SEARCH · PubMed Health

Results for “COMPRESSION”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 991 records · Page 55Linked to original sources

PubMed1996

[Dynamic in vivo measurements of local pressure of compression stockings with a microprobe].

Conservative treatment of chronic venous incompetence is based on compression therapy, Carried out correctly, compression therapy improves the venous return from the legs, and also relieves cutaneous congestion. These positive haemodynamic effects are, however, only obtained when the pressure exerted by the compression stocking remains within the desired therapeutic range, not only at rest, i.e. while the patient is seated or reclining, but also during exertion while the patient is standing or walking, furthermore, the pressure exerted must decrease continuously from the tips of the toes to the trunk. Using the dynamic pressure monitoring system described here, the pressure exerted by the compression stocking can be measured continuously between the stocking and the skin at any desired site. The main component of the new microprocessor-based system is a microtip probe for measuring piezoresistance. The probe has an integrated signal filter and is connected to peripheral equipment which records the measured data. The technical design of the system makes it possible accurately to record dynamic measurements of the pressure exerted by compression materials in vivo. This measuring system represents a major step forward in understanding the dynamics of compression during locomotion in vivo, and towards optimizing modern compression therapy.

Bandages↗

PubMed1995

Objectification of compression therapy haemodynamic effect by means of light reflex rheography.

Light reflex rheography (LRR) is one of the non-invasive diagnostic methods which makes it possible to examine venous haemodynamics. Through the use of this method we wanted to prove the positive influence of compression therapy on varices of the lower extremities in the 2nd degree chronic insufficiency. In all, 32 patients were examined (39 extremities), and evaluations were done on them of the initial venous refilling time-Ti, i.e. a segment of the LRR curve during the first three seconds after the cessation of muscle work (12 dorsal flexions sitting). Measurements were made without stockings and with the use of the 2nd compression class stockings made by Loana and with the use of Cambren the 1st compression class stockings. With the 1st compression class stockings, measurements were made with one and two stockings simultaneously. The arithmetic mean of the values measured in the individual groups was evaluated by Student's t-test. Our results confirmed the anticipated prolongation of the initial time (Ti) segment in the monitored patients, even when the 1st class Cambren C stockings were used. Especially when two of these stockings were used simultaneously, the Ti period was fully comparable to the Ti values when the 2nd class compression stockings were used. It has been demonstrated that when two lower compression class stockings are used simultaneously, there is a significantly increased compression effect and an improvement of the function parameters, even in patients with varices and the 2nd degree chronic venous insufficiency.

Adult↗

PubMedDate not supplied

[Characteristics of the process of brain stem compression in the acute period of cranio-cerebral injury].

Proceeding from an analysis of 520 cases of surgery for acute and subacute intracranial haematomas, the author concludes that the process of brain compression is characterized by the tempo, degree and duration that are interrelated. A slow tempo of compression may bring about a significant degree and duration of the compression, with the compression-dislocation syndrome being rather indistinct, which is not observed in cases of a fast tempo. The degree of compression is determined not only by the size of the haematoma, but also by the severity of the contusion and oedema of the brain, by the size of the reserve intracranial spaces, etc. The duration of an acutely developing significant brain compression is a decisive factor in the success of a surgical management of a haematoma. The severity of brain contusion affects various aspects of the compression process--its tempo, degree, and --indirectly--duration.

Adult↗

PubMed1997

Elastic compression stockings: durability of pressure in daily practice.

