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PubMed2004

A portable automated system for trace gas sampling in the field and stable isotope analysis in the laboratory.

A computer-controllable mobile system is presented which enables the automatic collection of 33 air samples in the field and the subsequent analysis for delta13C and delta18O stable isotope ratios of a carbon-containing trace gas in the laboratory, e.g. CO2, CO or CH4. The system includes a manifold gas source input for profile sampling and an infrared gas analyzer for in situ CO2 concentration measurements. Measurements of delta13C and delta18O of all 33 samples can run unattended and take less than six hours for CO2. Laboratory tests with three gases (compressed air with different pCO2 and stable isotope compositions) showed a measurement precision of 0.03 per thousand for delta13C and 0.02 per thousand for delta18O of CO2 (standard error (SE), n = 11). A field test of our system, in which 66 air samples were collected within a 24-hour period above grassland, showed a correlation of 0.99 (r2) between the inverse of pCO2 and delta13C of CO2. Storage of samples until analysis is possible for about 1 week; this can be an important factor for sampling in remote areas. A wider range of applications in the field is open with our system, since sampling and analysis of CO and CH4 for stable isotope composition is also possible. Samples of compressed air had a measurement precision (SE, n = 33) of 0.03 per thousand for delta13C and of 0.04 per thousand for delta18O on CO and of 0.07 per thousand for delta13C on CH4. Our system should therefore further facilitate research of trace gases in the context of the carbon cycle in the field, and opens many other possible applications with carbon- and possibly non-carbon-containing trace gases.

Carbon Dioxide↗
PubMed2006

Ability of quantitative light-induced fluorescence (QLF) to assess the activity of white spot lesions during dehydration.

PURPOSE: To determine the ability of QLF to assess the activity of white spots using visual examination (VE) as the gold standard. METHODS: Thirty-four specimens were prepared from extracted human permanent posterior teeth presenting natural white spots on the approximal surface. Fluorescence images were acquired at 1-second intervals for the first 10 seconds and every 5 seconds thereafter to 45 seconds. During image acquisition, specimens were dehydrated with compressed air. QLF variables of fluorescence loss (deltaF [%]), lesion size (S [mm2]), and deltaQ (deltaFxS [% x mm2]), were determined. Change in QLF variables per second (deltaQLF(D): deltaF(D), deltaS(D), deltaQ(D)) was determined using the following equation: (subsequent QLF-variables--baseline QLF-variables)/dehydration time. Five experienced dentists independently conducted VE under standardized conditions using a dental unit's light, compressed air, with an explorer, used only to check surface structure. Prior to VE, examiners had participated in a half-day training seminar on VE. After drying the specimens, examiners graded the lesions according to dullness of surface, roughness and presence of microcavitation. Agreement by at least three of them determined the activity status of lesions. RESULTS: deltaQLF(D) values of Active white spot group (n = 7) were compared with those of Inactive white spot group (n = 27) using a two-sample t-test. In general, the active group presented larger values of deltaQLF(D) than the inactive group; however, there were no differences in deltaF(D) and deltaS(D). There were significant differences in deltaQ(D) up to 6 seconds of dehydration (P < 0.05), and no differences after 7 seconds. The results suggest that deltaQ(D) can differentiate between active and inactive white spot lesions using QLF during the first few seconds of dehydration.

Air↗
PubMed1976

Brain stimulation in rats exposed to hyperbaric environments.

Six rats were trained to make an operant response to receive brief trains of electrical current to the lateral hypothalamus (self-stimulation). All animals were then randomly exposed to pressures of 4.03, 5.51, 7.06, or 10.1 ATA breathing either compressed air or N2-O2 and 13.1 ATA (N2-O2 only). When the subjects breathed air at pressures of 7.06 and 10.1 ATA, rate of self-stimulation decreased by 32 and 43%, respectively. No differences were observed in rate of response at any pressure when the animals breathed N2-O2 with the partial pressure of oxygen maintained at 0.2 ATA. When an oxygen-nitrogen mixture was breathed at 3 ATA in which the PO2 was similar to compressed air at 10.1 ATA, self-stimulation rate was decreased by 40%; this suggests that PO2 is a critical variable influencing behavior mediated by brain stimulation. Results are discussed in terms of the use of self-stimulation as one tool for better understanding the neuronal mechanisms of behavior as they relate to breathing-gas mixtures at increased pressures.

