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PubMed1987

[Research on the incidence of decompression sickness in compressed air works. The development of its recent five years' study].

Compressed air works have been used as the safest construction work for the basic underground or underwater compressed shield or caisson works in Japan; however, the workers who were exposed to the compressed fields must have put themselves at risk of decompression sickness. Decompression sickness is generally considered to be due to the bubble effects and the bubbles originate from the supersaturated gas dissolved in the blood and other tissues. The standard decompression schedule by the Ministry of Labor has been practically applied at the end of compressed air works, and the laborers decompress slowly from the bottom pressure to the surface according to the schedule. It is difficult to completely prevent the sickness and the average percentage of contracting "bends," using the Japanese standard decompression schedule, is considered to be 0.54%. But previous papers reported higher incidences from 1.42 to 3.3% or more. We have continued an actual investigation on the incidence, and the number of the exposed trials amounted to nearly a hundred thousand. These data were compared between recent five years' group and before. Eventually, it was ascertained that the incidence has been significantly decreased in the recent five years; however, greater care in occupational safety control is still needed.

Adult↗
PubMed2002

[Effects of fast decompression on prostaglandins content in cerebral tissue of guinea pigs].

Objective. To investigate the effect of fast decompression on prostaglandins in cerebral tissue. Method. 26 guinea pigs were divided into 2 groups randomly. The animals in group FDC (group 1) were treated with fast decompression and formed decompression sickness, but those in control group (group 2) were not treated with decompression. The contents of prostaglandin E2 (PGE2), 6-keto-prostaglandin F1a (6-K-PGF1a) and thromboxane B2 (TXB2) in cerebral tissue of the animals were determined by enzyme immunoassay. Result. The content of PGE2 in cerebral tissue of FDC animals was twice as much as that in control animals. The content of TXB2 in cerebral tissue of FDC animals was 3 times as high as that in control animals, and that of 6-K-PGF1a in cerebral tissue of FDC animals was 2.6 times as that in control animals. It showed very significant differences as compared with control group (P<0.01). Conclusion. The content of PGs in cerebral tissue increased markedly after fast decompression, and may cause cerebral injury.

6-Ketoprostaglandin F1 alpha↗
PubMed2002

Decompression sickness during construction of the Great Belt Tunnel, Denmark.

Thirteen cases of decompression sickness (DCS) occurred during the construction of the 8-km long railway tunnel under the Great Belt in Denmark between January 1992 and February 1996. 320 compressed air workers were subjected to 9018 pressure exposures in four tunnel boring machines. Overall DCS incidence was 0.14%. Working pressures ranged between 0.25 bar (1.25 atm abs or 126.3 kPa) and 2.95 bar (3.91 atm abs or 396.3 kPa) and working times ranged between 2 minutes and 339 minutes. During the first 1798 pressure exposures 7 DCS cases occurred using French air decompression tables from 1974. The following 7220 exposures were then decompressed in accordance with the newly issued French air decompression tables of 1992. After changing schedules 6 DCS cases occurred and DCS incidence was reduced to 0.08%. Two of the first seven DCS cases had permanent residual symptoms after recompression treatment. All DCS cases, except one, occurred among the 30% of exposures that imposed the greatest decompression stress. DCS incidence among these exposures was 0.42%.

Adult↗
PubMed1987

The effect of extended O2 prebreathing on altitude decompression sickness and venous gas bubbles.

The purpose of this study was to determine the effect of extended O2 prebreathing on symptom and bubble incidence during decompressions simulating extravehicular activity. The 38 subjects breathed O2 for a 6-h period prior to decompression to 4.3 psi. The subjects performed upper body exercise for 6 h. Subjects were monitored with a Doppler bubble detector and were encouraged to report all symptoms. Eight subjects were exposed to the same protocol after an 8-h prebreathe. Venous bubbles were detected in 18 of 38 subjects decompressed after the 6-h prebreathe. Four of these subjects reported symptoms of altitude decompression sickness. No symptoms or bubbles were detected in the eight subjects who had prebreathed 8 h. The incidence of symptoms and bubbles when combined with prior data on 3.5- and 4.0-hour prebreathes showed an inverse correlation to pre-breathing time. The incidence of symptoms was higher than has been reported for subjects exposed to decompression of shorter duration with less activity.

Adult↗
PubMed1987

A likelihood analysis of experiments to test altitude decompression protocols for shuttle operations.

