SEARCH · PubMed Health

Results for “Decompression”

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 145 records · Page 8Linked to original sources

PubMed2002

Immediate spinal cord decompression for cervical spinal cord injury: feasibility and outcome.

BACKGROUND: The effect of immediate surgical spinal cord decompression on neurologic outcome after spinal cord injury is controversial. Experimental models strongly suggest a beneficial effect of early decompression but there is little supportive clinical evidence. This study is designed to evaluate the feasibility and outcome of an immediate spinal cord decompression treatment protocol for cervical spinal cord injury in a tertiary treatment center. METHODS: To address this issue, 91 consecutive patients with acute, traumatic cervical spinal cord injury (1990-1997) were prospectively studied. Sixty-six patients (protocol group) underwent emergency magnetic resonance imaging (MRI) to determine the presence of persistent spinal cord compression followed, if indicated, by immediate operative decompression and stabilization. Twenty-five patients were managed outside the treatment protocol because of contraindication to magnetic resonance imaging, need for other emergency surgical procedures, or admitting surgeon preference (reference group). The protocol and reference groups had similar sex and age distributions, admitting Frankel grades, levels of neurologic injury, and Injury Severity Scores. RESULTS: Twenty-seven percent of patients seen were not enrolled in the treatment protocol because of the need for other emergent surgical treatment, contraindication to MRI, and specific surgeon bias regarding the "futility" of emergent treatment. The neurologic outcome for the patients in the reference group were similar to that in the previously reported literature. Fifty percent of protocol patients, compared with only 24% of reference patients, improved from their admitting Frankel grade. Eight protocol patients (12%), but no reference patients, improved from complete motor quadriplegia (Frankel grade A or B) to independent ambulation (Frankel grade D or E). Protocol patients required shorter intensive care unit stays, and shorter total hospital stays than reference patients. In the treatment protocol group, spinal cord decompression, confirmed by MRI, was achieved with immediate spinal column alignment and skeletal traction in 32 patients (46%). Thirty-four patients (54%) required emergent operative spinal cord decompression because of MRI-documented persistent spinal cord compression. CONCLUSION: We conclude that immediate spinal column stabilization and spinal cord decompression, based on magnetic resonance imaging, may significantly improve neurologic outcome. The feasibility of such a treatment protocol in a tertiary treatment center is well demonstrated. Additional multicenter trials are necessary to achieve definitive conclusions regarding clinical efficacy.

Adolescent↗

PubMed1999

The degree of decompressive relief and its relation to clinical outcome in patients undergoing surgery for lumbar spinal stenosis.

STUDY DESIGN: A cross-sectional, clinical study to evaluate surgical decompression of the stenotic area monitored by computed tomographic scan and its relation to clinical variables in patients operated on for lumbar spinal stenosis. OBJECTIVE: To study in patients with lumbar spinal stenosis the influence of the degree of compressive relief on the patients' clinical outcome. SUMMARY OF BACKGROUND DATA: The goal of surgical treatment in lumbar spinal stenosis is to decompress the stenotic area. Although the decompression should be adequate, there are no clear guidelines to determine the extent of necessary decompression. In fact, there is clinical evidence that there is a discrepancy between the surgical outcome in the patient with lumbar spinal stenosis and postoperative radiologic findings. METHODS: In 92 patients with lumbar spinal stenosis who had had no prior back surgery, preoperative and postoperative computed tomographic scans were obtained to determine the degree of decompression. The postoperative scan findings were classified according to the degree of decompression into a no-stenosis group (n = 35), an adjacent-stenosis group (n = 27), and a residual-stenosis group (n = 30). The postoperative instability of the lumbar spine was investigated by functional radiography. The subjective disability of the patients was assessed using the Oswestry score and the severity of pain using the visual analog scale. Walking capacity was evaluated by a treadmill test. The patients' estimations of the results of surgery were classified into groups of satisfied patients and dissatisfied patients. RESULTS: The mean Oswestry score in all 92 patients was 27.1, and mean walking capacity was 630 m. In the satisfied patients, the Oswestry score was 18.8 and in the dissatisfied patients, 34.9 (P < 0.0000). Walking capacity was 690 m and 594 m, respectively. There were 30 patients with postoperative spinal instability, but it had no influence on surgical outcome. There were no differences in the Oswestry score, walking capacity, and patients' satisfaction among the postoperative CT groups. In the linear regression analysis, the satisfied patient corresponded significantly with the Oswestry score. CONCLUSIONS: The satisfaction of the patients with the results of surgery was more important in surgical outcome than the degree of decompression detected on computed tomographic scan.

