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PubMedDate not supplied

Dyspnea management in alpha-1 antitrypsin deficiency: effect of oxygen administration.

BACKGROUND: A deficiency of alpha-1 antitrypsin (AAT) can lead to pulmonary disease in middle-aged adults in whom dyspnea management can be a significant issue. OBJECTIVE: The research addressed whether short-term oxygen (O2) administration during activities might decrease dyspnea and improve exercise performance in nonhypoxemic patients with emphysema caused by a deficiency of alpha-1 antitrypsin. METHOD: This was a double-blind, randomized crossover study of 31 subjects with a deficiency of AAT (mean + SD, age = 47 +/- 7), moderate emphysema and a resting PaO2 > 70 mm Hg. Oxygen saturation (SpO2), 6-minute walk distance, and end of walk dyspnea were measured during three practice walks and during walks with nasal cannula administration of O2 (intervention) and compressed air (control). RESULTS: Repeated measures analysis of variance (ANOVA) showed significant differences across the walks for SpO (F= 18.9, p = 0.0001), 6-minute walk distance (F= 6.07, p = 0.004), and dyspnea (F= 4.44, p = 0.016). Using post hoc contrasts, SpO2 was the only variable that differed between 20, and compressed air (p < 0.0001). There was, however, an interaction effect of gender with O2 for dyspnea (F= 9.85, p = 0.004). Mean values showed that men did not benefit from O2 (p = 0.87). However, women experienced less dyspnea when receiving O2 as compared with compressed air (p = 0.0025), and although not statistically significant, the lower dyspnea with O2 corresponded with an increased walk distance of 79 feet. CONCLUSIONS: O2 administration may be useful for reducing dyspnea during exercise in selected populations.

Adult↗
PubMed2000

Does diving damage the brain? MR control study of divers' central nervous system.

PURPOSE: To evaluate the prevalence of cerebral white matter changes on MR imaging in healthy elderly compressed air divers with a long diving history in comparison with control subjects who have never dived. MATERIAL AND METHODS: The investigation employed 59 experienced elderly divers and 48 control subjects matched for age, body mass index, alcohol and smoking history. MR studies included a fluid attenuated inversion recovery sequence and T1- and T2-weighted pre- and postcontrast images in axial orientation of the whole brain to localize white matter changes. RESULTS: MR images did not show any morphologic abnormalities in the brains of divers. Both groups - divers and controls - did not differ significantly with respect to white matter changes of the brain. CONCLUSION: No increased prevalence of cerebral white matter changes in compressed air divers compared with a healthy worker sample of similar age were found. Thus, extensive compressed air diving may not necessarily be related to radiological changes on MR.

Adult↗
PubMed2005

Proinflammatory and anti-inflammatory cytokine balance in gasoline exhaust induced pulmonary injury in mice.

Proinflammatory and anti-inflammatory cytokine balance and associated changes in pulmonary bronchoalveolar lavage fluid (BALF) of unleaded gasoline exhaust (GE) exposed mice were investigated. Animals were exposed to GE (1 L/min of GE mixed with 14 L/min of compressed air) using a flow-past, nose-only, dynamic inhalation exposure chamber for different durations (7, 14, and 21 days). The particulate content of the GE was found to be 0.635, +/-0.10 mg PM/m3. Elevated levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were observed in BALF of GE-exposed mice, but interleukin 1beta(IL-1beta) and the anti-inflammatory cytokine interleukin-10 (IL-10) remained unaffected. GE induced higher activities of alkaline phosphatase (ALP), gamma-glutamyl transferase (gammaGT), and lactate dehydrogenase (LDH) in the BALF, indicating Type II alveolar epithelial cell injury, Clara-cell injury, and general toxicity, respectively. Total protein in the BALF increased after 14 and 21 days of exposure, indicating enhanced alveolar-capillary permeability. However, the difference in the mean was found statistically insignificant in comparison to the compressed air control. Total cell count in the BALF of GE-exposed mice ranged between 0.898 and 0.813x10(6) cells/ml, whereas the compressed air control showed 0.65x10(6) cells/mL. The histopathological changes in GE-exposed lung includes perivascular, and peribronchiolar cuffing of mononuclear cells, migration of polymorphonuclear cells in the alveolar septa, alveolar thickening, and mild alveolar edematous changes indicating inflammation. The shift in pro- and anti-inflammatory cytokine balance and elevation of the pulmonary marker enzymes indicate toxic insult of GE. This study will help in our understanding of the mechanism of pulmonary injury by GE in the light of cytokine profiles, pulmonary marker enzymes, and lung architecture.

