Metabolism during the postinjury period

Systemic inflammatory and gut microbiota responses to fracture in young and middle-aged mice

Age is a patient-specific factor that can significantly delay fracture healing and exacerbate systemic sequelae during convalescence. The basis for this difference in healing rates is not well-understood, but heightened inflammation has been suggested to be a significant contributor. In this study, we investigated the systemic cytokine and intestinal microbiome response to closed femur fracture in 3-month-old (young adult) and 15-month-old (middle-aged) female wild-type mice. Middle-aged mice had a serum cytokine profile that was distinct from young mice at days 10, 14, and 18 post-fracture. This was characterized by increased concentrations of IL-17a, IL-10, IL-6, MCP-1, EPO, and TNFα. We also observed changes in the community structure of the gut microbiota in both young and middle-aged mice that was evident as early as day 3 post-fracture. This included an Enterobacteriaceae bloom at day 3 post-fracture in middle-aged mice and an increase in the relative abundance of the Muribaculum genus. Moreover, we observed an increase in the relative abundance of the health-promoting Bifidobacterium genus in young mice after fracture that did not occur in middle-aged mice. There were significant correlations between serum cytokines and specific genera, including a negative correlation between Bifidobacterium and the highly induced cytokine IL-17a. Our study demonstrates that aging exacerbates the inflammatory response to fracture leading to high levels of pro-inflammatory cytokines and disruption of the intestinal microbiota.

Risk factor analysis and construction of prediction models for short-term postoperative complications in patients undergoing gastrointestinal tract surgery

Purpose

To identify risk factors associated with short-term postoperative complications in patients with gastrointestinal cancer and develop and validate prediction models to predict the probability of complications.

Methods

A total of 335 patients enrolled in the primary cohort of this study were divided into training and validation sets in a chronological order. Using univariate and multivariate logistic regression analyses, the risk factors for postoperative complications were determined, and nomogram prediction models were constructed. The performance of the nomogram was assessed with respect to the receiver operator characteristic and calibration curves.

Results

Patients with complications had a stronger postoperative stress response and a longer duration of daily fluid intake/output ratio >1 after surgery. Logistic analysis revealed that body mass index (BMI), body temperature on POD4 (T.POD4), neutrophil percentage on POD4 (N.POD4), fasting blood glucose on POD4 (FBG.POD4), and the presence of fluid intake/output ratio <1 within POD4 were risk factors for POD7 complications, and that BMI, T.POD7, N.POD7, FBG.POD4, FBG.POD7, and the duration of daily fluid intake/output ratio >1 were risk factors for POD30 complications. The areas under the curve of Nomogram-A for POD7 complications were 0.867 and 0.833 and those of Nomogram-B for POD30 complications were 0.920 and 0.918 in the primary and validation cohorts, respectively. The calibration curves showed good consistency in both cohorts.

Conclusion

This study presented two nomogram models to predict short-term postoperative complications in patients with gastrointestinal cancer. The results could help clinicians identify patients at high risk of complications within POD7 or POD30.

Advances and Promises of Nutritional Influences on Natural Bone Repair

Impaired fracture healing continues to be a significant public health issue. This is more frequently observed in aging populations and patients with co-morbidities that can directly influence bone repair. Tremendous progress has been made in the development of biologics to enhance and accelerate the healing process; however, side-effects persist that can cause significant discomfort and tissue damage. This has been the impetus for the development of safe and natural strategies to hasten natural bone healing. Of the many possible approaches, nutrition represents a safe, affordable, and non-invasive strategy to positively influence each phase of fracture repair. However, our understanding of how healing can be hindered by malnutrition or enhanced with nutritional supplementation has lagged behind the advancements in both surgical management and the knowledge of molecular and cellular drivers of skeletal fracture repair. This review serves to bridge this knowledge gap as well as define the importance of nutrition during fracture healing. The extant literature clearly indicates that pre-existing nutritional deficiencies should be corrected, and nutritional status should be carefully monitored to prevent the development of malnutrition for the best possible healing outcome. It remains unclear, however, whether the provision of nutrients beyond sufficiency has any benefit on fracture repair and patient outcomes. The combined body of pre-clinical studies using a variety of animal models suggests a promising role of nutrition as an adjuvant therapy to facilitate fracture repair, but extensive research is needed, specifically at the clinical level, to clarify the utility of nutritional interventions in orthopedics. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:695-707, 2020.

Nutrition therapy: A new criterion for treatment of patients in diverse clinical and metabolic situations

OBJECTIVE

This study developed an instrument in table format to help determine the energy requirements of patients in adverse situations. The instrument allows for the weekly adjustment of nutrition therapy and energy intake, advocating a new approach to treatment based on clinical observation performed by staff specialized in individualized nutrition therapy.

METHODS

The table was elaborated by grouping patients according to the following criteria: criticality, chronicity, and stability of the clinical status. Energy supply was readjusted weekly to respect the cyclicity of the patient's metabolic response.

RESULTS

The table should be used in the following order: Obese > Elderly > Specific Clinical Situations > Chronic Diseases > Stable Clinical Situations. The protein requirements of patients with pressure ulcers or with wounds healing by secondary intention should be increased by 30% to 50%. Current patient weight should always be used, except in patients with anasarca. In these cases, the patient's last known dry weight or the ideal weight should be used. For elderly patients whose weight is not known and who cannot be weighed because of the patient's clinical condition, a body mass index of 23 should be assumed.

