DNA methylation alterations in muscle of critically ill patients.

BACKGROUND: Intensive care unit (ICU)-acquired weakness can persist beyond ICU stay and has been associated with long-term functional impairment of ICU survivors. Recently, DNA methylation alterations were found in the blood of ICU patients, partially explaining long-term developmental impairment of critically ill children. As illness-induced aberrant DNA methylation theoretically could also be involved in long-term weakness, we investigated whether the DNA methylation signature in muscle of adult critically ill patients differs from that in muscle of healthy controls. METHODS: Genome-wide methylation was determined (Infinium® HumanMethylationEPIC BeadChips) in DNA extracted from skeletal muscle biopsies that had been collected on Day 8 ± 1 in ICU from 172 EPaNIC-trial patients [66% male sex, median age 62.7 years, median body mass index (BMI) 25.9 kg/m2 ] and 20 matched healthy controls (70% male sex, median age 58.0 years, median BMI 24.4 kg/m2 ). Methylation status of individual cytosine-phosphate-guanine (CpG) sites of patients and controls was compared with F-tests, using the Benjamini-Hochberg false discovery rate to correct for multiple comparisons. Differential methylation of DNA regions was assessed with bump hunting, with 1000 permutations assessing uncertainty, expressed as family-wise error rate. Gene expression was investigated for 10 representative affected genes. RESULTS: In DNA from ICU patients, 565 CpG sites, associated with 400 unique genes, were differentially methylated as compared with controls (average difference 3.2 ± 0.1% ranging up to 16.9%, P < 0.00005). Many of the associated genes appeared highly relevant for muscle structure and function/weakness, including genes involved in myogenesis, muscle regeneration, nerve/muscle membrane excitability, muscle denervation/re-innervation, axon guidance/myelination/degeneration/regeneration, synapse function, ion channelling with especially calcium signalling, metabolism (glucose, protein, and fat), insulin signalling, neuroendocrine hormone regulation, mitochondrial function, autophagy, apoptosis, oxidative stress, Wnt signalling, transcription regulation, muscle fat infiltration during regeneration, and fibrosis. In patients as compared with controls, we also identified two hypomethylated regions, spanning 18 and 3 CpG sites in the promoters of the HIC1 and NADK2 genes, respectively (average differences 5.8 ± 0.01% and 12.1 ± 0.04%, family-wise error rate <0.05). HIC1 and NADK2 play important roles in muscle regeneration and postsynaptic acetylcholine receptors and in mitochondrial processes, respectively. Nine of 10 investigated genes containing DNA methylation alterations were differentially expressed in patients as compared with controls (P ≤ 0.03). CONCLUSIONS: Critically ill patients present with a different DNA methylation signature in skeletal muscle as compared with healthy controls, which in theory could provide a biological basis for long-term persistence of weakness in ICU survivors. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00512122, registered on 31 July 2007.

Aerobic exercise capacity in long-term survivors of critical illness: secondary analysis of the post-EPaNIC follow-up study.

PURPOSE: To evaluate aerobic exercise capacity in 5-year intensive care unit (ICU) survivors and to assess the association between severity of organ failure in ICU and exercise capacity up to 5-year follow-up. METHODS: Secondary analysis of the EPaNIC follow-up cohort (NCT00512122) including 433 patients screened with cardiopulmonary exercise testing (CPET) between 1 and 5 years following ICU admission. Exercise capacity in 5-year ICU survivors (N = 361) was referenced to a historic sedentary population and further compared to demographically matched controls (N = 49). In 5-year ICU survivors performing a maximal CPET (respiratory exchange ratio > 1.05, N = 313), abnormal exercise capacity was defined as peak oxygen consumption (VO2peak) < 85% of predicted peak oxygen consumption (%predVO2peak), based on the historic sedentary population. Exercise liming factors were identified. To study the association between severity of organ failure, quantified as the maximal Sequential Organ Failure Assessment score during ICU-stay (SOFA-max), and exercise capacity as assessed with VO2peak, a linear mixed model was built, adjusting for predefined confounders and including all follow-up CPET studies. RESULTS: Exercise capacity was abnormal in 118/313 (37.7%) 5-year survivors versus 1/48 (2.1%) controls with a maximal CPET, p < 0.001. Aerobic exercise capacity was lower in 5-year survivors than in controls (VO2peak: 24.0 ± 9.7 ml/min/kg versus 31.7 ± 8.4 ml/min/kg, p < 0.001; %predVO2peak: 94% ± 31% versus 123% ± 25%, p < 0.001). Muscular limitation frequently contributed to impaired exercise capacity at 5-year [71/118 (60.2%)]. SOFA-max independently associated with VO2peak throughout follow-up. CONCLUSIONS: Critical illness survivors often display abnormal aerobic exercise capacity, frequently involving muscular limitation. Severity of organ failure throughout the ICU stay independently associates with these impairments.

