Deterioration of theatre discipline during total joint replacement--have theatre protocols been abandoned?
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The results of the Medical Research Council trial by Lidwell et al. in 1982 [Lidwell OM, Lowbury EJ, Whyte W et al. Effect of ultraclean air in operating rooms on deep sepsis in the joint after total hip or knee replacement: a randomised study. BMJ 1982; 285: 10-4] showed a decrease in infection rates following joint replacements carried out in ultraclean air theatres. Since then, the orthopaedic community in the UK has relied to a large extent on laminar airflow theatres to control infection following arthroplasty. At the same time, there has been a decline in the emphasis on basic principles and practices of antisepsis based on scientific evidence. We undertook this audit to establish whether published recommendations on theatre discipline were being followed in operating theatres where joint replacements are carried out, in England, Scotland and Wales. Our results show that with improvement in technology involved in clean air theatres, and availability in practice, slackness has crept into theatre protocol. In view of the fact that infection following arthroplasty has not been eliminated or indeed in some cases, maintained at the levels of the Medical Research Council study, we feel that traditional practices should be reintroduced. This study shows that there is pressing need for a set of recommendations on theatre practice for all staff in operating theatres that carry out joint replacements. (+info)
Characterization of indoor particle sources: A study conducted in the metropolitan Boston area.
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An intensive particle monitoring study was conducted in homes in the Boston, Massachusetts, area during the winter and summer of 1996 in an effort to characterize sources of indoor particles. As part of this study, continuous particle size and mass concentration data were collected in four single-family homes, with each home monitored for one or two 6-day periods. Additionally, housing activity and air exchange rate data were collected. Cooking, cleaning, and the movement of people were identified as the most important indoor particle sources in these homes. These sources contributed significantly both to indoor concentrations (indoor-outdoor ratios varied between 2 and 33) and to altered indoor particle size distributions. Cooking, including broiling/baking, toasting, and barbecuing contributed primarily to particulate matter with physical diameters between 0.02 and 0.5 microm [PM((0.02-0.5))], with volume median diameters of between 0.13 and 0.25 microm. Sources of particulate matter with aerodynamic diameters between 0.7 and 10 microm [PM((0.7-10))] included sauteing, cleaning (vacuuming, dusting, and sweeping), and movement of people, with volume median diameters of between 3 and 4.3 microm. Frying was associated with particles from both PM((0.02-0.5)) and PM((0.7-10)). Air exchange rates ranged between 0.12 and 24.3 exchanges/hr and had significant impact on indoor particle levels and size distributions. Low air exchange rates (< 1 exchange/hr) resulted in longer air residence times and more time for particle concentrations from indoor sources to increase. When air exchange rates were higher (> 1 exchange/hr), the impact of indoor sources was less pronounced, as indoor particle concentrations tracked outdoor levels more closely. (+info)
Mass carbon monoxide poisoning.
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The largest occurrence of carbon monoxide poisoning in Britain demonstrates the potential for mass accidental poisoning. It emphasises the need for strict public health controls and the importance of good liaison between emergency services to ensure that such events are quickly recognised and that the necessary resources are organised. (+info)
Laboratory evaluation of welder's exposure and efficiency of air duct ventilation for welding work in a confined space.
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CO2 arc welding in a confined space was simulated in a laboratory by manipulating a welding robot which worked in a small chamber to experimentally evaluate the welder's exposure to welding fumes, ozone and carbon monoxide (CO). The effects of the welding arc on the air temperature rise and oxygen (O2) concentration in the chamber were also investigated. The measuring points for these items were located in the presumed breathing zone of a welder in a confined space. The time averaged concentrations of welding fumes, ozone and CO during the arcing time were 83.55 mg/m3, 0.203 ppm and 0.006%, respectively, at a welding current of 120A-200A. These results suggest serious exposure of a welder who operates in a confined space. Air temperature in the chamber rose remarkably due to the arc heat and the increase in the welding current. No clear decrease in the O2 concentration in the chamber was recognized during this welding operation. A model of air duct ventilation was constructed in the small chamber to investigate the strategy of effective ventilation for hazardous welding contaminants in a confined space. With this model we examined ventilation efficiency with a flow rate of 1.08-1.80 m3/min (ventilation rate for 0.40-0.67 air exchanges per minute) in the chamber, and proved that the exposure level was not drastically reduced during arcing time by this air duct ventilation, but the residual contaminants were rapidly exhausted after the welding operation. (+info)
Measurement and reduction of occupational exposure to inhaled anaesthetics.
