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At least 379 records · Page 21Linked to original sources
PubMed1997

Incidence of postlaminectomy kyphosis after Chiari decompression.

STUDY DESIGN: In this retrospective study, a 5-year series of a pediatric population undergoing Chiari decompressions is reviewed. OBJECTIVES: To review the experience with children treated with suboccipital craniectomy and uni- or multilevel cervical laminectomy for Chiari malformation, to determine the incidence of kyphosis and to identify factors predictive of cervical instability. SUMMARY OF BACKGROUND INFORMATION: Upper cervical laminectomy in the pediatric population has a significant risk of postoperative kyphosis. To decrease the incidence of this complication, a concerted effort was made to avoid violation of the facet joint during cervical laminectomy. METHODS: Thirty-two patients (mean age 4.9 years, range 1 day to 18 years) had surgical decompression of Chiari I or II malformations throughout a 5-year period (1989-1994). Radiographs and operative records were analyzed to determine the number of cervical levels decompressed and extent of laminectomy. RESULTS: Mean follow-up was 3.7 years (range 9 months to 7 years). Only one patient had clinical and radiographic evidence of kyphosis and required C2-C3 fusion. Two others had radiographic signs of mild cervical kyphosis but remained asymptomatic. These three patients had two-level complete laminectomies. Twenty-nine patients had no clinical or radiographic evidence of cervical instability. A mean of three cervical levels were decompressed (range 0-4), including partial laminectomies, complete laminectomies, and one osteoplastic laminotomy to drain a lower cervical syrinx. The overall frequency of kyphosis in this series (9%) was substantially lower than in previous reports. Although the number of cervical levels decompressed did not correlate with cervical instability, the one patient with clinical instability had inadvertent violation of the facet joint, suggesting that overaggressive laminectomy may be a critical factor that predisposes patients to postoperative kyphosis. CONCLUSION: Cervical kyphosis after Chiari decompression is a recognized complication of cervical laminectomy in children, the frequency of which may be decreased by careful attention to operative technique.

Adolescent↗
PubMed1995

Active decompression improves the haemodynamic state during cardiopulmonary resuscitation.

OBJECTIVE: To examine whether use of the active compression-decompression device improves the haemodynamics of cardiopulmonary resuscitation compared with those of conventional cardiopulmonary resuscitation. DESIGN: Prospective crossover study. SETTING: The accident and emergency department of a university teaching hospital. PATIENTS: 36 adult patients with non-traumatic, normothermic, out of hospital cardiac arrest. INTERVENTIONS: Cardiopulmonary resuscitation was performed during resuscitation in alternating 3 min cycles of conventional and active compression-decompression cardiopulmonary resuscitation. MAIN OUTCOME MEASURES: The end tidal carbon dioxide (ETCO2), femoral arterial pressure, and acid-base analysis of central venous blood measured during the last 30 s of each 3 minute cardiopulmonary resuscitation cycle. RESULTS: ETCO2 was monitored in 36 patients during conventional and active compression-decompression cardiopulmonary resuscitation. Active compression-decompression cardiopulmonary resuscitation caused a significant increase in ETCO2 (P < 0.0002), indicating improved cardiac output. Arterial pressure measurement was carried out in 10 patients. Systolic pressure was significantly greater with active compression-decompression than conventional cardiopulmonary resuscitation (P < 0.007). Central venous blood was taken for acid-base analysis in 11 patients. There was a significant increase in the central venous hydrogen ion concentration (P = 0.025) with rises in the partial pressures of carbon dioxide and oxygen, suggesting improved venous return. CONCLUSIONS: This study confirms that active compression-decompression cardiopulmonary resuscitation is associated with better haemodynamic status than conventional resuscitation.

Acid-Base Equilibrium↗
PubMed1976

Influence of long-term intermittent exposures to hypoxia on decompression-induced pulmonary haemorrhage.

