PubMed Health⌕ Search

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 127 records · Page 7Linked to original sources
PubMed1994

A simple data compression scheme for binary images of bacteria compared with commonly used image data compression schemes.

A run length code compression scheme of extreme simplicity, used for image storage in an automated bacterial morphometry system, is compared with more common compression schemes, such as are used in the tag image file format. These schemes are Lempel-Ziv and Welch (LZW), Macintosh Packbits, and CCITT Group 3 Facsimile 1-dimensional modified Huffman run length code. In a set of 25 images consisting of full microscopic fields of view of bacterial slides, the method gave a 10.3-fold compression: 1.074 times better than LZW. In a second set of images of single areas of interest within each field of view, compression ratios of over 600 were obtained, 12.8 times that of LZW. The drawback of the system is its bad worst case performance. The method could be used in any application requiring storage of binary images of relatively small objects with fairly large spaces in between.

Bacteria↗
PubMed2003

Randomized, pilot study of intermittent pneumatic compression devices plus dalteparin versus intermittent pneumatic compression devices plus heparin for prevention of venous thromboembolism in patients undergoing craniotomy.

BACKGROUND: Unfractionated heparin and the low molecular weight heparin, dalteparin, are used for prophylaxis against venous thromboembolism in patients undergoing craniotomy. These drugs were compared in a randomized, prospective pilot study comparing intermittent pneumatic compression devices plus dalteparin to intermittent pneumatic compression devices plus heparin. METHODS: One hundred patients undergoing craniotomy were randomly allocated to receive perioperative prophylaxis with subcutaneous (SC heparin, 5000 units every 12 hours, or dalteparin, 2,500 units once a day, begun at induction of anesthesia and continued for 7 days or until the patient was ambulating. Entry criteria were age over 18 years, no deep vein thrombosis (DVT) preoperatively as judged by lower limb duplex ultrasound and no clinical evidence of pulmonary embolism preoperatively. Patients with hypersensitivity to heparin, penetrating head injury or who refused informed consent were excluded. Patients underwent a duplex study 1 week after surgery and 1 month clinical follow-up. All patients were treated with lower limb intermittent pneumatic compression devices. RESULTS: There were no differences between groups in age, gender, and risk factors for venous thromboembolism. There were no differences between groups in intraoperative blood loss, transfusion requirements or postoperative platelet counts. Two patients receiving dalteparin developed DVT (one symptomatic and one asymptomatic). No patient treated with heparin developed DVT and no patient in either group developed pulmonary embolism. There were two hemorrhages that did not require repeat craniotomy in patients receiving dalteparin and one that did require surgical evacuation in a patient treated with heparin. Drug was stopped in two patients treated with dalteparin because of thrombocytopenia. None of these differences were statistically significant. CONCLUSION: There was no significant difference in postoperative hemorrhage, venous thromboembolism or thrombocytopenia between heparin and dalteparin. The results suggest that, given the small sample size of this trial, both drugs appear to be safe and the incidence of venous thromboembolism by postoperative screening duplex ultrasound appears to be low when these agents are used in combination with intermittent pneumatic compression devices.

Adult↗
PubMed2001

About the use of stoichiometric hydroxyapatite in compression - incidence of manufacturing process on compressibility.

Literature concerning calcium phosphates in pharmacy exhibits the chemical diversity of the compounds available. Some excipient manufacturers offer hydroxyapatite as a direct compression excipient, but the chemical analysis of this compound usually shows a variability of the composition: the so-called materials can be hydroxyapatite or other calcium phosphates, uncalcined (i.e. with a low crystallinity) or calcined and well-crystallized hydroxyapatite. This study points out the incidence of the crystallinity of one compound (i.e. hydroxyapatite) on the mechanical properties. Stoichiometric hydroxyapatite is synthesized and compounds differing in their crystallinity, manufacturing process and particle size are manufactured. X-Ray diffraction analysis is used to investigate the chemical nature of the compounds. The mechanical study (study of the compression, diametral compressive strength, Heckel plots) highlights the negative effect of calcination on the mechanical properties. Porosity and specific surface area measurements show the effect of calcination on compaction. Uncalcined materials show bulk and mechanical properties in accordance with their use as direct compression excipients.