Analysis of Variance↗
PubMed1981

Early experience with a vertical spinning-disc nebuliser.

A new device for the administration of bronchodilators to asthmatics by nebulisation has been developed. Nebuliser therapy, in many patients more effective than other forms of drug delivery, has been limited by the need to provide patients with units driven by compressed air. Solutions can be nebulised by contact with a rapidly spinning horizontal disc. Adaptation of this method to a small nebuliser for clinical use is difficult, since a constant delivery of fluid the centre of the disc is necessary. The problem has been overcome in the new device in which the disc spins vertically in a reservoir. The performance of the prototype device was compared with that of a conventional compressed air nebuliser. The improvement is spirometry values of 8 asthmatic patients was similar for both nebulisers.

Adult↗
PubMed2003

[Central nervous system involvement in patients with decompression illness].

Dysbarism or decompression illness (DCI), a general term applied to all pathological changes secondary to altered environmental pressure, has two forms decompression sickness (DCS) and arterial gas embolism (AGE) after pulmonary barotrauma. Cerebral and spinal disorders have been symptomatically categorized as AGE and DCS, respectively. Magnetic resonance images (MRIs) of divers with DCI showed multiple cerebral infarction in the terminal and border zones of the brain arteries. In addition, there were no differences between MRI findings for compressed air and breath-hold divers. Although the pathogenesis of the brain is not well understood, we propose that arterialized bubbles passing through the lungs and heart involved the brain. From the mechanisms of bubble formation, however, this disorder has been classified as DCS. We propose that there is a difference between clinical and mechanical diagnoses in the criteria of brain DCI. In contrast to brain injury, the spinal cord is involved only in compressed air divers, and is caused by disturbed venous circulation due to bubbles in the epidural space. The best approach to prevent diving accidents is to make known the problems for professional and amateur divers.

Central Nervous System↗
PubMedDate not supplied

[Asbestos risk in the textile industry: braking systems on machinery used until the 1990's].

BACKGROUND: We recently described asbestos risk in the non-asbestos textile industry as the result of fibre dispersion from ceilings, pipe insulation and machines. OBJECTIVES: The widespread use of brakes with asbestos linings on the machines as well as other functional details were considered for a proper evaluation of their role in producing atmospheric pollution METHODS: All the information was collected on the basis of the personal technical experience of two of the Authors and by direct observation of the machines. RESULTS: All the textile machines (ring spinning, twisting, warping, winding, looms) used until the 1990's were without exception equipped with asbestos-lined mechanical brakes. The heavy action required produced relatively rapid wear of the linings and the dust produced was spread into the atmosphere by the continuous action of the "travelling blowing cleaners" and by the daily cleaning of the machines using compressed air at the end of the shift: violent air blowing undoubtedly caused redispersion of the fine dust from the brakes and also acted as a mechanical grinder on the bundles that sedimented on the machines from the ceilings and pipes, producing more ultrathin respirable fibres. CONCLUSIONS: the contribution of textile machinery to atmospheric pollution by asbestos fibres was significant and due both to the widespread use of brakes with asbestos-containing materials and to the continuous action on the machines of compressed air blowers. Asbestos pollution was certainly high in all the factories so that in the near future still further mesothelioma cases among ex-workers are to be expected.

Air Pollutants, Occupational↗
PubMed1984

Bone necrosis due to decompression.

Death of areas of long bone has been known to be associated with work in compressed air and diving for many years. Detection and diagnosis require specialist knowledge, but familiarity with the condition has increased markedly over the last 20 years. Most of it is symptomless and causes no disability, but if areas adjacent to the joint surfaces of the upper end of the humerus and the upper end of the femur are affected, the joint may be seriously damaged and disability ensue. This problem has been defined by surveys of groups of workers using compressed air and divers in an attempt to establish prevalence. In general the more diving undertaken and the deeper the dives, the more probability there is of acquiring bone damage. The commonest area to be affected is the lower end of the femur, but the knee joint is never involved. The cause of bone damage is far from clear. None of the various explanations that have been offered are satisfactory, but research continues into the problem both in humans and in animals, particularly the miniature pig. At present it is difficult to quantify the risk taken by commercial divers in relation to changing technology either in terms of depth or duration of pressure.