Healthy male rats were acclimatized by being placed in a decompression chamber at a simulated altitude of 18 000 feet (5486 m) for three hours daily for 84 days. The altitude acclimatized rats paired with unacclimatized rats were rapidly decompressed together. The range of decompression was performed from on atmospheric pressure to an ambient pressure of 30 mmHg in 0-2 seconds. It was found that in control rats, 14 of 20 lung (70%) exhibited pulmonary haemorrhage following rapid decompression. In altitude acclimatized rats, however, only 6 of 20 (30%) revealed decompression-induced haemorrhage. The difference was statistically significant. The present findings indicate that long-term intermittent exposures to hypoxia might increase the resistance of pulmonary tissue to rapid decompression, resulting in a decrease in frequency and severity of pulmonary haemorrhage. The possible mechanism of such a phenomenon is discussed.

Acclimatization↗
PubMed1991

Metabolic alterations in obstructive jaundice: effect of duration of jaundice and bile-duct decompression.

We examined the effect of prolonged bile duct obstruction, and subsequent biliary decompression, on biochemical and metabolic parameters, using a reversible jaundice model in male Fischer 344 rats. The animals were studied after biliary obstruction for varying periods (4 days, one week, and two weeks) and following decompression. They were sacrificed one or two weeks following decompression. All the rats were compared to sham operated, pair-fed, controls. Obstructive jaundice rapidly increased bilirubin, liver enzymes, serum free fatty acid, and triglyceride levels. Glucose levels were significantly decreased in the jaundice rats compared to their pair-fed controls. Only after two weeks of jaundice was significant hypoalbuminemia observed. Following decompression, all biochemical and metabolic values gradually returned to normal levels, except for albumin. Hypoalbuminemia was not reversed within the two-week post-decompression period. The rats jaundiced for two weeks had significantly higher mortality, compared to the other groups. We conclude that prolonged jaundice adversely affects the metabolic capacity of the rats, with albumin concentration being markedly decreased, and that biliary decompression could not reverse completely all the alterations seen with cholestasis, especially following two weeks of bile duct obstruction.

Animals↗
PubMed1993

The effect of biliary decompression on bacterial translocation in jaundiced rats.

Patients with obstructive jaundice are prone to septic complications after biliary tract operations. Restoring bile flow to the intestine may help to decrease the complication rate. The present study is aimed at evaluating the effect of biliary decompression on bacterial translocation in jaundiced rats. Sixty-six male Sprague-Dawley rats were randomly allocated to six groups subjected to common bile duct ligation (CBDL) and transection (groups 2-6) or sham operation (group 1). In groups 1 and 2 the incidence of enteric bacterial translocation was determined 2 weeks after sham operation or CBDL. In groups 3-6, biliary decompression was achieved by performing a choledochoduodenostomy after 2 weeks of biliary decompression. Bacterial translocation was then studied 1, 2, 3 and 5 weeks following biliary decompression. The rate of bacterial translocation to mesenteric lymph nodes in obstructive jaundice was significantly higher as compared with controls and decreased with time to nil three weeks following biliary decompression. The incidence of bacterial translocation was closely correlated (r = 0.844; p = 0.034) with serum alkaline phosphatase activity and seemed to fit with the morphological changes noted in the small intestine. The decrease in bacterial translocation, however, lags behind the recovery of liver function as measured by routine liver function tests and antipyrine clearance. Obstructive jaundice thus promotes bacterial translocation in the rat. Biliary decompression gradually decreases the rate of bacterial translocation.

Animals↗
PubMed1994

Evaluation of standard and active compression-decompression CPR in an acute human model of ventricular fibrillation.