Calcium↗
PubMedDate not supplied

[Optimization of the dynamic compression in angle-plated osteosynthesis by static interfragmentary compression--experimental results].

Osteosynthesis with an angled plate after intertrochanteric osteotomy is mainly a tension-band-osteosynthesis. Because of the lack of interfragmentary compression at the medial corticalis this technique may lead to pseudarthrosis or delayed bone union. On the basis of theoretical considerations and extensive experiments, we found a distinct improvement in interfragmentary compression when the osteotomy-planes are set at an angle of 6 degrees open to the lateral side before external compression with 1000 N. In this way "functional plate-prebending" is achieved. Thus tension-band-osteosynthesis is completed by compression osteosynthesis.

Bone Plates↗
PubMed1998

Enoxaparin plus compression stockings compared with compression stockings alone in the prevention of venous thromboembolism after elective neurosurgery.

BACKGROUND: Compression stockings are recommended for prophylaxis against venous thromboembolism in patients undergoing neurosurgery, but anticoagulant agents have not gained wide acceptance because of concern about intracranial bleeding. METHODS: In a multicenter, randomized, double-blind trial, we assessed the efficacy and safety of enoxaparin in conjunction with the use of compression stockings in the prevention of venous thromboembolism in patients undergoing elective neurosurgery. Enoxaparin (40 mg once daily) or placebo was given subcutaneously for not less than seven days beginning within 24 hours after the completion of surgery. The primary end point was symptomatic, objectively confirmed venous thromboembolism or deep-vein thrombosis assessed by bilateral venography, which was performed in all patients on day 8+/-1. Bleeding side effects were carefully assessed. RESULTS: Among the 307 patients assigned to treatment groups, 129 of the 154 patients receiving placebo (84 percent) and 130 of the 153 patients receiving enoxaparin (85 percent) had venographic studies adequate for analysis. An additional patient in the placebo group died before venography of autopsy-confirmed pulmonary embolism. In this analysis, 42 patients given placebo (32 percent) and 22 patients given enoxaparin (17 percent) had deep-vein thrombosis (relative risk in the enoxaparin group, 0.52; 95 percent confidence interval, 0.33 to 0.82; P=0.004). The rates of proximal deep-vein thrombosis were 13 percent in patients receiving placebo and 5 percent in patients receiving enoxaparin (relative risk in the enoxaparin group, 0.41; 95 percent confidence interval, 0.17 to 0.95; P=0.04). Two patients in the placebo group died of autopsy-confirmed pulmonary embolism on days 9 and 16. Major bleeding occurred in four patients receiving placebo (intracranial bleeding in all four) and four patients (intracranial bleeding in three) receiving enoxaparin (3 percent of each group). CONCLUSIONS: Enoxaparin combined with compression stockings is more effective than compression stockings alone for the prevention of venous thromboembolism after elective neurosurgery and does not cause excessive bleeding.

Adult↗
PubMed1973

Mechanics of the Compression Wood Response: II. On the Location, Action, and Distribution of Compression Wood Formation.

A new method for simulation of cross-sectional growth provided detailed information on the location of normal wood and compression wood increments in two tilted white pine (Pinus strobus L.) leaders. These data were combined with data on stiffness, slope, and curvature changes over a 16-week period to make the mechanical analysis. The location of compression wood changed from the under side to a flank side and then to the upper side of the leader as the geotropic stimulus decreased, owing to compression wood action. Its location shifted back to a flank side when the direction of movement of the leader reversed. A model for this action, based on elongation strains, was developed and predicted the observed curvature changes with elongation strains of 0.3 to 0.5%, or a maximal compressive stress of 60 to 300 kilograms per square centimeter. After tilting, new wood formation was distributed so as to maintain consistent strain levels along the leaders in bending under gravitational loads. The computed effective elastic moduli were about the same for the two leaders throughout the season.

Journal Article↗
PubMed2000

Breast biphasic compression versus standard monophasic compression in X-ray mammography.

