EEG Correlates of Central Origin of Cancer-Related Fatigue.

The neurophysiological mechanism of cancer-related fatigue (CRF) remains poorly understood. EEG was examined during a sustained submaximal contraction (SC) task to further understand our prior research findings of greater central contribution to early fatigue during SC in CRF. Advanced cancer patients and matched healthy controls performed an elbow flexor SC until task failure while undergoing neuromuscular testing and EEG recording. EEG power changes over left and right sensorimotor cortices were analyzed and correlated with brief fatigue inventory (BFI) score and evoked muscle force, a measure of central fatigue. Brain electrical activity changes during the SC differed in CRF from healthy subjects mainly in the theta (4-8 Hz) and beta (12-30 Hz) bands in the contralateral (to the fatigued limb) hemisphere; changes were correlated with the evoked force. Also, the gamma band (30-50 Hz) power decrease during the SC did not return to baseline after 2 min of rest in CRF, an effect correlated with BFI score. In conclusion, altered brain electrical activity during a fatigue task in patients is associated with central fatigue during SC or fatigue symptoms, suggesting its potential contribution to CRF during motor performance. This information should guide the development and use of rehabilitative interventions that target the central nervous system to maximize function recovery.

United States Registered Nurse Workforce Report Card and Shortage Forecast.

Registered nurses (RNs) play a critical role in health care delivery. With an aging US population, health care demand is growing at an unprecedented pace. Using projected changes in population size and age, the authors developed demand and supply models to forecast the RN job shortage in each of the 50 states. Letter grades were assigned based on projected RN job shortage ratios. The number of states receiving a grade of "D" or "F" for their RN shortage ratio will increase from 5 in 2009 to 30 by 2030, for a total national deficit of 918 232 (725 619 - 1 112 112) RN jobs. There will be significant RN workforce shortages throughout the country in 2030; the western region will have the largest shortage ratio of 389 RN jobs per 100 000. Increased efforts to understand shortage dynamics are warranted.

Functional Corticomuscular Signal Coupling Is Weakened during Voluntary Motor Action in Cancer-Related Fatigue.

Background and Purpose: Cancer-related fatigue (CRF) is widely recognized as one of the most common symptoms and side effects of cancer and/or its treatment. However, neuropathological mechanisms contributing to CRF are largely unknown, and the lack of knowledge makes CRF difficult to treat. Recent research has shown dissociation between changes in the brain and muscle signals during voluntary motor performance in cancer survivors with CRF, and this dissociation may be caused by an interruption in functional coupling (FC) of the two signals. The goal of this study was to assess the FC between EEG (cortical signal) and EMG (muscular signal) in individuals with CRF and compare the FC with that of healthy controls during a motor task that led to progressive muscle fatigue. Method: Eight cancer survivors with CRF and nine healthy participants sustained an isometric elbow flexion contraction (at 30% maximal level) until self-perceived exhaustion. The entire duration of the EEG and EMG recordings was divided into the first-half (less-fatigue stage) and second-half (more-fatigue stage) artifact-free epochs without overlapping. The EEG-EMG coupling (measured by coherence of the two signals) in each group and stage was computed. Coherence values at different frequencies were statistically analyzed using a repeated-measure general linear model. Results: The results demonstrated that compared to healthy controls, CRF participants sustained the contraction for a significantly shorter time and exhibited robust and significantly lower EEG-EMG coherence at the alpha (8~14 Hz) and beta (15~35 Hz) frequency bands. Both the CRF and healthy control groups exhibited significantly decreased EEG-EMG coherence from the less-fatigue to more-fatigue stages at the alpha and beta frequency bands, indicating fatigue-induced weakening of functional corticomuscular coupling. Conclusion: Impaired functional coupling between the brain and muscle signals could be a consequence of cancer and/or its treatment, and it may be one of the contributing factors to the abnormal feeling of fatigue that caused the early failure of sustaining a prolonged motor task.

Sacral skin blood flow response to alternating pressure operating room overlay.

