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PubMed1989

A mechanical assessment of applied compression and healing in knee arthrodesis.

The applied compression and stiffness of a knee arthrodesis treated with unilateral external fixation can be mechanically assessed. Of ten patients in whom arthrodesis bending stiffness measurements were obtained during healing, nine had a minimum bending stiffness of 5 Nm/degree and sound clinical fusion. In seven of these nine patients, a bending stiffness of at least 10 Nm/degree was obtained, suggesting that this stiffness value is a safe and reliable indicator for successful arthrodesis. Arthrodesis compression declined rapidly; daily adjustments were required to maintain a compression of 500 Newtons. A small but significant loss of length was associated with this high value of compression. On reduction of the compression to 200 Newtons, the rate of decrease of compression and the loss of length across the arthrodesis were simultaneously reduced.

Arthrodesis↗

PubMed1977

Compression bone-plating: historical considerations.

Compression of bone fragments to accelerate, or at least facilitate, bone healing was first applied in 1932 by Key to arthrodesis of the knee. Subsequently the same principle was applied to fractures, first by percutaneous pins as developed by Roger Anderson and then by implanted compression plates. Two types of compression plate have been evolved. One employs an axially oriented force produced by a separate screw or temporarily applied compression device, designed just for this purpose, as originated by Danis in 1949. The other, devised by me in 1956, is a so-called self-compressing plate, which generates compression force by inserting eccentrically placed chamfered screw-heads into slots in the plate so that the screws (as well as the bone fragments in which they are inserted) are translated toward each other. Numerous modifications of these two basic designs are now available.

Bone Plates↗

PubMed1987

Speech discrimination with an 8-channel compression hearing aid and conventional aids in background of speech-band noise.

The design for a multichannel compression hearing aid was developed from previous experimental and theoretical work in our laboratory concerning pitch perception in normal-hearing subjects. The new hearing aid, implemented with off-line digital signal processing, was tested on twenty subjects with sensorineural hearing loss using speech sounds in a background of speech-spectrum noise. Five signal-to-noise ratios (+15 to -5dB) were used at two noise levels (60 and 70 dB SPL). Hearing-loss subjects listened to these stimuli under three different conditions: a) processed by the new multichannel compression hearing aid; b) processed by a conventional hearing aid; and c) unprocessed. The performance of normal-hearing subjects with the unprocessed stimuli provided another condition against which the performance in the two hearing aid conditions could be evaluated. Both aided conditions provided improved performance over the unprocessed condition and the multichannel compression aid produced better performance than the conventional aid. In the case of 4 of the 20 subjects, with less severe gradually sloping hearing losses, the new multichannel compression aid produced near-normal performance even at low signal-to-noise ratios. Some aspects of the results also suggested that learning to use the aid was more important in the case of the multichannel compression aid than in the case of the conventional aid. These results indicate that a multichannel compression hearing aid can be very effective in some individuals with sensorineural hearing loss and is superior to a conventional hearing aid in most subjects.

Acoustics↗

PubMed1986

External compression without adjuncts.

Over the past decade many exciting and promising new approaches of delivering CPR have been studied. Considerable data have accumulated suggesting that forward flow during CPR is generated, at least in part, by the development of elevated intrathoracic pressure with an extrathoracic arteriovenous pressure difference. This mechanism, known as the "thoracic pump," has been documented during "cough-CPR" and has led to numerous attempts at optimizing the outcome by increasing intrathoracic pressure in CPR. Studies have demonstrated improved flows with simultaneous ventilation and sternal compression, with static or interposed abdominal compression, with longer duration compression, and with various combinations of these maneuvers. Other recent studies have suggested that the cardiac compression mechanism may indeed be operative, at least under certain circumstances, and that CPR may be optimized by increasing the force and rate of compression. Still others have advocated a simple change in the sequence of initiating ventilation and compression. Which, if any, of these newly advocated methods improve the outcome when applied to man remains to be established. If any of these techniques is shown to be more advantageous, its widespead use will depend on its applicability without adjuncts and its teachability to the lay public.

Heart Massage↗

PubMed1987

Regimen for improved effectiveness of intermittent pneumatic compression in deep venous thrombosis prophylaxis.

