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Report concerning a high-speed drill system powered by compressed air (Air Drill 100) which considerably facilitates the trepanation of a bone window during Toti's operation in conjunction with a combined drill-miller. This instrument provides considerable advantages over traditional electrically operated instruments.
Rats performing on a progressive-ratio schedule that required five additional responses for each successive food reinforcement were administered d-amphetamine. The number of responses required increased until the next ratio was not completed within 15 min. The number of reinforcements obtained during a session increased with increasing doses of d-amphetamine from 0.25 mg/kg to a maximum behavioral effect at 1.0 to 2.0 mg/kg followed by a decline with higher doses. To assess the effects of hyperbaric air on the established d-amphetamine performance, the same doses were administered to rats breathing compressed air at seven times normal atmospheric pressure (7.1 ATA). In the hyperbaric condition the dose-effect function was displaced toward smaller doses such that the maximum behavioral effect was obtained at lower doses than under normal atmospheric pressure; does that produced maximum behavioral effects under normal pressure produced a decline in reinforcements obtained.
This study reports the effects in an animal model of intermittent exposure to hypoxic, hypercapnic gas mixture on pulmonary artery pressure, packed cell volume, ventricular weights, and lung growth. Rats were exposed in chambers for 8 hours to an inspired O2 fraction of 0.10 and an inspired CO2 fraction of 0.06 in alternation with exposure for 16 hours to room air during 21 to 22 days. Control animals were exposed in chambers for 8 hours to compressed air at flow rates similar to those for the test animals, then for 16 hours to room air. Packed cell volume, right ventricular systolic pressure, and the ratio of the right ventricular weight to the weight of the left ventricle plus septum were all significantly greater in the test animals than in the control animals. Lung volume, alveolar number, and surface area were also significantly increased, but only when adjusted for body weight. The increase in right ventricular weight appeared to be due in part to the fact that right ventricular pressure was still increased 16 hours after removal of the hypoxic-hypercapnic gas mixture. The cause of this sustained increase in right ventricular systolic pressure is unclear.
The EEG activity was followed during simulated diving to 20 m depth. Altogether 49 EEG records of 5 min length were taken in 5 divers breathing compressed air in a close system. No significant changes of the EEG could be found during either compression or decompression if only conventional indicators, such as the amplitude of theta activity, were tested. However, a complex "normality ratio," based on multivariate analysis of a normal material, was capable of showing significant impairment of the brain activity during the decompression. The indicator has been designed to reflect the abnormality level rather than the short-lasting EEG changes, the latter being mostly dependent on the alertness fluctuations. The EEG changes associated with alertness fluctuations were assessed separately by means of a specific "alertness indicator" and a prominent alertness increase was found during both compression and decompression phases of the diving experiment.
In 22 adult male albino rats (means = 565 g) it was consistently observed that the time required to anesthetize them with 5 ml of diethyl ether after a hyperbaric exposure of 6 ATA using compressed air decreased depending on the severity of the animals' post-decompression reaction to the compression-decompression exposure. Monitoring the time required to lightly anesthetize adult male rats with diethyl ether to a point of losing the righting reflex after a particular compression-decompression exposure provided an indication of the rats' post-exposure state of health. This technique aided in correctly establishing if a rat developed a degree of decompression sickness that may have otherwise gone unnoticed. The loss of resistance to ether induction as a result of decompression sickness may be related to alterations in the blood-brain barrier, blood perfusion inequities, or changes in cardiopulmonary mechanics due to the presence of gaseous emboli. Rats that survived the compression-decompression exposures showed a marked resistance to ether induction after 24 h of recovery.
