Muscular Ultrasound, Syndecan-1 and Procalcitonin Serum Levels to Assess Intensive Care Unit-Acquired Weakness

Longitudinal Assessment of Blood-Based Inflammatory, Neuromuscular, and Neurovascular Biomarker Profiles in Intensive Care Unit-Acquired Weakness: A Prospective Single-Center Cohort Study

BACKGROUND

The diagnosis of intensive care unit (ICU)-acquired weakness (ICUAW) and critical illness neuromyopathy (CINM) is frequently hampered in the clinical routine. We evaluated a novel panel of blood-based inflammatory, neuromuscular, and neurovascular biomarkers as an alternative diagnostic approach for ICUAW and CINM.

METHODS

Patients admitted to the ICU with a Sequential Organ Failure Assessment score of ≥ 8 on 3 consecutive days within the first 5 days as well as healthy controls were enrolled. The Medical Research Council Sum Score (MRCSS) was calculated, and motor and sensory electroneurography (ENG) for assessment of peripheral nerve function were performed at days 3 and 10. ICUAW was defined by an MRCSS < 48 and CINM by pathological ENG alterations, both at day 10. Blood samples were taken at days 3, 10, and 17 for quantitative analysis of 18 different biomarkers (white blood cell count, C-reactive protein, procalcitonin, C-terminal agrin filament, fatty-acid-binding protein 3, growth and differentiation factor 15, syndecan 1, troponin I, interferon-γ, tumor necrosis factor-α, interleukin-1α [IL-1α], IL-1β, IL-4, IL-6, IL-8, IL-10, IL-13, and monocyte chemoattractant protein 1). Results of the biomarker analysis were categorized according to the ICUAW and CINM status. Clinical outcome was assessed after 3 months.

RESULTS

Between October 2016 and December 2018, 38 critically ill patients, grouped into ICUAW (18 with and 20 without) and CINM (18 with and 17 without), as well as ten healthy volunteers were included. Biomarkers were significantly elevated in critically ill patients compared to healthy controls and correlated with disease severity and 3-month outcome parameters. However, none of the biomarkers enabled discrimination of patients with and without neuromuscular impairment, irrespective of applied classification.

CONCLUSIONS

Blood-based biomarkers are generally elevated in ICU patients but do not identify patients with ICUAW or CINM.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02706314.

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.

Impact of early high protein intake in critically ill patients: a randomized controlled trial

BACKGROUND

Conflicting findings regarding the impact of High protein intake during the early phase in critically ill patients have been reported. Therefore, we aimed to assess the influence of higher early protein intake on the prognosis of critically ill patients.

METHODS

This randomized controlled trial involved 173 critically ill patients who stayed in the Intensive Care Unit/Emergency ICU (ICU/EICU) for at least 7 days. The Low group (n = 87) and High group (n = 86) received protein supplementation of 0.8 g/kg.d and 1.5 g/kg.d, respectively, within 1-3 days of enteral nutrition (EN) initiation, with both groups transitioning to 1.5 g/kg.d on the 4th day. The serum prealbumin (PA), blood urea nitrogen/creatinine, and rectus femoris muscle thickness and cross-sectional area of all patients was measured on the 1th, 3rd, 5th, 7th day, and the day of ICU/EICU discharge.

RESULTS

Patients in both Low and High groups showed no significant differences in age, APACHE II scores, or other demographic and baseline characteristics. There were also no significant differences in the primary outcome (28-day mortality rate) and secondary outcomes (incidence rate of refeeding syndrome and EN tolerance score) between the two groups. However, the Low group exhibited a significantly higher 28-day mortality rate (HR = 2.462, 95% CI: 1.021-5.936, P = 0.045) compared to High group, as determined by Cox proportional hazards models incorporating the time factor. The High group exhibited significantly shorter durations of mechanical ventilation and ICU stay compared to the Low group. Serum PA levels were higher, and rectus femoris muscle atrophy rates were lower in the High group. Furthermore, for septic patients, high protein intake significantly reduced the 28-day mortality rate despite a small sample size (n = 34).

CONCLUSIONS

Our study indicates that increasing early protein intake to 1.5 g/kg.d may be safe and help improve the nutritional status and prognosis of critically ill patients.

TRIAL REGISTRATION

This study was registered with the Chinese Clinical Trial Registry (ChiCTR2000039997, https://www.chictr.org.cn/ ).