BACKGROUND: Elastic compression stockings are valuable tools in the treatment of many phlebological diseases. As to day no data are available about how long these elastic compression stockings continue to exert enough compression for a proper clinical function. PATIENTS AND METHODS: In this study we measured the pressure at the B level of compression class II and III elastic stockings directly after the patients started to use them, after 1 month, and after 3 months. In total 99 below knee stocking were measured with a TNO-tester, which has officially been accepted by the CEN for measurement of elastic compression stockings. RESULTS: Class II flat knitted stockings showed a mean pressure of 29.3 (SD 4.9) mmHg at the start of the study, declining to 27.6 (SD 5.2) mmHg, and 26.5 (SD 4.4) mmHg, at 1 and 3 months respectively. The round knitted class II had comparable results. In class III flat knitted stockings we measured 47.5 mmHg (SD 8.1) at the start, and 44.2 (SD 7.1) mmHg, and 41.3 (SD 6.7) mmHg, at 1 and 3 months respectively. Extrapolation of the results after 1 and 3 months demonstrate that the mean pressure of class II stocking is less than 25 mmHg after 4 to 5 months. Class III stockings were less than 35 mmHg close to 6 months, if evaluated in the same way. Individual regression analysis show that after 6 months 66% of the pressure class II stockings have a pressure of less than 25 mmHg and 45% of the pressure class III less than 35 mmHg. When considering a 10% safety margin the figures are respectively 84% and 63%. CONCLUSIONS: From the results of this study it can be concluded that, especially for the most frequently used compression class II stockings, three new stockings each year are necessary to ensure an effective function of the stocking during the time they are being used by the patient. For compression class III flat knitted stockings two pairs can be considered as sufficient.

Aged↗

PubMed1998

Biomechanical assessment of compression screws.

A series of mechanical tests on anatomic specimen cancellous bone and cancellous bonelike foam were conducted to evaluate and compare an Acutrak compression screw with an AO 4-mm cancellous screw and the Herbert screw. The Acutrak and AO screws produced similar fragment compression in foam and bone; Acutrak and AO compression were significantly greater than that of the Herbert screw. However, Acutrak was able to maintain compression after cyclic loading significantly better than were the AO and Herbert screws. The pushout force of Acutrak and AO screws were significantly greater than that of the Herbert screw in foam and bone. The torque required to break fragment contact was significantly greater for the Acutrak than for the AO or Herbert screws, but that for the AO was greater than that for the Herbert screw. The results of this analysis show the Acutrak screw is capable of producing and maintaining compression between bone fracture fragments. In addition, the Acutrak screw was shown to have superior mechanical characteristics than did Herbert screw in every mode tested. The Acutrak screw did not surpass the fragment compression achieved by the AO screw in foam, but it did not overtighten or experience degradation of compression after 500 cycles of simulated physiologic loading.

Biomechanical Phenomena↗

PubMed1983

Suspected epidural compression of the spinal cord and cauda equina by metastatic carcinoma. Clinical diagnosis and survival.

Data from 133 patients with cancer and suspected compression of the spinal cord or cauda equina was reviewed. Although there were differences in presenting symptoms and signs between the group of 62 patients with compression and the 71 without, no single symptom or sign discriminated adequately between the two groups. Multiple logistic regression was used to try to develop an index of signs and symptoms which could identify those without compression, thereby sparing them a myelogram. Eight characteristics, in combination, proved most effective as an index, but they were not perfect predictors of patients with block. Final diagnoses in the group without compression were: vertebral metastases 35%, carcinomatous meningitis 24%, plexopathy and/or neuropathy 21%, other 30% (10% had two diagnoses). Sixty-six percent of those with compression and 50% of those without compression died within six months, although patients rarely survived for much longer.

Adolescent↗

PubMed1995

Hodgkin's disease with spinal cord compression. A case report and a review of the literature.

BACKGROUND: Spinal cord compression is a rare complication of Hodgkin's disease, occurring in only 5% of cases, usually in the setting of progressive, advanced disease. As the initial symptom of Hodgkin's disease, it is extremely rare, with only a few cases reported in the literature. METHODS: A case report of a 46-year-old man who presented with signs and symptoms of spinal cord compression and was found to have an extradural mass in the cervical and thoracic spine is described. Biopsy revealed Hodgkin's disease. This case report represents a unique case of a patient with Hodgkin's disease presenting with epidural disease, with spinal cord compression as the only apparent site of initial clinical involvement. A review of the literature of patients with Hodgkin's disease presenting with spinal cord compression from 1970 to the present is presented. RESULTS: The patient, whom we report, received chemotherapy followed by external beam radiation therapy and achieved complete resolution of symptoms and a complete response by radiologic criteria. Based on a review of the literature, Hodgkin's disease involving the spinal epidural space is very responsive to radiation therapy and chemotherapy with a good prognosis for both functional recovery (86%), complete response (61%), and long term survival. CONCLUSIONS: Chemotherapy and/or radiation therapy is successful treatment for Hodgkin's disease presenting with spinal cord compression. For the rare patient who presents with spinal cord compression as the initial symptom of Hodgkin's disease, the therapeutic options include chemotherapy alone, radiation therapy alone, or combined modality therapy.