Cross-Sectional Studies↗

PubMed1999

Effect of decompression enlargement laminoplasty for posterior shifting of the spinal cord.

STUDY DESIGN: A study to measure the shifts of the spinal cords and the effects of decompression laminoplasty in 65 patients with cervical lesions who underwent computed tomographic myelography before and after laminoplasty. OBJECTIVES: To investigate limitations of the spinal cord posterior shift after laminoplasty and to clarify the optimal decompression areas to obtain effective posterior shifting. SUMMARY OF BACKGROUND: Although several types of laminoplasty have been performed, all procedures share the common purpose of posterior decompression. No previous studies have examined the limitations of posterior decompression or the optimal decompression range. METHODS: The distance from the posterior edge of each vertebral body or disc level to the posterior edge of the spinal cord was measured by computed tomographic myelography. After the posterior shift was determined by calculating the difference between pre- and postsurgical distances, the relations between posterior shift and neck alignment, clinical results, and the areas of decompression were analyzed. RESULTS: The spinal cord shift ranged from a maximum of 6.6 mm to a minimum of 0 mm. Clinically, spinal cord shifts greater than 3 mm were associated with good clinical outcomes. Upward or downward advanced laminoplasty was related to larger spinal cord shifts at the upper or lower cervical spine. CONCLUSIONS: A mean spinal cord shift of > 3 mm was associated with good clinical outcomes after laminoplasty. In cases with compressive lesions at the upper or lower cervical spine, extension of decompression one level above or one level below likely results in a greater posterior spinal cord shift at these lesions.

Cervical Vertebrae↗

PubMed1997

Decompression comparison of helium and hydrogen in rats.

The hypothesis that there are differences in decompression risk between He and H2 was examined in 1,607 unanesthetized male albino rats subjected to dives on 2% O2-balance He or 2% O2-balance H2 (depths < or = 50 ATA, bottom times < or = 60 min). The animals were decompressed to 10.8 ATA with profiles varying from rapid to slow, with up to four decompression stops of up to 60 min each. Maximum likelihood analysis was used to estimate the relative decompression risk on a per unit pressure basis (termed "potency") and the rate of gas uptake and elimination, both factors affecting the decompression sickness risk, from a specific dive profile. H2 potency for causing decompression sickness was found to be up to 35% greater than that for He. Uptake rates were unresolvable between the two gases with the time constant (TC) estimated at approximately 2-3 min, leading to saturation in both cases in < 15 min. Washout of both gases was significantly slower than uptake, with He washout (TC approximately 1.5-3 h) substantially slower than H2 washout (TC approximately 0.5 h). It is unknown whether the decompression advantage of the faster washout of H2 or the disadvantage of its increased potency, observed in the rat, would be important for human diving.

Animals↗

PubMed2002

Gas bubbles in rats after heliox saturation and different decompression steps and rates.

Effects of pressure reduction, decompression rate, and repeated exposure on venous gas bubble formation were determined in five groups (GI, GII, GIII, GIV, and GV) of conscious and freely moving rats in a heliox atmosphere. Bubbles were recorded with a Doppler ultrasound probe implanted around the inferior caval vein. Rats were held for 16 h at 0.4 MPa (GI), 0.5 MPa (GII and GIII), 1.7 MPa (GIVa), or 1.9 MPa (GIV and GV), followed by decompression to 0.1 MPa in GI to GIII and to 1.1 MPa in GIV and GV. A greater decompression step, but at the same rate (GII vs. GI and GIVb vs. GIVa), resulted in significantly more bubbles (P < 0.01). A twofold decompression step resulted in equal amount of bubbles when decompressing to 1.1 MPa compared with 0.1 MPa. The faster decompression in GII and GVa (10.0 kPa/s) resulted in significantly more bubbles (P < 0.01) compared with GIII and GVb (2.2 kPa/s). No significant difference was observed in cumulative bubble score when comparing first and second exposure. With the present animal model, different decompression regimes may be evaluated.

