A multicenter pilot study of a bronchial valve for the treatment of severe emphysema.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) affects millions of people and has limited treatment options. Surgical treatments for severe COPD with emphysema are effective for highly selected patients. A minimally invasive method for treating emphysema could decrease morbidity and increase acceptance by patients. OBJECTIVE: To study the safety and effectiveness of the IBV(R) Valve for the treatment of severe emphysema. METHODS: A multicenter study treated 91 patients with severe obstruction, hyperinflation and upper lobe (UL)-predominant emphysema with 609 bronchial valves placed bilaterally into ULs. RESULTS: Valves were placed in desired airways with 99.7% technical success and no migration or erosion. There were no procedure-related deaths and 30-day morbidity and mortality were 5.5 and 1.1%, respectively. Pneumothorax was the most frequent serious device-related complication and primarily occurred when all segments of a lobe, especially the left UL, were occluded. Highly significant health-related quality of life (HRQL) improvement (-8.2 +/- 16.2, mean +/- SD change at 6 months) was observed. HRQL improvement was associated with a decreased volume (mean -294 +/- 427 ml, p = 0.007) in the treated lobes without visible atelectasis. FEV(1), exercise tests, and total lung volume were not changed but there was a proportional shift, a redirection of inspired volume to the untreated lobes. Combined with perfusion scan changes, this suggests that there is improved ventilation and perfusion matching in non-UL lung parenchyma. CONCLUSION: Bronchial valve treatment of emphysema has multiple mechanisms of action and acceptable safety, and significantly improves quality of life for the majority of patients.

A microcontroller system for investigating the catch effect: functional electrical stimulation of the common peroneal nerve.

Correction of drop foot in hemiplegic gait is achieved by electrical stimulation of the common peroneal nerve with a series of pulses at a fixed frequency. However, during normal gait, the electromyographic signals from the tibialis anterior muscle indicate that muscle force is not constant but varies during the swing phase. The application of double pulses for the correction of drop foot may enhance the gait by generating greater torque at the ankle and thereby increase the efficiency of the stimulation with reduced fatigue. A flexible controller has been designed around the Odstock Drop Foot Stimulator to deliver different profiles of pulses implementing doublets and optimum series. A peripheral interface controller (PIC) microcontroller with some external circuits has been designed and tested to accommodate six profiles. Preliminary results of the measurements from a normal subject seated in a multi-moment chair (an isometric torque measurement device) indicate that profiles containing doublets and optimum spaced pulses look favourable for clinical use.

Biomechanical approaches applied to the lower and upper limb for the measurement of spasticity: a systematic review of the literature.

PURPOSE: To review and characterise biomechanical approaches for the measurement of spasticity as one component of the upper motor neurone syndrome. METHOD: Systematic literature searches based on defined constructs and a four-step review process of approaches used or described to measure spasticity, its association with function or associated phenomena. Most approaches were limited to individual joints and therefore, to reflect this trend, references were grouped according to which body joint(s) were investigated or whether it addressed a functional activity. For each joint, references were further sub-divided into the types of measurement method described. RESULTS: A database of 335 references was established for the review process. The knee, ankle and elbow joints were the most popular, perhaps reflecting the assumption that they are mono-planar in movement and therefore simpler to assess. Seven measurement methods were identified: five involving passive movement (manual, controlled displacement, controlled torque, gravitational and tendon tap) and two involving active movement (voluntary and functional). Generally, the equipment described was in an experimental stage and there was a lack of information on system properties, such as accuracy or reliability. Patient testing was either by cohort or case studies. The review also conveyed the myriad of interpretations of the concept of spasticity. CONCLUSIONS: Though biomechanical approaches provide quantitative data, the review highlighted several limitations that have prevented them being established as an appropriate method for clinical application to measure spasticity.

Theoretical and methodological considerations in the measurement of spasticity.

