Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Decompression”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 901 records · Page 50Linked to original sources
PubMed1995

Quantification of lumbar nerve root decompression using somatosensory-evoked potentials.

Intraoperative somatosensory-evoked potential (SSEP) data were collected prospectively in a consecutive series of patients with an acute lumbar herniated nucleus pulposus (HNP). Each patient underwent an open limited diskectomy, hemilaminotomy, and partial foraminotomy. The sequence of diskectomy and bony decompression was randomized, and the extent of foraminotomy was standardized. SSEP data were recorded after each operative procedure and were coded for blind interpretation. SSEP tracings were compared with each patient's baseline for changes in latency and amplitude. In the overall study, changes in amplitude and latency produced by diskectomy versus bony decompression were not statistically significant. In the six patients with lateral recess stenosis (LRS), a statistically significant reduction in latency was observed after bony decompression (averaging -2.05 ms) compared with diskectomy (-0.62 ms). In patients with underlying LRS and a HNP, minimally invasive techniques addressing the disc only may be inadequate to decompress a lumbar nerve root.

Adolescent↗
PubMed1995

Quantitative magnetic resonance imaging predicts clinical outcome of core decompression for osteonecrosis of the femoral head.

OBJECTIVE: To determine whether the course of femoral head osteonecrosis after core decompression can be predicted from the extent of necrotic bone in the preoperative magnetic resonance imaging (MRI). METHODS: In 31 femoral head lesions (Ficat stage I or II), the percentage volume of necrotic bone was calculated by dividing the sum of the necrotic areas from all MRI slices by the sum of the femoral head areas. Osteonecrosis risk factors, pain scores, and the need for further surgery were assessed at a minimum of 12 mo post-core decompression. Clinical outcomes were considered good when post-core decompression pain scores improved and further surgery was not required. RESULTS: Fourteen of the 15 hips with good outcomes after a mean followup of 32 mo had less than 21% femoral head involvement. All 16 hips with poor outcomes after a mean followup of 17 mo had more than 21% of the femoral head affected. CONCLUSION: Quantitative MRI of femoral head necrosis was a useful predictor of clinical outcome following core decompression.

Adult↗
PubMed1996

["Functional" neurovascular decompressive surgery of cranial rhino- base in headaches with rhinogenic triggering].

Today one must include neurovascular decompression of the rhino-cranial base among the various forms of functional nasal surgery and the classical chapter on "Cephalea of rhinological origin" must be reviewed. In fact, all those forms of "apparently primary" headaches (i.e. migraine with and without aura, cluster headache, chronic paroxysmal migraine, tension headache) which have a central-peripheral etiopathogenesis due to a documented (CT) reduction in the volume of the "subcribriform ethmoid-sphenoidal chambers" affecting the hemoangiokinetics of endo-exocranial anastomotic circulation in this area. Rhino-cranial base neurovascular decompression surgery is described employing a "septo-ethmoid-sphenectomy". This surgery can either be conservative or radical, reaching the third degree monolateral with selective trigeminal-vegetative deafferentiation; this makes it possible to save the sense of smell, resolve the controlateral pain by decompressing the blood flow and even eliminate controlateral stasis. In addition, in a high percentage of cases, symptoms of neurological deficit or central irritation (i.e. visual aura, senso-motory palsy, epilepsy) disappear or are markedly improved after surgical elimination of the "peripheral rhinogenetic trigger". In a sample of 1000 of the 2124 patients who had undergone surgery from 1964 through the end of 1994, yearly follow-ups indicated that surgery cured or substantially improved 88%. On the other hand in 204 patients with similar forms of cephalea in advanced prophylaxis, 98% showed healing with "rapid disjunction of the palate" through "ortognatorhinodoncy" aimed at decompressing the neurovascular structure of the subcribrose chamber.

Headache↗
PubMed1998

Assessment of neuroforaminal decompression in degenerative spinal stenosis.

Surgical decompression of spinal stenosis is a balance between adequate removal of bone and soft tissue for an effective decompression of neural structures and a sufficient retention of bone to maintain mechanical stability of the spine. To develop an objective, reproducible technique for the assessment of neuroforaminal decompression in the adult lumbar spine, facet sparing laminectomies were performed from L1-S1 on the lumbar spines of 59 human cadavers. A series of semirigid probes in 0.5-mm increments were passed into each successive intervertebral foramen bilaterally, beginning at L2-L3. The minimum space available for the nerve root within the foramen of the lumbar spine is 3.5 mm at L2-L3, 3.9 mm at L3-L4, 4.3 mm at L4-L5 and 5.1 mm at L5-S1, as determined by three independent observers. There were no significant differences in interobserver or intraobserver measurements. There were no complications related to passage of the probes. This study provides a method for the intraoperative determination of the adequacy of neuroforaminal decompression.