Reduced nocturnal ACTH-driven cortisol secretion during critical illness.

Recently, during critical illness, cortisol metabolism was found to be reduced. We hypothesize that such reduced cortisol breakdown may suppress pulsatile ACTH and cortisol secretion via feedback inhibition. To test this hypothesis, nocturnal ACTH and cortisol secretory profiles were constructed by deconvolution analysis from plasma concentration time series in 40 matched critically ill patients and eight healthy controls, excluding diseases or drugs that affect the hypothalamic-pituitary-adrenal axis. Blood was sampled every 10 min between 2100 and 0600 to quantify plasma concentrations of ACTH and (free) cortisol. Approximate entropy, an estimation of process irregularity, cross-approximate entropy, a measure of ACTH-cortisol asynchrony, and ACTH-cortisol dose-response relationships were calculated. Total and free plasma cortisol concentrations were higher at all times in patients than in controls (all P < 0.04). Pulsatile cortisol secretion was 54% lower in patients than in controls (P = 0.005), explained by reduced cortisol burst mass (P = 0.03), whereas cortisol pulse frequency (P = 0.35) and nonpulsatile cortisol secretion (P = 0.80) were unaltered. Pulsatile ACTH secretion was 31% lower in patients than in controls (P = 0.03), again explained by a lower ACTH burst mass (P = 0.02), whereas ACTH pulse frequency (P = 0.50) and nonpulsatile ACTH secretion (P = 0.80) were unchanged. ACTH-cortisol dose response estimates were similar in patients and controls. ACTH and cortisol approximate entropy were higher in patients (P ≤ 0.03), as was ACTH-cortisol cross-approximate entropy (P ≤ 0.001). We conclude that hypercortisolism during critical illness coincided with suppressed pulsatile ACTH and cortisol secretion and a normal ACTH-cortisol dose response. Increased irregularity and asynchrony of the ACTH and cortisol time series supported non-ACTH-dependent mechanisms driving hypercortisolism during critical illness.

Amino acid concentrations in critically ill children following cardiac surgery*.

OBJECTIVE: Guidelines for administering amino acids to critically ill children are largely based on uncontrolled observational studies and expert opinion, without support from rigorous outcome studies. Also, data on circulating amino acid concentrations during critical illness are scarce. We thoroughly studied the time profiles of circulating amino acid concentrations in critically ill children who received standard nutritional care according to international guidelines. DESIGN: This is a subanalysis of pediatric critically ill patients included in a large (n = 700) randomized controlled study on intensive insulin therapy. SETTING: The study was conducted at a university hospital PICU. PATIENTS: We studied 100 patients in PICU for at least 3 days following cardiac surgery. INTERVENTIONS: Patients were assigned to intensive insulin therapy targeting normal-for-age fasting blood glucose concentrations or insulin infusion only to prevent excessive hyperglycemia. MEASUREMENTS AND MAIN RESULTS: Plasma amino acid concentrations were measured at admission, day 3, and day 7 in PICU. At admission, the concentrations of most amino acids were comparable to those reported for healthy children. Total amino acid concentrations remained stable during ICU stay, but individual amino acids showed different time profiles with eight of them showing an increase and five a decrease. Nonsurviving children had higher total amino acid concentrations and individual amino acids compared with survivors at admission and/or during ICU stay. Intensive insulin therapy lowered the concentrations of total amino acids and several individual amino acids. Neonates showed somewhat different amino acid profiles with rather increased concentrations from baseline with time in ICU for total amino acids and several individual amino acids as compared with older infants and children. CONCLUSIONS: Circulating amino acid concentrations in critically ill children after cardiac surgery differ according to survival status, blood glucose control with intensive insulin therapy, and age.