PURPOSE: To discuss the measurement of spasticity in the clinical and research environments, make recommendations based on the SPASM reviews of biomechanical, neurophysiological and clinical methods of measuring spasticity and indicate future developments of measurement tools. METHOD: Using the results of the systematic reviews of the biomechanical, neurophysiological and clinical approaches, methods were evaluated across three dimensions: (1) validity, reliability and sensitivity to change; (2) practical quality such as ease of use and (3) qualities specific to the measurement of spasticity, for example ability to be applied to different muscle groups. Methods were considered in terms of applicability to research and clinical applications. RESULTS: A hierarchy of measurement approaches was identified from highly controlled and more objective (but unrelated to function) to ecologically valid, but less objective and subject to contamination from other variables. The lack of a precise definition of spasticity may account for the problem of developing a valid, reliable and sensitive method of measurement. The reviews have identified that some tests measure spasticity per se, some phenomena associated with spasticity or consequential to it and others the effect of spasticity on activity and participation and independence. CONCLUSIONS: Methods appropriate for use in research, particularly into the mechanism of spasticity did not satisfy the needs of the clinician and the need for an objective but clinically applicable tool was identified. A clinical assessment may need to generate more than one 'value' and should include evaluation of other components of the upper motor neurone syndrome. There is therefore a need for standardized protocols for 'best practice' in application of spasticity measurement tools and scales.

Recruitment by motor nerve root stimulators: significance for implant design.

Three paraplegics have been implanted with stimulators of the lumbar anterior roots. Twelve roots were trapped in slots, each with three electrodes, a central cathode and two anodes, but the anodes in all the slots were connected together to reduce the number of wires. Cross-talk between roots was observed at lower levels than expected. Cross-talk was assessed from the ratio of the root's threshold to the threshold of the contralateral response (expected ratio: 72). Two hypothetical reasons for this low ratio were: that the cathode current was not equally shared by the anodes; or that the contralateral responses were reflex. Experiments showed that neither explanation was valid. The ratio of the contralateral to ipsilateral threshold for individual slots (K(1)) was sometimes low because the ipsilateral threshold was high. By taking the ratio of the lowest contralateral response to lowest ipsilateral response, for all roots in each subject (K(2)), the ratio should approach the theoretical value. However, for the two subjects with small slots, it was 7.9 and 15.3, much less than 72, suggesting that the original theory was incorrect. Approximate calculations of the activation function suggest that the reason may be that roots which run close to a slot, but not through it, may pass through a virtual anode region outside the ends of the slots, and that anodal break stimulation in those regions causes the cross-talk. Our estimate is that this cross-talk would be expected to occur at intensities above 5.3 times the cathodal threshold. If the roots are stimulated in pairs, below the levels of cross-talk, experimental results show that the moments obtained in response are additive to within 5%.

Reversible left ventricular dysfunction simulating a myocardial infarction after pericardiectomy.

A 39 year old man with postoperative constrictive pericarditis after pericardiectomy developed major left ventricular systolic dysfunction with an anterior wall infarct pattern on ECG but no regional wall motion abnormalities by echocardiography or serum enzymatic evidence of a myocardial infarction. The left ventricular dysfunction resolved over two weeks with supportive treatment. It is postulated that this patient's transient left ventricular dysfunction and ECG changes were caused by myocardial inflammation and oedema induced by operative trauma during pericardiectomy.

Indices to describe different muscle activation patterns, identified during treadmill walking, in people with spastic drop-foot.

This study was concerned with individuals who were unable to effectively dorsiflex their ankle when walking, as a result of a lesion of the central nervous system (CNS). Indices that categorise and quantify different patterns of calf and anterior tibial muscle activation patterns during treadmill walking have been derived from a sample of fifteen individuals with established hemiplegia following stroke and twelve age-matched individuals without impairment. As subjects walked on a treadmill, force sensitive foot-switches under the heel and first metatarsal head allowed EMG signals from the calf and anterior tibial muscles to be related to phases of the gait cycle. Normal activation periods for each muscle group were identified as percentiles of the gait cycle and indices for muscle activation periods were derived using ratios of integrated EMG during selected periods. Indices were derived that identified statistically significant differences, between normal and hemiplegic subjects, in calf activation during both push-off phase (P<0.001) and early stance phase (P<001), but not activation of tibialis anterior during swing (P=0.325) Observation suggested that integrated tibialis anterior activity during swing phase in hemiplegic subjects was not dissimilar to normal subjects, but the profile in hemiplegic subjects tended to lack the normal second peak of activity at initial foot contact. The reasons for drop-foot were shown to be varied and complex. The indices defined may be useful for directing therapy and measuring outcome.

XAFS studies of the formation of cobalt silicide on (square root of 3 x square root of 3) SiC(0001).