Administration, Inhalation↗
PubMed1999

[Prospective lung function determination using an electronic miniature spirometer for detection of acute obstructive respiratory changes in diving students during occupational diving training].

BACKGROUND: Changes in lung function have been shown in experienced divers. The purpose of this study was to measure the pulmonary function of diving trainees who were not exposed to a hyperbaric environment before. METHODS: We measured the lung function in a sample of fifteen randomized selected young healthy non-smoking diving trainees parallel to fourteen open water dives. Five subjects used common compressed air diving apparatuses (breathing gas: 21% O2/78% N2) and ten subjects used closed circuit diving apparatuses (breathing gas compositions depended to the diving depths; 24 m: 60% O2/40% N2, 42 m: 40% O2/60% N2, 54 m: 32.5% O2/67.5% N2). The values (FVC, FEV1, PEF, MEF 25, MEF 50, MEF 75) were obtained by an electronic miniature-spirometer directly before descent, upon surfacing, and after one hour and four hours. RESULTS: The lung function values of the subjects who used compressed air showed no relevant impairment of lung function after the diving exposures. Significant (p < 0.05) post dive lung function reductions (FVC, FEV1, PEF, MEF 25, MEF 50, MEF 75), were evident in subjects using closed circuit diving apparatuses, after deep dives and shallow water dives. CONCLUSIONS: The decreased lung function of the used diving apparatuses. The impaired lung functions in subjects using closed circuit diving apparatuses may be induced by a subclinical lung edema generated by pressure differences between breathing gas and thorax tissues as well as the influences of soda-lime dust. Compared to compressed air diving the significantly increased oxygen partial pressures (p < 0.001) in closed circuit diving apparatuses may be an additional reason for the reversible airway obstructions.

Adult↗
PubMed2003

Effectiveness of duct cleaning methods on newly installed duct surfaces.

Two kinds of air duct cleaning methods, mechanical brushing with different brushes and compressed air cleaning, were compared in the laboratory and in newly built buildings. The ducts were contaminated either with test dust or with dust originated from a construction site. The amount of dust on the duct surface was measured with the vacuum test method and estimated visually before and after the cleaning. In addition, the cleaning times of the different techniques were compared and the amount of residual oil in the ducts was measured in the laboratory test. The brushing methods were more efficient in metal ducts, and compressed air cleaning was more efficient in plastic ducts. After the duct cleaning the mean amount of residual dust on the surface of the ducts was <or=0.1 g/m2 in the laboratory test with ducts contaminated at construction site and <or=0.3 g/m2 after cleaning in the field. The decrease in the dust deposits on the surface ranged from 86 to 99% and from 75 to 94% in the ducts cleaned in the laboratory or in the building site, respectively. The oil residues and the dust stuck onto the oil were difficult to scrape off and remove, and none of the cleaning methods were capable of cleaning the oily duct surfaces efficiently enough. Thus new installations should consist only of oil-free ducts.

Air Pollution, Indoor↗
PubMed1989

The effect of oxygen on respiration and sleep in patients with congestive heart failure.

