Early hormonal changes affect the catabolic response to trauma

Trauma-related electrolyte disturbances: From resuscitation to rhabdomyolysis

Traumatic injury results in drastic changes to a patient's normal physiology. The hormonal stress response, as well as some treatment strategies, lead to significant disruptions in electrolyte homeostasis that are important for clinicians to understand. In addition, advances in fluid resuscitation and modern transfusion practices have led to their own unique set of consequences, which we are just beginning to appreciate. Special attention is placed on rhabdomyolysis, as this distinct entity represents an extreme example of injury induced electrolyte derangements. This review describes the physiologic response to trauma and highlights some of the important electrolyte abnormalities that can be encountered while caring for the injured patient.

Determination of Serum Levels of Interleukin-6, Interleukin-8, Interleukin-10, and Tumor Necrosis-Alpha and their Relationship With The Total Body Surface Area in Children

There are few studies on the inflammatory processes and the role of cytokines involved in pediatric burn injuries. The present study aims to measure the serum levels of cytokines and their relationship with the degree of burn injury in children. Within the 48 hours of hospitalization, the serum samples were obtained to measure inflammatory cytokines (interleukin-6, interleukin-8, interleukin-10 [IL-6, IL-8, and IL-10] and tumor necrosis factor-alpha [TNF-α]). The level of all of these cytokine factors was assessed by enzyme-linked immunosorbent assay technique. The mean levels of IL-6, IL-8, IL-10, and TNF-α was 18.15 ± 4.77 pg/ml, 59.54 ± 4.59 pg/ml, 8.41 ± 2.09 pg/ml, and 1.48 ± 0.15 pg/ml, respectively, which were higher than the normal range designated for the healthy pediatrics age group. The levels of TNF-α were higher in patients with sepsis (P = .03) and deceased patients (P = .001). There was a statistically significant difference in the levels of IL-8 in patients with second- (.001) and third-degree (.001) burn injuries in comparison to the first-degree burn injuries, and the level of IL-8 was statistically significantly higher in patients with electrical burn injuries in comparison to scald burn injuries (.01). IL-10 was statistically significantly higher in patients with contact burn injuries in comparison to scald (.001) and flame (.03) burn injuries. Cytokine levels in pediatric burn patients increased after severe burn injuries. There was a significant correlation between the levels of IL-8 and the degree of burn injuries.

Post-Cesarean Opioid Use after Implementation of Enhanced Recovery after Surgery Protocol

OBJECTIVE

This study aimed to evaluate whether implementation of an enhanced recovery after surgery (ERAS) protocol is associated with lower maternal opioid use after cesarean delivery (CD).

STUDY DESIGN

We performed a pre- and postimplementation (PRE and POST, respectively) study of an ERAS protocol for cesarean deliveries. ERAS is a multimodal, multidisciplinary perioperative approach. The four pillars of our protocol include education, pain management, nutrition, and early ambulation. Patients were counseled by their outpatient providers and given an educational booklet. Pain management included gabapentin and acetaminophen immediately prior to spinal anesthesia. Postoperatively patients received scheduled acetaminophen and ibuprofen. Oxycodone was initiated as needed 24 hours after spinal analgesia. Preoperative diet consisted of clear carbohydrate drink consumed 2 hours prior to scheduled operative time with advancement as tolerated immediately postoperation. Women with a body mass index (BMI) <40 kg/m² and scheduled CD were eligible for ERAS. PRE patients were randomly selected from repeat cesarean deliveries (RCDs) at a single site from October 2017 to September 2018, BMI <40 kg/m², without trial of labor. The POST cohort included women who participated in ERAS from October 2018 to June 2019. PRE and POST demographic and clinical characteristics were compared. Primary outcome was total postoperative morphine milligram equivalents (MMEs). Secondary outcomes included length of stay (LOS) and maximum postoperative day 2 (POD2) pain score.

RESULTS

All women in PRE (n = 70) had RCD compared with 66.2% (49/74) in POST. Median total postoperative MMEs were 140.0 (interquartile range [IQR]: 87.5-182.5) in PRE compared with 0.0 (IQR: 0.0-72.5) in POST (p < 0.001). Median LOS in PRE was 4.02 days (IQR: 3.26-4.27) compared with 2.37 days (IQR: 2.21-3.26) in POST (p < 0.001). Mean maximum POD2 pain score was 5.28 (standard deviation [SD] = 1.86) in PRE compared with 4.67 (SD = 1.63) in POST (p = 0.04).

CONCLUSION

ERAS protocol was associated with decreased postoperative opioid use, shorter LOS, and decreased pain after CD.

KEY POINTS

· ERAS protocol was associated with decreased postoperative opioid use after CD.. · ERAS protocol was associated with shorter length of stay after CD.. · ERAS protocol was associated with decreased postoperative pain after CD..