Adult↗
PubMed1984

In vitro elevation of red blood cell 2,3-diphosphoglycerate with fructose, phosphate, and methylene blue.

2,3-Diphosphoglycerate (2,3-DPG) is an important regulator of hemoglobin oxygen affinity and thus can theoretically affect tissue oxygenation. Marked stimulation of DPG with substances that would likely be well tolerated by humans has not been reported previously. In order to achieve such stimulation, we investigated (n = 102) the effect of various combinations of fructose (2.8-11.1 mM) and sodium phosphate (1.0-130.0 mM) on 2,3-DPG production by perfusing fresh human blood in dialysis tubing, 37 degrees C, pH 7.15-7.70, with the appropriate solutions and with compressed air or 100% O2 for up to 6 hours. The DPG increased significantly with fructose/phosphate incubations for 6 hours. At pH greater than 7.35 the average increase was 25%; at pH less than 7.35, 12%; PO4 greater than 6 mM + pH greater than 7.35 yielded the highest changes, 28%. Methylene blue 2.5-7.5 microM + PO4 greater than 2.5 mM + pH greater than 7.35 yielded similar results. Glucose + PO4 showed no effect on DPG. Results were comparable at all fructose levels either with compressed air or 100% O2. Significant elevations in 2,3-DPG were also noted at 4 hours but were of lesser magnitude. In conclusion, significant elevations in 2,3-DPG can be achieved by incubating whole blood with fructose/phosphate solutions or with methylene blue and phosphate for 4-6 hours. It should be possible to adapt these solutions for human use to raise 2,3-DPG. The potential physiologic value of rightward shifts in hemoglobin oxygen affinity can then be tested under appropriate conditions.

Adult↗
PubMed2000

Double-blind acute clonazepam vs. placebo in carbon dioxide-induced panic attacks.

The inhalation of 35% carbon dioxide has consistently been shown to provoke panic attacks in panic disorder patients. We aim to determine if an acute dose of clonazepam (2 mg) attenuates the panic attacks induced by an inhalation of 35% carbon dioxide in panic disorder. Twenty-two panic disorder patients who had been drug-free for 1 week participated in a carbon dioxide challenge test 1 h after a dose of either 2 mg of clonazepam or placebo with a randomized double-blind method. Also in a double-blind design during the tests the patients inhaled either atmospheric compressed air ('placebo control') or the carbon dioxide mixture. All patients participated in both tests which were done with a 20-min interval. Immediately before and after the inhalation, the anxiety levels and the symptoms of panic were always assessed. In the clonazepam group (n=11) two patients (18.2%) had a mild panic attack and in the placebo group (n=11) nine patients (81.8%) had a moderate to severe panic attack in the CO(2) challenge test. No patient had panic attacks during inhalation of atmospheric compressed air although anticipatory anxiety levels tended to be higher than in the CO(2) tests. After the CO(2) test anxiety levels were significantly greater in the CO(2) group (three-way ANOVA with Geisser-Greenhouse adjustments, F(31.92,1.86)=17.15, d.f.=7, P=0.013). Although a small sample was studied, the findings suggest the efficacy of an acute dose of clonazepam in attenuating panic attacks induced by carbon dioxide inhalation.

Administration, Inhalation↗
PubMed1995

Physical properties of aerosolized immunoglobulin for inhalation therapy.

Animal studies suggest that passive immunization by intratracheal application of gammaglobulins may succeed in treating small children and infants with severe lower respiratory tract infection caused by respiratory syncytial virus (RSV). Since proteins foam easily when stirred up or used with compressed air, the feasibility of nebulization of the immunoglobulin solution (IVIG, Sandoglobulin) had to be tested. The therapeutic effect of a drug delivered via inhalation is proportional to the mass of aerosol deposited in the lungs. For a fixed breathing pattern, the amount deposited per unit of time in the thoracic region depends on mass flow rate and distribution of aerosol mass by droplet size. Both these variables were determined in relation to the weight concentration (osmolality), viscosity, and surface tension of the IVIG solution for four compressed air nebulizers. The mass flow rate of the spray decreases as the weight concentration of the solution increases, but droplet size distribution does not change. If the IVIG solution does not exceed 5% and the airflow rate is 6 L/min, a mass flow of about 150 mg to 250 mg (7.5 to 12.5 mg IVIG) per minute is obtained, depending on the physical characteristics of the nebulizer used. Low mass median diameter of about 2 microns and a mass distribution with a high percentage of the droplets below 6 microns will allow optimum intrapulmonary deposition in infants.

