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S Hetland

Publications and source records attributed to S Hetland.

13 recordsLinked to original sources
PubMed2001

Chemical speciation and sequential extraction of Mn in workroom aerosols: analytical methodology and results from a field study in Mn alloy plants.

Workers in the Mn alloy producing industry are exposed to aerosols containing a variety of Mn compounds (MnO, MnO,, Mn2O3, Mn3O4, FeMn and SiMn). This paper reports a novel four-step chemical speciation/ fractionation procedure developed for characterisation of workroom aerosols collected in Mn alloy producing plants. The following components of the aerosol have been quantified: "water soluble" Mn dissolved in 0.01 M ammonium acetate: Mn0 and Mn2+ dissolved in 25% acetic acid; Mn3+ and Mn4+ dissolved in 0.5%) hydroxylamine hydrochloride in 25%) acetic acid; and "insoluble" Mn digested in aqua regia and hydrofluoric acid. Dissolution of pure Mn compounds with well-defined stoichiometries were essentially complete in the respective leaching steps with detectable amounts of < 1% in others. Recoveries of a mixed quality control sample were also acceptable in the range 92-97% for the different oxidation states. The levels measured in the inhalable and respirable fractions in three Mn alloy producing plants were approximately 300 and 35 microg m(-3) of total Mn, respectively. The most obvious feature of the speciation results is that none of the work areas is characterised by a single Mn contaminant. The predominant oxidation states in the inhalable aerosol fraction are Mn0 and Mn2+ independent of job functions/departments. The occurrence of insoluble Mn compounds in both the inhalable and respirable aerosol fractions is significantly higher during production of SiMn.

Aerosols↗
PubMed2000

Bradycardia and asystolic cardiac arrest during spinal anaesthesia: a report of five cases.

Sudden, severe bradycardia/asystolic cardiac arrest are considered infrequent, but are certainly the most serious complications of spinal anaesthesia. We report four cases of primary asystole and one of severe bradycardia in young to middle-aged, healthy patients scheduled for minor surgery at the day surgery unit. Bradycardia/asystole were not related to respiratory depression or hypoxaemia/hypercarbia; they occurred at different time intervals after the onset of spinal anaesthesia (10-70 min) and, apparently, were not dependent on the level of sensory block, which varied between T3 and T8. One patient was nauseated seconds before the asystole, otherwise there was no warning signs. All the patients were easily resuscitated with the prompt administration of atropine and ephedrine and, in the case of cardiac arrest, cardiac massage and ventilation with oxygen. One patient was treated with a small dose of adrenaline. Four patients had the surgery, as planned; one had the surgery postponed. All the patients were discharged from hospital in good health and did not suffer any sequelae.

Adult↗
PubMed2000

Chemical composition of individual aerosol particles in workplace air during production of manganese alloys.

Aerosol particle samples were collected at ELKEM ASA ferromanganese (FeMn) and silicomanganese (SiMn) smelters at Porsgrunn, Norway, during different production steps: raw material mixing, welding of protective steel casings, tapping of FeMn and slag, crane operation moving the ladles with molten metal, operation of the Metal Oxygen Refinement (MOR) reactor and casting of SiMn. Aerosol fractions were assessed for the analysis of the bulk elemental composition as well as for individual particle analysis. The bulk elemental composition was determined by inductively coupled plasma atomic emission spectrometry. For individual particle analysis, an electron microprobe was used in combination with wavelength-dispersive techniques. Most particles show a complex composition and cannot be attributed to a single phase. Therefore, the particles were divided into six groups according to their chemical composition: Group I, particles containing mainly metallic Fe and/or Mn; Group II, slag particles containing mainly Fe and/or Mn oxides; Group III, slag particles consisting predominantly of oxidized flux components such as Si, Al, Mg, Ca, Na and K; Group IV, particles consisting mainly of carbon; Group V, mixtures of particles from Groups II, III and IV; Group VI, mixtures of particles from Groups II and III. In raw material mixing, particles originating from the Mn ores were mostly found. In the welding of steel casings, most particles were assigned to Group II, Mn and Fe oxides. During the tapping of slag and metal, mostly slag particles from Group III were found (oxides of the flux components). During movement of the ladles, most particles came from Group II. At the MOR reactor, most of the particles belonged to the slag phase consisting of the flux components (Group III). The particles collected during the casting of SiMn were mainly attributed to the slag phase (Groups III and V). Due to the compositional complexity of the particles, toxicological investigations on the kinetics of pure compounds may not be easily associated with the results of this study.

Aerosols↗
PubMed2000

Chemical composition of individual aerosol particles from working areas in a nickel refinery.