CONCLUSION

The proposed nutrition table allows for management of optimal energy and protein intake for patients in different clinical situations, while respecting the different phases of the posttraumatic metabolic response, thus leading to favorable clinical outcomes.

Alterations in energy substrate metabolism in mice with different degrees of sepsis

BACKGROUND

Nutritional management is crucial during the acute phase of severe illnesses. However, the appropriate nutritional requirements for patients with sepsis are poorly understood. We investigated alterations in carbohydrate, fat, and protein metabolism in mice with different degrees of sepsis.

MATERIALS AND METHODS

C57BL/6 mice were divided into three groups: control mice group, administered with saline, and low- and high-dose lipopolysaccharide (LPS) groups, intraperitoneally administered with 1 and 5 mg of LPS/kg, respectively. Rectal temperature, food intake, body weight, and spontaneous motor activity were measured. Indirect calorimetry was performed using a respiratory gas analysis for 120 h, after which carbohydrate oxidation and fatty acid oxidation were calculated. Urinary nitrogen excretion was measured to evaluate protein metabolism. The substrate utilization ratio was recalculated. Plasma and liver carbohydrate and lipid levels were evaluated at 24, 72, and 120 h after LPS administration.

RESULTS

Biological reactions decreased significantly in the low- and high-LPS groups. Fatty acid oxidation and protein oxidation increased significantly 24 h after LPS administration, whereas carbohydrate oxidation decreased significantly. Energy substrate metabolism changed from glucose to predominantly lipid metabolism depending on the degree of sepsis, and protein metabolism was low. Plasma lipid levels decreased, whereas liver lipid levels increased at 24 h, suggesting that lipids were transported to the liver as the energy source.

CONCLUSIONS

Our findings revealed that energy substrate metabolism changed depending on the degree of sepsis. Therefore, in nutritional management, such metabolic alterations must be considered, and further studies on the optimum nutritional intervention during severe sepsis are necessary.

Fast-track surgery improves postoperative clinical recovery and cellular and humoral immunity after esophagectomy for esophageal cancer

Background

Our aim was to investigate the influence of FTS on human cellular and humoral immunity using a randomized controlled clinical study in esophageal cancer patients.

Methods

Between October 2013 and December 2014, 276 patients with esophageal cancer in our department were enrolled in the study. The patients were randomized into two groups: FTS pathway group and conventional pathway group. The postoperative hospital stay, hospitalization expenditure, and postoperative complications were recorded. The markers of inflammatory and immune function were measured before operation as well as on the 1st, 3rd, and 7th postoperative days (POD), including serum level of interleukin-6 (IL-6), C-reactive protein (CRP), serum globulin, immunoglobulin G (IgG), immunoglobulin M (IgM), immunoglobulin A (IgA) and lymphocyte subpopulations (CD3 lymphocytes, CD4 lymphocytes, CD8 lymphocytes and the CD4/CD8 ratio) in the patients between the two groups.

Results

In all, 260 patients completed the study: 128 in the FTS group and 132 in the conventional group. We found implementation of FTS pathway decreases postoperative length of stay and hospital charges (P < 0.05). In addition, inflammatory reactions, based on IL-6 and CRP levels, were less intense following FTS pathway compared to conventional pathway on POD1 and POD3 (P < 0.05). On POD1 and POD3, the levels of IgG, IgA, CD3 lymphocytes, CD4 lymphocytes and the CD4/CD8 ratio in FTS group were significantly higher than those in control group (All P < 0.05). However, there were no differences in the level of IgM and CD8 lymphocytes between the two groups.

Conclusions

FTS improves postoperative clinical recovery and effectively inhibited release of inflammatory factors via the immune system after esophagectomy for esophageal cancer.

Trial registration

ChiCTR-TRC-13003562, the date of registration: August 29, 2013.

Mechanically Ventilated, Cardiothoracic Surgical Patients Have Significantly Different Energy Requirements Comparing Indirect Calorimetry and the Penn State Equations

BACKGROUND

Nutrition equations have been validated with indirect calorimetry for determining energy needs in intensive care unit (ICU) populations. This study tested the hypothesis that mechanically ventilated cardiothoracic surgical patients would have significantly different energy requirements when determined by indirect calorimetry vs the Penn State equations.

MATERIALS AND METHODS

This single-center, retrospective cohort analysis of consecutive cardiothoracic surgical patients adhered to a prospectively designed protocol for indirect calorimetry energy measurements. Energy needs were estimated by Penn State equations 2010 and 2003b and then indirect calorimetry.

RESULTS

Analyzed patients (n = 71) had a mean ± SD difference of 556 ± 543 calories/d between indirect calorimetry and Penn State formulae, as well as a mean ± SD percentage caloric difference of 32% ± 31% (95% confidence interval [CI], -20 to 87) with a range of 1311 calories (minimum difference, -379; maximum difference, 933). There was a 10% or greater difference in resting metabolic rate between indirect calorimetry and the Penn State equations in 89% of patients (95% CI, 79%-95%). Based on Lin's concordance correlation of 0.20 (95% CI, 0.09-0.32), the strength of agreement between the resting metabolic rates determined by indirect calorimetry compared with the Penn State equations was poor within this patient sample. Indirect calorimetry performance showed a 10% increase in caloric need in 77% of patients and was associated with a nutrition prescription change in 66%.