Adaptation, Physiological↗

PubMed2002

Endoscopic orbital decompression for Graves' ophthalmopathy.

Graves' disease may occasionally result in significant proptosis that is either cosmetically unacceptable or causes visual loss. This has traditionally been managed surgically by external decompression of the orbital bony skeleton. Trans-nasal endoscopic orbital decompression is emerging as a new minimally-invasive technique, that avoids the need for cutaneous or gingival incisions. Decompression of the medial orbital wall can be performed up to the anterior wall of the sphenoid sinus. This can be combined with resection of the medial and posterior portion of the orbital floor (preserving the infra-orbital nerve). This technique produces decompression which is comparable to external techniques. We present a series of 10 endoscopic orbital decompressions with an average improvement of 4.4 mm in orbital proptosis. There was an improvement in visual acuity in all patients with visual impairment. Endoscopic orbital decompression is recommended as an alternative to traditional decompression techniques.

Decompression, Surgical↗

PubMed2001

Effects of intraluminal distention and decompression on microvascular permeability and hemodynamics of the equine jejunum.

OBJECTIVE: To determine whether intraluminal distention and subsequent decompression of the equine jejunum affects intestinal blood flow, hemodynamics, and microvascular permeability. ANIMALS: 5 healthy adu t horses. PROCEDURES: Horses were anesthestized and underwent exploratory laparotomy. Two jejunal segments were identified as sham-operated or instrumented segments. After baseline values were obtained, intraluminal distention was created in the experimental segment to induce an ntraluminal pressure of 18 cm H2O. After 120 minutes of distention, the intestine was decompressed for 120 minutes. Mesenteric blood flow, oxygen delivery, oxygen consumption, microvascular permeability, wet weight-to-dry weight ratio, neutrophil infiltration, and vascular resistance were determined and comparisons made among control, sham-operated, and experimental segments. RESULTS: Mean jejunal blood flow was 21.4 ml/min per kg. There was a significant decrease in mesenteric bood flow to the distended intestine (13.4 ml/min per kg). Blood flow increased significantly during the decompression period (340% of baseline blood flow). Intraluminal distention and subsequent decompression resulted in a significant increase in microvascular permeability, as determined by the osmotic reflection coefficient. Oxygen delivery and oxygen content decreased significantly during the distention period and increased during decompression. Morphologic evaluation revealed a significant increase in edema and neutrophil infiltration after distention and decompression, compared with results for the sham-operated or control segments. CONCLUSIONS AND CLINICAL RELEVANCE: Intraluminal distention and decompression of the equine jejunum results in low-flow ischemia and edema, which may contribute to adhesions and ileus in the postoperative period after surgery for obstructions of the small intestines.

Animals↗

PubMed1999

Ventricular pressure monitoring during bilateral decompression with dural expansion.

OBJECT: The management of massive brain swelling remains an unsolved problem in neurosurgery. Despite newly developed medical and pharmacological therapy, the rates of mortality and morbidity caused by massive brain swelling remain high. According to many recent reports, surgical decompression with dural expansion is superior to medical management in patients with massive brain swelling. To show the quantitative effect of decompressive surgery on intracranial pressure (ICP), the authors performed a ventricular puncture and measured the ventricular ICP continuously during decompressive surgery and the postoperative period. METHODS: Twenty patients with massive brain swelling who underwent bilateral decompressive craniectomy with dural expansion were included in this study. In all patients, ventricular puncture was performed at Kocher's point on the side opposite the massive brain swelling. The ventricular puncture tube was connected to the continuous monitor via a transducer device. The ventricular pressure was monitored continuously, during the bilateral decompressive procedures and postoperative period. The initial ventricular ICP was variable, ranging from 16 to 65.8 mm Hg. Immediately after the bilateral craniectomy, the mean ventricular ICP decreased to 50.2+/-16.6% of the initial ICP (range 5-51.5 mm Hg). Additional opening of the dura decreased the mean ICP by an additional 34.5% and reduced the ventricular pressure to 15.7+/-10.7% of the initial pressure (range 0-15 mm Hg). Ventricular pressure measured postoperatively in the neurosurgical intensive care unit was lowered to 15.1+/-16.5% of the initial ICP. The ventricular ICP trend in the first 24 hours after decompressive surgery was an important prognostic factor; if it was greater than 35 mm Hg, the mortality rate was 100%. CONCLUSIONS: Bilateral decompression with dural expansion is an effective therapeutic modality in the control of ICP. To obtain favorable clinical outcomes in patients with massive brain swelling, early decision making and proper patient selection are very important.