Breast biphasic compression (22.5 degrees angled paddle, followed by progressive angle reduction) was compared with standard monophasic compression in x-ray mammography. The presence of the pectoral muscle was recorded for the craniocaudal (CC) view and the presence of the inframammary fold for the mediolateral oblique (MLO) view. The amount of breast in each study and image quality were assessed for both views. For all parameters, biphasic compression performed better than monophasic compression in both CC (P: <.006) and MLO (P: <.04) views.

Adult↗
PubMed2004

Efficacy and tolerability of an ulcer compression stocking for therapy of chronic venous ulcer compared with a below-knee compression bandage: results from a prospective, randomized, multicentre trial.

OBJECTIVE: To investigate the possibility of improving healing rates in ulcus cruris venosum by using an ulcer compression stocking (U-Stocking) (Venotrain ulcertec) as compared to compression bandages. RESEARCH DESIGN AND SETTING: Prospective, multicentre, open-labelled, randomized, active-controlled study with blinded assessment of the primary endpoint. Sixteen phlebology outpatient clinics in Germany or the Netherlands or German medical practices specialized in phlebology. PATIENTS AND METHODS: 134 patients with venous leg ulcers entered the study. Among others, patients with infected ulcer or obesity were excluded. 121 patients were eligible for primary efficacy analyses. U-Stocking or bandages applied for at least eight hours per day and for up to 12 weeks. The primary endpoint was the healing rate after 12 weeks as assessed by planimetric measures. The secondary outcome variables were time to healing, changes in ulcer size (planimetry), experience of use and patient compliance. MAIN OUTCOME MEASURES: Therapy with the U-Stocking produced a significantly higher rate of complete healing of 47.5% (29/61) versus 31.7% (19/60) with bandages, 1-sided p = 0.0129 [CI: 95% for differences: 4.3% to 28.5%]. Mean time to healing was 46 days in both groups. Time required for application of the U-Stocking was a mean of 5.4 min (SD 5.4) versus 8.5 min (SD 6.5) for bandages, p = 0.0001. Around three patients in each treatment group were affected by serious adverse events. All treatment-related adverse events are known for compression therapy. CONCLUSIONS: The U-Stocking was superior to bandages in compression therapy for venous ulcer. This is of significance to new treatment standards as well as to future studies of longer term therapy (> 12 weeks) for unhealed ulcers or prevention of recurrence.

Aged↗
PubMed1980

[Compression therapy of the lower extremities particularly with compression stockings].

The compression therapy of the lower extremities is based on strong patho-physiologic lines and is well codified. The necessary values of pression for any case and the exact indication for compression stockings and pantys for each compression class are well known. The physician has to prescribe thoroughly the adequate compression stocking, thus protecting the patient best against further complications.

Arteries↗
PubMedDate not supplied

[A compressed form for presenting data to banks on the primary and spatial structure of biopolymers. Means for accessing compressed data banks].

Description of open CAN format (Compressed Amino acids and Nucleotides) is presented for storing genetic information in compressed form in data banks (DB). Data compression principles are demonstrated in detail on examples of EMBL DB (sequences of nucleotides), SWISSPROT DB (sequences of amino acids) and PDB DB (3D structures). A unified compressed data format provides a possibility to integrate EMBL, SWISSPROT, and PDB DB in one data bank. We are going to use this approach for integration of GENBANK and other similar DBs. One of the outcomes of the research is a library of data retrieval procedures for access to DB, providing developers of the application software packages with a uniform interface to DBs with biologically related data. The proposed scheme for data representation was recommended by the Expert Commission of the Informatics Section of the RSSIP "Human Genome" as a standard for distribution of data banks in Russia.

Amino Acid Sequence↗
PubMed2003

[Compressibility of directly compressed forms of lactitol].

Lactitol ranks among sugar alcohols which are employed as dry binders in the manufacture of tablets, particularly the chewable ones. Water-granulated lactitol is the directly compacting form of this substance. The present paper studies the compressibility of the granulated form of lactitol and the effects of different concentrations of the lubricant magnesium stearate on the strength and disintegration time of the compacts from his substance. Lactitol cannot be compressed without an added lubricant. Magnesium stearate, employed in two concentrations, 0.4% and 0.8%, did not negatively interfere with the strength of the compacts. The disintegration period of tablets was prolonged with increasing stearate concentration, but independently of compression force.

