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PubMedDate not supplied

[Changes in human evoked potentials during altitude decompression].

In order to evaluate the functional state of the optic analyzer during altitude decompression, the method of recording evoked potential to the light stimulus was used. Changes in the latent periods and energies of evoked potential waves were noted during different decompression regimes. It has been, therefore, concluded that the functional state of the optic analyzer alter before bends; during bends it changes more significantly; the response to a short-term effect of painless decompression and to painful symptoms of the disease is different.

Adult↗

PubMed2001

The U.S. Navy decompression computer.

The U.S. Navy has recently approved the Cochran NAVY decompression computer (DC) for use in Naval Special Warfare diving. This action represents the first approval of a diver-worn DC for use in the U.S. Navy. This paper reviews the development and testing of both the decompression algorithm and the hardware chosen for the Navy's DC. The decompression software in the Cochran NAVY is the VVAL 18 algorithm developed at the Navy Experimental Diving Unit (NEDU) by Captain Ed Thalmann. A discussion of the relative conservatism of the VVAL18 algorithm in comparison to the U.S. Navy Standard Air Tables and the basis for the differences between the two is provided. The initial guidelines establishing DC diving practice for the Navy SEAL community are outlined as are plans for future research efforts in U.S. Navy DC diving.

Algorithms↗

PubMedDate not supplied

[Revascularization decompression of the optic nerve: a new surgery of the optic nerve in progressive glaucomatous optic neuropathy].

A new operation on the optic nerve scleral canal, revascularization compression of the optic nerve, was carried out in 21 patients (21 eyes) in order to improve the visual functions and stabilize the glaucomatous process. The operation combines the advantages of decompression of the optic nerve by dissection of the posterior scleral ring with creation of an additional source of blood supply to the optic nerve from the myovascular bundle of the internal rectal muscle. Good functional effect and notable improvement of hemoperfusion of the optic nerve and retina were attained (period of observation up to 2 years). The degree of visual field extension correlated with the degree of increase in hemoperfusion values. Comparative analysis showed a higher functional efficiency of revascularization decompression of the optic nerve in comparison with optic nerve decompression, which is due to a more essential improvement of ocular hemoperfusion.

Aged↗

PubMed1975

Nitrogen elimination in man during decompression.

The effect of ambient pressure on inert gas elimination during decompression was investigated using human subjects breathing air in a dry hyperbaric chamber. This was done by measuring nitrogen recovery during three different decompression schedules following identical simulated dives. Five subjects were used, each with normal pulmonary function. In each case the simulated dives consisted of exposure for 40 min to air at 4 ATA corresponding to a depth of about 100 fsw and 28 degrees C. Following these exposures each subject was decompressed in different experiments to 50 fsw (2.515 ATA) and to 10 fsw (1.303 ATA) while breathing a mixture of 80:20 helium-oxygen. In addition, two of these subjects were denitrogenated isobarically, at 100 fsw, breathing 80:20 helium-oxygen. Significant differences in nitrogen-elimination rate were observed, with nitrogen removed most effectively at 50 fsw and least at 100 fsw. To explained these unexpected results it is tentatively suggested asymptomatic bubble formation occurred at both 10 and 50 fsw.

Decompression↗

PubMed2002

[Decompression and internal fixation in the treatment of thoracolumbar spine and spinal cord injury: report of 166 cases].

OBJECTIVE: To evaluate the therapeutic effect of several internal fixation methods in the surgical treatment of thoracolumbar spine and spinal cord injury (SSI-TL). METHODS: In the 166 SSI-TL cases included in this retrospective analysis, 37 had vertebral body burst fracture, 109 had vertebral body compression fracture (with compression to a degree over 50%),14 had vertebral body fracture and dislocation and 6 had multilevel vertebral fractures or jumping fracture. In view of the spinal cord injury 59 belonged to Frankel grade A, 46 grade B, 42 grade C and 19 grade D. Posterior decompression, reduction and internal fixation were performed in 122 patients and the other 44 underwent anterior decompression, reduction and ilium bone grafting. RESULTS: Follow-up study for 3 to 18 month was conducted in 123 cases, in which RF screws cracking occurred in 4 cases, Harrington upper hook dislocation in 5 cases and Harrington rod cracking in 6, while the rest cases were free of theses incidents. In terms of the function recovery of the spinal cord, 88 cases showed improvement of the spinal cord and cauda equina of 1 to 3 Frankel grades, leaving only 35 lingering in grade A. CONCLUSION: Decompression should be performed at early stages of SSI-TL, and employment of various internal fixation instrument helps maintain and enhance spinal stability, preventing secondary lesion of the spinal cord and promoting the function recovery of the injured spinal cord.