Thin Co films (1-8 nm) were directly, sequentially, and co-deposited with Si (3.6-29.2 nm) on the (square root of 3 x square root of 3)-R30 degrees reconstruction of 6H-SiC(0001). The films were annealed over a temperature range of 823-1373K and investigated with XAFS, XPS, AES and AFM. After annealing up to 1373K directly deposited Co films do not transform entirely to cobalt disilicide and C segregation is observed on the surface of the films. On the other hand, sequentially and co-deposited films do form cobalt disilicide after annealing at 823K, but also show islanding after annealing at 923K.

Total esophageal reconstruction using a tubed parascapular free flap.

A method for total esophageal reconstruction when intestinal options are no longer available is presented. The technique described utilizes the parascapular microsurgical free flap, which is tubed and interposed between the cervical esophagus and the gastric remnant in the abdomen. The technique involves a well-recognized microsurgical flap and may be added to the armamentarium for total esophageal reconstruction.

Results from bone mineral density scans in twenty-two complete lesion paraplegics.

STUDY DESIGN: The bone mineral density (BMD) in 22 male subjects with complete lesion paraplegia sustained 1.8 to 27 years previously was measured. The measurements were used in screening each subject for a research programme investigating the restoration of standing using functional electrical stimulation (FES). OBJECTIVES: To assess the extent of bone loss in this group of subjects and correlation to age, time post-injury and level of lesion. SETTING: District General Hospital in the UK. METHODS: BMD was measured by dual energy X-ray absorptiometry (DEXA) in the lumbar spine and femoral neck and expressed as an indirect index to an age matched 'normal' population. Fracture risk was described from this score using published data indicating that the risk increased with each standard deviation difference from the 'normal' mean. RESULTS: The bone density in the lumbar spine was better preserved than in the femoral neck. BMD in the lumbar spine was found to be greater than the mean from the age matched population in 57.1% of subjects. Bone loss at the femoral neck suggested that 81.8% of the subjects were at increased risk of fracture, but only 22.7% were at a high risk. No correlation was found between BMD at the lumbar spine or the femoral neck and age, lesion level or time post-injury. CONCLUSION: The study indicates that further investigation into baseline BMD values for the SCI population is required to improve information provided to patients and assessment of fracture risk on an individual basis.

Underestimation of mortality following lung volume reduction surgery resulting from incomplete follow-up.

STUDY OBJECTIVES: Incomplete follow-up can bias interpretation of data that are collected in longitudinal studies. We noted that many patients failed to return for follow-up in a study of effect of lung volume reduction surgery (LVRS) on quality of life (QOL). Accordingly, we designed this investigation to determine the reasons patients dropped out, and to assess differences between those who continued in the study (attendees) and those who did not (nonattendees). DESIGN: Telephone survey. SUBJECTS: Patients with advanced emphysema who had undergone LVRS and had previously agreed to participate in a longitudinal QOL study. RESULTS: No differences were found with regard to age, gender, preoperative pulmonary function, or oxygen use between attendees and nonattendees. Long-term mortality in nonattendees (27%) was considerably greater than that seen in attendees (3%, p < 0.05). Distance from the hospital, financial burden, and living out of the region were the most common reasons cited by surviving nonattendees for their failure to return for follow-up. CONCLUSIONS: Studies reporting the long-term mortality after LVRS can be biased in the direction of underestimating the true value if they are compromised by incomplete follow-up.

Economic analysis of lung volume reduction surgery as part of the National Emphysema Treatment Trial. NETT Research Group.

BACKGROUND: In today's cost-conscious health care environment, obtaining timely and accurate economic information regarding new medical technologies has become extremely important. The National Emphysema Treatment Trial, a multicenter, randomized controlled trial of lung volume reduction surgery (LVRS) plus medical therapy, versus medical therapy for patients with severe emphysema, includes a parallel cost-effectiveness analysis. METHODS: The analysis is designed to determine the cost-effectiveness of LVRS versus medical therapy for those who are eligible for the procedure. After describing theoretical foundations of cost-effectiveness analysis as they apply to this study, we describe the economic and quality of life data that are being collected alongside the clinical trial, methods of analysis, and approach to presenting the results. RESULTS: The cost-effectiveness of LVRS relative to medical therapy will be presented as costs per quality-adjusted life years gained. CONCLUSIONS: This analysis will provide timely economic data that can be considered alongside the clinical results of the National Emphysema Treatment Trial. As one of the largest clinical trials to include a parallel, prospective cost-effectiveness analyses, this study will also provide valuable practical information about conducting an economic analysis alongside a multicenter clinical trial.