Adult↗
PubMed2006

A physiological model of the interaction between tissue bubbles and the formation of blood-borne bubbles under decompression.

Under decompression, bubbles can form in the human body, and these can be found both within the body tissues and the bloodstream. Mathematical models for the growth of both types of bubbles have previously been presented, but they have not been coupled together. This work thus explores the interaction between the growth of tissue and blood-borne bubbles under decompression, specifically looking at the extent to which they compete for the common resource of inert gas held in solution in the tissues. The influence of tissue bubbles is found to be significant for densities as low as 10 ml(-1) for tissues which are poorly perfused. However, the effects of formation of bubbles in the blood are not found until the density of bubble production sites reaches 10(6) ml(-1). From comparison of the model predictions with experimental evidence for bubbles produced in animals and man under decompression, it is concluded that the density of tissue bubbles is likely to have a significant effect on the number of bubbles produced in the blood. However, the density of nucleation sites in the blood is unlikely to be sufficiently high in humans for the formation of bubbles in the blood to have a significant impact on the growth of the bubbles in the tissue.

Blood Gas Analysis↗
PubMed1984

Bubble formation in crabs induced by limb motions after decompression.

In vivo bubble formation was studied in the megalopal stage of the crab Pachygrapsus crassipes. The animals were equilibrated with elevated argon, nitrogen, or helium pressures then rapidly decompressed to atmospheric pressure. Voluntary motions induced bubble nucleation in leg joints after exposures to as low as 2 atm nitrogen (gauge pressure). Delays of several minutes sometimes passed between decompression and bubble formation. Mechanically stimulating the animals to move their legs increased this bubble formation, whereas immobilizing the legs before gas equilibration prevented it, even in animals decompressed from 150 atm nitrogen. We conclude that preformed nuclei are not responsible for bubbles developing in the legs of this animal. Instead, tribonucleation of bubbles apparently occurs as a result of limb motions at relatively low gas supersaturations.

Animals↗
PubMed1989

Effect of inert gas switching at depth on decompression outcome in rats.

The present investigation was performed to determine whether inert gas sequencing at depth would affect decompression outcome in rats via the phenomenon of counterdiffusion. Unanesthetized rats (Rattus norvegicus) were subjected to simulated dives in either air, 79% He-21% O2, or 79% Ar-21% O2; depths ranged from 125 to 175 feet of seawater (4.8-6.3 atmospheres absolute). After 1 h at depth, the dive chamber was vented (with depth held constant) over a 5-min period with the same gas as in the chamber (controls) or one of the other two inert gas-O2 mixtures. After the gas switch, a 5- to 35-min period was allowed for gas exchange between the animals and chamber atmosphere before rapid decompression to the surface. Substantial changes in the risk of decompression sickness (DCS) were observed after the gas switch because of differences in potencies (He less than N2 less than Ar) for causing DCS and gas exchange rates (He greater than Ar greater than N2) among the three gases. Based on the predicted gas exchange rates, transient increases or decreases in total inert gas pressure would be expected to occur during these experimental conditions. Because of differences in gas potencies, DCS risk may not directly follow the changes in total inert gas pressure. In fact, a decline in predicted DCS risk may occur even as total inert gas pressure in increasing.

Animals↗
PubMed2002

Validation of diving decompression tables.

Research on the validation of decompression tables is one of the common subject areas of the co-operation undertaken between the Defence and Civil Institute of Environmental Medicine, Toronto, Canada, and The Naval Academy of Gdynia, Poland. For several years now, a systematic survey of diving technologies has been conducted among the target projects financed by the Polish State Committee for Scientific Research and the Polish Navy. Among the most important problems discussed have been various aspects of decompression safety. The present paper shows a study to standardise and unify validation procedures for decompression in the Polish Navy.

Algorithms↗
PubMed2003

Age affects severity of venous gas emboli on decompression from 14.7 to 4.3 psia.

INTRODUCTION: Variables that define who we are, such as age, weight and fitness level influence the risk of decompression sickness (DCS) and venous gas emboli (VGE) from diving and aviation decompressions. We focus on age since astronauts that perform space walks are approximately 10 yr older than our test subjects. Our null hypothesis is that age is not statistically associated with the VGE outcomes from decompression to 4.3 psia. METHODS: Our data are from 7 different NASA tests where 188 men and 50 women performed light exercise at 4.3 psia for planned exposures no less than 4 h. Prebreathe (PB) time on 100% oxygen ranged from 150-270 min, including ascent time, with exercise of different intensity and length being performed during the PB in four of the seven tests with 150 min of PB. Subjects were monitored for VGE in the pulmonary artery using a Doppler ultrasound bubble detector for a 4-min period every 12 min. There were six design variables; the presence or absence of lower body adynamia and five PB variables; plus five concomitant variables on physical characteristics: age, weight height, body mass index, and gender that were available for logistic regression (LR). We used LR models for the probability of DCS and VGE, and multinomial logit (ML) models for the probability of Spencer VGE Grades 0-IV at exposure times of 61, 95, 131, 183 min, and for the entire exposure. RESULTS: Age was significantly associated with VGE in both the LR and ML models, so we reject the null hypothesis. Lower body adynamia was significant for all responses. CONCLUSIONS: Our selection of tests produced a wide range of the explanatory variables, but only age, lower body adynamia, height, and total PB time was helpful in various combinations to model the probability of DCS and VGE.

