[The effect of industrial factors on health of crew members of bulk-oil fleet].

The negative effect of oil vapors and oil products on health of crew of tanker fleet is a large-scale problem of shipping since safety of life and health of seamen is declared as essential value in implementation of production activity. The inert gases emitted during handling and transportation of oil products, in view of their toxicity, may result not only in acute intoxication but also in development of chronic diseases when inhaling harmful substances in moderate concentrations. The article considers main professional industrial factors that affect crew members of bulk-oil fleet, symptomatology of intoxication and initial care of crew members, application of personal cover when working with this type of cargo. The special attention is paid to chronic diseases developing against the background of negative effect of oil products on health of seamen. The recommendations of prevention and timely detection of their development are proposed.

Alternatives to Carbon Dioxide in Two Phases for the Improvement of Broiler Chickens' Welfare during Stunning.

This study evaluated the exposure to gas mixtures of carbon dioxide (CO2) associated with nitrogen (N2) as alternatives to CO2 in two phases to improve the welfare of broiler chickens at slaughter. Broilers were exposed to one of three treatments: 40C90C (1st phase: <40% CO2 for 2 min; 2nd phase: >90% CO2 and <2% O2 for 2 min, n = 92), 40C60N (40% CO2, 60% N2, and <2% O2 for 4 min, n = 79), or 20C80N (20% CO2, 80% N2, and <2% O2 for 4 min, n = 72). Brain activity (EEG) was assessed to determine the onset of loss of consciousness (LOC) and death. Behavioural assessment allowed for characterisation of an aversive response to the treatments and confirmed loss of posture (LOP) and motionlessness as behavioural proxies of LOC and brain death in 40C60N and 20N80C. However, the lack of quality of the EEG traces obtained in 40C90C did not allow us to determine the onset of LOC and brain death for this treatment. The onset of LOC in 40C60N was found at 19 s [14-30 s] and in 20C80N at 21 s [16-37 s], whereas a LOP was seen at 53 s [26-156 s] in 40C90C. Birds showed brain death in 40C60N at 64 s [43-108 s] and in 20C80N at 70 s [45-88 s]), while they became motionless in 40C90C at 177 s [89-212 s]. The 40C90C birds not only experienced more events of aversive behaviours related to mucosal irritation, dyspnoea, and breathlessness during induction to unconsciousness but were at risk of remaining conscious when the CO2 concentration was increased in the 2nd phase (known to cause severe pain). From an animal welfare point of view, 40C60N proved to be the least aversive of the three treatments tested, followed by 20C80N and 40C90C.

A modified and rapid method for the single-well push-pull (SWPP) test using SF6, Kr, and uranine tracers.

In the present study, a single-well push-pull (SWPP) test was conducted with multi-component tracers, including inert gas (SF6 and Kr) and uranine (conservative), to understand the volatile/semi-volatile component transport characteristics in the groundwater system. In an SWPP test, it is essential to obtain an initial breakthrough curve (BTC) of the inert gas concentration at the beginning of the pulling stage to analyze the hydraulic properties of the groundwater system. As a result of the SWPP test using a proposed method in this study, physicochemical parameters of the groundwater and BTC of gas tracers and uranine were acquired simultaneously and successfully. In addition, on-site measurements of uranine, pCO2, and water quality data, such as electrical conductivity (EC), temperature, pH, and dissolved oxygen, were undertaken. Modification of an existing pCO2 measuring system allowed the gas samples to be collected, transported, and analyzed for inert gas components within a few hours. As a result, reliable and interpretable data with a recovery ratio of 26%, 85%, and 95% for SF6, Kr, and uranine, respectively, were obtained. The differences in the recovery ratio were utilized to identify the environmental system, whether it contains gas inside the isolated system (closed) or not (open), and to understand plume behavior characteristics in the experimental zone. By applying a two-dimensional advection-dispersion model to the acquired tracer test data and comparing the observed and computed tracer concentrations, helpful information was obtained on the hydraulic and transport characteristics of the targeted zone. This method can be extended to the design of dissolved CO2 transport monitoring of an aquifer above a CCS site.

Spectroscopy of Laser-Induced Dielectric Breakdown Plasma in Mixtures of Air with Inert Gases Ar, He, Kr, and Xe.