BACKGROUND: The mechanisms that underlie cardiopulmonary resuscitation (CPR) in humans remain controversial and difficult to study. This report describes a new human model to evaluate CPR during the first 1 to 2 minutes after the onset of ventricular fibrillation (VF). With this model, standard CPR was compared with active compression-decompression (ACD) CPR, a method that uses a handheld suction device to actively compress and actively decompress the chest. METHODS AND RESULTS: During routine inductions of VF as part of a transvenous lead cardioverter/defibrillator implantation procedure, CPR was performed in 21 patients if the first defibrillation shock failed and until a successful rescue shock was delivered. Compressions during CPR were performed according to American Heart Association guidelines. For ACD CPR, decompression was performed with up to -30 lbs. Radial arterial and right atrial pressures were measured in all patients. Esophageal pressures, intratracheal pressures, or minute ventilation was measured in the last 13 patients. Application of both CPR techniques increased arterial and right atrial pressures. The mean coronary perfusion pressure was increased throughout the entire CPR cycle with ACD CPR (compression, 21.5 +/- 9.0 mm Hg; decompression, 21.9 +/- 8.7 mm Hg) compared with standard CPR (compression, 17.9 +/- 8.2 mm Hg; decompression, 18.5 +/- 6.9 mm Hg; P < .02 and P < .02, respectively). Ventilation per compression-decompression cycle was 97.3 +/- 65.6 mL with standard CPR and 168.4 +/- 68.6 mL with ACD CPR (n = 7, P < .001). Negative inspiratory pressure was -0.8 +/- 4.8 mm Hg with standard CPR and -11.4 +/- 6.3 mm Hg with ACD CPR (n = 6, P < .04). CONCLUSIONS: Patients undergoing multiple inductions of VF during cardioverter/defibrillator implantation with transvenous leads provide a well-controlled and reproducible model to study the mechanisms of CPR. Using this model, ACD CPR significantly increased arterial blood pressure, coronary perfusion pressure, minute ventilation, and negative inspiratory pressure compared with standard CPR.

Acute Disease↗
PubMed2005

Medical students who decompress during the M-1 year outperform those who fail and repeat it: a study of M-1 students at the University of Illinois College of Medicine at Urbana-Champaign 1988-2000.

BACKGROUND: All medical schools must counsel poor-performing students, address their problems and assist them in developing into competent physicians. The objective of this study was to determine whether students with academic deficiencies in their M-1 year graduate more often, spend less time to complete the curriculum, and need fewer attempts at passing USMLE Step 1 and Step 2 by entering the Decompressed Program prior to failure of the M-1 year than those students who fail the M-1 year and then repeat it. METHOD: The authors reviewed the performance of M-1 students in the Decompressed Program and compared their outcomes to M-1 students who failed and fully repeated the M-1 year. To compare the groups upon admission, t-Tests comparing the Cognitive Index of students and MCAT scores from both groups were performed. Performance of the two groups after matriculation was also analyzed. RESULTS: Decompressed students were 2.1 times more likely to graduate. Decompressed students were 2.5 times more likely to pass USMLE Step 1 on the first attempt than the repeat students. In addition, 46% of those in the decompressed group completed the program in five years compared to 18% of the repeat group. CONCLUSION: Medical students who decompress their M-1 year prior to M-1 year failure outperform those who fail their first year and then repeat it. These findings indicate the need for careful monitoring of M-1 student performance and early intervention and counseling of struggling students.

Control Groups↗
PubMed1993

Modification of reticuloendothelial function by muramyl dipeptide-encapsulated liposomes in jaundiced rats treated with biliary decompression.

Rats with 2 weeks of biliary obstruction, with and without 1 week of concomitant biliary decompression relieving the jaundice, were treated with physiologic saline, free muramyl dipeptide (MDP), placebo liposomes, or liposome-encapsulated MDP. Reticuloendothelial system (RES) function was evaluated by blood clearance of intravenously injected 125I-labelled Escherichia coli. The corrected phagocytic index (alpha) after 1 week of biliary decompression returned to normal levels in animals treated with MDP liposomes, whereas RES function was impaired (P < 0.05) in all other jaundiced and biliary-decompressed groups. In the biliary-decompressed, MDP-liposome-treated group, hepatic uptake of radiolabelled bacteria was significantly higher (P < 0.05) and renal entrapment of bacteria was significantly lower (P < 0.05) than in all other jaundiced and biliary-decompressed groups. We conclude that treatment with MDP liposomes improves the otherwise impaired RES function in rats with biliary obstruction and biliary decompression.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1999

Surgical decompression for traumatic brain swelling: indications and results.