CONCLUSIONS

Mechanically ventilated cardiothoracic surgical ICU patients appear to have higher energy requirements by indirect calorimetry than those determined by Penn State equations. Future studies targeting indirect calorimetry in relation to clinical outcomes are needed.

An alternative point of view: getting by with less: what's wrong with perfection?

OBJECTIVE

Predictions about the future impact of technologic and process innovations inspire optimistic visions. Optimism and speculation require a counterweight. Because results often do not turn out as expected, anticipating failure is useful, and anticipating unintended consequences is visionary.

MEASUREMENTS

A history of unfulfilled prognostications was explored with the intent of finding something essential to the complexities of medicine. Do missed predictions signal another side to innovation that also helps us uncover new information about our world?

MAIN RESULTS

Serendipity is an important theme in medical innovation. There is no reason to think this will change. Things do not necessarily go as planned, but often the results are as important as the original prediction was supposed to be. It will not be clear where we end up until we get there.

CONCLUSIONS

Ideal goals are useful but speculative and subjective. There in fact might be several ideals and contingency is important. The detours and incidental stops on the way to an ideal are more fruitful than the goal itself.

Nutritional support of the pediatric trauma patient

Of all the interventions available to aid recovery of the injured child, few have the power of proper nutritional support. Healing after trauma depends not only on restoration of oxygen delivery, but on "substrate delivery," or provision of calories to support metabolic power and specific nutrients to allow rebuilding of injured tissue. Failure to deliver adequate substrate to the cells is revealed as another form of shock. Nutritional interventions after trauma are most effective when informed by the specific ways that children diverge physiologically (metabolic rate, biomechanics, physiological response to trauma) from adults. This review describes these responses and outlines a general strategy for safely delivering energy and specific substrates to protect and heal injured children, regardless of body size and type of injury.

The inflammatory response to surgery and trauma

PURPOSE OF REVIEW

The inflammatory or stress response to injury has evolved to ensure survival. This review will examine this response in otherwise healthy patients. Additionally, the impact of several common comorbid conditions on the inflammatory response will be considered. What will become evident is that the stress response may be exaggerated in some conditions and suppressed in others. Rapid identification of both an abnormal response and its cause will allow clinicians to maximize a patient's healing potential.

RECENT FINDINGS

Recent work has shown that an altered inflammatory response has marked effects on both immune competence and the endocrine system. Investigations are ongoing to delineate the mechanism of lymphocyte dysfunction. With regard to critical care endocrinopathies, the effects of insulin and hyperglycemia on inflammation and wound healing are being investigated.

SUMMARY

An understanding of the stress response will aid the clinician in preparing for expected responses, recognizing and perhaps correcting deviations from the norm and accounting for potential complications that arise in the face of preexisting disease. Deviations from the normal time course may represent the effects of preexisting medical illness, treatment or postoperative/injury complications.

Estimating energy expenditure in critically ill adults and children

Designing effective nutrition support regimens for critically ill patients requires an understanding of the energy needs of each patient. Many disease processes result in elevated caloric requirements, whereas some clinical procedures and medications may diminish the metabolic response. Experienced clinicians are unable to predict the extent to which trauma or injury will affect energy requirements for an individual. Both under- and overfeeding a critically ill patient may prolong hospitalization and increase morbidity and mortality. Applying equations that were originally developed for healthy nonhospitalized individuals to predict the energy requirements of critically ill patients will often result in significant errors and may lead to provision of inappropriate nutritional support. The measurement of resting energy expenditure by indirect calorimetry is a valuable tool and can be used to predict energy requirements for most spontaneously breathing critically ill patients, but may lead to spurious results in mechanically ventilated pediatric patients. In the complex and rapidly changing context of critical illness, individualized assessment of energy requirements is crucial. Whichever technique is used initially to assess energy requirements, sequential monitoring and constant reassessment of each patient is essential to provide the appropriate nutritional care regimen. The purpose of this article is to review the equations for estimating and the techniques, practical aspects, and interpretation of measuring energy expenditure in critically ill patients.

Nutritional follow-up of critically ill infants receiving short term parenteral nutrition

Few studies have tried to characterize the efficacy of parenteral support of critically ill infants during short period of intensive care. We studied seventeen infants during five days of total parenteral hyperalimentation. Subsequently, according to the clinical conditions, the patients received nutritional support by parenteral, enteral route or both up to the 10th day. Evaluations were performed on the 1st, 5th, and 10th days. These included: clinical data (food intake and anthropometric measurements), haematological data (lymphocyte count), biochemical tests (albumin, transferrin, fibronectin, prealbumin, retinol-binding protein) and hormone assays (cortisol, insulin, glucagon). Anthropometric measurements revealed no significant difference between the first and second evaluations. Serum albumin and transferrin did not change significantly, but mean values of fibronectin (8.9 to 16 mg/dL), prealbumin (7.7 to 18 mg/dL), and retinol-binding protein (2.4 to 3. 7 mg/dL) increased significantly (p < 0.05) from the 1st to the 10th day. The hormonal study showed no difference for insulin, glucagon, and cortisol when the three evaluations were compared. The mean value of the glucose/insulin ratio was of 25.7 in the 1st day and 15. 5 in the 5th day, revealing a transitory supression of this hormone. Cortisol showed values above normal in the beginning of the study. We conclude that the anthropometric parameters were not useful due to the short time of the study; serum proteins, fibronectin, prealbumin, and retinol-binding protein were very sensitive indicators of nutritional status, and an elevated glucose/insulin ratio, associated with a slight tendency for increased cortisol levels suggest hypercatabolic state. The critically ill patient can benefit from an early metabolic support.

