Validation of an Artificial Intelligence-Based Ultrasound Imaging System for Quantifying Muscle Architecture Parameters of the Rectus Femoris in Disease-Related Malnutrition (DRM).

(1) Background: The aim was to validate an AI-based system compared to the classic method of reading ultrasound images of the rectus femur (RF) muscle in a real cohort of patients with disease-related malnutrition. (2) Methods: One hundred adult patients with DRM aged 18 to 85 years were enrolled. The risk of DRM was assessed by the Global Leadership Initiative on Malnutrition (GLIM). The variation, reproducibility, and reliability of measurements for the RF subcutaneous fat thickness (SFT), muscle thickness (MT), and cross-sectional area (CSA), were measured conventionally with the incorporated tools of a portable ultrasound imaging device (method A) and compared with the automated quantification of the ultrasound imaging system (method B). (3) Results: Measurements obtained using method A (i.e., conventionally) and method B (i.e., raw images analyzed by AI), showed similar values with no significant differences in absolute values and coefficients of variation, 58.39-57.68% for SFT, 30.50-28.36% for MT, and 36.50-36.91% for CSA, respectively. The Intraclass Correlation Coefficient (ICC) for reliability and consistency analysis between methods A and B showed correlations of 0.912 and 95% CI [0.872-0.940] for SFT, 0.960 and 95% CI [0.941-0.973] for MT, and 0.995 and 95% CI [0.993-0.997] for CSA; the Bland-Altman Analysis shows that the spread of points is quite uniform around the bias lines with no evidence of strong bias for any variable. (4) Conclusions: The study demonstrated the consistency and reliability of this new automatic system based on machine learning and AI for the quantification of ultrasound imaging of the muscle architecture parameters of the rectus femoris muscle compared with the conventional method of measurement.

The relationship between muscle thickness and pennation angle is mediated by fascicle length in the muscles of the lower extremities.

Muscle morphological architecture, a crucial determinant of muscle function, has fascinated researchers since the Renaissance. Imaging techniques enable the assessment of parameters such as muscle thickness (MT), pennation angle (PA), and fascicle length (FL), which may vary with growth, sex, and physical activity. Despite known interrelationships, robust mathematical models like causal mediation analysis have not been extensively applied to large population samples. We recruited 109 males and females, measuring knee flexor and extensor, and plantar flexor MT, PA, and FL using real-time ultrasound imaging at rest. A mixed-effects model explored sex, leg (dominant vs. non-dominant), and muscle region differences. Males exhibited greater MT in all muscles (0.1 to 2.1 cm, p < 0.01), with no sex differences in FL. Dominant legs showed greater rectus femoris (RF) MT (0.1 cm, p = 0.01) and PA (1.5°, p = 0.01), while vastus lateralis (VL) had greater FL (1.2 cm, p < 0.001) and PA (0.6°, p = 0.02). Regional differences were observed in VL, RF, and biceps femoris long head (BFlh). Causal mediation analyses highlighted MT's influence on PA, mediated by FL. Moderated mediation occurred in BFlh, with FL differences. Gastrocnemius medialis and lateralis exhibited FL-mediated MT and PA relationships. This study unveils the intricate interplay of MT, FL, and PA in muscle architecture.

Clinical evaluation of AI-assisted muscle ultrasound for monitoring muscle wasting in ICU patients.

Muscle ultrasound has been shown to be a valid and safe imaging modality to assess muscle wasting in critically ill patients in the intensive care unit (ICU). This typically involves manual delineation to measure the rectus femoris cross-sectional area (RFCSA), which is a subjective, time-consuming, and laborious task that requires significant expertise. We aimed to develop and evaluate an AI tool that performs automated recognition and measurement of RFCSA to support non-expert operators in measurement of the RFCSA using muscle ultrasound. Twenty patients were recruited between Feb 2023 and July 2023 and were randomized sequentially to operators using AI (n = 10) or non-AI (n = 10). Muscle loss during ICU stay was similar for both methods: 26 ± 15% for AI and 23 ± 11% for the non-AI, respectively (p = 0.13). In total 59 ultrasound examinations were carried out (30 without AI and 29 with AI). When assisted by our AI tool, the operators showed less variability between measurements with higher intraclass correlation coefficients (ICCs 0.999 95% CI 0.998-0.999 vs. 0.982 95% CI 0.962-0.993) and lower Bland Altman limits of agreement (± 1.9% vs. ± 6.6%) compared to not using the AI tool. The time spent on scans reduced significantly from a median of 19.6 min (IQR 16.9-21.7) to 9.4 min (IQR 7.2-11.7) compared to when using the AI tool (p < 0.001). AI-assisted muscle ultrasound removes the need for manual tracing, increases reproducibility and saves time. This system may aid monitoring muscle size in ICU patients assisting rehabilitation programmes.