Anti-Hyperglycemic Activity of Zinc Plus Cyclo (His-Pro) in Genetically Diabetic Goto-Kakizaki and Aged Rats

We previously reported that treatment of streptozotocin-induced diabetic rats with zinc plus cyclo (his-pro) (CHP) decreased fed blood glucose levels and water intake. The present study was conducted to examine the dose-dependent, acute, and chronic treatment effects of CHP on oral glucose tolerance (OGT), fed blood glucose levels, water intake, and plasma insulin levels in young and aged Sprague-Dawley (S-D) rats, nondiabetic Wistar rats, and genetically diabetic Goto-Kakizaki (G-K) rats. Acute gastric gavage of 10 mg zinc plus 1.0 mg CHP/kg body weight significantly improved OGT in 4- and 13-month-old nondiabetic S-D rats and in 2-month-old diabetic G-K rats. Young S-D and G-K rats returned to pretreatment OGT values 1 week after acute gavage of zinc plus CHP (ZC), but improved OGT values persisted for at least 1 week after gavage in aged S-D rats. OGT values and fed blood glucose decreased to the greatest extent among other treatments when G-K rats were given free access to drinking water containing 1.0 to 1.5 mg CHP/L plus 10 mg zinc/L for 2 weeks. Although food and water intake showed a tendency to decrease, no statistically significant differences were observed in young G-K rats. Plasma insulin levels and blood glucose levels in both normal and diabetic G-K rats decreased with 2-week treatment with ZC. To test the direct effects of ZC on muscle tissue, we observed the effect of various doses of ZC on normal and G-K rat muscle slices. The optimal level of CHP alone for maximal muscle glucose uptake in muscle slices from normal rats was 10 microg/mL and 5.0 microg/mL in G-K rats, and ZC stimulated glucose uptake. However, no statistically significant difference was demonstrated between normal and G-K rat tissues in this study. These results indicate that oral intake of an optimal dose of ZC stimulates blood glucose metabolism, probably by stimulating muscle glucose utilization.

Glycaemic control in trauma patients, is there a role?

Stress-induced hyperglycaemia is a significant problem in critically ill patients, including those with surgical or traumatic injury in the intensive care unit (ICU). The severity of hyperglycemia and insulin resistance reflect the risk of death. A recent, large, prospective, randomized, controlled study showed that maintaining normoglycemia with intensive insulin therapy improves survival and reduces morbidity in a surgical ICU population. Recent data from observational studies has confirmed the clinical benefits of glycaemic control in both surgical and mixed surgical/medical ICU conditions. Titrating insulin to normoglycaemia appears to be crucial in order to achieve most clinical benefits. Prevention of glucose toxicity protects the endothelium as well as ultrastructure and function of hepatocyte mitochondria. Other metabolic and non-metabolic effects of the insulin administered contribute to the clinical benefits, including a partial correction of the deranged serum lipid profile, prevention of excessive inflammation and immune dysfunction and a counter-action to the catabolic state.

Elevated Serum Insulin-Like Growth Factor 1 Levels in Patients with Neurological Remission after Traumatic Spinal Cord Injury

After traumatic spinal cord injury, an acute phase triggered by trauma is followed by a subacute phase involving inflammatory processes. We previously demonstrated that peripheral serum cytokine expression changes depend on neurological outcome after spinal cord injury. In a subsequent intermediate phase, repair and remodeling takes place under the mediation of growth factors such as Insulin-like Growth Factor 1 (IGF-1). IGF-1 is a promising growth factor which is thought to act as a neuroprotective agent. Since previous findings were taken from animal studies, our aim was to investigate this hypothesis in humans based on peripheral blood serum. Forty-five patients after traumatic spinal cord injury were investigated over a period of three months after trauma. Blood samples were taken according to a fixed schema and IGF-1 levels were determined. Clinical data including AIS scores at admission to the hospital and at discharge were collected and compared with IGF-1 levels. In our study, we could observe distinct patterns in the expression of IGF-1 in peripheral blood serum after traumatic spinal cord injury regardless of the degree of plegia. All patients showed a marked increase of levels seven days after injury. IGF-1 serum levels were significantly different from initial measurements at four and nine hours and seven and 14 days after injury, as well as one, two and three months after injury. We did not detect a significant correlation between fracture and the IGF-1 serum level nor between the quantity of operations performed after trauma and the IGF-1 serum level. Patients with clinically documented neurological remission showed consistently higher IGF-1 levels than patients without neurological remission. This data could be the base for the establishment of animal models for further and much needed research in the field of spinal cord injury.

Glucagon orchestrates stress-induced hyperglycaemia

Hyperglycaemia is commonly observed on admission and during hospitalization for medical illness, traumatic injury, burn and surgical intervention. This transient hyperglycaemia is referred to as stress-induced hyperglycaemia (SIH) and frequently occurs in individuals without a history of diabetes. SIH has many of the same underlying hormonal disturbances as diabetes mellitus, specifically absolute or relative insulin deficiency and glucagon excess. SIH has the added features of elevated blood levels of catecholamines and cortisol, which are not typically present in people with diabetes who are not acutely ill. The seriousness of SIH is highlighted by its greater morbidity and mortality rates compared with those of hospitalized patients with normal glucose levels, and this increased risk is particularly high in those without pre-existing diabetes. Insulin is the treatment standard for SIH, but new therapies that reduce glucose variability and hypoglycaemia are desired. In the present review, we focus on the key role of glucagon in SIH and discuss the potential use of glucagon receptor blockers and glucagon-like peptide-1 receptor agonists in SIH to achieve target glucose control.

