Low circulatory levels of total cholesterol, HDL-C and LDL-C are associated with death of patients with sepsis and critical illness: systematic review, meta-analysis, and perspective of observational studies.

BACKGROUND: Mechanistic studies have established a biological role of sterol metabolism in infection and immunity with clinical data linking deranged cholesterol metabolism during sepsis with poorer outcomes. In this systematic review we assess the relationship between biomarkers of cholesterol homeostasis and mortality in critical illness. METHODS: We identified articles by searching a total of seven electronic databases from inception to October 2023. Prospective observational cohort studies included those subjects who had systemic cholesterol (Total Cholesterol (TC), HDL-C or LDL-C) levels assessed on the first day of ICU admission and short-term mortality recorded. Meta-analysis and meta-regression were used to evaluate overall mean differences in serum cholesterol levels between survivors and non-survivors. Study quality was assessed using the Newcastle-Ottawa Scale. FINDINGS: From 6469 studies identified by searches, 24 studies with 2542 participants were included in meta-analysis. Non-survivors had distinctly lower HDL-C at ICU admission -7.06 mg/dL (95% CI -9.21 to -4.91, p < 0.0001) in comparison with survivors. Corresponding differences were also seen less robustly for TC -21.86 mg/dL (95% CI -31.23 to -12.49, p < 0.0001) and LDL-C -8.79 mg/dL (95% CI, -13.74 to -3.83, p = 0.0005). INTERPRETATION: Systemic cholesterol levels (TC, HDL-C and LDL-C) on admission to critical care are inversely related to mortality. This finding is consistent with the notion that inflammatory and metabolic setpoints are coupled, such that the maladaptive-setpoint changes of cholesterol in critical illness are related to underlying inflammatory processes. We highlight the potential of HDL-biomarkers as early predictors of severity of illness and emphasise that future research should consider the metabolic and functional heterogeneity of HDLs. FUNDING: EU-ERDF-Welsh Government Ser Cymru programme, BBSRC, and EU-FP7 ClouDx-i project (PG).

Recovery from Covid-19 critical illness: A secondary analysis of the ISARIC4C CCP-UK cohort study and the RECOVER trial.

Background: We aimed to compare the prevalence and severity of fatigue in survivors of Covid-19 versus non-Covid-19 critical illness, and to explore potential associations between baseline characteristics and worse recovery. Methods: We conducted a secondary analysis of two prospectively collected datasets. The population included was 92 patients who received invasive mechanical ventilation (IMV) with Covid-19, and 240 patients who received IMV with non-Covid-19 illness before the pandemic. Follow-up data were collected post-hospital discharge using self-reported questionnaires. The main outcome measures were self-reported fatigue severity and the prevalence of severe fatigue (severity >7/10) 3 and 12-months post-hospital discharge. Results: Covid-19 IMV-patients were significantly younger with less prior comorbidity, and more males, than pre-pandemic IMV-patients. At 3-months, the prevalence (38.9% [7/18] vs. 27.1% [51/188]) and severity (median 5.5/10 vs 5.0/10) of fatigue were similar between the Covid-19 and pre-pandemic populations, respectively. At 6-months, the prevalence (10.3% [3/29] vs. 32.5% [54/166]) and severity (median 2.0/10 vs. 5.7/10) of fatigue were less in the Covid-19 cohort. In the total sample of IMV-patients included (i.e. all Covid-19 and pre-pandemic patients), having Covid-19 was significantly associated with less severe fatigue (severity <7/10) after adjusting for age, sex and prior comorbidity (adjusted OR 0.35 (95%CI 0.15-0.76, p=0.01). Conclusion: Fatigue may be less severe after Covid-19 than after other critical illness.

Responsiveness of Critically Ill Adults With Multimorbidity to Rehabilitation Interventions: A Patient-Level Meta-Analysis Using Individual Pooled Data From Four Randomized Trials.