Lectin pathway of complement activation and relation with clinical complications in critically ill children.

BACKGROUND: Critically ill children are susceptible to nosocomial infections, which contribute to adverse outcomes. Deficiencies in the innate immunity lectin pathway of complement activation are implicated in a child's vulnerability to infections in conditions such as cancer, but the role during critical illness remains unclear. We hypothesized that low on-admission levels of the pathway proteins are, in part, genetically determined and associated with susceptibility to infectious complications and adverse outcomes. METHODS: We studied protein levels of mannose-binding lectin (MBL), H-ficolin and M-ficolin, three MBL-associated-serine proteases (MASPs) and MBL-associated protein (MAp44), and relation with functional genetic polymorphisms, in 130 healthy children and upon intensive care unit (ICU) admission in 700 critically ill children of a randomized study on glycemic control. RESULTS: Levels of MASP-1, MASP-2, MASP-3, and MAp-44 were lower and the levels of M-ficolin were higher in ICU patients on admission than those in matched healthy controls. Only a low on-admission MASP-3 level was independently associated with risk of new ICU infections and prolonged ICU stay, after correcting for other risk factors. On-admission MASP-3 varied with age, illness severity, and genetic variation. CONCLUSION: Low on-admission MASP-3 levels in critically ill children were independently associated with subsequent acquisition of infection and prolonged ICU stay. The biological explanation needs further investigation.

Reduced cortisol metabolism during critical illness.

BACKGROUND: Critical illness is often accompanied by hypercortisolemia, which has been attributed to stress-induced activation of the hypothalamic-pituitary-adrenal axis. However, low corticotropin levels have also been reported in critically ill patients, which may be due to reduced cortisol metabolism. METHODS: In a total of 158 patients in the intensive care unit and 64 matched controls, we tested five aspects of cortisol metabolism: daily levels of corticotropin and cortisol; plasma cortisol clearance, metabolism, and production during infusion of deuterium-labeled steroid hormones as tracers; plasma clearance of 100 mg of hydrocortisone; levels of urinary cortisol metabolites; and levels of messenger RNA and protein in liver and adipose tissue, to assess major cortisol-metabolizing enzymes. RESULTS: Total and free circulating cortisol levels were consistently higher in the patients than in controls, whereas corticotropin levels were lower (P<0.001 for both comparisons). Cortisol production was 83% higher in the patients (P=0.02). There was a reduction of more than 50% in cortisol clearance during tracer infusion and after the administration of 100 mg of hydrocortisone in the patients (P≤0.03 for both comparisons). All these factors accounted for an increase by a factor of 3.5 in plasma cortisol levels in the patients, as compared with controls (P<0.001). Impaired cortisol clearance also correlated with a lower cortisol response to corticotropin stimulation. Reduced cortisol metabolism was associated with reduced inactivation of cortisol in the liver and kidney, as suggested by urinary steroid ratios, tracer kinetics, and assessment of liver-biopsy samples (P≤0.004 for all comparisons). CONCLUSIONS: During critical illness, reduced cortisol breakdown, related to suppressed expression and activity of cortisol-metabolizing enzymes, contributed to hypercortisolemia and hence corticotropin suppression. The diagnostic and therapeutic implications for critically ill patients are unknown. (Funded by the Belgian Fund for Scientific Research and others; ClinicalTrials.gov numbers, NCT00512122 and NCT00115479; and Current Controlled Trials numbers, ISRCTN49433936, ISRCTN49306926, and ISRCTN08083905.).

Impact of early nutrient restriction during critical illness on the nonthyroidal illness syndrome and its relation with outcome: a randomized, controlled clinical study.