Postoperative pattern of various hormonal and metabolic variables. A pilot study in patients without complications following cardiac surgery

The use of single predictors for threatening postoperative complications are widely accepted. However, a typical pattern of multiple parameters could be more helpful than a single predictor. To study this hypothesis, various variables of normal postoperative changes in patients without postoperative complications were investigated. Secondly, this pattern needs to be compared in the future with those findings in patients with postoperative complications. Blood parameters of 13 patients undergoing cardiovascular surgery without postoperative complications for 24 hours were evaluated. Samples were obtained on the afternoon before the operation and 1, 3, 6, 12 and 24 hours after the end of surgery. At one hour postoperation increased levels of the following parameters were noted: growth hormone (p < 0.0001), glucose (p < 0.0001), insulin (p < 0.001), c-peptide (p < 0.001), lactate (p < 0.002), glutamate (p < 0.0001), aspartate (p < 0.001) and total amino acids (p < 0.05), although the concentration of some amino acids decreased. Three hours postoperatively free fatty acids (p < 0.05) were increased. Total-T3 concentrations were reduced postoperatively. Other parameters were not altered. Most of the parameters returned to normal values during the period of observation.

Enteral nutrition and the critically ill

Critically ill patients invariably require nutritional intervention. Traditionally, enteral nutrition has not been widely employed in this patient population. This is due in part to the success of present-day parenteral nutrition, and to difficulties encountered with enteral feeding. Recent evidence has demonstrated that enteral is preferable to parenteral nutrition in terms of cost, complications, gut mucosal maintenance, and metabolic and immune function. Enterally administered nutritional support can and should be utilised as the preferred route of nourishment for the critically ill. The appropriate choice of access and formula, as well as a rational strategy for implementation, should improve the likelihood of success. This article describes the unique features of critical illness as they pertain to nutritional support, the benefits of enteral nutrition, and the obstacles to success, and offers suggestions which may improve the ability to provide nutrients adequately via the intestinal tract.

Nutritional and metabolic assessment of critically ill children

In a prospective study, with the objective of determining the metabolic profile, response to nutrient supply, and role of nutritional and metabolic assessment parameters in children admitted to a pediatric ICU, 11 patients in the age group 2-12 were studied. The assessment was carried out during the first 72 hours of admission, and again seven days later, and included the following parameters; caloric supply; nitrogen supply; prealbumin serum level; urinary urea nitrogen; nitrogen balance and creatinine-height index. The evolution of the parameters in the two stages of the study showed the following results: The urinary urea nitrogen median value at admission was 7.5 g/m2 of corporeal surface, and did not present significant changes seven days later. There was a significant increase in caloric supply from 42.9 to 70.3 kcal/kg, and in nitrogen supply, from 4.7 to 10.2 g/m2 of corporeal surface p 0.01. The level of nitrogen balance rose from -5.6 to 2.5 g/24 h (p < 0.03), and that of prealbumin, from 16.7 to 26.3 mg/dl (p < 0.03). There was a significant reduction in the creatinine-height index, from 86.2 percent to 55.0 percent p 0.01. The magnitude of urinary urea nitrogen excretion at admission varied 2.5-13.8 g/m2 of corporeal surface. Based on this parameter, it was not possible to establish a characteristic metabolic profile for the conditions studied. Notwithstanding an increase in the protein and caloric supply, prealbumin level and nitrogen balance observed in the second stage of the study, the patients lost muscle mass and entered into a malnutrition process, probably due to intense protein catabolism and the poor response to nutrition supply that occurs in metabolic stress.

Effect of ambient temperature on metabolic rate after thermal injury

OBJECTIVE

The authors describe the effect of ambient temperature on metabolic rate after thermal injury.

SUMMARY BACKGROUND DATA

Thermal injury induces a hypermetabolic state, which is reported to increase with the extent of burn. The magnitude of this response is further influenced by ambient temperature.

METHODS

The resting energy expenditure was measured by indirect calorimetry at ambient temperatures of 22, 28, 32, and 35 C. It was indexed to a calculated basal metabolic rate in normal volunteers and adult patients with burns involving at least 20% of the total body surface area who had no evidence of systemic infection. These measurements were performed between postburn days 6 and 21.

RESULTS

The effect of ambient temperature on metabolic rate was measured in 44 burn patients and 8 normal volunteers. Burn size ranged from 20 to 97% total body surface area with a mean of 44 +/- 18.5% total body surface area. Metabolic rate did not change significantly in control subjects as ambient temperature was varied (p<0.05). Regression analysis showed that burn size and ambient temperature were significant determinants (p<0.01) of metabolic rate in the patients and that together these factors accounted for 55% of the variation observed (df adj. r(2)=0.55) across the range of ambient temperatures studied. Metabolic rate was independent of burn size at ambient temperatures of 32 and 35 C (p<0.02) and increased by a factor of 1.5 X basal metabolic rate. A further increase in metabolic rate, which was positively correlated with burn size, resulted from nonshivering thermogenesis at ambient temperatures 28 and 22 C. The magnitude of this response was greatest at 22 C.