Chemistry, Pharmaceutical↗
PubMed2005

In vitro biomechanical comparison of limited contat dynamic compression plate and locking compression plate.

The locking compression plate (LCP) supports biological osteosynthesis by functioning as an internal fixator, rather than as a full or limited contact bone plate which must be adequately contoured and affixed directly to the bone for stable internal fixation of the fracture. In order to help justify the use of the LCP in our veterinary patients, in vitro biomechanical testing was performed comparing the LCP to the conventional limited contact dynamic compression plate (LC-DCP) in canine femurs. We hypothesized that the LCP construct would be at least as stiff under bending and torsional loads as the LC-DCP. The LCP and LC-DCP were applied over a 20-mm osteotomy gap to contralateroal bones within each pair of 14 femora. Non-destructive four-point bending and torsion, and cyclical testing in torsion were performed. The constructs were then loaded to failure in torsion. In medial-lateral and lateral-medial structural bending, significant differences were not found between the LCP and LC-DCP, however, at the gap, the LCP construct was stiffer than the LC-DCP in lateral-medial bending. Significant differences in behaviour over time were not noted between the plate designs during cyclical testing. When loading the constructs to failure in internal rotation, the LC-DCP failed at a significantly lower twist angle (P = .0024) than the LCP. Based on the similar performance with loading, the locking compression plate is a good alternative implant for unstable diaphyseal femoral fracture repair in dogs.

Animals↗
PubMed1986

Normal vertebral body size and compressive strength: relations to age and to vertebral and iliac trabecular bone compressive strength.

Three thoracic (T5-T7) and three lumbar (L1-L3) vertebral bodies and the anterior parts of both iliac crests were removed from 44 normal individuals aged 15-87 years who had died suddenly. Small, cylindrical samples of trabecular bone (length 5 mm, diameter 7 mm) from T6, L1, and L3 and from the standard site for iliac crest biopsies were compressed in an Alwetron-250 materials testing machine. Whole vertebral bodies from T5, T7, and L2 with cut planoparallel end-plates were compressed in an Instron materials testing machine. The maximum compressive stress value sigma max of the whole vertebral bodies and of the vertical vertebral trabecular bone decreased with age with almost parallel linear regression lines. At any age the sigma max for whole vertebral bodies was about 1.6 MPa (1 MPa = 100 N/cm2) higher than for the trabecular bone. The average cross-sectional area of the vertebral bodies increased by 25-30% from the age of 20 to 80 years. The anisotropic properties of the vertebral trabecular bone (expressed as the ratio between the vertical and horizontal sigma max) increased markedly with age. A highly significant positive correlation was observed between the vertical vertebral trabecular bone sigma max (X) and the total vertebral body sigma max (y = 0.90x + 1.75, r = 0.88, P less than 0.01). The slope was not significantly different from 1, whereas the intercept was positive (P less than 0.01). The average total vertebral body sigma max (range 1.5-7.8 MPa) could be predicted from mechanical tests on horizontal iliac crest bone biopsies with standard error of estimate (SEE) of 0.92 MPa.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2001

Locking Compression Plate (LCP). An osteosynthesis plate based on the Dynamic Compression Plate and the Point Contact Fixator (PC-Fix).

Based on many years of experience with compression plating and promising results obtained with so-called internal fixators, an implant system was developed which combines the two treatment methods in one implant. Despite the combination of these different fracture treatment techniques, no compromises were made with regard to application as a compression plate or as a bridging device in the form of an internal fixator. The individual construction elements in this new implant system have individually proven themselves extremely valuable in clinical practice. The integration of these well proven elements into the new implant system has made it compatible with the majority of existing instruments and conventional screws. The surgeon is free to select the best treatment method to suit the fracture situation and to make combinations as and when necessary. The LCP (Locking Compression Plate), the product of these combinations, is in line with the latest plating techniques, the aim of which is to achieve the smallest possible surgical incisions and to preserve the blood supply to the bone and the adjacent soft tissues.

