Persistent inflammation and recovery after intensive care: A systematic review

Persistent Fatigue, Weakness, and Aberrant Muscle Mitochondria in Survivors of Critical COVID-19

OBJECTIVES

Persistent skeletal muscle dysfunction in survivors of critical illness due to acute respiratory failure is common, but biological data elucidating underlying mechanisms are limited. The objective of this study was to elucidate the prevalence of skeletal muscle weakness and fatigue in survivors of critical illness due to COVID-19 and determine if cellular changes associate with persistent skeletal muscle dysfunction.

DESIGN

A prospective observational study in two phases: 1) survivors of critical COVID-19 participating in physical outcome measures while attending an ICU Recovery Clinic at short-term follow-up and 2) a nested cohort of patients performed comprehensive muscle and physical function assessments with a muscle biopsy; data were compared with non-COVID controls.

SETTING

ICU Recovery Clinic and clinical laboratory.

PATIENTS/SUBJECTS

Survivors of critical COVID-19 and non-COVID controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred twenty patients with a median of 56 years old (interquartile range [IQR], 42-65 yr old), 43% female, and 33% individuals of underrepresented race attended follow-up 44 ± 17 days after discharge. Patients had a median Acute Physiology and Chronic Health Evaluation-II score of 24.0 (IQR, 16-29) and 98 patients (82%) required mechanical ventilation with a median duration of 14 days (IQR, 9-21 d). At short-term follow-up significant physical dysfunction was observed with 93% of patients reporting generalized fatigue and performing mean 218 ± 151 meters on 6-minute walk test (45% ± 30% of predicted). Eleven patients from this group agreed to participate in long-term assessment and muscle biopsy occurring a mean 267 ± 98 days after discharge. Muscle tissue from COVID exhibited a greater abundance of M2-like macrophages and satellite cells and lower activity of mitochondrial complex II and complex IV compared with controls.

CONCLUSIONS

Our findings suggest that aberrant repair and altered mitochondrial activity in skeletal muscle associates with long-term impairments in patients surviving an ICU admission for COVID-19.

Association between inflammation and post-intensive care syndrome: a systematic review

Post-intensive care syndrome describes the physical, cognitive and emotional symptoms which persist following critical illness. At present there is limited understanding of the pathological mechanisms contributing to the development of post-intensive care syndrome. The aim of this systematic review was to synthesise current evidence exploring the association between inflammation and features of post-intensive care syndrome in survivors of critical illness. Relevant databases were systematically searched for studies of human participants exposed to critical illness. We sought studies that reported results for biomarkers with an identified role in the pathophysiology of inflammation obtained at any time-point in the patient journey and an outcome measure of any feature of post-intensive care syndrome at any point following hospital discharge. We included 32 studies, with 23 in the primary analysis and nine in a brain injury subgroup analysis. In the primary analysis, 47 different biomarkers were sampled and 44 different outcome measures were employed. Of the biomarkers which were sampled in five or more studies, interleukin-8, C-reactive protein and interleukin-10 most frequently showed associations with post-intensive care syndrome outcomes in 71%, 62% and 60% of studies, respectively. There was variability in terms of which biomarkers were sampled, time-points of sampling and outcome measures reported. Overall, there was mixed evidence of a potential association between an inflammatory process and long-term patient outcomes following critical illness. Further high-quality research is required to develop a longitudinal inflammatory profile of survivors of critical illness over the recovery period and evaluate the association with outcomes.

Central Line Access Is Predictive of Diagnostic Blood Loss and Transfusion in the Surgical Intensive Care Unit

BACKGROUND

Most patients in the surgical intensive care unit (SICU) have anemia and undergo extensive diagnostic laboratory testing (DLT). Consequently, patients undergo RBC transfusion, and many are discharged with anemia, both of which are associated with poorer outcomes.

OBJECTIVE

To characterize DLT blood loss in the SICU.

MATERIALS AND METHODS

We performed a 1-year retrospective study of 291 patients admitted to a SICU. The number of draws, average volume, and estimated discard volume were recorded, along with clinical and laboratory findings.