CONCLUSIONS

These findings suggest that the hypermetabolic response to thermal injury is maximal in burns as small as 20% total body surface area and that an additional burn size-dependent increase in metabolic rate results from heat loss at ambient temperatures below thermoneutrality.

Gut-derived proteolysis during insulin-induced hypoglycemia: the pain that breaks down the gut

The metabolic events associated with early response to injury have received little attention because of the confounding effects of the hemodynamic alterations that normally occur during this early phase. We have used a well established and reproducible model of insulin-induced hypoglycemia in the conscious dog to define the glucose and amino acid kinetic alterations as well as the hormonal and interorgan amino acid and gluconeogenic precursor flux characteristics of the "ebb" phase of postinjury metabolism. The results from our whole-body response have demonstrated on enhanced rate of whole body proteolysis and amino acid oxidation. The site of the majority of the proteolytic response has been demonstrated to be the extra-hepatic splanchnic tissues or gut. These findings have been supported by studies focusing on the specific organ changes, which have demonstrated alterations compatible with impaired proliferation at the level of the gut mucosa. Furthermore, the regulation of this gut-derived proteolysis has been demonstrated to be mediated by the glucopenia at the level of the central nervous system. The specific site of this response is still elusive; however, the mediators seem to involve not only the traditional hormonal and neurotransmitter pathways but also the release of endogenous opioids and opiates. Although a cause-effect relationship has not yet been demonstrated for the control of gut-derived proteolysis by opioids and opiates, we present evidence that leads us to hypothesize that relationship as a possible regulatory mechanism.

Multiple organ failure syndrome

Tissue injury, whether from infection, blood or volume loss, trauma, or inflammation such as pancreatitis, induces local and systemic responses. The systemic responses include shock, reperfusion, systemic inflammation (hypermetabolism) with primary organ dysfunction, and secondary organ dysfunction that either becomes progressive and leads to death or from which the patient recovers and enters into a period of prolonged rehabilitation. Each of these responses has its pathogenesis and treatments that are appropriate and effective. The research indicates that the responses may contribute to the development of cell and organ injury and to progressive multiple organ failure syndrome and death, particularly in the case of the systemic inflammatory response. Current therapy is designed to rapidly remove the cause of injury, resuscitate the microcirculation, and institute nutrition therapy to prevent single and generalized nutrient deficiencies and promote repair and healing. Newer therapies are designed to modulate the inflammatory response itself to minimize its injury potential and promote tissue repair and recovery of the patient. Genetic regulation of metabolism is also a pathogenetic mechanism. Its role in these responses is just starting to be understood--new therapies will need to await this understanding. Once the patient begins to recover, rehabilitation tends to be long and problematic. Nonetheless, significant survival rates are now occurring, with continued improvements expected in response to the newer therapeutic approaches. Planned rehabilitation thus becomes an important component of effective recovery. Professionals trained in critical care and well versed in cellular and molecular biology provide the milieu within which continued improvements in prevention, therapy, and outcome will continue to occur.

Pediatric burns. An overview

This article describes the management of burn injuries in children. It begins with an epidemiologic description of pediatric burns. Attention is given to emergency care, burn wound evaluation, operative management, and rehabilitative goals.

Role of nutrition in the management of malnutrition and immune dysfunction of trauma

Current nutrition support improves patient outcome in trauma patients. It appears to do so by limiting the adverse effects of specific nutrient or generalized nutrient deficiencies. Immunosuppression, however, continues as a significant clinical problem. This immunosuppression appears to be part of the inflammatory response that accompanies trauma, and in part, to represent the need for conditional nutrients in this setting. Three nutrients that are being evaluated include arginine, uracil as ribonucleic acid and omega-3 polyunsaturated fatty acids. Animal studies report improved immune function. Early clinical trials are reporting improved immune function and patient outcomes.

Nutritional consequences of major gastrointestinal surgery. Patient outcome and starvation

Advances in major gastrointestinal surgery and the existence of a significant number of high-risk patients necessitate a detailed knowledge of the metabolic response to surgery and the need for adjunctive nutritional therapy. Such surgery has the potential to cause significant nutritional consequences affecting patient outcome. Often, patients present malnourished preoperatively because of their chronic gastrointestinal disease, advanced age, or comorbidity. Still others are at great risk for developing malnutrition postoperatively secondary to the hypercatabolism of prolonged illness or postoperative complications. In addition, the surgical alterations of the gastrointestinal tract might disrupt normal function sufficiently to result in chronic nutritional deficiencies. Because starvation is no longer an acceptable condition, these concerns need to be recognized prior to surgery, and if indicated, nutritional support must be initiated preoperatively. Placement of feeding jejunostomy catheters for early enteral support should be considered for all high-risk patients. Equally important, surgeons should maintain a watch for future nutritional innovations that will improve their ability to meet patients' nutritional requirements.

Do parenteral nutrition solutions with high concentrations of branched-chain amino acids offer significant benefits to stressed patients?

