Model-based assessment and mapping of total phosphorus enrichment in rivers with sparse reference data

Water nutrient management efforts are frequently coordinated across thousands of water bodies, leading to a need for spatially extensive information to facilitate decision making. Here we explore potential applications of a machine learning model of river low-flow total phosphorus (TP) concentrations to support landscape nutrient management. The model was trained, validated, and then applied for all rivers of Michigan, USA to identify potential drivers of nutrient variation, predict alteration in nutrient concentrations from minimally disturbed conditions, and explore reach specific sensitivity to riparian agricultural change. A boosted regression tree model of low-flow TP concentrations trained on natural and anthropogenic landscape predictors accounted for 53 % of variation in cross-validation data, had good accuracy, little bias, and plausible relationships between predictors and response. Percent riparian agricultural cover accounted for the greatest root mean square error reduction in the modeled response (33.2 %), followed by riparian soil permeability (12.9 %), watershed slope (9.6 %), and percent urban cover (9.6 %). An apparent non-linear relationship between TP concentrations and percent riparian agricultural cover suggested steep positive increases in stream TP concentrations between 10 and 30 % upstream riparian agricultural cover. Predicted minimally disturbed TP concentrations were spatially variable and ranged from 7.0 to 48.5 μg l^-1, with the highest concentrations in watersheds draining low-permeability lake plain soils. Comparison of minimally disturbed predictions to those from the early 2000s suggested that much of northern Michigan existed close to the reference condition, while lower Michigan streams were often substantially enriched. Our predicted values of minimally disturbed condition generally agree with previous studies but offer greater geographic specificity. Expanded application of machine learning modeling with landscape predictor data have great potential to inform large scale strategy development in landscapes with sparse reference data.

Contracture Severity at Hospital Discharge in Children: A Burn Model System Database Study

Contractures can complicate burn recovery. There are limited studies examining the prevalence of contractures following burns in pediatrics. This study investigates contracture outcomes by location, injury, severity, length of stay, and developmental stage. Data were obtained from the Burn Model System between 1994 and 2003. All patients younger than the age of 18 with at least one joint contracture at hospital discharge were included. Sixteen areas of impaired movement from the shoulder, elbow, wrist, hand, hip, knee, and ankle joints were examined. Analysis of variance was used to assess the association between contracture severity, burn size, and length of stay. Age groupings were evaluated for developmental patterns. A P value of less than .05 was considered statistically significant. Data from 225 patients yielded 1597 contractures (758 in the hand) with a mean of 7.1 contractures (median 4) per patient. Mean contracture severity ranged from 17% (elbow extension) to 41% (ankle plantarflexion) loss of movement. Statistically significant associations were found between active range of motion loss and burn size, length of stay, and age groupings. The data illustrate quantitative assessment of burn contractures in pediatric patients at discharge in a multicenter database. Size of injury correlates with range of motion loss for many joint motions, reflecting the anticipated morbidity of contracture for pediatric burn survivors. These results serve as a potential reference for range of motion outcomes in the pediatric burn population, which could serve as a comparison for local practices, quality improvement measures, and future research.

Outsized nutrient contributions from small tributaries to a Great Lake

Excessive nitrogen (N) and phosphorus (P) loading is one of the greatest threats to aquatic ecosystems in the Anthropocene, causing eutrophication of rivers, lakes, and marine coastlines worldwide. For lakes across the United States, eutrophication is driven largely by nonpoint nutrient sources from tributaries that drain surrounding watersheds. Decades of monitoring and regulatory efforts have paid little attention to small tributaries of large water bodies, despite their ubiquity and potential local importance. We used a snapshot of nutrient inputs from nearly all tributaries of Lake Michigan-the world's fifth largest freshwater lake by volume-to determine how land cover and dams alter nutrient inputs across watershed sizes. Loads, concentrations, stoichiometry (N:P), and bioavailability (percentage dissolved inorganic nutrients) varied by orders of magnitude among tributaries, creating a mosaic of coastal nutrient inputs. The 6 largest of 235 tributaries accounted for ∼70% of the daily N and P delivered to Lake Michigan. However, small tributaries exhibited nutrient loads that were high for their size and biased toward dissolved inorganic forms. Higher bioavailability of nutrients from small watersheds suggests greater potential to fuel algal blooms in coastal areas, especially given the likelihood that their plumes become trapped and then overlap in the nearshore zone. Our findings reveal an underappreciated role that small streams may play in driving coastal eutrophication in large water bodies. Although they represent only a modest proportion of lake-wide loads, expanding nutrient management efforts to address smaller watersheds could reduce the ecological impacts of nutrient loading on valuable nearshore ecosystems.

A Comparison of Contracture Severity at Acute Discharge in Patients With and Without Heterotopic Ossification: A Burn Model System National Database Study

This study assesses the association between heterotopic ossification and upper extremity contracture by comparing goniometric measured active range of motion outcomes of patients with and without heterotopic ossification. Data were obtained from the Burn Model System National Database between 1994 and 2003 for patients more than 18 years with elbow contracture at acute discharge. Absolute losses in elbow range of motion were compared for those with and without radiologic evidence of heterotopic ossification (location undefined) and were further examined by burn size subgroups using Wilcoxon rank-sum test. Differences in elbow range of motion were estimated using regression models, adjusted for demographic and clinical variables. Loss of range of motion of shoulder, wrist, forearm, and hand were also compared. From 407 instances of elbow contracture, the subjects with heterotopic ossification were found to have greater median absolute loss of elbow flexion among all survivors (median 50° [IQR 45°] vs 20° [30°], P < .0001), for the 20 to 40% total body surface area burn subgroup (70° [20°] vs 20° [30°], P = .0008) and for the >40% subgroup (50° [45°] vs 30° [32°], P = .03). The adjusted estimate of the mean difference in the absolute loss of elbow flexion between groups was 23.5° (SE ±7.2°, P = .0013). This study adds to our understanding of the potential effect of heterotopic ossification on upper extremity joint range of motion, demonstrating a significant association between the presence of heterotopic ossification and elbow flexion contracture severity. Further study is needed to determine the functional implications of heterotopic ossification and develop treatment protocols.

The impact of discharge contracture on return to work after burn injury: A Burn Model System investigation

INTRODUCTION

Despite many advances in burn care, the development of extremity contracture remains a common and vexing problem. Extremity contractures have been documented in up to one third of severely burned patients at discharge. However, little is known about the long-term impact of these contractures. The purpose of this study was to examine the association of extremity contractures with employment after burn injury.

METHODS

We obtained data from the Burn Model System database from 1994 to 2003. We included in the study cohort all adult patients who were working prior to injury and identified those discharged with and without a contracture in one of the major extremity joints (shoulder, elbow, wrist, hip, knee and ankle). We classified contracture severity according to mild, moderate and severe categories. We performed descriptive analyses and predictive modeling to identify injury and patient factors associated with return to work (RTW) at 6, 12, and 24 months.