OBJECT: Decompressive craniectomy has been performed since 1977 in patients with traumatic brain injury. The authors assess the efficacy of this treatment and the indications for its use. METHODS: The clinical status of the 57 patients, their computerized tomography (CT) scans, and intracranial pressure (ICP) levels were documented prospectively in a standard protocol. At the beginning of the study, all patients older than 30 years were excluded. As of 1989 patients older than 40 years were excluded until 1991; since that time patients older than 50 years have been excluded. Primary brain or brainstem injury with fully developed bulbar brain syndrome, loss of auditory evoked potentials (AEPs), and/or oscillation flow in a transcranial Doppler ultrasound examination were contraindications to decompressive craniectomy. A positive indication for decompression was given in the case of progressive therapy-resistant intracranial hypertension in correlation with clinical (Glasgow Coma Scale [GCS] score, decerebrate posturing, dilating of pupils) and electrophysiological (electroencephalography, somatosensory evoked potentials, and AEPs) parameters and with findings on CT scans. Unilateral decompressive craniectomy was performed in 31 patients and bilateral craniectomy in 26 patients. In all cases, a wide frontotemporoparietal craniectomy was followed by a dura enlargement covered with temporal muscle fascia. The outcomes of the treatment were surprisingly good. Only 11 patients (19%) died, three of whom died of acute respiratory disease syndrome. Five patients (9%) survived, but remained in a persistent vegetative state; six patients (11%) survived with a severe permanent neurological deficit, and 33 patients (58%) attained social rehabilitation. Two patients (3.5%) did not have a follow-up examination. The GCS score on the 1st day posttrauma and the mean ICP turned out to be the best predictors for a good prognosis. The results demonstrate the importance of decompressive craniectomy in the treatment of traumatic brain swelling. CONCLUSIONS: Surgical decompression should be routinely performed when indicated before irreversible ischemic brain damage occurs.

Adolescent↗
PubMed2005

Surgical technique and results of endoscopic anterior spinal canal decompression.

OBJECT: Decompression of the spinal canal in the management of thoracolumbar trauma is controversial, but many authors have advocated decompression in patients with severe canal compromise and neurological deficits. Anterior decompression, corpectomy, and fusion have been shown to be more reliable for spinal canal reconstruction than posterior procedures; however, traditional anterior-access procedures, thoracotomy, and thoracoabdominal approaches are associated with significant complications. Endoscopy-guided spinal access avoids causing these morbidities, but it has not been shown to yield equivalent results in spinal canal clearance. This study was conducted to demonstrate the effectiveness of endoscopic spinal canal decompression and reconstruction quantitatively by using pre- and postoperative computerized tomography (CT) scanning. METHODS: Thirty patients with thoracolumbar canal compromise underwent endoscopic anterior spinal canal decompression, interbody reconstruction, and stabilization for fractures (27 cases), and tumor, infection, and severe degenerative disc disease (one case each). The mean follow-up period was 42 months (range 24 months-6 years). Neurological examinations, Frankel grades, radiological studies, and intraoperative findings were prospectively collected. Spinal canal clearance quantified on pre- and postoperative CT scans improved from 55 to 110%. A total of 25% of patients with complete paraplegia and 65% of those with incomplete neurological deficit improved neurologically. The complication rate was 16.7% and included one reintubation, two pleural effusions, one intercostal neuralgia, and one persistent lesion of the sympathetic chain. CONCLUSIONS: The authors describe the endoscopic technique of anterior spinal canal decompression in the thoracolumbar spine. The morbidities associated with an open procedure were avoided, and excellent spinal canal clearance was accomplished as was associated neurological improvement.