RESULTS

Patients who underwent greater amounts of DLT had lower hemoglobin levels at discharge (P ≤ .001). Admissions requiring central venous catheter (CVC) access (49.8%) demonstrated significantly higher DLT draws and rates of transfusion.

CONCLUSION

Findings from this study suggest that DLT blood loss contributes to anemia in the SICU, and that the presence and duration of CVC leads to increased testing, anemia, and RBC transfusion.

Characteristics of Mid-Term Post-Intensive Care Syndrome in Patients Attending a Follow-Up Clinic: A Prospective Comparison Between COVID-19 and Non-COVID-19 Survivors

At present, it is not clear if critically ill COVID-19 survivors have different needs in terms of follow-up compared with other critically ill survivors, and thus if duplicated post-ICU trajectories are mandatory.

OBJECTIVES

To compare the post-intensive care syndrome (PICS) of COVID-19 acute respiratory distress syndrome and non-COVID-19 (NC) survivors referred to a follow-up clinic at 3 months (M3) after ICU discharge.

DESIGN SETTING AND PARTICIPANTS

Adults who survived an ICU stay greater than or equal to 7 days and attended the M3 consultation were included in this observational study performed in a post-ICU follow-up clinic of a single tertiary hospital.

MAIN OUTCOMES AND MEASURES

Patients underwent a standardized assessment, addressing health-related quality of life (3-level version of EQ-5D), sleep disorders (Pittsburgh Sleep Quality Index [PSQI]), physical status (Barthel index, handgrip and quadriceps strengths), mental health disorders (Hospital Anxiety and Depression Scale and Impact of Event Scale-Revised [IES-R]), and cognitive impairment (Montreal Cognitive Assessment [MoCA]).

RESULTS

A total of 143 survivors (86 COVID and 57 NC) attended the M3 consultation. Their median age and severity scores were similar. NC patients had a shorter ICU stay (10 d [8-17.2 d]) compared with COVID group (18 d [10.8-30 d]) (p = 0.001). M3 outcomes were similar in the two groups, except for a higher PSQI (p = 0.038) in the COVID group (6 [3-9.5]) versus NC group (4 [2-7]), and a slightly lower Barthel index in the NC group (100 [100-100]) than in the COVID group (100 [85-100]) (p = 0.026). However, the proportion of patients with abnormal values at each score was similar in the two groups. Health-related quality of life was similar in the two groups. The three MoCA (≥ 26), IES-R (<33), and Barthel (=100) were normal in 58 of 143 patients (40.6%). In contrast, 68.5% (98/143) had not returned to their baseline level of daily activities.

CONCLUSIONS AND RELEVANCE

In our follow-up clinic at 3 months after discharge, the proportion of patients presenting alterations in the main PICS domains was similar whether they survived a COVID-19 or another critical illness, despite longer ICU stay in COVID group. Cognition and sleep were the two most affected PICS domains.

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Related Factors of Anemia in Critically Ill Patients: A Prospective Multicenter Study

Anemia is common in critically ill patients; almost 95% of patients admitted to intensive care units (ICUs) have hemoglobin levels below normal. Several causes may explain this phenomenon as well as the tendency to transfuse patients without adequate cause: due to a lack of adherence to protocols, lack of supervision, incomplete transfusion request forms, or a lack of knowledge about the indications, risks, and costs of transfusions. Daily sampling to monitor the coagulation parameters and the acid-base balance can aggravate anemia as the main iatrogenic factor in its production. We studied the association and importance of iatrogenic blood loss and other factors in the incidence of anemia in ICUs. We performed a prospective, observational, multicenter study in five Spanish hospitals. A total of 142 patients with a median age of 58 years (IQI: 48-69), 71.83% male and 28.17% female, were admitted to ICUs without a diagnosis of iatrogenic anemia. During their ICU stay, anemia appeared in 66.90% of the sample, 95 patients, (95% CI: 58.51-74.56%). Risk factors associated with the occurrence of iatrogenic anemia were arterial catheter insertion (72.63% vs. 46.81%, p-value = 0.003), venous catheter insertion (87.37% vs. 72.34%, p-value = 0.023), drainages (33.68% vs. 12. 77%, p-value = 0.038), and ICU stay, where the longer the stay, the higher the rate of iatrogenic anemia (p-value < 0.001). We concluded that there was a statistical significance in the production of iatrogenic anemia due to the daily sampling for laboratory monitoring and critical procedures in intensive care units. The implementation of patient blood management programs could address these issues.