RESULTS

A total of 1,203 participant records met criteria for study inclusion. Of these, 415 (35%) had developed a contracture at discharge; 9% mild, 12% moderate, and 14% severe. Among 801 (67%) participants who had complete data at 6 months after discharge, 70% of patients without contracture had returned to work compared to 45% of patients with contractures (p < 0.001). RTW increased at each subsequent follow-up time point for the contracture group, however, it remained significantly lower than in no-contracture group (both p < 0.01). In multivariable analyses, female sex, non-Caucasian ethnicity, larger burn size, alcohol abuse, number of in-hospital operations, amputation, and in-hospital complications were associated with a lower likelihood of employment. In adjusted analyses, discharge contracture was associated with a lower probability of RTW at all 3 time points, although its impact significantly diminished at 24 months.

CONCLUSIONS

This study indicates an association between discharge contracture and reduced employment 6, 12 and 24 months after burn injury. Among many other identified patient, injury, and hospitalization related factors that are barriers to RTW, the presence of a contracture at discharge adds a significant reintegration burden for working-age burn patients.

Quantifying Contracture Severity at Hospital Discharge in Adults: A Burn Model System National Database Study

Contracture is a common complication of burn injury and can cause significant barriers to functional recovery and rehabilitation. There are limited studies of quantitative range of motion after burn injury. The purpose of this study is to examine quantitative contracture outcomes by anatomical location, burn size, and length of stay in adults. Data were obtained from the Burn Model System National Database from 1994 to 2003. All adult patients with a joint contracture at acute discharge were included and 16 joint motions were examined. Contractures were reported as both mean absolute loss of normal range of motion in degrees and percent loss of normal range of motion. Analysis of variance was used to assess for a linear trend for contracture severity by burn size and length of stay. Data from 659 patients yielded 6,228 instances of contracture. Mean absolute loss of normal range of motion ranged from 20° to 65° representing an 18 to 45% loss of normal movement across the studied joint motions. In the majority of joint motions, contracture severity significantly increased with larger burn size and longer length of stay; however, wrist and many lower extremity joint movements did not demonstrate this trend. The data illustrate the quantitative assessment of range of motion deficits in adults with burn injury at discharge and the relation to burn size and length of stay.

Elevated energy coupling and aerobic capacity improves exercise performance in endurance-trained elderly subjects

Increased maximal oxygen uptake (V(O(2)max)), mitochondrial capacity and energy coupling efficiency are reported after endurance training (ET) in adult subjects. Here we test whether leg exercise performance (power output of the legs, P(max), at V(O(2)max)) reflects these improvements with ET in the elderly. Fifteen male and female subjects were endurance trained for a 6 month programme, with 13 subjects (69.5 ± 1.2 years old, range 65-80 years old; n = 7 males; n = 6 females) completing the study. This training significantly improved P(max) (Δ17%; P = 0.003), V(O(2)max) (Δ5.4%; P = 0.021) and the increment in oxygen uptake (V(O(2))) above resting (ΔV(O(2)m-r) = V(O(2)max) - V(O(2)rest; Δ9%; P < 0.02). In addition, evidence of improved energy coupling came from elevated leg power output per unit V(O(2))at the aerobic capacity [Δ(P(max)/ΔV(O(2)m-r)); P = 0.02] and during submaximal exercise in the ramp test as measured by delta efficiency (ΔP(ex)/ΔV(O(2)); P = 0.04). No change was found in blood lactate, muscle glycolysis or fibre type. The rise in P(max) paralleled the improvement in muscle oxidative phosphorylation capacity (ATP(max)) in these subjects. In addition, the greater exercise energy coupling [Δ(P(max)/ΔV(O(2)m-r)) and delta efficiency] was accompanied by increased mitochondrial energy coupling as measured by elevated ATP production per unit mitochondrial content in these subjects. These results suggest that leg exercise performance benefits from elevations in energy coupling and oxidative phosphorylation capacity at both the whole-body and muscle levels that accompany endurance training in the elderly.

Harborview burns--1974 to 2009

BACKGROUND

Burn demographics, prevention and care have changed considerably since the 1970s. The objectives were to 1) identify new and confirm previously described changes, 2) make comparisons to the American Burn Association National Burn Repository, 3) determine when the administration of fluids in excess of the Baxter formula began and to identify potential causes, and 4) model mortality over time, during a 36-year period (1974-2009) at the Harborview Burn Center in Seattle, WA, USA.

METHODS AND FINDINGS

14,266 consecutive admissions were analyzed in five-year periods and many parameters compared to the National Burn Repository. Fluid resuscitation was compared in five-year periods from 1974 to 2009. Mortality was modeled with the rBaux model. Many changes are highlighted at the end of the manuscript including 1) the large increase in numbers of total and short-stay admissions, 2) the decline in numbers of large burn injuries, 3) that unadjusted case fatality declined to the mid-1980s but has changed little during the past two decades, 4) that race/ethnicity and payer status disparity exists, and 5) that the trajectory to death changed with fewer deaths occurring after seven days post-injury. Administration of fluids in excess of the Baxter formula during resuscitation of uncomplicated injuries was evident at least by the early 1990s and has continued to the present; the cause is likely multifactorial but pre-hospital fluids, prophylactic tracheal intubation and opioids may be involved.

CONCLUSIONS

1) The dramatic changes include the rise in short-stay admissions; as a result, the model of burn care practiced since the 1970s is still required but is no longer sufficient. 2) Fluid administration in excess of the Baxter formula with uncomplicated injuries began at least two decades ago. 3) Unadjusted case fatality declined to ∼6% in the mid-1980s and changed little since then. The rBaux mortality model is quite accurate.

Preinjury alcohol and drug use among persons with spinal cord injury: implications for rehabilitation

CONTEXT/OBJECTIVE

To describe preinjury alcohol and drug use and opportunities for secondary prevention among persons with recent spinal cord injury (SCI).

DESIGN

Survey.

SETTING

Acute inpatient rehabilitation program.

PARTICIPANTS

Participants were 118 (84.8%) of 139 consecutive admissions who met inclusion criteria and were screened for preinjury alcohol and drug use.

INTERVENTIONS

None.

OUTCOME MEASURES

Alcohol and drug use, toxicology results, alcohol problems, readiness to change, and treatment preferences.

RESULTS

Participants were on average 37 years old, 84% were men, and 85% were white. Fifty-one percent of the sample was considered 'at-risk' drinkers. Significant lifetime alcohol-related problems were reported by 38% of the total sample. Thirty-three percent reported recent illicit drug use and 44% of the 82 cases with toxicology results were positive for illicit drugs. Seventy-one percent of at-risk drinkers reported either considering changes in alcohol use or already taking action. Forty-one percent reported interest in trying substance abuse treatment or Alcoholics Anonymous (AA). Motivation to change alcohol use was significantly and positively associated with self-reported indicators of alcohol problem severity.

CONCLUSION

Preinjury alcohol and drug abuse are common among persons with recent SCI. Substance abuse screening is feasible and detects not only salient clinical problems but also significant motivation to change and interest in AA or treatment, all of which represent an important window of opportunity for appropriate brief interventions and referrals. In contrast with the idea that alcoholism is a 'disease of denial', the majority of at-risk drinkers with new onset SCI indicate they are considering making changes.