Adult↗
PubMed1999

Endoscopic orbital decompression with preservation of an inferomedial bony strut: minimization of postoperative diplopia.

With the increasing sophistication and safety of endoscopic orbital decompression, the technique is seen by many as an attractive and less morbid alternative to traditional open techniques. This rationale also makes the procedure more acceptable for individuals considering decompression for cosmetic reasons. As a result, complications such as postoperative diplopia assume greater significance. Preservation of an inferomedial bony strut has been postulated to reduce the incidence of postoperative diplopia in transconjunctival, but not endoscopic, orbital decompression for dysthyroid ophthalmopathy. We present a consecutive series of 11 subjects (21 eyes) who underwent transnasal endoscopic medial and inferior decompression of the orbits bilaterally. All patient charts were reviewed in a retrospective fashion and ophthalmologic, surgical, and cosmetic data were recorded, with callback of patients with incomplete data sets. All cases were performed under general anaesthesia. Preservation of the strut was possible in 15 of 21 eyes. Visual acuity was preserved or improved in all 21 eyes. Average ocular recession based on Hertel measurements was 3.6 mm and there were no surgical complications. New-onset or worsening diplopia was noted postoperatively in 2 of 11 subjects. However, in patients where both struts were preserved, there was zero incidence of postoperative diplopia (0/6). These results indicate that preservation of an inferomedial bony strut is not only technically feasible but also does not compromise the adequacy of decompression. The results also suggest that preservation of the inferomedial bony strut during endoscopic orbital decompression can reduce the incidence of postoperative diplopia.

Chi-Square Distribution↗
PubMed1990

Making core decompression work.

Meaningful assessment of a treatment modality for osteonecrosis (ON) must take into account a number of factors: (1) an accurate diagnosis, (2) consistent staging of the disease process, (3) understanding of the variability of the disease, (4) consistent application of the treatment modality (or the surgical technique), and (5) a clear understanding of the goal of the treatment used. This article reviews the important steps of a diagnostic algorithm that has been used to accurately diagnose and stage the disease process of ON. A consistent surgical technique with clearly defined goals is also outlined. The results of two clinical studies that were based on these diagnostic and therapeutic philosophies and that assess the role of core decompression in the treatment of ON are reviewed. The first study compared core decompression to conservative management in a prospective randomized study of 55 hips. Decompression provided more predictable pain relief and changed the indications for further surgical intervention more consistently than did conservative management. The second study represents a preliminary review of a ten-year study of the decompression procedure; it showed that core decompression was particularly useful in Stage I and Stage II ON. Roentgenographic stabilization was most predictable for Stage I hips. Core decompression can be a safe, effective, and predictable procedure in the treatment of Stage I and Stage II ON.

Adult↗
PubMed1995

Core decompression of the femoral head for avascular necrosis: indications and results.