Pressure injuries resulting from long surgeries may be caused by prolonged ischemia. Operating table surfaces with alternating pressure (AP) features may reduce the risk of ischemia-induced pressure injuries by providing periodic relief of blood flow occlusions. Prior research investigated alternating loading applied with a single isolated rigid indenter and demonstrated increased perfusion. This study quantified effects of an overlay with AP on sacral skin perfusion for individuals lying supine for 60-min while blood flow was monitored. The mean normalized sacral skin blood flow was found to be greater with the AP overlay over an operating table pad compared to the operating pad alone (pad with AP mean SBF = 1.45 ±â€¯1.16, pad without AP mean SBF = 1.03 ±â€¯0.46, p = 0.10). Peak and average interface pressure at the sacrum was significantly lower during the deflation cycle of the AP surface compared to the operating pad alone (P < 0.001), suggesting this periodic reduction resulted in higher mean blood flow. Post-hoc regression analysis showed participant body mass index was a significant predictor of the effectiveness of the AP overlay (p = 0.012). The results suggest risk for pressure injuries due to prolonged ischemia might be mitigated by the addition of an alternating pressure feature on operating table pads for lower BMI patients.

The level of effort, rather than muscle exercise intensity determines strength gain following a six-week training.

AIM: This study investigated the effect of voluntary motor effort during a low-intensity (30% maximal voluntary contraction [MVC]) muscle exercise training program on increasing muscle strength. MATERIALS AND METHODS: Eighteen young and healthy individuals were randomly assigned to one of three groups: high mental effort (HME), low mental effort (LME), or a no-training control (CTRL) group. Training lasted for 6weeks (15min/day, 5days/week). The participants' right-elbow flexor muscle strength was measured before and after the training program. KEY FINDINGS: After training, the HME group gained 20.47±8.33% (P=0.01) strength while the LME and CTRL groups had negligible strength changes (1.89±0.96% and -3.27±2.61%, respectively; P>0.05) despite muscle contraction intensity (30% MVC) sustained during training was the same for the HME and LME groups. These results suggest that the level of effort involved in resistance exercise training plays a critical role in determining the amount of strength augmentation. SIGNIFICANCE: The finding that high effort combined with low-level physical exercise training can significantly increase muscle strength has rehabilitation applications as many patients and frail older adults have difficulties in participating in high-intensity exercise training such as lifting heavy weights. High effort plus low-level muscle exercise might serve as a safe training regimen for effective muscle strengthening in vulnerable populations.

Motor effort training with low exercise intensity improves muscle strength and descending command in aging.

This study explored the effect of high mental effort training (MET) and conventional strength training (CST) on increasing voluntary muscle strength and brain signal associated with producing maximal muscle force in healthy aging. Twenty-seven older adults (age: 75 ±â€Š7.9 yr, 8 women) were assigned into 1 of 3 groups: MET group-trained with low-intensity (30% maximal voluntary contraction [MVC]) physical exercise combined with MET, CST group-trained with high-intensity muscle contractions, or control (CTRL) group-no training of any kind. MET and CST lasted for 12 weeks (5 sessions/week). The participants' elbow flexion strength of the right arm, electromyography (EMG), and motor activity-related cortical potential (MRCP) directly related to the strength production were measured before and after training. The CST group had the highest strength gain (17.6%, P <0.001), the MET group also had significant strength gain (13.8%, P <0.001), which was not statistically different from that of the CST group even though the exercise intensity for the MET group was only at 30% MVC level. The CTRL group did not have significant strength changes. Surprisingly, only the MET group demonstrated a significant augmentation in the MRCP (29.3%, P <0.001); the MRCP increase in CST group was at boarder-line significance level (12.11%, P = 0.061) and that for CTRL group was only 4.9% (P = 0.539). These results suggest that high mental effort training combined with low-intensity physical exercise is an effective method for voluntary muscle strengthening and this approach is especially beneficial for those who are physically weak and have difficulty undergoing conventional strength training.

Are CMS G-Code Functional Limitation Severity Modifiers Responsive to Change Across an Episode of Outpatient Rehabilitation?

