Pulmonary function in chronic spinal cord injury: a cross-sectional survey of 222 southern California adult outpatients

Neurogenic respiratory failure

It is uncommon for the lungs to be primarily involved in neurological conditions but severe respiratory problems can arise indirectly. These are usually the result of disorders of central ventilatory control, respiratory muscle weakness, or bulbar involvement. The effects of those disorders can be predicted by an understanding of the nervous control mechanisms and mechanical factors that determine effective ventilation. Awareness of these potential complications, and the increased availability of more advanced diagnostic and monitoring techniques in everyday clinical practice, has resulted in the introduction of specific treatments to try to reduce consequent morbidity and mortality.

Pulmonary function and expiratory flow limitation in acute cervical spinal cord injury

OBJECTIVE

To identify the nature of the changes of respiratory mechanics in patients with middle cervical spinal cord injury (SCI) and their correlation with posture.

DESIGN

Clinical trial.

SETTING

Acute SCI unit.

PARTICIPANTS

Patients with SCI (N=34) at C4-5 level studied within 6 months of injury.

INTERVENTIONS

Patients were assessed by the negative expiratory pressure test, maximal static respiratory pressure test, and standard spirometry.

MAIN OUTCOME MEASURES

The following respiratory variables were recorded in both the semirecumbent and supine positions: (1) tidal expiratory flow limitation (TEFL); (2) airway resistances; (3) mouth occlusion pressure developed 0.1 seconds after occluded inspiration at functional residual capacity (P(0.1)); (4) maximal static inspiratory pressure (MIP) and maximal static expiratory pressure (MEP); and (5) spirometric data.

RESULTS

TEFL was detected in 32% of the patients in the supine position and in 9% in the semirecumbent position. Airway resistances and P(0.1) were much higher compared with normative values, while MIP and MEP were markedly reduced. The ratio of forced expiratory volume in 1 second to forced vital capacity was less than 70%, while the other spirometric data were reduced up to 30% of predicted values.

CONCLUSIONS

Patients with middle cervical SCI can develop TEFL. The presence of TEFL, associated with increased airway resistance, could increase the work of breathing in the presence of a reduced capacity of the respiratory muscles to respond to the increased load. The semirecumbent position and the use of continuous positive airway pressure can be helpful to (1) reduce the extent of TEFL and avoid the opening/closure of the small airways; (2) decrease airway resistance; and (3) maintain the expiratory flow as high as possible, which aids in the removal of secretions.

Maximum voluntary ventilation as a sensitive measure to monitor the ventilatory function in cervical spondylotic myelopathy

STUDY DESIGN

A prospective clinical cohort study.

OBJECTIVES

To test if maximum voluntary ventilation (MVV), which is currently underutilized in diseases, serves for assessing subclinical ventilatory impairment in cervical spondylotic myelopathy (CSM).

SETTING

Kochi Medical School, Japan.

METHODS

We studied ventilatory function in 49 CSM patients and 20 age- and sex-matched control patients with either lumbar stenosis or lower limb osteoarthritis. All patients underwent ventilatory function studies consisting of flow volume curves, vital capacity (VC) and the MVV in 12 s before and after surgery. Tetraparesis was assessed by the functional scale of the Japanese Orthopaedic Association (JOA).

RESULTS

The CSM group had significantly smaller %forced VC , %peak expiratory flow rate (%PEFR) and %MVV than the control group preoperatively. In contrast to the control group, the CSM group showed a significant increase in %MVV from 74.9±18.7% preoperatively to 80.3±19.0% postoperatively (P<0.005), but not in any other ventilatory measures. This postoperative increase in %MVV significantly correlated with the JOA score (r=0.493; P<0.001). As a possible effect of diaphragmatic recovery, the %PEFR significantly increased postoperatively only in patients with the primary site of involvement at or rostral to C3-4.

CONCLUSION

Of the various ventilatory measurements, MVV was most sensitive to changes in tetraparesis in CSM, presumably because MVV, unlike the other ventilatory measures, reflects the coordination in addition to the strength of respiratory muscles.

31st g. Heiner sell lectureship: secondary medical consequences of spinal cord injury

Persons with spinal cord injury (SCI) have secondary medical consequences of paralysis and/or the consequences of extreme inactivity. The metabolic changes that result from reduced activity include insulin resistance with carbohydrate disorders and dyslipidemia. A higher prevalence of coronary artery calcification was found in persons with SCI than that in matched able-bodied controls. A depression in anabolic hormones, circulating testosterone and growth hormone, has been described. Adverse soft tissue body composition changes of increased adiposity and reduced skeletal muscle are appreciated. Immobilization is the cause for sublesional disuse osteoporosis with an associated increased risk of fragility fracture. Bowel dysmotility affects all segments of the gastrointestinal tract, with an interest in better defining and addressing gastroesophageal reflux disease and difficulty with evacuation. Developing and testing more effective approaches to cleanse the bowel for elective colonoscopy are being evaluated. The extent of respiratory dysfunction depends on the level and completeness of SCI. Individuals with higher spinal lesions have both restrictive and obstructive airway disease. Pharmacological approaches and expiratory muscle training are being studied as interventions to improve pulmonary function and cough strength with the objective of reducing pulmonary complications. Persons with spinal lesions above the 6th thoracic level lack both cardiac and peripheral vascular mechanisms to maintain blood pressure, and they are frequently hypotensive, with even worse hypotension with upright posture. Persistent and/or orthostatic hypotension may predispose those with SCI to cognitive impairments. The safety and efficacy of anti-hypotensive agents to normalize blood pressure in persons with higher level cord lesions is being investigated.

