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At least 19 recordsLinked to original sources
PubMed1992

[Comparison of lung function parameters in healthy non-smokers following exertion in urban environmental air and in air-conditioned inside air].

This study examines the question whether young healthy nonsmokers show differences in parameters of lung function after having been exposed to exercise in city air and to the same exercise in air-conditioned room air. For this purpose 16 young nonsmokers of age 20-39 years (10 men: 26.6 +/- 5.2, 6 women: 22.2 +/- 1.4) exercised maximally once on a bicycle ergometer in city air for 8 minutes and 48 hours later in air-conditioned room air on the same ergometer also for 8 minutes. The forced vital capacity, the forced expiratory volume in 1 second (FEV1) and peak expiratory flow rates were determined before exercise, immediately after, and after the rest of 10, 30, 60, and 120 minutes. The following results were obtained: 1. In city air the continuously recorded concentrations of NO2 showed a mean value (+/- 1 SD) of 71.6 micrograms/m3 (+/- 23.2) and thus about 10 times higher than in air-conditioned room air, where the mean value of NO2 was 7.5 micrograms/m3 (+/- 3.5). 2. 10, 30, 60, and 120 minutes after exercise in city air the mean FEV1 values were about 2.5-3% lower than in room air. Even though these differences were small, they were significant (10 minutes after exercise p = 0.006, 30 minutes p = 0.011, 60 minutes p = 0.025, and 120 minutes p = 0.016). 3. The FEV1 differences were more pronounced in males. The males were, due to conditions beyond our control, exposed to higher NO2 and NO concentrations in city air than females.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1979

[Studies on the performance of the dental air turbine handpieces. (Part 1). Air pressure and bur length to be influenced over the rotational performance of the air bearing type handpieces (author's transl)].

Air turbine handpieces are used as the dental cutting instruments for the clinical use and many appliances. But, there are no studies on the performance of air turbine handpieces. So, this paper shows the rotational performance of air turbine handpieces which are influenced over the supplying air pressure and cutting bur length. Experimentally used air turbine handpieces is air bearing type and it's set up air pressure to be supplied is 3.5 kg/cm2. So, in this experiments, the range of air pressure is 1.8 approximately 3.5 kg/cm2, which is established five stages. And the bur length of the rotational parts is 5 approximately 9 mm with five steps. As the results, the rotational performance of air handpieces are influenced over these factors of the air pressure and the bur length. And air pressure to be supplied are influenced to be not only over the rotational speed but the load for the putting a stop to the revolutions.

Air Pressure↗
PubMed1992

Modification of a new catheter for air retrieval and resuscitation from lethal venous air embolism: effect of nitrous oxide on air retrieval.

A modification of a new Arrow prototype catheter was evaluated for its ability to retrieve venous air emboli and for its effect on the success rate of resuscitation from venous air emboli in dogs anesthetized with isoflurane and nitrous oxide (66%) in oxygen. In an additional group of dogs, nitrogen was substituted for nitrous oxide in the inspired gases to determine whether the presence of nitrous oxide (as traditionally used in this model of lethal venous air emboli) increased the apparent amount of gas retrieval or altered the success rate of resuscitation. Dogs were placed in the seated position with the head 90 degrees to the horizontal. The modified Arrow prototype catheter was placed with the proximal orifice just above the superior vena cava-right atrial junction and the distal orifice near the mid-right atrium. Dogs were then given a predetermined lethal dose of air (5 mL/kg) over 30 s through the jugular vein. Attempts to aspirate venous air emboli were begun with the first decrease in expired CO2. The amounts of gas retrieved, expressed as a percent of the injected air, and the incidence of successful resuscitation were compared between groups. In both treatment groups (nitrous oxide and nitrogen), the percent of injected venous air retrieved (73% +/- 13% and 65% +/- 21%, mean value +/- SD, respectively) and success rate of resuscitation (four of six dogs in each group) were significantly increased compared with the control group in which no attempt was made to retrieve injected venous air, and none of the six dogs survived.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1981

[The bacteria stop system of Meierhans-Weber as room air technical alternative to laminar-air-flow and its air hygienic effectiveness].