Aerosols↗
PubMed1985

Pulmonary deposition of aerosols by different mechanical devices.

With a new method for easy labeling of beta 2-agonists we measured intra- and extrapulmonary aerosol deposition after the administration of a bolus from a metered-dose inhaler at residual volume (RV) inhaling after a pause of 2 s and after immediate administration into the inspiratory flow at functional residual capacity (FRC). Immediate administration during a slow inspiratory vital capacity maneuver gives the highest intrapulmonary deposition (30-40%). Compressed air and ultrasonic nebulizers with a particle distribution pattern of 2-5 micron aerodynamic mass median diameter (AMMD) allow in normal subjects to achieve an intrapulmonary deposition of 30-60% during standardized tidal breathing at rest, the magnitude of the deposition depending mainly on each subject's larynx geometry. The outlet system leads to different deposition patterns in aerosol generators with the same AMMD. Many commercially available aerosol generators do not fulfill the criteria for any intrapulmonary aerosol deposition. For drug administration into the lungs, condensation aerosol generators ('steam boiler nebulizers') are useless as well as compressed-air, ultrasonic and steam driven nebulizers with a particle size of more than 10 micron AMMD.

Adrenergic beta-Agonists↗
PubMed1989

Supplemental oxygen and quality of sleep in patients with chronic obstructive lung disease.

The hypothesis that supplemental oxygen could improve the quality of sleep was tested in 23 consecutive patients (14 male, nine female; age 42-74 years) with chronic obstructive lung disease (mean (SD) FEV1 0.81 (0.32) litre, FEV1/FVC 37% (12%). Patients breathed compressed air or supplemental oxygen via nasal cannulas on consecutive nights in a randomised, double blind, crossover trial. Quality of sleep was assessed by questionnaire and by electroencephalographic sleep staging. The study had a power of 80% to detect, at the 0.05 level, a 20% improvement in total sleep time. Seventeen patients slept for two nights in the laboratory. Oxygenation during sleep was improved by oxygen administration, but there was no improvement in quality of sleep. There was an acclimatisation effect with better sleep on the second night. Six patients spent an additional acclimatisation night in the laboratory as well as the two study nights. There was no difference in sleep quality between the second and third nights or between the compressed air and the oxygen nights in these patients. Subgroups of patients with an arterial carbon dioxide tension of over 43 mm Hg (5.7 kPa) (n = 12) and arterial oxygen saturation of less than 90% (n = 11) while awake did not show any improvement in quality of sleep on the oxygen night. It is concluded that supplemental oxygen improves nocturnal oxygenation but does not immediately improve the quality of sleep in the laboratory in patients with chronic obstructive lung disease.

Adult↗
PubMed1996

The distribution of limb pain in decompression sickness.

BACKGROUND: For many years there has been a widely held but largely unsubstantiated belief that pain in the upper limb in decompression sickness (DCS) is associated with bounce diving, whereas compressed air workers, saturation divers and high altitude aviators are more susceptible to involvement of the lower limbs. HYPOTHESIS: The hypothesis of counter current exchange of inert gas, modulated by changes in tissue temperature, has been evaluated as a possible mechanism to explain the reported distribution of limb pain in DCS. METHODS: An extensive review of over 19,000 cases of limb pain decompression illness has been undertaken from case reports stored in the diving accident database at the Institute of Naval Medicine, in the published literature, and from unpublished clinical and experimental reports. RESULTS: There was a predominance of upper limb involvement in bounce divers and, in contrast to traditional teaching, in aviators. By contrast, the lower limbs were more commonly involved in compressed air workers and saturation divers. CONCLUSION: Each of the occupational exposures has been discussed individually with reference to counter-current exchange and other factors as potential influences on the distribution of disease. We conclude that counter-current exchange of inert gas may be implicated in the distribution of limb pain in DCS.

Acid-Base Equilibrium↗
PubMed1992

Lung diffusing capacity in a hyperbaric environment: assessment by a rebreathing technique.