BACKGROUND: Exercise induced bronchoconstriction (EIB) is common in elite athletes. Eucapnic voluntary hyperventilation (EVH) is a laboratory test recommended for the identification of EIB in athletes, secondary to a field exercise challenge. Montelukast attenuates EIB, but its protective effect against airway narrowing from EVH has not been investigated. OBJECTIVE: To examine the effectiveness of montelukast after exercise and after EVH. METHODS: A randomised, placebo controlled, double blind, crossover study was performed with 11 physically active EIB positive subjects (eight men, three women; mean (SD) age 22.8 (6.8) years). Six hours before each of the following challenges 10 mg montelukast or placebo was ingested: (a) a six minute, cold air (-3 degrees C) maximal effort work accumulation cycle ergometer exercise; (b) EVH, breathing 5% CO(2) compressed air at 85% maximal voluntary ventilation for six minutes. Spirometry was performed before and 5, 10, and 15 minutes after the challenge. At least 48 hours was observed between challenges. RESULTS: No differences in forced expiratory volume in one second (FEV(1)) were found after the two challenges. Exercise and EVH resulted in falls in FEV(1) of 22.4 (18.0) and 25.6 (16.8) respectively. Falls in FEV(1) after montelukast were less than after placebo (10.6 (10.6) and 14.3 (11.3) after exercise and EVH respectively; p<0.05). Montelukast provided protection against bronchoconstriction (59% and 53%; p<0.05) for eight exercising subjects and 10 EVH subjects; no protection was afforded for three exercising and one EVH challenged subject. CONCLUSIONS: Both exercise and EVH were potent stimuli of airway narrowing. A single dose of montelukast provided reasonable protection in attenuating bronchoconstriction from either exercise or EVH. The similar protection by montelukast suggests that EVH is a suitable laboratory surrogate for EIB evaluation.
Dysbaric osteonecrosis (DON) can occur in humans and sheep after a single hyperbaric air exposure with inadequate decompression. The authors hypothesize that DON does not result from primary embolic or compressive effects of nitrogen bubbles on the osseous vasculature, but by secondary injury to the marrow adipose tissue by rapidly expanding nitrogen gas that triggers local, and possibly systemic, intravascular coagulation. A 28-year-old scallop diver remained at a depth of 92 feet in sea water for 4.5 hours on surface-supplied compressed air. Decompression sickness occurred after a no-stop ascent to the surface, and he died 70 minutes later. Autopsy showed multiple gas bubbles, not only within the great vessels, but in the fatty marrow of his femoral and humeral heads. Lipid and platelet aggregates were found on the surface of marrow bubbles. Fibrin-platelet thrombi were detected within dilated venous sinusoids adjacent to bubbles, and in veins, capillaries, and arterioles. Since pulmonary, renal, and intraosseous (subchondral) fat embolism and fibrin thromboses were observed, it is suggested that injured marrow adipocytes can release liquid fat, thromboplastin, and other vasoactive substances, which conceivably can also play a systemic procoagulant role in triggering disseminated intravascular coagulation and additional DON.
The design of an isolator and its use by an oncology satellite pharmacy for preparing cytotoxic drugs are described. The isolator (Iso Concept, Boulogne, France) is a totally enclosed ventilated biological-safety cabinet of class III polyvinyl chloride (PVC) with positive air pressure, a half-suit with a rotating seal, and attached neoprene gloves. There are three work-stations, one for the half-suit and two along one side of the isolator. The ventilation and air filtration system consists of one entry pipe with a full ventilation-filtration box fitted with one prefilter, one blower, one ball valve, one high-efficiency particulate air (HEPA) filter, one airtight nipple connected to an automatic sterilizer, alarms, and one exhaust pipe protected by a HEPA filter. The air lock consists of a rigid, transparent Plexiglas pass-through. The chamber is sterilized with heated compressed air mixed with 3.5% peracetic acid. Maintenance includes regular changing of gloves and HEPA filters; checking of the integrity of the PVC, half-suit, and gloves; and washing and decontamination procedures. Preparation of cytotoxics is planned in advance with prescription data and manufacturing sheets. In the half-suit, a pharmacy technician reads the label, supervises preparation of the sterile admixture, and writes a label. The operators on the side of the unit read the manufacturing sheet and prepare the dose identified by the label.(ABSTRACT TRUNCATED AT 250 WORDS)
Thirteen guinea pigs, sensitized to ovalbumin, were pretreated with either 1 ml alcoholic onion extract (= 12% v/v ethanol) or 1 ml 12% ethanol solution (control) according to a randomized crossover protocol. Thirty minutes later the animals were challenged twice for 30 sec (n = 5), respectively 60 sec (n = 8), by the inhalation of ovalbumin (1 ml 1% ovalbumin solution nebulized in 10 l air). The intensity of bronchial obstruction was measured by whole body plethysmography using as parameter the amount of 'compressed air'. Oral pretreatment of guinea pigs with onion extract markedly reduced the asthmatic response (p less than 0.02). After onion pretreatment near normal values were obtained after 30 sec challenge (0.04 +/- 0.06 ml compared to 0.24 +/- 0.15 ml in the control) and only slightly increased values after 60 sec challenge (0.16 +/- 0.07 ml compared to 0.33 +/- 0.25 ml in the control).