Differences in Type 2 Fiber Composition in the Vastus Lateralis and Gluteus Maximus of Patients with Hip Fractures.

BACKGRUOUND: Aging leads to sarcopenia, which is characterized by reduced muscle mass and strength. Many factors, including altered muscle protein turnover, diminished neuromuscular function, hormonal changes, systemic inflammation, and the structure and composition of muscle fibers, play a crucial role in age-related muscle decline. This study explored differences in muscle fiber types contributing to overall muscle function decline in aging, focusing on individuals with hip fractures from falls. METHODS: A pilot study at Chungnam National University Hospital collected muscle biopsies from hip fracture patients aged 20 to 80 undergoing surgical treatment. Muscle biopsies from the vastus lateralis and gluteus maximus were obtained during hip arthroplasty or internal fixation. Handgrip strength, calf and thigh circumference, and bone mineral density were evaluated in individuals with hip fractures from falls. We analyzed the relationships between each clinical characteristic and muscle fiber type. RESULTS: In total, 26 participants (mean age 67.9 years, 69.2% male) were included in this study. The prevalence of sarcopenia was 53.8%, and that of femoral and lumbar osteoporosis was 19.2% and 11.5%, respectively. Vastus lateralis analysis revealed an age-related decrease in type IIx fibers, a higher proportion of type IIa fibers in women, and an association between handgrip strength and type IIx fibers in men. The gluteus maximus showed no significant correlations with clinical parameters. CONCLUSION: This study identified complex associations between age, sex, handgrip strength, and muscle fiber composition in hip fracture patients, offering insights crucial for targeted interventions combating age-related muscle decline and improving musculoskeletal health.

The Use of a Simple Vaginal Speculum to Harvest Quadriceps Tendon Autografts for Anterior Cruciate Ligament Reconstruction and Avoid Any Potential Pitfalls during Harvesting Procedure: Technical note.

This technical note aimed to present a straigthforward method for harvesting quadriceps tendon autografts with the use of a simple vaginal speculum and direct visualisation of a scope. Anterior cruciate ligament reconstruction with quadriceps tendon autografts has gained popularity in recent years, with many harvesting techniques that use different harvesting systems available on the market. These techniques vary from transverse to longitudinal skin incisions and from open to minimally invasive approaches and have a learning curve, as with the majority of surgical procedures. The technique proposed in this technical note is minimally invasive, can be easily reproduced by any surgeon irrespective of their experience, has a short learning curve, requires no additional cost or technical support during the procedure and creates a stable working space that allows for freedom of manipulation of surgical instruments and the arthroscope.

Effectiveness of the Copenhagen adduction modified position stage 1: EMG measurements and hand-held dynamometer analysis in young and healthy men.

OBJECTIVES: To verify the effectiveness of the use of a modified position of the Copenhagen Adduction (CA) stage 1 compared to the original position. DESIGN: Cross-sectional study. SETTING: Laboratory. PARTICIPANTS: 31 healthy men aged 23.7 ± 1.9 years with no recent or chronic general pathology. MAIN OUTCOME MEASURES: Differences between EMG amplitudes for the adductor longus (AL), rectus femoris (RF) and semi tendinous (ST) during dynamic contractions and adductor maximal isometric voluntary contraction (MIVC) force values between CA stage 1 standard and modified positions were assessed with either Wilcoxon or paired t-test. RESULTS: No significant differences were observed for EMG amplitudes of the AL (p-value = 0.724) and for the RF muscle (p-value = 0.337) and for the adductor force (p-value = 0.361) between the two positions. A significant difference was obtained for the ST (p-value<0.001) mainly explained by the adapted position of the non-dominant leg which unlocked the hip joint and generated less muscle activity in the hamstrings. CONCLUSIONS: Muscle activity of the AL muscle and adductor force being similar in both positions, the CA stage 1 modified position could be of interest for rehabilitation after adductor injury or strengthening of the adductors in elite athletes.