BACKGROUND: The Centers for Medicare & Medicaid Services has mandated rehabilitation professionals to document patients' impairment levels. There is no evidence of responsiveness to change of functional limitation severity modifier codes. OBJECTIVE: The purpose of this study was to assess the validity of G-code functional limitation severity modifier codes in determining change in function. DESIGN: This was a retrospective observational study. METHODS: Patients completed the Activity Measure for Post-Acute Care (AM-PAC) and were assigned G-codes, with severity modifiers based on AM-PAC scores at initial and follow-up visits. Patients were classified as having AM-PAC scores in the upper or lower range for each severity modifier, and sensitivity, specificity, and positive and negative predictive values for change in severity modifier level and odds of changing by one severity modifier level using a change in AM-PAC score of at least 1 minimal detectable change at the 95% confidence interval (MDC95) as the standard were determined. RESULTS: Sensitivity and specificity of change in severity modifier in determining change in function were dependent on patients' initial AM-PAC scores. Improvement in severity modifier level was 2.2 to 4.5 times more likely with scores at the higher end of the range within a severity modifier level than with scores in the lower end of the range. Decline in severity modifier level was 2.7 to 4.8 times more likely with scores at the lower end of the range within a severity modifier than with scores in the higher end of the range. LIMITATIONS: Data were from one health care system, and most patients had orthopedic conditions. The MDC95 for AM-PAC tool may not be the best standard for defining functional change. CONCLUSIONS: The G-code functional limitation severity modifier system may not be valid for determining change in function and is not recommended for determining if patients have changed over the course of outpatient therapy.

Interrater Reliability of AM-PAC "6-Clicks" Basic Mobility and Daily Activity Short Forms.

BACKGROUND: The interrater reliability of 2 new inpatient functional short-form measures, Activity Measure for Post-Acute Care (AM-PAC) "6-Clicks" basic mobility and daily activity scores, has yet to be established. OBJECTIVE: The purpose of this study was to examine the interrater reliability of AM-PAC "6-Clicks" measures. DESIGN: A prospective observational study was conducted. METHODS: Four pairs of physical therapists rated basic mobility and 4 pairs of occupational therapists rated daily activity of patients in 1 of 4 hospital services. One therapist in a pair was the primary therapist directing the assessment while the other therapist observed. Each therapist was unaware of the other's AM-PAC "6-Clicks" scores. Reliability was assessed with intraclass correlation coefficients (ICCs), Bland-Altman plots, and weighted kappa. RESULTS: The ICCs for the overall reliability of basic mobility and daily activity were .849 (95% confidence interval [CI]=.784, .895) and .783 (95% CI=.696, .847), respectively. The ICCs for the reliability of each pair of raters ranged from .581 (95% CI=.260, .789) to .960 (95% CI=.897, .983) for basic mobility and .316 (95% CI=-.061, .611) to .907 (95% CI=.801, .958) for daily activity. The weighted kappa values for item agreement ranged from .492 (95% CI=.382, .601) to .712 (95% CI=.607, .816) for basic mobility and .251 (95% CI=.057, .445) to .751 (95% CI=.653, .848) for daily activity. Mean differences between raters' scores were near zero. LIMITATIONS: Raters were from one health system. Each pair of raters assessed different patients in different services. CONCLUSIONS: The ICCs for AM-PAC "6-Clicks" total scores were very high. Levels of agreement varied across pairs of raters, from large to nearly perfect for physical therapists and from moderate to nearly perfect for occupational therapists. Levels of agreement for individual item scores ranged from small to very large.

Evidence of significant central fatigue in patients with cancer-related fatigue during repetitive elbow flexions till perceived exhaustion.