Air-coupled ultrasonic capacitance transducers operating at frequencies of up to 1 MHz have been employed in a fan-beam configuration for the cross-sectional tomographic imaging of temperature fields and flow fields in air, and the location of solid objects. Separate transmitter and receiver transducers were manufactured using thin polymer dielectric membranes and polished metal backplates, and used to acquire through-transmission data. The fan-beam reconstruction was developed in LabVIEW using a re-bin routine combined with a filtered backprojection algorithm and a difference technique to generate the cross-sectional images. The system was first used to reconstruct images showing the locations of solid objects positioned within the scanned region through interpretation of the arrival time of the transmitted ultrasound. The technique was then extended to image the temperature fields produced in air above a small heat source and the flow field produced by a nozzle connected to a regulated compressed air source. Reconstructed temperatures were within 4% of the measured background air temperature and 9% of the air temperature measured above the heat source. Reconstructed images of the flow field above a small nozzle were also presented, showing that the horizontal component of the flow velocity could be resolved using this method.
INTRODUCTION: The specific structure of enamel fissures of molar teeth requires pre-treatment before a sealant can be effectively applied. MATERIAL AND METHODS: The air abrasion technique is gaining acceptance for this purpose. This study was undertaken to examine the effect of air abrasion on the shape and surface of fissures at three levels (entry, middle part and fundus). RESULTS: Compressed air mixed with aluminum oxide particles resulted in enlargement of the fissure. Microretention sites in the form of pits and hollows were discovered at all levels studied.
An automatic, pneumatically driven autotransfusion system (ATS) was developed because ATSs driven by roller pumps are complicated to set up and require an experienced operator. In this ATS blood is aspirated into a cardiotomy reservoir by means of a constant vacuum applied on that reservoir. Damage to blood cells is reduced by an electronic device that regulates an automatic tubing clamp in the suction line to prevent suction of air along with blood (controlled suction). The blood is reinfused by a diaphragm pump driven by alternating vacuum and compressed air. The frequency of this pump is regulated by a level sensor in the cardiotomy reservoir to maintain a constant preset level. When we tested this automatic ATS in dogs, platelet function and platelet numbers substantially recovered after a dip during an autotransfusion period of 1 hour. Advantages of this ATS are that it causes only minor blood damage, it does not require a specially trained operator, and it is ready to use in every operating room. The diaphragm pump can be made disposable and integrated in the bottom of a cardiotomy reservoir.