Ultrasound for measurement of skeletal muscle mass quantity and muscle composition/architecture in critically ill patients: A scoping review on studies' aims, methods, and findings

AIMS

This scoping review aimed to identify, explore, and map the objectives, methodological aspects, and results of studies that used ultrasound (US) to assess skeletal muscle (SM) in critically ill patients.

METHODS

A scoping review was conducted according to the Joanna Briggs Institute's methodology. All studies that evaluated SM parameters from the US in patients admitted to the intensive care unit (ICU) were considered eligible. We categorized muscle thickness and cross-sectional area as parameters for assessing SM quantity, while echogenicity, fascicle length, and pennation angle analysis were used to evaluate muscle "quality" (composition/architecture). A literature search was conducted using four databases for articles published until December 2022. Independent reviewers selected the studies and extracted data. Descriptive statistics were calculated to present the results.

RESULTS

A total of 107 studies were included, the majority of which were prospective cohort studies (59.8 %) conducted in general ICUs (49.5 %). The most frequent objective of the studies was to evaluate SM quantity depletion during the ICU stay (25.2 %), followed by determining whether a specific intervention would modify SM (21.5 %). Most studies performed serial SM evaluations (76.1 %). The rectus femoris muscle thickness was evaluated in most studies (67.9 %), followed by the rectus femoris cross-sectional area (54.3 %) and the vastus intermedius muscle thickness (40.2 %). The studies demonstrated the feasibility and reproducibility of US for SM evaluation, especially related to quantitative parameters. Most studies (70.3 %) reported significant SM quantity depletion during hospitalization. However, the accuracy of the US in measuring SM varied across the studies.

CONCLUSIONS

The lack of detailed description and standardization in the protocols adopted by the studies included in this scoping review precludes the translation of the evidence related to US for SM assessment into clinical practice.

[Intensive care unit-acquired weakness-Diagnostic value of neuromuscular ultrasound]

Intensive care unit-acquired weakness (ICUAW) is one of the most common neuromuscular complications in intensive care medicine. The clinical diagnosis and assessment of the severity using established diagnostic methods (e.g., clinical examination using the Medical Research Council Sum Score or electrophysiological examination) can be difficult or even impossible, especially in sedated, ventilated and delirious patients. Neuromuscular ultrasound (NMUS) has increasingly been investigated in ICUAW as an easy to use noninvasive and mostly patient compliance-independent diagnostic alternative. It has been shown that NMUS appears to be a promising tool to detect ICUAW, to assess the severity of muscular weakness and to monitor the clinical progression. Further studies are needed to standardize the methodology, to evaluate the training effort and to optimize outcome predication. The formulation of an interdisciplinary neurological and anesthesiological training curriculum is warranted to establish NMUS as a complementary diagnostic method of ICUAW in daily clinical practice.

Neuromuscular Ultrasound in Intensive Care Unit-Acquired Weakness: Current State and Future Directions

Intensive care unit-acquired weakness (ICUAW) is one of the most common causes of muscle atrophy and functional disability in critically ill intensive care patients. Clinical examination, manual muscle strength testing and monitoring are frequently hampered by sedation, delirium and cognitive impairment. Many different attempts have been made to evaluate alternative compliance-independent methods, such as muscle biopsies, nerve conduction studies, electromyography and serum biomarkers. However, they are invasive, time-consuming and often require special expertise to perform, making them vastly impractical for daily intensive care medicine. Ultrasound is a broadly accepted, non-invasive, bedside-accessible diagnostic tool and well established in various clinical applications. Hereby, neuromuscular ultrasound (NMUS), in particular, has been proven to be of significant diagnostic value in many different neuromuscular diseases. In ICUAW, NMUS has been shown to detect and monitor alterations of muscles and nerves, and might help to predict patient outcome. This narrative review is focused on the recent scientific literature investigating NMUS in ICUAW and highlights the current state and future opportunities of this promising diagnostic tool.