A rebreathing method was developed for measuring diffusing lung capacity for carbon monoxide (DLCO) in a hyperbaric environment. Twenty two professional naval divers with normal lung function were included in the study. Significant correlations were found between rebreathing and single breath measurements for DLCO (r = 0.94; p less than 0.001; standard error of the estimate (SEE) = 0.66), alveolar volume (VA) (r = 0.79; p less than 0.005; SEE = 0.51), and DLCO/VA (r = 0.83; p less than 0.001; SEE = 0.11). In 17 divers, rebreathing DLCO (DLCOrb) was also measured at 20 minutes pre-dive, during the first decompression stop of the dive to 45 m for 25 minutes, and at 10 minutes post-dive. Compressed air diving was performed in a dry walk-in chamber and the United States Navy decompression table was followed. The pressure induced decrease in the rate of CO binding to haemoglobin was adjusted to normobaric conditions using a theoretical approach. Also, the presence of venous bubbles post-dive was detected by precordial doppler monitoring. A biphasic change in DLCO was noted: initially, DLCO was increased during the dive (p less than 0.005); this was followed by a post-dive decrease; DLCO/VA changed in a similar manner, as VA was only slightly altered. Only a small post-dive precordial doppler bubble grade was found. In conclusion, rebreathing DLCO measurement is a useful respiratory function test in the hyperbaric environment. It appears that an increase in D(L)CO during the compressed air dive is related predominantly to increased pulmonary capillary blood volume caused by increased negativity of the pleural pressure, hyperoxic pulmonary vasodilatation, and cardiorespiratory centralisation of the blood. The decrease in D(L)CO post-dive was only partially related to the presence of the venous bubbles detectable by doppler.

Adult↗
PubMed1999

The indigenous fisherman divers of Thailand: in-water recompression.

BACKGROUND: The Urak Lawoi, part of the Sea Gypsies of Thailand, have been diving using surface-supplied compressed air for more than 30 years. Their dive sites range from one hour to several days from their villages. Similar to other indigenous fisherman divers, the Urak Lawoi suffer from a high incidence of decompression illness. Their methods of in-water recompression were investigated. METHODS: In December 1998, available divers in two Urak Lawoi villages were asked if they had ever been treated using in-water recompression following decompression illness. If the divers responded positively, a questionnaire-based interview was carried out. Divers were asked to recall the cause of the accident, their diving patterns of the day, the parts of the body affected, the depths and times of in-water recompression and whether the problems were resolved as a direct result of this action. RESULTS: Eleven divers, aged 19-52, were interviewed. Causal factors listed by the divers included diving pattern 55% (6/11), rapid ascent 27% (3/11), and equipment failure 18% (2/11). Divers were recompressed in water using surface-supplied compressed air. The time between surfacing from the accident-related dive and being put back in the water ranged from immediately to 60 minutes. Depth and duration of in-water recompression ranged from 4 to 30 meters and 5 to 120 minutes. Outcomes reported by the divers were: improved or resolved at depth with no return of symptoms at surface in 64% (7/11), improved or resolved at depth with a return of symptoms at surface in 18 (2/11), and not resolved at depth in 18% (2/11). DISCUSSION: Health-care workers in the villages may be able to provide basic first aid but, for some villages, a medical doctor may be as much as 10 hours away and a recompression facility as far as 16 hours in good weathier. In-water recompression has, within the diving population, proved to be an appropriate first-aid measure for decompression illness. A future project activity will develop consensus guidelines for determining under what circumstances in-water recompression using surface-supplied air should be carried out and identify appropriate methods that the Urak Lawoi can apply.

Adult↗
PubMedDate not supplied

Effects of limited paternal exposure to xenobiotic agents on the development of progeny.