Effects of neuromuscular electrical stimulation on patellofemoral pain: A randomized controlled trial.

INTRODUCTION: Patellofemoral Pain (PFP) is a common dysfunction that can compromise the performance of daily activities. Neuromuscular electrical stimulation (NMES) has been proposed as a complementary tool in the therapeutic approach. OBJECTIVE: To analyze the effects of adding NMES to therapeutic exercises in women with PFP. METHODS: Randomized controlled trial involving 34 women with PFP (mean age 23.8 ± 4.1), randomly assigned to two groups: exercises combined with NMES (ESG) and exercises only (ExG). The ExG followed an exercise protocol, while the ESG performed the same exercises combined with NMES. Interventions were performed twice a week for eight weeks. Primary outcome measures included pain and functional disability, while secondary outcomes encompassed electromyographic activity of the quadriceps and hip abductors, along with isokinetic performance. Assessments were performed before the intervention, after 4 and 8 weeks from the start of the protocol and 8 weeks after the conclusion of the treatment. RESULTS: We did not observe difference between the groups in any of the analyzed variables. Both groups showed a reduction in pain and an improvement in functional disability during intragroup comparisons. CONCLUSION: A reduction in pain and an improvement in functional disability were observed; however, there was no additional effect of NMES. TRIAL REGISTRATION: NCT03918863.

Immediate effects of kinesiology tape on quadriceps muscle peak torque and knee joint repositioning error in healthy males: Effects of different tensions and directions.

BACKGROUND: Knee joint injuries may result from compromised quadriceps muscle strength or diminished knee joint proprioception. The application of Kinesio tape (KT) on the quadriceps muscle from origin to insertion (OTI-KT) or insertion to origin (ITO-KT) could impact knee joint proprioception and quadriceps muscle strength. This study aims to assess the effects of different tensions and directions of KT application on active and passive knee joint repositioning errors (AJRE and PJRE) and peak concentric and eccentric peak torque (CPT and EPT) of the quadriceps muscles in healthy males. METHOD: Twenty-one healthy males participated in this repeated-measures study design. CPT, EPT, AJRE, and PJRE of the dominant limb were measured by a Biodex dynamometer before and after applying OTI-KT with 0%, 15%, and 40% extra tensions and ITO-KT with 0% tension. RESULTS: ITO-KT demonstrated a significant reduction in AJRE (p < 0.05). Meanwhile, for OTI-KT, a statistically significant difference was observed in both AJRE and PJRE concerning time (F1,126 = 19.74, p < 0.05 for AJRE; F1,126 = 9.96, p < 0.05 for PJRE) and tension (F2,126 = 22.14, p < 0.05 for AJRE; F2,126 = 20.67, p < 0.05 for PJRE). CONCLUSION: Applying KT, especially OTI KT with 40% and 15% extra tension, shows potential in enhancing knee proprioception without immediate impacts on quadriceps muscle torque. This suggests applications in sports performance and knee injury rehabilitation.

Ultrasound Cut-Off Values for Rectus Femoris for Detecting Sarcopenia in Patients with Nutritional Risk.