Adolescent↗

PubMedDate not supplied

Study of long intestinal tube for decompression of obstructive left colon cancer.

BACKGROUND/AIMS: Recently, several reports have recommended primary resection, rather than a staged operation, for obstructive left colon cancer. However pre-operative decompression is important for reducing complications and improving the curability of primary resection. Among the many pre-operative decompression strategies reported, we selected the long intestinal tube and evaluated the effectiveness of this convenient strategy. METHODOLOGY: A long intestinal tube was inserted pre-operatively for decompression in 27 of 29 patients undergoing resection for obstructive left colon cancer (1991-1995). We retrospectively studied the clinical features (responders vs. non-responders) of the 27 patients. We also compared these 27 with 26 other pre-1990 patients, who did not receive pre-operative decompression, in term of post-operative morbidity. RESULTS: Twelve of the 27 patients were responders; success rate 44.4%. There were no blood profile differences between responders and non-responders, but the time from bowel movement cessation to intestinal tube insertion was 3 days or less in all responders but 4 days or more in non-responders (p<0.001). There was no significant difference in the rate of post-operative morbidity between those with and without pre-operative decompression. CONCLUSIONS: Decompression is likely to be successful, allowing elective primary resection, when initiated within 3 days of bowel movement cessation. However, more than 4 days post-onset, other decompression methods or emergency surgery is necessary.

Adenocarcinoma↗

PubMed1976

Decompression-induced bubble formation in salmonids: comparison to gas bubble disease.

The relationship of gas bubble disease (GBD) in fish to decompression-induced bubble formation was investigated with salmonids. Acute bioassays were used to determine equilibration times for critical effects in fish decompressed from depths to 200 fsw. It was found that equilibration of critical tissues was complete in 60-90 min. Salmonids and air-breathers are sensitive to decompressions at similar levels of supersaturation if elimination of excess gas following decompression is unrestricted. However, if elimination is restricted, bubble formation and growth increase accordingly. Tests with mixtures of He-O2, Ar-O2, N2-O2 (80% inert gas: 20% O2) and pure oxygen demonstrated that gas solubility as well as supersaturation (delta P), pressure ratio (initial pressure: final pressure), and absolute pressure must be considered in setting tolerance limits for any decompression. Gases with higher solubility are more likely to produce bubbles upon decompression. Oxygen, however, does not follow this relationship until higher pressures are reached, probably owing to its function in metabolism and in binding with hemoglobin. Tissue responses observed in both GBD and decompressed fish involved similar pathological effects at acute exposures. The circulatory system was consistently affected by bubbles that occluded vessels and blocked flow through the heart.

Animals↗

PubMed2000

Preliminary report: long-term results of transnasal orbital decompression in malignant Graves' ophthalmopathy.

In order to demonstrate the safety and efficacy of transnasal orbital decompression for malignant Graves' ophthalmopathy, we carried out a retrospective chart review and clinical follow-up examination of 78 consecutive patients who were operated on for compressive optic neuropathy (CON) with loss of visual acuity or visual field defects. The intervention - strictly transnasal, endoscopically controlled, bilateral decompression of the medial and inferomedial wall of the orbit - was performed when medical and radiation therapy had failed. A total of 145 endonasal decompressions were performed on 78 patients (63 female, 15 male, 52. 2 +/- 10.5 yrs.) over 9 years. Of these, 65 were operated bilaterally, 15 required only unilateral decompression; 4 had repeated surgery. Visual acuity increased from an average of 0.50 +/- 0.27 (range, 0.01 - 1.25) to 0.75 +/- 0.21 (range, 0.01 - 1.25). Proptosis decreased by an average of 3.94 +/- 2.73 mm (range, -1.0 - 11.0 mm), from a mean preoperative Hertel measurement of 22.19 +/- 3. 13 mm (range, 15 - 34 mm) to a mean postoperative Hertel measurement of 18.3 +/- 2.65 mm (range, 10 - 26 mm). Ocular motility was corrected by recession of the medial rectus muscle in 58 cases, in 26 cases immediately after decompression in the same surgical session. The transnasal orbital decompression procedure improved vision, decreased proptosis in a range comparable to more invasive techniques and had favorable cosmetic results without additional disfiguring by scars. Post-decompression strabismus was successfully managed by recession of both medial orbital muscles in the same surgical session.