Adolescent↗
PubMed2003

Staged decompression to 3.5 psi using argon-oxygen and 100% oxygen breathing mixtures.

INTRODUCTION: The current extravehicular activity (EVA) space suit at 4.3 psia causes hand and arm fatigue and is too heavy for Martian EVA. A 3.5 psia EVA pressure suit requires increased preoxygenation time but would reduce structural complexity, leak rate, and weight while increasing mobility, comfort, and maintainability. On Mars, nitrogen and argon are available to provide the inert gas necessary for a fire-resistant habitat atmosphere, eliminating need for transport. This study investigated breathing argon/oxygen and 100% oxygen gas mixtures during staged decompression prior to exposure to 3.5 psia. METHOD: During this study, 40 subjects each completed 3 hypobaric exposures to 3.5 psia for 3 h in a reclined position: (A) a 4-h 25-min 14.7-psia (ground level) denitrogenation (100% oxygen breathing) prior to exposure to 3.5 psia; (B) the same as A, utilizing a 7.3-psia stage denitrogenation; and (C) the same as B, with 62% argon-38% oxygen (ARGOX) during the stage. Venous gas emboli (VGE) were monitored with echocardiography. RESULTS: Decompression sickness (DCS) incidence at 3.5 psia with ARGOX at 7.3 psia (C) was significantly higher than with oxygen breathing with or without staged decompression: there was 78% DCS for C compared with 33% and 55% DCS, respectively, for A and B. The corresponding VGE incidences were 73% (C) compared with 33% (A) and 45% (B). CONCLUSION: Preoxygenation at a 7.3-psia stage resulted in a higher DCS risk at 3.5 psia than ground level preoxygenation. It is suggested that an 8.0-psia stage pressure could eliminate this difference. Unfavorable results after preoxygenation with ARGOX indicate argon on-gassing was significant.

Adolescent↗
PubMed2004

Effects of denitrogenation on bubble formation during decompression in rabbits.

OBJECTIVE: To explore the effect of different degrees of denitrogenation on decompression sickness. METHOD: Twenty-four rabbits were randomly divided into control group, 100% oxygen inhalation 30 min group, 60 min group and 120 min group. The rabbits were anesthetized and ventilated by mechanical ventilator. After 0, 30, 60, and 120 min of denitrogenation by inhalation of 100% oxygen, the rabbits were exposed to 11000 m for 30 min. The gas bubbles generated in the body of rabbits were detected and monitored by a Doppler ultrasound detector over the precordium. RESULT: Time to bubble appearance increased with time of 100% oxygen inhalation during altitude decompression. As compared with the control group, time to bubble appearance lengthened significantly in 100% oxygen inhalation 60 min and 120 min groups (P<0.01). Time to bubble appearance was positively correlated with time of 100% oxygen inhalation (P<0.01). Accumulative number of bubbles decreased with the time of 100% oxygen inhalation. As compared with the control group, accumulative number of bubbles decreased significantly in 100% oxygen inhalation of 60 min and 120 min groups (P<0.01). Accumulative number of bubbles was negatively correlated with time of 100% oxygen inhalation (P<0.01). CONCLUSION: Denitrogenation by inhalation of 100% oxygen for 60 min and 120 min may reduce the generation of gas bubbles in rabbits when decompressed to an altitude of 11000 m.

Animals↗
PubMed1987

Decompression after repeated dives.

Seventy-six men and 7 women performed a 2nd dive in a pressure chamber under dry conditions after intervals at the surface of 10, 30, 90, or 120 min. Of these, 35 persons performed a 3rd dive after an interval of 20 or 90 min (118 repeated dives). Air was the breathing gas during all phases of the tests. During exposure to overpressure the divers exercised on a bicycle-ergometer. The decompressions for dives 2 and 3 were the same as for the first dive. After the 2nd or 3rd dive, certain symptoms of decompression sickness of the skin occurred in 5 of the 118 exposures, and 1 diver complained of muscular aches. These results suggest that no general sensitization occurred after the 1st dive. We concluded that a slightly more conservative decompression with regard to ascent velocity and profile is feasible for repeated dives.