Mitochondrial Dysfunction in Intensive Care Unit-Acquired Weakness and Critical Illness Myopathy: A Narrative Review

Mitochondria are key structures providing most of the energy needed to maintain homeostasis. They are the main source of adenosine triphosphate (ATP), participate in glucose, lipid and amino acid metabolism, store calcium and are integral components in various intracellular signaling cascades. However, due to their crucial role in cellular integrity, mitochondrial damage and dysregulation in the context of critical illness can severely impair organ function, leading to energetic crisis and organ failure. Skeletal muscle tissue is rich in mitochondria and, therefore, particularly vulnerable to mitochondrial dysfunction. Intensive care unit-acquired weakness (ICUAW) and critical illness myopathy (CIM) are phenomena of generalized weakness and atrophying skeletal muscle wasting, including preferential myosin breakdown in critical illness, which has also been linked to mitochondrial failure. Hence, imbalanced mitochondrial dynamics, dysregulation of the respiratory chain complexes, alterations in gene expression, disturbed signal transduction as well as impaired nutrient utilization have been proposed as underlying mechanisms. This narrative review aims to highlight the current known molecular mechanisms immanent in mitochondrial dysfunction of patients suffering from ICUAW and CIM, as well as to discuss possible implications for muscle phenotype, function and therapeutic approaches.

A Global Survey on Diagnostic, Therapeutic and Preventive Strategies in Intensive Care Unit-Acquired Weakness

Background and Objectives: Intensive care unit-acquired weakness (ICU-AW) is one of the most frequent neuromuscular complications in critically ill patients. We conducted a global survey to evaluate the current practices of diagnostics, treatment and prevention in patients with ICU-AW. Materials and Methods: A pre-survey was created with international experts. After revision, the final survey was endorsed by the European Society of Intensive Care Medicine (ESICM) using the online platform SurveyMonkey®. In 27 items, we addressed strategies of diagnostics, therapy and prevention. An invitation link was sent by email to all ESICM members. Furthermore, the survey was available on the ESICM homepage. Results: A total of 154 healthcare professionals from 39 countries participated in the survey. An ICU-AW screening protocol was used by 20% (28/140) of participants. Forty-four percent (62/141) of all participants reported performing routine screening for ICU-AW, using clinical examination as the method of choice (124/141, 87.9%). Almost 63% (84/134) of the participants reported using current treatment strategies for patients with ICU-AW. The use of treatment and prevention strategies differed between intensivists and non-intensivists regarding the reduction in sedatives (80.0% vs. 52.6%, p = 0.002), neuromuscular blocking agents (76.4% vs. 50%, p = 0.004), corticosteroids (69.1% vs. 37.2%, p < 0.001) and glycemic control regimes (50.9% vs. 23.1%, p = 0.002). Mobilization and physical activity are the most frequently reported treatment strategies for ICU-AW (111/134, 82.9%). The availability of physiotherapists (92/134, 68.7%) and the lack of knowledge about ICU-AW within the medical team (83/134, 61.9%) were the main obstacles to the implementation of the strategies. The necessity to develop guidelines for the screening, diagnosing, treatment and prevention of ICU-AW was recognized by 95% (127/133) of participants. Conclusions: A great heterogeneity regarding diagnostics, treatment and prevention of ICU-AW was reported internationally. Comprehensive guidelines with evidence-based recommendations for ICU-AW management are needed.

Evaluation of Changes in Quadriceps Femoris Muscle in Critically III Children Using Ultrasonography

OBJECTIVE

To measure changes in muscle thickness and echogenicity, reflecting muscle bulk and quality, respectively, of quadriceps femoris (QF), in critically ill children.

METHODS

This study was done on 58 children aged 1-18 y requiring mechanical ventilation, admitted in a pediatric intensive care unit (PICU) of a tertiary care hospital from January 2018 to June 2019. QF thickness was measured twice in longitudinal plane and twice in transverse plane, and an average of these four measurements was used. Muscle quality was assessed using ImageJ software to determine the mean echogenicity, and was calculated separately for vastus intermedius and rectus femoris. These observations were repeated on day 3 and day 7 of the ICU stay.

RESULTS

The median muscle thickness of QF was 1.58 cm, and vastus intermedius and rectus femoris echogenicity was 35.5 and 25.88 units, respectively in the present cohort, with median age of 6 y. Only 36 of the 58 patients underwent day 7 ultrasonography, as the remainder were either extubated or died. There was no significant change in the muscle thickness over 7 d. Rectus femoris echogenicity increased significantly over 7 d by 16.1% (p = 0.03). Baseline vastus intermedius echogenicity was significantly higher in patients who subsequently died during the course of their illness (p = 0.026).