Rates of major depressive disorder and clinical outcomes following traumatic brain injury

CONTEXT

Uncertainties exist about the rates, predictors, and outcomes of major depressive disorder (MDD) among individuals with traumatic brain injury (TBI).

OBJECTIVE

To describe MDD-related rates, predictors, outcomes, and treatment during the first year after TBI.

DESIGN

Cohort from June 2001 through March 2005 followed up by structured telephone interviews at months 1 through 6, 8, 10, and 12 (data collection ending February 2006).

SETTING

Harborview Medical Center, a level I trauma center in Seattle, Washington.

PARTICIPANTS

Five hundred fifty-nine consecutively hospitalized adults with complicated mild to severe TBI.

MAIN OUTCOME MEASURES

The Patient Health Questionnaire (PHQ) depression and anxiety modules were administered at each assessment and the European Quality of Life measure was given at 12 months.

RESULTS

Two hundred ninety-seven of 559 patients (53.1%) met criteria for MDD at least once in the follow-up period. Point prevalences ranged between 31% at 1 month and 21% at 6 months. In a multivariate model, risk of MDD after TBI was associated with MDD at the time of injury (risk ratio [RR], 1.62; 95% confidence interval [CI], 1.37-1.91), history of MDD prior to injury (but not at the time of injury) (RR, 1.54; 95% CI, 1.31-1.82), age (RR, 0.61; 95% CI, 0.44-0.83 for > or = 60 years vs 18-29 years), and lifetime alcohol dependence (RR, 1.34; 95% CI, 1.14-1.57). Those with MDD were more likely to report comorbid anxiety disorders after TBI than those without MDD (60% vs 7%; RR, 8.77; 95% CI, 5.56-13.83). Only 44% of those with MDD received antidepressants or counseling. After adjusting for predictors of MDD, persons with MDD reported lower quality of life at 1 year compared with the nondepressed group.

CONCLUSIONS

Among a cohort of patients hospitalized for TBI, 53.1% met criteria for MDD during the first year after TBI. Major depressive disorder was associated with history of MDD and was an independent predictor of poorer health-related quality of life.

The effect of telephone counselling on reducing post-traumatic symptoms after mild traumatic brain injury: a randomised trial

BACKGROUND

Mild traumatic brain injury (MTBI) is a significant public health problem affecting approximately 1 million people annually in the USA. A total of 10-15% of individuals are estimated to have persistent post-traumatic symptoms. This study aimed to determine whether focused, scheduled telephone counselling during the first 3 months after MTBI decreases symptoms and improves functioning at 6 months.

METHODS

This was a two-group, parallel, randomised clinical trial with the outcome assessed by blinded examiner at 6 months after injury. 366 of 389 eligible subjects aged 16 years or older with MTBI were enrolled in the emergency department, with an 85% follow-up completion rate. Five telephone calls were completed, individualised for patient concerns and scripted to address education, reassurance and reactivation. Two composites were analysed, one relating to post-traumatic symptoms that developed or worsened after injury and their impact on functioning, the other related to general health status.

RESULTS

The telephone counselling group had a significantly better outcome for symptoms (6.6 difference in adjusted mean symptom score, 95% confidence interval (CI) 1.2 to 12.0), but no difference in general health outcome (1.5 difference in adjusted mean functional score, 95% CI 2.2 to 5.2). A smaller proportion of the treatment group had each individual symptom (except anxiety) at assessment. Similarly, fewer of the treatment group had daily functioning negatively impacted by symptoms with the largest differences in work, leisure activities, memory and concentration and financial independence.

CONCLUSIONS

Telephone counselling, focusing on symptom management, was successful in reducing chronic symptoms after MTBI.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, #NCT00483444.

The WeeFIM [R] instrument--a paediatric measure of functional independence to predict longitudinal recovery of paediatric burn patients

INTRODUCTION

Burns create a myriad of complications that affect the child's developmental, functional and aesthetic status. The WeeFIM is a standardized measure of functional performance developed for use in children 6-months to 8-years of age but with application through adolescence. It includes 18 domains of performance which are scored on a 7-point scale from 'total assistance' to 'complete independence'. In this study, the WeeFIM was used to evaluate the influence of burn size on functional independence and on time to recovery.

METHODS

Children, 6 months to 16 years of age, with total body surface area (TBSA) bums of 10-100% burn injury were recruited for a 2-year longitudinal study. Due to unstable WeeFIM measurements on children 6 months to 6 years, analyses on normalized WeeFIM scores among subjects 6-16 years are presented. Children were evaluated at discharge from acute care, 6 months, 1 year and 2 years after burn injury.

FINDINGS

In this analysis, 454 WeeFIM evaluations from 249 patients, 6-16 years of age, were reviewed. While mean WeeFIM scores varied significantly at discharge based on the size of burn, there were no significant differences in any of the WeeFIM scales at 24 months post-burn. At 24 months, the mean WeeFIM score for all children, independent of size of their bum, indicated full independence. Hands-on assistance was not required for performing activities of daily living (ADLs). The rates of improvement differed statistically by size of bum. Maximum improvement was attained by 6 months for 10-15% TBSA burns, 12 months for 16-30% burns, 12 months for 31-50% burns and 24 months for 51-100% TBSA.

CONCLUSION

The WeeFIM can be utilized by burn centres to describe diminished functional capacity at discharge from acute care for severely burnt children. The tool can be used to track return to baseline independence after a major burn injury in a paediatric population.

Burn rehabilitation: an overview

Burn injuries result in significant physical and psychologic complications that require comprehensive rehabilitation treatment and coordination with the acute care burn team. This interdisciplinary rehabilitation treatment is focused on preventing long-term problems with scarring, contractures, and other problems that limit physical function. Adequate pain management and recognition of psychologic issues are important components of treatment after burn injuries. Burn injuries present significant barriers to community integration, but many people can successfully return to work and other activities.

Posttraumatic stress disorder symptoms during the first six months after traumatic brain injury

Controversy exists regarding the rate and risk factors for posttraumatic stress disorder (PTSD) following traumatic brain injury (TBI). The authors determined the rate and phenomenology of PTSD symptoms in the 6 months after TBI by conducting a prospective cohort study of 124 subjects who completed the PTSD Checklist-Civilian Version. The cumulative incidence of meeting PTSD symptom criteria at 6 months was 11% and full criteria 5.6%. Prevalence peaked at 1 month (10%). Eighty-six percent had another psychiatric disorder and 29% a history of PTSD. Symptoms were associated with not completing high school, assault, recalling being terrified or helpless, and positive toxicology. PTSD after TBI is rare and the relation to risk factors and comorbidities must be examined.