CONTEXT: Both critical illness and fasting induce low circulating thyroid hormone levels in the absence of a rise in TSH, a constellation-labeled nonthyroidal illness syndrome (NTI). The contribution of restricted nutrition during critical illness in the pathophysiology of NTI remains unclear. OBJECTIVE: The objective of the study was to investigate the impact of nutrient restriction early during critical illness on the NTI, in relation to outcome. DESIGN AND PATIENTS: A preplanned subanalysis in a group of intensive care unit (ICU) patients admitted after complicated surgery and for whom enteral nutrition was contraindicated (n = 280) of a randomized controlled trial, which compared tolerating pronounced nutritional deficit for 1 week in the ICU [late parenteral nutrition (PN)] with early initiation of parenteral nutrition (early PN). MEASUREMENTS: Circulating TSH, total T4, T3, rT3, and leptin levels were quantified upon admission and on ICU day 3 or the last day when patients were discharged earlier. After correction for baseline risk factors, the role of these changes from baseline in explaining the outcome benefit of late PN was assessed with the multivariable Cox proportional hazard analysis. RESULTS: Late PN reduced complications and accelerated recovery. Circulating levels of TSH, total T4, T3, the T3 to rT3 ratio, and leptin levels were all further reduced by late PN. The further lowering of T4 appeared to reduce the outcome benefit of late PN, whereas the further reduction of T3 to rT3 ratio appeared to statistically explain part of the outcome benefit. CONCLUSIONS: Tolerating nutrient restriction early during critical illness, shown to accelerate recovery, further aggravated the NTI. The statistical analyses suggested that the more pronounced peripheral inactivation of the thyroid hormone with nutrient restriction during critical illness could be a beneficial adaptation, whereas the lowering of T4 could be deleterious.

Effect of tolerating macronutrient deficit on the development of intensive-care unit acquired weakness: a subanalysis of the EPaNIC trial.

BACKGROUND: Patients who are critically ill can develop so-called intensive-care unit acquired weakness, which delays rehabilitation. Reduced muscle mass, quality, or both might have a role. The Early Parenteral Nutrition Completing Enteral Nutrition in Adult Critically Ill Patients (EPaNIC) trial (registered with ClinicalTrials.gov, number NCT00512122) showed that tolerating macronutrient deficit for 1 week in intensive-care units (late parenteral nutrition [PN]) accelerated recovery compared with early PN. The role of weakness was unclear. Our aim was to assess whether late PN and early PN differentially affect muscle weakness and autophagic quality control of myofibres. METHODS: In this prospectively planned subanalysis of the EPaNIC trial, weakness (MRC sum score) was assessed in 600 awake, cooperative patients. Skeletal muscle biopsies, harvested from 122 patients 8 days after randomisation and from 20 matched healthy controls, were studied for autophagy and atrophy. We determined the significance of differences with Mann-Whitney U, Median, Kruskal-Wallis, or χ(2) (exact) tests, as appropriate. FINDINGS: With late PN, 105 (34%) of 305 patients had weakness on first assessment (median day 9 post-randomisation) compared with 127 (43%) of 295 patients given early PN (absolute difference -9%, 95% CI -16 to -1; p=0·030). Weakness recovered faster with late PN than with early PN (p=0·021). Myofibre cross-sectional area was less and density was lower in critically ill patients than in healthy controls, similarly with early PN and late PN. The LC3 (microtubule-associated protein light chain 3) II to LC3I ratio, related to autophagosome formation, was higher in patients given late PN than early PN (p=0·026), reaching values almost double those in the healthy control group (p=0·0016), and coinciding with less ubiquitin staining (p=0·019). A higher LC3II to LC3I ratio was independently associated with less weakness (p=0·047). Expression of mRNA encoding contractile myofibrillary proteins was lower and E3-ligase expression higher in muscle biopsies from patients than in control participants (p≤0·0006), but was unaffected by nutrition. INTERPRETATION: Tolerating a substantial macronutrient deficit early during critical illness did not affect muscle wasting, but allowed more efficient activation of autophagic quality control of myofibres and reduced weakness. FUNDING: UZ Leuven, Research Foundation-Flanders, the Flemish Government, and the European Research Council.

Muscle atrophy and preferential loss of myosin in prolonged critically ill patients.