Decompression, Surgical↗

PubMed2000

Computation of decompression tables using continuous compartment half-lives.

There is no consensus on the number of compartments and the half-lives (T1/2) used in the calculation of inert gas exchange and decompression sickness (DCS) boundary in existing dive tables and decompression computers. We propose the use of a continuous variable for the tissue half-lives, allowing the simulation of an infinite number of compartments and reducing the discrepancy between different algorithms to a single DCS boundary expression. Our computational method is based on the premise that M-values can be expressed in terms of T1/2 and ambient pressure (D). We combined the surfaces defined by M(D,T1/2) and tissue tension H(t,T1/2) to plan decompression. The efficiency and applicability of the method is investigated with four different DCS boundaries. The first two utilize the M-value relations proposed by Bühlmann and Wienke to derive no-D limits for sea level. The third boundary is defined by a surface fitted to the empirical M-values of US Navy, Bühlmann tables, US Air Force, and our altitude diving data. This expression was used to design the decompression procedure for a multilevel dive at 11,429-ft altitude and was used in six man dives in the Kaçkar Mountains, Turkey. Although precordial bubbles were observed in two dives, there were no cases of DCS. The fourth DCS boundary is constructed with the addition of a constraint that forces calculated M-values to stay below the available M-values. This constraint aims the highest degree of "conservatism". As an application of the new boundary, the method is used to derive decompression stop diving schedules for 11,429-ft altitude. The concept of continuous tissue half-lives is applicable to different types of gas exchange and DCS boundary functions or to a combination of different models with a desired level of conservatism. It has proved to be a useful tool in planning decompression for undocumented modes of diving such as decompression stop diving or multilevel diving at altitude. The algorithm can easily be incorporated into dive computers.

Algorithms↗

PubMed2001

[Results of arthroscopic subacromial decompression in 50-year-old patients].

PURPOSE OF THE STUDY: The study presents results of the surgical treatment of subacromial impingement syndrome in patients between fifty and sixty years of age using the technique of a two-step arthroscopic subacromial decompression. MATERIAL: Arthroscopic subacromial decompression was used for the operation on 12 shoulders in 12 patients. All of them underwent minimally half a year of conservative treatment. The average age of patients at the time of operation was 51 years. The youngest was 43 years, the remaining patients were older than 49 years. Only in 4 patients the subacromial impingement was not associated with another diagnosis. The group included also 2 patients with an associated diagnosis which resulted in the failure of arthroscopic technique. The follow-up ranges between 6 to 22 months. METHODS: The applied technique of arthroscopics subacromial decompression has two phases. Distal acromioplasty uses the dorsal edge of the acromion as a cutting block necessary for smoothing its inferior surface: By anterior acromioplasty was removed the anterior part of lateral clavicle prominent to the anterior edge of acromion. Part of the technique is resection of the accessible portion of the coracoacromial ligament. The difference between systolic pressure of the patient and the pressure in the subacromial space above 50 mm Hg significantly reduces bleeding. The precision of the technique is supported by a careful preoperative planning of the extent of resection on special x-ray projections. Strict observation of the schedule of postoperative physiotherapy is a necessary precondition of a successful result. The result of arthroscopic subacromial decompression is evaluated on the basis of UCLA score which allows comparison with the groups of patients of other authors. RESULTS: Using UCLA score the group of patients operated on included 3 excellent, 4 good, 3 satisfactory and 2 poor results. The first failure was recorded in a 50-year old man with a finding of a massive rupture of the rotator cuff and with an associated diagnosis of the fracture of clavicle healed in dislocation. After 6 months open acromioplasty and reconstruction of the rotator cuff was performed in this patient. Another poor result was recorded in a 57-year old female patient with an associated diagnosis of tendinitis calcarea of m. supraspinatus which was caused by the failure to remove calcification and insufficient extent of the resection of acromion. After the interval of 3 months also here open acromioplasty was performed. Ten out of twelve patients are satisfied and do not require another treatment. It means that also three satisfactory results (according to UCLA score) mean a marked pain relief and improvement of the function of the shoulder of not very active 50-year old individuals. DISCUSSION: Other authors report the frequency of good and excellent results they achieved in the range of 73-94%. Objectively evaluated arthroscopic subacromial decompression in our group of patients is not so successful as the operation performed in younger age groups. However, the subjective evaluation of the operation is very favourable. This satisfaction results from realistic expectations of patients who were not active sportsmen. In young patients active in sport with a primary subacromial impingement syndrome the arthroscopic method is a gold standard method. It is a mistake not to indicate the reconstruction of the ruptured rotator cuff in active patients under the age of 50. In the sixth decade, however, no outstanding results can be expected of it. Therefore in this group a precisely performed arthroscopic subacromial decompression has a very favourable effect mainly due to a shorter time of physiotherapy. CONCLUSION: The success of arthroscopic subacromial decompression is conditioned by a careful indication of the type of surgery, preoperative planning, precise technique of the actual operation and a strict observation of individual steps of postoperative physiotherapy of the shoulder. The operation may significantly relieve the pain and improve the function of the shoulder and at the same time it does not weaken the acromial origin of the m. deltoideus. It reduces the time of recovery and reduces also the risk of arthrofibrosis which endangers mainly older less active patients.