OBJECTIVE: To investigate whether fatigue induced by an intermittent motor task in patients with cancer-related fatigue (CRF) is more central or peripheral. METHODS: Ten patients with CRF who were off chemo and radiation therapies and 14 age-matched healthy controls were enrolled. Participants completed a Brief Fatigue Inventory (BFI) and performed a fatigue task consisting of intermittent elbow-flexion contractions at submaximal (40% maximal voluntary contraction) intensity till self-perceived exhaustion. Twitch force was elicited by an electrical stimulation applied to the biceps brachii muscle. The relative degree of peripheral (muscle) vs. central contribution to fatigue induced by the intermittent motor task (IMT) was assessed using twitch force ratio (TF ratio) defined as post IMT twitch force to pre IMT twitch force. The total number of trials (intermittent contractions) and total duration of all trials performed by each subject were also quantified. RESULTS: BFI scores were higher (p < 0.001) in CRF than controls, indicating greater feeling of fatigue in CRF patients than controls. A significantly smaller number of trials and shorter total duration of the trials (p < 0.05) were observed in CRF than control participants. The TF ratio (0.81 ± 0.05) in CRF was higher (p < 0.05) compared with that of controls (0.62 ± 0.05), suggesting CRF patients experienced a significantly lower degree of muscle (peripheral) fatigue at the time of perceived exhaustion. CONCLUSION: Consistent with prior findings for fatigue under submaximal sustained contraction, our results indicate that motor fatigue in CRF is more of central than peripheral origin during IMT. Significant central fatigue in CRF patients limits their ability to prolong motor performance.

AM-PAC "6-Clicks" functional assessment scores predict acute care hospital discharge destination.

BACKGROUND: Physical therapists and occupational therapists practicing in acute care hospitals play a crucial role in discharge planning. A standardized assessment of patients' function could be useful for discharge recommendations. OBJECTIVES: The study objective was to determine the accuracy of "6-Clicks" basic mobility and daily activity measures for predicting discharge from an acute care hospital to a home or institutional setting. DESIGN: The study was retrospective and observational. METHODS: "6-Clicks" scores obtained at initial visits by physical therapists or occupational therapists and patients' discharge destinations were used to develop and validate receiver operating characteristic curves for predicting discharge destination. Positive predictive values (PPV), negative predictive values (NPV), and likelihood ratios were calculated. RESULTS: Areas under the receiver operating characteristic curves for basic mobility scores were 0.857 (95% confidence interval [CI]=0.852, 0.862) and 0.855 (95% CI=0.850, 0.860) in development and validation samples, respectively. Areas under the curves for daily activity scores were 0.846 (95% CI=0.841, 0.851) and 0.845 (95% CI=0.840, 0.850) in development and validation samples, respectively. Cutoff scores providing the best accuracy for determining discharge destination were 42.9 for basic mobility and 39.4 for daily activity. For basic mobility, the PPV was 0.748 and the NPV was 0.801 in both development and validation samples. For daily activity, the PPVs were 0.787 and 0.784 and the NPVs were 0.748 and 0.746 in development and validation samples, respectively. LIMITATIONS: Limitations included lack of information on the rater reliability of "6-Clicks" instruments, use of surrogate data for some discharge designations, and use of a clinical database for research purposes. CONCLUSIONS: This study provides evidence of the accuracy of "6-Clicks" scores for predicting destination after discharge from an acute care hospital.

Use of a powered coverlet for moisture removal, skin temperature reduction, odor, and bacteria control.

PURPOSE: The purpose of this study was to assess the ability of a powered coverlet (PCL) to control moisture, reduce skin temperature, and help control odor and microbial growth at the skin/support-surface interface. SUBJECTS AND SETTING: A human torso was simulated using a water temperature-regulated loading gauge. The PCL is a 3-tier coverlet composed of vapor-permeable, liquid-impermeable layers with a foam spacer inbetween and a fan blower to draw moisture and heat away from the patient's skin through the spacer. METHODS: A fabric moisture reservoir simulated sweating skin. It was placed between the simulated human torso and pressure redistribution support surface. A change in moisture reservoir weight was used to calculate moisture vapor transfer rate; temperature and relative humidity at the support surface interface were recorded as a function of time. To test for odor control, a malodorous compound was applied daily to the coverlet with and without power for 30 days in a laboratory setting. In a separate test, both a PCL and a standard hospital sheet were inoculated with Staphylococcus aureus and incubated at 32°C to observe the PCL's ability to mitigate microbial growth. RESULTS: Results indicated a higher moisture vapor transfer rate with the PCL as compared to a standard hospital bed sheet (129.5 g/m/h vs 34.1 g/m/h, P < .005). The PCL also had a larger reduction in skin temperature (1.1ºC vs 0.7ºC, P = .13) when compared to control. Gas chromatography analysis showed that the PCL helped control odor better than a non-PCL (P < .05). At 24 hours, the PCL showed greater than 2 log difference of S aureus over the standard hospital sheet (P < .05). CONCLUSIONS: These studies indicate the potential ability of the PCL to remove moisture at the patient/support-surface interface, thus creating a microenvironment with improved moisture management and reduction in odor and microbial growth.