The principle of maximum likelihood and the method of linear regression both are used to fit mathematical models to experimental data, but likelihood can be applied to binary data such as the outcome of a decompression, whereas linear regression cannot. Maximum likelihood was applied to 548 individual altitude exposures from 30 experimental pressure profiles tested by NASA and the Air Force. Twelve decompression models were studied including modified Haldane models and models which assume that stationary bubbles cause Type I decompression sickness. The data was best represented by a model in which a bubble in tissue is surrounded by a diffusion barrier, but this representation was statistically indistinguishable from a single tissue Haldane model with a halftime of 508 min. By providing a quantitative measure of the agreement between theory and data, the principle of maximum likelihood offers an opportunity for improving the understanding of decompression mechanisms and for developing safer and faster decompression procedures.

Altitude↗
PubMed2002

Surgical decompression for cerebral oedema in acute ischaemic stroke.

BACKGROUND: The high mortality that follows a large cerebral infarction is in part due to brain oedema. Oedema causes mass-effect with raised intracranial pressure and herniation. Medical therapies are used to reduce intracranial pressure but outcome is poor in spite of treatment. Decompressive surgical techniques that attempt to relieve high intracranial pressure due to oedema have been described, but their efficacy in reducing case fatality and disability is uncertain. OBJECTIVES: To compare medical therapy plus decompressive surgery with medical therapy alone on the outcomes death and 'death or dependency' in patients with an acute ischaemic stroke complicated by clinical and radiologically confirmed cerebral oedema. SEARCH STRATEGY: We searched the Cochrane Stroke Group Trials Register (4 October 2001). In addition, we searched the following electronic databases: the Cochrane Controlled Trials Register (Cochrane Library, issue 3, 2001), MEDLINE (1966 - April 2002), EMBASE (1980 - April 2002), and SCISEARCH (to April 2002). We also searched the reference lists of all relevant articles retrieved and contacted individual investigators and experts in the field. SELECTION CRITERIA: Randomised controlled studies comparing the outcome of treatment with decompressive surgical intervention with treatment not involving surgery. We aimed to include only those studies with low or moderate risk of bias. DATA COLLECTION AND ANALYSIS: Titles retrieved by searching were assessed for relevance by one author. Data were extracted independently by two authors with discussion to resolve differences. Relevant sub-group analyses were planned and we planned to calculate Peto odds ratios with 95% confidence intervals. MAIN RESULTS: Over 9000 citations were retrieved and inspected for relevance. We identified no randomised-controlled trials to include in a meta-analysis. Five observational studies reporting comparative data were found along with a number of small series and single case reports. Two ongoing randomised-controlled trials were identified. REVIEWER'S CONCLUSIONS: There is no evidence from randomised-controlled trials to support the use of decompressive surgery for the treatment of cerebral oedema in acute ischaemic stroke. Evidence from randomised-controlled trials is needed to accurately assess the effect of decompressive surgery.

Brain Edema↗
PubMed2005

Surgical decompression versus local steroid injection in carpal tunnel syndrome: a one-year, prospective, randomized, open, controlled clinical trial.

OBJECTIVE: Optimal treatment of carpal tunnel syndrome (CTS) has not been established. This study compared the effects of local steroid injection versus surgical decompression in new-onset CTS of at least 3 months' duration. METHODS: In a 1-year, prospective, randomized, open, controlled clinical trial, we studied the effects of surgical decompression versus local steroid injection in 163 wrists with a clinical and neurophysiologic diagnosis of CTS. Clinical assessments were done at baseline and at 3, 6, and 12 months after treatment. The primary end point was the percentage of wrists that reached a >or=20% improvement in the visual analog scale score for nocturnal paresthesias at 3 months of followup. Statistical analysis was done by Student's t-test for continuous variables and by chi-square test for categorical variables. Analyses were performed on an intent-to-treat basis. P values less than 0.05 were considered statistically significant. RESULTS: Both treatment groups had comparable severity of CTS at baseline. Eighty wrists were randomly assigned to the surgery group and 83 wrists to the local steroid injection group. In the intent-to-treat analysis, at 3 months of followup, 94.0% of the wrists in the steroid injection group versus 75.0% in the surgery group reached a 20% response for nocturnal paresthesias (P = 0.001). At 6 and 12 months, the percentages of responders were 85.5% versus 76.3% (P = 0.163) and 69.9% versus 75.0% (P = 0.488), for local steroid injection and surgical decompression, respectively. CONCLUSION: Over the short term, local steroid injection is better than surgical decompression for the symptomatic relief of CTS. At 1 year, local steroid injection is as effective as surgical decompression for the symptomatic relief of CTS.