CONCLUSION

There was a significant change in rectus femoris echogenicity, but not in QF thickness. Echogenicity rather than muscle thickness may be a more sensitive marker for changes in muscle properties.

Safety and Feasibility Assessment of Repetitive Vascular Occlusion Stimulus (RVOS) Application to Multi-Organ Failure Critically Ill Patients: A Pilot Randomised Controlled Trial

Muscle wasting is implicated in the pathogenesis of intensive care unit acquired weakness (ICU-AW), affecting 40% of patients and causing long-term physical disability. A repetitive vascular occlusion stimulus (RVOS) limits muscle atrophy in healthy and orthopaedic subjects, thus, we explored its application to ICU patients. Adult multi-organ failure patients received standard care +/- twice daily RVOS {4 cycles of 5 min tourniquet inflation to 50 mmHg supra-systolic blood pressure, and 5 min complete deflation} for 10 days. Serious adverse events (SAEs), tolerability, feasibility, acceptability, and exploratory outcomes of the rectus femoris cross-sectional area (RFCSA), echogenicity, clinical outcomes, and blood biomarkers were assessed. Only 12 of the intended 32 participants were recruited. RVOS sessions (76.1%) were delivered to five participants and two could not tolerate it. No SAEs occurred; 75% of participants and 82% of clinical staff strongly agreed or agreed that RVOS is an acceptable treatment. RFCSA fell significantly and echogenicity increased in controls (n = 5) and intervention subjects (n = 4). The intervention group was associated with less frequent acute kidney injury (AKI), a greater decrease in the total sequential organ failure assessment score (SOFA) score, and increased insulin-like growth factor-1 (IGF-1), and reduced syndecan-1, interleukin-4 (IL-4) and Tumor necrosis factor receptor type II (TNF-RII) levels. RVOS application appears safe and acceptable, but protocol modifications are required to improve tolerability and recruitment. There were signals of possible clinical benefit relating to RVOS application.

Sonographic Evaluation of Muscle Echogenicity for the Detection of Intensive Care Unit-Acquired Weakness: A Pilot Single-Center Prospective Cohort Study

Qualitative assessment by the Heckmatt scale (HS) and quantitative greyscale analysis of muscle echogenicity were compared for their value in detecting intensive care unit-acquired weakness (ICU-AW). We performed muscle ultrasound (MUS) of eight skeletal muscles on day 3 and day 10 after ICU admission. We calculated the global mean greyscale score (MGS), the global mean z-score (MZS) and the global mean Heckmatt score (MHS). Longitudinal outcome was defined by the modified Rankin scale (mRS) and Barthel index (BI) after 100 days. In total, 652 ultrasound pictures from 38 critically ill patients (18 with and 20 without ICU-AW) and 10 controls were analyzed. Patients with ICU-AW had a higher MHS on day 10 compared to patients without ICU-AW (2.6 (0.4) vs. 2.2 (0.4), p = 0.006). The MHS was superior to ROC analysis (cut-off: 2.2, AUC: 0.79, p = 0.003, sensitivity 86%, specificity 60%) in detecting ICU-AW compared to MGS and MZS on day 10. The MHS correlated with the Medical Research Council sum score (MRC-SS) (r = −0.45, p = 0.004), the mRS (r = 0.45; p = 0.007) and BI (r = −0.38, p = 0.04) on day 100. Qualitative MUS analysis seems superior to quantitative greyscale analysis of muscle echogenicity for the detection of ICU-AW.

[Intensive Care Unit-Acquired Weakness : A nationwide survey on diagnostics, monitoring and treatment strategies on German intensive care units]

Hintergrund

Die „Intensive Care Unit-Acquired Weakness“ (ICU-AW) ist eine der häufigsten Ursachen für eine neuromuskuläre Dysfunktion in der Intensivmedizin. Gegenwärtig fehlen evidenzbasierte Empfehlungen zur Diagnostik, zum Monitoring und zu therapeutischen Maßnahmen.

Ziel der Arbeit

Die Erfassung des derzeitigen Vorgehens bei Diagnostik, Monitoring und präventiven und therapeutischen Ansätzen bei der ICU-AW auf deutschen Intensivstationen.