Acromion↗

PubMed1989

Decompression: English tables.

The formulation of decompression procedures has generally been based on the observation that divers can be decompressed without stoppages to surface, from steady-state exposures of about twice the atmospheric pressure. Because decompression sickness rarely develops from this "no-stop decompression", it has been assumed that no gas is liberated. It is therefore assumed, in the calculation of the majority of decompression tables, that using a 2:1 decompression ratio allows the additional gas load from the hyperbaric exposure to be transported to the lungs in solution. Ultrasonic scanning and Doppler techniques have shown that this is not the case. Decompression tables must therefore be formulated so as to take into account the presence of gas, the critical diameter of circulating bubbles and the inherent unsaturation introduced by oxygen.

Decompression↗

PubMed1986

An effect of CO2 on the maximum safe direct decompression to 1 bar from oxygen-nitrogen saturation.

An investigation into the maximum safe decompression step from oxygen nitrogen saturation to 1 bar was carried out with and without the presence of 0.02 bar carbon dioxide. The series, Islander 1, involved 13 teams of 5, fully informed, male volunteers carrying out simulated dives. One group of 6 teams carried out dives in an atmosphere of 0.4 bar oxygen, balance nitrogen (O2-N2); another group of 7 teams used an atmosphere of 0.38 bar oxygen, 0.02 bar carbon dioxide, balance nitrogen (O2-N2-CO2). The dives consisted of a 48-h stay at 1.7 or 1.8 bar to saturate the tissues, followed by decompression to 1 bar air at 0.5 bar/min. Two decompression parameters were studied; the incidence of decompression sickness (DCS) in the 24 h postdecompression, and the incidence and grade of venous gas emboli (VGE) in the first 6 h postdecompression. The grade of VGE was assessed using the Kisman-Masurel scoring system which produces a bubble grade with the subject at rest and after movement. No significant difference was found in the incidence of DCS between the two groups. Twenty subjects were decompressed from 1.7 bar using each mixture, without signs or symptoms of DCS. However, after decompression from 1.8 bar there were 2 cases of DCS in 10 subjects in the O2-N2 group and 2 cases in 15 subjects in the O2-N2-CO2 group. The incidence of detectable VGE was always lower in the O2-N2-CO2 group at both saturation pressures; at 1.7 bar the VGE incidence was lower by 40% (P less than 0.05) at rest and by 55% (P less than 0.001) after movement. At 1.8 bar the reduction was 3% (NS) at rest and 30% (NS) after movement. The results indicate that decompression from 1.8 bar to 1 bar, with or without the presence of 0.02 bar carbon dioxide, is likely to produce more than 5% DCS.

Adult↗

PubMed1983

Hyperbaric exposure during pregnancy in sheep: staged and rapid decompression.

