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PubMed2003

Management of isthmic spondylolisthesis with posterolateral endoscopic foraminal decompression.

STUDY DESIGN: Prospective evaluation of 24 consecutive patients with isthmic spondylolisthesis with chronic back, buttock, and leg pain treated by endoscopic foraminal decompression and followed for a minimum of 2 years. OBJECTIVES: To assess the efficacy of endoscopic foraminal decompression and mobilization of the exiting and transiting nerves, discectomy, ablation of osteophytes, and impinging pars as a means of treatment by the posterolateral approach. SUMMARY OF BACKGROUND DATA: Open decompression with or without fusion is a commonly accepted procedure for symptomatic isthmic spondylolytic spondylolisthesis in patients who fail to respond to conservative treatment. There is no published data on the outcome of endoscopic procedures for this condition. METHODS: Endoscopic foraminal decompression achieved with laser-assisted bone and soft-tissue ablation was performed on 12 males and 12 females with an average age of 42.4 years (36-72 years) followed for an average period of 34 months (28-46 months). The average preoperative duration of symptoms was 6.1 years (3-9 years). RESULTS: One hundred percent cohort integrity was maintained at the final follow-up. Results were analyzed using the percentage change in Oswestry Disability Scores and in Visual Analogue Pain scores. Using a percentage change in Oswestry Disability Score of 50 or more plus VAP scores of 50 or more to determine good and excellent outcomes, 79% (19 out of 24) exceeded this value. CONCLUSION: Laser-assisted endoscopic foraminal decompression provides a minimalist means of exploring the extraforaminal zone, the isthmic defect, the foramen and its contents, the disc and the epidural space. It allows adequate resection with decompression and discectomy, without the need for open decompression and fusion, and targets the symptomatic level effectively in patients with Grade I-III isthmic spondylolisthesis.

Adult↗

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↗

PubMed2003

Improvement in brainstem auditory evoked potentials after suboccipital decompression in patients with chiari I malformations.

OBJECT: The optimal treatment for patients with symptoms related to Chiari I malformation remains controversial. Although a suboccipital decompression with duraplasty is most commonly performed, there may be a subset of patients who improve in response to bone decompression alone. In an initial attempt to identify such patients, we performed a continuous study of intraoperative brainstem auditory evoked potentials (BAEPs) in patients undergoing a standard decompression with duraplasty and compared conduction times at three different time points: 1) baseline while the patient is supine (before positioning); 2) immediately after opening of the bone and release of the atlantooccipital membrane (that is, the dural band); and 3) after opening of the dura mater. METHODS: Eleven children and young adults (mean age 9.8 years) with symptoms related to Chiari I malformation underwent suboccipital decompression and duraplasty with intraoperative monitoring of BAEPs and somatosensory evoked potentials (SSEPs). Six patients (55%) had associated syringomyelia. At baseline, the I to V interpeak latency (IPL) for both sides (total 21 BAEPs) was 4.19 +/- 0.22 msec (mean +/- standard deviation). After complete bone decompression and before the dura mater was opened, the I to V IPL decreased to 4.03 +/- 0.25 msec (p = 0.0005). When the dura was opened, however, no further decrease in the I to V IPL was detected (4.03 +/- 0.25 msec; p = 0.6). The SSEPs remained stable throughout the procedure. CONCLUSIONS: In children and young adults undergoing suboccipital decompression with duraplasty for Chiari I malformation, the vast majority of improvement in conduction through the brainstem occurs after bone decompressionand division of the atlantooccipital membrane, rather than after opening of the dura. Additional studies are needed to establish whether the improvement seen with BAEP monitoring during bone decompression will predict long-term clinical improvement in these patients.

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↗

PubMedDate not supplied

[Transoral decompression of the brain stem in a basilar impression secondary to rheumatoid arthritis. Description of a case and survey of the literature].

INTRODUCTION: The vertical subluxation or translocation of the odontoid process producing a basilar impression with compression of the brain stem is a late phenomenon in the course of rheumatoid arthritis; the appearance of symptoms in the spinal cord and the lower pairs of spinal nerves is a specific sign of this disorder. In this situation, the standard surgical aims are the decompression of the affected nerve structures followed by craniocervical stabilisation. The objective of this paper is to report on the improvement of the neurological deficit after decompressive transoral surgery (odontoidectomy), without associating any internal fixation system, in a female patient with a long history of rheumatoid arthritis and anterior compression of the brain stem caused by basilar impression and rheumatoid pannus. A survey of the literature showed that, with the odd isolated clinical case, there are no papers which describe the post operative development of surgical decompression of the brain stem carried out through an anterior approach in patients with rheumatoid subluxation of the odontoid process, without associating any internal stabilisation system. CASE REPORT: Female aged 65, diagnosed as suffering from rheumatoid arthritis at the age of 25, who was admitted with symptoms of compression of the medulla oblongata secondary to a vertical subluxation of the odontoid process. She was submitted to transoral decompression of the brain stem (odontoidectomy and removal of pannus without posterior fixation), and made surprisingly favourable post operative progress. At 15 months after the surgical decompression she led an independent life. CONCLUSIONS: The neurological improvement of our patient after the decompressive odontoidectomy suggests that the mechanical compression of the odontoid process with impaction of the brain stem was the predominant aetiological factor causing the symptoms in the medulla oblongata. Her clinical stabilisation, on the other hand, can be explained by a mechanism involving the spontaneous autofusion of the lateral masses of the atlas with the occipital condyle and with the axis. Lastly, we consider that, in certain cases of rheumatoid patients with atlantoaxial subluxation, impaction of the odontoid process in the foramen magnum and clinical features involving compression of the medulla oblongata, transoral decompression of the brain stem through an odontoidectomy is the choice initial surgical procedure, since it affords neurological improvement and clinical stabilisation. In any case, a strict neurological and radiological post operative follow up is needed in view of a possible craniocervical fixation occurring in the future.

Aged↗

PubMed2003

[Observation of clinical results of orbital decompression in 30 cases of malignant exophthalmos].

OBJECTIVE: To evaluate the effectiveness and safety of orbital decompression for the treatment of malignant exophthalmos. METHODS: Thirty four eyes of malignant exophthalmos were followed-up for 3 months to 9 years (averaged 6 years) after orbital decompression (two walls decompression in 22 eyes, three walls decompression in 12 eyes). The postoperative vision, protrusion value and appearance of the patients were examined and analyzed. RESULTS: Complete closure of palpebral fissure was attained in all cases and the visual acuity was increased in 25 eyes, remained the same in 5 eyes and decreased in 4 eyes. The mean recession of exophthalmos after operation was 3.8 mm in two walls decompression and 7.1 mm in three walls decompression, respectively. CONCLUSION: Orbital decompression is an effective method for the treatment of malignant exophthalmos.

Adult↗

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↗