OBJECTIVE: To evaluate the effectiveness and safety of core decompression in the treatment of avascular necrosis (AVN) of the femoral head. DESIGN: A case study. SETTING: The department of orthopedic surgery in a major university hospital. PATIENTS: All patients with AVN of the femoral head, stages I to IVA, were included regardless of the cause of the necrosis. Three hundred hips were available for analysis. The follow-up ranged from 2 to 12 years. INTERVENTION: Core decompression of the femoral head was performed with an 8-mm Michele trephine inserted from just below the greater trochanter into the centre of the necrotic lesion to within 5 mm of the articular surface. Two more trephine tracts were made with a 5-mm or 6-mm trephine. The normal portion of cancellous bone recovered from the intertrochanteric region was thinned with a rongeur and was placed loosely into the central decompression channel at the end of the procedure to serve as a graft. MAIN OUTCOME MEASURES: Anteroposterior and lateral radiographs, taken immediately before surgery and at the final follow-up, clinical hip evaluation according to the Harris scoring system, and the need for total hip replacement. RESULTS: One patient sustained a subcapital fracture 1 month after surgery due to a fall. There was one case of nonfatal pulmonary embolism, one case of pneumonia and one case of thrombophlebitis of the thigh. Forty-six percent of operatively managed hips showed no radiographic progression of disease compared with only 19% of nonoperatively managed hips. Thirty-five percent of the operatively managed hips required total hip replacement compared with 77% of nonoperatively managed hips. The results in hips with early (stages I and II) AVN were only slightly better than those of hips with advanced (stages III and IVA) disease. However, the results in hips with small areas of necrosis in both stages I and II were much better than those with larger lesions; only 7% of the former group required total hip replacement after decompression and cancellous bone grafting. CONCLUSIONS: Core decompression with cancellous bone grafting is a safe and effective procedure for the treatment of early AVN of the femoral head. Results with this form of treatment are considerably better than those obtained in patients treated nonoperatively. Decompression with or without bone grafting is the author's treatment of choice for patients with early AVN of the femoral head.

Bone Transplantation↗
PubMed1993

Decompression for degenerative spondylolisthesis and spinal stenosis at L4-5. The effects on facet joint morphology.

Anatomic variations exist in the facet joint orientation, shape, and size at L4-5. This morphology is further modified by degenerative changes in spinal stenosis and degenerative spondylolisthesis. This study explored the morphologic alteration of "pedicle-to-pedicle" decompression on the facet joints in normal patients, spinal stenosis patients, and degenerative spondylolisthesis patients. Using computerized digitization, computed tomographic scan images of the facet joint at L4-5 and the medial border of the pedicle at L5 were superimposed. The facet joint orientation, coronal dimension, percentage, and absolute reduction in coronal dimension after pedicle-to-pedicle decompression, and residual coronal dimension after decompression at L4-5 were measured for the three groups. There is a significantly reduced coronal dimension of the facet joint in degenerative spondylolisthesis patients compared with spinal stenosis and normal patients (P < 0.01). The average reduction of the facet joint coronal dimension is 34% (SD 30%) in degenerative spondylolisthesis, and 36% (SD 25%) in spinal stenosis. The smaller preoperative coronal dimension in degenerative spondylolisthesis leads to a significantly reduced residual coronal dimension in degenerative spondylolisthesis compared with normal patients (5.9 mm [SD 4.3 mm] vs. 9.3 mm [SD 3.5 mm]), respectively. Wide variations in facet joint reduction and residual facet joint coronal dimension exist. The significantly reduced coronal dimension after decompression in degenerative spondylolisthesis may be correlated to a trend to further anterior displacement if it is treated with decompression alone. Case-specific assessment of residual facet joint morphology after decompression in both spinal stenosis and degenerative spondylolisthesis patients should be integrated into decisions about fusion for stability at the L4-5 level.

Aged↗
PubMed1993

Foramen magnum decompression with removal of the outer layer of the dura as treatment for syringomyelia occurring with Chiari I malformation.

The surgical results of foramen magnum decompression in seven patients with syringomyelia associated with Chiari I malformations are reported. The patients were two men and five women, ranging in age from 23 to 54 years (mean, 30 yr). A bony foramen magnum decompression combined with the removal of the outer layer of the dura mater was performed in seven patients. In an average postoperative follow-up period of 2 years (range, 1-3 yr), neurological symptoms and signs improved in six of seven patients and were unchanged in one patient. Postoperative magnetic resonance imaging scans taken a few weeks after surgery showed a decrease in the size of the syrinx or a disappearance of the syrinx in five of seven patients; a few months were required for a similar reduction in the remaining two patients. In all seven patients, the decompression of the foramen magnum proved to be sufficient, as disclosed by postoperative magnetic resonance imaging. Foramen magnum decompression by our surgical technique is advantageous because all the procedures are extradural and there are, therefore, fewer postoperative complications than the foramen magnum decompression techniques previously reported. Foramen magnum decompression by the authors' surgical technique is effective as the initial surgical treatment for syringomyelia associated with Chiari I malformations.