The incidence of deep venous thrombosis (DVT) was assessed in a series of 78 patients undergoing major surgical operations to compare the prophylactic effectiveness of intermittent sequential pneumatic compression alone with the simultaneous use of graduated compression stockings and intermittent sequential pneumatic compression. The diagnosis of DVT was determined with the I-125 fibrinogen-uptake test, Doppler ultrasound, maximum venous outflow by strain-gauge plethysmography, and contrast venography. The incidence of DVT in nonstockinged legs was 9% while that in the stockinged legs was 1%. The simultaneous use of graduated elastic compression stockings and intermittent pneumatic compression is more effective than pneumatic compression alone in the prevention of postoperative DVT.

Adult↗

PubMed1986

[On the compression rate for inhibiting high pressure nervous syndrome under high pressure helium atmosphere].

Bennett (1975) reported that signs and symptoms of the High Pressure Nervous Syndrome (HPNS) appeared including nausea, dizziness, tremors of the hands and arms, increased slow wave activity in electroencephalogram, especially in the theta band (4-7 Hz) with depression of alpha (8-13 Hz) and beta (20 Hz and higher) on compression with oxygen-helium to depths greater than 500 ft (16 ATA). Earlier studies have indicated that the HPNS may be controlled by use of an increased nitrogen partial pressure, slowing compression rate or excluding subject who has higher susceptibility to HPNS. For determining the effect of slowing compression rate, it was changed to new compression profile of linear compression to 31 ATA with intermediate stops in SEADRAGON-VI carried out at JAMSTEC in 1983. All divers to compressed to 31 ATA using the new rate complained few and slight signs and symptoms involved HPNS than ever experienced.

Adult↗

PubMed1985

[Thoracic outlet syndrome and its significance for surgery of the hand (on the etiology and pathogenesis of epicondylitis, tendovaginitis, median nerve compression and trophic disorders of the hand)].

At present, the term "thoracic outlet syndrome" (TOS) is used as a term to include all factors compressing the nerves and vessels situated in the outlet of the thorax and the costo-clavicular area. It is marked by neurological and vascular disorders; their manifestation can be either spontaneous or posttraumatic. In case of surgical treatment the transaxillary approach (according to Roos) proved to be the best, and is indicated in therapy-resistant TOS, in certain cases of arterial complications and in outlet obstructions of the subclavian vein. Complete resection of the first rib and the most careful removal of all fibro-muscular structures affecting the artery, vein and brachial plexus are of importance to the result of the operation. In the evaluation of cases we found surprising success with cases of lateral epicondylitis. Thus, the nerve irritation asserted as a cause in 1962 is once more confirmed. The postoperative development of 38 median nerve compressions proved to be particularly astonishing. Twenty-five of those vanished without any need for additional measures, and in eight cases definite improvement was achieved. Another important fact was observed when five median nerve compressions, previously operated upon, disappeared only after a secondary TOS-operation. These observations led to a new pathogenetic concept of median nerve compression. Apart from the common causes, the primary predisposing factor for median nerve compression is a chronic oedema due to a functional blockage of the subclavian vein, clinically and radiologically substantiated. This oedema eventually leads to a carpal tunnel syndrome, either directly on account of swelling of fibrous structures or via metabolic disorders and oxygen deficiency, thereby causing an infiltrative and proliferative reaction. In this connection, it seems interesting that the results of recent pathohistological researches suggest that the chronic oedema is the greater pathogenetic factor. The improvement of painful tendovaginitis and different disturbances in wound healing after surgical treatment of the TOS shows the importance of subclavian vein compressions. Phlebographic examination of patients who suffer from Sudeck's atrophy demonstrates significant narrowing of the subclavian vein. The increasing pressure in the subfascial space and the irritation of the lower cervical plexus and the subclavian artery can promote Sudeck's atrophy.

Adolescent↗

PubMed1985

Prediction of vertebral body compressive fracture using quantitative computed tomography.

We performed quantitative computed tomography in vitro on the first and third lumbar vertebrae in human cadavera using a dibasic potassium phosphate phantom for calibration. The quantitative computed-tomography numbers exhibited a significant positive correlation (R2 = 0.89, p less than 0.0001) with direct measurements of the apparent density of the vertebral trabecular bone. We also conducted uniaxial compression tests to failure of the vertebral bodies after removal of the posterior elements, and found that vertebral compressive strength was also correlated at a high level of significance (R2 = 0.82, p less than 0.0001) with direct measurement of the trabecular apparent density. These findings suggested the possibility that the quantitative computed-tomography values might be directly predictive of vertebral compressive strength. However, when we correlated the quantitative computed-tomography values directly with vertebral compressive strength, the results (R2 = 0.46, p less than 0.061) were suggestive but not quite significant. All vertebral bodies failed by compression of the end-plate, suggesting only a modest structural role for the cortical shell under these loading conditions. This was confirmed by comparing the compressive load to failure of twenty additional pairs of vertebrae that were tested with and without an intact vertebral cortex. Removal of the cortex was associated with approximately 10 per cent reduction in vertebral load to failure.