A C-Peptide-Based Model of Pancreatic Insulin Secretion in Extremely Preterm Neonates in Intensive Care

BACKGROUND

Model-based glycemic control relies on sufficiency of underlying models to describe underlying patient physiology. In particular, very preterm infant glucose-insulin metabolism can differ significantly from adults, and is relatively unstudied. In this study, C-peptide concentrations are used to develop insulin-secretion models for the purposes of glycemic control in neonatal intensive care.

METHODS

Plasma C-peptide, insulin, and blood glucose concentrations (BGC) were retrospectively analyzed from a cohort of 41 hyperglycemic very preterm (median age 27.2 [26.2-28.7] weeks) and very low birth-weight infants (median birth weight 839 [735-1000] g). A 2-compartment model of C-peptide kinetics was used to estimate insulin secretion. Insulin secretion was examined with respect to nutritional intake, exogenous and plasma insulin concentration, and BGC.

RESULTS

Insulin secretion was found to be highly variable between patients and over time, and could not be modeled with respect to age, weight, or protein or dextrose intake. In 13 of 54 samples exogenous insulin was being administered, and insulin secretion was lower. However, low data numbers make this result inconclusive. Insulin secretion was found to increase with BG, with a stronger association in female infants than males (R(2) = .51 vs R(2) = .13, and R(2) = .26 for the combined cohort).

CONCLUSIONS

A sex-based insulin secretion model was created and incorporated into a model-based glycemic control framework. Nutritional intake did not predict insulin secretion, indicating that insulin secretion is a complex function of a number of metabolic factors.

Resuscitation volume in paediatric non-haemorrhagic blunt trauma

INTRODUCTION

Trauma is a major cause of paediatric morbidity and mortality, yet knowledge of fluid resuscitation is limited. Our objectives were to determine current practises in resuscitation volume (RV) administered to paediatric non-haemorrhagic (NH) blunt trauma patients and to identify fluid related complications.

METHODS

We examined data from 139 trauma patients 1-17 years of age with an injury severity score ≥ 12 resuscitated at a Trauma-designated Children's Hospital. Patients were separated into discreet groups based on ATLS age-dependent vital functions: toddler/preschooler (1-5 years), school age (6-12 years) and adolescent (13-17 years).

RESULTS

The median RV (total fluid intake-maintenance fluid intake) in ml/kg over the first 24h from the time of trauma by age was: 24 (IQR=19-47; 1-5 years); 26 (IQR=15-36; 6-12 years); and 22 (IQR=14-42; 13-17 years). The differences in RV/kg/24h following NH trauma was not significantly different between age groups (p=0.41). Urine output over the 24h ranged from 2.5 (IQR=1.9-3.3; lower age group) to 1.8 (IQR=1.2-2.4; upper age group) ml/kg/h; greater than the ATLS recommended age-dependent targets. Haematocrit was the only significant independent predictor of RV/kg/24h (p<0.001). Fluid-related complications attributable to RV were identified in 12% (n=17/139) of patients, and included ascites (8%; n=11/139) and/or pleural effusion(s) (9%; n=13/139). Patients with fluid-related complications received significantly more RV in ml/kg/24h (42, IQR=27-76) than those without complications (22, IQR=14-36; p=0.001).

CONCLUSIONS

The range of median RV administered to paediatric NH blunt trauma patients with ISS ≥ 12 was 22-26 ml/kg/24h. The RV administered was excessive based on high urine outputs and the presence of fluid-related complications. Further evaluation of RV triggers and endpoints used by paediatric traumatologists is required.

Impact of glucocorticoids on insulin resistance in the critically ill

Glucocorticoids (GCs) have been shown to reduce insulin sensitivity in healthy individuals. Widely used in critical care to treat a variety of inflammatory and allergic disorders, they may inadvertently exacerbate stress-hyperglycaemia. This research uses model-based methods to quantify the reduction in insulin sensitivity from GCs in critically ill patients, and thus their impact on glycaemic control. A model-based measure of insulin sensitivity (S(I)) was used to quantify changes between two matched cohorts of 40 intensive care unit (ICU) patients. Patients in one cohort received GC treatment, while patients in the control cohort did not. All patients were admitted to the Christchurch hospital ICU between 2005 and 2007 and spent at least 24h on the SPRINT glycaemic control protocol. A 31% reduction in whole-cohort median insulin sensitivity was seen between the control cohort and patients receiving glucocorticoids with a median dose equivalent to 200mg/d of hydrocortisone per patient. Comparing percentile patients as a surrogate for matched patients, reductions in median insulin sensitivity of 20%, 25%, and 21% were observed for the 25th-, 50th- and 75th-percentile patients, respectively. These cohort and percentile patient reductions are less than or equivalent to the 30-62% reductions reported in healthy subjects especially when considering the fact that the GC doses in this study are 1.3-4.0 times larger than those in studies of healthy subjects. This reduced suppression of insulin sensitivity in critically ill patients could be a result of saturation due to already increased levels of catecholamines and cortisol common in critically illness. Virtual trial simulation showed that reductions in insulin sensitivity of 20-30% associated with glucocorticoid treatment in the ICU have limited impact on glycaemic control levels within the context of the SPRINT protocol.