The National Institute on Disability and Rehabilitation Research Burn Model System Database: A Tool for the Multicenter Study of the Outcome of Burn Injury

Advances in critical care and surgical management have significantly improved survival after burn injury over the past several decades. However, today, survival alone is an insufficient outcome. In 1994, the National Institute on Disability and Rehabilitation Research (NIDRR) created a burn model system program to evaluate the long-term sequelae of burn injuries. As part of this multicenter program, a comprehensive demographic and outcome database was developed to facilitate the study of a number of functional and psychosocial outcomes after burns. The purpose of this study is to review the database design and structure as well as the data obtained during the last 10 years. This is a descriptive study of the NIDRR database structure as well as the patient data obtained from the four participating burn centers from 1994 to 2004. Data obtained during hospitalization and at 6, 12, and 24 months after discharge were reviewed and descriptive statistics were calculated for select database fields. The database is divided into several subsections, including demographics, injury complications, patient disposition, and functional and psychological surveys. A total of 4600 patients have been entered into the NIDRR database. To date, 3449 (75%) patients were alive at discharged and consented to follow-up data collection. The NIDRR database provides an expansive repository of patient, injury, and outcome data that can be used to analyze the impact of burn injury on physical and psychosocial function and for the design of interventions to enhance the quality of life of burn survivors.

The Effect of a Scheduled Telephone Intervention on Outcome After Moderate to Severe Traumatic Brain Injury: A Randomized Trial

OBJECTIVE

To measure the effectiveness of a scheduled telephone intervention offering counseling and education to people with traumatic brain injury (TBI) on behavioral outcomes compared with standard follow-up at 1 year postinjury.

DESIGN

Two-group randomized, prospective clinical trial throughout the first year after injury.

SETTING

Subjects' homes via telephone in an urban-rural catchment area from a level I trauma center.

PARTICIPANTS

Subjects (N=171; age range, 18-70 y) with a primary diagnosis of TBI who were discharged from an acute rehabilitation unit. They were randomly assigned to the telephone intervention (n=85) or to standard follow-up (n=86) groups at discharge. Of these, 79 participated in the intervention and completed the outcome assessment (3 withdrew; 3 were lost to follow-up), and 78 participated in usual care and completed the outcome assessment (8 were lost to follow-up).

INTERVENTIONS

Subjects were randomly assigned to receive telephone calls at 2 and 4 weeks and 2, 3, 5, 7, and 9 months after discharge. The calls consisted of brief motivational interviewing, counseling, and education, plus facilitating usual care or usual care alone through follow-up appointments and therapy prescriptions.

MAIN OUTCOME MEASURES

A composite outcome was used as the primary endpoint on an intent-to-treat basis. Secondary analyses were conducted with individual measures, including the FIM instrument, Disability Rating Scale, Community Integration Questionnaire, Neurobehavioral Functioning Inventory, Functional Status Examination, Glasgow Outcome Scale-Extended, Medical Outcomes Study 36-Item Short-Form Health Survey, Brief Symptom Inventory, EuroQol, and Modified Perceived Quality of Life scale. The primary analysis was a blocked Mann-Whitney U test.

RESULTS

At 1-year follow-up, those who had received scheduled telephone intervention fared significantly better on the primary composite outcome index ( P =.002). In addition, this group fared better on specific composites such as functional status ( P =.003) and quality of well-being ( P =.006). There were no significant differences on vocational status ( P =.08) or community integration status ( P =.13).

CONCLUSIONS

Scheduled telephone counseling and education resulted in improved overall outcome, particularly for functional status and quality of well-being, when compared with usual outpatient care. Telephone counseling shows promise as a low-cost, widely available rehabilitation intervention for TBI.

Do preinjury alcohol problems predict poorer rehabilitation progress in persons with spinal cord injury?

OBJECTIVE

To determine whether a history of alcohol-related problems is associated with inpatient rehabilitation progress.

DESIGN

Cross-sectional cohort survey.

SETTING

Acute inpatient rehabilitation program in a level I trauma center.

PARTICIPANTS

Seventy-six of 104 consecutive patients with spinal cord injury (SCI) who met inclusion criteria and had completed interviews and functional outcome data. Participants were on average 38 years old; 84% were white, and 86% were men. Forty-two percent had tetraplegia and 39% had a history of problem drinking.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

FIM instrument admission, discharge, and efficiency scores as well as rehabilitation length of stay (LOS).

RESULTS

The group with a history of problem drinking had significantly lower FIM admission, discharge, and efficiency scores and longer rehabilitation LOS. After controlling for potential confounding factors, a history of problem drinking accounted for a significant proportion of the variance in FIM efficiency scores.

CONCLUSIONS

A history of problem drinking may be a risk factor for poorer rehabilitation progress among patients with SCI. They may be more costly to rehabilitate and may be discharged before attaining an adequate level of independence. Despite this, the current rehabilitation prospective payment system does not recognize this common comorbid condition.

Access to inpatient rehabilitation after violence-related traumatic brain injury11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the author(s) or on any organization with which the author(s) is/are associated

OBJECTIVES

To examine injury characteristics, demographics, and discharge disposition after traumatic brain injury of violent or nonviolent cause.

DESIGN

Cohort study.

SETTING

Level I trauma center.

PARTICIPANTS

Patients (N=1807) admitted with a Head Abbreviated Injury Score (AIS) of 2 or more over a 2-year period.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Injury cause was classified as violent or nonviolent. Discharge disposition was classified as home, inpatient rehabilitation, skilled nursing facility (SNF), and other.

RESULTS

The violence group was more likely to be male, to include individuals from diverse racial groups, to have an alcohol level above the legal limit, to have a more severe Head AIS, and to have Medicaid funding and equal access to inpatient rehabilitation compared with the nonviolence group. The violence group, though, was more likely to be discharged to home than to inpatient rehabilitation and more likely to be discharged to inpatient rehabilitation than to an SNF. The nonviolence group had a longer acute care length of stay and a higher rate of injuries to other body systems.

CONCLUSIONS

People with violence-related injuries often present unique rehabilitation challenges. After accounting for injury severity and demographics, there was no evidence of bias against the violently injured in gaining access to inpatient rehabilitation services.

Impairment after burns: a two-center, prospective report

Impairment rating is regularly reported for trauma and other conditions but rarely for burns. The purposes of this study were: (1) to report impairment collected prospectively at our burn center, (2) to relate this impairment to measures of psychosocial and functional outcome, and (3) to compare these data to similar data from another burn center to verify that rating impairment is standardized and that the impairments are similar. We studied 139 patients from the University of Washington (UW) Burn Center and 100 patients from the University of Texas (UT) Southwestern Burn Center. The average whole person impairment (WPI) ratings at the University of Washington were 17% and this correlated with total body surface area burned and days off work. It did not correlate with Brief Symptom Inventory (BSI), Functional Independence Measure (FIM), Short-Form 36-Item Health Survey (SF-36), Satisfaction With Life Scale (SWLS), and the Community Integration Questionnaire (CIQ). Average whole person impairment ratings at UT Southwestern were similar at 19%. Several components of the impairment rating, however, differed at the two institutions. To minimize this variation, we recommend: (1) use the skin impairment definitions of the fifth edition of the Guides to the Evaluation of Permanent Impairment (or the most recent published versions of the Guide), and (2) include sensory impairment in healed burns and skin grafts in the skin impairment.