OBJECTIVE: To explore if patient characteristics (pre-existing comorbidity, age, sex, and illness severity) modify the effect of physical rehabilitation (intervention vs control) for the coprimary outcomes health-related quality of life (HRQoL) and objective physical performance using pooled individual patient data from randomized controlled trials (RCTs). DATA SOURCES: Data of individual patients from four critical care physical rehabilitation RCTs. STUDY SELECTION: Eligible trials were identified from a published systematic review. DATA EXTRACTION: Data sharing agreements were executed permitting transfer of anonymized data of individual patients from four trials to form one large, combined dataset. The pooled trial data were analyzed with linear mixed models fitted with fixed effects for treatment group, time, and trial. DATA SYNTHESIS: Four trials contributed data resulting in a combined total of 810 patients (intervention n = 403, control n = 407). After receiving trial rehabilitation interventions, patients with two or more comorbidities had HRQoL scores that were significantly higher and exceeded the minimal important difference at 3 and 6 months compared with the similarly comorbid control group (based on the Physical Component Summary score (Wald test p = 0.041). Patients with one or no comorbidities who received intervention had no HRQoL outcome differences at 3 and 6 months when compared with similarly comorbid control patients. No patient characteristic modified the physical performance outcome in patients who received physical rehabilitation. CONCLUSIONS: The identification of a target group with two or more comorbidities who derived benefits from the trial interventions is an important finding and provides direction for future investigations into the effect of rehabilitation. The multimorbid post-ICU population may be a select population for future prospective investigations into the effect of physical rehabilitation.

Hypoxia shapes the immune landscape in lung injury and promotes the persistence of inflammation.

Hypoxemia is a defining feature of acute respiratory distress syndrome (ARDS), an often-fatal complication of pulmonary or systemic inflammation, yet the resulting tissue hypoxia, and its impact on immune responses, is often neglected. In the present study, we have shown that ARDS patients were hypoxemic and monocytopenic within the first 48 h of ventilation. Monocytopenia was also observed in mouse models of hypoxic acute lung injury, in which hypoxemia drove the suppression of type I interferon signaling in the bone marrow. This impaired monopoiesis resulted in reduced accumulation of monocyte-derived macrophages and enhanced neutrophil-mediated inflammation in the lung. Administration of colony-stimulating factor 1 in mice with hypoxic lung injury rescued the monocytopenia, altered the phenotype of circulating monocytes, increased monocyte-derived macrophages in the lung and limited injury. Thus, tissue hypoxia altered the dynamics of the immune response to the detriment of the host and interventions to address the aberrant response offer new therapeutic strategies for ARDS.

Intravenous iron to treat anaemia following critical care: a multicentre feasibility randomised trial.

BACKGROUND: Anaemia is common and associated with poor outcomes in survivors of critical illness. However, the optimal treatment strategy is unclear. METHODS: We conducted a multicentre, feasibility RCT to compare either a single dose of ferric carboxymaltose 1000 mg i.v. or usual care in patients being discharged from the ICU with moderate or severe anaemia (haemoglobin ≤100 g L-1). We collected data on feasibility (recruitment, randomisation, follow-up), biological efficacy, and clinical outcomes. RESULTS: Ninety-eight participants were randomly allocated (49 in each arm). The overall recruitment rate was 34% with 6.5 participants recruited on average per month. Forty-seven of 49 (96%) participants received the intervention. Patient-reported outcome measures were available for 79/93 (85%) survivors at 90 days. Intravenous iron resulted in a higher mean (standard deviation [sd]) haemoglobin at 28 days (119.8 [13.3] vs 106.7 [14.9] g L-1) and 90 days (130.5 [15.1] vs 122.7 [17.3] g L-1), adjusted mean difference (10.98 g L-1; 95% confidence interval [CI], 4.96-17.01; P<0.001) over 90 days after randomisation. Infection rates were similar in both groups. Hospital readmissions at 90 days post-ICU discharge were lower in the i.v. iron group (7/40 vs 15/39; risk ratio=0.46; 95% CI, 0.21-0.99; P=0.037). The median (inter-quartile range) post-ICU hospital stay was shorter in the i.v. iron group but did not reach statistical significance (5.0 [3.0-13.0] vs 9.0 [5.0-16.0] days, P=0.15). CONCLUSION: A large, multicentre RCT of i.v. iron to treat anaemia in survivors of critical illness appears feasible and is necessary to determine the effects on patient-centred outcomes. CLINICAL TRIAL REGISTRATION: ISRCTN13721808 (www.isrctn.com).