Dysphagia in individuals with tetraplegia: incidence and risk factors

BACKGROUND/OBJECTIVE

Dysphagia following cervical spinal cord injury (SCI) can increase risk for pulmonary complications that may delay the rehabilitative process. The objective of this study was to identify risk factors for dysphagia after cervical SCI.

DESIGN

Prospective cohort study.

METHODS

Individuals with cervical SCI within 31 days of injury underwent a bedside swallow evaluation (BSE) followed by a videofluoroscopy swallow study (VFSS) within 72 hours of the BSE. Subjects were diagnosed as having dysphagia if they had positive findings in either BSE or VFSS.

RESULTS

Twenty-nine patients (7 female and 22 male) were enrolled. Of these, 21 (72%) had high cervical tetraplegia (C4 or higher) and 8 (38%) had lower cervical tetraplegia. A tracheostomy was present in 18 (62%) patients; 15 (52%) subjects were on ventilators. Dysphagia was diagnosed in 12 (41%) subjects. Dysphagia was noted in 62% of the subjects with tracheostomy and 53% of the subjects on the ventilator, but only tracheostomy resulted in a statistically significant association with dysphagia (P = 0.047). All three subjects who had nasogastric tubes were diagnosed with dysphagia (P = 0.029). The relationships between dysphagia and gender, high versus low tetraplegia, presence of halo or collar, head injury, and ventilator use were not statistically significant, but age was a significant risk factor (P = 0.028).

CONCLUSIONS

Dysphagia is present in about 41% of individuals with acute tetraplegia. Only age, tracheostomy, and nasogastric tubes were identified as significant risk factors for dysphagia for individuals with tetraplegia. No relationship between dysphagia and level of SCI, spine surgery, collar, and ventilator use was found to exist.

Noninvasive determination of inspiratory pressure in patients with spinal cord injury: what is the best method?

The aim of the study was to evaluate the performance of sniff nasal inspiratory pressure (SNIP) and MIP in individuals with spinal cord injury. We evaluated 26 patients with spinal cord injury. Mean FVC in those with tetraplegia was 52 +/- 19% of predicted, compared with 78 +/- 23% of predicted in those with paraplegia (p < 0.05). In contrast, the percentage of predicted SNIP was lower in those with tetraplegia than in those with paraplegia (p < 0.05). In all participants, SNIP correlated significantly with the level of the injury (r = 0.489; 95% CI: 0.125-0.737). The impact that the greater discriminatory power of SNIP has on the diagnosis of impaired pulmonary function in spinal cord-injured patients should be investigated further.

Neuromuscular adaptations to respiratory muscle inactivity

Cervical spinal cord injury results in significant functional impairment. It is important to understand the neuroplasticity in response to inactivity of respiratory muscles in order to prevent any associated effects that limit functional recovery. Recent studies have examined the mechanisms involved in inactivity-induced neuroplasticity of diaphragm motor units. Both spinal hemisection at C2 (C2HS) and tetrodotoxin (TTX)-induced phrenic nerve blockade result in diaphragm paralysis and inactivity of axon terminals. However, phrenic motoneurons are inactive with C2HS but remain active after TTX. Diaphragm muscle fibers ipsilateral to C2HS display minimal changes post-injury. Neuromuscular transmission is enhanced following C2HS but impaired following TTX. Synaptic vesicle pool size at diaphragm neuromuscular junctions increases after C2HS, but decreases after TTX. Thus, inactivity-induced neuromuscular plasticity reflects specific adaptations that depend on inactivity at the motoneuron rather than at axon terminals or muscle fibers. These results indicate that neuromuscular transmission and functional properties of diaphragm fibers can be maintained after spinal cord injury, providing a substrate for functional recovery and/or specific therapeutic approaches such as phrenic pacing.

Role of neurotrophins in recovery of phrenic motor function following spinal cord injury

Many individuals who sustain a cervical spinal cord injury are unable to maintain adequate ventilation due to diaphragm muscle paralysis. These patients become dependent on mechanical ventilators and this situation is associated with ongoing problems with pulmonary clearance, infections, and lung injury leading to significant morbidity and reduced life expectancy. Therefore, functional recovery of rhythmic phrenic activity and the ability to generate expulsive forces would dramatically affect the quality of life of patients with cervical spinal cord injury. Neurotrophins are very promising in that they have been shown to play an important role in modulating functional neuroplasticity. Specifically, brain-derived neurotrophic factor (BDNF) acting via the tropomyosin-related kinase receptor type B (TrkB) has been implicated in neuroplasticity following spinal cord injury. Our central hypothesis is that functional recovery of rhythmic phrenic activity after cervical spinal cord injury is enhanced by an increase in BDNF/TrkB signaling in phrenic motoneurons, providing a novel therapeutic target for patients.

Pulmonary function and spinal cord injury

Injury to the cervical and upper thoracic spinal cord disrupts function of inspiratory and expiratory muscles, as reflected by reduction in spirometric and lung volume parameters and static mouth pressures. In association, subjects with tetraplegia have decreased chest wall and lung compliance, increased abdominal wall compliance, and rib cage stiffness with paradoxical chest wall movements, all of which contribute to an increase in the work of breathing. Expiratory muscle function is more compromised than inspiratory muscle function among subjects with tetraplegia and high paraplegia, which can result in ineffective cough and propensity to mucus retention and atelectasis. Subjects with tetraplegia also demonstrate heightened vagal activity with reduction in baseline airway caliber, findings attributed to loss of sympathetic innervation to the lungs. Significant increase in airway caliber following inhalation of ipratropium bromide, an anticholinergic agent, suggests that reduction in airway caliber is not due to acquired airway fibrosis stemming from repeated infections or to abnormal hysteresis secondary to chronic inability of subjects to inhale to predicted total lung capacity. Reduced baseline airway caliber possibly explains why subjects with tetraplegia exhibit airway hyperresponsiveness to methacholine and ultrasonically nebulized distilled water. While it has been well demonstrated that bilateral phrenic nerve pacing or stimulation through intramuscular diaphragmatic electrodes improves inspiratory muscle function, it remains unclear if inspiratory muscle training improves pulmonary function. Recent findings suggest that expiratory muscle training, electrical stimulation of expiratory muscles and administration of a long-acting beta(2)-agonist (salmeterol) improve physiological parameters and cough. It is unknown if baseline bronchoconstriction in tetraplegia contributes to respiratory symptoms, of if the chronic administration of a bronchodilator reduces the work of breathing and/or improves respiratory symptoms. Less is known regarding the benefits of treatment of obstructive sleep apnea, despite evidence indicating that the prevalence of this condition in persons with tetraplegia is far greater than that encountered in able-bodied individuals.