Bone Plates↗
PubMed2005

The venous return simulator: an effective tool for investigating the effects of external compression on the venous hemodynamics--first results after thigh compression.

BACKGROUND: To present a virtual model, the venous return simulator (VRS), designed to compute venous hemodynamic variations when compression is applied to the leg. METHODS: The VRS defines a numerical network of the lower extremity and computes the dynamic variables (flow rate, venous diameter and internal pressure) for a defined external pressure. The VRS was based on physiological data from the literature and clinical studies on healthy subjects. Clinical correlations were required to confirm its validity; for this purpose, we carried out experiments simulating the conditions of a clinical trial, in which the diameter of superficial and deep veins was measured while increasing pressures (20, 40 and 60 mmHg.) were applied to the thighs of patients enduring deep valvular insufficiency and venous ulcers. The diameters and flow rates calculated using our VRS model were compared with the experimental data obtained at the same thigh compression levels. RESULTS: The numerical results of VRS are in good agreement with the clinical data obtained by Duplex, (R2 = 0.96). In accordance with the in vivo measurement the computed results show that only a pressure greater than 40 mmHg is able to reduce the venous diameter at thigh-level, both in the great saphenous vein and in the femoral vein. CONCLUSION: The venous return simulator computes lower limb hemodynamic parameters under static conditions. The good correlation existing between the VRS and the data obtained in a previous clinical study shows that this numerical approach could provide a useful means of predicting the hemodynamic consequences of compression therapy.

Bandages↗
PubMed2006

SII and fit-to-target analysis of compression system performance as a function of number of compression channels.

This work was undertaken to answer the question, 'How does the speech audibility/fit-to-gain-target provided by compression change with number of channels?' For each of 957 audiograms and a given number of compression channels, the channel crossover frequencies were set either to maximize the SII (speech intelligibility index) for low- and high-level speech spectra, or to optimize the fit-to-gain targets from the Cambridge method for loudness equalization (CAMEQ). The audiograms comprised all common configurations, and losses ranged from mild to severe. Use of these computational procedures allowed the predicted, channel-number-based performance to be determined separately from the effects of other compression parameters. From one to five channels were sufficient to yield predicted speech recognition performance within 5% of maximum for 90% of the 'mild' and 'moderate' audiograms. Three to nine channels were necessary for the same level of predicted performance for 90% of the 'severe' audiograms. Four channels or fewer were sufficient to produce less than 5 dB rms error in fit to CAMEQ targets for 90% of all audiograms.

Hearing Aids↗
PubMed2004

Comparative evaluation of the powder properties and compression behaviour of a new cellulose-based direct compression excipient and Avicel PH-102.

This study compares the compression behaviour of a new cellulose-based tableting excipient, hereinafter referred to as UICEL-A/102, and Avicel PH-102, a commercial direct compression excipient commonly referred to as microcrystalline cellulose (MCC). UICEL-A/102 shows the cellulose II lattice, while Avicel PH-102 belongs to the cellulose I polymorphic form. The median particle diameters of UICEL-A/102 and Avicel PH-102 fractions used in the study were 107 and 97 microm, respectively. Compared with Avicel PH-102, UICEL-A/102 was more dense; the relative poured and tapped densities were: 0.277 and 0.327 (vs 0.195 and 0.248 for Avicel PH-102), respectively. The true density, rhotrue, of the two materials was comparable ( approximately 1.56 g cm(-3)). The slopes of the in-die and out-of-die Heckel curves for Avicel PH-102 were steeper than for UICEL-A/102. The relative density versus applied pressure plot was in good agreement with the modified Heckel equation. The out-of-die and in-die minimal pressure susceptibility (chipmin) values calculated were 3.36 x 10(-3) and 8.09 x 10(-3) MPa(-1) for UICEL-A/102 and 8.00 x 10(-3) and 16.12 x 10(-3) MPa(-1) for Avicel PH-102, respectively. The elastic recovery profiles showed UICEL-A/102 to be more elastic than Avicel PH-102. In conclusion, UICEL-A/102 and Avicel PH-102 differ in their compression behaviour under pressure. The different polymorphic forms could provide a possible explanation.

Cellulose↗