Material und Methoden

Onlinebefragung von 448 Mitgliedern des Wissenschaftlichen Arbeitskreises Intensivmedizin (WAKI) und des Wissenschaftlichen Arbeitskreises Neuroanästhesie (WAKNA).

Ergebnisse

Insgesamt wurden 68/448 (15,2 %) Fragebogen ausgewertet. Bei 13,4 % (9/67) der Befragten existiert ein strukturiertes diagnostisches Vorgehen zur Detektion der ICU-AW. Für Screening (60/68; 88,2 %) und Verlaufsbeurteilung (57/65; 87,7 %) wird die klinische Untersuchung präferiert. Etablierte Scores, wie der „Medical Research Council sum score“ (MRC-SS) spielen für Screening und Verlaufskontrolle der ICU-AW eine untergeordnete Rolle (7/68; 10,3 % und 7/65; 10,8 %). Mobilisation (45/68; 66,2 %) und Sedativareduktion (38/68; 55,9 %) stellen die häufigsten präventiven und therapeutischen Ansätze dar. Ein Mangel an Physiotherapeuten (64/68; 94,1 %) und Pflegekräften (57/68; 83,8 %) wird als Hauptdefizit bei der Versorgung von Patienten mit ICU-AW identifiziert. Insgesamt 91,2 % (62/68) der Befragten befürworten die Erstellung evidenzbasierter Empfehlungen zur Diagnostik, zum Monitoring und zu therapeutischen Ansätzen bei ICU-AW.

Diskussion

Ein einheitliches Konzept für Diagnostik, Monitoring, Prävention und Therapie der ICU-AW auf deutschen Intensivstationen fehlt weitgehend. Innovative diagnostische Ansätze könnten in Zukunft helfen, Patienten mit einem hohem Risiko für eine ICU-AW frühzeitig zu detektieren, präventive Maßnahmen einzuleiten sowie wertvolle prognostische Informationen zu gewinnen.

Zusatzmaterial online

Die Online-Version dieses Beitrags (10.1007/s00101-022-01089-9) enthält den der Studie zugrunde liegenden Fragebogen.

Upper Arm Muscular Echogenicity Predicts Intensive Care Unit-acquired Weakness in Critically Ill Patients

Objectives:

Methods:

Results:

Conclusions:

A novel ex vivo model for critical illness neuromyopathy using freshly resected human colon smooth muscle

Patients suffering from critical illness are at risk to develop critical illness neuromyopathy (CINM). The underlying pathophysiology is complex and controversial. A central question is whether soluble serum factors are involved in the pathogenesis of CINM. In this study, smooth muscle preparations obtained from the colon of patients undergoing elective surgery were used to investigate the effects of serum from critically ill patients. At the time of blood draw, CINM was assessed by clinical rating and electrophysiology. Muscle strips were incubated with serum of healthy controls or patients in organ baths and isometric force was measured. Fifteen samples from healthy controls and 98 from patients were studied. Ratios of responses to electric field stimulation (EFS) before and after incubation were 118% for serum from controls and 51% and 62% with serum from critically ill patients obtained at day 3 and 10 of critical illness, respectively (p = 0.003, One-Way-ANOVA). Responses to carbachol and high-K⁺ were equal between these groups. Ratios of post/pre-EFS responses correlated with less severe CINM. These results support the existence of pathogenic, i.e. neurotoxic factors in the serum of critically ill patients. Using human colon smooth muscle as a bioassay may facilitate their future molecular identification.

Changes in muscle ultrasound for the diagnosis of intensive care unit acquired weakness in critically ill patients

To test diagnostic accuracy of changes in thickness (TH) and cross-sectional area (CSA) of muscle ultrasound for diagnosis of intensive care unit acquired weakness (ICU-AW). Fully conscious patients were subjected to muscle ultrasonography including measuring the changes in TH and CSA of biceps brachii (BB) muscle, vastus intermedius (VI) muscle, and rectus femoris (RF) muscles over time. 37 patients underwent muscle ultrasonography on admission day, day 4, day 7, and day 10 after ICU admission, Among them, 24 were found to have ICW-AW. Changes in muscle TH and CSA of RF muscle on the right side showed remarkably higher ROC-AUC and the range was from 0.734 to 0.888. Changes in the TH of VI muscle had fair ROC-AUC values which were 0.785 on the left side and 0.779 on the right side on the 10th day after ICU admission. Additionally, Sequential Organ Failure Assessment (SOFA), Acute Physiology, and Chronic Health Evaluation II (APACHE II) scores also showed good discriminative power on the day of admission (ROC-AUC 0.886 and 0.767, respectively). Ultrasonography of changes in muscles, especially in the TH of VI muscle on both sides and CSA of RF muscle on the right side, presented good diagnostic accuracy. However, SOFA and APACHE II scores are better options for early ICU-AW prediction due to their simplicity and time efficiency.