For safer and simpler neonatal ECMO management, the authors have been developing an innovative, automatically-controlled ECMO machine using self-regulating blood pumps. The newest model is an air-driven, tube-type blood pump. A pair of blood pumps are placed in parallel and actuated alternately with compressed air. The pump flow is automatically regulated in accordance with hemodynamic changes of the body. The need for a venous reservoir is eliminated because the circuit does not generate excessive negative pressure when there are shortages of draining blood. Therefore, the priming volume of the circuit is only 85 ml. This ECMO apparatus has three driving modes, one of which is a "delay" mode. This enables the pump flow to easily be varied from 10 to 500 ml/min under automatic control, and it can be used when the pump flow is decreased for weaning. This newest ECMO apparatus was clinically used in 3 neonates with severe lung hypoplasia and persistent fetal circulation. The ECMO duration was 139 h to 168 h, and the maximum ECMO flow 71.3 to 109.0 ml/min/kg. Thanks to the self-regulation, intensive observation of the circuit was not necessary during ECMO. Damage to blood cells was less significant, and the use of blood products was only minimal (15.7 ml/kg/day) because a large volume of blood to stabilize the pump performance was not necessary. In conclusion, the automatically-controlled ECMO apparatus worked well without complications by changing the ECMO flow automatically in accordance with hemodynamic changes. This automatic ECMO system required fewer personnel expenditures and was also favorable in terms of hematological findings.
To compare the effects of heliox-driven (He 80:O2 20) to air-driven (N 79:O2 21) beta2-agonist aerosol therapy on pulmonary function tests (PFTs) in patients with asthma, a prospective randomized crossover study was undertaken in the asthma clinic of the university-affiliated county hospital in Houston, TX. Thirty-one patients (22 female, age range 18-44) with clinically stable asthma consented. All patients were studied on two different days with both heliox and air as driving gas, therefore serving as their own controls. The PFTs including forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), maximal mid-expiratory flow rate (FEF(25-75)), and maximal expiratory flow rate (FEFmax) were obtained while breathing ambient air at baseline and 30 min after the bronchodilator treatment. Albuterol sulfate 2.5 mg was nebulized with either heliox or compressed air at 8 L/min for 8 min. When heliox was used as driving agent, additional heliox was delivered via a closed system and no entrainment of external air was allowed. Primary outcome measure was absolute change in FEV1 (deltaFEV1). There were no statistically significant differences in baseline PFTs on the two days of the study. All patients had good bronchodilator response (> or = 12% improvement in FEV1) with either driving gas. The deltaFEV1 after heliox-driven bronchodilator (HDBD) and air-driven bronchodilator (ADBD) were 0.68+/-0.38 L/sec (CI: 0.54-0.82) vs. 0.51+/-0.26 L/sec (CI: 0.42-0.60), respectively (p=0.004). The deltaFEV1 with HDBD was 49+/-90% (range -36% to 433%) more than ADBD. A subgroup analysis showed this was largely due to better response rates in patients with moderate to severe obstruction. There was more improvement in both FVC and FEFmax with HDBD than ADBD (p<0.05). The changes in FEF(25-75) were similar. We conclude that HDBD therapy improves FEV1, FVC, and FEFmax significantly more than ADBD in patients with asthma. Further large randomized studies are needed to better characterize responders and the impact on clinical outcomes.
Recently, air abrasion has experienced a rebirth in restorative dentistry. Originally developed in the late 1940s, the principle of air abrasion is the imparting of kinetic energy to tiny aluminum oxide particles that are projected by a stream of compressed air or gas and expelled from a small nozzle. The force generated by the relatively hard particles striking a relatively hard surface is sufficient to cut into that surface. In the last decade, more than a dozen models of air abrasion units have been introduced into the marketplace and more are on the way. Manufacturers have developed air abrasion instruments that offer a broad range of features, from small table-top units to self-contained systems with compressors, vacuums, and curing lights. The costs range dramatically--from $1,000 to $20,000 or more--depending on the complexity of the features and attachments. Manufacturers make a variety of claims to support the value of this technology to the practicing dentist. A term often used to describe one of the benefits of air abrasion is microdentistry. The claim is that smaller, less invasive tooth preparations may be accomplished using air abrasion than with a traditional bur and air turbine. This may be true in some instances, but it would certainly depend on the operator's experience and ability to visually discern fine detail. Other claims about air abrasion are that it can be used to cut into tooth structure without local anesthesia and that it should be used on all stained grooves or fissures to determine if incipient carious lesions are present. Despite the limited number of clinical studies, the popularity of air abrasion continues to grow. To gain additional insight about these claims and to see what might be on the horizon for this technology, I spoke with three highly respected educators who are recognized for their expertise in air abrasion. What they said should give the reader a better understanding of how air abrasion might augment restorative dentistry procedures and techniques.