BACKGROUND: A nationwide, prospective, multicenter, cohort study (the Disease-Related caloric-protein malnutrition EChOgraphy (DRECO) study) was designed to assess the usefulness of ultrasound of the rectus femoris for detecting sarcopenia in hospitalized patients at risk of malnutrition and to define cut-off values of ultrasound measures. METHODS: Patients at risk of malnutrition according to the Malnutrition Universal Screening Tool (MUST) underwent handgrip dynamometry, bioelectrical impedance analysis (BIA), a Timed Up and Go (TUG) test, and rectus femoris ultrasound studies. European Working Group on Sarcopenia in Older People (EWGSOP2) criteria were used to define categories of sarcopenia (at risk, probable, confirmed, severe). Receiver operating characteristic (ROC) and area under the curve (AUC) analyses were used to determine the optimal diagnostic sensitivity, specificity, and predictive values of cut-off points of the ultrasound measures for the detection of risk of sarcopenia and probable, confirmed, and severe sarcopenia. RESULTS: A total of 1000 subjects were included and 991 of them (58.9% men, mean age 58.5 years) were evaluated. Risk of sarcopenia was detected in 9.6% patients, probable sarcopenia in 14%, confirmed sarcopenia in 9.7%, and severe sarcopenia in 3.9%, with significant differences in the distribution of groups between men and women (p < 0.0001). The cross-sectional area (CSA) of the rectus femoris showed a significantly positive correlation with body cell mass of BIA and handgrip strength, and a significant negative correlation with TUG. Cut-off values were similar within each category of sarcopenia, ranging between 2.40 cm2 and 3.66 cm2 for CSA, 32.57 mm and 40.21 mm for the X-axis, and 7.85 mm and 10.4 mm for the Y-axis. In general, these cut-off values showed high sensitivities, particularly for the categories of confirmed and severe sarcopenia, with male patients also showing better sensitivities than women. CONCLUSIONS: Sarcopenia in hospitalized patients at risk of malnutrition was high. Cut-off values for the better sensitivities and specificities of ultrasound measures of the rectus femoris are established. The use of ultrasound of the rectus femoris could be used for the prediction of sarcopenia and be useful to integrate nutritional study into real clinical practice.

Effect of resistance training on quadriceps femoris muscle thickness obtained by ultrasound: A systematic review with meta-analysis.

OBJECTIVE: The present study aimed to determine the magnitude and intervention time of resistance training required to generate adaptations in the muscle thickness of the quadriceps muscle obtained by ultrasound in healthy adults. METHOD: A systematic review with meta-analysis was conducted on studies recovered from Pubmed, Web of Science, and Scopus databases up to March 2022. The study selection process was carried out by two independent researchers, with the presence of a third researcher in case of disagreements. The methodological quality of the studies was determined with the TESTEX scale, and the risk of bias analysis was determined using Cochrane's RoB 2.0 tool. The meta-analysis used the inverse of the variance with a fixed model, and the effect size was reported by the standardized mean difference (SMD) with a confidence interval of 95%. RESULTS: Ten studies were included in a meta-analysis. The overall analysis of the studies demonstrated an SMD = 0.35 [95% CI: 0.13-0.56] (P = 0.002), with a low heterogeneity of I2 = 0% (P = 0.52). No publication bias was detected using a funnel plot followed by Egger's test (P = 0.06). The degree of certainty of the meta-analysis was high using the GRADE tool. CONCLUSION: We found that resistance training can generate significant average increases of 16.6% in muscle thickness obtained by ultrasound in the quadriceps femoris muscles of healthy adults. However, the subgroup analysis showed that significant effect sizes were only observed after eight weeks of training.

Thigh muscle mass evaluated by point-of-care ultrasound is associated with short-term mortality in patients with sepsis in the emergency department.

Muscle mass depletion is associated with mortality and morbidity in various conditions including sepsis. However, few studies have evaluated muscle mass using point-of-care ultrasound in patients with sepsis. This study aimed to evaluate the association between thigh muscle mass, evaluated using point-of-care ultrasound with panoramic view in patients with sepsis in the emergency department, and mortality. From March 2021 to October 2022, this prospective observational study used sepsis registry. Adult patients who were diagnosed with sepsis at the emergency department and who underwent point-of-care ultrasounds for lower extremities were included. The thigh muscle mass was evaluated by the cross-sectional area of the quadriceps femoris (CSA-QF) on point-of-care ultrasound using panoramic view. The primary outcome was 28 day mortality. Multivariable Cox proportional hazard model was performed. Of 112 included patients with sepsis, mean CSA-QF was significantly lower in the non-surviving group than surviving group (49.6 [34.3-56.5] vs. 63.2 [46.9-79.6] cm2, p = 0.002). Each cm2 increase of mean CSA-QF was independently associated with decreased 28 day mortality (adjusted hazard ratio 0.961, 95% CI 0.928-0.995, p = 0.026) after adjustment for potential confounders. The result of other measurements of CSA-QF were similar. The muscle mass of the quadriceps femoris evaluated using point-of-care ultrasound with panoramic view was associated with mortality in patients with sepsis. It might be a promising tool for determining risk factors for mortality in sepsis patients in the early stages of emergency department.

The Duration of Non-Local Muscle Fatigue Effects.