Individual aerosol particles (n = 1170) collected at work stations in a nickel refinery were analyzed by wavelength-dispersive electron-probe microanalysis. By placing arbitrary restrictions on the contents of sulfur and silicon, the particles could be divided into four main groups. Scanning electron images indicated that most of the particles examined were relatively small (< or = 2 microm, equivalent projected area diameter), and that their morphology suggested formation from a melt. There was an absence of well-defined phases and simple stoichiometries, indicating that exposures to pure substances such as nickel subsulfide or specific oxides appeared not to occur. Although the elemental composition of particles varied greatly, a rough association was evident with the known elemental content of the refinery intermediates. The implications of the findings for aerosol speciation measurements, toxicological studies and interpretation of adverse health effects are explored.

Aerosols↗
PubMed1999

A comparison of train-of-four monitoring: mechanomyography at the thumb vs acceleromyography at the big toe.

BACKGROUND: It is not known if the information on neuromuscular function obtained from the hand is interchangeable with that of the foot. In the present study the agreement of thumb mechanomyography with acceleromyography of the big toe was studied. METHODS: Ten healthy patients scheduled for oral surgery were studied. Anaesthesia was induced with fentanyl 2 micrograms kg-1 and propofol 2 mg kg-1, and maintained with propofol 100-175 micrograms kg-1 min-1, nitrous oxide 60-70%, and fentanyl 1-2 micrograms kg-1 h-1. Vecuronium 0.1 mg kg-1 was used for muscle relaxation. Mechanomyography (MMG) of the thumb (Myograph 2000) and acceleromyography (AMG) of the big toe (TOF-Guard) were recorded simultaneously in all patients, and onset, period of no-twitch response, duration of action, and spontaneous recovery time obtained from both muscle groups. The agreement between methods was tested by calculation of bias and limits of agreement. RESULTS: The onset time and duration of action were significantly shorter (87 s vs 154 s, and 35 min vs 38 min, respectively), and the spontaneous recovery time significantly longer in the thumb than in the big toe (32 min vs 19 min). Period of no-twitch response was not significantly different in the two muscle groups. Limits of agreement (thumb big toe) were -21 to -113 s, -7 to 1 min, and -9 to 35 min, for onset time, duration of action, and spontaneous recovery time, respectively. CONCLUSIONS: We conclude that clinically acceptable agreement between thumb mechanomyography and big toe acceleromyography was found for the period of no-twitch response, suggesting that the timing of supplemental doses of vecuronium can be guided by AMG at the big toe. However, the spontaneous recovery time agreement (to TOF ratio = 0.75) between the thumb and the big toe was poor.

Acceleration↗
PubMed1999

Characterisation of workers' exposure in a Russian nickel refinery.

In support of a feasibility study of reproductive and developmental health among females employed in the Monchegorsk (Russia) nickel refinery, personal exposure and biological monitoring assessments were conducted. The inhalable aerosol fraction was measured and characterised by chemical speciation and particle-size distribution measurements. Unexpected findings were that: (i), pyrometallurgical working environments had significant levels of water-soluble nickel; (ii), significant exposure to cobalt occurred for the nickel workers; (iii), particles of size corresponding to the thoracic and respirable fractions appeared to be virtually absent in most of the areas surveyed. The water-soluble fraction is judged to be primarily responsible for the observed urinary nickel and cobalt concentrations. It is concluded relative to current international occupational-exposure limits for nickel in air, and because of the high nickel concentrations observed in urine, that the Monchegorsk nickel workers are heavily exposed. The implication of this finding for follow-up epidemiological work is alluded to.

Adult↗
PubMed1999

Correlation of urinary nickel excretion with observed 'total' and inhalable aerosol exposures of nickel refinery workers.

An investigation of the relationship between observed nickel aerosol exposures and urinary nickel excretion was undertaken at a Scandinavian nickel refinery. The goal of the study was to assess the impact of nickel aerosol speciation, the use of particle size-selective sampling instrumentation and adjustment of urinary levels for creatinine excretion on the usefulness of urinary nickel excretion as a marker for exposure. Urinary nickel measurements and paired 'total' and inhalable aerosol exposure measurements were collected each day for one week from refinery workers in four process areas. The mean observed urinary nickel concentration was 12 micrograms L-1 (11 micrograms of Ni per g of creatinine). The strongest relationships between urinary excretion and aerosol exposure were found when urinary nickel levels were adjusted for creatinine excretion and when exposure to only soluble forms of nickel aerosol was considered. No significant difference was observed between measures of 'total' and inhalable aerosol in the ability to predict urinary excretion patterns. In the light of these results, it is recommended that consideration be given to the chemical species distribution of nickel aerosol in the use of urinary nickel measurements as a screening tool for cancer risk in occupationally-exposed populations.

Adult↗
PubMed1998

[Intraspinal hematoma after thoracic epidural analgesia].

