Muscle strength measurement in the intensive care unit: not everything that can be counted counts

Reproducibility and agreement between three positions for handgrip assessment

The protocol established for taking hand grip dynamometry measurements determines that the patient must be in a sitting position. This protocol cannot be applied due to the patient’s conditions in some cases, such as abdominal surgery, musculoskeletal spine or hip injuries. The purpose was to determine the reproducibility and level of agreement between the Handgrip dynamometry in supine position with the elbow flexed or extended, and the one measured in the sitting position, the design was a descriptive cross-sectional study. The population were young apparently healthy between 18 and 30 years of age (N = 201). Handgrip measurement was performed on both upper limbs in a sitting position with a flexed elbow, a supine position with a flexed elbow, and supine position with the elbow extended. Reproducibility was nearly perfect in all positions (ICC 0.95–0.97). Regarding the level of agreement for the comparison between sitting and supine positions with a flexed elbow, an average difference of − 0.406. For supine position with an extended elbow and supine position with a flexed elbow, the average difference was − 1.479. Considering the results, clinicians or researchers can choose any of the positions evaluated herein and obtain reliable results as long as the standardization process is followed.

Functional ability and quality of life in critical illness survivors with intensive care unit acquired weakness: A secondary analysis of a randomised controlled trial

Introduction

Intensive care unit acquired weakness (ICUAW) may contribute to functional disability in ICU survivors, yet performance-based data for general ICU patients are lacking. This study explored functional outcomes of (1) and risk factors for (2) weakness at ICU discharge.

Methods

Data from a randomised controlled trial that investigated two early exercise regimes in previously independent, ventilated adults (n = 115) without any significant outcome-differences were used for the present analysis. ICUAW was clinically diagnosed in cooperative participants (n = 83) at ICU discharge with the Medical Research Council sum-score (MRC-SS) using a cut-off <48 for moderate or <36 for severe weakness. Primary outcomes were the 6-Minute Walk Test and Functional Independence Measure at hospital discharge. Secondary outcomes included health-related quality of life after six months. Risk factors during the ICU stay were explored for their effect on MRC-SS with linear regression.

Results

Functional outcomes and length of hospital stay significantly differed in patients with severe, moderate to no weakness (6-Minute Walk test: p = 0.013; 110m [IQR 75–240], 196m [90–324.25], 222.5m [129–378.75], Functional Independence Measure: p = 0.001; 91[IQR 68–101], 113[102.5–118.5], 112[97–123], length of stay after ICU discharge: p = 0.008; 20.9d [IQR 15.83–30.73], 16.86d [13.07–27.10], 11.16d [7.35–19.74]). However, after six months participants had similar values for quality of life regardless of their strength at ICU discharge (Short-Form 36 sum-scores physical health: p = 0.874, mental health: p = 0.908). In-bed immobilisation was the most significant factor associated with weakness at ICU discharge in the regression models (MRC-SS: -24.57(95%CI [-37.03 to -12.11]); p<0.001).

Conclusions

In this general, critically ill cohort, weakness at ICU discharge was associated with short-term functional disability and prolonged hospital length of stay, but not with quality of life, which was equivalent to the values for patients without ICUAW within six months. Immobilisation may be a modifiable risk factor to prevent ICUAW. Prospective trials are needed to validate these results.

Trial registration

German Clinical Trials Register (DRKS) identification number: DRKS00004347, registered on September 10, 2012.

Relevance to assess and preserve muscle strength in aging field

According to the revised European consensus on sarcopenia, muscle strength is the primary parameter of sarcopenia and is associated with adverse outcomes or physical limitation. This literature review aims to clarify how and why to measure and preserve muscle strength in older population. Overall, the relationship between muscle strength and physical function is impacted by level of muscle mass, the degree of obesity (BMI), age and physical activity. Therefore, these factors are to be considered in the evaluation of muscle strength. It is necessary to have objective, reliable and sensitive tools to assess muscle strength, in different populations to detect and quantify weakness, to adapt physical exercises to patients' capacity and to evaluate the effects of treatment. Handgrip strength measurement might be reasonable for clinical practice while the measurement of knee flexors/extensors strength with both 1RM and dynamometers is increasingly important yet restricted by the requirement of special equipment. Physical activity and nutrition are two important behavioral factors to maintain muscle strength. Combined exercise and nutrition interventions improved muscle strength to a more prominent degree than exercise or nutrition alone.