The critically ill, stressed patient has been characterized as having altered cellular metabolism. Altered protein metabolism is manifested as negative nitrogen balance, reduced whole-body protein synthesis, and increased proteolysis. An increased oxidation of the branched-chain amino acids (BCAA) leucine, isoleucine, and valine has also been observed. Exogenous administration of BCAA as part of a total parenteral nutrition (TPN) regimen has been proposed to compensate for the altered protein metabolism in the stressed patient by sparing endogenous sources of BCAA, thereby reducing skeletal muscle catabolism and increasing protein synthesis. Numerous clinical studies have been performed investigating this theory. The results are controversial. Differences in study outcomes appear to be related to study design, especially patient selection. Our review of those studies which were randomized, prospective, and controlled indicates that an improvement in nitrogen retention and visceral protein status can be achieved in stress-stratified patients who receive a TPN regimen containing a BCAA-enriched formula. The significance of these outcomes on morbidity, length of hospital stay, and mortality has not been evaluated.

Isotopic studies during surgical convalescence

We have performed paired isotopic studies in four patients undergoing resection of early colorectal cancer and four having removal of parathyroid adenomas. Kinetic measurements of protein and glucose metabolism were made before resection and at home 10 weeks after surgery. During convalescence there were major changes in both groups in glucose metabolism and the hormonal milieu despite no alterations in protein kinetics or metabolic rate. In particular, the rate of glucose production doubled from (mean +/- s.e.m.) 14.8 +/- 1.3 to 28.1 +/- 2.5 mumol kg-1 min-1 (P less than 0.01), the percentage of available glucose undergoing oxidation decreased from 35.5 +/- 3.9 to 21.5 +/- 2.9 per cent (P less than 0.05) and the percentage of glucose undergoing recycling to lactate increased from 20.1 +/- 10.0 to 52.9 +/- 2.3 per cent (P less than 0.05). During convalescence the basal plasma insulin concentration was significantly higher (P less than 0.05) and there was a proportionately smaller response to glucose infusion. The convalescent state was also associated with an elevation in serum cortisol from 291 +/- 54 to 496 +/- 75 nmol litre-1 (P less than 0.05). The values for resting energy expenditure were not significantly different from the predicted energy expenditure in either the preoperative or the convalescent groups. We conclude that (a) there is a marked increase in both glucose production and glucose recycling to lactate in convalescence from clean uncomplicated surgery, and this is associated with a decrease in the percentage of glucose uptake oxidised; (b) a relative hyperinsulinaemia is seen in convalescent patients and is associated with decreased responsiveness to a glucose load; (c) the plasma cortisol level is significantly elevated after 10 weeks of convalescence; and (d) convalescent patients do not have elevated rates of protein catabolism or energy expenditure.

The metabolic and nutritional effects of injury and sepsis

The existence of a co-ordinated response to stress of a variety of causes has clearly been established. Basically, this consists of an elevation in energy expenditure and an increased breakdown of skeletal muscle protein. In addition, glucose level in the plasma increases as a result of increased synthesis and decreased uptake of glucose into cells. Release of fatty acid into the plasma is also increased, and an elevation in the proportion of energy derived from oxidation of fatty acids is observed. This response is qualitatively very different from that seen in simple starvation, where a progressive reduction in energy expenditure and a reduction in the synthesis of glucose allows fat to become the major energy-producing substrate and also allows sparing of body protein stores. The mechanisms responsible for this altered pattern of metabolism are probably primarily hormonal in nature, with adrenaline, cortisol and glucagon being the major catabolic stimulants. Some evidence exists, however, for alteration in intracellular pathway metabolism. Within the past decade a new class of mediators of the stress response, the cytokines, has been recognized. These substances are protein products of circulating monocytes and the way in which they integrate into the control of the stress response has not been completely elucidated. At present there is evidence that they can stimulate production of catabolic hormones, and also they may well have direct effects in enhancing protein catabolism in muscle. At present the main method for modification of the stress response remains the provision of energy and amino acid, either intravenously or enterally. In the present state of our knowledge, 30-40 kcal kg-1 day-1 would appear to be adequate for most patients, with half provided as fat. Amino acids 3 g kg-1 day-1 will provide adequate nitrogen. It must be said, however, that the most effective method of modifying the stress response is removal of the source of stress by surgery, antibiotics or other primary therapy.

Contribution of the urea appearance rate to diuretic-induced azotemia in the rat

Studies were performed to evaluate the contribution of the urea appearance rate to the elevated plasma urea concentration found during diuretic-induced sodium depletion. Negative sodium balance of -1162 + 29 microEq/100 g body wt was induced over a four day period by the administration of furosemide, 20 to 30 mg/kg/d i.p., to rats ingesting a sodium free diet. When compared with sodium replete controls, sodium depletion significantly increased the plasma urea concentration (65.0 +/- 3.1 vs. 26.4 +/- 1.1 mg/dl) through both an increase in the urea appearance rate (160 +/- 5.2 vs. 125 +/- 3.5 mg/day/100 g body wt), and a decrease in the urea clearance rate (1.99 +/- 0.14 vs. 3.16 +/- 0.12 ml/min/kg). The urea appearance rate increased on the first day of diuretic administration, remained elevated three days after stopping diuretics, rapidly returned to control levels after sodium repletion, and was significantly correlated with the magnitude of sodium deficit. Similar results were obtained when diuretic-induced sodium depletion was produced in adrenalectomized animals. After four days of sodium depletion the plasma concentration was increased for some amino acids but not for the plasma total amino acid, nitrogen concentration. The results indicate that sodium depletion increases the urea appearance rate through a mechanism that is independent of adrenal function. Thirty to sixty percent of the elevation in plasma urea concentration that occurs in the rat during diuretic-induced sodium depletion can be accounted for by an enhanced urea appearance rate.