Unresolved inflammation during hospitalization is associated with post-discharge institutionalization and mortality in geriatric rehabilitation inpatients: The RESORT cohort

BACKGROUND

Inflammation contributes to adverse health outcomes in community-dwelling populations. Little is known about inflammation in hospitalized older adults and its association with adverse outcomes. This study aimed to evaluate the association of the inflammatory markers C-reactive protein (CRP) and albumin measured during acute and geriatric rehabilitation hospitalization with institutionalization and mortality in geriatric rehabilitation inpatients.

METHODS

Within the REStORing health of acutely unwell adulTs (RESORT) cohort, CRP and albumin were measured as part of usual care during acute and geriatric rehabilitation hospitalization. Inflammatory markers are presented as median, peak (CRP: maximum; albumin: minimum), variation (interquartile range) and direction of change (increased CRP or decreased albumin: positive or negative difference between last measurement and median of preceding measurements). Logistic regression was used to determine the associations between inflammatory markers and institutionalization at three-month and all-cause mortality at three- and twelve-month post-discharge.

RESULTS

Geriatric rehabilitation inpatients (n = 1846) with a median age of 83.3 years (interquartile range 77.6-88.3) and 56.6% of female were included. Increased CRP during geriatric rehabilitation was associated with institutionalization. Higher median, peak and increased levels of CRP during geriatric rehabilitation but not during acute hospitalization were associated with higher mortality. Lower CRP variation during acute hospitalization but higher CRP variation during geriatric rehabilitation was associated with higher mortality. Lower median level of albumin during both hospitalizations were associated with higher mortality.

CONCLUSIONS

Inflammation characterized by lower albumin during acute hospitalization and, higher CRP and lower albumin during geriatric rehabilitation was associated with mortality in geriatric rehabilitation inpatients. Increased CRP during geriatric rehabilitation was associated with institutionalization. Unresolved inflammation in geriatric rehabilitation might indicate ongoing disease activity leading to adverse outcomes.

Plasma HMGB1 levels and physical performance in ICU survivors

PURPOSE

Physical impairment after critical illness is recognized as a part of the post-intensive care syndrome (PICS). About one third of intensive care unit (ICU) survivors suffer from long-term physical disability, yet the underlying pathophysiological mechanisms remain poorly understood. The pro-inflammatory alarmin, high mobility group box 1 (HMGB1), promotes muscle dysfunction in experimental models, and HMGB1 stays elevated in some patients after ICU discharge. Accordingly, we investigated the relationship between HMGB1 plasma levels and physical performance in ICU survivors.

METHODS

Prospective cohort study of 100 ICU survivors from the general ICU at the Karolinska University Hospital, Sweden. Patients returned for follow up at 3 (58 patients) and 6 months (51 patients) after ICU discharge. Blood samples were collected, and a 6-minute walk test (6-MWT), a handgrip-strength test (HST), and a timed-stands test (TST) were performed.

RESULTS

Compared to reference values of the different physical tests, 16% of patients underperformed at all tests at 3 months and 12% at 6 months. All test results, except hand-grip strength left, improved significantly over the follow-up period (P < .05). There was no significant association between plasma HMGB1 levels at 3 and 6 months and scores on the three tests (6-MWT, TST, and HST) (P = .50-0.69).

CONCLUSION

In this follow-up study of ICU survivors, we found no significant association between plasma HMGB1 levels and physical performance. Additional follow-up studies of HMGB1 plasma levels and muscle function in ICU survivors are still warranted.