STUDY OBJECTIVE: To determine the effect of supplemental oxygen on Cheyne-Stokes respiration, nocturnal oxygen saturation (SaO2), and sleep in male patients with severe, stable congestive heart failure. DESIGN: Randomized, single-blind, placebo-controlled crossover study. SETTING: Patients referred from outpatient cardiology clinics of two teaching hospitals. PATIENTS: Sequential sample of nine outpatients with severe, stable congestive heart failure. INTERVENTIONS: For each patient, sleep studies (after an adaptation night) from two consecutive randomized nights were compared; one study was done while the patient breathed compressed air and the other while the patient breathed oxygen (O2). Compressed air and oxygen were both administered through nasal cannulae at 2 to 3 L/min. MEASUREMENTS AND MAIN RESULTS: Cheyne-Stokes respiration, defined as periodic breathing with apnea or hypopnea, was found in all patients. Low-flow oxygen significantly reduced the duration of Cheyne-Stokes respiration (50.7% +/- 12.0% to 24.2% +/- 5.4% total sleep time), mainly during stage 1 NREM (non-rapid eye movement) sleep (21.3% +/- 7.1% to 6.7% +/- 2.3% total sleep time) with no significant change during stage 2 sleep, slow-wave sleep, or REM (rapid eye movement) sleep. Although patients had normal SaO2 (96.0% +/- 1.7%) while awake, severe sleep hypoxemia was common; breathing oxygen reduced the amount of time that SaO2 was less than 90% from 22.3% +/- 8.0% to 2.41% +/- 1.93% of total sleep time. Sleep, disrupted to a variable extent in all patients, improved with oxygen therapy: There was an increase in total sleep time from 275.3 min +/- 36.6 to 324.6 min +/- 23.3; a reduction in the proportion of stage 1 sleep (27.6% +/- 5.8% total sleep time to 15.2% +/- 2.6% total sleep time); and a reduction in the number of arousals (30.4/h +/- 8.0 to 13.8/h +/- 1.9). The apnea-hypopnea index was reduced from 30.0 +/- 4.7 to 18.9 +/- 2.4 with oxygen breathing. CONCLUSION: In severe, stable congestive heart failure, nocturnal oxygen therapy reduces Cheyne-Stokes respiration, corrects hypoxemia, and consolidates sleep by reducing arousals caused by the hyperpneic phase of Cheyne-Stokes respiration. Correction of nocturnal hypoxemia and sleep disruption may improve the clinical status of these patients.

Adult↗
PubMed1994

Basic nebulizer function.

The main function of a jet nebulizer is to aerosolize the contained liquid. The primary generation point is the orifice where the compressed air expands and increases in velocity. At this point the expanding air induces an underpressure and liquid is sucked up to the air orifice where it meets the rapidly expanding air. Droplets from the liquid surface are carried away with the airstream towards the baffle system. After cut-off by impaction on the baffle surface, secondary generation occurs on the baffle as droplets are produced due to high air velocity. Several different designs of nebulizer are available. The differences cause variation in the output characteristics; for example, in the liquid output and droplet size distribution. There is also disparity between individual nebulizers of the same brand. This is due to manufacturing errors. Repeated use of a single nebulizer over time causes ageing. This, in turn, causes the critical points of droplet generation to change. The most significant changes are the small increases in the diameter of the air orifice. This may be due to mechanical wear from the compressed air source or to extensive cleaning procedures. The effect of the increasing diameter, as seen by the user, is decreased driving pressure at a constant rate of air flow. There is also an effect on the output characteristic of the nebulizer. With decreasing driving pressure the air velocity decreases. This in turn, increases the droplet size generated at the air orifice.(ABSTRACT TRUNCATED AT 250 WORDS)

Equipment Design↗
PubMed1980

Lightweight remotely actuated switching valve for rebreathing exercise studies.

A new type of switching valve used in rebreathing studies for estimating cardiac output is described. This valve employs a unique deformable elastic element, actuated by low-pressure compressed air, to effect switching. The capability for remote operation (via a compressed air line) and the light weight of the valve (110 g) make the valve especially well suited to exercise stress testing studies. Two valves of this type have been satisfactorily used in graded exercise stress tests in a clinical setting for over 2 yr.

Carbon Dioxide↗
PubMed1993

Salmeterol provides prolonged protection against exercise-induced bronchoconstriction in a majority of subjects with mild, stable asthma.