Carpal Tunnel Syndrome↗
PubMed1975

[Indication and prognosis of the transethmoidal decompression of the optical nerve in posttraumatic amaurosis (author's transl)].

In 8 patients with unilateral posttraumatic amaurosis a transethmoidal decompression of the optical nerve was performed. In 4 patients the vision returned completely after operation, 1 patient showed only a partial improvement and in 3 cases the amaurosis remained unchanged. These results agree with those reported by Japanese authors (Sugita et al., 1965; Fukado, 1968) and suggest, that opposite to the neurosurgical transfrontal-intradural resection of the roof of the optical canal the rhinosurgical transethmoidal decompression of the optical nerve may improve the prognosis of the posttraumatic amaurosis, espcially, if the decompression can be done as soon after trauma as possible. Further advantages of this surgical method are the smaller risk, the shorter operation time and the preservation of olfaction. It is emphasized that the rhinologist cannot indicate the decompression of the optical nerve without consulting the ophthalmologist and the neurologist. Contraindications are lesions of the bulbus oculi and the fundus, lesions of the chiasma opticum and a posttraumatic amaurosis caused by a sinus-cavernosus-fistula. Regarding the experiences gained by rhinosurgeons so far the early transethmoidal decompression seems to be indicated, if a unilateral impairment of vision exists right after the trauma or develops within the next 24-48 hrs and if there is no damage to the bulbus and the fundus.

Adult↗
PubMed1983

Bubbles and hematologic alterations in intracranial veins during experimental decompression sickness.

Rats were exposed to 6.1 bar (abs.) air for 90 min and subsequently decompressed to the ambient pressure. After a decompression rate of 6.8 bar/min pial veins and superior sagittal sinuses were found to contain gas bubbles; no intravascular bubbles were observed subsequent to a decompression rate of 1.5 bar/min. Under the electron microscope platelet aggregates were observed at both the electron-dense layer of the blood-bubble interface and in pial veins with no bubbles. It is concluded that during decompression sickness bubbles and both activation and aggregation of platelets occur in intracranial veins. Subsequent venous congestion may contribute to the neuronal lesions and symptoms of acute decompression sickness.

Animals↗
PubMed1998

[Early trans-sphenoid decompression in indirect traumatic optic neuropathy].

BACKGROUND: Indirect traumatic optic neuropathy represents a severe, potential vision-threatening disease process that requires close interdisciplinary cooperation for treatment. In general, any therapy has been discussed controversially in the literature. Based upon experiences with spinal cord trauma, high-dose steroid therapy is recommended initially to minimize secondary consequences following orbital trauma. The usefulness of surgical decompression of the optic nerve has been confirmed in several studies but is still not recommended in principle. PATIENTS AND METHOD: In nine consecutive patients with known indirect traumatic optic neuropathy and marked losses of vision, transsphenoidal optic decompressions were carried out with simultaneous systemic megadose steroid therapy. RESULTS: A postoperative increase in visual acuity from 1/35 to 10/20 occurred in five patients, while no improvement in visual acuity could be achieved in the other four patients. DISCUSSION AND CONCLUSION: Previous reports have indicated that some authors will not recommend surgical decompressions if a loss of sight or no light perception occurs directly after an accident. This situation was seen in seven of our patients. The visual acuity of four patients remained no light perception in spite of surgical treatment. In three other patients, an increase in visual acuity from amaurosis improved to 1/35, 4/20 and 8/20, respectively, following early decompression combined with steroids. This experience together with the positive results of other studies supports carrying out decompressions of the optic nerve, even when an amaurosis occurs directly after trauma.

Adolescent↗
PubMed2002

[Undercutting decompression versus laminectomy. Clinical and radiological results of a prospective controlled trial].

The aim of the current study was to evaluate the clinical outcome after laminectomy or undercutting decompression in patients with lumbar spinal stenosis (LSS) without apparent signs of instability. In a prospective controlled, nonrandomized trial 1 year after operation, two groups of patients were compared. Out of 85 consecutive patients, treated from 1998 to 1999 in an orthopedic university clinic for symptomatic LSS, decompression without simultaneous fusion was performed in 40 cases. In group I ( n=13) a laminectomy was done and in group II ( n=27) an undercutting of the vertebral arch and facet joints. The main outcome measure was the Oswestry Low Back Disability Score. Subjective complaints, visual analog scale (VAS), claudication distance, analgesic demands, and radiomorphometric parameters following the procedure of Dupuis and Nash/Moe at 6 and at 12 months after the operation were secondary objective criteria. One year postoperatively the main outcome measure showed no significant difference between the two groups, although group II had shown better results ( p=0.0195) 6 months postoperatively. The required analgesics could be significantly lowered in group II compared with group I at 12 months ( p=0.0011). The remaining secondary outcome measures showed no statistically significant differences. The extent of decompression in LSS without apparent instability did not influence the outcome. If there is any doubt intraoperatively about the adequate amount of decompression of the lumbar spinal canal, undercutting decompression should be extended to laminectomy without fear of consecutive segmental instability.