Vitamin D insufficiency in COVID-19 and influenza A, and critical illness survivors: a cross-sectional study.

OBJECTIVES: The steroid hormone vitamin D has roles in immunomodulation and bone health. Insufficiency is associated with susceptibility to respiratory infections. We report 25-hydroxy vitamin D (25(OH)D) measurements in hospitalised people with COVID-19 and influenza A and in survivors of critical illness to test the hypotheses that vitamin D insufficiency scales with illness severity and persists in survivors. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: Plasma was obtained from 295 hospitalised people with COVID-19 (International Severe Acute Respiratory and emerging Infections Consortium (ISARIC)/WHO Clinical Characterization Protocol for Severe Emerging Infections UK study), 93 with influenza A (Mechanisms of Severe Acute Influenza Consortium (MOSAIC) study, during the 2009-2010 H1N1 pandemic) and 139 survivors of non-selected critical illness (prior to the COVID-19 pandemic). Total 25(OH)D was measured by liquid chromatography-tandem mass spectrometry. Free 25(OH)D was measured by ELISA in COVID-19 samples. OUTCOME MEASURES: Receipt of invasive mechanical ventilation (IMV) and in-hospital mortality. RESULTS: Vitamin D insufficiency (total 25(OH)D 25-50 nmol/L) and deficiency (<25 nmol/L) were prevalent in COVID-19 (29.3% and 44.4%, respectively), influenza A (47.3% and 37.6%) and critical illness survivors (30.2% and 56.8%). In COVID-19 and influenza A, total 25(OH)D measured early in illness was lower in patients who received IMV (19.6 vs 31.9 nmol/L (p<0.0001) and 22.9 vs 31.1 nmol/L (p=0.0009), respectively). In COVID-19, biologically active free 25(OH)D correlated with total 25(OH)D and was lower in patients who received IMV, but was not associated with selected circulating inflammatory mediators. CONCLUSIONS: Vitamin D deficiency/insufficiency was present in majority of hospitalised patients with COVID-19 or influenza A and correlated with severity and persisted in critical illness survivors at concentrations expected to disrupt bone metabolism. These findings support early supplementation trials to determine if insufficiency is causal in progression to severe disease, and investigation of longer-term bone health outcomes.

The 6 Ps of post-ICU recovery: application of a shared conceptual model.

PURPOSE OF REVIEW: We aimed to explore, through a conceptual model, how we can maximize the post-ICU recovery of patients with ICU-acquired weakness (ICU-AW). The '6 Ps' were used to structure our research questions, what are the Predisposing (pre-ICU patient characteristics), Precipitating (ICU exposures) and Perpetuating (hinder recovery) risk factors for ICU-AW (Problem) and what Protective strategies and Proactive treatment can we adopt to improve muscle mass, strength and function of these patients? RECENT FINDINGS: Examination of the relationship between pre-ICU patient characteristics with ICU-AW and post-ICU factors that prolong recovery are limited. Our understanding of the pathophysiology of the condition is improving, however, much of the biological mechanisms of ICU-AW and persistent weakness remain unknown. Investigation into the ICU-AW phenotype and prediction tools would be of great clinical utility. Further research on ICU-AW muscle biology and recovery may permit the application of precision and personalized medicine to therapeutic interventions. SUMMARY: A structured approach to clinical practice and future research to better understand the mechanism (Problem), and identify Predisposing, Precipitating and Perpetuating risk factors will advance the field in better managing ICU-AW through implementation of Protective strategies and Proactive multimodal treatments.

Response to physical rehabilitation and recovery trajectories following critical illness: individual participant data meta-analysis protocol.