In patients with asthma, exercise-induced symptoms are well recognized and frequently limiting. Currently available beta 2-receptor agonists have a short duration of action and breakthrough symptoms may occur. We studied the efficacy of the recently developed long acting inhaled beta 2-agonist salmeterol with respect to protection against exercise-induced bronchoconstriction. Twelve patients with mild to moderate, stable asthma were recruited (age range 21-33 years). They each underwent treadmill exercise tests, with target heart rate of approximately 90% of predicted maximum, 1, 6 and 12 h after a single dose of salmeterol 50 micrograms, salbutamol 200 micrograms and placebo. Patients breathed through a two-way valve, inspiring dry air from a compressed air cylinder via a Douglas bag to maintain constant humidity. The primary efficacy variable analysed was the maximum percentage fall in FEV1 and FVC from pre-exercise readings within the first 30 min post-exercise. At 1 h post-dose there was significant protection in terms of fall in mean +/- SEM FEV1 in response to exercise challenge after either salmeterol (0.83 +/- 6.2%) or salbutamol (3.8 +/- 5.5%) as compared with placebo (27.1 +/- 7.3%). At 6 h post-dose, fall in FEV1 on salmeterol was 11.3 +/- 3.8% as compared with salbutamol, 28.0 +/- 5.7% and placebo, 32.0 +/- 7.0%. At 12 h post-dosing there was still significant protection in terms of fall in FEV1 in the salmeterol treated group, 12.8 +/- 4.9%, as compared with salbutamol, 28.7 +/- 4.9% and placebo, 25.4 +/- 7.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1983

Critical review of international standards for respiratory protective equipment - I. Respiratory protective equipment for particulate-laden atmospheres.

The standards for respiratory protective equipment (R.P.E.) from eleven countries and standards organizations were grouped according to type as particulate removing, gas and vapor removing, airline (fresh air hose and compressed air types), and self-contained breathing apparatus (open circuit and closed circuit). Each group of standards was further divided into specification and performance requirements. This paper is one in a series of three that highlights and critically reviews international respirator standards; it deals specifically with R.P.E. for protection against particulate-laden atmospheres. Great Britain, Australia, European Committee for Standardization (CEN), France, South Africa, Italy, Spain, New Zealand, Scandinavia, Japan, and Germany have standards for R.P.E. against particulate-laden atmospheres. Tabular summaries and accompanying discussion of national requirements are presented in the following categories: solid and liquid aerosol removal efficiency, clogging, and rough usage. Large differences and some notable omissions exist among standards. For example, the protection capacity of the filter can be tested by using solid particulate or liquid challenge aerosols. The majority of the countries evaluate protection capacity using solid particulate aerosols, while the remainder use both solid and liquid or liquid aerosols only. Other differences in filter testing deal with the composition of the test aerosol and the characteristic of the filter measured. The initial penetration or the penetration of the filter as it is being loaded over a specified period of time can be measured. In the latter case penetration is averaged over the test period and the degree of protection is assessed only for that overall time period; information is not provided concerning the protection afforded by the filter in the earlier stages of use.

Aerosols↗
PubMed1983

Surface treatment studies aimed at streamlining fissure sealant application.

Three laboratory studies were carried out with the aim of improving or streamlining enamel surface treatment procedures in fissure sealing. In Study 1, the effect of reducing acid etch time from 60 s to 10 s was assessed by SEM and tensile bond strength measurements. Reduction in etch time produced a finer etch pattern, gave a reduced but still high, bond-strength, albeit with slightly poorer long-term adhesion. Study 2 showed that a conventional acid etch treatment could completely remove acquired pellicle, without prior prophylaxis. SEM studies and bond-strength measurements corroborated this view. In Study 3, compressed air and chemical drying agents were compared for drying speed and efficiency. Compressed air gave more rapid, thorough drying, and greater resultant bond strengths.

Acid Etching, Dental↗
PubMed2005

Hydrostatic pressure/perfusion culture system designed and validated for engineering tissue.

Tissue engineering to replace or repair damaged tissues using three-dimensional cell constructs is a promising approach to promote tissue regeneration de novo. The production of cell constructs is a critical process for maintaining cell viability and phenotypes in vitro prior to surgical treatment. We have developed a novel hydrostatic pressure (HP)/perfusion culture system for three-dimensional cell constructs with application of mechanical stimuli with HP and continuous medium changes. In this study, we tested and validated the performance of this culture system. This systems' performance was stable at a constant HP up to 5 MPa and at a cyclic HP up to 0-5 MPa at 0.5-0.03 Hz. The performance of medium perfusion in the culture chamber showed laminar flow from an inlet into the chamber parallel to the inner walls. Air bubbles on all inner surfaces of the culture chamber caused unstable HP application because air can be compressed with greater ease than water, consequently impacting fluid compression. Air bubbles in a 3D agarose gel model disappeared due to HP over time and the spaces vacated by the air bubbles were replaced with water. Our validated HP/perfusion culture system allows for a well-regulated constant or cyclic HP application in culture medium and can be applied to other 3D tissue culture for engineering tissue.