Adult↗
PubMed1985

Fetal and maternal bubbles detected noninvasively in sheep and goats following hyperbaric decompression.

Pregnant sheep and goats were compressed with air to an equivalent depth of 49 msw (160 fsw) for bottom times ranging from 5 to 15 min. Maternal (precordial) and fetal (umbilical artery) circulation were monitored transcutaneously with a Doppler ultrasound flowmeter to determine the presence of decompression gas bubbles. It was found that the number of bubbles detected precordially in the maternal circulation exceeded the number detected in the fetal umbilical artery for any given bottom line. Additionally, bubbles were found in the fetal circulation even when the mother did not display signs of decompression sickness. Thus, avoidance of symptoms of pain-only decompression sickness in the mother is not sufficient to preclude gas phase formation in the fetus.

Age Factors↗
PubMed1979

Use of oxygen for optimizing decompression.

For over 70 years, decompression has been facilitated by the use of elevated oxygen partial pressures. Oxygen has been administered even though little is known about the proper dosage or the way in which this benefit is derived. The historical literature indicates that there is an envelope or narrow range of oxygen partial pressures that can be used. If the oxygen is too low, the incidence of decompression sickness increases; if the oxygen is too high, oxygen poisoning becomes a problem. The present study was designed to explore this oxygen envelope and to define the relationships between oxygen partial pressure, exposure time, and pressure, and to delineate their effects on pressure-reduction limits. To define the ED50 (the effective dose that produced signs of decompression sickness in 50% of the animals), we exposed 820 female albino rats to 42 experimental conditions. Results suggest that the optimum oxygen level and the size of the oxygen envelope both depend on the ambient hydrostatic pressure and the exposure time. For short "shallow" exposures, the optimum oxygen level is high and the oxygen envelope is large; for long "deep" exposures, the optimum oxygen level is reduced and the envelope is restricted.

Animals↗
PubMed1983

Gas phase formation and Doppler monitoring during decompression with elevated oxygen.

Subjects in 150 man-dives were precordially monitored with a 5-MHz Doppler ultrasound bubble detector. These measurements were made during a series of dives conducted to test decompression tables that utilize changes of breathing mixtures and a time-average PIO2 of 1.9 b during the entire decompression period. Precordially detected bubbles at depth were predictive for limb pain in divers approximately 50% of the time; however, 70% of the divers encountered bends problems in the absence of precordially detectable bubbles. Thus, while the presence of venous return bubbles can be associated with a risk factor for bends, the Doppler method appears to lack the specificity needed for personal dive monitoring. During the oxygen-breathing portions of the decompression individual bubbles could not be detected precordially. The amplitude of the Doppler-detected pulmonary artery flow sound increased, however, and possibly indicated the presence of numerous microbubbles.

Decompression↗
PubMed1983

Decompression sickness: USAF experience 1970-80.

During the period 1970-80, there were 58 cases of decompression sickness in one of its forms reported in USAF aircrewmen. These cases occurred in a number of different types of aircraft in which cabin/cockpit depressurization occurred either intentionally (because of operational requirements) or because of mechanical malfunction. The most common manifestation of decompression sickness was bends, although some airmen experienced various degrees of neurological dysfunction. Even though none of the aircraft was lost or damaged due to crew incapacitation, the threat was clearly there. The authors briefly review decompression sickness including prevention, treatment, and aeromedical disposition.

Adult↗
PubMedDate not supplied

[Effect of endogenous factors on the process of gas bubble formation in the body in decompression].

Animal experiments were carried out to study the effects of a feeding regimen and diet composition on the intensity of post-decompression bubble formation as well as to establish a correlation between this process and previous decompression, increased and decreased muscle work, and physico-chemical and morphological blood parameters. There was a correlation between the rate of bubble formation during decompression and the above factors.

Animals↗
PubMed1982

Aseptic necrosis in compressed air tunnel workers using current OSHA decompression schedules.

Aseptic necrosis (dysbaric osteonecrosis) was discovered in two compressed air tunnel workers who had used the present Occupational Health and Safety Administration (OSHA) decompression tables for compressed air tunneling at pressures greater than 36 pounds per square inch gauge (psig). A roentgenographic study was made of 21 men who had worked at pressures up to 43 psig using the OSHA schedules. Bone scanning was also included. Seven of the men (33%) were found to have aseptic necrosis involving the shoulders, hips or distal femoral shafts and proximal tibia. It became evident that the present OSHA schedules caused not only an unacceptable incidence of decompression sickness but also aseptic necrosis at pressures over 36 psig. New interim tables that are more conservative and that use either air or oxygen as a breathing gas during decompression are undergoing laboratory and worksite evaluation.

Adult↗