EDITORIAL COMMENT

HMGB-1, a marker of cell damage and activation, is known to increase in ICU patients. In study participants at 3- to 6-month post-ICU stay, HMGB-1 levels were still elevated, although no association to the primary outcome, physical performance, was found. Mechanisms for failure to recover physical performance post-ICU remain unclear, and investigations into cause of post-intensive care syndrome need to continue.

TRIAL REGISTRATIONS

ClinicalTrials.gov identifier NCT02914756.

Persistent inflammation worsens short-term outcomes in massive stroke patients

Background

Persistent inflammation is an important driver of disease progression and affects prognosis. Some indicators of inflammation predict short-term outcomes. The relationship between prognosis, especially mortality, and persistent inflammation in massive stroke has not been studied, and this has been the subject of our research.

Methods

From April 1, 2017 to February 1, 2020, consecutive patients were prospectively enrolled. Clinical data, laboratory data, imaging data and follow-up infections morbidity were compared between 2 groups according to modified Rankin scale (mRS) scores (mRS < 3 and ≥ 3) at 1 month. The binomial logistic analysis was used to determine independent factors of 1-month prognosis. Short-term functional outcome, mortality and infection rates in massive stroke with and without persistent inflammation were compared.

Results

One hundred thirty-nine patients with massive stroke were included from 800 patients. We found that admission blood glucose levels (p = 0.005), proportions of cerebral hemispheric (p = 0.001), posterior circulatory (p = 0.035), and lacunar (p = 0.022) ischemia were higher in poor outcome patients; neutrophil-to-lymphocyte ratio (odd ratio = 1.87, 95%CI 1.14–3.07, p = 0.013) and blood glucose concentrations (odd ratio = 1.34, 95%CI 1.01–1.79, p = 0.043) can independently predict the short-term prognosis in massive stroke patients. We also found that the incidence of pulmonary infection (p = 0.009), one-month mortality (p = 0.003) and adverse outcomes (p = 0.0005) were higher in patients with persistent inflammation.

Conclusions

This study suggested that persistent inflammation is associated with poor prognosis, 1-month mortality and the occurrence of in-hospital pulmonary infection and that higher baseline inflammation level predicts short-term poor outcomes in massive stroke.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02097-9.

Prevalence of and Recovery From Anemia Following Hospitalization for Critical Illness Among Adults

IMPORTANCE

Anemia is common and has been associated with poor outcomes in the critically ill population, yet the timing and extent of hemoglobin recovery remains incompletely described, which may have important implications for clinical outcomes following discharge from intensive care.

OBJECTIVES

To describe longitudinal changes in anemia status during and after critical illness and assess the associations between hemoglobin concentrations and postdischarge mortality.

DESIGN, SETTING, AND PARTICIPANTS

A population-based cohort study was conducted from January 1, 2010, to December 31, 2016, in Olmsted County, Minnesota; data analysis was performed from June 1 to December 30, 2019. Participants included 6901 adults (age ≥18 years) admitted to intensive care.

MAIN OUTCOMES AND MEASURES

Hemoglobin concentrations in the 12 months before hospitalization, during hospitalization, and in the 12 months after discharge, categorized by anemia severity (mild, hemoglobin ≥10.0 to <12.0 g/dL in women or ≥10.0 to <13.5 g/dL in men; moderate, hemoglobin ≥8.0 to <10.0 g/dL; and severe, hemoglobin <8.0 g/dL). Complete recovery from anemia, defined as attainment of nonanemic status by 12 months post hospitalization, and 12-month mortality were also evaluated.