A hydrostatic compression device has been designed to study the effects of intermittent or continuous compressive forces on cells by trying to mimic in vivo forces. The model system is composed of two pistons that deliver and release compressed air under control of a motor to form an enclosed tissue culture chamber housing numerous tissues culture dishes. The continuous compressive forces and intermittent compressive forces are within 100-300 KPa and 0-30 KPa respectively. The compressive force is uniform in the system and can also result in the generation of shear forces along the interface between the cells and culture substratum, so the hydrostatic compression device can be used to study the characteristics of in vitro cells loading models.
STATEMENT OF PROBLEM: Many different bonding systems are currently available that may be used to bond composite to base metal alloy. PURPOSE: This study measured and compared bond strengths of composite with a base metal alloy using 8 modern dentin bonding systems. MATERIAL AND METHODS: Base metal alloy buttons were imbedded in acrylic and ground with 120, 400, and 600 grit sandpaper, respectively. Metal surfaces were air abraded for 5 seconds with 50 microm aluminum oxide, washed for 5 seconds under running tap water, then dried with compressed air. Specimens were arbitrarily divided into 8 groups of 10 specimens. Each group was treated with 1 of 8 dentin bonding regimens. A hybrid composite (Herculite) was placed onto the treated metal surface and light polymerized. Specimens were incubated at 37 degrees C in distilled water for 2 hours. Shear bond strengths were measured and the collected data subjected to an ANOVA, followed by multiple t -tests. RESULTS: All-Bond 2 exhibited the highest mean shear bond strength and Panavia 21 with primer had the lowest in the tests conducted. CONCLUSION: All-Bond 2 demonstrated significantly higher shear bond strengths over all materials tested, except 3M Single Bond and Optibond FL. No significant difference was noted between the single component and the multicomponent bonding systems.
Thirty chronic, hypoxaemic patients with a mean arterial oxygen tension (PaO2) of 6.81 kPa (SD 0.56) in air were tested using the Travelair. The study was performed at rest, allowing the patients to breathe in the following conditions: a) compressed air; b) continuous oxygen flow from the concentrator; c) oxygen from the concentrator in demand-valve mode (DV) with an activation time (AT) of 375 ms; d) DV with AT of 750 ms; e) DV with AT of 1,125 ms; f) DV with AT 1,500 ms; and g) continuous oxygen from the hospital outlet at 2 l.min-1. The mean (SD) SaO2% values at each consecutive step were: a) 87.2 (5.0)%; b) 93.0 (3.0)%; c) 93.9 (2.8)%; d) 94.2 (2.5)%; e) 94.0 (2.7)%; f) 94.1 (2.7)%; and g) 94.8 (2.4)%, respectively. Each of the results obtained with DV (b-f) was statistically different from those obtained breathing air (a) or oxygen (g). The mean (SD) respiratory rates at each consecutive step were: a) 21.2 (4.1); b) 21.0 (4.0); c) 21.3 (4.0); d) 21.0 (3.6); e) 20.7 (3.4); f) 21.0 (3.8); and g) 21.2 (3.8) breaths.min-1, respectively. No relationship was found between the mean oxygen saturations and the mean respiratory frequencies of the patients in each condition tested. With the concentrator on demand, the average of the best SaO2% obtained by the patients in whatever of the four DV activation time modes (conditions c-f) was 94.8 (2.4)%, and no statistical difference was detected between this result and the SaO2% obtained with 2 l.min-1 of continuous oxygen.