Validity of the AM-PAC "6-Clicks" inpatient daily activity and basic mobility short forms.

BACKGROUND: Standardized assessment of patients' activity limitations in acute care settings can provide valuable information. Existing measures have not been widely implemented. OBJECTIVES: The aim of this study was to provide evidence for validity of scores on Activity Measure for Post-Acute Care (AM-PAC) "6-Clicks" measures of basic mobility and daily activity in acute care. DESIGN: A retrospective measurement study was conducted. METHODS: The study used a database from one health system containing "6-Clicks" scores from first and last physical therapist and occupational therapist visits for 84,446 patients. Validity was analyzed by examining differences in "6-Clicks" scores across categories of patient characteristics; the ability of "6-Clicks" scores to predict patients' having more than one therapy visit; correlation of "6-Clicks" scores with Functional Independence Measure (FIM) scores; and internal responsiveness over the episode of care. Internal consistency reliability also was determined. RESULTS: The "6-Clicks" scores differed across patients' age, preadmission living situation, and number of therapy visits. The areas under receiver operating characteristic curves derived using "6-Clicks" scores at the first visit to predict patients receiving more than one visit were 0.703 and 0.652 using basic mobility and daily activity scores, respectively. The "6-Clicks" scores at the final visit were correlated with scores on subscales of the FIM completed on admission to inpatient rehabilitation facilities (r=.65 and .69). Standardized response means were 1.06 and 0.95 and minimal detectable changes with 90% confidence level (MDC90) were 4.72 and 5.49 for basic mobility and daily activity scores, respectively. Internal consistency reliability of basic mobility and daily activity scores was .96 and .91, respectively. LIMITATIONS: Using clinical databases for research purposes has limitations, including missing data, misclassifications, and selection bias. Rater reliability is not known. CONCLUSIONS: This study provides evidence for the validity of "6-Clicks" scores for assessing patients' activity limitations in acute care settings.

Kinesthetic imagery training of forceful muscle contractions increases brain signal and muscle strength.

The purpose of this study was to compare the effect of training using internal imagery (IMI; also known as kinesthetic imagery or first person imagery) with that of external imagery (EMI; also known as third-person visual imagery) of strong muscle contractions on voluntary muscle strengthening. Eighteen young, healthy subjects were randomly assigned to one of three groups (6 in each group): internal motor imagery (IMI), external motor imagery (EMI), or a no-practice control (CTRL) group. Training lasted for 6 weeks (~15 min/day, 5 days/week). The participants' right arm elbow-flexion strength, muscle electrical activity, and movement-related cortical potential (MRCP) were evaluated before and after training. Only the IMI group showed significant strength gained (10.8%) while the EMI (4.8%) and CTRL (-3.3%) groups did not. Only the IMI group showed a significant elevation in MRCP on scalp locations over both the primary motor (M1) and supplementary motor cortices (EMI group over M1 only) and this increase was significantly greater than that of EMI and CTRL groups. These results suggest that training by IMI of forceful muscle contractions was effective in improving voluntary muscle strength without physical exercise. We suggest that the IMI training likely strengthened brain-to-muscle (BTM) command that may have improved motor unit recruitment and activation, and led to greater muscle output. Training by IMI of forceful muscle contractions may change the activity level of cortical motor control network, which may translate into greater descending command to the target muscle and increase its strength.