Aged↗

PubMed1983

Study of the effects of oral administration of CDP-choline on EEG changes and lethality induced by epidural compression in the anaesthetised cat.

The effects of repeated oral administration of cytidine diphosphate choline (CDP-choline, citicoline, Somazina) and vehicle on the EEG changes induced by epidural brain compression have been studied in the anaesthetised cat. The effects on arterial pressure and heart rate were also monitored. CDP-Choline-treated cats exhibited a statistically significant increase in resistance to the effects of mechanical compression of the brain when compared with the vehicle-treated group. In addition the onset of abnormal EEG waveforms occurred at greater levels of brain compression in drug-treated cats. CDP-Choline also imparted protection against the cardiovascular and respiratory effects of brain compression; animals were apparently less susceptible to cardiac and respiratory failure under the influence of the test compound. A statistically significant protection against the lethal effects of epidural compression was also noted in CDP-choline treated cats. It may be concluded that repeated oral treatment with CDP-Choline provides an apparent protection against the effects of acute mechanical compression of the brain.

Anesthesia↗

PubMed1994

[Color Doppler controlled compression therapy of puncture aneurysms--a noninvasive therapy concept].

After transfemoral catheterization, pseudoaneurysms can occur in about 0.1-0.05% of cases, especially after the use of large instruments and a faulty puncture technique. Today, pseudoaneurysms can be easily and accurately diagnosed with the help of duplex and color Doppler ultrasound. Apart from its diagnostic application, color Doppler ultrasound also offers a noninvasive and cheap alternative therapy mode as compared to surgical repair. The purpose of our study was to evaluate the therapeutic efficiency of an ultrasound-guided compression technique for postpunctional pseudoaneurysms. Over a 12-month period, nine patients were sonographically diagnosed with postpunctional pseudoaneurysm of the femoral superficial artery. The compression therapy was only applied if no contraindications (e.g. rupture, retroperitoneal site of the lesion, infection, large haematoma with suspected ischaemia, and necrosis) were present. Two of the nine patients were primarily excluded from therapy because of a high risk of rupture or a large haematoma. Five patients of the remaining seven have been successfully treated. In one of the unsuccessfully treated patients, only a partial thrombosis of the aneurysm was obtained, followed by complete spontaneous thrombosis 4 days later. The second compression failed because of the 4-month time interval between angiography and compression therapy. A successful therapy clearly depended on the time interval between puncture and compression. We could not find any significant correlation between the aneurysm volume and the duration of compression. Color Doppler ultrasound-guided therapy is a noninvasive easily applicable, and cheap alternative to surgical repair of postpunctional pseudoaneurysms.

Adult↗

PubMed1994

[Compression therapy in post-thrombotic syndrome].

The most important aim of compression therapy in postthrombotic legs is prevention of dermatosclerosis and ulcus cruris. For the acute stage of leg swelling and for venous ulceration we prefer compression bandages ("therapy phase"). The effect of compression therapy with bandages depend on the material of the used bandages (short or long-stretch bandages), the stretching the bandages are applied with, the number of layers, the local pads and on well done application of the bandages. After removal of oedema compression therapy should be continued with medical compression stockings ("maintenance phase"). Compression stockings should be fit on carefully and be checked from time to time to guarantee their application by the patient.

Bandages↗

PubMed1994

[Compression stockings in treatment of lower leg venous ulcer].