OBJECTIVE: Muscle weakness contributes to prolonged rehabilitation and adverse outcome of critically ill patients. Distinction between a neurogenic and/or myogenic underlying problem is difficult using routine diagnostic tools. Preferential loss of myosin has been suggested to point to a myogenic component. We evaluated markers of muscle atrophy and denervation, and the myosin/actin ratio in limb and abdominal wall skeletal muscle of prolonged critically ill patients and matched controls in relation to insulin therapy and known risk factors for intensive care unit-acquired weakness. DESIGN: Secondary analysis of two large, prospective, single-center randomized clinical studies. SETTING: University hospital surgical and medical intensive care unit. PATIENTS: Critically ill patients and matched controls. INTERVENTIONS: Intensive care unit patients had been randomized to blood glucose control to 80-110 mg/dL with insulin infusion or conventional glucose management, where insulin was only administered when glucose levels rose above 215 mg/dL. MEASUREMENTS AND MAIN RESULTS: As compared with controls, rectus abdominis and vastus lateralis muscle of critically ill patients showed smaller myofiber size, decreased mRNA levels for myofibrillar proteins, increased proteolytic enzyme activities, and a lower myosin/actin ratio, virtually irrespective of insulin therapy. Increased forkhead box O1 action may have played a role. Most alterations were more severe in patients treated with corticosteroids. Duration of corticosteroid treatment, independent of duration of intensive care unit stay or other risk factors, was a dominant risk factor for a low myosin/actin ratio. The immature acetylcholine receptor subunit γ messenger RNA expression was elevated in vastus lateralis, independent of the myosin/actin ratio. CONCLUSIONS: Both limb and abdominal wall skeletal muscles of prolonged critically ill patients showed downregulation of protein synthesis at the gene expression level as well as increased proteolysis. This affected myosin to a greater extent than actin, resulting in a decreased myosin/actin ratio. Muscle atrophy was not ameliorated by intensive insulin therapy, but possibly aggravated by corticosteroids.

Mitochondrial fusion, fission, and biogenesis in prolonged critically ill patients.

CONTEXT: Critical illness induces swelling, enlargement, and dysfunction of mitochondria, which in liver, but not in muscle, is aggravated by excessive hyperglycemia. We previously demonstrated impaired autophagic clearance of damaged mitochondria in fed prolonged critically ill patients. Impaired fusion/fission-mediated repair and/or renewal through biogenesis may further accentuate mitochondrial abnormalities. OBJECTIVE: We studied mitochondrial fusion/fission and biogenesis and how these are affected by preventing hyperglycemia with insulin during critical illness. DESIGN AND SETTING: Patients admitted to a university hospital surgical/medical intensive-care unit participated in a randomized study. PATIENTS: We studied adult prolonged critically ill patients vs. controls. INTERVENTION: Tolerating hyperglycemia up to 215 mg/dl was compared with intensive insulin therapy targeting normoglycemia (80-110 mg/dl). MAIN OUTCOME MEASURES: In liver and skeletal muscle, we quantified levels of several proteins involved in mitochondrial fusion/fission and biogenesis. RESULTS: Key players in mitochondrial fusion/fission and biogenesis were up-regulated in postmortem liver (1.4- to 3.7-fold) and rectus abdominis (1.2- to 4.2-fold) but not in in vivo or postmortem vastus lateralis biopsies of critically ill patients. Maintaining normoglycemia with insulin attenuated the hepatic response in the mitochondrial fusion/fission process but did not affect the markers of mitochondrial biogenesis in liver or muscle. CONCLUSIONS: Our observations suggest tissue-dependent attempts of compensatory activation of mitochondrial repair mechanisms during critical illness. Considering the previously observed persistent mitochondrial damage, this activation may be insufficient and contribute to mitochondrial dysfunction. Suppressed activation of fusion/fission when excessive hyperglycemia is prevented with insulin may reflect reduced need for diluting (less) damage during normoglycemia or, alternatively, a suppressive effect of insulin on repair.

Serial lactate measurements using microdialysis of interstitial fluid do not correlate with plasma lactate in children after cardiac surgery.