Aged↗
PubMed2000

[The value of core decompression in treatment of femur head necrosis].

Core decompression of the necrotic area for treatment of idiopathic osteonecrosis of the femoral head was developed and published by Ficat and Arlet in 1962 within the scope of their "Functional exploration of bone". The mode of action is attributed to a reduction of the intramedullary pressure in the bony compartment of the femoral head. The possibilities of repair and bone regeneration following core decompression are still discussed controversially. Core decompression is a common but not generally accepted procedure in the treatment of idiopathic osteonecrosis of the femoral head. After first publications of positive mid- and long-term effects, some subsequent studies judged it as an ineffective and high-risk method. Analysis of the literature shows that the effectiveness of core decompression depends on the stage of osteonecrosis at the time of surgical intervention. Prognosis is influenced by the extent and location of the necrotic area, the presence and amount of head depression, and continued risk factors--mainly corticoid medication. The best prognosis can be given for patients with a small, medial-centrally located necrosis without head depression. The classification according to Ficat appears to be insufficient, as the extent and localization of the necrotic area are not assessed. Magnetic resonance imaging has become a diagnostic gold standard, as radiographic diagnosis showed poor sensitivity and specificity, especially in the early stages of the disease. As an essential part, MRI was integrated into the new classification of the "Association Internationale de Recherche sur la Circulation Osseuse" (ARCO). On account of the literature and our own experience, treatment by core decompression can be recommended in cases of reversible early stages of osteonecrosis (ARCO 1), as well as in those cases of irreversible early stages (ARCO 2) that show a medial or central location of the necrosis with an extent of less than 30% of the femoral head. Once the disease reaches the irreversible early stage, complete recovery cannot be expected. In these cases only reduction of pain and retardation of the natural course of the osteonecrosis are possible to gain time until total hip replacement is unavoidable.

Decompression, Surgical↗
PubMed2003

Early decompressive craniotomy in children with severe traumatic brain injury.

INTRODUCTION: Decompressive craniectomy remains a controversial procedure in the treatment of raised intracranial pressure (ICP) associated with post-traumatic brain swelling. Although there are a number of studies in adults published in the literature on this topic, most commonly as a salvage procedure in the treatment of refractory raised ICP, there are few that investigate it primarily in children with head injuries. AIM: Our aim was to report the experience with decompressive craniotomy in children with severe traumatic brain injury (TBI) at the Red Cross Children's' hospital. METHODS: This study reports five patients in whom decompressive craniectomy or craniotomy with duraplasty was used as an early, aggressive treatment of raised ICP causing secondary acute neurological deterioration after head injury. The rationale was to save the patient from acute cerebral herniation and to prevent exposure to a prolonged course of intracranial hypertension. RESULTS: All patients benefited from the procedure, demonstrating control of ICP, radiological improvement and neurological recovery. Long-term follow-up was available, with outcome assessed at a minimum of 14 months after injury. DISCUSSION: The early approach to the use of decompressive craniotomy in the treatment of severe traumatic brain injury (TBI) with secondary deterioration due to raised ICP is emphasised. A favourable outcome was achieved in all of the cases presented. The potential benefit of decompressive craniectomy/craniotomy in the management of children with severe TBI is discussed.

Brain Injuries↗
PubMed2003

Transient marrow edema syndrome of the hip: results after core decompression. A prospective MRI-controlled study in 22 patients.

BACKGROUND: Transient marrow edema syndrome (TMES) of the hip is a disease of acute onset and severe functional disability. There is histological evidence for an ischemic etiology of TMES of the hip. Core decompression as applied for avascular necrosis (AVN) of the hip is therefore a therapeutic alternative to conservative therapy, the latter leading only to a reduction of symptoms but never a shortening of the course of the disease. METHODS: Between January 1998 and June 2000, 22 hips with TMES were treated with core decompression in our department. TMES was diagnosed by exclusion. MRI was done preoperatively and at 6 months postoperatively. The postoperative MRI result was classified into three categories. RESULTS: After an average of 7.2 (range 1-30) days, all patients were pain-free after core decompression. In 2 patients, TMES progressed to AVN despite core decompression. All others had no signal alterations of the head of the femur on MRI after 6 months. The postoperative Harris Hip Score (HHS) in patients with TMES was on average 93.7 (range 77-95); in patients with AVN, the postoperative HHS was 47 (range 45-49). CONCLUSION: Our results demonstrate that core decompression of the hip significantly shortens the natural course of disease of TMES of the hip.