Morbidity and management conference: an approach to quality improvement in brain injury rehabilitation

BACKGROUND

Program Evaluation and Quality Improvement (QI) are an ongoing focus of all brain injury rehabilitation programs, but it is difficult to consistently include the entire rehabilitation team in QI activities and to focus on issues that cross the continuum of care. In addition, recent reports have provided a renewed emphasis on reduction of medical errors and improving the overall quality of care for individuals with chronic conditions. Rehabilitation Medicine has a long history of working as a coordinated multidisciplinary team caring for complex patients with chronic conditions and is in a position to be a leader in QI activities.

DESIGN

We have modified the traditional Morbidity and Mortality conference to include a multidisciplinary case discussion to identify system issues with quality of care.

SETTING

This is completed in a nonpunitive format that does not assign individual blame.

CONCLUSION

This Rehabilitation Morbidity and Management Conference is an important addition to the QI activities of our program.

Time off work and return to work rates after burns: systematic review of the literature and a large two-center series

The literature on time off work and return to work after burns is incomplete. This study addresses this and includes a systematic literature review and two-center series. The literature was searched from 1966 through October 2000. Two-center data were collected on 363 adults employed outside of the home at injury. Data on employment, general demographics, and burn demographics were collected. The literature search found only 10 manuscripts with objective data, with a mean time off work of 10 weeks and %TBSA as the most important predictor of time off work. The mean time off work for those who returned to work by 24 months was 17 weeks and correlated with %TBSA. The probability of returning to work was reduced by a psychiatric history and extremity burns and was inversely related to %TBSA. In the two-center study, 66% and 90% of survivors had returned to work at 6 and 24 months post-burn. However, in the University of Washington subset of the data, only 37% had returned to the same job with the same employer without accommodations at 24 months, indicating that job disruption is considerable. The impact of burns on work is significant.

Large energetic adaptations of elderly muscle to resistance and endurance training

This study determined the cellular energetic and structural adaptations of elderly muscle to exercise training. Forty male and female subjects (69.2 +/- 0.6 yr) were assigned to a control group or 6 mo of endurance (ET) or resistance training (RT). We used magnetic resonance spectroscopy and imaging to characterize energetic properties and size of the quadriceps femoris muscle. The phosphocreatine and pH changes during exercise yielded the muscle oxidative properties, glycolytic ATP synthesis, and contractile ATP demand. Muscle biopsies taken from the same site as the magnetic resonance measurements were used to determine myosin heavy chain isoforms, metabolite concentrations, and mitochondrial volume densities. The ET group showed changes in all energetic pathways: oxidative capacity (+31%), contractile ATP demand (-21%), and glycolytic ATP supply (-56%). The RT group had a large increase in oxidative capacity (57%). Only the RT group exhibited change in structural properties: a rise in mitochondrial volume density (31%) and muscle size (10%). These results demonstrate large energetic, but smaller structural, adaptations by elderly muscle with exercise training. The rise in oxidative properties with both ET and RT suggests that the aerobic pathway is particularly sensitive to exercise training in elderly muscle. Thus elderly muscle remains adaptable to chronic exercise, with large energetic changes accompanying both ET and RT.

Community integration after burn injuries

Evaluation of community integration is a meaningful outcome criterion after major burn injury. The Community Integration Questionnaire (CIQ) was administered to 463 individuals with major burn injuries. The CIQ results in Total, Home Integration, Social Integration, and Productivity scores. The purposes of this study were to determine change in CIQ scores over time and what burn injury and demographic factors predict CIQ scores. The CIQ scores did not change significantly from 6 to 12 to 24 months postburn injury. Home integration scores were best predicted by sex and living situation; Social Integration scores by marital status; and Productivity scores by functional outcome, burn severity, age, and preburn work factors. The data demonstrate that individuals with burn injuries have significant difficulties with community integration due to burn and nonburn related factors. CIQ scores did not improve over time but improvement may have occurred before the initial 6-month postburn injury follow-up in this study.

Motor cortex activation in hemiparetic stroke patients

100

Little is known about the function of surviving motor cortex after hemiparetic stroke. Though the corticospinal tract may be damaged, function may persist via intact intracortical connections. We probed motor cortex function using paradigms unrelated to genesis of paretic limb movement. Seven patients with chronic post-stroke hemiparesis, including total hand plegia, were studied with functional MRI (fMRI). Brain activation was achieved by alternating between rest and one of several stimuli. For the plegic hand, stimuli were passive index finger movement, or viewing active movements; for the non-plegic hand, active or passive index finger movement. Brain activation maps (p<.001) were generated, after which anatomical landmarks were used to identify regions of interest within non-infarcted tissue. Tasks were rehearsed before fMRI, during which surface EMG leads were placed on 5 muscles in each arm. Patients were median 5 months post-stroke, median age 66 years. Median NIH stroke scale score was 9; Rankin, 3; and arm motor Fugl-Meyer score, 18 (normal=66); Motor Activity Log confirmed no plegic hand use. Studies with excess head movement were excluded, including all plegic hand tasks for 1 patient. Plegic hand tasks (10 studies across 6 patients) activated the stroke hemisphere in all patients, including primary motor cortex (5 patients), primary sensory cortex (5 patients), premotor cortex (4 patients), and supplementary motor area (3 patients). Non-stroke hemisphere was also activated, particularly primary motor cortex (5 patients). In a few instances, EMG disclosed paretic arm muscle activity, but this had no relationship to fMRI activation. Non-plegic hand tasks (9 studies across 7 patients) activated the stroke hemisphere ipsilaterally, including supplementary motor area in all 7 patients, and primary motor cortex in 6 patients. In patients with post-stroke hemiparesis, passive stimulation activates surviving motor cortex regions within the stroke-affected hemisphere. After corticospinal tract damage, motor cortex can still be activated during tasks unrelated to paretic limb movement. The results may suggest therapeutic avenues for improving motor function after stroke.

Ageing, muscle properties and maximal O(2) uptake rate in humans

This paper asks how the decline in maximal O(2) uptake rate (VO(2),max) with age is related to the properties of a key muscle group involved in physical activity - the quadriceps muscles. Maximal oxygen consumption on a cycle ergometer was examined in nine adult (mean age 38.8 years) and 39 elderly subjects (mean age 68.8 years) and compared with the oxidative capacity and volume of the quadriceps. VO(2),max declined with age between 25 and 80 years and the increment in oxygen consumption from unloaded cycling to VO(2),max (delta VO(2)) in the elderly was 45 % of the adult value. The cross-sectional areas of the primary muscles involved in cycling - the hamstrings, gluteus maximus and quadriceps - were all lower in the elderly group. The quadriceps volume was reduced in the elderly to 67 % of the adult value. Oxidative capacity per quadriceps volume was reduced to 53 % of the adult value. The product of oxidative capacity and muscle volume - the quadriceps oxidative capacity - was 36 % of the adult value in the elderly. Quadriceps oxidative capacity was linearly correlated with delta VO(2) among the subjects with the slope indicating that the quadriceps represented 36 % of the VO(2) increase during cycling. The decline in quadriceps oxidative capacity with age resulted from reductions in both muscle volume and oxidative capacity per volume in the elderly and appears to be an important determinant of the age-related reduction in delta VO(2) and VO(2),max found in this study.