RESULTS

Of the 6901 patients included in the study, 3792 were men (55%); median (interquartile range [IQR]) age was 67 (IQR, 52-79) years. Prehospitalization hemoglobin concentrations were available in 83% of the population (n = 5694), with median hemoglobin concentrations of 13.1 (IQR, 11.6-14.4) g/dL. Forty-one percent of the patients (n = 2320) had anemia preceding hospitalization. Hemoglobin values at hospital discharge were 10.8 g/dL (IQR, 9.5-12.4 g/dL), with 80% (n = 5182 of 6460) having anemia: 58% mild, 39% moderate, and 3% severe. The prevalence of anemia post hospitalization was 56% (95% CI, 55%-58%) at 3 months, 52% (95% CI, 50%-54%) at 6 months, and 45% (95% CI, 43%-47%) at 12 months among those alive with available hemoglobin measurements. Rates of complete recovery from anemia at 12 months were 58% (95% CI, 56%-61%) for mild anemia, 39% (95% CI, 36%-42%) for moderate anemia, and 24% (95% CI, 15%-34%) for severe anemia. Of those without baseline anemia surviving hospitalization, 74% of the patients were anemic at hospital discharge, with rates of complete 12-month recovery of 73% (95% CI, 69%-76%) for mild anemia, 62% (95% CI, 57%-68%) for moderate anemia, and 59% (95% CI, 35%-82%) for severe anemia. Higher hospital discharge hemoglobin concentrations were associated with decreased mortality after multivariable adjustment (hazard ratio, 0.95 per 1-g/dL increase; 95% CI, 0.90-0.99, P = .02).

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that anemia is common and often persistent in the first year after critical illness. Further studies are warranted to identify distinct anemia recovery profiles and assess associations with clinical outcomes.

Anemia in Critically Ill Patients With Acute Respiratory Distress Syndrome and Posthospitalization Physical Outcomes

Objective:

Anemia is common during critical illness and often persists after hospital discharge; however, its potential association with physical outcomes after critical illness is unclear. Our objective was to assess the associations between hemoglobin at intensive care unit (ICU) and hospital discharge with physical status at 3-month follow-up in acute respiratory distress syndrome (ARDS) survivors.

Methods:

This is a secondary analysis of a multisite prospective cohort study of 195 mechanically ventilated ARDS survivors from 13 ICUs at 4 teaching hospitals in Baltimore, Maryland. Multivariable regression was utilized to assess the relationships between ICU and hospital discharge hemoglobin concentrations with measures of physical status at 3 months, including muscle strength (Medical Research Council sumscore), exercise capacity (6-minute walk distance [6MWD]), and self-reported physical functioning (36-Item Short-Form Health Survey [SF-36v2] Physical Function score and Activities of Daily Living [ADL] dependencies).

Results:

Median (interquartile range) hemoglobin concentrations at ICU and hospital discharge were 9.5 (8.5-10.7) and 10.0 (9.0-11.2) g/dL, respectively. In multivariable regression analyses, higher ICU discharge hemoglobin concentrations (per 1 g/dL) were associated with greater 3-month 6MWD mean percent of predicted (3.7% [95% confidence interval 0.8%-6.5%]; P = .01) and fewer ADL dependencies (−0.2 [−0.4 to −0.1]; P = .02), but not with percentage of maximal muscle strength (0.7% [−0.9 to 2.3]; P = .37) or SF-36v2 normalized Physical Function scores (0.8 [−0.3 to 1.9]; P = .15). The associations of physical outcomes and hospital discharge hemoglobin concentrations were qualitatively similar, but none were statistically significant.

Conclusions:

In ARDS survivors, higher hemoglobin concentrations at ICU discharge, but not hospital discharge, were significantly associated with improved exercise capacity and fewer ADL dependencies. Future studies are warranted to further assess these relationships.

Effect of Permissive Underfeeding with Intensive Insulin Therapy on MCP-1, sICAM-1, and TF in Critically Ill Patients