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The occupational exposure of hospital staff to inhaled anaesthetics was investigated using a personal sampling device that provides a measure of the average concentrations breathed by a person over a period of time, as distinct from the spot sampling in the general environment. The anaesthetist's average exposure to nitrous oxide and halothane during complete operating sessions was twice that expected from simple dilution of the escaping gases by the operating room ventilation. The sampling technique was also used to evaluate the effect of (1) redirection of the waste gas outflow; (2) active scavenging connected to the piped vacuum system. Short-period studies under controlled conditions in the operating theatres and anaesthesia induction rooms showed that the anaesthetist's exposure could be reduced two- or fourfold by redirecting the outflow and another four- to sixfold by active scavenging. Exposures during complete operating sessions were reduced two- to seven-fold by scavenging. (+info)
Influence of evaporation and solvent mixtures on the absorption of toluene and n-butanol in human skin in vitro.
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The influence of forced ventilation on the percutaneous absorption of butanol and toluene was studied in vitro. Human skin was exposed to the neat solvents and the solvents in binary mixtures with each other and in ternary mixtures with chloroform:methanol. The exposure was either unventilated or ventilated with various flow rates. At the ventilated exposure the skin absorption of all solvents and solvent mixtures was markedly reduced compared to unventilated exposure. Exposure with solvent mixtures increased the amounts of solvent absorbed as well as absorption rates. The absorption of the butanol component was most influenced. Increase in absorption was 11 to 9 times depending on whether toluene or chloroform/methanol was cosolvent. There was also an interindividual variation of absorption rate, varying with a factor of 3.5 for toluene and 4.3 for n-butanol within the 3 skin donors used. Skin absorption of volatile organic solvents at continuous ventilated conditions is related to their volatility and to the ventilation rate.A sufficient workplace ventilation is an important occupational hygienic measure not only to reduce exposure via respiration but to reduce absorption via the skin of volatile compounds as well. (+info)
Required response time for variable air volume fume hood controllers.
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This paper describes results from tests made with the aim of investigating how quickly the exhaust air flow rate through fume hoods needs to be controlled in order to prevent contaminants from leaking out of the fume hood and putting the safety of the laboratory personnel at risk. The measurements were made on a laboratory fume hood in a chemical laboratory. There were no other fume hoods in the laboratory, and the measurements were made without interference from persons entering or leaving the laboratory or walking about in it. A tracer gas method was used with the concentration of dinitrogen oxide (N(2)O) being recorded by a Foxboro Miran 101 infra-red gas analyser. In parallel with the tracer gas measurements, the air velocity through the face opening was also measured, as was the control signal to the damper controlling the air flow rate. The measurements show an increased outward leakage of tracer gas from the fume hood if the air flow rate is not re-established within 1-2 s after the sash is opened. If the delay exceeds 3 s the safety function is temporarily defeated. The measurements were made under virtually ideal conditions. Under more typical conditions, the fume hood could be exposed to various other external perturbations, which means that the control system should re-establish the correct exhaust flow more quickly than indicated by the measurement results obtained under these almost ideal conditions. (+info)
A 37-year-old mechanic with multiple chemical sensitivities.
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A 37-year-old heating, ventilation, and air-conditioning mechanic developed respiratory, musculoskeletal, and central nervous system symptoms associated with a variety of odorous environmental chemicals. Organic disease was not evident, but the patient was distressed by these symptoms and was at risk for becoming disabled by them. His symptoms fit broadly into the condition recognized as multiple chemical sensitivity. Multiple chemical sensitivity is a diagnostic term for a group of symptoms without demonstrated organic basis. The symptoms are characteristic of dysfunction in multiple organ systems, they increase and decrease according to exposure to low levels of chemical agents in the patient's environment, and they sometimes occur after a distinct environmental change or insult such as an industrial accident or remodeling. Although traditional medical organizations have not agreed on a definition for this syndrome, it is being increasingly recognized and makes up an increasing percentage of the caseload at occupational and environmental medicine clinics. Although there is often dispute about whether the symptoms have a functional or organic basis, an informed approach to evaluation, diagnosis, and management and a careful assessment of impairment, disability, and work relatedness are necessary. Careful exclusion of organic causes is critical, and this should be followed by a judicious approach to coping with symptoms. (+info)