Determinants of lung volumes in chronic spinal cord injury

OBJECTIVE

To characterize determinants of lung volumes in chronic spinal cord injury (SCI).

DESIGN

Cross-sectional.

SETTING

VA Boston Healthcare System.

PARTICIPANTS

White men (N=330) with chronic SCI.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Questionnaire responses and measurements of lung volumes.

RESULTS

Adjusted for SCI severity and stature, greater body mass index (BMI) was associated (all P<.05) with lower total lung capacity (TLC) (-38.7 mL x kg(-1) x m(-2)), functional residual capacity (FRC) (-73.9 mL x kg(-1) x m(-2)), residual volume (RV) (-40.4 mL x kg(-1) x m(-2)), and expiratory reserve volume (ERV) (-32.2 mL x kg(-1) x m(-2)). The effect of BMI on RV was most pronounced in quadriplegia (-72 mL x kg(-1) x m(-2)). Lifetime smoking was associated with a greater FRC (5.3 mL/pack-year) and RV (3.1 mL/pack-years). The effects of lifetime smoking were also greatest in quadriplegia (11 mL/pack-year for FRC; 7.8 mL/pack-year for RV). Time since injury, independent of age, was associated with a decrease in TLC, FRC, ERV, and RV (P<.05). Age was not a predictor of TLC once time since injury was considered.

CONCLUSIONS

Determinants of FRC, TLC, ERV, and RV in chronic SCI include factors related and unrelated to SCI. The mechanisms remain to be determined but likely involve the elastic properties and muscle function of the respiratory system and perhaps the effects of systemic inflammation related to adiposity. Addressing modifiable factors such as obesity, muscle stiffness, and smoking may improve respiratory morbidity and mortality in SCI by improving pulmonary function.

Longitudinal change in FEV1 and FVC in chronic spinal cord injury

RATIONALE

Although respiratory dysfunction is common in chronic spinal cord injury (SCI), determinants of longitudinal change in FEV(1) and FVC have not been assessed.

OBJECTIVES

Determine factors that influence longitudinal lung function decline in SCI.

METHODS

A total of 174 male participants (mean age of 49 and 17 yr after injury) completed a respiratory questionnaire and underwent spirometry over an average follow-up of 7.5 years (range, 4-14 yr).

MEASUREMENTS AND MAIN RESULTS

In multivariate models, longitudinal decline in FEV(1) was significantly related to continued smoking, persistent wheeze, an increase in body mass index, and respiratory muscle strength. Aging was associated with an accelerated decline in FEV(1) (for ages <40, 40-60, >60 yr: -27, -37, and -71 ml/yr, respectively). Similar effects were observed for FVC.

CONCLUSIONS

Longitudinal change in FEV(1) and FVC was not directly related to level and severity of SCI, but was attributable to potentially modifiable factors in addition to age. These results suggest that weight control, smoking cessation, trials directed at the recognition and treatment of wheeze, and efforts to improve respiratory muscle strength may slow lung function decline after SCI.

Effects of exercise training and inspiratory muscle training in spinal cord injury: a systematic review

OBJECTIVE

To provide a systematic review of the studies assessing exercise training and inspiratory muscle training (IMT) in individuals for the improved respiratory function of patients with spinal cord injury (SCI).

METHODS

Thirteen studies (5 exercise training, 8 IMT) were identified. Articles were scored for their methodological quality using the Physiotherapy Evidence Database scores and Downs and Black tools for randomized and nonrandomized studies, respectively. Conclusions were based on the most rigorously executed studies using Sackett's levels of evidence.

RESULTS

Study comparison was compromised by diverse research designs; small sample sizes; and heterogeneity of studied populations, protocols, and outcome measures. Based on current literature, there is level 2 evidence supporting exercise training as an intervention to improve respiratory strength and endurance and level 4 evidence to support exercise training as an intervention that might improve resting and exercising respiratory function in people with SCI. There is level 4 evidence to support IMT as an intervention that might decrease dyspnea and improve respiratory function in people with SCI.

CONCLUSIONS

There are insufficient data to strongly support the use of exercise training or IMT for improved respiratory function in people with SCI. There is some evidence of efficacy of both regimens; however, the evidence is not of the best possible quality.