Hodgkin Disease↗

PubMed1989

Structural assessment of rat sciatic nerve following tourniquet compression and vascular manipulation.

In a recent study (Nitz et al., Exp Neurol 94:264-279, 1986) the validity of a rat animal model to examine effects of tourniquet compression and vascular occlusion on limb motor function, leg girth, and electrophysiologic changes was established. Here we report observations on sciatic nerve morphologic and morphometric alterations of these same animals. The hindlimbs of 90 rats were compressed by a pneumatic tourniquet at clinically relevant pressures (200 to 400 mm Hg) for 1 to 3 hours, and the sciatic nerve was assessed by light and electron microscopy at 1, 3, and 6 weeks post compression. The nerves were also examined from five additional animals at each of these time intervals following arterial ligation and sciatic nerve epineurectomy (30 rats). Percentage of degenerating myelinated nerve fibers and volume fraction of mast cells and fibroblasts were quantified morphometrically. The percentage of degenerating myelinated nerve fibers after moderate to severe tourniquet compression and vascular manipulation was similar and ranged from 15% to 45%. Tourniquet compression, but not vascular occlusion, resulted in an increase of mast cells and fibroblasts and disruption of endothelial cells of endoneurial vessels. The results suggest that clinically relevant tourniquet compression causes a secondary increase in vascular permeability, intraneural edema, and subsequent prolonged tissue ischemia, resulting in nerve degeneration.

Animals↗

PubMed2006

Compression of fluorescence microscopy images based on the signal-to-noise estimation.

Modern microscopic techniques like high-content screening (HCS), high-throughput screening, 4D imaging, and multispectral imaging may involve collection of thousands of images per experiment. Efficient image-compression techniques are indispensable to manage these vast amounts of data. This goal is frequently achieved using lossy compression algorithms such as JPEG and JPEG2000. However, these algorithms are optimized to preserve visual quality but not necessarily the integrity of the scientific data, which are often analyzed in an automated manner. Here, we propose three observer-independent compression algorithms, designed to preserve information contained in the images. These algorithms were constructed using signal-to-noise ratio (SNR) computed from a single image as a quality measure to establish which image components may be discarded. The compression efficiency was measured as a function of image brightness and SNR. The alterations introduced by compression in biological images were estimated using brightness histograms (earth's mover distance (EMD) algorithm) and textures (Haralick parameters). Furthermore, a microscope test pattern was used to assess the effect of compression on the effective resolution of microscope images.

Algorithms↗

PubMed1989

Effects of experimental graded compression on blood flow in spinal nerve roots. A vital microscopic study on the porcine cauda equina.

Compression injuries of spinal nerve roots are very common. However, the basic pathophysiology of these conditions is not fully understood. In this study a model is presented for experimental graded compression of the nerve roots of the pig cauda equina, including a technique for vital microscopic studies on the microcirculation flow of the intrinsic vessels of the nerve roots during compression. With this model critical pressure levels for compression-induced occlusion of the arterioles, capillaries, and venules of the intrinsic vasculature of the nerve roots were determined. The study showed that the average minimum pressure in the inflated balloon required to stop the flow in the arterioles was 127 mm Hg (SD = 18, n = 11), in the capillaries 40 mm Hg (SD = 6, n = 12), and in the venules 30 mm Hg (SD = 10, n = 12). The average mean arterial pressure (MAP) was 150 mm Hg (SD = 14, n = 12). There was a statistically significant correlation (p greater than 0.001) between the MAP and the pressure required to stop the flow in the arterioles (r = 0.83, n = 14), but no correlation between MAP and capillary (r = 0.09 NS, n = 20) or venular (r = -0.28 NS, n = 34) occlusion pressure. After the nerve roots had been compressed at 50 or 200 mm Hg for 10 min or 2 h, the recirculation started immediately. There was a hyperemia during the first 10 min, with a dilatation of the vessels, particularly the venules. In nerve roots exposed to compression for 2 h at either 50 or 200 mm Hg, an intraneural edema developed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1998

Effect of static compression on proteoglycan biosynthesis by chondrocytes transplanted to articular cartilage in vitro.