Statistics of wound infections demonstrate the linear dependence between postoperative wound infection and the quantity of bacteria in the air of operating theatres. In the most extensive examination series we have made as yet with a special work group of DGOT the quantity of bacteria in the air of non air-conditioned operating theatres and such fitted out with different aircleaning systems was determined. Non air-conditioned operating theatres proved so extremely infected that the risk of wound infection cannot be borne any more in the future. Also air-conditioned systems according to DIN 1946/4 with an average of 190 bacteria/m3 are not sufficiently secure for bone and joint surgery. In Switzerland for such operations a value of 10/m3 at the most is admissible. Such equivalents have been attained only with LAF until today. After extensive air tests the so-called "Keimstop"-system by Meierhans and Weber is to be considered the sole system suitable to supplement air conditioning DIN 1946/4. This combination yields the same effect as the expensive LAF systems.

Air Conditioning↗
PubMed1997

[Fungi and bacteria on air filters from heating, ventilation and air-conditioning systems: a method for determination of fungi and bacteria on air filters].

A method was developed for the determination of microorganism concentrations on air filters of HVAC systems, and the influence of different test parameters on the microbiological results was examined by considering various used air filters from several such systems. Microorganisms are detected by shaking air filter samples in fluid, where their concentration is then determined as surface cultures. Since varying the shaking time (30, 60, 90 min) had no influence on the quantitative microorganism determination, a shaking time of 60 minutes was chosen for detection of bacteria, yeasts and moulds. Incubation of blood agar plates either for 4 days at 20 degrees C +/- 2 degrees C or for 2 days at 36 degrees C +/- 1 degree C yielded identical concentrations of bacteria and yeasts. Since results obtained with malt extract agar and Czapek-Dox agar are comparable, one of the two culture media is sufficient for the quantitative determination of moulds on air filters. For statistical evaluation, the inoculation of three parallel agar plates per growth medium was found to be adequate, and the arithmetic mean and the median proved to be equivalent. Investigation on the detection rate showed that, on the average, the method developed demonstrated 80% of the microorganisms detectable on an air filter sample. Thus a simple method is available for quantitative determination of microorganisms on air filters.

Agar↗
PubMed1983

Blood oxygen levels and acid-base status following air exposure in an air-breathing fish, Channa argus: the role of air ventilation.

1. Acute air exposure of an air-breathing fish Channa argus immediately induced hypercapnic acidemia while total CO2 content of blood remained unchanged. Upon reimmersion, paco2 and pHa quickly restored to pre-exposure levels followed by gradual rise of [HCO-3]. 2. Artificial air ventilation of air-exposed fish restored acid-base status and greatly depressed voluntary air ventilatory movements. We conclude that the major cause of acid-base disturbances occurring during air exposure is the reduced air convection.

Acid-Base Equilibrium↗
PubMed1994

Effect of air humidification on the sick building syndrome and perceived indoor air quality in hospitals: a four month longitudinal study.

The sensation of dryness and irritation is essential in the sick building syndrome (SBS), and such symptoms are common in both office and hospital employees. In Scandinavia, the indoor relative humidity in well ventilated buildings is usually in the range 10-35% in winter. The aim of this study was to evaluate the effect of steam air humidification on SBS and perceived air quality during the heating season. The study base consisted of a dynamic population of 104 hospital employees, working in four new and well ventilated geriatric hospital units in southern Sweden. Air humidification raised the relative air humidity to 40-45% in two units during a four months period, whereas the other two units served as controls with relative humidity from 25-35%. Symptoms and perceived indoor air quality were measured before and after the study period by a standardised self administered questionnaire. The technical measurements comprised room temperature, air humidity, static electricity, exhaust air flow, aerosols, microorganisms, and volatile organic compounds in the air. The most pronounced effect of the humidification was a significant decrease of the sensation of air dryness, static electricity, and airway symptoms. After four months of air humidification during the heating season, 24% reported a weekly sensation of dryness in humidified units, compared with 73% in controls. No significant changes in symptoms of SBS or perceived air quality over time were found in the control group. The room temperature in all units was between 21-23 degrees C, and no significant effect of air humidification on the air concentration of aerosols or volatile organic compounds was found. No growth of microorganisms was found in the supply air ducts, and no legionella bacteria were found in the supply water of the humidifier. Air humidification, however, significantly reduced the measured personal exposure to static electricity. It is concluded that air humidification during the heating season in colder climates can decrease symptoms of SBS and perception of dry air.