Myoelectrical manifestation of fatigue less prominent in patients with cancer related fatigue.

PURPOSE: A lack of fatigue-related muscle contractile property changes at time of perceived physical exhaustion and greater central than peripheral fatigue detected by twitch interpolation technique have recently been reported in cancer survivors with fatigue symptoms. Based on these observations, it was hypothesized that compared to healthy people, myoelectrical manifestation of fatigue in the performing muscles would be less significant in these individuals while sustaining a prolonged motor task to self-perceived exhaustion (SPE) since their central fatigue was more prominent. The purpose of this study was to test this hypothesis by examining electromyographic (EMG) signal changes during fatiguing muscle performance. METHODS: Twelve individuals who had advanced solid cancer and cancer-related fatigue (CRF), and 12 age- and gender-matched healthy controls performed a sustained elbow flexion at 30% maximal voluntary contraction till SPE. Amplitude and mean power frequency (MPF) of EMG signals of the biceps brachii, brachioradialis, and triceps brachii muscles were evaluated when the individuals experienced minimal, moderate, and severe fatigue. RESULTS: CRF patients perceived physical "exhaustion" significantly sooner than the controls. The myoelectrical manifestation of muscular fatigue assessed by EMG amplitude and MPF was less significant in CRF than controls. The lower MPF even at minimal fatigue stage in CRF may indicate pathophysiologic condition of the muscle. CONCLUSIONS: CRF patients experience less myoelectrical manifestation of muscle fatigue than healthy individuals near the time of SPE. The data suggest that central nervous system fatigue plays a more important role in limiting endurance-type of motor performance in patients with CRF.

United States registered nurse workforce report card and shortage forecast.

Registered nurses (RNs) play a critical role in health care delivery. With an aging US population, health care demand is growing at an unprecedented pace. Using projected changes in population size and age, the authors developed demand and supply models to forecast the RN job shortage in each of the 50 states. Letter grades were assigned based on projected RN job shortage ratios. The number of states receiving a grade of "D" or "F" for their RN shortage ratio will increase from 5 in 2009 to 30 by 2030, for a total national deficit of 918 232 (725,619 - 1,112,112) RN jobs. There will be significant RN workforce shortages throughout the country in 2030; the western region will have the largest shortage ratio of 389 RN jobs per 100,000. Increased efforts to understand shortage dynamics are warranted.

Cancer-related fatigue: central or peripheral?

To evaluate cancer-related fatigue (CRF) by objective measurements to determine if CRF is a more centrally or peripherally mediated disorder, cancer patients and matched noncancer controls completed a Brief Fatigue Inventory (BFI) and underwent neuromuscular testing. Cancer patients had fatigue measured by the BFI, were off chemotherapy and radiation (for more than four weeks), had a hemoglobin level higher than 10 g/dL, and were neither receiving antidepressants nor were depressed on a screening question. The controls were screened for depression and matched by age, gender, and body mass index. Neuromuscular testing involved a sustained submaximal elbow flexion contraction (SC) at 30% maximal level (30% maximum elbow flexion force). Endurance time (ET) was measured from the beginning of the SC to the time when participants could not maintain the SC. Evoked twitch force (TF), a measure of muscle fatigue, and compound action potential (M-wave), an assessment of neuromuscular-junction transmission were performed during the SC. Compared with controls, the CRF group had a higher BFI score (P<0.001), a shorter ET (P<0.001), and a greater TF with the SC (CRF>controls, P<0.05). This indicated less muscle fatigue. There was a greater TF (P<0.05) at the end of the SC, indicating greater central fatigue, in the CRF group, which failed to recruit muscle (to continue the SC), as well as the controls. M-Wave amplitude was lower in the CRF group than in the controls (P<0.01), indicating impaired neuromuscular junction conduction with CRF unrelated to central fatigue (M-wave amplitude did not change with SC). These data demonstrate that CRF patients exhibited greater central fatigue, indicated by shorter ET and less voluntary muscle recruitment during an SC relative to controls.

Weakening of functional corticomuscular coupling during muscle fatigue.