New Approaches to Critical Illness Polyneuromyopathy: High-Resolution Neuromuscular Ultrasound Characteristics and Cytokine Profiling

Background

Diagnosis of intensive care unit acquired weakness (ICUAW) is challenging. Pathogenesis of underlying critical illness polyneuromyopathy (CIPNM) remains incompletely understood. This exploratory study investigated whether longitudinal neuromuscular ultrasound examinations and cytokine analyses in correlation to classical clinical and electrophysiological assessment contribute to the understanding of CIPNM.

Methods

Intensive care unit patients were examined every 7 days until discharge from hospital. Clinical status, nerve conduction studies, electromyography as well as ultrasound of peripheral nerves and tibial anterior muscle were performed. Cytokine levels were analyzed by a bead-based multiplex assay system.

Results

Of 248 screened patients, 35 patients were included at median of 6 days (IQR: 8) after admission to intensive care unit. Axonal damage was the main feature of CIPNM. At the peak of CIPNM (7 days after inclusion), nerve ultrasound showed cross-sectional area increase of tibial nerve as a sign of inflammatory edema as well as hypoechoic nerves as a possible sign of inflammation. Cytokine analyses showed signs of monocyte and macrophage activation at this stage. Fourteen days after inclusion, cytokines indicated systemic immune response as well as profiles associated to neovascularization and regeneration.

Conclusions

Exploratory neuromuscular ultrasound and cytokine analyses showed signs of inflammation like macrophage and monocyte activation at the peak of CIPNM followed by a systemic immune response parallel to axonal damage. This underlines the role of both axonal damage and inflammation in pathogenesis of CIPNM.

Electronic supplementary material

The online version of this article (10.1007/s12028-020-01148-2) contains supplementary material, which is available to authorized users.

Utility of Plasma GDF-15 for Diagnosis and Prognosis Assessment of ICU-Acquired Weakness in Mechanically Ventilated Patients: Prospective Observational Study

Objective

To identify the clinical correlations between plasma growth differentiation factor-15 (GDF-15), skeletal muscle function, and acute muscle wasting in ICU patients with mechanical ventilation. In addition, to investigate its diagnostic value for ICU-acquired weakness (ICU-AW) and its predictive value for 90-day survival in mechanically ventilated patients.

Methods

95 patients with acute respiratory failure, who required mechanical ventilation therapy, were randomly selected among hospitalized patients from June 2017 to January 2019. The plasma GDF-15 level was detected by ELISA, the rectus femoris cross-sectional area (RFcsa) was measured by ultrasound, and the patient's muscle strength was assessed using the British Medical Research Council (MRC) muscle strength score on day 1, day 4, and day 7. Patients were divided into an ICU-AW group and a non-ICU-AW group according to their MRC-score on the 7th day. The differences in plasma GDF-15 level, MRC-score, and RFcsa between the two groups were compared on the 1st, 4th, and 7th day after being admitted to the ICU. Then, the correlations between plasma GDF-15 level, RFcsa loss, and MRC-score on day 7 were investigated. The receiver operating characteristic curve (ROC) was used to analyze the plasma GDF-15 level, RFcsa loss, and % decrease in RFcsa on the 7th day to the diagnosis of ICU-AW in mechanically ventilated patients. Moreover, the predictive value of GDF-15 on the 90-day survival status of patients was assessed using patient survival curves.