Non-local muscle fatigue (NLMF) refers to a transient decline in the functioning of a non-exercised muscle following the fatigue of a different muscle group. Most studies examining NLMF conducted post-tests immediately after the fatiguing protocols, leaving the duration of these effects uncertain. The aim of this study was to investigate the duration of NLMF (1-, 3-, and 5-minutes). In this randomized crossover study, 17 recreationally trained participants (four females) were tested for the acute effects of unilateral knee extensor (KE) muscle fatigue on the contralateral homologous muscle strength, and activation. Each of the four sessions included testing at either 1-, 3-, or 5-minutes post-test, as well as a control condition for non-dominant KE peak force, instantaneous strength (force produced within the first 100-ms), and vastus lateralis and biceps femoris electromyography (EMG). The dominant KE fatigue intervention protocol involved two sets of 100-seconds maximal voluntary isometric contractions (MVIC) separated by 1-minute of rest. Non-dominant KE MVIC forces showed moderate and small magnitude reductions at 1-min (p < 0.0001, d = 0.72) and 3-min (p = 0.005, d = 0.30) post-test respectively. The KE MVIC instantaneous strength revealed large magnitude, significant reductions between 1-min (p = 0.021, d = 1.33), and 3-min (p = 0.041, d = 1.13) compared with the control. In addition, EMG data revealed large magnitude increases with the 1-minute versus control condition (p = 0.03, d = 1.10). In summary, impairments of the non-exercised leg were apparent up to 3-minutes post-exercise with no significant deficits at 5-minutes. Recovery duration plays a crucial role in the manifestation of NLMF.

Relationship between quadriceps muscle architecture and lower limb strength and physical function in older adults community-dwelling individuals: a cross-sectional study.

Background and objective: Factors related to muscle architecture may lead to functional limitations in activities of daily living in the older adults. This study aimed to investigate the relationship between quadriceps femoris (QF) architecture and physical function in older adults community-dwelling people. Methods: The study included 25 community-dwelling older adults participants aged over 60 years (14 women and 11 men) who were not engaged in regular physical activity. The rectus femoris (RF) and vastus intermedius (VI) muscle thicknesses as well as the RF cross-sectional area (CSA) were assessed using 2D ultrasonography. The 30 Seconds Chair Stand test (30sCST) and Timed Up and Go Test (TUG) were used to assess lower body muscle power and functional mobility, respectively. Results: The QF muscle architecture showed moderate and large correlations with the 30sCST (r range = 0.45-0.67, p < 0.05) and TUG (r range = 0.480-0.60, p < 0.05). RF thickness was a significant (p < 0.01) independent predictor of 30sCST (R 2 = 0.45) and TUG (R 2 = 0.36). VI thickness was a significant (p < 0.05) independent predictor of 30sCST (R 2 = 0.20) and TUG (R 2 = 0.231). RF CSA was a significant independent predictor of the 30sCST (R 2 = 0.250, p < 0.05) and TUG (R 2 = 0.27, p < 0.01). Multiple linear regression models explained 38% of the 30sCST variance and 30% of the TUG variance in the older adults group. Conclusion: Quadriceps muscle group directly affects basic activities of daily living in the older adults. Ultrasound measurements, which are non-invasive tools, are extremely valuable for understanding the limitations of activities of daily living in the older adults.

Neuromuscular Adaptations in Endurance-Trained Male Adolescents Versus Untrained Peers: A 9-Month Longitudinal Study.

BACKGROUND: Neuromuscular function is considered as a determinant factor of endurance performance during adulthood. However, whether endurance training triggers further neuromuscular adaptations exceeding those of growth and maturation alone over the rapid adolescent growth period is yet to be determined. OBJECTIVE: The present study investigated the concurrent role of growth, maturation, and endurance training on neuromuscular function through a 9-month training period in adolescent triathletes. METHODS: Thirty-eight 13- to 15-year-old males (23 triathletes [~6 h/week endurance training] and 15 untrained [<2 h/week endurance activity]) were evaluated before and after a 9-month triathlon training season. Maximal oxygen uptake (V̇O2max) and power at V̇O2max were assessed during incremental cycling. Knee extensor maximal voluntary isometric contraction torque (MVCISO) was measured and the voluntary activation level (VAL) was determined using the twitch interpolation technique. Knee extensor doublet peak torque (T100Hz) and normalized vastus lateralis (VL) electromyographic activity (EMG/M-wave) were also determined. VL and rectus femoris (RF) muscle architecture was assessed using ultrasonography. RESULTS: Absolute V̇O2max increased similarly in both groups but power at V̇O2max only significantly increased in triathletes (+13.8%). MVCISO (+14.4%), VL (+4.4%), and RF (+15.8%) muscle thicknesses and RF pennation angle (+22.1%) increased over the 9-month period in both groups similarly (p < 0.01), although no changes were observed in T100Hz, VAL, or VL EMG/M-wave. No changes were detected in any neuromuscular variables, except for coactivation. CONCLUSION: Endurance training did not induce detectible, additional neuromuscular adaptations. However, the training-specific cycling power improvement in triathletes may reflect continued skill enhancement over the training period.