Transplantation of chondrocytes by injection or within carrier matrices has shown promise for augmenting the repair of articular cartilage defects. In vivo, transplanted chondrocytes are exposed to mechanical forces. This in vitro study examined the effect of a step application of compressive load to chondrocytes after the cells had been seeded onto a cartilage surface. Bovine chondrocytes were transplanted onto bovine cartilage disks, allowed to attach for 1 hour or 4 days, and subjected to compression through overlying cartilage disks in a confined compression configuration. Before use, the disks were lyophilized to lyse the endogenous chondrocytes and thereby allow assessment of the metabolic activity of the transplanted cells. During a 16-hour application of compressive stress of 0.24-0.72 MPa, proteoglycan synthesis, assessed as [35S]sulfate incorporation into macromolecules, was inhibited by approximately 68% after the 1-hour attachment and by approximately 45% after the 4-day attachment. Cell retention after the application of load was assessed by use of [3H]thymidine-tagged chondrocytes and quantitation of the displacement of radioactivity. After the 1-hour seeding period, loading induced a dose-dependent dislodgment of [3H]radioactivity (as much as 35%) from the tissue bilayer. In contrast, after the 4-day seeding period, there was no detectable effect of loading on chondrocyte dislodgment with an 8-12% release of radioactivity. The inhibitory effect of a 16-hour compression of 0.48 MPa applied after the 4-day seeding period was studied further. This protocol did not appear to have an irreversible effect on chondrocyte metabolism; at 2 days after the release of load, proteoglycan synthesis by the loaded cells was stimulated by 41% compared with transplanted cells that were not subjected to loading. These results suggest that the application of static compressive stress to chondrocytes at a cartilage surface may affect biosynthesis by these cells and thus subsequent integrative cartilage repair. Such an effect may have implications for optimization of the tightness of the press fit of a cell-laden cartilaginous construct into an articular defect.

Animals↗

PubMed1987

Treatment with an aldose reductase inhibitor can reduce the susceptibility of fast axonal transport following nerve compression in the streptozotocin-diabetic rat.

The effect of treatment with an aldose reductase inhibitor on the susceptibility of peripheral nerves to compression was studied in rats made diabetic by the injection of streptozotocin (50 mg.kg-1). The response to nerve compression was determined in untreated diabetic rats after 22 days of diabetes and compared with the response in two similar groups of diabetic rats which had been treated with the aldose reductase inhibitor 'Statil' (ICI 128436; 25 mg.kg-1.day-1 orally) either from the induction of diabetes or for 7 days prior to nerve compression. Two groups of non-diabetic rats were treated with 'Statil' for either 22 days or 7 days to act as controls. Inhibition of fast axonally transported proteins was induced by local compression of the sciatic nerves 4 h after application of 3H-leucine to the motor neurone cell bodies in the spinal cord. The inhibition of fast axonal transport was quantified by calculation of a transport block ratio. Compression at 30 mmHg for 3 h induced a significantly greater (p less than 0.05) inhibition of axonal transport at the site of compression in nerves of untreated diabetic rats (transport block ratio 0.96 +/- 0.24, n = 8) than in nerves of control rats treated with the aldose reductase inhibitor for either the shorter time of 7 days (0.71 +/- 0.17, n = 10) or the longer time of 22 days (0.69 +/- 0.08, n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗

PubMed1998

The effect of duration of compression on lipid peroxidation after experimental spinal cord injury.

The present study was performed to evaluate the effect of duration of acute spinal cord compression on tissue lipid peroxidation in rats. A clip compression method (1) was used to produce acute spinal cord injury. Rats were divided into 3 groups, each consisting of 10. At 1 hour after trauma all rats were sacrificed, and MDA content of the injured spinal cord segment was measured. The tissue MDA contents were 3.922 mumolMDA/gww in group 1 (control), 10.192 mumol MDA/gww in group 2 (30 seconds compression), and 12.147 mumolMDA/gww in group 3 (60 seconds compression). These results demonstrate that the length of duration of compression significantly enhances lipid peroxidation. Our study supported the view that persisting compression may cause progression of secondary mechanisms which may irreversibly eliminate any potential for recovery.