The integration of lipid-sensing and anti-inflammatory effects: how the PPARs play a role in metabolic balance

The peroxisomal proliferating-activated receptors (PPARs) are lipid-sensing transcription factors that have a role in embryonic development, but are primarily known for modulating energy metabolism, lipid storage, and transport, as well as inflammation and wound healing. Currently, there is no consensus as to the overall combined function of PPARs and why they evolved. We hypothesize that the PPARs had to evolve to integrate lipid storage and burning with the ability to reduce oxidative stress, as energy storage is essential for survival and resistance to injury/infection, but the latter increases oxidative stress and may reduce median survival (functional longevity). In a sense, PPARs may be an evolutionary solution to something we call the 'hypoxia-lipid' conundrum, where the ability to store and burn fat is essential for survival, but is a 'double-edged sword', as fats are potentially highly toxic. Ways in which PPARs may reduce oxidative stress involve modulation of mitochondrial uncoupling protein (UCP) expression (thus reducing reactive oxygen species, ROS), optimising forkhead box class O factor (FOXO) activity (by improving whole body insulin sensitivity) and suppressing NFkB (at the transcriptional level). In light of this, we therefore postulate that inflammation-induced PPAR downregulation engenders many of the signs and symptoms of the metabolic syndrome, which shares many features with the acute phase response (APR) and is the opposite of the phenotype associated with calorie restriction and high FOXO activity. In genetically susceptible individuals (displaying the naturally mildly insulin resistant 'thrifty genotype'), suboptimal PPAR activity may follow an exaggerated but natural adipose tissue-related inflammatory signal induced by excessive calories and reduced physical activity, which normally couples energy storage with the ability to mount an immune response. This is further worsened when pancreatic decompensation occurs, resulting in gluco-oxidative stress and lipotoxicity, increased inflammatory insulin resistance and oxidative stress. Reactivating PPARs may restore a metabolic balance and help to adapt the phenotype to a modern lifestyle.

Relationship Between Release of β-Endorphin, Cortisol, and Trauma Severity in Children With Blunt Torso and Extremity Trauma

PURPOSE

To determine the levels of beta-endorphin and cortisol in children with multiple injuries and to determine whether there is any difference between and compare the severity of trauma and beta-endorphin and cortisol release as calculated using Pediatric Trauma Score (PTS).

METHODS

During a 10-month period, 80 children with multiple injuries admitted to a University Hospital's Pediatric Surgery Department were studied. Blood samples were obtained immediately at admission and a PTS of each patient was calculated. The correlation between PTS and hormonal values were searched. The children were classified into two groups according to their PTS. Group 1 had PTS >8 and group 2 had PTS < or =8. The two groups were also compared with respect to their beta-endorphin and cortisol values.

RESULTS

There was a linear correlation between beta-endorphin and cortisol values and the injury severity. The levels were higher in the patients with more severe injuries. There were 60 patients in group 1 and 20 patients in group 2. Their ages were 9.2 +/- 4.1 and 9.7 +/- 4.2 years, respectively (p > 0.05). The mean PTS for group 1 patients was 11 +/- 0.8 and for group 2 patients was 7.4 +/- 1.2 (p < 0.001). The mean plasma beta-endorphin concentrations were 124.4 +/- 114.4 pg/mL in group 1 patients and 261.6 +/- 231.2 pg/mL in group 2 (p < 0.001). The respective plasma cortisol concentrations in the two groups were 22.5 +/- 10.3 microg/dL and 30.8 +/- 17.2 microg/dL (p < 0.05), respectively.

CONCLUSIONS

The results of this study show that the plasma beta-endorphin and cortisol levels are elevated in children after blunt trauma and the degree of elevation is related to the injury severity.

Interplay of stress and physical inactivity on muscle loss: Nutritional countermeasures

Inactivity-mediated protein catabolism occurs in many circumstances ranging from catastrophic events such as severe illness or injury, to unique environments such as spaceflight/microgravity, to more insidious causes such as physical frailty and the progression of aging. Nevertheless, regardless of the etiology, the consequences of inactivity are readily observable and debilitating. Mechanistically, the loss of lean body mass during inactivity is the result of a chronic imbalance between muscle protein synthesis and breakdown. When inactivity is accompanied by the stress of trauma or disease, the rate of muscle protein catabolism can increase several fold. Bed rest studies in healthy volunteers provide a unique opportunity to examine the mechanisms contributing to muscle loss and evaluate strategies for intervention that may slow muscle catabolism and promote anabolism. The prerequisite for muscle protein synthesis and the most readily adaptable stimulus is dietary-derived amino acids. This review focuses on the role of amino acid supplementation in the maintenance of skeletal muscle mass during age-related and clinically mandated inactivity.