A novel surgical technique for revision anterior cruciate ligament reconstruction using an isolated rectus femoris tendon autograft.

INTRODUCTION: Only a few anatomic studies have described an isolated rectus femoris tendon autograft for anterior cruciate ligament (ACL) reconstruction. This study aims to demonstrate a new surgical technique utilising the rectus femoris tendon for ACL reconstruction. This study hypothesises that the rectus tendon autograft will yield satisfying postoperative outcomes in terms of stability, with minimal complications at the harvest site. METHODS: This retrospective study investigated the outcomes of 28 revision ACL reconstructions using a rectus tendon autograft with a mean follow-up of 41.7 (range, 24.0-64.8) months. A 3 cm longitudinal incision was used to harvest the rectus tendon with an open tendon stripper. Intraoperative collected data included the length of the tendon and thickness of a 4-fold graft. Further outcome parameters include anterior cruciate ligament stability and range of motion. Additionally, postoperative complications, especially donor site morbidity, were documented in type and frequency. RESULTS: The mean tendon length measured 32.4 cm (range, 30-35 cm). After preparing a 4-fold graft, the mean diameter was 9.2 mm (range, 8.0-10 mm) at the tibial and 9.0 mm (range, 7.5-10 mm) at the femoral end. Stability evaluated by the Lachman test improved significantly from 2 (Interquartile range (IQR), 2-3) preoperatively to 0 (IQR, 0-1) postoperatively (p < .001). Rerupture of the anterior cruciate ligament graft was observed in 2 patients (7.1%). Four patients showed a persistent extension deficit of about 5 degrees postoperatively. Two of them underwent revision surgery due to a Cyclops lesion. Only one patient complained of prolonged pain at the harvest site (3.6%). CONCLUSION: The 4-fold rectus tendon represents a novel autograft technique in revision ACL reconstruction. This study provides evidence of appropriate graft dimensions and satisfying postoperative outcomes regarding stability. The technique is associated with a low complication rate at the harvest site. STUDY DESIGN: Case series; Level of evidence, IV.

Physiologic Determinants of Near-Infrared Spectroscopy-Derived Cerebral and Tissue Oxygen Saturation Measurements in Critically Ill Patients.

OBJECTIVES: Near-infrared spectroscopy (NIRS) is a potentially valuable modality to monitor the adequacy of oxygen delivery to the brain and other tissues in critically ill patients, but little is known about the physiologic determinants of NIRS-derived tissue oxygen saturations. The purpose of this study was to assess the contribution of routinely measured physiologic parameters to tissue oxygen saturation measured by NIRS. DESIGN: An observational sub-study of patients enrolled in the Role of Active Deresuscitation After Resuscitation-2 (RADAR-2) randomized feasibility trial. SETTING: Two ICUs in the United Kingdom. PATIENTS: Patients were recruited for the RADAR-2 study, which compared a conservative approach to fluid therapy and deresuscitation with usual care. Those included in this sub-study underwent continuous NIRS monitoring of cerebral oxygen saturations (SctO2) and quadriceps muscle tissue saturations (SmtO2). INTERVENTION: Synchronized and continuous mean arterial pressure (MAP), heart rate (HR), and pulse oximetry (oxygen saturation, Spo2) measurements were recorded alongside NIRS data. Arterial Paco2, Pao2, and hemoglobin concentration were recorded 12 hourly. Linear mixed effect models were used to investigate the association between these physiologic variables and cerebral and muscle tissue oxygen saturations. MEASUREMENTS AND MAIN RESULTS: Sixty-six patients were included in the analysis. Linear mixed models demonstrated that Paco2, Spo2, MAP, and HR were weakly associated with SctO2 but only explained 7.1% of the total variation. Spo2 and MAP were associated with SmtO2, but together only explained 0.8% of its total variation. The remaining variability was predominantly accounted for by between-subject differences. CONCLUSIONS: Our findings demonstrated that only a small proportion of variability in NIRS-derived cerebral and tissue oximetry measurements could be explained by routinely measured physiologic variables. We conclude that for NIRS to be a useful monitoring modality in critical care, considerable further research is required to understand physiologic determinants and prognostic significance.