Oxidative capacity and ageing in human muscle

This study determined the decline in oxidative capacity per volume of human vastus lateralis muscle between nine adult (mean age 38.8 years) and 40 elderly (mean age 68.8 years) human subjects (age range 25-80 years). We based our oxidative capacity estimates on the kinetics of changes in creatine phosphate content ([PCr]) during recovery from exercise as measured by (31)P magnetic resonance (MR) spectroscopy. A matched muscle biopsy sample permitted determination of mitochondrial volume density and the contribution of the loss of mitochondrial content to the decline in oxidative capacity with age. The maximal oxidative phosphorylation rate or oxidative capacity was estimated from the PCr recovery rate constant (k(PCr)) and the [PCr] in accordance with a simple electrical circuit model of mitochondrial respiratory control. Oxidative capacity was 50 % lower in the elderly vs. the adult group (0.61 +/- 0.04 vs. 1.16 +/- 0.147 mM ATP s(-1)). Mitochondrial volume density was significantly lower in elderly compared with adult muscle (2.9 +/- 0.15 vs. 3.6 +/- 0.11 %). In addition, the oxidative capacity per mitochondrial volume (0.22 +/- 0.042 vs. 0.32 +/- 0.015 mM ATP (s %)(-1)) was reduced in elderly vs. adult subjects. This study showed that elderly subjects had nearly 50 % lower oxidative capacity per volume of muscle than adult subjects. The cellular basis of this drop was a reduction in mitochondrial content, as well as a lower oxidative capacity of the mitochondria with age.

Continuous passive motion for osteoarthritis of the hip: a pilot study

OBJECTIVE

To evaluate whether extended use of continuous passive motion (CPM) may allay the pain of walking, diminish disease effect, and increase the usual walking speed in patients with osteoarthritis (OA) of the hip.

METHODS

This pilot study comprised 21 patients with Kellgren-Lawrence grade 2-4 OA of the hip who used CPM for periods of 1.2 to 7.6 h daily throughout a 12 week trial.

RESULTS

Significant improvements were found in the patients' assessment of pain on visual analog scale, Sickness Impact Profile, self-selected walking speed, and the number of subjects who decreased their medication usage. None of these improvements was related to the radiographic grade of the patients' OA or the daily duration of CPM.

CONCLUSION

Although regular exercise is now routinely recommended to patients with OA, there has been relatively little study of specific exercise programs. As such investigations are undertaken, we believe CPM should be included among the options that are studied.

Exercise: effects on physical functional performance in independent older adults

BACKGROUND

Age-related loss in physiologic capacities contributes to the decline in physical function in the elderly population. Despite the beneficial effects of exercise interventions on maximal physiologic capacity measures, the functional benefits have not been shown in independently living older adults. The objective of this study was to evaluate exercise in independent older adults for significant and meaningful improvements in physical function, not detected by commonly used measures of physical function.

METHODS

In a randomized controlled study, 49 independently living men and women were assigned to either a nonexercise control group (Control; n = 26) or an exercise training group (Exercise; n = 23). Participants (age = 76+/-4) in good general health were recruited from retirement communities or apartments. The combined endurance and strength training was performed at 75% to 80% intensity; the groups met 3 times/week for 6 months of supervised sessions. Outcome measures included physical capacity, health status, and physical function using a newly developed performance test--the Continuous Scale-Physical Functional Performance test (CS-PFP).

RESULTS

Compared to the Control group, the Exercise group showed significant increases in maximal oxygen consumption (11%) and muscle strength (33%). No significant differences were found between groups for changes in the Sickness Impact Profile, SF-36 scales, or the 6-minute walk. However, the CS-PFP score improved significantly in the Exercise group (14%, effect size 0.80).

CONCLUSIONS

Independent older adults gain meaningful functional benefits from several months of exercise training. The public health importance of physical activity may relate not just to its role in preventing decline, but also to its role in enhancing physical function.

Results of 268 pressure sores in 158 patients managed jointly by plastic surgery and rehabilitation medicine

Despite improvements in surgical repair of pressure sores, recurrence rates greater than 80 percent are reported, thus indicating that this difficult problem is not yet solved. Recurrence results in additional hospitalizations and increased medical expenses. Because associated general clinical and social issues are numerous for these patients, our physical medicine and rehabilitation colleagues are active participants in their perioperative medical care. In addition, the Department of Physical Medicine and Rehabilitation also directs a complete postreconstruction rehabilitation and education program for them. The results of surgically repaired pressure sores for patients managed in this collaborative fashion have not been previously reported. Pressure sore patients at the Harborview and University of Washington Medical Centers are evaluated by plastic surgery colleagues together with the Department of Physical Medicine and Rehabilitation. Patients believed to be candidates for complete postoperative rehabilitation are offered surgical repair and constitute this study cohort. Individuals who cannot cooperate with our protocol are treated nonoperatively and are not included in this study. A retrospective analysis of all 158 patients (mean age 34.5 years) operated on for 268 grade III and IV pressure sores between October of 1977 and December of 1989 was performed. Following surgical debridement and reconstruction, patients receive their principal medical care from the Department of Physical Medicine and Rehabilitation service while the Plastic Surgery Department manages the surgical wounds. Graduated patient mobilization is initiated in accord with a mutually agreed upon standardized protocol. New or primary sores numbered 174 (65 percent), and recurrent or secondary sores numbered 94 (35 percent). Mean patient follow-up was 3.7 years. The overall pressure sore recurrence rate (recurrence at the same site) was 19 percent, and the overall patient recurrence rate (previous patient developing a new sore) was 25 percent. Recurrence rates of 22 and 15 percent were noted for primary and secondary pressure sores, respectively. On most recent examination, 131 patients (83 percent) had intact pelvic and perineal skin. These results support a collaborative approach to the management of high-grade pressure sore patients. Our protocol of mutual patient evaluation followed by surgical reconstruction and postoperative rehabilitation yields notably low recurrence rates of both primary and secondary sores. In addition, the high percentage of patients who manifest long-term maintenance of skin integrity demonstrates the excellent education in personal skin and self-care that this approach provides. Not only do patients enjoy successful and durable reconstructive results, but additional hospitalizations and health care expenses implicit to pressure sore recurrence are consequently diminished. This collaborative clinical effort remains our standard of care.

The effect of Medicare's payment system for rehabilitation hospitals on length of stay, charges, and total payments

BACKGROUND

Medicare's system for the payment of rehabilitation hospitals is based on limits derived from a hospital's average allowable charges per patient discharged during a base year. Thereafter, payments are capped but hospitals receive incentive payments if charges per patient are reduced in succeeding years. We hypothesized that per-patient charges would increase during the base year and then decrease in subsequent years. Hospitals would thus have higher reimbursement limits and receive incentive payments for reducing their charges.