Bed rest and myopathies

PURPOSE OF REVIEW

The loss of skeletal muscle with injury or critical illness can be dramatic. This review emphasizes the importance of skeletal muscle as a metabolic reserve. Changes in protein metabolism with bed rest alone and during physiological stress are discussed. Nutritional and hormonal interventions that ameliorate the loss of skeletal muscle are highlighted.

RECENT FINDINGS

The loss of skeletal muscle that occurs with inactivity alone can be prevented by nutritional supplementation with an essential amino acid formula. Bed rest with accompanying hypercortisolemia produces a threefold greater loss of skeletal muscle than bed rest alone. Essential amino acids stimulate muscle anabolism during acute hypercortisolemia; however, their effects during chronic hypercortisolemia must be explored.

SUMMARY

Skeletal muscle loss with trauma or critical illness is due in great part to the interaction of bed rest (muscular inactivity) and stress (hypercortisolemia). Younger individuals respond to nutritional and pharmacological interventions during bed rest alone. Given a lower relative lean mass in the elderly and the importance of skeletal muscle as a metabolic reserve during stress, it is understandable that clinical outcomes are worse in older patients. Countermeasures to the loss of skeletal muscle, especially in the stressed patient, must be developed.

Defective glucose homeostasis during infection

Infection leads to profound alterations in whole-body metabolism, which is characterized by marked acceleration of glucose, fat and protein, and amino acid flux. One of the complications of infection, especially in the nutritionally supported setting, is hyperglycemia. The hyperglycemia is caused by peripheral insulin resistance and alterations in hepatic glucose metabolism. The defects in hepatic glucose metabolism include overproduction of glucose and a failure of the liver to appropriately adapt when nutritional support is administered. Investigators have suggested that multiple factors contribute to the observed defects. In this review, I focus primarily on alterations in carbohydrate metabolism, examining both the metabolic response to infection and inflammatory stress, the role of the accompanying neuroendocrine and inflammatory responses in the metabolic response, and the interaction between the endocrine response to infection and nutritional support.

Amino acid supplementation for reversing bed rest and steroid myopathies

Muscular inactivity is inherent in many circumstances, including convalescence from serious illness or injury, spaceflight, and the progression of aging. Inactivity in a healthy individual leads to a decrease in whole-body protein turnover composed primarily of a decrease in muscle protein synthesis. The decrease in muscle protein synthesis leads to a substantial loss of lean body mass. We have demonstrated that this loss of lean mass is greater when inactivity is accompanied by stress, specifically hypercortisolemia. During convalescence from trauma or injury, the anabolic stimulus provided by nutrient ingestion represents a primary means of ameliorating the loss of muscle protein. We have previously demonstrated that ingestion of essential amino acids (EAAs), formulated to mimic the proportion of EAAs in muscle, provides a potent anabolic stimulus for muscle protein. Recently, we demonstrated that EAA supplementation throughout 28 d of bed rest stimulated net muscle protein synthesis. The repeated stimulation translated to maintenance of lean body mass and an amelioration of functional decrement compared to a placebo treatment. We have also demonstrated that this EAA supplement stimulates net protein synthesis during acute hypercortisolemia and are currently testing the effects during prolonged inactivity. Although EAAs promote muscle anabolism during hypercortisolemia, it is unlikely that a nutritional intervention alone would be effective in maintaining lean body mass during severe stress. It may be necessary to concomitantly reduce the catabolic influence of cortisol or provide another anabolic stimulus.

Relationship of Early Hyperglycemia to Mortality in Trauma Patients

INTRODUCTION

Recent randomized prospective data suggest that early hyperglycemia is associated with excess mortality in critically ill patients, and tight glucose control leads to improved outcome. This concept has not been carefully examined in trauma patients, and the relationship of early hyperglycemia to mortality from sepsis in this population is unclear. The objective of this study was to determine the relationship different levels of early blood glucose elevation to outcome in a trauma ICU population.

METHODS

The records of all patients admitted to the ICU over a 2-year period at a Level I trauma center were reviewed for age, injury severity scores (ISS), admission Glasgow Coma Scale (GCS) score, base deficit (BD), blood glucose, and mortality. Three possible cutoffs in defining hyperglycemia were examined (glucose > or =110 mg/dL, > or =150 mg/dL, > or =200 mg/dL) in relation to infection and mortality. Early hyperglycemia was defined as elevated blood glucose on hospital days 1 or 2. Those with diabetes mellitus were excluded.

RESULTS

From 1/00-12/01, 516 eligible patients were admitted to the ICU after injury. Early hyperglycemia occurred in 483 at the > or =110 mg/dL level, 311 at the > or =150 mg/dL level, and 90 patients at the > or =200 mg/dL level. Univariate logistic regression demonstrated a significant relationship between ISS and subsequent infection(p = 0.02) and a trend toward such a relationship in GCS score, glucose > or =150 mg/dL, and glucose > or =200 mg/dL (p = 0.06, 0.12, and 0.06). A similar analysis for the relationship of these variables to eventual mortality showed a significant correlation with all examined variables except glucose > or =110 mg/dL. Multiple logistic regression to control for the effect of age, ISS, GCS score, and BD found early glucose > or =200 mg/dL to be an independent predictor of both infection and mortality while no such relationship was found with > or = 110 mg/dL or > or =150 mg/dL.