Hamstrings-quadriceps strength ratio could be related to falls in community-living older adults.

A prior study reported that the concentric strength imbalance between hamstrings and quadriceps is associated with falls in older adults. Given that the concentric strength may not be measured as conveniently as the isometric strength, it is meaningful to test whether the isometric hamstring-quadricep strength imbalance is related to falls among older adults. This study sought to explore whether the hamstrings-quadriceps ratio could differentiate fallers from non-fallers in community-dwelling older adults. One hundred and eleven older adults were included in this cross-sectional study. Their isometric knee joint strength capacity (extensors and flexors) was measured. Based on their fall history in the past year, they were classified as fallers (at least one fall) or non-fallers (no fall). The hamstrings-quadriceps ratio was compared between the faller and non-faller groups. The receiver operating characteristic analysis was used to determine the cutoff value of the hamstrings-quadriceps ratio able to best classify fallers and non-fallers. Fallers showed a significantly lower hamstrings-quadriceps ratio than non-fallers (p = 0.008). The receiver operating characteristic analysis identified 0.733 as the best ratio to differentiate fallers from non-fallers with an accuracy of 64.0 %. A 0.1-unit reduction in the hamstrings-quadriceps ratio increases the probability of falling by a factor of 1.30. The hamstrings-quadriceps ratio could be used as an additional fall risk factor when assessing the risk of falls among older adults. A smaller than 0.733 hamstring-quadriceps ratio may indicate a high risk of falls.

Indirect calorimetry directed feeding and cycling in the older ICU population: a pilot randomised controlled trial.

BACKGROUND: Older critically ill patients experience rapid muscle loss during stay in an intensive care unit (ICU) due to physiological stress and increased catabolism. This may lead to increased ICU length of stay, delayed weaning from ventilation and persistent functional limitations. We hypothesized that with optimal nutrition and early physical therapy acting in synergism, we can reduce muscle mass loss and improve functional outcomes. METHODS: This was a prospective, single blinded randomized, controlled single-center pilot study to compare the lean muscle mass (measured at bilateral quadriceps femoris using ultrasound) of older ICU patients at 4 time points over 14 days between the control and intervention groups. The control group received standard weight-based empiric feeding and standard ICU physiotherapy. The intervention group received indirect calorimetry directed feeding adjusted daily and 60 min per day of cycle ergometry. 21 patients were recruited and randomized with 11 patients in the control arm and 10 patients in the intervention arm. Secondary outcome measures included ICU and hospital mortality, length of stay, functional assessments of mobility and assessment of strength. RESULTS: Median age was 64 in the control group and 66 in the intervention group. Median calories achieved was 24.5 kcal/kg per day in the control group and 23.3 kcal/kg per day in the intervention group. Cycle ergometry was applied to patients in the intervention group for a median of 60 min a day and a patient had a median of 8.5 sessions in 14 days. Muscle mass decreased by a median of 4.7cm2 in the right quadriceps femoris in the control group and 1.8cm2 in the intervention group (p = 0.19), while the left quadriceps femoris decreased by 1.9cm2 in the control group and 0.1cm2 in the intervention group (p = 0.51). CONCLUSION: In this pilot study, we found a trend towards decrease muscle loss in bilateral quadriceps femoris with our combined interventions. However, it did not reach statistical significance likely due to small number of patients recruited in the study. However, we conclude that the intervention is feasible and potentially beneficial and may warrant a larger scale study to achieve statistical significance. TRIAL REGISTRATION: This study was registered on Clinicaltrials.gov on 30th May 2018 with identifier NCT03540732.