Adult↗
PubMed1997

Long-term effects of core decompression by drilling. Demonstration of bone healing and vessel ingrowth in an animal study.

Avascular necrosis of the femoral head is associated with bone marrow hyperpression. Although core decompression by drilling is an accepted treatment regimen, until today no experimental results exist concerning the physiological effects of this procedure. Published clinical data are controversial. In an animal study marrow decompression was carried out by drilling of both hips in 18 healthy male sheep. In the right hip of each animal a resorbable stent was implanted in order to prolong the duration of core decompression. Over a time period of 24 weeks the effects were studied by measurement of the intraosseous pressure, by the plastination method and by morphological examination with light and electron microscopy. Bone drilling is a procedure of high short-time efficacy in decompressing the bone marrow. But decompression lasts only for a short time period. Three weeks postoperatively the drill channel is sealed by hematoma and fibrous tissue in both hips (with/without stent) and no significant decompressive effect is measured. Ingrowth of vessels along the drill channel is found in all hips after a time period of 3 weeks. These vessels originate from the periosteum as well as from the bone marrow and form temporary anastomoses between the periostal-diaphyseal-metaphyseal and the epiphyseal-physeal circulatory system. In conclusion, for the first time an anastomosis induced by drilling between both circulatory systems of bone is demonstrated and the importance of the periosteum is confirmed. The time of decreased core pressure induced by drilling is too short for substitution of a necrotic area and could be the explanation of the inferior clinical results of the procedure.

Animals↗
PubMed1981

Central venous bubbles and mixed venous nitrogen in goats following decompression.

Decompression of awake goats from saturation at 1, 2, and 3 ATA of air has been carried out using ultrasonic Doppler bubble detection, central venous blood inert gas measurement, and cardiac output measurement. The results of these experiments indicate that the decrease in nitrogen elimination rate as an apparent result of decompression cannot be due to excessive cardiac output or mass transport of a large amount of inert gas to the lungs as bubbles. Rather, the rapid drop in mixed venous nitrogen content is consistent with a generalized decrease in tissue-to-blood nitrogen elimination. This in turn appears to be due to a cardiovascular response to the decompression insult as was previously reported for dogs (D'Aoust et al., J. Appl. Physiol. 41: 348--355, 1976) at 1, 2, and 3 ATA; addition of ultrasonic Doppler monitoring and cardiac output in the present studies allowed measurement of the degree of latency in the appearance of bubbles at a central venous location. This time period includes that required for bubble formation, growth, and vascular transport of the bubbles to the Doppler detector. All results of these studies are consistent with the interpretation that due to a decompression insult, which probably includes bubble formation, some degree of hemostasis, and other hematologic sequelae, the transport of tissue inert gas to the capillary venous blood is retarded, thus providing the rapid apparent decrease in mixed venous blood inert gas content. These results demonstrate what is most likely a general response to a severe but not crucial decompression by the cardiovascular system.

Animals↗
PubMed1984

On the likelihood of decompression sickness.

The occurrence of decompression sickness in animals and humans is characterized by the extreme variability of individual response. Nevertheless, models and analyses of decompression results have generally used a critical value approach to separate safe and unsafe decompression procedures. Application of the principle of maximum likelihood provides a formal and consistent way to quantify decompression risk and to apply models to data on decompression outcome. By use of the maximum likelihood principle, a number of models were fit to data from dose-response and maximum pressure-reduction experiments with both rats and men. Several different formulations of two- and three-parameter models described the data well. In addition to summarizing data sets, the analyses provide a way to maximize the value of experimental observations, test theoretical predictions, estimate uncertainty in conclusions, and recommend safe practices.

Air↗