METHODS

We analyzed Medicare claims data for 190,921 discharges from 69 rehabilitation hospitals from 1987 through 1994. We compared total charges, length of stay, and interim payments before, during, and after each hospital's base year.

RESULTS

After we controlled for inflation and temporal and seasonal trends, mean charges per patient discharged increased from $25,131 for patients discharged before the base year to $32,167 for patients discharged in the base year (a 28 percent increase, P<0.001) and the mean length of stay increased from 22.1 to 26.7 days (a 21 percent increase, P<0.001). After the base year, mean charges decreased to $29,307 (a 9 percent decrease) and the mean length of stay decreased to 24.0 days (a 10 percent decrease) (P<0.001 for both comparisons). Analysis of data on patients according to diagnosis -- for example, spinal cord injury, brain injury, stroke, amputations and deformities, hip fracture, and arthritis and joint disorders -- showed similar findings for each, with increases in charges and length of stay in the base year, followed by smaller reductions thereafter. For-profit hospitals had greater increases than nonprofit hospitals in their per-patient charges (mean increase, $7,434 vs. $2,929; P<0.001) and length of stay (mean increase, 4.6 vs. 2.3 days, P<0.001) during the base year.

CONCLUSIONS

Although Medicare's reimbursement system for rehabilitation hospitals put an upper limit on total payments, its design was associated with substantial extra costs, including significantly increased payments to hospitals and doctors and increased numbers of hospital days for the average patient.

The effect of strength and endurance training on gait, balance, fall risk, and health services use in community-living older adults

BACKGROUND

The study tested the effect of strength and endurance training on gait, balance, physical health status, fall risk, and health services use in older adults.

METHODS

The study was a single-blinded, randomized controlled trial with intention-to-treat analysis. Adults (n = 105) age 68-85 with at least mild deficits in strength and balance were selected from a random sample of enrollees in a health maintenance organization. The intervention was supervised exercise (1-h sessions, three per week, for 24-26 weeks), followed by self-supervised exercise. Exercise groups included strength training using weight machines (n = 25), endurance training using bicycles (n = 25), and strength and endurance training (n = 25). Study outcomes included gait tests, balance tests, physical health status measures, self-reported falls (up to 25 months of follow-up), and inpatient and outpatient use and costs.

RESULTS

There were no effects of exercise on gait, balance, or physical health status. Exercise had a protective effect on risk of falling (relative hazard = .53, 95% CI = .30-.91). Between 7 and 18 months after randomization, control subjects had more outpatient clinic visits (p < .06) and were more likely to sustain hospital costs over $5000 (p < .05).

CONCLUSIONS

Exercise may have beneficial effects on fall rates and health care use in some subgroups of older adults. In community-living adults with mainly mild impairments in gait, balance, and physical health status, short-term exercise may not have a restorative effect on these impairments.

Decline in isokinetic force with age: muscle cross-sectional area and specific force

Humans produce less muscle force (F) as they age. However, the relationship between decreased force and muscle cross-sectional area (CSA) in older humans is not well documented. We examined changes in F and CSA to determine the relative contributions of muscle atrophy and specific force (F/CSA) to declining force production in aging humans. The proportions of myosin heavy chain (MHC) isoforms were characterized to assess whether this was related to changes in specific force with age. We measured the peak force of isokinetic knee extension in 57 males and females aged 23-80 years, and used magnetic resonance imaging to determine the contractile area of the quadriceps muscle. Analysis of MHC isoforms taken from biopsies of the vastus lateralis muscle showed no relation to specific force. F, CSA, and F/CSA decreased with age. Smaller CSA accounted for only about half of the 39% drop in force that occurred between ages 65-80 years. Specific force dropped about 1.5% per year in this age range, for a total decrease of 21%. Thus, quantitative changes in muscle (atrophy) are not sufficient to explain the strength loss associated with aging.

A comparison of the effects of three types of endurance training on balance and other fall risk factors in older adults

We hypothesized that short-term endurance training improves balance in older adults, if training involves movements that "stress" balance. We tested the hypothesis by looking for a dose-response relationship between movement during exercise and balance improvement. The study was a single-blinded, randomized controlled trial. Subjects were sedentary adults (N = 106) aged 68-85 with at least mild deficits in balance. Exercise groups were: stationary cycle (low movement), walking (medium movement), and aerobic movement (high movement). Subjects attended supervised exercise classes three times a week for three months, followed by self-directed exercise of any type for three months. The primary test of the hypothesis compared changes in balance after three months of supervised exercise. One balance measure (distance walked on a six-meter narrow balance beam) improved in the hypothesized dose-response manner (cycle, 3% improvement; walking, 7% improvement; aerobic movement, 18% improvement: p < 0.02, test of trend). Other balance measures did not improve with exercise. Only walking exercise improved gait speed (by 5%, p < 0.02) and SF-36 role-physical score (by 24%, p < 0.05). VO2max improved with walking (18%, p < 0.004) and aerobic movement (10%, p < 0.01), but improved less with cycling (8%, p > 0.1). Leg strength improved significantly in all exercise groups. The study hypothesis was supported only for one balance measure. Only walking improved at least one measure of all major outcomes (endurance, strength, gait, balance, and health status), suggesting that walking is most useful for all prevention. Cycle exercise appeared least useful.

Continuous-scale physical functional performance in healthy older adults: a validation study

OBJECTIVE

The continuous-scale physical functional performance test (CS-PFP) is an original instrument designed to provide a comprehensive, in-depth measure of physical function that reflects abilities in several separate physical domains. It is based on a concept of physical function as the integration of physiological capacity, physical performance, and psychosocial factors.

SETTING

The test was administered under standard conditions in a hospital facility with a neighborhood setting. The CS-PFP consists of a battery of 15 everyday tasks, ranging from easy to demanding, that sample the physical domains of upper and lower body strength, upper body flexibility, balance and coordination, and endurance. Participants are told to work safely but at maximal effort, and physical functional performance was measured as weight, time, or distance. Scores were standardized and scaled 0 to 12. The test yields a total score and separate physical domain scores.

DESIGN

The CS-PFP was evaluated using 148 older adults-78 community dwellers, 31 long-term care facility residents living independently, and 39 residents with some dependence.

MAIN OUTCOME MEASURES

Maximal physical performance assessment included measures of maximal oxygen consumption (VO2max), isokinetic strength, range of motion, gait, and balance. Psychosocial factors were measured as self-defined health status using the Sickness Impact Profile (SIP), self-perceived function using the Health Survey (SF36), and Instrumental Activities of Daily Living (IADL).

RESULTS

IADL scores were not significantly different among the groups. Test-retest correlations ranged from .84 to .97 and inter-rater reliability from .92 to .99 for the CS-PFP total and 5 domains. Internal consistency was high (Cronbach's alpha, .74 to .97). Both total and individual domain CS-PFP scores were significantly different for the three groups of study participants, increasing with higher levels of independence, supporting construct validity. CS-PFP domain scores were significantly correlated with measures of maximal physical performance (VO2max, strength, etc) and with physical but not emotional aspects of self-perceived function.