Bronchoscopic preparation for airway resection.

In patients being considered for tracheobronchial resection and reconstruction, therapeutic bronchoscopy provides a necessary and complementary role to airway resection. Surgeons involved in tracheobronchial reconstruction need to be adept at airway interventions with the flexible and the rigid bronchoscopes. Bronchoscopy is an important part of the evaluation, stabilization, and preparation of the airway before tracheobronchial resection. Therapeutic bronchoscopy also provides the most common alternative to airway resection so that familiarity with the techniques of therapeutic bronchoscopy is important as the surgeon considers the advantages of definitive versus palliative airway management. Furthermore, postoperative complications of tracheobronchial surgery may require therapeutic endoscopic interventions to optimize outcomes after tracheobronchial resection and reconstruction. In patients being considered for airway resection, bronchoscopy provides the most direct assessment for a tissue diagnosis and measurement of the extent of the lesion and its relation to airway landmarks and an assessment of the quality of the airway being considered for anastomosis. Patients who have critical airway stenosis and impending obstruction can be temporized by bronchoscopic dilatation or core out of endoluminal tumor. Bronchoscopic dilatation or core out allows stabilization of the patient, completion of the assessment for surgical resectability, and performance of an elective rather than an emergent surgical resection. By relieving airway obstruction, therapeutic bronchoscopy also can improve the assessment of tumor margins and allow for clearing of an obstructive pneumonia so that postoperative pulmonary and anastomotic complications are minimized. Airway resection remains the preferred definitive approach for benign and malignant airway pathologies, but therapeutic bronchoscopy provides a useful adjunct to surgery in assessing the patient for surgical resection, preparing the patient for surgery, and optimizing postoperative results.

Airway stenting.

Various airway pathologies may result in central airway obstruction. For patients who have benign and malignant disease, definitive surgical correction by tracheobronchial resection and reconstruction is preferred. Numerous patients, however, have unresectable airway lesions owing to the extent of disease or to medical or surgical contraindications. These patients can be palliated by several endoscopic strategies, including dilatation, core out of tumor, laser resection, endobronchial brachytherapy, or photodynamic therapy. Airway stenting with silicone or expandable metal stents provides reliable and durable palliation in 80% to 95% of properly selected patients. The major advantages of silicone stents are the ease of customization, repositioning, and removal, with the major drawbacks being stent migration or stent obstruction. Expandable metal stents have the advantage of ease of insertion, conformation to the airway, low inner-to-outer diameter ratio, and stent stability. These advantages, however, are offset by (1) the development of tumor ingrowth or of granulation at the end of the stent or through the interstices of the stent and (2) the difficulty or impossibility of stent repositioning or removal once it has been seated completely within the airway. Management of the patient who has central airway obstruction requires a thorough knowledge and consideration of the surgical and endoscopic management options and, usually, a multidisciplinary approach, with experienced thoracic surgical consultation to evaluate the potential for definitive surgical correction. The interventional bronchoscopist must consider the spectrum of endoscopic therapeutics fully. Most patients benefit from combining strategies in a flexible algorithm directed at optimizing patient outcomes. The benefits and risks of airway stenting must be considered in comparison with the other options for airway palliation. In refractory strictures, rapidly recurrent tumor, or extrinsic compression, endobronchial stenting likely will be necessary to achieve durable palliation of airway obstruction. The short- and long-term implications of airway stenting, including the complications of silicone versus expandable metal stents, should be considered thoroughly, while the physician bases treatment or procedure decisions on individual patient anatomy and expected natural history.

FES cycling may promote recovery of leg function after incomplete spinal cord injury.

STUDY DESIGN: Single subject pilot. OBJECTIVES: (i) To see whether strength and endurance for recreational cycling by functional electrical stimulation (FES) are possible following spinal cord injury (SCI). (ii) To develop the equipment for FES-cycling. SETTING: England. METHODS: Near-isometric or cycling exercise was performed by the incomplete SCI subject at home. RESULTS: After training for an average of 21 min per day for 16 months, the stimulated muscles increased in size and the subject was able to cycle for 12 km on the level. Surprisingly, there was a substantial increase in the measured voluntary strength of the knee extensors and the subject reports improved leg function. CONCLUSION: FES-cycling may promote recovery after incomplete spinal cord injury. If so, it offers the possibility of being a convenient method for widespread use.