OBJECTIVES: Serial postoperative blood lactate (BL) concentrations have been shown to predict outcome of children after congenital heart surgery (CHS), and interventions aimed at lowering lactate can improve the outcome of these children. The cumulative blood loss for diagnostic purposes, such as repetitive arterial blood sampling in the intensive care unit, contributes, especially in small children, to anemia. Techniques to limit blood loss can therefore be of use. Microdialysis is a technique to monitor tissue chemistry in various clinical settings, and we hypothesized that it may be a valuable alternative for frequent blood sampling to monitor lactate in children after CHS. METHODS: Fifteen children with a mean age of 40 months (range, 4-118 months) were prospectively enrolled after CHS. A CMA double lumen microdialysis catheter was inserted into the subcutaneous adipose tissue of the abdominal wall and infused with an isotone mannitol 5% solution at 1 microL/min via the inlet tubing. Microdialysate fluid was collected every hour for 48 hrs and stored at -80 degrees C for lactate determination (interstitial fluid lactate, IFL). Every hour arterial blood was taken for lactate determination. Individual profiles, correlation coefficient, and Bland-Altman analysis were used to compare BL and IFL results. RESULTS: There were no complications with the microdialysis technique. All patients were discharged alive from hospital. Six hundred twenty paired samples were analyzed. Mean recovery of microdialysate fluid was 84%. Median (interquartile range) was 0.95 (0.70-1.15) mmol/L for BL and 1.13 (0.86-1.48) mmol/L for IFL (p < 0.0001). Individual profiles showed that IFL follows changes in BL in some, but not all children. With this study, we could not explain this discrepancy. The correlation between BL and IFL was poor (r = .77 (p < 0.0001) r = .59). Bland-Altman analysis confirmed the insufficient performance of the current microdialysis-based procedure compared with BL. CONCLUSION: Serial lactate measurements in microdialysis fluid of subcutaneous adipose tissue are feasible, but cannot be used as a reliable interchangeable method for plasma lactate analysis in children after CHS at this time. Whether this technique has its own place in the assessment of the overall hemodynamic status and tissue perfusion in children after CHS needs to be addressed in future studies.

Strict blood glucose control with insulin during intensive care after cardiac surgery: impact on 4-years survival, dependency on medical care, and quality-of-life.

AIMS: To document the impact of intensive insulin therapy during intensive care on long-term (4 years) outcome of high-risk cardiac surgery patients. METHODS AND RESULTS: In this pre-planned sub-analysis and follow-up study of a large, randomized controlled trial on the effects of intensive insulin therapy during critical illness, we assessed long-term outcome in the 970 patients who had been admitted after high-risk cardiac surgery (mean+/-SD EuroSCORE of 6.0+/-3.7; EuroSCORE-predicted hospital mortality of 9.9%; observed hospital mortality of 7.5% in the conventional insulin group and 3.4% in the intensive insulin group). Long-term outcome was quantified as: (a) 4 years survival; (b) incidence of hospital re-admission; (c) level of activity and medical care requirements at 4 years as assessed by the Karnofsky score; and (d) perceived health-related quality-of-life at 4 years as assessed by the Nottingham Health Profile. Four years after ICU admission, the number of post-hospital discharge deaths was similar in the two study groups, reflecting maintenance of the acute survival benefit with intensive insulin therapy. Survivors who had been treated with intensive insulin during ICU stay revealed a similar risk for hospital re-admission and a comparable level of dependency on medical care. There was no effect on quality-of-life in the total group, whereas the increased survival of sicker patients with at least 3 days of insulin therapy evoked a more compromised perceived quality-of-life, in particular regarding social and family life. CONCLUSION: The short-term survival benefit obtained with insulin-titrated glycaemic control during intensive care after cardiac surgery was maintained after 4 years, without inducing increased medical care requirements but possibly at the expense of compromised perceived quality of social and family life.

Serum 3,3',5'-triiodothyronine (rT3) and 3,5,3'-triiodothyronine/rT3 are prognostic markers in critically ill patients and are associated with postmortem tissue deiodinase activities.