Adult↗
PubMed2006

No changes in lung function after a saturation dive to 2.5 MPa with intermittent reduction in Po2 during decompression.

Decompression stress and exposure to hyperoxia may cause a reduction in transfer factor of the lung for carbon monoxide and in maximal aerobic capacity after deep saturation dives. In this study lung function and exercise capacity were assessed before and after a helium-oxygen saturation dive to a pressure of 2.5 MPa where the decompression rate was reduced compared with previous deep dives, and the hyperoxic exposure was reduced by administering oxygen intermittently at pressures of 50 and 30 kPa during decompression. Eight experienced divers of median age 41 years (range 29-48) participated in the dive. The incidence of venous gas microemboli was low compared with previous deep dives. Except for one subject having treatment for decompression sickness, no changes in lung function or angiotensin converting enzyme, a marker of pulmonary endothelial cell damage, were demonstrated. The modified diving procedures with respect to decompression rate and hyperoxic exposure may have contributed to the lack of changes in lung function in this dive compared with previous deep saturation dives.

Adult↗
PubMed2002

Unilateral decompressive craniectomy for children with severe brain injury. Report of seven cases and review of the relevant literature.

UNLABELLED: Severe head injuries in children (under 15 years of age) have many features that differentiate them from head injuries in adults. In such cases, non-surgical treatment cannot always prevent fatal herniation. We report on seven cases of children with severe head injury, presenting with decorticate posturing and treated by unilateral decompressive craniectomy. The aim of the unilateral decompressive craniectomy was to decompress the midbrain and the brainstem. Post-operatively, all patients showed good recovery within 5 weeks (Glasgow Coma Scale score 15). The alternative treatment modalities are discussed critically in an attempt to determine the value of the unilateral decompressive craniectomy procedure and to define the clinical parameters that might identify those children most likely to benefit from this technique. CONCLUSION: the unilateral decompressive craniectomy has an advantage over non-surgical treatment of children with severe brain injury and should be considered in their management.

Adolescent↗
PubMed2004

Circumferential decompression of the foramen magnum for the treatment of syringomyelia associated with basilar invagination.

Posterior fossa decompression utilizing suboccipital craniectomy and duraplasty remains the standard surgical treatment for Chiari-associated syringomyelia. In the presence of basilar invagination, anterior decompression, typically transoral odontoidectomy, or posterior decompression may be performed. We report two cases in which anterior and posterior (circumferential) decompression of the foramen magnum was used to treat cervical syringomyelia successfully. These cases demonstrate that circumferential decompression of the foramen magnum may be necessary in some cases of cervical syringomyelia associated with basilar invagination and Chiari malformation.

Adult↗
PubMed1995

Application of the mechanical oscillator technique to the investigation of EVA decompression.

The ultrasonic bubble detection technique has been used as a versatile tool in the investigation of hypobaric decompression procedures for the last two decades. However, this method can only detect relatively large bubbles > 30-50 micrometers (usually in venous blood) and not the very first stages of bubble formation. Recently, the mechanical oscillator technique has been applied in air diving trials in order to detect small blood density changes due to hypothetical fluid shifts. However, sharp density drops were found in the decompression process, and these have been attributed to gas bubble formation. In this study, this method was applied together with Doppler controls to a series of altitude decompressions to 300 and 500 hPa, which represents the range of EVA operational pressures currently used or planned. Six subjects participated in both series; the oscillator sample tube could be pressurized. By the application of pressure on a blood sample containing questionable gas bubbles, these are reduced in volume, like in recompression therapy, and thus the density of the sample is increased. This effect has been shown in all 6 subjects undergoing decompression to 300 hPa, whereas in the 500 hPa series only 3 out of 6 subjects corresponded with gas phase formation immediately after decompression. Typically, Doppler bubbles appeared only after some latency time between 20 and 60 min; after this time, the density effect had nearly vanished. It is concluded that the mechanical oscillator technique represents a complementary research instrument to the Doppler method, because it is able to deliver a quantitative resolution of the early stage of gas phase formation.

Aerospace Medicine↗