INTRODUCTION: The number of inconclusive physical rehabilitation randomised controlled trials for patients with critical illness is increasing. Evidence suggests critical illness patient subgroups may exist that benefit from targeted physical rehabilitation interventions that could improve their recovery trajectory. We aim to identify critical illness patient subgroups that respond to physical rehabilitation and map recovery trajectories according to physical function and quality of life outcomes. Additionally, the utilisation of healthcare resources will be examined for subgroups identified. METHODS AND ANALYSIS: This is an individual participant data meta-analysis protocol. A systematic literature review was conducted for randomised controlled trials that delivered additional physical rehabilitation for patients with critical illness during their acute hospital stay, assessed chronic disease burden, with a minimum follow-up period of 3 months measuring performance-based physical function and health-related quality of life outcomes. From 2178 records retrieved in the systematic literature review, four eligible trials were identified by two independent reviewers. Principal investigators of eligible trials were invited to contribute their data to this individual participant data meta-analysis. Risk of bias will be assessed (Cochrane risk of bias tool for randomised trials). Participant and trial characteristics, interventions and outcomes data of included studies will be summarised. Meta-analyses will entail a one-stage model, which will account for the heterogeneity across and the clustering between studies. Multiple imputation using chained equations will be used to account for the missing data. ETHICS AND DISSEMINATION: This individual participant data meta-analysis does not require ethical review as anonymised participant data will be used and no new data collected. Additionally, eligible trials were granted approval by institutional review boards or research ethics committees and informed consent was provided for participants. Data sharing agreements are in place permitting contribution of data. The study findings will be disseminated at conferences and through peer-reviewed publications. PROSPERO REGISTRATION NUMBER: CRD42019152526.

Socioeconomic Position and Health Outcomes Following Critical Illness: A Systematic Review.

OBJECTIVES: Systematically review evidence examining association between preadmission socioeconomic position and physical function, health-related quality of life and survival following critical illness. DATA SOURCES: Four electronic databases (MEDLINE, Embase, CINAHL, CENTRAL) and personal libraries were searched. Reference lists of eligible articles were cross-checked. STUDY SELECTION: Primary quantitative studies reporting association between socioeconomic position and physical function, health-related quality of life, or survival of adults admitted to the ICU were included. DATA EXTRACTION: Performed by two reviewers independently in duplicate using a prepiloted data extraction form. Quality appraisal was completed by two reviewers independently in duplicate using standardized algorithms and checklists. The Preferred Reporting Items for Systematic Reviews guidelines were followed. DATA SYNTHESIS: From 1,799 records, 10 studies were included, one examining association of socioeconomic position with health-related quality of life and five with survival. Four studies accounted for socioeconomic position in survival analyses. Patients with lower socioeconomic position were found to have higher ICU, in-hospital, 30-day, and long-term mortality and lower 6-month Short Form-12 Mental Component Summary scores. No articles examined socioeconomic position and performance-based physical function. Notable variability in methods of socioeconomic position assessment was observed. CONCLUSIONS: Lower socioeconomic position is associated with higher mortality and lower 6-month Short Form-12 Mental Component Summary scores following critical illness. Effect on performance-based physical function is unknown. We make recommendations for consistent socioeconomic position measurement in future ICU studies.

Comparison of Unyvero P55 Pneumonia Cartridge, in-house PCR and culture for the identification of respiratory pathogens and antibiotic resistance in bronchoalveolar lavage fluids in the critical care setting.

Faster respiratory pathogen detection and antibiotic resistance identification are important in critical care due to the severity of illness, significant prior antibiotic exposure and infection control implications. Our objective was to compare the performance of the commercial Unyvero P55 Pneumonia Cartridge (Curetis AG) with routine bacterial culture methods and in-house bacterial multiplex real-time PCR assays. Seventy-four bronchoalveolar lavage specimens from patients admitted to a Scottish intensive care unit (ICU) over a 33-month period were tested prospectively by routine culture and viral PCR and retrospectively by Unyvero P55 and in-house bacterial PCR. Sensitivity/specificity was 56.9%/58.5% and 63.2%/54.8% for the Unyvero P55 and in-house bacterial PCR panels respectively; sensitivity for in-panel targets was 63.5 and 83.7% respectively. Additional organisms were detected by Unyvero P55 and in-house bacterial PCR panels in 16.2% specimens. Antibiotics were changed on the basis of routine test results in 48.3% cases; of these, true-positive or true-negative results would have been obtained earlier by Unyvero P55 or in-house bacterial PCR panel in 15 (53.6%) and 17 (60.7%) cases respectively. However, a false-negative molecular test result may have been acted upon in six (21.4%) cases with either assay. Sensitivity/specificity of Unyvero P55 antibiotic resistance detection was 18.8%/94.9% respectively. Molecular testing identified a number of respiratory pathogens in this patient cohort that were not grown in culture, but resistance detection was not a reliable tool for faster antibiotic modification. In their current set-up, molecular tests may only have benefit as additional tests in the ICU pneumonia setting.