INTRODUCTION AND METHODS: Critical illness is associated with reduced TSH and thyroid hormone secretion, and with changes in peripheral thyroid hormone metabolism, resulting in low serum T3 and high rT3. In 451 critically ill patients who received intensive care for more than 5 d, serum thyroid parameters were determined on d 1, 5, 15, and last day (LD). All patients had been randomized for intensive or conventional insulin treatment. Seventy-one patients died, and postmortem liver and skeletal muscle biopsies were obtained from 50 of them for analysis of deiodinase (D1-3) activities. RESULTS: Insulin treatment did not affect thyroid parameters. On d 1, rT3 was higher and T3/rT3 was lower in nonsurvivors as compared with survivors (P = 0.001). Odds ratio for survival of the highest vs. the lowest quartile was 0.3 for rT3 and 2.9 for T3/rT3. TSH, T4, and T3 were lower in nonsurvivors from d 5 until LD (P < 0.001). TSH, T4, T3, and T3/rT3 increased over time in survivors, but decreased or remained unaltered in nonsurvivors. Liver D1 activity was positively correlated with LD serum T3/rT3 (R = 0.83, P < 0.001) and negatively correlated with rT3 (R = -0.69, P < 0.001). Both liver and skeletal muscle D3 activity were positively correlated with LD serum rT3 (R = 0.32, P = 0.02 and R = 0.31, P = 0.03). CONCLUSION: In critically ill patients who required more than 5 d of intensive care, rT3 and T3/rT3 were already prognostic for survival on d 1. On d 5, T4, T3, but also TSH levels are higher in patients who will survive. Serum rT3 and T3/rT3 were correlated with postmortem tissue deiodinase activities.

Modulation of asymmetric dimethylarginine in critically ill patients receiving intensive insulin treatment: a possible explanation of reduced morbidity and mortality?

OBJECTIVE: Asymmetric dimethylarginine, which inhibits production of nitric oxide, has been shown to be a strong and independent predictor of mortality in critically ill patients with clinical evidence of organ dysfunction. Interestingly, intensive insulin therapy in critically ill patients improved morbidity and mortality, but the exact mechanisms by which these beneficial effects are brought about remain unknown. Therefore, we aimed to investigate whether modulation of asymmetric dimethylarginine concentrations by intensive insulin therapy is involved in these effects. DESIGN: A prospective, randomized, controlled trial. SETTING: A 56-bed predominantly surgical intensive care unit in a tertiary teaching hospital. PATIENTS: From a study of 1,548 critically ill patients who were randomized to receive either conventional or intensive insulin therapy, we included 79 patients who were admitted to the intensive care unit after complicated pulmonary and esophageal surgery and required prolonged (>/=7 days) intensive care. INTERVENTIONS: Determination of asymmetric dimethylarginine concentrations. MEASUREMENTS AND MAIN RESULTS: Asymmetric dimethylarginine concentrations were determined with high-performance liquid chromatography on the day of admission, on day 2, on day 7, and on the last day at the intensive care unit. Although the asymmetric dimethylarginine levels did not change between day 0 and day 2 in patients receiving intensive insulin treatment, there was a significant increase during this period in the conventionally treated patients (p = .043). Interestingly, the mean daily insulin dose was inversely associated with the asymmetric dimethylarginine concentration on the last day (r = -.23, p = .042), and the asymmetric dimethylarginine concentration on the last day at the intensive care unit was significantly lower in the intensive insulin treatment group (p = .048). Furthermore, asymmetric dimethylarginine was positively associated with duration of intensive care unit stay, duration of ventilatory support, duration of inotropic and vasopressor treatment, number of red cell transfusions, duration of antibiotic treatment, presence of critical illness polyneuropathy, mean Acute Physiology and Chronic Health Evaluation II score, and cumulative Therapeutic Intervention Scoring System-28 score. In addition, asymmetric dimethylarginine levels in patients who died were significantly higher compared with survivors, and changes in the course of asymmetric dimethylarginine plasma concentrations were predictive for adverse intensive care unit outcome. CONCLUSIONS: Modulation of asymmetric dimethylarginine concentration by insulin at least partly explains the beneficial effects found in critically ill patients receiving intensive insulin therapy.

Bone turnover in prolonged critical illness: effect of vitamin D.