Clinical review: peripheral muscular ultrasound in the ICU

Muscular weakness developing from critical illness neuropathy, myopathy and muscle atrophy has been characterized as intensive care unit-acquired weakness (ICUAW). This entity occurs commonly during and after critical care stay. Various causal factors for functional incapacity have been proposed. Among these, individual patient characteristics (such as age, comorbidities and nutritional status), acting in association with sustained bed rest and pharmacological interventions (included the metabolic support approach), seem influential in reducing muscular mass. Long-term outcomes in heterogeneous ICUAW populations include transient disability in 30% of patients and persistent disabilities that may occur even in patients with nearly complete functional recovery. Currently available tools for the assessment of skeletal muscle mass are imprecise and difficult to perform in the ICU setting. A valid alternative to these imaging modalities is muscular ultrasonography, which allows visualization and classification of muscle characteristics by cross-sectional area, muscle layer thickness, echointensity by grayscale and the pennation angle). The aim of this narrative review is to describe the current literature addressing muscular ultrasound for the detection of muscle weakness and its potential impact on treatment and prognosis of critically ill patients when combined with biomarkers of muscle catabolism/anabolism and bioenergetic state. In addition, we suggest a practical flowchart for establishing an early diagnosis.

Influence of muscle strength on early mobility in critically ill adult patients: Systematic literature review

BACKGROUND

Muscle strength may be one indicator of readiness to mobilize that can be used to guide decisions regarding early mobility efforts and to progressively advance mobilization.

OBJECTIVES

To provide a synthesis of current measures of muscle strength in the assessment of early mobilization in critically ill adult patients who are receiving MV therapy.

METHODS

Research studies conducted between 2000-2015 were identified using PubMed, CINHAL, MEDLINE, and the Cochrane Database of Systematic Reviews databases using the search terms "muscle strength", "intensive care", "mechanical ventilation" and "muscle weakness".

RESULTS

Nine articles used manual muscle testing, the Medical Research Council scale and/or hand-held dynamometer to provide objective measures for assessing muscle strength in the critically ill adult patient population.

CONCLUSIONS

Further research is needed to examine the application of standardized measures of muscle strength for guiding decisions regarding early and progressive advancement of mobility goals in adult ICU patients on MV.

Measurement of muscle strength with handheld dynamometer in Intensive Care Unit

BACKGROUND

Intensive Care Unit (ICU) acquired weakness is a common complication in critically ill patients affecting their prognosis. The handheld dynamometry is an objective method in detecting minimum muscle strength change, which has an impact on the physical function of ICU survivors. The minimal change in the force can be measured in units of weight such as pounds or kilograms.

AIM OF THE STUDY

To detect the changes in peripheral muscle strength with handheld dynamometer in the early stage of ICU stay and to observe the progression of muscle weakness.

METHODOLOGY

Three upper and three lower limb muscles force measured with handheld dynamometer during ICU stay. Data were analyzed using repeated measures ANOVA to detect changes in force generated by muscle on alternate days of ICU stay.

RESULTS

There was a reduction in peripheral muscle strength from day 3 to day 5 as well from day 5 to day 7 of ICU stay (P < 0.01). The average reduction in peripheral muscle strength was 11.8% during ICU stay.

CONCLUSION

This study showed a progressive reduction in peripheral muscle strength as measured by handheld dynamometer during early period of ICU stay.