Animals↗

PubMed2001

[Comparative biomechanical compression trials with a new vertebral prosthetic implant].

UNLABELLED: The authors present a new titanium implant for replacement of the vertebral body (Synex). Possible indications would be fractures or dislocations with destruction of the anterior column, posttraumatic kyphosis as well as tumors in the throracolumbar spine. The construction has to be completed by a stabilizing implant. For best fit and contact to adjacent end-plates Synex is distractable in situ. The possibility of secondary dislocation or loss of correction should thereby be minimised. OBJECTIVES: We performed comparative compression tests with Synex and MOSS ("Harms mesh cage") on human cadaveric specimens of intact vertebrae (L1). The aim of the study was to measure the compressive strength of the vertebral body end-plate in uniaxial loading via both implants to exclude a caving of Synex in vivo. METHODS: 12 human cadaveric specimens of intact vertebrae (L1) were divided in 2 similar groups (matched pairs) according to bone mineral density (BMD), determined using DE-QCT. The specimens were loaded with axial compression force at a constant speed of 5 mm/min to failure and the displacement was recorded with a continuous load-displacement curve. RESULTS: The mean ultimate compression force (Fmax) showed a tendency towards a higher result testing Synex with 3396 N versus 2719 N (non significant). The displacement until Fmax was 2.9 mm in group S (Synex), which was half as long as in group M (5.8 mm). The difference was significant (p < 0.001). The compression force was twice as high and significantly (p < 0.05) higher with Synex at a displacement of 1 mm, 1.5 mm and 2 mm. A significant (p < 0.001) correlation (R = 0.89) between Fmax and BMD was found. CONCLUSIONS: Synex was found to be at least comparable to MOSS for suspensory replacement of the vertebral body at the thoracolumbar spine. A possible consequence of the significantly higher mean compression forces between 1 and 2 mm displacement might be a decreased segmental deformation or loss of correction.

Adult↗

PubMed2000

Imaging of compressive vertebral haemangiomas.

Compressive vertebral haemangiomas (VHs) are rare. Correct preoperative diagnosis is useful both for operative planning (since compressive VHs are extremely vascular lesions) and to allow preoperative embolisation. Numerous radiological signs for VHs have been described, but compressive VHs frequently have atypical features. In particular, magnetic resonance features are not well established. We present imaging features in three cases of compressive VH and review the imaging findings in an additional 106 previously published cases. Findings were typical in 52 of 80 plain film (65%), 33 of 41 computed tomography (80%) and 13 of 25 magnetic resonance examinations (52%). The prevalence of previously described imaging features is reported. Awareness of the range of magnetic resonance features is important since this is frequently the initial investigation in patients presenting with symptoms of neural compression. Since computed tomography is typical in 80% of cases, this is a useful confirmatory test if magnetic resonance features are suspicious but not diagnostic of compressive VH.

Adolescent↗

PubMed1999

Apoptosis of oligodendrocytes occurs for long distances away from the primary injury after compression trauma to rat spinal cord.

We evaluated by in situ nick end labeling the presence of apoptotic glial cells in the spinal cord of rats which have sustained a moderate and severe compression injury at the level of T8-9, resulting in a severe but reversible paraparesis and irreversible paraplegia, respectively. In a previous investigation we found apoptotic glial cells (oligodendrocytes) in the immediate vicinity of the primary lesion (T7 and T10). The present study was designed to evaluate the extent of such cells in the spinal cord even at long distances away from the primary injury. Rats sustaining a moderate and severe compression injury and surviving 4 and 9 days showed a significant increase in the number of apoptotic glial cells at the T1, T5, T7, T12 and L2 levels. At the T10 level the elevation was significant only after day 9. There was no significant increase in the number of these cells at 4 h and 1 day after moderate and severe compression. In general, the apoptotic cells were most often seen in segments adjacent to the compression. They were randomly located in the ventral, lateral and dorsal tracts but were rarely present in the gray matter of the cord. In conclusion, compression trauma to rat spinal cord induces signs of apoptosis in glial cells, presumably oligodendrocytes of the long tracts. This newly discovered type of secondary injury is widely distributed in the damaged spinal cord and occurs even at long distances remote from the initial compression injury. Apoptotic cell death of oligodendrocytes will induce myelin degeneration and cause additional disturbances of axonal function. This cell damage may be a target for future therapy since it occurs after a delay and chemical compounds are now available by which apoptotic cell death can be modified.