Effect of spinal cord injury on the respiratory system: basic research and current clinical treatment options

Spinal cord injury (SCI) often leads to an impairment of the respiratory system. The more rostral the level of injury, the more likely the injury will affect ventilation. In fact, respiratory insufficiency is the number one cause of mortality and morbidity after SCI. This review highlights the progress that has been made in basic and clinical research, while noting the gaps in our knowledge. Basic research has focused on a hemisection injury model to examine methods aimed at improving respiratory function after SCI, but contusion injury models have also been used. Increasing synaptic plasticity, strengthening spared axonal pathways, and the disinhibition of phrenic motor neurons all result in the activation of a latent respiratory motor pathway that restores function to a previously paralyzed hemidiaphragm in animal models. Human clinical studies have revealed that respiratory function is negatively impacted by SCI. Respiratory muscle training regimens may improve inspiratory function after SCI, but more thorough and carefully designed studies are needed to adequately address this issue. Phrenic nerve and diaphragm pacing are options available to wean patients from standard mechanical ventilation. The techniques aimed at improving respiratory function in humans with SCI have both pros and cons, but having more options available to the clinician allows for more individualized treatment, resulting in better patient care. Despite significant progress in both basic and clinical research, there is still a significant gap in our understanding of the effect of SCI on the respiratory system.

Synaptic vesicle pools at diaphragm neuromuscular junctions vary with motoneuron soma, not axon terminal, inactivity

Both spinal hemisection (SH) at C2 and tetrodotoxin (TTX) phrenic nerve blockade result in diaphragm muscle paralysis and inactivity of the phrenic axon terminals. However, phrenic motoneuron somata are inactive with SH but remain active with TTX phrenic nerve blockade. Neuromuscular transmission failure with repeated activation decreases following SH and increases following TTX phrenic nerve blockade, suggesting that matching (or mismatching) of somal and synaptic inactivities of phrenic motoneurons differentially regulates synaptic vesicle pools at diaphragm neuromuscular junctions. At individual type-identified rat diaphragm presynaptic terminals, the size of the releasable pool of synaptic vesicles was analyzed by fluorescence confocal microscopy of N-(3-triethylammoniumpropyl)-4-(6-(4-(diethylamino)phenyl)hexatrienyl) pyridinium dibromide (FM4-64) uptake and synaptic vesicle density at active zones was determined using transmission electron microscopy. After 14 days of SH and TTX-induced diaphragm muscle inactivity, neuromuscular junction size was not different at type I or IIa fibers, but increased at type IIx and/or IIb fibers (by 51% in SH and 35% in TTX) compared with control. With SH, synaptic vesicle pool size and density increased at presynaptic terminals innervating type I or IIa fibers (17 and 63%, respectively; P<0.001) and type IIx and/or IIb fibers (41 and 31%, respectively; P<0.001) when compared with controls. Following TTX, synaptic vesicle pool size and density decreased by 64 and 17%, respectively, at presynaptic terminals innervating type I or IIa fibers, and by 50 and 36%, respectively, at type IIx and/or IIb fibers (P<0.001, for all comparisons). Thus, matching motoneuron soma and axon terminal inactivity (SH) increases the size and density of releasable synaptic vesicle pools at adult rat diaphragm neuromuscular junctions. Mismatching motoneuron soma and axon terminal inactivities (TTX) results in converse presynaptic adaptations. Inactivity-induced neuromuscular plasticity reflects specific adaptations in the size and density of synaptic vesicle pools that depend on motoneuron soma rather than axon terminal (or muscle fiber) inactivity.

Effect of spinal cord injury on the respiratory system: basic research and current clinical treatment options

Spinal cord injury (SCI) often leads to an impairment of the respiratory system. The more rostral the level of injury, the more likely the injury will affect ventilation. In fact, respiratory insufficiency is the number one cause of mortality and morbidity after SCI. This review highlights the progress that has been made in basic and clinical research, while noting the gaps in our knowledge. Basic research has focused on a hemisection injury model to examine methods aimed at improving respiratory function after SCI, but contusion injury models have also been used. Increasing synaptic plasticity, strengthening spared axonal pathways, and the disinhibition of phrenic motor neurons all result in the activation of a latent respiratory motor pathway that restores function to a previously paralyzed hemidiaphragm in animal models. Human clinical studies have revealed that respiratory function is negatively impacted by SCI. Respiratory muscle training regimens may improve inspiratory function after SCI, but more thorough and carefully designed studies are needed to adequately address this issue. Phrenic nerve and diaphragm pacing are options available to wean patients from standard mechanical ventilation. The techniques aimed at improving respiratory function in humans with SCI have both pros and cons, but having more options available to the clinician allows for more individualized treatment, resulting in better patient care. Despite significant progress in both basic and clinical research, there is still a significant gap in our understanding of the effect of SCI on the respiratory system.

Preliminary reliability and validity of a Spinal Cord Injury Secondary Conditions Scale

BACKGROUND/OBJECTIVE

Although the impact of secondary conditions after spinal cord injury (SCI) on health, well being, and financial burden have been studied, there are psychometrically sound scales of secondary conditions in the extant literature. The use of such scales allows for cross-sample comparison of secondary condition prevalence rates and associations with functional, medical, and psychosocial factors. Thus, the purpose of this study was to evaluate the preliminary reliability of a SCI secondary conditions scale.

METHODS

The Spinal Cord Injury Secondary Conditions Scale (SCI-SCS) is a 16-item scale based on the Seekins Secondary Conditions Scale. Sixty-five individuals with SCI completed written surveys at 5 time-points over 2 years.

RESULTS

Internal consistency across each of the time-points exceeded 0.76; test-retest reliability ranged from 0.569 to 0.805. Convergent validity was assessed with 6 physical functioning items from the SF-12. Spearman (coefficients were all statistically significant and ranged from 0.317 (accomplished less because of health problems) to 0.644 (pain). The most prevalent secondary conditions were chronic pain, joint and muscle pain, and sexual dysfunction.

CONCLUSIONS

Preliminary testing of the SCI-SCS suggests that it is a reliable and valid scale, and further development (ie, factor analysis, item revision) and examination of validity are recommended with larger and more diverse SCI samples.

