue repletion following critical illness: a case report

INTRODUCTION

Muscle wasting is a recognised feature of critical illness and has obvious implications for patient rehabilitation and recovery. Whilst many clinicians believe lean tissue repletion to be a slow process following critical illness, and a probable explanation for poor functional recovery of patients many months after resolution of the illness, we have found no studies quantifying body composition changes during patient recovery.

METHODS

A combination of assessment techniques were used to monitor changes in body composition (that is, fat, water, protein and mineral), following intensive care unit (ICU) discharge, in a 38-year-old female recovering from extrapontine myelinolysis. Assessments were made at discharge from the ICU and then again 1 month, 3 months, 6 months and 12 months later. Functional recovery (respiratory muscle and hand-grip strength) and quality of life (36-item Short-form Health Survey) were assessed at these same timepoints.

RESULTS

Twelve months after discharge from the ICU, and despite an extensive rehabilitation programme and improvements in respiratory muscle and hand-grip muscle strength, our patient was unable to return to full-time employment and continued to complain of fatigue. She had successfully regained weight and was back to her pre-illness body weight. Body composition measurements showed that an incredible 73% of the weight gained was due to an increase in body fat.

CONCLUSION

It is difficult to extrapolate the results of a single case to the wider ICU population, not least because the present patient sustained a significant neurological injury, but our data are the first to support the long-held belief that patient weight gain following critical illness is largely attributable to a gain in fat mass. The magnitude of body composition changes in the present patient are startling and support the need for longitudinal body composition data in a wider ICU population.

Physical consequences of critical illness

Patients who survive critical illness are at risk of permanent physical and functional deficits which decrease the health-related quality of life. The reasons for physical morbidity include the nature of and treatment for the inciting critical illness, new decrements in organ function and worsening of pre-existing organ dysfunction, and prolonged physical immobility and long intensive care unit stay.

Biochemical approaches for nutritional support of skeletal muscle protein metabolism during sepsis

Sepsis initiates a unique series of modifications in the homeostasis of N metabolism and profoundly alters the integration of inter-organ cooperatively in the overall N and energy economy of the host. The net effect of these alterations is an overall N catabolic state, which seriously compromises recovery and is semi-refractory to treatment with current therapies. These alterations lead to a functional redistribution of N (amino acids and proteins) and substrate metabolism among injured tissues and major body organs. The redistribution of amino acids and proteins results in a quantitative reordering of the usual pathways of C and N flow within and among regions of the body with a resultant depletion of the required substrates and cofactors in important organs. The metabolic response to sepsis is a highly integrated, complex series of reactions. To understand the regulation of the response to sepsis, a comprehensive, integrated analysis of the fundamental physiological relationships of key metabolic pathways and mechanisms in sepsis is essential. The catabolism of skeletal muscles, which is manifested by an increase in protein degradation and a decrease in synthesis, persists despite state-of-the-art nutritional care. Much effort has focused on the modulation of the overall amount of nutrients given to septic patients in a hope to improve efficiencies in utilisation and N economies, rather than the support of specific end-organ targets. The present review examines current understanding of the processes affected by sepsis and testable means to circumvent the sepsis-induced defects in protein synthesis in skeletal muscle through increasing provision of amino acids (leucine, glutamine, or arginine) that in turn act as nutrient signals to regulate a number of cellular processes.

Metabolic support in sepsis and multiple organ failure: more questions than answers

The metabolic support of critically ill patients is a relatively new topic of active research and discussion, and surprisingly little is known about the effects of critical illness on metabolic physiology and activity. The metabolic changes seen in critical illness are highly complex, and how and when to treat them are only just beginning to be determined. Studies have demonstrated that the acute phase and the later phase of critical illness behave differently from a metabolic point of view for many organs, and while many of the alterations in metabolism seen during early critical illness may be appropriate and beneficial responses to cellular stress, whether this is true for all the metabolic alterations in all forms of critical illness is unclear. Currently we face more questions than answers, and further study is needed to elucidate the various components of the metabolic response to acute and chronic critical illness and to develop better techniques to assess and monitor these changes so that we can determine which therapeutic approaches should be used in what combinations and in which patients.

Metabolism modulators in sepsis: Propranolol

Sepsis is accompanied by an enormous increase in catecholamine expression, leading to metabolism of lipids and glucose, changes in cardiovascular output, immunomodulatory effects, and changes in protein metabolism, all of which push the body into a catabolic state. Deleterious beta-adrenoceptor controlled responses to stress and sepsis are well documented; therefore, it would seem appropriate to use propranolol under such circumstances. There are arguments both for and against the use of beta-adrenoceptor blockade during episodes of stress and infection. The definition of sepsis itself is a clinical one in most cases. There are guidelines concerning the diagnosis of sepsis (systemic inflammatory response syndrome [SIRS] in the presence of significant infection). However, when the cause of SIRS is not infection, for example, in burn patients, is it not possible, and indeed preferable, to tackle the stress response in a more aggressive fashion? The effects of SIRS on the body are myriad and have been defined and illustrated in many fine reviews. The effects of sepsis on the body, as well, have been discussed in the world literature and are beyond the scope of this article. In this article we attempt to demonstrate the effects of sepsis (SIRS plus infection) on whole body metabolism, outline the mediators of these changes, and then show the ability of propranolol to attenuate the changes seen.