Appetite during the recovery phase of critical illness: a cohort study.

BACKGROUND/OBJECTIVES: Reduced appetite is a recognised physiological symptom in survivors of critical illness. While reduced appetite has been reported by patients after intensive care unit (ICU) discharge, quantification using visual analogue scales (VAS) has not been previously performed, and follow-up duration has been limited. We aimed to describe appetite scores in ICU survivors during the first 3 months after ICU discharge and explore association with systemic inflammation. SUBJECTS/METHODS: Secondary analysis of data collected in a complex rehabilitation intervention trial (RECOVER). A subgroup of 193 patients provided specific consent for inclusion in the blood sampling sub-study during consent for the main study. We studied appetite using a VAS; serum C-reactive protein (CRP); interleukin-1ß and interleukin-6 (IL-1ß and IL-6); and hand-grip strength. RESULTS: Median (interquartile range) score on 0-10 appetite VAS was 4.3 (2.0-6.5) 1 week after ICU discharge, improving to 7.1 (4.6-8.9) by 3 months (mean difference 1.7 (0.9-2.4), p < 0.01). Number of days spent in an acute hospital following an intensive care stay was associated with poorer appetite scores (p = 0.03). CRP concentration and appetite were significantly associated at 1 week after ICU discharge (p = 0.01), but not at 3 months after ICU discharge (p = 0.67). CONCLUSIONS: ICU survivors experience reduced appetite during the acute recovery phase of critical illness that could impact on nutritional recovery and this was associated with CRP concentration 1 week after ICU discharge.

Determinants of Health-Related Quality of Life After ICU: Importance of Patient Demographics, Previous Comorbidity, and Severity of Illness.

OBJECTIVES: ICU survivors frequently report reduced health-related quality of life, but the relative importance of preillness versus acute illness factors in survivor populations is not well understood. We aimed to explore health-related quality of life trajectories over 12 months following ICU discharge, patterns of improvement, or deterioration over this period, and the relative importance of demographics (age, gender, social deprivation), preexisting health (Functional Comorbidity Index), and acute illness severity (Acute Physiology and Chronic Health Evaluation II score, ventilation days) as determinants of health-related quality of life and relevant patient-reported symptoms during the year following ICU discharge. DESIGN: Nested cohort study within a previously published randomized controlled trial. SETTING: Two ICUs in Edinburgh, Scotland. PATIENTS: Adult ICU survivors (n = 240) who required more than 48 hours of mechanical ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We prospectively collected data for age, gender, social deprivation (Scottish index of multiple deprivation), preexisting comorbidity (Functional Comorbidity Index), Acute Physiology and Chronic Health Evaluation II score, and days of mechanical ventilation. Health-related quality of life (Medical Outcomes Study Short Form version 2 Physical Component Score and Mental Component Score) and patient-reported symptoms (appetite, fatigue, pain, joint stiffness, and breathlessness) were measured at 3, 6, and 12 months. Mean Physical Component Score and Mental Component Score were reduced at all time points with minimal change between 3 and 12 months. In multivariable analysis, increasing pre-ICU comorbidity count was strongly associated with lower health-related quality of life (Physical Component Score ß = -1.56 [-2.44 to -0.68]; p = 0.001; Mental Component Score ß = -1.45 [-2.37 to -0.53]; p = 0.002) and more severe self-reported symptoms. In contrast, Acute Physiology and Chronic Health Evaluation II score and mechanical ventilation days were not associated with health-related quality of life. Older age (ß = 0.33 [0.19-0.47]; p < 0.001) and lower social deprivation (ß = 1.38 [0.03-2.74]; p = 0.045) were associated with better Mental Component Score health-related quality of life. CONCLUSIONS: Preexisting comorbidity counts, but not severity of ICU illness, are strongly associated with health-related quality of life and physical symptoms in the year following critical illness.