Hyperbaric exposure during pregnancy in sheep: staged and rapid decompression. Undersea Biomed Res 1983; 10(1): 11-15. --Twelve sheep with dated pregnancies were exposed for 20 min to hyperbaric pressure comparable to 165 feet of sea water weekly between the 49th and 133rd days of pregnancy. Six were decompressed in stages and six directly without decompression stops. Those that were decompressed gradually delivered normally at or near term. One lamb was abnormal, but the relationship to pressurization is unclear. Three of those decompressed rapidly aborted dead fetuses, and two others delivered mature, but affected, lambs. Under the conditions of this study staged decompression after repeated hyperbaric exposures protected the fetuses from the destructive effects of rapid decompression. Hyperbaric pressure did not alter gross anatomic development.

Abortion, Incomplete↗

PubMed1997

Reversibility in blood-brain barrier, microcirculation, and histology in rat brain after decompression.

To examine the changes in blood-brain barrier (BBB), cerebral microcirculation, and histology from 15 min to 72 h after decompression, 90 rats were exposed to experimental compression to 6 atm abs air for 90 min and subsequent rapid decompression. The disruption of BBB was examined by Evans blue extravasation. The cerebral microcirculation was demonstrated by perfusion with India ink. The area stained with Evans blue and the regions of defective filling with India ink, observed immediately after decompression decreased in size with time and were undetectable 3-24 h after decompression. The edematous brain tissue with enlarged perivascular space and darkly stained nerve cells also decreased to the uncompressed control level 1-24 h after decompression. These reversible dysbaric changes, however, reappeared 48-72 h after decompression. The different mechanisms, the physicochemical effects of microbubbles, and the maturation phenomenon after temporary brain ischemia induced by dysbaric microbubbles may be involved in the brain damage after decompression sickness.

Animals↗

PubMed1998

[Follow-up monitoring with magnetic resonance tomography after decompressive trephining in experimental "malignant" hemispheric infarct].

Acute ischemia in the complete territory of the carotid or the middle cerebral artery may lead to cerebral edema with raised intracranial pressure and progression to coma and death. Although clinical data suggest benefit for patients undergoing decompressive surgery for massive space occupying hemispheric stroke, little data about the effects of this procedure on morbidity and outcome is available. The experimental data support an early surgical approach. For early and probably most effective treatment of severe, space-occupying cerebral ischemia, the "malignant" character of the brain edema has to be recognized early after onset of vessel occlusion. Hereby magnetic resonance imaging (MRI) may allow to determine the clinical significance of brain edema early after onset, simultaneously allowing to monitor the evolution of ischemia. We performed serial SE-MRI in rats with acute hemispheric infarctions treated by decompressive craniectomy. Focal cerebral ischemia was induced in 36 rats using an endovascular occlusion technique. Decompressive craniectomy was performed 4 and 24 hours after vessel occlusion in groups of 12 animals each. Twelve animals were not treated by decompressive craniectomy (control group). Four, 24, 48, 72 and 168 hours after MCAO all animals were examined with conventional T1- and T2-weighted SE-MRI. Shift of the midline structures and compression of the ventricles were scored. Changes in weight and neurological performance were measured daily. The infarction volume was calculated by triphenyltetrazolium chloride staining 168 hours after MCAO. While mortality in the untreated group was 33.3%, none of the animals treated by a decompressive craniectomy died (mortality 0%). Neurological behaviour, weight loss and infarction volume were significantly better in the animals treated by early decompressive craniectomy (p < 0.05). Four hours after MCAO all untreated animals showed a massive shift of the midline structures and a massive compression of the ventricles; only 7 of 12 animals treated early by craniectomy showed mild mass effects. Correlation of the histological brain damage with T2-weighted MRI 4 hours after MCAO was poor (r = 0.41); later than 24 hours there was a good correlation (r > 0.7). Our results suggest that decompressive craniectomy in malignant cerebral ischemia reduces mortality and significantly improves outcome. If performed early after vessel occlusion, it also significantly reduces infarction size. In the acute phase of hemispheric infarction conventional SE-MRI is not sensitive in estimation of infarction size. Later than 24 hours, conventinal SE-MRI proved to be useful in monitoring brain edema and infarction size in this rat model of malignant hemispheric stroke.

Animals↗