Adult↗
PubMed1995

Venous air embolism, preservation/reperfusion injury, and the presence of intravascular air collection in human donor livers: a retrospective clinical study.

In human liver transplantation, air embolism is seldom encountered after graft reperfusion. Nevertheless, despite adequate flushing and clamping routines, air emboli have been reported in transesophageal echocardiography (TEE) studies performed during the reperfusion phase. We retrospectively investigated whether air in the donor liver -- as observed with pretransplant magnetic resonance imaging (MRI) -- resulted in clinical air embolism or contributed to preservation/reperfusion injury. Clinical air embolism was assessed by intraoperative hemodynamics and end-tidal CO2 monitoring. Preservation/reperfusion injury was assessed in postoperative biochemical measurements. The outcomes were compared between patients receiving livers containing significant intrahepatic air and patients receiving livers without intrahepatic air. Forty-three livers were studied, seven which had major intrahepatic air and ten of which had no evidence of air collections. Twenty-six livers showed minor amounts of air and were excluded from further study. One patient who received a liver that did not contain intrahepatic air had clinical evidence of air embolism. Clinical air embolism did not appear to be associated with the presence of significant intrahepatic air based upon pretransplant MRI. Intrahepatic air did not seem to affect the amount of preservation/reperfusion injury. Our data indicate that air bubbles in the portal and arterial branches are absorbed during reperfusion and that the majority of intrahepatic air is effectively removed by the specific flushing routines.

Embolism, Air↗
PubMed2002

Effects of humidified and dry air on corneal endothelial cells during vitreal fluid-air exchange.

PURPOSE: To report the immediate anatomic and functional alterations in corneal endothelial cells following use of humidified air and dry air during vitreal fluid-air exchange in rabbits. DESIGN: Experimental study. METHODS: Rabbits undergoing pars plana vitrectomy and lensectomy were perfused with either dry or humidified air during fluid-air exchange for designated durations. Three different experiments were performed. First, control and experimental corneas were examined by scanning electron microscopy (SEM). Second, corneas were stained with Phalloidin-FITC and examined by fluorescein microscopy. Finally, third, transendothelial permeability for carboxyfluorescein was determined using a diffusion chamber. RESULTS: While different from the corneal endothelial cells, those cells exposed to humidified air were less stressed than cells exposed to dry air by SEM. Actin cytoskeleton was found highly disorganized with dry air exposure. Humidified air maintained the normal actin cytoskeleton throughout the 20 minutes of fluid-air exchange. Paracellular carboxyfluorescein leakage was significantly higher in dry air insufflated eyes compared with that of the humidified air after 5, 10, and 20 minutes of fluid-air exchange (P =.002, P =.004, and P =.002, respectively). CONCLUSIONS: Dry air stress during fluid-air exchange causes significant immediate alterations in monolayer appearance, actin cytoskeleton, and barrier function of corneal endothelium in aphakic rabbit eyes. Use of humidified air largely prevents the alterations in monolayer appearance, actin cytoskeleton, and barrier function of corneal endothelial cells.

Actins↗
PubMed2000

Centrifuge modeling of air sparging - a study of air flow through saturated porous media.

The success of air sparging as a remedial technology for treatment of contaminated aquifers is well documented. However, there is no consensus, to date, on the mechanisms that control the flow of injected air through the saturated ground. Currently, only qualitative results from laboratory experiments are available to predict the zone of influence of a sparging well. Given that the patterns of air flow through the soil will ultimately determine the efficiency of an air sparging treatment, it is important to quantify how sparged air travels through a saturated porous medium. The main objective of this research is to develop a model that describes air transport through saturated porous media. This paper presents results from an ongoing study that employs centrifuge modeling to reproduce in situ air sparging conditions. Centrifuge testing is an experimental technique that allows reduced-scale duplication, in the laboratory, of the stresses and pressure distributions encountered in the field. In situ conditions are critical in the development of actual air flow patterns. Experiments are being conducted in a transparent porous medium consisting of crushed borosilicate glass submerged in fluids of matching indices of refraction. Air is observed as it flows through the porous medium at varying gravitational accelerations. Recorded images of experiments allow the determination of flow patterns, breakthrough velocities, and plume shapes as a function of g-level and injection pressure. Results show that air flow patterns vary from fingering, at low g-levels, to pulsing at higher accelerations. Grain and pore size distribution of the porous medium do not exclusively control air flow characteristics. Injector geometry has a definite effect on breakthrough velocities and air plume shapes. Experiments have been conducted to compare the velocity of air flow through the saturated porous medium to that of air in pure liquids. Results show that the velocity of air through the medium is lower than that in the pure fluid, as expected. At high g-levels however, plume breakthrough velocities are proportional to the velocity of the air in the pure fluid.