Systemic inflammation after critical illness: relationship with physical recovery and exploration of potential mechanisms.

BACKGROUND: Physical recovery following critical illness is slow, often incomplete and is resistant to rehabilitation interventions. We aimed to explore the contribution of persisting inflammation to recovery, and investigated the potential role of human cytomegalovirus (HCMV) infection in its pathogenesis. METHODS: In an a priori nested inflammatory biomarker study in a post-intensive care unit (ICU) rehabilitation trial (RECOVER; ISRCTN09412438), surviving adult ICU patients ventilated >48 h were enrolled at ICU discharge and blood sampled at ICU discharge (n=184) and 3 month follow-up (N=123). C-reactive protein (CRP), human neutrophil elastase (HNE), interleukin (IL)-1ß, IL-6, IL-8, transforming growth factor ß1 (TGFß1) and secretory leucocyte protease inhibitor (SLPI) were measured. HCMV IgG status was determined (previous exposure), and DNA PCR measured among seropositive patients (lytic infection). Physical outcome measures including the Rivermead Mobility Index (RMI) were measured at 3 months. RESULTS: Many patients had persisting inflammation at 3 months (CRP >3 mg/L in 59%; >10 mg/L in 28%), with proinflammatory phenotype (elevated HNE, IL-6, IL-8, SLPI; low TGFß1). Poorer mobility (RMI) was associated with higher CRP (ß=0.13; p<0.01) and HNE (ß=0.32; p=0.03), even after adjustment for severity of acute illness and pre-existing co-morbidity (CRP ß=0.14; p<0.01; HNE ß=0.30; p=0.04). Patients seropositive for HCMV at ICU discharge (63%) had a more proinflammatory phenotype at 3 months than seronegative patients, despite undetectable HMCV by PCR testing. CONCLUSIONS: Inflammation is prevalent after critical illness and is associated with poor physical recovery during the first 3 months post-ICU discharge. Previous HCMV exposure is associated with a proinflammatory phenotype despite the absence of detectable systemic viraemia. TRIAL REGISTRATION NUMBER: ISRCTN09412438, post results.

Pharmacological Therapy for the Prevention and Treatment of Weakness After Critical Illness: A Systematic Review.

OBJECTIVES: ICU-acquired weakness is a common complication of critical illness and can have significant effects upon functional status and quality of life. As part of preliminary work to inform the design of a randomized trial of a complex intervention to improve recovery from critical illness, we sought to identify pharmacological interventions that may play a role in this area. DATA SOURCES: We systematically reviewed the published literature relating to pharmacological intervention for the treatment and prevention of ICU-acquired weakness. STUDY SELECTION: We searched MEDLINE, EMBASE, CINAHL+, Web of Science, and both U.S. and European trial registries up to July 2014 alongside reviews and reference lists from populations with no age or language restrictions. We included studies that reported a measure of muscle structure or physical function as an outcome measure. DATA EXTRACTION: We estimated pooled odds ratios and 95% CI using data extracted from published articles or where available, original data provided by the authors. Assessment of bias was performed using the Cochrane Collaboration's risk of bias tool. DATA SYNTHESIS: Ten studies met the inclusion criteria. The current body of evidence does not support the use of any pharmacological agent in this setting, although maintaining euglycemia may reduce the prevalence of critical illness polyneuropathy. CONCLUSIONS: At present, no pharmacological intervention can be recommended to prevent or treat ICU-acquired weakness. Further research is required into this field to include more novel agents such as myostatin inhibitors. Challenges in the conduct of research in this area are highlighted.