OBJECTIVE: Recent research has shown dissociation between changes in brain and muscle signals during voluntary muscle fatigue, which may suggest weakening of functional corticomuscular coupling. However, this weakening of brain-muscle coupling has never been directly evaluated. The purpose of this study was to address this issue by quantifying EEG-EMG coherence at times when muscles experienced minimal versus significant fatigue. METHODS: Nine healthy subjects sustained an isometric elbow flexion at 30% maximal level until exhaustion while their brain (EEG) and muscle (EMG) activities were recorded. The entire duration of the EEG and EMG recordings was divided into the first half (stage 1 with minimal fatigue) and second half (stage 2 with severer fatigue). The EEG-EMG coherence and power spectrum in each stage was computed. RESULTS: The power of both EEG and EMG increased significantly while their coherence decreased significantly in stage 2 compared with stage 1 at beta (15-35 Hz) band. CONCLUSIONS: Despite an elevation of the power for both the EEG and EMG activities with muscle fatigue, the fatigue weakens strength of brain-muscle signal coupling at beta frequency band. SIGNIFICANCE: Weakening of corticomuscular coupling may be a major neural mechanism contributing to muscle fatigue and associated performance impairment.

Combining objective and subjective outcomes in cancer-related fatigue: illustrations from a single case report.

Neurophysiologic measurements were made on a patient with multiple lung cancers and severe cancer-related fatigue (CRF) who responded to 5 mg methylphenidate twice daily, titrated to 10 mg twice daily after 2 weeks. She remained at 10 mg twice daily for 8 months. Improvement in severe CRF (Brief Fatigue Inventory score) was associated with normalization of neurophysiologic tests.

Support surface interface pressure, microenvironment, and the prevalence of pressure ulcers: an analysis of the literature.

External pressure is the most frequently considered stress factor in the formation of ulcers. A review and analysis of existing literature addressing the relationship between pressure ulcer prevalence and interface pressures at various anatomic sites was conducted. Results suggest a nearly non-existent or slightly negative correlation between interface pressure and ulcer prevalence in general and spinal cord injured populations, respectively. Despite limitations of the analysis methods used, the observed lack of a direct relationship confirms the results of other studies and suggests that ulcer formation also may involve factors secondary to pressure and mechanical factors (eg, temperature, moisture, duration of the applied load, atrophy, and posture). Based on currently available information, clinicians should include these considerations when selecting a support surface. Studies directly relating primary stress factors and tissue viability with prevalence and incidence of pressure ulcers are needed to better understand the benefits of pressure-relieving support surfaces and to improve the effectiveness of prevention and treatment.

Classification of large array surface myoelectric potentials from subjects with and without low back pain.

An algorithm was developed and tested for differentiating between the spatial distribution of large arrays of surface electromyographic (LASE) data from subjects with and without low back pain (LBP). The surface EMG data from 62 channels were collected from the low back of 161 healthy and 44 acute (less than 6-weeks) LBP subjects in three minimum stress postural positions including standing, 20 degrees of trunk flexion (at hip joint) and standing with arms extended forward holding a 1.36kg (3lb) weight in each hand. These data were statistically analyzed and the spatial distribution of the root mean square (RMS) values was used in a multivariate quadratic discriminant model to reclassify the healthy and acute LBP subjects. The most predictive results were obtained from the 'flexion' group of experiments and correctly reclassified 95.5% (42/44) of the acute LBP subjects and 99.4% (160/161) of the healthy subjects. The success rate of this reclassification based on surface distribution of myoelectric potentials was found to be better than the reported patient classifications based on a smaller set of electrode pairs using fewer subjects [Peach JP, McGill SM, Classification of low back pain with use of spectral electromyogram parameters. Spine 23(10):1998;1117-23; Roy SH, De Luca CJ, Emley M, Oddsson LI, Buijs RJ, Levins JA, Newcombe DS, Jabre JF. Classification of back muscle impairment based on the surface electromyographic signal. J Rehabil Res Dev 34(4):1997;405-14 [review]]. The results indicated the potential of the model for clinical patient classification.