Acceleration↗
PubMed1994

Effect of air, heliox, and oxygen breathing on air bubbles in aqueous tissues in the rat.

Our purpose was to examine the behavior of air bubbles in three non-lipid tissues (skeletal muscle, tendon, and the anterior chamber of the eye) during breathing of air, helium-oxygen (heliox, 80:20), or oxygen. Air bubbles were injected into skeletal muscle or tendon in rats after decompression from a 1-h air exposure at 3.5 atm abs (355 kPa) or into the anterior chamber of the rat eye without any previous pressure exposure. The bubbles were studied by photomicroscopy at 1 atm abs (101 kPa) during either air breathing or during air breathing followed by heliox or O2 breathing. Muscle: during air breathing, all bubbles initially increased in size for a period of 55-100 min after decompression and then started to shrink. Both heliox and O2 breathing increased the shrinking rate as compared to air. Bubble size decreased more rapidly during O2 than heliox breathing. Tendon: during air breathing, bubble size decreased at a constant rate; in one bubble the decrease was preceded by a small increase. During heliox breathing most bubbles decreased faster than during breathing of air. O2 breathing caused a short-term increase in bubble size in 4 out of 10 bubbles. Otherwise, the shrinkage rate was increased in six bubbles and uninfluenced in four bubbles during breathing of O2. Rat eye: during air breathing all bubbles shrank in the observation period. When heliox breathing was started, all bubbles transiently grew for 10-35 min, after which they began shrinking faster than during air breathing. When O2 breathing was started, five out of seven bubbles initially grew or stopped shrinking for 5-15 min, after which they decreased in size faster than during both air and heliox breathing. We conclude that breathing of either heliox or O2 will cause air bubbles in aqueous tissues to disappear faster than during breathing of air. Since heliox breathing promoted bubble shrinking in both muscle and tendon, gas exchange was probably not primarily limited by extravascular diffusion in these aqueous tissues. The present experiments suggest that heliox breathing at 1 atm abs may not exacerbate limb bends.

Air↗
PubMed1986

Investigations concerning the standardisation of control-investigations of supply-air in air-conditioning systems in hospitals.

In the following investigation, air-germ measurements were conducted--using the Reuter-Centrifugal-Sampler (RCS) and the Sartorius-Sampler MD 3 (SAR), and using standardized nutrient-substratum and breeding conditions--in order to detect differences in the measuring process itself. The aim of the study was to find a standard for routine-measurements in hospitals. A special "Supply-Air-Box" was developed because of the known turbulences during the emission of air from the channel; in order to cut off the interference-factor during the measurements caused by the blending with the room-air. The results of the air-germ measurements showed a sufficient reproducability and a good representation of the results in differing measuring positions with both devices during repeated measurements. A marked difference between the two measuring-devices are the markedly higher CFU-numbers in the measurements using the RCS-device and the resulting higher variability of the single-values. The measurements using the supply-air-box show that--with the usual measuring position immediately in front of the supply-air grille screen or without grille screen at the channel end--a considerable part of room-air is also registered during the determination of the CFU-number because of the existing turbulences. Because of the markedly lower CFU-numbers with this procedure, new recommendations were suggested for the maximal mean CFU-number in the supply-air. Accordingly, not more than 5 CFU/m3 of air should be found with three-step-filtered supply-air in well-maintained installations for the inrestricted utilization of the rooms, and not more than a mean value of 30 CFU/m3 of air with two-step-filtered supply-air.