CONCLUSIONS

Early hyperglycemia as defined by glucose > or =200 mg/dL is associated with significantly higher infection and mortality rates in trauma patients independent of injury characteristics. This was not true at the cutoffs of > or =110 mg/dL or > or =150 mg/dL. These data support the need for a prospective analysis of tight glucose control, keeping serum glucose <200 mg/dL in critically ill trauma patients. However, aggressive maintenance of levels <110 mg/dL as reported by others may not be necessary.

Hypercortisolemia alters muscle protein anabolism following ingestion of essential amino acids

Debilitating injury is accompanied by hypercortisolemia, muscle wasting, and disruption of the normal anabolic response to food. We sought to determine whether acute hypercortisolemia alters muscle protein metabolism following ingestion of a potent anabolic stimulus: essential amino acids (EAA). A 27-h infusion (80 microg. kg(-1). h(-1)) of hydrocortisone sodium succinate mimicked cortisol (C) levels accompanying severe injury (>30 microg/dl), (C + AA; n = 6). The control group (AA) received intravenous saline (n = 6). Femoral arteriovenous blood samples and muscle biopsies were obtained during a primed (2.0 micromol/kg) constant infusion (0.05 micromol. kg(-1). min(-1)) of l-[ring-(2)H(5)]phenylalanine before and after ingestion of 15 g of EAA. Hypercortisolemia [36.5 +/- 2.1 (C + AA) vs. 9.0 +/- 1.0 microg/dl (AA)] increased postabsorptive arterial, venous, and muscle intracellular phenylalanine concentrations. Hypercortisolemia also increased postabsorptive and post-EAA insulin concentrations. Net protein balance was blunted (40% lower) following EAA ingestion but remained positive for a greater period of time (60 vs. 180 min) in the C + AA group. Thus, although differences in protein metabolism were evident, EAA ingestion improved muscle protein anabolism during acute hypercortisolemia and may help minimize muscle loss following debilitating injury.

From Cuthbertson to fast-track surgery: 70 years of progress in reducing stress in surgical patients

OBJECTIVE

To evaluate the evolution of knowledge concerning the stress response in surgical patients and to determine the therapeutic benefit of stress reduction therapy.

SUMMARY BACKGROUND DATA

The stress response in surgical patients is associated with tissue catabolism, organ failure, and prolonged recovery. Understanding the neural-hormonal basis for these events has stimulated efforts to attenuate these undesirable effects. A review of the results of these efforts is important for the application of stress reduction therapy and further improvement of surgical care.

METHODS

Medline was searched from 1980 to the present using the terms "stress response," "neural-hormonal response," "fast track surgery," and "outcome in surgical patients." These papers were reviewed along with historical information relating to early descriptions of metabolic and stress responses in surgical patients.

RESULTS

Improved understanding of the stress response in surgical patients has occurred over the past 70 years. Multiple examples of stress reduction associated with decreased morbidity and mortality are reported.

CONCLUSIONS

Reduction of stress in surgical patients has improved outcome. The use of stress reduction techniques will continue to expand and contribute to the improvement of future surgical care.

From Cuthbertson to fast-track surgery: 70 years of progress in reducing stress in surgical patients

OBJECTIVE

To evaluate the evolution of knowledge concerning the stress response in surgical patients and to determine the therapeutic benefit of stress reduction therapy.

SUMMARY BACKGROUND DATA

The stress response in surgical patients is associated with tissue catabolism, organ failure, and prolonged recovery. Understanding the neural-hormonal basis for these events has stimulated efforts to attenuate these undesirable effects. A review of the results of these efforts is important for the application of stress reduction therapy and further improvement of surgical care.

METHODS

Medline was searched from 1980 to the present using the terms "stress response," "neural-hormonal response," "fast track surgery," and "outcome in surgical patients." These papers were reviewed along with historical information relating to early descriptions of metabolic and stress responses in surgical patients.

RESULTS

Improved understanding of the stress response in surgical patients has occurred over the past 70 years. Multiple examples of stress reduction associated with decreased morbidity and mortality are reported.

CONCLUSIONS

Reduction of stress in surgical patients has improved outcome. The use of stress reduction techniques will continue to expand and contribute to the improvement of future surgical care.