Determinants of forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC in chronic spinal cord injury

OBJECTIVE

To assess factors that influence pulmonary function, because respiratory system dysfunction is common in chronic spinal cord injury (SCI).

DESIGN

Cross-sectional cohort study.

SETTING

Veterans Affairs Boston SCI service and the community.

PARTICIPANTS

Between 1994 and 2003, 339 white men with chronic SCI completed a respiratory questionnaire and underwent spirometry.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), and FEV(1)/FVC.

RESULTS

Adjusting for SCI level and completeness, FEV(1) (-21.0 mL/y; 95% confidence interval [CI], -26.3 to -15.7 mL/y) and FVC (-17.2 mL/y; 95% CI, -23.7 to -10.8 mL/y) declined with age. Lifetime cigarette use was also associated with a decrease in FEV(1) (-3.8 mL/pack-year; 95% CI, -6.5 to -1.1 mL/pack-year), and persistent wheeze and elevated body mass index were associated with a lower FEV(1)/FVC. A greater maximal inspiratory pressure (MIP) was associated with a greater FEV(1) and FVC. FEV(1) significantly decreased with injury duration (-6.1 mL/y; 95% CI, -11.7 to -0.6 mL/y), with the greatest decrement in the most neurologically impaired. The most neurologically impaired also had a greater FEV(1)/FVC, and their FEV(1) and FVC were less affected by age and smoking.

CONCLUSIONS

Smoking, persistent wheeze, obesity, and MIP, in addition to SCI level and completeness, were significant determinants of pulmonary function. In SCI, FEV(1), FVC, and FEV(1)/FVC may be less sensitive to factors associated with change in airway size and not reliably detect the severity of airflow obstruction.

Changes in Physical Capacity During and After Inpatient Rehabilitation in Subjects With a Spinal Cord Injury

OBJECTIVE

To assess changes in physical capacity and its determinants in persons with a spinal cord injury.

DESIGN

Prospective cohort study. Measurements at the start of active rehabilitation (t1), 3 months later (t2), at discharge (t3), and 1 year after discharge (t4).

SETTING

Eight rehabilitation centers in The Netherlands.

PARTICIPANTS

A total of 186 subjects at t1 and 123 subjects at t4.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Peak aerobic power output (POpeak), peak oxygen uptake (V(O2)peak), muscle strength of the upper extremity (manual muscle test, handheld dynamometry), and respiratory function (forced expiratory flow per second, forced vital capacity).

RESULTS

Random coefficient analysis demonstrated that the POpeak, V(O2)peak, strength, and respiratory function improved during inpatient rehabilitation, and that V(O2)peak, strength, and respiratory function continued to improve after discharge. Age, sex, and level and completeness of lesion were determinants of the change in components of physical capacity.

CONCLUSIONS

Physical capacity improves during inpatient rehabilitation, and some components continue to improve after discharge. Subpopulations have a different level of (change in) physical capacity. The components of physical capacity are related; intervention studies are needed to confirm whether training 1 component could improve another component.

Respiratory muscle training in persons with spinal cord injury: a systematic review

The purpose of this paper was to review the effectiveness of respiratory muscle training (RMT) on respiratory muscle strength and endurance, pulmonary function, quality of life, respiratory complications and exercise performance in persons with spinal cord injury. A MEDLINE (National Library of Medicine, Bethesda, MD, USA) database was used for selection of the literature (from 1980 to November 2004), and relevant references from peer-reviewed articles were retrieved as well. Studies investigating the effects of RMT (i.e. resistive breathing weight lifting or normocapnic hyperpnea) in persons with spinal cord injury were selected. Two independent reviewers investigated controlled studies for methodological quality by using a modification of the framework for methodological quality. Methodological quality ranged between 15 and 29 (maximal feasible score=40). Twenty-three papers were retrieved and six controlled trials were kept for further analysis. A meta-analysis and calculation of effect-size of each individual study and weighted summary effect-size was intended. However, unreported data and heterogeneity in outcome variables did not allow performing a meta-analysis. From the systematic review it is concluded that RMT tended to improve expiratory muscle strength, vital capacity and residual volume. Insufficient data was available to make conclusions concerning the effects on inspiratory muscle strength, respiratory muscle endurance, quality of life, exercise performance and respiratory complications.

Effect of neuromuscular electrical stimulation on cough capacity and pulmonary function in patients with acute cervical cord injury

OBJECTIVE

To assess the effectiveness of neuromuscular electrical stimulation (NMES) on cough capacity and prevention of pulmonary complication in patients with acute cervical cord injury.

DESIGN

A randomized controlled trial.

SUBJECTS

Twenty-six tetraplegic patients with cervical spinal cord injury, 13 in the NMES therapy group and 13 in the control group.

METHODS

NMES was applied to the clavicular portion of the pectoralis major and abdominal muscle. Pulmonary function tests were performed before and after therapy, and at 3 months and 6 months follow-up. The pulmonary complications in this 6-month follow-up period were also recorded.

RESULTS

After the 4-week therapy, and at 3 months and 6 months follow-up testing, patients in the NMES therapy group displayed significant improvement in their peak expiratory flow, forced expiratory volume in 1 second, forced vital capacity, maximal expiratory pressure and maximal inspiratory pressure, compared with those in the control group (p<0.05). Patients in the NMES therapy group also had fewer pulmonary complications in the follow-up period.

CONCLUSION

NMES over the pectoralis and abdominal muscles might improve cough capacity and pulmonary function in cervical spinal cord injury with tetraplegia. This improvement might last for 6 months. With this improvement, pulmonary complications were reduced.

Physical capacity in wheelchair-dependent persons with a spinal cord injury: a critical review of the literature

STUDY DESIGN

Review of publications.