Bioreactors↗
PubMed1995

Treadmill chamber for studies of respiratory gas exchange in the rat during exercise.

A treadmill for studying gas exchange in small mammals during exercise is presented. The system consists of a motor-driven running mat enclosed in a gastight chamber that receives a measured flow of air from a compressed air cylinder. The gas flow and temperature, pressure and instantaneous gas composition of the chamber (oxygen, carbon dioxide and water) are measured continuously and the data are computed to include the effects on chamber atmosphere of the rat activity, either running or at rest. The system is completed with a shock delivery grid that stimulates the rat to run. The calculations are based on the changes in the composition of the gas in the chamber (constantly stirred by a small electric fan) induced by the rat instead of relying on the alterations induced in the outflowing gas. The consumption of oxygen, and production of carbon dioxide and water by the rat are computed in real time, giving a very fast response to physiological change induced by exercise. The chamber is custom-made from an aluminium block and a plexiglass lid; all other components are available commercially. The system, as described, allows for a detailed analysis of respiratory gas (and water) exchange by rats under varying exercise conditions, there is practically no time lag between changes in respiratory gases and the detection of these changes, and the buffering effect of the chamber size is practically eliminated because of the calculation approach used.

Animals↗
PubMed1990

SEM evaluation of surface cracking in glass-ionomer cement.

In an effort to assess the influence of acid etching and air drying on the production of cracks in the surface of glass-ionomer cement, the two procedures were employed over progressively increased durations, and any resulting surface cracks in the cement, were examined by replica techniques under an SEM (Scanning Electron Microscope). The results showed that acid etching alone did not produce cracks, but air-drying by compressed air produced cracks at durations between 5 and 30 sec.

Acid Etching, Dental↗
PubMed1987

Continuous passive motion device for hand rehabilitation.

Prototypes have been designed and manufactured for a lightweight portable device which continually moves all the joints of the hand passively through a range of motion. Inflatable bag modules in the palm of the hand are ganged together to create the required range of motion. A battery-operated air pump cycles compressed air to the modules. Initial clinical experience with patients who have flexion contractures caused by burns, trauma, and Dupuytren's contractures has shown the device to be well tolerated and effective.

Burns↗
PubMed1983

Use of a fractional factorial design to evaluate granulations prepared in a fluidized bed.

Sulfadiazine granules were prepared in a fluidized bed granulator. The granulation conditions such as binder concentration, velocity and temperature of fluidizing air, pressure of compressed air and binder solution flow rate were studied at two levels, low and high. By applying fractional factorial design the effect of these granulation conditions as well as the interaction among them, on the granules physical characters were assessed.

Chemistry, Pharmaceutical↗
PubMed1974

Bone and joint lesions in decompression sickness.

1 Of 450 divers, 268 (59.5%) has aseptic necrosis of bone; 81 had articular lesions. 2 In proportion to duration of diving experience and maximum depth of diving, incidence of bone necrosis increases. 3 The radiological lesions have been classified by modified Ohta-Matsunaga criteria. 4 Yearly progress of bone changes were mentioned. 5 Pathological appearances of aseptic necrosis of bone in divers are compared with different types of bone necrosis. 6 Experimental studies for aseptic necrosis were mentioned. 7 Etiology of bone necrosis is not yet clear, but some etiological factors were discussed. It was suggested that fat embolism was an important factor, because fat embolisms were seen in our pathological findings of the divers and compressed-air workers. 8 Periodic radiological examination of the bones of divers and compressed-air workers should be carried out. It is important to research the new modified decompression table to prevent bone necrosis. 9 Surgical treatment of bone necrosis was mentioned.

Adolescent↗