Air Conditioning↗
PubMed1999

Prevention of visual field defect after macular hole surgery by passing air used for fluid-air exchange through water.

PURPOSE: To evaluate the effect on peripheral visual field defects occurring after macular hole surgery of passing air that is used for fluid-air exchange through water before infusion to the eye. METHODS: We used Goldmann perimetry to measure the visual fields of patients who underwent vitrectomy to manage idiopathic full-thickness macular holes using either room air or humidified air for fluid-air exchange. We retrospectively studied visual fields measured in 39 patients (group 1) who underwent vitrectomy without humidification of air and prospectively studied visual fields measured in 33 patients (group 2) who consecutively underwent vitrectomy with humidified air for fluid-air exchange. RESULTS: In group 1, nine patients (23%) had peripheral visual field defects, most often located in the inferior or inferotemporal quadrant. No patients (0%) in group 2 had a visual field defect after vitrectomy. The difference between groups 1 and 2 in the proportion of patients with visual field defects after vitrectomy was statistically significant (P = .003). CONCLUSIONS: Passing air used for fluid-air exchange through water seems to prevent visual field defects after vitrectomy for macular hole surgery. Visual field defects that occur after room air is used may result from desiccation of the retina by room air.

Aged↗
PubMed1995

Lymphatic air embolism: a new hypothesis regarding the pathogenesis of neonatal systemic air embolism.

Objective. Neonatal systemic air embolism (NSAE) has been thought to result from introduction of air into the pulmonary veins through hypothesized alveolar-capillary fistula. The objective of this paper is to reassess the distribution of intravascular air visualized radiographically in this entity. Based on these data, an alternative theory for the pathogenesis of NSAE is proposed. Materials and methods. Four cases from our institutions and 21 additional reviewable published radiographs of NSAE were evaluated for the presence and location of intravascular air. Nonparametric statistical analysis was performed to determine if the predominance of intravascular air was venous or arterial in location, and to determine the presence or absence of pulmonary interstitial emphysema (PIE), pneumothorax, pneumomediastinum, and pneumopericardium. Results. Isolated systemic venous air was present significantly more often than isolated systemic arterial air (p < 0.0005). In addition, the presence of isolated right-sided cardiac air was found significantly more often than air within left heart chambers alone (p < 0.0005). PIE in patients with NSAE was found to be statistically more prevalent than pneumomediastinum or pneumopericardium, though similar in prevalence to pneumothorax. Conclusion. Our data support the hypothesis that intravascular air in NSAE is predominantly venous in location. PIE was found to be a very common associated finding in NSAE. Based on our current knowledge of pulmonary lymphatics, radiographic anatomy, and the lymphatic location of PIE, we propose that air within the pulmonary lymphatic system (PIE) gains access to the systemic venous system via lymphatic ducts, which results in the clinical entity NSAE. This readily explains the venous predominance of air in NSAE.

Embolism, Air↗
PubMed1998

Can an oxygenator design potentially contribute to air embolism in cardiopulmonary bypass? A novel method for the determination of the air removal capabilities of neonatal membrane oxygenators.

At present, air handling of a membrane oxygenator is generally studied by using an ultrasonic sound bubble counter. However, this is not a quantitative method and it does not give any information on where air was entrapped in the oxygenator and if it eventually was removed through the membrane for gas exchange. The study presented here gives a novel technique for the determination of the air-handling characteristics of a membrane oxygenator. The study aimed at defining not only the amount of air released by the oxygenator, but also the amount of air trapped within the oxygenator and/or removed through the gas exchange membrane. Two neonatal membrane oxygenators without the use of an arterial filter were investigated: the Polystan Microsafe and the Dideco Lilliput. Although the air trap function of both oxygenators when challenged with a bolus of air was similar, the Microsafe obtained this effect mainly by capturing the air in the heat exchanger compartment while the Lilliput did remove a large amount of air through the membrane. In conclusion, the difference in trap function was most striking during continuous infusion of air. Immediate contact with a microporous membrane, avoidance of high velocities within the oxygenator, pressure drop, transit time and construction of the fibre mat all contribute to the air-handling characteristics of a membrane oxygenator.

Air↗