OBJECTIVE

To assess the level of physical capacity (peak oxygen uptake, peak power output, muscle strength of the upper extremity and respiratory function) in wheelchair-dependent persons with a spinal cord injury (SCI).

SETTING

Erasmus MC, University Medical Centre Rotterdam, The Netherlands.

METHODS

Pubmed (Medline) search of publications from 1980 onwards. Studies were systematically assessed. Weighted means were calculated for baseline values.

RESULTS

In tetraplegia, the weighted mean for peak oxygen uptake was 0.89 l/min for the wheelchair exercise test (WCE) and 0.87 l/min for arm-cranking or hand-cycling (ACE). The peak power output was 26 W (WCE) and 40 W (ACE). In paraplegia, the peak oxygen uptake was 2.10 l/min (WCE) and 1.51 l/min (ACE), whereas the peak power output was 74 W (ACE) and 85 W (WCE). In paraplegia, muscle strength of the upper extremity and respiratory function were comparable to that in the able-bodied population. In tetraplegia muscle strength varied greatly, and respiratory function was reduced to 55-59% of the predicted values for an age-, gender- and height-matched able-bodied population.

CONCLUSIONS

Physical capacity is reduced and varies in SCI. The variation between results is caused by population and methodological differences. Standardized measurement of physical capacity is needed to further develop comparative values for clinical practice and rehabilitation research.

Respiratory effects of combined truncal and abdominal support in patients with spinal cord injury

OBJECTIVE

To determine whether a custom girdle, designed to provide truncal stability and abdominal support, will improve pulmonary function, enhance inspiratory muscle activity, and reduce the sensation of respiratory effort in patients with spinal cord injury (SCI).

DESIGN

Pulmonary function, transdiaphragmatic pressure time product (PTP di ), twitch (Tw Pdi) and maximal transdiaphragmatic pressures (Pdi), and perception of respiratory effort (Borg Rating of Perceived Exertion score) were measured with and without an abdominal girdle in a seated position.

SETTING

Rehabilitation hospital.

PARTICIPANTS

Ten patients with posttrauma SCI (injury level, C5-T6).

INTERVENTION

Application of the abdominal girdle.

MAIN OUTCOME MEASURES

Borg score and measures of lung volumes, dynamic abdominal compliance, and Tw Pdi and maximal Pdi.

RESULTS

Wearing of the girdle was associated with a lower Borg score (P = .002) and reduced functional residual capacity (P = .006) but increased inspiratory capacity (P = .02) and forced vital capacity (P = .02). Although there was a decrease in dynamic abdominal compliance (P < .001) and an increase in PTP di (P = .02), this was accompanied by an increase in both Tw Pdi (P = .02) and maximal Pdi (P = .03). CONCLUSIONS The custom girdle reduced the sensation of respiratory effort in patients with SCI by optimizing the operating lung volumes and decreasing abdominal compliance, which enhanced diaphragm performance.

The combined effects of controlled breathing techniques and ventilatory and upper extremity muscle exercise on cardiopulmonary responses in patients with spinal cord injury

This study investigated the effects of controlled breathing techniques and ventilatory and upper extremity muscle exercise on cardiopulmonary and metabolic functions and exercise tolerance in patients with spinal cord injury (SCI). The design of the study was prospective and was a before-after trial. Twenty patients with SCI were included in the study. Resting pulmonary functions were assessed spirometrically. Cardiopulmonary and metabolic responses to maximum exercise were determined with an electronically braked arm crank ergometer. The expired gases during this exercise were collected and analysed using a computerized gas analysis system. Patients with SCI participated in a 6-week ventilatory and upper extremity muscle exercise program for 1 h, three times per week. At the end of the exercise program, we observed significant improvement in spirometric values, peak oxygen uptake, time to fatigue, peak power output and minute ventilation compared with pre-training values for the patients.

Breathing and the support of blood pressure after spinal cord injury

STUDY DESIGN

Literature review.

OBJECTIVES

The recognized effect of breathing on venous return and cardiac output has not been assessed in the spinal cord injury (SCI) patient. To test this effect indirectly, the breathing capacity and blood pressure have been compared at various levels of SCI.

SETTING

SCI service, Massachusetts, USA.

METHODS

Spinal cord-injured subjects with complete motor paralysis were studied. The forced vital capacity (FVC) (one study, 455 subjects, 91% male) was compared with the mean blood pressure (MBP) (one study, 461 subjects, 100% male) of subjects by level of paralysis.

RESULTS

For lumbar to cervical levels of paralysis, FVC and MBP each diminish progressively. To compare FVC directly with MBP by level of paralysis, r=0.85, P<0.001.

CONCLUSION

Breathing capacity is correlated with blood pressure in SCI patients.

Long-Term Treatment of Sleep Apnea in Persons with Spinal Cord Injury

OBJECTIVE

Although numerous studies have documented a high prevalence of sleep apnea in persons with spinal cord injury, relatively little has been published regarding treatment of sleep apnea in this population. The purpose of this study was to describe long-term treatment outcomes and side effects of sleep apnea treatment in persons with spinal cord injury.

DESIGN

Descriptive, postal mail survey to spinal cord injury individuals with sleep apnea followed by a Veterans Affairs Spinal Cord Injury Service.

RESULTS

The response rate to the mailed survey was 54%, with complete surveys obtained from 40 individuals with spinal cord injury and sleep apnea. The majority of participants (93%) had been diagnosed with sleep apnea through routine clinical care, and patients had been diagnosed a mean of 4 yrs earlier. Continuous positive airway pressure was the most commonly used treatment. Continuous positive airway pressure was tried by 80% of patients, and of these, 63% continued to use continuous positive airway pressure, with mean usage 6.5 nights per week and 6.9 hrs per night. Continuous positive airway pressure was rated as beneficial in comparison with its side effects. The most common side effects were nasal congestion and mask discomfort.