This report represents a series of investigations of the postnatal functional sequelae of paternal exposure to opioids and other xenobiotic agents. In separate studies, young adult male mice were exposed to (1) morphine; (2) levorphanol or its nonanalgesic isomer dextrorphan; or (3) 80% nitrous oxide/20% oxygen. Males (5-8/group) were injected twice daily for 5 1/2 or 8 1/2 days with opioids or saline, or received a single 4 hour inhalation exposure to nitrous oxide/oxygen or compressed air. At 6-8 1/2 days post-treatment, each male was housed with 3 drug-naive nulliparous females. With the exception of birth weights of litters, no alterations in reproductive indices were observed. Changes in reproductive endocrine parameters included marked attenuation of serum luteinizing hormone response to castration in both young adult (8 week) and older (18 week) F1 morphine offspring, when compared with saline-derived groups. The morphine progeny showed decrements in body weight and delayed onset of maturational indices through four generations of selective inbreeding. Similar developmental delays occurred in F1 offspring originating from paternal levorphanol, dextrorphan and nitrous oxide groups, when compared with their respective controls. Behavioral study of F1 offspring revealed alterations in: water maze performance and learning, if preceded by unavoidable footshock, in morphine offspring at 8 and 18 weeks; aberrant swim patterns in both levorphanol and dextrorphan progeny at 6 1/2 and 8 1/2 weeks. Nitrous oxide progeny showed a blunting of hypothermic response to pharmacologic challenge at 16 weeks, in comparison to compressed air controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

[Nitric oxide delivery through ventilator and its toxic oxidative product nitrogen dioxide].

OBJECTIVE: To observe nitric oxide(NO) delivery through mechanically ventilator. NO is rapidly converted to nitrogen dioxide(NO2)in oxygen(O2) environments. METHODS: NO(800 ppm)was blended with compressed air, delivered to the high-pressure air inlet of a Siemens Servo 900C or VIP BIRD ventilator, and used to ventilator as a test lung. The ventilator settings were varied, minute ventilation (VE)from 2 to 6 L/min, inspired O2 fraction(FiO2)from 0.25 to 0.65, and NO concentration from 10 to 80 ppm. The inspiratory gas mixture was sampled just at the outlet port of ventilator. NO and NO2 were measured both by hemiluminescence and electro-chemical fuel cell technique. RESULTS: No NO was detected during any trial with VE 5 or 6 L/min., with FiO2 0.35 or 0.25, with NO 20 or 10 ppm. Low VE and low NO, NO2 values were greater with Servo 900C ventilator than with VIP BIRD ventilator at similar settings High VE and low NO or low VE and high NO, NO2 values were similar with both ventilators. High VE and high NO, NO2 values were greater with VIP BIRD ventilator than with Servo 900C ventilator. At same VE, NO2 values increased with increased FiO2 and NO. (NO2) = 0.0607 (NO)- 0.6604 VE + 7.004 FiO2, R2 = 0.7649 with Servo 900C ventilator,(NO2) = 0.0929(NO)- 0.1296 VE + 7.9360 FiO2, R2 = 0.8687 with VIP BIRD ventilator. CONCLUSIONS: NO(800 ppm) was blended with compressed air, delivered to the high-pressure air inlet of a Siemens Servo 900C or VIP BIRD ventilator is a portable, accurate, and adaptable system to deliver NO. During NO inhalation, VIP BIRD ventilator is more adaptable while low VE. Servo 900C ventilator is more adaptable while high VE.

Humans↗
PubMed2001

Effects of ambient cold and depth on lung function in humans after a single scuba dive.

This study evaluated the subacute respiratory effects of diving, to try to separate the effects of ambient temperature from those of depth. In the first experiment 10 healthy men made a compressed-air dive to 50 m that exposed them to cold. They were compared with 10 matched control subjects who underwent the same dive profile but were exposed to a comfortable temperature. In the second experiment 16 healthy subjects made randomized cold dives to both 50 m and 10 m. Pulmonary function tests were made before, after 1 h, and 24 h after the dives. In the first experiment there was an increase in residual volume (P < 0.05) and a decrease in forced expiratory volume at 1 s (FEV1), in forced vital capacity (FVC) and in mid-expiratory flow at 75% of FVC (MEF75) 1 h after the cold dives (P < 0.05). In the second experiment significant increases in specific airways resistance (sR(AW)) (P < 0.05) and decreases in FEV1 (P<0.01), in MEF75 (P<0.05), and in mid-expiratory flow at 25% of FVC (P<0.05), were obtained after the 50 m-dives, whereas SR(AW) increased after the 10 m-dives (P<0.05). The respiratory pattern observed 1 h after cold dives to 50 m indicated airway narrowing. The changes after cold dives to 10 m, however, were of minor magnitude. Both cold and depth seemed to contribute to the adverse effects of a single compressed-air dive on pulmonary function.

Adult↗