The effect of stress level, amino acid formula, and nitrogen dose on nitrogen retention in traumatic and septic stress

Eighty-seven patients were entered into a randomized, prospective, double-blind, six-center study to evaluate the effect of amino acid loading and a formula that was branched chain enriched (50%) on nitrogen retention in metabolic stress. The patients had varying levels of metabolic stress (0-3) after major surgery, polytrauma, or surgical sepsis. The study was isocaloric and isonitrogenous and lasted for 7 days. The patients received either a standard amino acid formula (SAA) (Travasol) or a 50% branched chain enriched formula that was equimolar, leucine, isoleucine, and valine (MAA) (Travasol + Branchamin concentrate) at a dose of 1.0-2.0 g/kg/day in a fixed ratio with 114 glucose calories per gram of nitrogen administered. The nitrogen retention was proportionate to the nitrogen (and, therefore, caloric) load in both groups. The MAA group, however, had better nitrogen retention, reached nitrogen equilibrium at a lower dose of amino acids, and had less urinary nitrogen excretion per gram of nitrogen administered. Since the groups were isonitrogenous and the calorie to nitrogen ratios were fixed, it appears that nitrogen equilibrium in surgical stress is proportionate to the amino acid load over a range of 0.05-0.4 g/kg/day of nitrogen; and that MAA are more efficient at inducing nitrogen retention and a reduction in urea excretion. These effects on nitrogen retention were more significant at level 2 stress or greater. At these higher stress levels, a dose of 2 +/- 0.2 g/kg/day of MAA seemed most efficient in promoting nitrogen retention.

Prostaglandin E2 and muscle protein turnover in Pseudomonas aeruginosa sepsis

Rats were injected intraperitoneally with Pseudomonas aeruginosa (septic group) or sterile 0.9% NaCl (controls). Soleus muscles were excised 7 h later, and muscle prostaglandin E2 release and tyrosine release were measured in vitro. Muscles of septic rats exhibited 226-326% higher release of prostaglandin E2 and 54-84% higher net proteolysis than muscles of controls. Inclusion of aspirin or indomethacin in the incubation medium almost completely inhibited prostaglandin E2 production, but had no effect on net proteolysis in muscles from either group. Inclusion of cycloheximide, a protein synthesis inhibitor, increased tyrosine release of control muscles by 42%, whereas no statistically significant increase was observed in muscles from infected rats. However, total proteolytic rate, indexed by tyrosine release in the presence of cycloheximide, was 22% higher in muscles of septic rats compared to that of control animals. Concomitantly, inclusion of cycloheximide inhibited prostaglandin E2 release by muscles of infected rats by 91% and that of controls by 65%. It is concluded that muscles of septic animals exhibit a pronounced stimulation of prostaglandin E2 release and net proteolysis, combined with a small increase in total proteolytic rate, the stimulation of net proteolysis is mainly due to inhibition of protein synthesis, the increases in net and total proteolysis appear to be independent of prostaglandin E2 production, cycloheximide has a previously unrecognized inhibitory effect on muscle prostaglandin E2 production.

Metabolic response to experimental trauma: the time relation of post-traumatic protein metabolism

The relationship between time and the post-traumatic metabolic response was studied in a commonly used experimental model of trauma. Twenty nine rats underwent laparotomy and jugular vein sham catheterization as the standard trauma. The rats were fed ad libitum and compared to pair fed controls in terms of nitrogen balance and liver protein synthesis. The pairs of rats were divided into three groups according to the duration of the experiment, which was 24 h, 48 h or 72 h. The nitrogen balance was calculated daily and the liver protein synthesis in vitro measured in 10 rats after 48 h with an asanguinous perfusion system using L-(1-C(14))-Leucine. The metabolic effect of trauma was first detected in liver protein synthesis, which was diminished in the early post-traumatic period (percentage synthesis rates: post-traumatic 34.6 +/- 10.7 and pair fed 60.4 +/- 21.3, Mean +/- SD, P < 0.05). During this period the whole body nitrogen balances were similar (post-traumatic -1.200 +/- 1.440 and pair fed -0.880 +/- 1.130, gN/kg/48 h, mean +/- SD). On the third day, the response to nitrogen intake and the nitrogen balance became significantly worse in the post-traumatic rats (post-traumatic 0.214 +/- 1.680 and pair fed 1.236 +/- 1.220, gN/kg/day, mean +/- SD). These observations suggest that, firstly, the 'flow' phase has its onset on the third post-trauma day, and secondly that trauma does decrease liver protein synthesis, and this decrease lasts at least through the 'ebb' phase. The results indicate the necessity of defining the metabolic phase in experimental studies of post-traumatic metabolism.