CONCLUSION

Many spinal cord injury individuals with sleep apnea become long-term users of continuous positive airway pressure and perceive a subjective benefit from the treatment.

Cheyne-Stokes respiration, periodic circulation, and pulsus alternans in spinal cord injury patients

STUDY DESIGN

Case reports.

OBJECTIVES

To describe Cheyne-Stokes respiration (CSR) and associated circulatory abnormalities in three patients with spinal cord lesions.

SETTING

Veterans Administration Hospital, USA.

SUBJECTS

One paraplegic patient with coronary artery disease in congestive heart failure, one tetraplegic patient with alcoholic cardiomyopathy and postural hypotension, and one tetraplegic complete patient with cardiomegaly, severe aortic atherosclerosis, and postural hypotension.

METHODS

Breathing activity was measured with a nasal thermistor or abdominal stretch transducer. Cardiac activity was estimated with a photoelectric sensor for cutaneous blood flow placed on the forehead or a piezoelectric transducer for pressure positioned over an artery or the cardiac apex. Tracings were drawn on a strip chart recorder. The subjects were at rest in semireclining positions.

RESULTS

Survey times were 17-21 min, and cycling periods were 41-72 s. Periodic changes in the depth of breathing were accompanied by periodic changes in amplitude of forehead cutaneous pulse, blood pressure, or apical cardiac impulse in all patients. Peak circulation occurred at or following peak respiration. In addition, cyclical pulsus alternans occurred in two patients.

CONCLUSION

Three spinal cord injury patients sustained CSR and circulatory periodicity associated with cardiac disease and postural hypotension.

Recurrent pulmonary embolism and pulmonary hypertension in chronic tetraplegia

STUDY DESIGN

Case report.

OBJECTIVE

To describe an unusual case of progressive pulmonary hypertension due to recurrent pulmonary embolism in a chronically paralyzed spinal cord injury patient.

SETTING

Veterans Administration Hospital, West Roxbury, MA, USA.

SUBJECT

A 57-year-old man, tetraplegic, sensory incomplete and motor complete for 30 years due to a diving accident, complained of lightheadedness and shortness of breath intermittently for 7 years. Examination during the latest episode revealed anxiety, confusion, respirations 28 per min, blood pressure 80/60 mmHg, and arterial pH 7.41, P(CO2) 28 mmHg, P(O2) 95 mmHg on 2 l of oxygen. A chest film 2 weeks earlier had revealed a right-sided cutoff of pulmonary vasculature; the current film showed right-sided pleural effusion. Review of EKGs showed a trend of increasing right axis deviation with recovery and recurrences during the previous 9 years and a current incomplete right bundle branch block with clockwise rotation and inverted T waves in V1-4. Computerized tomography with contrast material revealed small pulmonary emboli, but only in retrospect. The patient died shortly after scanning.

AUTOPSY

The pulmonary arteries were free of thromboemboli on gross examination but medium and small-sized arteries were constricted or obliterated with thrombotic material microscopically. The estimated ages of the thromboemboli ranged from days to years. The right ventricle was hypertrophied; the coronary arteries were patent.

CONCLUSION

Recurrent pulmonary emboli resulted in chronic pulmonary hypertension and eventual death in a patient with chronic tetraplegia.

What the rehabilitation professional and the consumer need to know

Many people with disabilities from early in life (eg, cerebral palsy,spinal cord injury, and polio) are beginning to live into middle and late life. Recent evidence indicates that these individuals often do not age in a typical manner. A large proportion of these people develop new medical, functional, and support problems by the time they reach their late 40s and early 50s. This article reviews many of those changes and points to some ways to help intervene. Changes in rehabilitation education and programs need to begin to incorporate these recent findings.

Aging with spinal cord injury

The years after SCI may be associated with acceleration of the aging process because of diminished physiologic reserves and increased demands on functioning body systems. Clinicians with expertise in the treatment and prevention of SCI-specific secondary complications need to collaborate with gerontologists and primary care specialists and need to invest in the training of future physicians to ensure a continuum of accessible, cost-effective, and high-quality care that meets the changing needs of the SCI population. Managed care payers often do not adequately cover long-term disability needs to prevent secondary SCI-specific complications. In this era of increasing accountability, evidence-based clinical practice guidelines are needed to document scientific evidence and professional consensus to effectively diagnose, treat, and manage clinical conditions; to reduce unnecessary testing and procedures; and to improve patient outcomes. Longitudinal research is needed to minimize cohort effects that contribute to misinterpretation of cross-sectional findings as representative of long-term changes in health and functioning. However, longitudinal studies confound chronologic age, time since injury, and environmental change. Thus, time-sequential research, which controls for such confounding effects, is essential, as is research on the effects of gender,culture, and ethnicity. If we consider how much progress has been made over the past 50 years with respect to SCI mortality related to infectious disease, we can expect to achieve even greater progress against the effects of aging in the next 50 years. Recent developments in molecular biology regarding growth and neuro-trophic factors are bringing us closer to the goal of repairing the damaged spinal cord. The challenge remains for rehabilitation professionals to provide the most comprehensive and holistic approach to long-term follow-up, with an emphasis on health promotion and disease prevention, to postpone functional decline and enhance QOL.

Effects of a wheelchair ergometer training programme on spinal cord-injured persons

STUDY DESIGN

Before and after investigation of the effects of a wheelchair ergometer Training programme.

OBJECTIVE

To investigate the effects of an original interval-training programme on work capacity and cardiorespiratory variables with spinal cord-injured persons (SCIP's) on a wheelchair-specific ergometer.