The generation of ozone and nitrogen oxides by laser-induced dielectric breakdown (LIDB) in mixtures of air with noble gases Ar, He, Kr, and Xe is investigated using OES and IR spectroscopy, mass spectrometry, and absorption spectrophotometry. It is shown that the formation of NO and NO2 noticeably depends on the type of inert gas; the more complex electronic configuration and the lower ionization potential of the inert gas led to increased production of NO and NO2. The formation of ozone occurs mainly due to the photolytic reaction outside the gas discharge zone. Equilibrium thermodynamic analysis showed that the formation of NO in mixtures of air with inert gases does not depend on the choice of an inert gas, while the equilibrium concentration of the NO+ ion decreases with increasing complexity of the electronic configuration of an inert gas.

Effect of Different Gas-Stunning Conditions on Heme Pigment Solutions and on the Color of Blood, Meat, and Small Intestine of Rabbits.

The objectives of this study were to elucidate the effect of different high-concentration levels of inert gases (Ar and N2) on heme-pigment solutions and on the color of the blood, meat, and small intestine of rabbits; and to figure out the proper concentration level of inert gas (Ar or N2) for the complete stunning of the rabbit. To observe the changing of color attributes, a research study was conducted in the abattoir of the National Institute of Animal Science (NIAS), RDA, Republic of Korea. This experiment had 2 parts, (i) A trial on heme-pigment solutions (hemoglobin and myoglobin solution) was conducted in a gas chamber with different high-concentration levels of carbon dioxide, argon, nitrogen, and normal air; and (ii) a rabbit experiment was conducted­stunning with different high-concentration levels of carbon dioxide, argon, nitrogen, and the Halal method (non-stunning). A small-size digital gas chamber was used for this experiment (size: width 850 mm × depth 1350 mm). Artificial hemoglobin (Hb) and myoglobin (Mb) solutions were created from "porcine hemoglobin lyophilized powder" and "equine skeletal muscle myoglobin lyophilized powder", respectively. In the heme-pigment solutions trial, 10 treatments were used: (i) 80% carbon dioxide (T1), (ii) 85% carbon dioxide (T2), (iii) 90% carbon dioxide (T3), (iv) 80% argon (T4), (v) 85% argon (T5), (vi) 90% argon (T6), (vii) 80% nitogen (T7), (viii) 85% nitogen (T8), (ix) 90% nitogen (T9), and (x) normal air (T10). Heme-pigment solutions (both Hb and Mb) were exposed with each treatment for four separate durations of time (30 s, 1 min, 2 min, and 4 min); and every sample (Hb and Mb) was exposed during each duration of time for 10 times (n = 10). In the rabbit experiment, seven treatments were used (i) 85% carbon dioxide (T1), (ii) 90% carbon dioxide (T2), (iii) 85% argon (T3), (iv) 90% argon (T4), (v) 96% nitrogen (T5), (vi) 98% nitogen (T6), and (vii) the Halal method (non-stunning) (T7). Forty-two rabbits (mixed-breed) were collected from the nearest commercial farm and randomly selected for a treatment group (n = 6). The average body weight was 2.3 kg. For stunning, each individual rabbit was separately kept in a gas chamber, after which each specific gas was used to fulfill the desired level in the pit. After reaching the desired level of concentration, rabbits were stunned within a very short time. It was observed that the time required for stunning in the T1, T2, T3, T4, T5 and T6 treatment was 79−82, 68−73, 97−103, 88−91, 164−173, and 108−115 s, respectively. In the case of the Halal method (non-stunning), as per the rules of Islam, rabbits were slaughtered without stunning. After slaughtering, in all treatments, the blood, meat, and small intestine of each animal were collected carefully and kept in a cool room in which the temperature was −2 °C, and after 24 h, the color attributes­lightness (L*), redness (a*), and yellowness (b*)­were measured via a Chroma Meter. It was found that in both experiments (trial on heme-pigment solutions and rabbit stunning), the color values (L*, a* and b*) showed a significant difference (p < 0.05) among the treatment groups. The CO2-treated groups showed high redness (a*) and low lightness (L*) and yellowness (b*), which indicated a dark-red color, and N2-treated groups showed high lightness (L*) and yellowness (b*) and low redness (a*), which implied a bright-red color. The effect of the Ar was in between the CO2- and N2-treated groups. These phenomena were observed both in the heme-pigment solutions (Hb and Mb) and in the blood, meat, and small intestine of the rabbits. N2-stunned animals fulfill the fundamental desire of consumers to purchase bright red-colored fresh meat. Therefore, in view of color attributes, consumer satisfaction, and animal welfare, N2 gas can be thought of as a valuable alternative to stunning. Considering the time required for complete stunning and desirable color attributes, a 98% concentration of N2 is best for rabbit stunning. As such, it could be used as a better option for the gas stunning of animals.