The effect of glutamine supplementation in patients following elective surgery and accidental injury

The metabolic response to injury, whether a controlled elective surgical procedure or an accidental injury, is characterized by the breakdown of skeletal muscle protein and the translocation of the amino acids to visceral organs and the wound. At these sites, the substrate serves to enhance host defenses, and support vital organ function and wound repair. Glutamine (GLN) plays a major role in these processes, accounting for approximately one third of the translocated nitrogen. From available data, GLN-supplemented intravenous nutrition in patients undergoing elective surgery improves nitrogen balance, helps correct the decreased GLN concentration found in the free intracellular skeletal muscle amino acid pool and enhances net protein synthesis (particularly in skeletal muscle). Six randomized blind trials (two multicentered investigations) reported a decreased length in hospital stay in postoperative patients receiving GLN supplementation. After blunt trauma, GLN supplementation increased plasma concentrations, attenuated the immunosuppression commonly observed and decreased the rate of infection. Patients with burn injury have low GLN plasma and intramuscular concentrations; turnover and synthesis rate are accelerated, yet apparently inadequate to support normal concentrations. These data suggest that GLN supplementation has important effects in catabolic surgical patients, but the exact mechanisms to explain these events remain unknown, and more research is required to explain the apparent benefits of dietary GLN.

Glutamate-containing parenteral nutrition doubles plasma glutamate: a risk factor in neurosurgical patients with blood-brain barrier damage?

OBJECTIVES

Animal studies have shown that the elevation of plasma glutamate levels increase cerebral edema formation whenever the blood-brain barrier is disturbed. Therefore, changes in plasma glutamate levels as influenced by the administration of a glutamate-containing amino acid solution were investigated in neurosurgical patients.

DESIGN

Prospective, descriptive study.

SETTING

Eight-bed neurosurgical intensive care unit in a university hospital.

PATIENTS

Twenty-three neurosurgical patients requiring parenteral nutrition.

INTERVENTIONS

Parenteral nutrition was begun 24 hrs after craniotomy. Patients receiving a glutamate-containing amino acid solution (3.75 g/L glutamate) were compared with patients infused with a glutamate-free solution.

MEASUREMENTS AND MAIN RESULTS

Arterial plasma and urine amino acids were analyzed using high-performance liquid chromatography. Administration of a glutamate-containing solution doubled plasma glutamate levels in neurosurgical patients (from 53.3 +/- 9.8 microM [preinfusion] to 98.5 +/- 18.7 microM [after 4 hrs of infusion]; p < 0.001), whereas no elevation was seen when infusing a glutamate-free solution (from 52.3 +/- 7.3 [1 hr of infusion] to 53.6 +/- 6.4 microM [4 hrs of infusion]). Upon terminating the glutamate-containing infusion, arterial plasma glutamate levels decreased immediately (from 120 +/- 13.2 microM to 81.2 +/- 19.5 microM). Glutamate as infused in excess appears to exceed a renal threshold and is eliminated renally.

CONCLUSIONS

As shown in animal models, administration of a glutamate-containing amino acid solution significantly increased plasma glutamate levels. Because such an increase in plasma glutamate levels could aggravate cerebral edema formation, glutamate-containing amino acid solutions cannot be recommended for patients with a disturbed blood-brain barrier.

Nutrition in the intensive care unit

Nutritional support has become a routine part of the care of the critically ill patient. It is an adjunctive therapy, the main goal of which is to attenuate the development of malnutrition, yet the effectiveness of nutritional support is often thwarted by an underlying hostile metabolic milieu. This requires that these metabolic changes be taken into consideration when designing nutritional regimens for such patients. There is also a need to conduct large, multi-center studies to acquire more knowledge of the cost-benefit and cost effectiveness of nutritional support in the critically ill.

Metabolic response to severe injury

BACKGROUND

Severe injury is associated with a complex sequence of metabolic events. The accurate quantification of these changes and a developing understanding of their aetiology has been the product of much work by researchers over the past 60 years. An understanding of these phenomena is vital to the practising surgeon because of the plethora of new metabolic modulators threatening to become part of clinical practice.

METHODS

This review describes the clinical picture of the metabolic response to severe injury and then outlines modern understanding of the underlying processes.

RESULTS AND CONCLUSION

The need for further research before introduction of new technologies is emphasized.

Dose-dependent effect of octreotide on nitrogen retention and glucose homeostasis in response to endotoxemia in parenterally fed rats

OBJECTIVE

This study compared the effect of different doses of octreotide on glucose and protein homeostasis in rats receiving concomitant lipopolysaccharide and parenteral nutrition infusions.

METHODS

Sixty-six male Sprague Dawley rats (185 to 220 g) were randomized to receive parenteral nutrition only (PN), PN plus continuous infusion of Escherichia coli 026:B6 lipopolysaccharide at 6 mg/kg/day (LPS), PN plus LPS plus octreotide at 10 micrograms/kg/day (LPS + Oct 10), 100 micrograms/kg/day (LPS + Oct 100), or 1000 micrograms/kg/day (LPS + Oct 1000) for 48 hours. Prior to randomization all animals received isocaloric and isonitrogenous PN (170 kcal/kg/day as glucose and 1.1 g N/kg/day) and were kept nil per os except for water ad libitum. Nitrogen balance, urinary 3-methylhistidine/creatinine ratio, serum glucose concentration, and incidence of glycosuria were compared between groups. Serum urea nitrogen (SUN) changes were incorporated into the cumulative 48 hour nitrogen balance. ANOVA, Duncan's multiple range test, and Fisher's Exact Test were used for statistical analysis.