Adolescent↗

PubMed2002

The outcome of orbital decompression for thyroid associated ophthalmopathy.

OBJECTIVE: To evaluate the therapeutic results of orbital decompression for severe thyroid orbitopathy. METHODS: The records of 27 patients (30 eyes) having undergone orbital decompression of one wall, two walls and three walls for severe thyroid orbitopathy were analyzed for changes in visual acuity, visual field or pattern visual evoked potential, movement and reduction in proptosis. The indications were corneal exposure, severe proptosis and optic neuropathy. RESULTS: After surgery, the patients were followed up for a mean of 13.7 months. The visual acuity improved obviously in 19 eyes (63.3%), visual acuity was improved slightly in 4 eyes (13.3%), visual acuity kept in 0.2 - 0.8 (no change) in 4 cases (13.3%), visual acuity deteriorated obviously and not recovered in 3 eyes (10.0%). Proptosis was decreased by a mean of 3.6 mm (range 1 - 7 mm), the decrease >/= 2.0 mm being in 93.3% eyes. CONCLUSION: Orbital decompression is effective in improving vision in most patients with severe thyroid associated ophthalmopathy, and the proptosis can be effectively improved.

Decompression, Surgical↗

PubMed2002

Slow decompression of the bladder using an intravenous giving set.

Rapid decompression of the bladder has been associated with complications such as diuresis, hyperkalaemia, haematuria and hypotension. Although these complications are easily managed and rarely clinically significant, clinicians still practise slow decompression using a 'clamping' technique. Slow decompression using a giving set provides a more convenient and less time-consuming way of achieving this goal.

Acute Disease↗

PubMed2002

Diving methods and decompression sickness incidence of Miskito Indian underwater harvesters.

Diving conditions, dive profiles, and symptoms of decompression sickness (DCS) in a group of Miskito Indian underwater seafood harvesters are described. Dive profiles for 5 divers were recorded with dive computers, and DCS symptoms were assessed by neurological examination and interview. Divers averaged 10 dives a day over a 7-day period with a mean depth of 67 +/- 7 FSW (306 +/- 123 kPa) and average in-water time of 20.6 +/- 6.3 minutes. Limb pain was reported on 10 occasions during 35 man-days of diving. Symptoms were typically managed with analgesic medication rather than recompression. Indices of the decompression stress were estimated from the recorded profiles using a probabilistic model. We conclude that the dives were outside the limits of standard air decompression tables and that DCS symptoms were common. The high frequency of limb pain suggests the potential for dysbaric bone necrosis for these divers.

Adult↗

PubMed1976

Effect of physical activity of airline flight attendants on their time of useful consciousness in a rapid decompression.

To determine the effect of physical activity on the "time of useful consciousness" (TUC) of airline flight attendants in a rapid, severe decompression, 10 male and 10 female subjects were exposed to a decompression profile while at rest and performing light-to-moderate work. Decompression from 6,500 to 34,000 ft (2,000 to 10,400 m) was followed by descent at 5,000 ft/min (1,500 m/min). The average TUC for the males decreased from 54 s (omega 7.1) at rest to 34 s (omega 4.4) while performing work. The average TUC for the females decreased from 54 s (omega 8.1) at rest to 32 s (omega 4.0) while performing work. Supplemental oxygen had a marked paradoxical effect when the subjects were performing work.

Aerospace Medicine↗

PubMed1999

[Transantral orbit decompression to malignant ophthalmopathy].

OBJECTIVE: To recognize the indication and the value of transantral orbit decompression to malignant ophthalmopathy. METHOD: 9 eyes of 5 cases undergone transantral orbital decompression from November 1986 to October 1998 were reviewed. RESULT: After 3 months-2 years of follow-up. We found this approach successfully improved visual function of all 5 cases. Average proptosis reduction was 5 mm. The eye lids could be closed in 4 of the 5 cases and the palpebral fissures was decreased 1-2 mm in 1 of the 5 cases. Preoperative exposure keratitis resolved in both of the 2 cases. Diplopia was cured in both of the 2 cases. Secondary glucorna also recovered in both the 2 cases. Disturbance of ocular motility in both of the 2 cases improved postoperatively and preoperative visual acurity worsen also improved in both of the 2 cases. CONCLUSION: It has been suggested that the transantral decompression of the orbit provided a safe, effective therapeutic modality for patients with vision-threatening or major cosmetic problem.