CONCLUSION

The CS-PFP is a valid, reliable measure of physical function, applicable to a wide range of functional levels, and having minimal floor and ceiling effect. The total and physical domains may be used to evaluate, discriminate, and predict physical functional performance for both research and clinical purposes.

Factors associated with changes in gait speed in older adults

BACKGROUND

The study addressed whether changes in gait speed in community-dwelling older adults were associated with changes in fitness (strength and aerobic capacity), physical health status, and/or depressive symptoms.

METHODS

The study sample comprised 152 community-dwelling adults aged 68-85 who had participated in an exercise study. Study measures at baseline and 6-month follow-up included gait speed, a leg strength score, maximal aerobic capacity (VO2max), CES-Depression scale, and physical health status (SIP Physical Dimension).

RESULTS

In cross-sectional regression analyses, leg strength, VO2max, weight, and the strength by VO2max interaction term were significant independent predictors of gait speed (R2 = 26%). Based upon the observed 7% increase in VO2max and 8% increase in strength in the exercise groups, the regression model predicted only a 2% (1.5 m/min) increase in gait speed, which did not differ significantly from the observed increase of 0% (.32 m/min). The strongest correlate of change in gait speed was change in CES-D scores (partial R = -.37). Change in physical health status also correlated with change in gait speed (partial R = -.28), while change in fitness did not.

CONCLUSIONS

The results suggest, in the range of fitness of the study sample, that changes in gait speed are related to changes in depressive symptoms and physical health status, but not to modest changes in fitness. A model assuming nonlinear relationships may be appropriate for understanding how strength and aerobic capacity affect gait speed.

From muscle properties to human performance, using magnetic resonance

Our goal is to show how muscle properties can be used to understand the exercise performance limitations of the elderly. We show that magnetic resonance (MR) imaging and spectroscopy are useful for noninvasively characterizing the structural and energetic properties of muscle in vivo. Determination of muscle volume and cross-sectional area is easily and rapidly accomplished by applying quantitative morphometric methods to MR images. New MR spectroscopic techniques provide a noninvasive "biopsy" of the oxidative, glycolytic, and contractile capacities of muscle fibers. We show how the structural and energetic properties measured by MR can be used to define the functional capacity of muscle and the contribution of this capacity to the performance of the whole body (e.g., VO2max). Finally, we relate these laboratory measures of muscle properties and performance to activities meaningful to the functioning of the elderly in everyday life, such as sustained walking and stair climbing.

Psychiatric disorders and functional disability in outpatients with traumatic brain injuries

OBJECTIVE

This study examined psychiatric sequelae of traumatic brain injuries in outpatients and their relation to functional disability.

METHOD

Fifty consecutive outpatients with traumatic brain injuries who came to a brain injury rehabilitation clinic for initial evaluation were examined for DSM-III-R diagnoses with the use of the National Institute of Mental Health Diagnostic Interview Schedule. The patients completed the Medical Outcomes Study Health Survey to assess functional disability and a questionnaire to assess postconcussion symptoms and self-perceptions of the severity of their brain injuries and cognitive functioning.

RESULTS

Thirteen (26%) of the patients had current major depression, and an additional 14 (28%) reported a first-onset major depressive episode after the injury that had resolved. Twelve (24%) had current generalized anxiety disorder, and four (8%) reported current substance abuse. The group with depression and/or anxiety was significantly more impaired than the nondepressed/nonanxious patients according to the Medical Outcomes Study Health Survey measures of emotional role functioning, mental health, and general health perceptions. The depressed/anxious group also rated their injuries as significantly more severe and their cognitive functioning as significantly worse, despite the lack of significant differences in objective measures of severity of injury and Mini-Mental State examination scores. The depressed patients reported significantly more postconcussion symptoms that were increasing in severity over time.

CONCLUSIONS

Depression and anxiety are common in outpatients with traumatic brain injuries. Patients with depression or anxiety are more functionally disabled and perceive their injury and cognitive impairment as more severe. Depressed patients report more increasingly severe postconcussion symptoms.

Classification of the spectrum of mild traumatic brain injury

Mild traumatic brain injury (TBI) is a very common injury, resulting in immediate and possible long-term symptoms. The accurate and consistent definition of mild TBI is important in the initial and rehabilitation management of the injury, and in research concerning mild TBI. A definition of mild TBI has been developed by the Head Injury Interdisciplinary Special Interest Group of the American Congress of Rehabilitation Medicine. Within the spectrum of injury severity in mild TBI there are several classification systems, primarily used in management of acute mild TBI, that breakdown mild TBI into grades of injury severity. These are based upon the presence or absence of mental status changes, amnesia, loss of consciousness, anatomical lesion or neurological deficit.

Selective deep peroneal nerve injury associated with arthroscopic knee surgery

We report 3 cases of isolated deep peroneal nerve injury as a complication of arthroscopic knee surgery. At the level of the knee joint, the deep and superficial peroneal nerves are usually joined as the common peroneal nerve. However, because of the fascicular structure, a partial nerve injury can result in an isolated injury to the deep peroneal nerve fibers. Due to the intraneural topography of the peroneal nerve, electrodiagnostic studies in a partial nerve injury may erroneously indicate a more distal lesion.

Individual variation in contractile cost and recovery in a human skeletal muscle

This study determined the variation among individuals in ATP use during contraction and ATP synthesis after stimulation in a human limb muscle. Muscle energetics were evaluated using a metabolic stress test that separates ATP utilization from synthesis by 31P NMR spectroscopy. Epicutaneous supramaximal twitch stimulation (1 Hz) of the median and ulnar nerves was applied in combination with ischemia of the finger and wrist flexors in eight normal subjects. The linear creatine phosphate (PCr) breakdown during ischemic stimulation defined ATP use (delta PCr per twitch or approximately P/twitch) and was highly reproducible as shown by the relative standard deviation [(standard deviation/mean) x 100] of 11% in three repeated measures. The time constant of the monoexponential PCr change during aerobic recovery represented ATP synthesis rate and also showed a low relative standard deviation (9%). Individuals were found to differ significantly in both mean approximately P/twitch (PCr breakdown rates, 0.29-0.45% PCr per sec or % PCr per twitch; ANOVA, p < 0.001) and in mean recovery time constants (41-74 sec; ANOVA, P < 0.001). This range of approximately P/twitch corresponded with the range of fiber types reported for a flexor muscle. In addition, approximately P/twitch was negatively correlated with a metabolite marker of slow-twitch fiber composition (Pi/ATP). The nearly 2-fold range of recovery time constants agreed with the range of mitochondrial volume densities found in human muscle biopsies. These results indicate that both components involved in the muscle energy balance--oxidative capacity and contractile costs--vary among individuals in human muscle and can be measured noninvasively by 31 P NMR.