RESULTS

Nitrogen balance (mg/48 hours) was significantly lower in all four groups receiving LPS +/- Oct when compared to the control group receiving PN alone. SUN (mg/dL) was significantly higher in all four groups receiving LPS +/- Oct when compared to control. There were no statistically significant differences in nitrogen balance or SUN among the four groups receiving LPS +/- Oct. The ratio of urinary 3-methylhistidine/ creatinine was significantly higher in the LPS + Oct 1000 group compared to the PN group (0.77 +/- 0.37 vs. 0.42 +/- 0.24, p < 0.05). Serum glucose concentrations and incidence of glycosuria among the five groups were not significantly different.

CONCLUSIONS

Endotoxin significantly reduces nitrogen balance compared to controls fed PN. Octreotide does not significantly improve nitrogen retention or glucose homeostasis in endotoxemic parenterally fed rats.

Hormonal regulation of human muscle protein metabolism

A continuous turnover of protein (synthesis and breakdown) maintains the functional integrity and quality of skeletal muscle. Hormones are important regulators of this remodeling process. Anabolic hormones stimulate human muscle growth mainly by increasing protein synthesis (growth hormone, insulin-like growth factors, and testosterone) or by decreasing protein breakdown (insulin). Unlike in growing animals, insulin's main anabolic effect on muscle protein in adult humans is an inhibition of protein breakdown. Protein synthesis is stimulated only in the presence of a high amino acid supply. A combination of the stress hormones (glucagon, glucocorticoids, and catecholamines) cause muscle catabolism, but the effects of the individual hormones on human muscle and their mechanisms of action remain to be clearly defined. Although thyroid hormone is essential during growth, both an excess and a deficiency cause muscle wasting by yet unknown mechanisms. A greater understanding of the regulation of human muscle protein metabolism is essential to elucidate mechanisms of muscle wasting.

Prolonged bed rest decreases skeletal muscle and whole body protein synthesis

We sought to determine the extent to which the loss of lean body mass and nitrogen during inactivity was due to alterations in skeletal muscle protein metabolism. Six male subjects were studied during 7 days of diet stabilization and after 14 days of stimulated microgravity (-6 degrees bed rest). Nitrogen balance became more negative (P < 0.03) during the 2nd wk of bed rest. Leg and whole body lean mass decreased after bed rest (P < 0.05). Serum cortisol, insulin, insulin-like growth factor I, and testosterone values did not change. Arteriovenous model calculations based on the infusion of L-[ring-13C6]-phenylalanine in five subjects revealed a 50% decrease in muscle protein synthesis (PS; P < 0.03). Fractional PS by tracer incorporation into muscle protein also decreased by 46% (P < 0.05). The decrease in PS was related to a corresponding decrease in the sum of intracellular amino acid appearance from protein breakdown and inward transport. Whole body protein synthesis determined by [15N]alanine ingestion on six subjects also revealed a 14% decrease (P < 0.01). Neither model-derived nor whole body values for protein breakdown change significantly. These results indicate that the loss of body protein with inactivity is predominantly due to a decrease in muscle PS and that this decrease is reflected in both whole body and skeletal muscle measures.

NO2/NO3 and cytokine plasma profiles under different postoperative parenteral nutrition regimens

Both nitric oxide and cytokines are considered mediators of the acute-phase response in humans, and their early postoperative period plasma levels have been found to be of prognostic value. On the other hand, it has been suggested that the fatty emulsions used in total parenteral nutrition (TPN) may induce changes in macrophage function. In the present study we investigated the postoperative evolution of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), interleukin-6 (IL-6), and nitrate/nitrite plasma levels under three different TPN regimens. Twenty-one patients diagnosed with upper digestive tract neoplasm, without preoperative TPN, and having undergone radical surgery, were randomly assigned to three groups: Group I, all nonprotein calories supplied by hypertonic glucose solution: Group II, 55% of the nonprotein calories supplied by glucose and 45% by 20% long-chain triacylglycerides emulsion (LCT) (Intralipid 20%, Kabi-Pharmacia); Group III, same as Group II, but a 20% emulsion of a mixture of medium-chain and long-chain triacylglycerides (MCT/LCT) (Lipofundina MCT/LCT 20%, B. Braun) was used instead of LCT. Blood samples were obtained on postoperative Days 1-5 and 10, 3 h after ending the lipid infusion. In all the three groups IL-1, IL-6, and TNF-alpha levels rose after surgery, peaking at Day 2, whereas NO2/NO3 levels had their peak at Day 3. Day-to-day comparison of plasma levels of cytokines and NO2/NO3 between the investigated groups did not show any statistical significance. Differences between group means were not found when the areas under the curve over the first 5 postoperative days were compared (1.72 +/- 0.25, Group I; 1.88 +/- 0.34, Group II; and 2.52 +/- 0.50, Group III, for TNF-alpha; 1.79 +/- 0.12, Group I; 1.92 +/- 0.18, Group II; and 1.50 +/- 0.12, Group III, for NO2/NO3). We conclude that the different parenteral nutrition regimens studied do not evoke alterations in cytokine and NO2 + NO3 levels in the patient groups investigated in this study.