Purpose: This study examined the effect of permissive underfeeding compared to target feeding and intensive insulin therapy (IIT) compared to conventional insulin therapy (CIT) on the inflammatory mediators monocyte chemoattractant protein 1 (MCP-1), soluble intercellular adhesion molecule 1 (sICAM-1), and tissue factor (TF) in critically ill patients. Methodology: This was a substudy of a 2 × 2 factorial design randomized controlled trial in which intensive care unit (ICU) patients were randomized into permissive underfeeding compared to target feeding groups and into IIT compared to CIT groups (ISRCTN96294863). In this substudy, we included 91 patients with almost equal numbers across randomization groups. Blood samples were collected at baseline and at days 3, 5, and 7 of an ICU stay. Linear mixed models were used to assess the differences in MCP-1, sICAM-1, and TF across randomization groups over time. Results: Baseline characteristics were balanced across randomization groups. Daily caloric intake was significantly higher in the target feeding than in the permissive underfeeding groups (P-value < 0.01), and the daily insulin dose was significantly higher in the IIT than in the CIT groups (P-value < 0.01). MCP-1, sICAM-1, and TF did not show any significant difference between the randomization groups, while there was a time effect for MCP-1. Baseline sequential organ failure assessment (SOFA) score and platelets had a significant effect on sICAM-1 (P-value < 0.01). For TF, there was a significant association with age (P-value < 0.01). Conclusions: Although it has been previously demonstrated that insulin inhibits MCP-1, sICAM-1 in critically ill patients, and TF in non-critically ill patients, our study demonstrated that IIT in critically ill patients did not affect these inflammatory mediators. Similarly, caloric intake had a negligible effect on the inflammatory mediators studied.

Nutrition risk screening in the ICU

PURPOSE OF REVIEW

To review recent studies that may help to identify patients in the ICU who benefit from nutrition support.

RECENT FINDINGS

One recent controlled trial did not show any clinical benefit of nutrition support among a sample of ICU patients who were hitherto believed to benefit from nutrition support. Several recent observational studies suggest benefit of nutrition support among patients who have a high nutric score, in itself derived from an observational study.

SUMMARY

Regrettably, the decision about nutrition support in ICU patients still depends on physiological reasoning: a high degree of inflammation/stress metabolism, which will last for a considerable time, especially among those who are fragile (already malnourished, elderly, those with chronic diseases and/or other comorbidities).

Skeletal Muscle Ultrasound in Critical Care: A Tool in Need of Translation

With the emerging interest in documenting and understanding muscle atrophy and function in critically ill patients and survivors, ultrasonography has transformational potential for measurement of muscle quantity and quality. We discuss the importance of quantifying skeletal muscle in the intensive care unit setting. We also identify the merits and limitations of various modalities that are capable of accurately and precisely measuring muscularity. Ultrasound is emerging as a potentially powerful tool for skeletal muscle quantification; however, there are key challenges that need to be addressed in future work to ensure useful interpretation and comparability of results across diverse observational and interventional studies. Ultrasound presents several methodological challenges, and ultimately muscle quantification combined with metabolic, nutritional, and functional markers will allow optimal patient assessment and prognosis. Moving forward, we recommend that publications include greater detail on landmarking, repeated measures, identification of muscle that was not assessable, and reproducible protocols to more effectively compare results across different studies.

Elevated Omentin Serum Levels Predict Long-Term Survival in Critically Ill Patients

Introduction. Omentin, a recently described adipokine, was shown to be involved in the pathophysiology of inflammatory and infectious diseases. However, its role in critical illness and sepsis is currently unknown. Materials and Methods. Omentin serum concentrations were measured in 117 ICU-patients (84 with septic and 33 with nonseptic disease etiology) admitted to the medical ICU. Results were compared with 50 healthy controls. Results. Omentin serum levels of critically ill patients at admission to the ICU or after 72 hours of ICU treatment were similar compared to healthy controls. Moreover, circulating omentin levels were independent of sepsis and etiology of critical illness. Notably, serum concentrations of omentin could not be linked to concentrations of inflammatory cytokines or routinely used sepsis markers. While serum levels of omentin were not predictive for short term survival during ICU treatment, low omentin concentrations were an independent predictor of patients' overall survival. Omentin levels strongly correlated with that of other adipokines (e.g., leptin receptor or adiponectin), which have also been identified as prognostic markers in critical illness. Conclusions. Although circulating omentin levels did not differ between ICU-patients and controls, elevated omentin levels were predictive for an impaired patients' long term survival.