AIM: of the study was to evaluate the efficiency of medical compression stockings, which do not require special application techniques, compared with short stretch bandages for treating leg-ulcers. STUDY-DESIGN AND PATIENTS: Prospective trial on a total of 50 out-patients with leg-ulcers randomly allocated into two therapy-groups: 25 patients got firm compression bandages using short stretch material (Rosidal K), 25 patients were treated by medical compression stockings (Thrombo+Sigvaris 503). Due to the statistically significantly lower mean age and longer duration of the ulcers in the Sigvaris-group only restricted comparison of the treatment groups is possible. Local dressings in both groups consisted of a nonadherent, absorbing material (Vliwin) with an individually modelled rubber foam pad on top. The end-point was complete ulcer-healing, in a period of 3 months. METHODS: The following parameters were measured: area of ulceration, compression-pressure, tcPO2 and Laser-Doppler-Fluxmetry at the ulcer border before and after 3 minutes of arterial occlusion, venous volume and venous filling index by air plethysmography (APG) with and without compression. RESULTS: After 3 months 21 cases (84%) were healed in the Sigvaris-group and 13 (52)% in the Rosidal-group. This significant difference may be partly explained by the more favorable starting condition of the stocking-patients. However, one major advantage of stockings over short stretch bandages is the maintenance of an adequate pressure if they are not renewed for several days. CONCLUSION: Therapy of venous ulcers by medical compression stockings may be an effective approach for fit and cooperative patients.

Adult↗

PubMedDate not supplied

Beta-cyclodextrin as a direct compression excipient compared to conventional ones.

Beta-Cyclodextrin was evaluated as a direct compression excipient and compared to conventional excipients. The measured physical properties included particle size and particle size distribution, flowability, bulk density, and hygroscopicity. Compression characteristics were evaluated by measuring compactibility, compression force-hardness profiles and compression force requirements. The materials studied were directly compressed into tablets and the produced tablets were evaluated with regard to uniformity of weight, disintegration time, crushing strength and friability. The results suggest that beta-cyclodextrin is a good candidate as a direct compression excipient.

Chemistry, Pharmaceutical↗

PubMed1994

Time compression and release from masking in adults and children.

We studied the effect of speech time compression (TC), alone and in the presence of competing babble, in 24 adults and 24 children. Both adults and children showed significant decreases in speech recognition when speech was compressed at a rate of 60 percent, as compared with recognition of normal-rate speech. Listening to time-compressed speech in a binaural homophasic mode resulted in better speech recognition than in a monaural mode for both adults and children. When speech was antiphasic, both adults and children demonstrated a release from masking for normal-rate (0% compression) and 60 percent time-compressed speech. When both groups listened to speech that had been compressed and presented in a babble, their performance supported a multiplicative distortion theory. The results support the importance of binaural hearing for optimizing auditory performance in difficult listening situations.

Adult↗

PubMed1994

Graduated compression stockings in the prevention of postoperative venous thromboembolism. A meta-analysis.

BACKGROUND: The effectiveness of graduated compression stockings in prophylaxis of postoperative venous thromboembolism is unclear to many physicians. Surveys show there is considerable variability in their use and their perceived effectiveness. We undertook to establish, by a systematic overview of the literature, the effectiveness of graduated compression stockings in the prophylactic setting of postoperative venous thromboembolism. METHODS: Studies published between 1966 and June 1992 were identified through the MEDLINE database, with a search in all languages, through reviews of Current Contents, and including references cited in identified articles. Articles were selected for initial analysis if they assessed the use of graduated compression stockings for the prophylaxis of venous thromboembolism, and if the stocking group was compared with an untreated or unconfounded control group. Criteria were established a priori, to select only studies with sound methods. On the basis of these criteria, 12 studies were identified for the combined analysis. Each eligible study was independently analyzed for the risk of development of deep venous thrombosis in the control and stocking groups, and this was expressed as an odds ratio. Odds ratios were combined across studies by means of the Mantel-Haenszel chi 2 procedure. The data were analyzed separately for orthopedic surgery because of its high risk for venous thromboembolism. RESULTS: Eleven of the 12 studies were in moderate-risk surgery (abdominal, gynecologic, and neurosurgery); the summary odds ratio was 0.28, which translates into a risk reduction of 68% (95% confidence interval, 53% to 73%), which is statistically significant (P < .0001). In the one study in orthopedic surgery that was eligible for inclusion, the odds ratio was 0.50 (95% confidence interval, 0.19 to 1.29; P = .17). CONCLUSIONS: The use of graduated compression stockings for prophylaxis of venous thromboembolism after moderate-risk surgery results in a significant risk reduction. It is unknown whether the use of graduated compression stockings in combination with other forms of prophylaxis results in further risk reduction. The efficacy of graduated compression stockings in orthopedic surgery has been assessed by only one study that used sound methods, hence no definitive conclusions can be made in these high-risk patients.