In one year three patients were operated on for spinal haematomas following thoracic epidural analgesia. All three patients experienced back pain and developed progressive paraparesis, one in connection with insertion of the catheter and two after its removal. A spinal block was visualized using MRI in two patients and myelography in one. The patients were operated on with posterior decompression. In two patients an epidural haematoma was evacuated. Both patients recovered neurologic function, one completely. The third patient, who had a subarachnoidal hemorrhage and an intramedullar haematoma, remained paralytic.

Adolescent↗
PubMed1997

Effect of combined endurance, strength and sprint training on maximal oxygen uptake, isometric strength and sprint performance in female elite handball players during a season.

Eight female handball players from the Norwegian national team were tested for maximal oxygen uptake, maximal isometric strength and maximal running velocity on four occasions during a year. The first test (T1) was made at the beginning of the preparation for a new season, the second (T2) in the middle of the preparation period, the third (T3) at the beginning of the season for the national league, and the fourth (T4) just before the most important tournament for the national team that year. Between T1 and T2 strength training had priority, between T2 and T3 endurance and sprint training had priority, and between T3 and T4 physical training was reduced. Mean maximal oxygen uptake was 51.3 +/- 2.3 ml x kg(-1) x min(-1) at T1 and was at the same level at T2. At T3 and T4 maximal oxygen uptake was increased to 53.8 +/- 2.7 and 53.5 +/- 2.9 ml x kg(-1) x min(-1) (p < 0.05), respectively. Mean maximal isometric strength increased from 154.6 +/- 25.7 at T1 to 168.9 +/- 26.8 N at T3 (p < 0.03). Mean maximal running velocity was 7.85 +/- 0.24 m x s(-1) at T1 and was not significantly changed at T2 and T3, but was increased to 8.02 +/- 0.22 m x s(-1) at T4 (p < 0.03). In conclusion with our training model, where strength training had priority in the first part of the training period, followed by a period where sprint and endurance training had priority, we were able to increase both maximal oxygen uptake and maximal running velocity in female elite handball players in the period with the most important tournament.

Adult↗
PubMed1997

Combined endovascular and surgical treatment in vertebral arteriovenous fistula. A case report.

A 7-year-old girl with a right-sided congenital arteriovenous fistula in the neck was admitted with signs of cardial incompensation. Her fistula was fed from the right vertebral artery in antegrade as well as retrograde directions. A steal from the intracranial arteries was established. In addition, smaller feeding arteries from the neck were found. She was operated on with ligation of the right vertebral artery proximal to the fistula but the attempted ligation of the artery cranially to the fistula was unsuccessful. She was therefore embolized by the formation of a plug of platinum fiber coils in the upper right vertebral artery. Catheterization was performed from the left vertebral artery via the basilar artery. Persisting minor feeders to the fistula from cervical arteries were embolized in a second session. Finally, surgical extirpation of the fistula was performed together with the operative ligation of a crossover feeding artery from the left vertebral artery. Her heart size, heart rate and blood pressure were successively normalized.

Arteriovenous Fistula↗
PubMed1995

A method for establishing tentative occupational exposure limits for inhalable dust.

Four-fold classification tables are used on five datasets containing 112 parallel personal measurements of total dust and inhalable dust. The classification are carried out in such a way that the frequency of non-compliance is equal for total dust and inhalable dust. The results can be used as tentative occupational exposure limits (OELs) for inhalable dust, and the results range from 0.7 to 3.4 of OELs for total dust. The results depend on the industry and the content of the dust.

Dust↗
PubMed1994

Erector spinae lever arm length variations with changes in spinal curvature.

Magnetic resonance imaging was used to study the effect of different curvatures in the lumbar spine on lever arm lengths of the erector spinae musculature. Eleven subjects were instructed to simulate static lifts while lying supine in a magnetic resonance camera with the lumbar spine either in kyphosis or lordosis. A sagittal image of the spine was obtained to analyze the lumbosacral angle and to guide the imaging of transverse sections through each disc (L1/L2 to L5/S1). Images were analyzed for lever arm lengths of the erector spinae muscle (ES) and the erector spinae aponeurosis (ESA), the latter functioning as a tendon for superiorly positioned ES muscle portions. The lumbosacral angle (between superior surfaces of S1 and L4) averaged 44 degrees in the lordosed, 26 degrees in the kyphosed and 41 degrees in a neutral supine position. In lordosis, the lever arm lengths were significantly longer than in kyphosis for all levels, averaging 60-63 mm (ES) and 82-86 mm (ESA). The corresponding values for kyphosis were 49-57 mm (ES) and 67-77 mm (ESA), respectively. Thus, there was a considerable effect (10-24%) of lumbar curvature on lever arm lengths for the back extensor muscles. The change in leverage will affect the need for extensor muscle force and thus the magnitude of compression in the lumbar spine in loading situations such as lifting.

Adult↗