Adult↗

PubMed2003

Prophylactic high dose methylprednisolone fails to treat severe decompression sickness in swine.

INTRODUCTION: Controlled decompression from saturation conditions is not always an option, particularly in a disabled submarine scenario. Hypothesis Prophylactic high dose methylprednisolone (MP) would improve outcome in severe cases of decompression sickness (DCS). METHODS: Littermate pairs of male Yorkshire swine (n = 86, mean weight +/- SE = 19.3 +/- 0.2 kg) were randomized to one of three groups, then compressed on air to 4.3 ATA (33 msw) for 22 h and brought directly to surface pressure (1 ATA) at 0.9 ATA x min(-1). The MP-50 group received i.v. infusion of 50 mg x kg(-1) of MP dissolved in 60 cc normal saline (NS) immediately prior to the hyperbaric exposure. The NS group received 60 cc NS i.v. immediately prior to the hyperbaric exposure. The MP-10 group received i.v. infusion of 10 mg x kg(-1) MP dissolved in 60 cc NS during the hyperbaric exposure, 7 h before the decompression. RESULTS: Outcomes of severe DCS and death were recorded. NS group: 14 DCS, 4 died; MP-50 group: 19 DCS, 12 died; MP-10 group: 19 DCS, 10 died. Compared with the NS group, logistic regression analysis suggested that animals in the MP-10 group were more likely to get severe DCS and to die (p < 0.01) and animals in the MP-50 group were more likely to die from their disease (p < 0.01). DISCUSSION: Prophylactic high dose MP exerts no protective effect against severe DCS and actually worsens mortality in this model. An earlier group of untreated controls (UC, n = 44, 30 DCS, 11 died, mean weight +/- SE = 19.9 +/- 0.3 kg) exposed to the same profile was also available for analysis. Comparison of the UC and NS animals suggested that pre-dive NS treatment may protect against severe DCS.

Analysis of Variance↗

PubMed2003

Field trials of no-decompression stop limits for diving at 3500 m.

INTRODUCTION: In 1990, Boğaziçi University (Istanbul, Turkey) launched an altitude diving program to develop techniques and safe decompression profiles for diving at high terrestrial altitudes. Following pioneering diving expeditions to lakes at high elevations in 1990-1992, it was deemed necessary to calculate new tables. METHODS: Bottom time limits for dives requiring no decompression stops (no-d) were calculated for 3500 m using linear extrapolation of U.S. Navy M-values decreased by 4 ft of sea water (M4 limits). These limits were tested for 15, 18, 21, 24, 27, and 30 m of depth by diving in the Great Sea Lake at Mt Kaçkar (3412 m) with 10 dives per profile. RESULTS: The mean decompression sickness (DCS) risk estimated from precordial bubble scores (Spencer Scale) ranged from 0.3% to 2.8% per profile. After three expeditions, 165 dives had been achieved with a cumulative bottom time of 3199 min. No DCS occurred in dives that adhered to the M4 no-d limits. However, two cases of Type I and one case of Type II DCS were encountered where the divers accidentally exceeded those limits. DISCUSSION: Considering the estimated risk of DCS and the relatively small number of trials, a more conservative approach was used to develop a final set of high altitude dive tables. This conclusive approach used continuous compartment half-lives. It is based on fitting a surface of allowable supersaturation limits using the empirical M-values from existing tables as well as our altitude diving data, together with an added constraint that forces calculated M-values to stay below the available M-value data.

Adult↗

PubMed2003

Anterior decompression and instrumentation with cervical butterfly-like locking plate system for herniated cervical intervertebral discs.

OBJECTIVE: To evaluate the clinical efficacy of anterior decompression and internal fixation with cervical butterfly-like locking plate system (CBLP, made in China) in the treatment of cervical intervertebral disc herniation. METHODS: This study included 16 patients with cervical intervertebral disc herniation, aged from 26 to 46 years (36.2 years on average), with the disc hernia occurring in single segment in 12 and 2 segments in 4 cases. The patients received anterior decompression, autogenous iliac bone grafting and internal fixation with CBLP, and follow-up studies lasting for 12 to 24 months (mean 18 months) were conducted in all the cases. RESULTS: All the patients had significant improvements in terms of symptom alleviation without any complications during the follow-up period. Solid bone fusion was achieved within an average period of 3 months, and no screw loosening or plate failure occurred. CONCLUSION: Anterior decompression and internal fixation with CBLP proves to be effective for managing cervical intervertebral disc herniation.