Results

Based on whether the 7th day MRC-score was <48, 50 cases were included in the ICU-AW group and 45 cases in the non-ICU-AW group. The length of mechanical ventilation, ICU length of stay, and hospital length of stay were significantly longer in the ICU-AW group than in the non-ICU-AW group (all P < 0.05), while the other baseline indicators were not statistically significant between the two groups. As the treatment time increased, the plasma GDF-15 level was significantly increased, the ICU-AW group demonstrated a significant decreasing trend in the MRC-score and RFcsa, while no significant changes were found in the non-ICU-AW group. In the ICU-AW group, the plasma GDF-15 level was significantly higher than that in the non-ICU-AW group, while the RFcsa and the MRC-score were significantly lower than those in the non-ICU-AW group (GDF-15 (pg/ml): 2542.44 ± 629.38 vs. 1542.86 ± 502.86; RFcsa (cm²): 2.04 ± 0.64 vs. 2.34 ± 0.61; MRC-score: 41.22 ± 3.42 vs. 51.42 ± 2.72, all P < 0.05), while the other baseline indicators were not statistically significant between the two groups. As the treatment time increased, the plasma GDF-15 level was significantly increased, the ICU-AW group demonstrated a significant decreasing trend in the MRC-score and RFcsa, while no significant changes were found in the non-ICU-AW group. In the ICU-AW group, the plasma GDF-15 level was significantly higher than that in the non-ICU-AW group, while the RFcsa and the MRC-score were significantly lower than those in the non-ICU-AW group (GDF-15 (pg/ml): 2542.44 ± 629.38 vs. 1542.86 ± 502.86; RFcsa (cm²): 2.04 ± 0.64 vs. 2.34 ± 0.61; MRC-score: 41.22 ± 3.42 vs. 51.42 ± 2.72, all r = −0.60), while it was significantly positively correlated with the RFcsa loss (r = −0.60), while it was significantly positively correlated with the RFcsa loss (r = −0.60), while it was significantly positively correlated with the RFcsa loss (r = −0.60), while it was significantly positively correlated with the RFcsa loss (P < 0.05), while the other baseline indicators were not statistically significant between the two groups. As the treatment time increased, the plasma GDF-15 level was significantly increased, the ICU-AW group demonstrated a significant decreasing trend in the MRC-score and RFcsa, while no significant changes were found in the non-ICU-AW group. In the ICU-AW group, the plasma GDF-15 level was significantly higher than that in the non-ICU-AW group, while the RFcsa and the MRC-score were significantly lower than those in the non-ICU-AW group (GDF-15 (pg/ml): 2542.44 ± 629.38 vs. 1542.86 ± 502.86; RFcsa (cm²): 2.04 ± 0.64 vs. 2.34 ± 0.61; MRC-score: 41.22 ± 3.42 vs. 51.42 ± 2.72, all P < 0.05), while the other baseline indicators were not statistically significant between the two groups. As the treatment time increased, the plasma GDF-15 level was significantly increased, the ICU-AW group demonstrated a significant decreasing trend in the MRC-score and RFcsa, while no significant changes were found in the non-ICU-AW group. In the ICU-AW group, the plasma GDF-15 level was significantly higher than that in the non-ICU-AW group, while the RFcsa and the MRC-score were significantly lower than those in the non-ICU-AW group (GDF-15 (pg/ml): 2542.44 ± 629.38 vs. 1542.86 ± 502.86; RFcsa (cm²): 2.04 ± 0.64 vs. 2.34 ± 0.61; MRC-score: 41.22 ± 3.42 vs. 51.42 ± 2.72, all P < 0.05), while the other baseline indicators were not statistically significant between the two groups. As the treatment time increased, the plasma GDF-15 level was significantly increased, the ICU-AW group demonstrated a significant decreasing trend in the MRC-score and RFcsa, while no significant changes were found in the non-ICU-AW group. In the ICU-AW group, the plasma GDF-15 level was significantly higher than that in the non-ICU-AW group, while the RFcsa and the MRC-score were significantly lower than those in the non-ICU-AW group (GDF-15 (pg/ml): 2542.44 ± 629.38 vs. 1542.86 ± 502.86; RFcsa (cm²): 2.04 ± 0.64 vs. 2.34 ± 0.61; MRC-score: 41.22 ± 3.42 vs. 51.42 ± 2.72, all

Conclusion

The plasma GDF-15 concentration level was significantly associated with skeletal muscle function and muscle wasting on day 7 in ICU patients with mechanical ventilation. Therefore, it can be concluded that the plasma GDF-15 level on the 7th day has a high diagnostic yield for ICU-acquired muscle weakness, and it can predict the 90-day survival status of ICU mechanically ventilated patients.