Bandages↗

PubMedDate not supplied

Adaptive compression of the ambulatory electrocardiogram.

Previous use of the MIT/BIH arrhythmia database, on analog tape, to investigate compression of ambulatory ECG data by average beat subtraction, residual differencing, and Huffman coding of the residuals had shown that with a quantization level of 35 mu V and a sample rate of 100 samples per second, it was possible to store ECG data with average data rates of 174 bits per second (bps), but because of the variation in ECG signals, data rates for different records ranged from 144 bps to 230 bps. In a practical storage system, it is desirable to fix the maximum data rate and store data with a minimum of distortion. For this study the previous compression algorithm was modified to adapt its quantization level to different ECG signal conditions. Two adaptation strategies were investigated. Both adapt the quantization-step size according to the number of bytes required for storing the coded signal, beat arrival times, and beat classifications. The new compression algorithm was tested with data from the MIT/BIH database on CD ROM. With the more successful of the two strategies, the adaptive compression algorithm stored MIT/BIH records with a difference of only 0.8 bps between the record with the highest data rate and the record with the lowest data rate. The average data rate for the entire database was 193.3 bps. Signal-to-compression noise ratios varied from record to record and varied over time for a given record. Average signal to compression noise ratios varied from 26.82 to 532.83.

Algorithms↗

PubMed1995

[A comparison of compression stockings of different pressures with lower leg edema in spinal cord injury or lesions patients].

We tested 80 spinal cord injury or lesion patients admitted to Department of Rehabilitation Medicine of Chang Gung Memorial hospital from Jan, 1994 to Aug, 1994, in order to assess the effectiveness of compression stockings of different pressures. The study group consisted of patients who, after leaving bed for 4 hours, had a volume change in the lower extremities greater than 50 c.c., as measured by a specially designed water bucket. One of the lower limb was used as the control group and the other limb was used as the experimental group. Different stocking compression pressure, 12 mmHg 20 mmHg, and 30 mmHg, were used for the experimental limb. No placebo stocking was used in the control group. Change in the lower limb volume and degree of comfort after leaving bed for 4 hours were measured. The experimental results reveal that wearing stocking with compression pressure, 12 mmHg, 20 mmHg, 30 mmHg, had therapeutic effects (P < 0.01). The therapeutic effects of the 12 mmHg stocking was less than the 20 mmHg and 30 mmHg stocking. There was no significant difference between the therapeutic effects of the 20 mmHg and 30 mmHg stocking. As for the degree of comfort, 12 mmHg was better than 20 mmHg, and 20 mmHg better than 30 mmHg. When choosing the type of compression stocking to treat lower leg edema in spinal cord injury or lesion patients, we suggest starting with 20 mmHg compression pressure stockings would be a better choice, as they are cheaper, more comfortable to wear and can provide the same therapeutic effects as 30 mmHg compression stockings.

Adult↗

PubMed1996

[Treatment of post-coronarography femoral false aneurysm by compression, guided by Doppler echography].

MATERIAL AND METHODS: We evaluated the role of color Doppler US-guided compression in the non-invasive treatment of femoral artery pseudoaneurysms after cardiac catheterization, including 22 PTCA procedures. The diagnosis of 32 pseudoaneurysms in 32 patients was accomplished by detection of the typical US-Doppler pattern consisting of the swirling color Doppler flow and the "to and fro" pulsed Doppler waveform at a mean 3.6 days (1 to 14) after the cardiac catheterization. Thirteen patients had multiple cavity pseudoaneurysms (2 to 4). All the patients immediately underwent compression therapy. RESULTS: Treatment was successful in 42/49 cavities (86%) and 25/32 patients (78%), usually after 1 to 3 compression cycles of 6 to 8 minutes duration. Only one recurrence was noted at the 24 hour US-Doppler follow-up. In all cases, pain relief during compression was an excellent clinical sign of hemostatic plug formation and conversion from pseudoaneurysm to simple hematoma. Failures occurred among patients under high dose anticoagulants in spite of 4 to 10 compression cycles. COMMENTARY: In conclusion, color Doppler US-guided compression of post-cardiac catheterization pseudoaneurysms should be the first line therapeutic modality, even in cases of multiple cavities and among patients under effective anticoagulation therapy.

Adult↗