Acquired Muscle Weakness in the Surgical Intensive Care Unit

Muscle weakness is common in the surgical intensive care unit (ICU). Low muscle mass at ICU admission is a significant predictor of adverse outcomes. The consequences of ICU-acquired muscle weakness depend on the underlying mechanism. Temporary drug-induced weakness when properly managed may not affect outcome. Severe perioperative acquired weakness that is associated with adverse outcomes (prolonged mechanical ventilation, increases in ICU length of stay, and mortality) occurs with persistent (time frame: days) activation of protein degradation pathways, decreases in the drive to the skeletal muscle, and impaired muscular homeostasis. ICU-acquired muscle weakness can be prevented by early treatment of the underlying disease, goal-directed therapy, restrictive use of immobilizing medications, optimal nutrition, activating ventilatory modes, early rehabilitation, and preventive drug therapy. In this article, the authors review the nosology, epidemiology, diagnosis, and prevention of ICU-acquired weakness in surgical ICU patients.

In-Bed Mobilization in Critically Ill Children: A Safety and Feasibility Trial

The objective of this study was to evaluate the feasibility and safety of implementing two methods of in-bed mobilization in critically ill children. This prospective cohort trial was conducted at McMaster Children's Hospital, Pediatric Critical Care Unit (PCCU). Hemodynamically stable patients aged 3 to 17 years with a longer than 24-hour PCCU stay were eligible to participate in the study. Children with cardiorespiratory instability, already mobilizing well or at their baseline mobility, anticipated death during this PCCU admission, and those with contraindications to mobilization were excluded. Two methods of mobilization were applied for a maximum of 2 days, respectively, depending on the level of consciousness and cognitive ability of the participant. In-bed cycling was used for passive mobilization and interactive video games (VG) were used for active mobilization. The primary outcomes were safety and feasibility. Secondary outcomes were physical activity during the study period, as reflected by accelerometer measurements. A total of 406 patients were screened over 1 year, 35 of who were eligible and 31 (89%) consented to participate. Median age of participants was 11 years (quartile 1 is 6 years and quartile 3 is 14 years), and 15 (48%) were male. Twenty-five (81%) participants received the study intervention, 22 (88%) of who received the intervention within 24 hours of consent. Twenty-one (84%) participants received in-bed cycling, five (20%) received VG, and only one received both. Fifteen (60%) completed the prescribed 2-day intervention, while in 11 (44%) the intervention was interrupted or not applied, most commonly because the patient was transferred out of the PCCU. Physical activity was greater during the intervention compared with nonintervention times with in-bed cycling, but not with VG. There were no adverse events attributable to the intervention. This pilot reveals that in-bed cycling can enhance physical activity, and appears to be safe and feasible in this group of critically ill children. VG was feasible only in a minority of patients who were cooperative and age appropriate. Further research is necessary to evaluate the efficacy and most appropriate methods of enhancing mobility and rehabilitation in this population.

Feasibility and Reliability of Muscle Strength Testing in Critically Ill Children

Diagnosing pediatric intensive care unit-acquired weakness (PICU-AW) is challenging. The Medical Research Council (MRC) score is a widely used screening method for muscle weakness in critically ill adults; however, its utility in critically ill children has not been established. Our objective was to determine the feasibility and interobserver reliability of muscle strength testing using MRC score in critically ill children. A prospective observational substudy of critically ill children aged 1 to 17 years and limited to bed rest during the first 48 hours of PICU admission was evaluated with weekly MRC exams independently performed by two clinical raters. MRC exams were attempted on all 33 participants, but could be completed in only 21 (64%), 9 of who (43%) received at least one exam while in the PICU, and in the remaining 12 (57%), MRC exams could only be completed after PICU discharge. Of the 95 attempted MRC exams, 55 (57%) could not be conducted or completed, most commonly due to patient sedation, and inability to comply due to cognitive ability, pain, or noncooperation. The inter-rater reliability for MRC sum score was excellent (intraclass correlation coefficient: 0.87). However, the inter-rater reliability was only moderate when used to determine PICU-AW (Cohen kappa: 0.48). MRC testing in the PICU was not feasible as an early screening tool for muscle weakness in the majority of critically ill children in this study. Further research is needed to find an appropriate screening tool that is both feasible and predicts clinically relevant outcomes in children, such as function and recovery following critical illness.