Controversies in the determination of energy requirements

To avoid any negative outcomes associated with under- or overfeeding it is essential to estimate nutrient requirements before commencing nutrition support. The energy requirements of an individual vary with current and past nutritional status, clinical condition, physical activity and the goals and likely duration of treatment. The evidence-base for prediction methods in current use, however, is poor and the equations are thus open to misinterpretation. In addition, most methods require an accurate measurement of current weight, which is problematic in some clinical situations. The estimation of energy requirements is so challenging in some conditions, e.g. critical illness, obesity and liver disease, that it is recommended that expenditure be measured on an individual basis by indirect calorimetry. Not only is this technique relatively expensive, but in the clinical setting there are several obstacles that may complicate, and thus affect the accuracy of, any such measurements. A review of relevant disease-specific literature may assist in the determination of energy requirements for some patient groups, but the energy requirements for a number of clinical conditions have yet to be established. Regardless of the method used, estimated energy requirements should be interpreted with care and only used as a starting point. Practitioners should regularly review the patient and reassess requirements to take account of any major changes in clinical condition, nutritional status, activity level and goals of treatment. There is a need for large randomised controlled trials that compare the effects of different levels of feeding on clinical outcomes in different disease states and care settings.

Altered nutrition state in the severe multiple trauma patients undergoing adjuvant recombinant human growth hormone nutritional support therapy

In order to observe the nutrition state in the severe multiple trauma patients undergoing adjuvant recombinant human growth hormone (rhGH) nutritional support therapy, 45 patients with severe multiple traumas (ISS>25) were randomly divided into 3 groups. All the 3 groups had been supplied with nitrogen and caloricity according to the need of patients for 16 days. The rhGH therapy started 48 h after surgery and lasted for 14 days in two rhGH-treated groups in which rhGH was 0.2 and 0.4 U/(kg . d) respectively, and the resting group served as control one. The levels of nitrogen balance, prealbumin and safety variables (blood sugar, Na+, TT3 and TT4) were observed and compared among the three groups. The levels of nitrogen balance on the postoperative day (POD) 3 and 5 in the rhGH-treated groups were -1.28+/-3.19, 5.45+/-2.00 and -0.18+/-2.55, 6.11+/-1.60, respectively, which were significantly higher than those in the control group (-5.17+/-1.68 and -1.08+/-3.31, P<0.01). The values of prealbumin on the POD 3 and 5 in the rhGH-treated groups were 180.19+/-27.15, 194.44+/-50.82 and 194.94+/-29.65, 194.11+/-16.17, respectively, which were significantly higher than those in the control group (117.42+/-19.10 and 135.63+/-28.31, P<0.01). There was no significant difference between the rhGH 0.2 U/(kg . d) group and rhGH 0.4 U/(kg . d) group in both of the levels of nitrogen balance and prealbumin. It is concluded that the nutritional support therapy with adjuvant rhGH which starts 48 h after surgery improves the nutrition state of the patients with severe multiple trauma. It is safe for severe multiple trauma patients who accept rhGH at the dose of 0.2 and 0.4 U/(kg . d).

Effect of late-onset sepsis on energy expenditure in extremely premature infants

The purpose of this study was to compare total energy expenditure (TEE) in extremely premature infants during and after an episode of sepsis. We hypothesized that TEE in the sepsis group (SEP) would be higher during the septic period and higher than an age-matched control group (CTL). We further hypothesized that the TEE of the SEP group during the recovery period would be similar to that of the CTL group. The doubly labeled water method was used to determine TEE in both groups. Infant characteristics were as follows: SEP group, n = 10, gestation = 26 +/- 1 wk, birth weight = 854 +/- 218 g; CTL group, n = 10, gestation = 26 +/- 1 wk, birth weight = 880 +/- 158 g. TEE of the SEP group during the septic period was significantly greater than during the recovery period (96 +/- 25 kcal/kg/d versus 55 +/- 17 kcal/kg/d) and significantly greater than the CTL group during the first study period (96 +/- 25 kcal/kg/d versus 67 +/- 12 kcal/kg/d). TEE in the SEP group during the recovery period was similar to the CTL group. These increases in TEE may contribute to impaired growth and need to be considered when providing nutritional support for extremely premature infants.

Fluid, electrolytes and nutrition: physiological and clinical aspects

Fluid and electrolyte balance is often poorly understood and inappropriate prescribing can cause increased post-operative morbidity and mortality. The efficiency of the physiological response to a salt or water deficit, developed through evolution, contrasts with the relatively inefficient mechanism for dealing with salt excess. Saline has a Na+:Cl-of 1:1 and can produce hyperchloraemic acidosis, renal vasoconstriction and reduced glomerular filtration rate. In contrast, the more physiological Hartmann's solution with a Na+:Cl-of 1·18:1 does not cause hyperchloraemia and Na excretion following infusion is more rapid. Salt and water overload causes not only peripheral and pulmonary oedema, but may also produce splanchnic oedema, resulting in ileus or acute intestinal failure. This overload may sometimes be an inevitable consequence of resuscitation, yet it may take 3 weeks to excrete this excess. It is important to avoid unnecessary additional overload by not prescribing excessive maintenance fluids after the need for resuscitation has passed. Most patients require 2–2·5 litres water and 60–100?mmol?Na\d for maintenance in order to prevent a positive fluid balance. This requirement must not be confused with those for resuscitation of the hypovolaemic patient in whom the main aim of fluid therapy is repletion of the intravascular volume. Fluid and electrolyte balance is a vital component of the metabolic care of surgical and critically-ill patients, with important consequences for gastrointestinal function and hence nutrition. It is also of importance when prescribing artificial nutrition and should be given the same careful consideration as other nutritional and pharmacological needs.