Branched chain metabolic support. A prospective, randomized, double-blind trial in surgical stress

A prospective, randomized, double-blind trial of the nutritional effects of branched chain modified amino acid solutions was undertaken in 23 surgical patients within 24 hours of the onset of major general surgery, polytrauma, or sepsis. The effects were evaluated in the absence of abnormalities of oxygen transport and perfusion in an isocaloric/isonitrogenous setting where the major difference between the groups was the amount of branched chain amino acids received. Both groups received balanced parenteral nutrition with 1.5 gm/kg/day of amino acids, 30 calories/kg/day of glucose, and 7 calories/kg/day of fat. At the end of the 7-day study interval, the group receiving the branched chain enriched therapy at 0.7 gm/kg/day of branched chain amino acids had improved nitrogen retention; an elevation of their absolute lymphocyte count from 800 to 1800/mm3, a reversal of anergy to recall skin test antigens in 60% of the patients, and improved plasma transferrin levels (p less than 0.03). Nutritional support using the modified amino acid metabolic support solutions has beneficial effects during the stress interval that do not seem as achievable with current commercially available nutritional support regimens.

Biological time-related changes in tolerance of male rats to hypoxia--I. Survival rate and carbohydrate metabolism

Investigations were carried out on male Wistar rats, synchronized in standard conditions to a light-dark regiment (LD 12:12 with L from 0600 to 1800). Rats exposed to hypoxia equivalent to 10,500m at a clock-hour of 1000 had a survival time twice as long as that of animals exposed at 2200. Data from this study indicate the ability to mobilize energy stores through the conversion of liver glycogen to glucose along with circadian differences in hormonal response (e.g. corticosterone and insulin) contributes to the tolerance to hypoxia being greater during diurnal rest than nocturnal activity in rats.

Does modified amino acid total parenteral nutrition alter immune-response in high level surgical stress

A randomized prospective double-blinded study was conducted in patients in moderate to high level surgical stress to ascertain the effect of high dose branched-chain (BcAA) hyperalimentation on skin test reactivity and lymphocyte count. Isocaloric, isonitrogenous balanced total parenteral nutrition solutions were administered to two treatment groups. The study group received the high dose (45% BcAA) solution while the control group received a standard amino acid solution (24.2% BcAA). All patients received 1 to 1.5 g/kg/day of amino acids and 30 nonprotein cal/kg/day, with 30% of them as fat. Immune function was assessed by absolute lymphocyte count and delayed cutaneous hypersensitivity on days 0 and 7 of therapy. Absolute lymphocyte count showed a marked improvement in patients receiving high dose aBcAA (p less than 0.03). All patients were anergic at baseline; a much greater percentage of skin test reactivity was observed in the BcAA group on day 7 (p less than 0.03). They were also in positive nitrogen balance. The data suggest that improved nitrogen retention and immune-competence is possible with branched-chain-enriched hyperalimentation in high level surgical stress.

Recurrent ventricular tachycardia associated with gangrene

Ventricular tachycardia occurs with myocardial ischaemia, hypoxia, hypercarbia, hypokalaemia, and digitalis toxicity. We report recurrent ventricular tachycardia occurring in a patient with gangrene of the lower extremities in whom none of the common aetiologies for dysrhythmia could be demonstrated. Ventricular tachycardia stopped and did not recur after amputation. This course leads us to speculate that release of a toxic substance from gangrenous tissue may contribute to the development of ventricular tachycardia.

Metabolic response to surgery in the cancer patient: consequences of aggressive multimodality therapy

The metabolic response to uncomplicated surgery in the patient undergoing primary therapy for malignancy is no different than the response to surgery of similar magnitude for benign disease. Hemodynamic, nutritional-endocrine, and convalescent changes are similar. However, with current aggressive approaches to the management of cancer, the patient often comes to surgery with evidence of major debilitating side effects from his progressive malignancy or from aggressive multimodality therapy. The surgeon must be aware of the consequences of the use of combination therapies on the expected metabolic response to surgery. Awareness of such problems such as the nutritional deficit will allow preventive methods to supercede metabolic salvage procedures.

Alterations in the enzyme profile in intensive care patients undergoing total parenteral nutrition

Total parenteral nutrition (TPN) has been demonstrated to be an effective therapeutic means in improving the clinical course of the critically ill patients. Various metabolic complications are described; the cause of some of these remain unclear. The changes in some plasma enzyme indices (GOT, GPT, GIDH, LDH, HBDH, CPK, ChE, AP, gamma-GT) in two groups of critically ill patients undergoing TPN (group with more marked enzyme alterations and group with less marked alteration) were examined. Two types of alterations were found: (1) early increase of some enzymes (GOT, GPT, GIDH); (2) constant increase of plasma enzyme level during TPN (AP, gamma GT). These two evolutionary patterns were more evident in the complicated group and the enzyme changes were statistically significant for GOT and GPT (P = 0.05) and not significant for initial values of G1DH, ap and gamma-GT. Both groups presented constant elevated plasma values of LDH, HBDH, CPK and depressed constant ChE value during treatment; the difference was not significant in both groups for the same enzymes. The data were interpreted from a functional point of view; that is they were related to both the metabolic post-aggressive state and TPN. A relationship between the rate of protein catabolism and the inductive increase of some enzymes (GOT, GPT, G1DH) was found. Whereas a final induction in the energy metabolism is suggested for other enzymes (LDH, HBDH), the alteration of CPK, AP, gamma-GT and ChE was interpreted as dependent on: (1) direct muscular trauma (CPK); (2) functional increase in relation to the duration of TPN (AP and gamma-GT); (3) possible depressed malnutritive synthesis (ChE). The improvement of the enzymatic patterns with the early use of TPN and with the improvement of clinical and nutritional conditions was emphasized.