Adult↗

PubMed2002

[Anterior decompression and reconstruction in the treatment of thoraco-lumbar burst fractures].

OBJECTIVE: To describe the clinic results and advantages of anterior decompression and reconstruction in the treatment of thoraco-lumbar burst fractures. METHODS: Sixty-seven cases with the thoraco-lumbar fractures accompanied with the compression of the spinal cord were treated by anterior decompression and internal fixation. The Frankel impair scale of preoperation and postoperation was observed. RESULTS: The follow-up was 30.1 month in average. All postoperation spinal alignments were good. No secondary kyphnosis occurred; in 95.4% of the patients, the Frankel score rose more than one degree. CONCLUSION: Anterior decompression is complete and anterior reconstruction is strong, and both are fit to spinal biomechanical characteristics.

Adolescent↗

PubMed1976

The theory of high-altitide corrections to the U.S. Navy standard decompression tables. The cross corrections.

The theoretical basis for the Cross high-altitude corrections to the USN Standard Decompression Tables is derived. Providing corrections are made for depth and ascent rate and if no decompression stops are made, a dive at altitude can be transformed to a dive at sea level for which the theoretical tissue responses are mathematically similar to the altitude dive. The transformation fails if decompression stops are required due to the fact that the stop criteria used in the USN Tables do not obey the same rule of transformation. It is shown that the failure of the high-altitude correction is expected to be conservative.

Air↗

PubMed2003

[Causes of ineffectiveness of microvascular decompression for hemifacial spasm].

OBJECTIVE: To study causes of ineffectiveness of microvascular decompression (MVD) in treatment of hemifacial spasm (HFS). METHODS: Reoperative MVD was performed in 23 HFS patients with previous ineffective MVD. In the patients, the main causes of ineffectiveness included misjudgment of compressing vessels (7 patients), improper insertion of decompressing grafts (9), improper selection of grafts (5) and small grafts (2). RESULTS: Symptoms of HFS disappeared immediately after the second MVD in 21 patients and delayed in 2 patients (after 2 weeks, 6 weeks). No recurrence of HFS was noted during the follow-up period of 1.0 - 6.0 years (mean 3.4 years). CONCLUSIONS: MVD is an effective microsurgical method for treating HFS. Accurate judgement of compressing vessels and proper decompression are the key to surgical effectiveness.

Adult↗

PubMed2002

[Endoscopic transnasal orbital decompression for dysthyroid orbitopathy].

OBJECTIVE: To evaluate the effect of endoscopic transnasal orbital decompression for patients with dysthyroid orbitopathy. METHODS: Nine cases (15 eyes) of dysthyroid orbitopathy were included in this study. All patients were treated by transnasal endoscopic orbital decompression. RESULTS: The follow-up ranged from 6 months to 2 years. Proptosis measured' by exophthalmoter reduced from (21.93 +/- 1.49) mm to (16.87 +/- 1.25) mm after operation. The visual acuity improved from 0.57 +/- 0.12 to 0.69 +/- 0.12, the palperbral fissures reduced from (11.07 +/- 1.44) mm to (8.20 +/- 1.15) mm. Postoperatively, the orbital pressure was significantly decreased as compared with the preoperative result (P < 0.001). Diplopia was cured in 3 of 7 cases. CONCLUSION: Endoscopic transnasal orbital decompression is an effective method for the treatment of dysthyroid orbitopathy.

Adult↗

PubMed1992

The influence of prior exercise at anaerobic threshold on decompression sickness.

This study was conducted to examine the effects of exercise prior to decompression on the incidence of altitude decompression sickness (DCS). In a balanced, two-period, crossover trial, 39 healthy individuals (29 males, 10 females) of mean (S.D.) age 32.5 (7.7) years and body mass index 23.7 (3.4) were each exposed twice, without denitrogenation, to an altitude of 6,400 m (21,000 ft) in a hypobaric chamber. Under the experimental condition, subjects exercised at their predetermined anaerobic threshold levels for 30 min each day for 3 d prior to altitude exposure; the other condition was a non-exercise control. Under both conditions, subjects performed exercise simulating space extravehicular activities at altitude for a period of 3 h, while breathing 100% oxygen. There were nine preferences (untied responses) for DCS, four under control and five under experimental conditions; all were Type I, pain-only bends. No carryover effect between exposures was detected, and the test for treatment differences showed p = 0.56 (95% confidence interval = 0.34-0.58) for symptoms. No significant difference in DCS preferences was found after subjects exercised up to their anaerobic threshold levels during the days prior to decompression.

Adult↗