In prolonged critical illness, increased bone resorption and osteoblast dysfunction have been reported facing low 25 hydroxy vitamin D [25(OH)D] concentrations. The current study investigates the extent to which lack of nutritional vitamin D and time in intensive care contribute to bone loss in the critically ill. Prolonged critically ill patients (n = 22) were compared with matched controls and then randomized to daily vitamin D supplement of either +/- 200 IU (low dose) or +/- 500 IU (high dose). At intensive care admission, serum concentrations of 25(OH)D, 1,25 dihydroxyvitamin D(3), vitamin D-binding protein, ionized calcium, IL-1, and soluble IL-6-receptor were low, and PTH was normal. Circulating type-I collagen propeptides were high, alkaline phosphatase was normal, and osteocalcin was low. Bone resorption markers [(carboxy terminal cross-linked telopeptide of type I collagen (betaCTX), pyridinoline, deoxypyridinoline (DPD)] were 6-fold increased. Serum C-reactive protein (CRP) was 40-fold, IL-6 400-fold, TNFalpha levels 5-fold, and osteoprotegerin concentrations 3-fold higher than in controls. Soluble receptor activator of nuclear factor kappaB ligand was undetectable. High-dose vitamin D only slightly increased circulating 25 hydroxy vitamin D (P < 0.05), but 1,25 dihydroxyvitamin D(3) was unaltered. High-dose vitamin D slightly increased serum osteocalcin (P < 0.05) and decreased carboxy terminal propeptide type-I collagen (P < 0.05) but did not affect other bone turnover markers. Bone-specific alkaline phosphatase, urinary pyridinoline and DPD, and serum betaCTX markedly increased with time (P < 0.01). Circulating CRP and IL-6 decreased with time, whereas TNFalpha and IL-1 remained unaltered. The fall in CRP and IL-6 was more pronounced with the high- than low-dose vitamin D (P < 0.05). Except for a mirroring of betaCTX rise by a fall in osteoprotegerin, cytokines were unrelated to the progressively aggravating bone resorption. In conclusion, prolonged critically ill patients were vitamin D deficient. The currently recommended vitamin D dose did not normalize vitamin D status. Furthermore, severe bone hyperresorption further aggravated (up to 15-fold the normal values) with time in intensive care and was associated with impaired osteoblast function.

Reduced activation and increased inactivation of thyroid hormone in tissues of critically ill patients.

Critical illness is often associated with reduced TSH and thyroid hormone secretion as well as marked changes in peripheral thyroid hormone metabolism, resulting in low serum T(3) and high rT(3) levels. To study the mechanism(s) of the latter changes, we determined serum thyroid hormone levels and the expression of the type 1, 2, and 3 iodothyronine deiodinases (D1, D2, and D3) in liver and skeletal muscle from deceased intensive care patients. To study mechanisms underlying these changes, 65 blood samples, 65 liver, and 66 skeletal muscle biopsies were obtained within minutes after death from 80 intensive care unit patients randomized for intensive or conventional insulin treatment. Serum thyroid parameters and the expression of tissue D1-D3 were determined. Serum TSH, T(4), T(3), and the T(3)/rT(3) ratio were lower, whereas serum rT(3) was higher than in normal subjects (P < 0.0001). Liver D1 activity was down-regulated and D3 activity was induced in liver and skeletal muscle. Serum T(3)/rT(3) ratio correlated positively with liver D1 activity (P < 0.001) and negatively with liver D3 activity (ns). These parameters were independent of the type of insulin treatment. Liver D1 and serum T(3)/rT(3) were highest in patients who died from severe brain damage, intermediate in those who died from sepsis or excessive inflammation, and lowest in patients who died from cardiovascular collapse (P < 0.01). Liver D3 showed an opposite relationship. Acute renal failure requiring dialysis and need of inotropes were associated with low liver D1 activity (P < 0.01 and P = 0.06) and high liver D3 (P < 0.01) and skeletal muscle D3 (P < 0.05) activity. Liver D1 activity was negatively correlated with plasma urea (P = 0.002), creatinine (P = 0.06), and bilirubin (P < 0.0001). D1 and D3 mRNA levels corresponded with enzyme activities (both P < 0.001), suggesting regulation of the expression of both deiodinases at the pretranslational level. This is the first study relating tissue deiodinase activities with serum thyroid hormone levels and clinical parameters in a large group of critically ill patients. Liver D1 is down-regulated and D3 (which is not present in liver and skeletal muscle of healthy individuals) is induced, particularly in disease states associated with poor tissue perfusion. These observed changes, in correlation with a low T(3)/rT(3) ratio, may represent tissue-specific ways to reduce thyroid hormone bioactivity during cellular hypoxia and contribute to the low T(3) syndrome of severe illness.