Amyloid beta-Protein Precursor↗

PubMed2000

Spinal cord compression injury in the mouse: presentation of a model including assessment of motor dysfunction.

The purpose of this study was to develop a spinal cord injury model in the mouse. Various degrees of extradural compression were used to induce mild, moderate or severe compression injuries. Furthermore, a locomotor rating scale was developed by which the functional outcome of the spinal cord injury could be assessed. The introduction of such a model will be useful for further studies on the pathogenesis and treatment strategies of spinal cord injury. To assess hindlimb motor function, a 10-point scale was used. Initially, the animals were allowed to move freely in an open field and were rated 0-5, 0 being no movement and 5 being almost normal. Animals scoring a 5 were then assessed using steel bars with decreasing widths from 2 cm to 5 mm. For each bar successfully crossed over, they gained additional points. Before injury the hindlimb motor function score (MFS) in all the animals was 10. In mice with mild compression, MFS was decreased slightly on day 1 and recovered to 9 +/- 0.6 on day 14. For mice with moderate compression, the MFS decreased to 4.6 +/- 0.4 on day 1 after injury and gradually improved to 8.1 +/- 0.6 on day 14. Severe injury resulted in paraplegia of the hindlimbs day 1 after injury with a score of 0.6 +/- 0.2. By day 14 after injury, these animals gradually recovered to 3.9 +/- 0.1, could bear the weight on the hindlimbs and walk with a severe deficit. There was a 3%, 9% and 19% decrease in the total cross-sectional area of the spinal cord 14 days after mild, moderate and severe injury, respectively. Microtubule-associated protein immunostaining revealed that the gray matter decreased to 61 +/- 7% in moderately injured animals, while severe compression resulted in a complete loss of gray matter. White matter decreased to 86 +/- 6% in moderately injured animals and 29 +/- 11% in severely injured animals. This study shows that the mouse can be used to achieve reproducible spinal cord compression injuries of various degrees of severity. The force of the impact correlates well with the neurological and light microscopic outcome. The motor function test presented in this paper and the computerized quantification of tissue damage can be used to evaluate the efficacy of different treatment strategies.

Animals↗

PubMed2006

Analysis of the relationship between peak stress and proteoglycan loss following injurious compression of human post-mortem knee and ankle cartilage.

While traumatic joint injuries are known to increase the risk of osteoarthritis (OA), the mechanism is not known. Models for injurious compression of cartilage may identify predictors of injury that suggest a clinical mechanism. We investigated the relationship between peak stress during compression and glycosaminoglycan (GAG) loss after injury for knee and ankle cartilages. Human cartilage explant disks were harvested post-mortem from the knee and ankle of three organ donors with no history of OA and subjected to injurious compression to 65% strain in uniaxial unconfined compression at 2 mm/s (400%/s). The GAG content of the conditioned medium was measured 3 days after injury. After injury of knee cartilage disks, damage was visible in 18 of 39 disks (36%). Three days after injury, the increase in GAG loss to the medium (GAG loss from injured disks minus GAG loss from location-matched uncompressed controls) was 1.5+/-0.3 microg/disk (mean +/- SEM). With final strain and compression velocity held constant, we observed that increasing peak stress during injury was associated with less GAG loss after injury (P<0.001). In contrast, ankle cartilage appeared damaged after injury in only 1 of 16 disks (6%), there was no increase in GAG loss (0.0+/-0.3 microg/disk), and no relationship between peak stress and increase in GAG loss was detected (P=0.51). By itself, increasing peak stress did not appear to be an important cause of GAG loss from human cartilage in our injurious compression model. However, we observed further evidence for differences in the response of knee and ankle cartilages to injury.

Ankle↗