SETTING

BESANCON, FRANCE.

METHODS

Seven SCIP's (male) performed 45 min of wheelchair ergometry three times per week, for 6 weeks. Training effects on maximal dynamic performance and endurance capacity were studied by comparison of performance and cardiorespiratory responses observed during both a maximal progressive test (10 W/2 min) and the same training session performed before and after training.

RESULTS

Training induced significant improvements in maximal tolerated power (+19.6%), in peak oxygen consumption (VO2,+16%), and in oxygen pulse (O2p,+18.7%). At ventilatory threshold, significant improvements were also observed in power output (+63%), VO2VT(+ 34.1), ventilation VEVT(+ 37.1%), and V2pVT(+ 19.9% ). Heart rate and ventilation were significantly lower (-11 and -14.6%, respectively) after training at the same work rate, while VO2 was unchanged. Between the first and the last training session, the total physical work was improved by 24.7%, whereas heart rate was unchanged.

CONCLUSION

An interval-training programme individualised to each paraplegic subject using a wheelchair ergometer can significantly improve the fitness level and endurance capacity.

Breathlessness associated with abdominal spastic contraction in a patient with C4 tetraplegia: a case report

A tetraplegic patient with C4 cervical cord injury reported breathlessness during episodes of spastic contraction of the abdominal muscles. To determine the mechanism, we performed electrophysiologic testing of the phrenic nerves. We measured abdominal pressure, esophageal pressure, and transdiaphragmatic pressure (Pdi) during a maximal inspiratory effort (Pdi max), a maximal sniff maneuver (sniff Pdi) during resting breathing, and during the episodes of breathlessness. Electrophysiologic testing of the phrenic nerves showed axonal neuropathy on the left. Sniff Pdi and Pdi max were 38cmH(2)O and 42cmH(2)O, respectively. Transient spastic contractions of abdominal muscles were associated with an increase in abdominal pressure greater than 30cmH(2)O, with a decrease in abdominal volume; this rise in abdominal pressure was transmitted to the esophageal pressure. Inspiration became effective only when esophageal pressure fell below the resting baseline value. Achieving this decrease required an increase in inspiratory effort, characterized by swings in esophageal pressure and Pdi of 30cmH(2)O and 40cmH(2)O (approximately 100% of Pdi max), respectively. During these periods, minute ventilation was markedly reduced. This is the first report that spastic abdominal muscle contractions can impose a significant load on the diaphragm, uncovering moderate diaphragmatic weakness. This has important clinical implications; abolition of the spastic abdominal muscle contraction in this patient completely resolved her intermittent respiratory symptoms.

Maximizing health in menopausal women with disabilities

There are nearly 30 million women with disabilities in the United States. Of these, more than 16 million are over the age of 50. Years ago, women with disabilities did not commonly live to the age of menopause, and, if they did, they reached this stage of life in a very debilitated condition. Now, women with disabilities are entering their mature years as active members of society who can look forward to productive futures. Because the health needs of women with disabilities might differ from those of other women, special attention should be focused on how physiological changes of perimenopausal and menopausal states affect this population. In addition to functional changes that might affect menopausal women with disabilities, basic health maintenance issues may be adversely affected by environmental factors. Physical barriers can influence compliance with preventive health screening that is essential in aging populations. Treatment options might need to be tailored to the individual. The disabling condition itself may progress, resulting in secondary conditions requiring creative interventions. A comprehensive evaluation and the development of a suitable management plan, which takes into account the multifactorial nature of aging as a disabled woman, are essential in delivering optimal care to this population.

Spinal cord injury medicine. 2. Medical complications after spinal cord injury: Identification and management

This is a self-directed learning module that reviews medical complications associated with spinal cord injury (SCI). It is part of a chapter on SCI medicine in the Self-Directed Physiatric Educational Program for practitioners and trainees in physical medicine and rehabilitation. This article includes discussion of common medical complications that impact rehabilitation and long-term follow-up for individuals with SCI. Issues addressed include the rehabilitation approach to SCI individuals with pressure ulcers, unilateral lower-extremity swelling (deep venous thrombosis, heterotopic ossification, fractures), along with the pathophysiology, assessment, and treatment of spasticity, autonomic dysreflexia, orthostatic hypotension, and pain.

OVERALL ARTICLE OBJECTIVE

To describe diagnostic and treatment approaches for medical complications common to individuals with SCI.

Forced vital capacity in two large outpatient populations with chronic spinal cord injury

OBJECTIVE

To determine the expected vital capacity in persons with chronic spinal cord injury (SCI) in relation to injury level, completeness of injury, smoking and duration of injury, as an aid to diagnosis and management of respiratory complications.

SETTING

A New York City veterans' hospital and a Los Angeles public rehabilitation hospital.

METHODS

Case series from the two hospitals were pooled. Participants (adult outpatients with SCI of duration >1 year, not ventilator-dependent) were evaluated by conventional forced expiratory spirometry. Cross-sectional analysis was performed, using multiple regression, on the entire population and defined subgroups. The principal outcome measure was forced vital capacity (FVC).

RESULTS

In the subjects with complete-motor lesions, FVC ranged from near 100% of normal predicted values in the group with low paraplegia, to less than 50% in those with high tetraplegia. Incomplete lesions mitigated FVC loss in tetraplegia. In subjects with paraplegia, longer duration of injury was associated with greater loss, and smoking-related loss was evident at older but not at younger ages, presumably due to greater pack years in older subjects.

CONCLUSIONS

Vital capacity/SCI level relationships determined here may have diagnostic and prognostic value. Smoking-related FVC loss is important in persons with SCI as in others, although at higher levels it may be obscured by SCI-related loss.