[Results of the application of complex physiotherapeutic neurostimulation in optical neuropathies of various genesis]. / Rezul'taty primeneniya kompleksnoi fizioterapevticheskoi neirostimulyatsii pri opticheskikh neiropatiyakh sosudistogo geneza.

Optical neuropathies (ON) are the outcome of many diseases of various origins. The main ones are classified as inflammatory, vascular and traumatic ON. ON lead to subatrophy of the optic nerve, but even after the completion of treatment, it is possible to improve visual functions by using physiotherapeutic means of ophthalmic rehabilitation. OBJECTIVE: To evaluate the effectiveness of complex physiotherapeutic neuro-ophthalmostimulation in case of ON of vascular origin. MATERIAL AND METHODS: The study included 60 patients (120 eyes) with a verified diagnosis of optic neuropathy of vascular origin, who were divided into 2 groups comparable in age, gender and anatomical and functional characteristics: the main group of 30 patients (60 eyes) and the control group - 30 patients (60 eyes), including 24 men and 36 women, mean age was 66.2±4.1 years, disease duration was 4.1±1.7 years. All patients underwent courses of conservative treatment with vitamins according to the available ophthalmological standards, repeating them 1-2 times a year, the last of which was six months before the present study. Physiotherapy courses and patients did not pass. 20 healthy volunteers were taken to create basic indicators of the «norm¼ of the applied research methods. Patients of the main group used a set of procedures: transcranial magnetic electrical stimulation, endonasal electrophoresis with the drug neuroprotector Semax 0.1%, oxybaric chamber and acupuncture. Patients in the control group were prescribed basic therapy, including taking the vitamin complex BEROCCA for 3 months. Breakpoints: before treatment and at times: 1st week, 12 weeks and 24 weeks after the course of treatment, according to the standard recommendations for international multicenter studies. The following were assessed: visual field boundaries (dilation meridians; in deg.), light sensitivity (MS, MD; in dB), indicators of the state of the retinal ganglion layer (GCS thickness, volume loss): Avg CCG (in µm), FLV, GLV (in %). RESULTS: When evaluating the results in patients of the main group who received complex neurostimulation, the therapeutic efficacy in a week after the end of treatment was 94%, in 12 weeks - in 88% and in 24 weeks - 83%, while in patients of the control group for all studied indicators showed only a positive trend and therapeutic efficacy did not exceed 30-42%. CONCLUSION: Under the influence of the developed neurostimulating complex, the activity of nerve cells objectively increases, leading to a significant increase in the boundaries of the field of view and light sensitivity and a decrease in global losses of the retinal ganglion complex and optic nerve.

Neuroprotection by the noble gases argon and xenon as treatments for acquired brain injury: a preclinical systematic review and meta-analysis.

BACKGROUND: The noble gases argon and xenon are potential novel neuroprotective treatments for acquired brain injuries. Xenon has already undergone early-stage clinical trials in the treatment of ischaemic brain injuries, with mixed results. Argon has yet to progress to clinical trials as a treatment for brain injury. Here, we aim to synthesise the results of preclinical studies evaluating argon and xenon as neuroprotective therapies for brain injuries. METHODS: After a systematic review of the MEDLINE and Embase databases, we carried out a pairwise and stratified meta-analysis. Heterogeneity was examined by subgroup analysis, funnel plot asymmetry, and Egger's regression. RESULTS: A total of 32 studies were identified, 14 for argon and 18 for xenon, involving measurements from 1384 animals, including murine, rat, and porcine models. Brain injury models included ischaemic brain injury after cardiac arrest (CA), neurological injury after cardiopulmonary bypass (CPB), traumatic brain injury (TBI), and ischaemic stroke. Both argon and xenon had significant (P<0.001), positive neuroprotective effect sizes. The overall effect size for argon (CA, TBI, stroke) was 18.1% (95% confidence interval [CI], 8.1-28.1%), and for xenon (CA, TBI, stroke) was 34.1% (95% CI, 24.7-43.6%). Including the CPB model, only present for xenon, the xenon effect size (CPB, CA, TBI, stroke) was 27.4% (95% CI, 11.5-43.3%). Xenon, both with and without the CPB model, was significantly (P<0.001) more protective than argon. CONCLUSIONS: These findings provide evidence to support the use of xenon and argon as neuroprotective treatments for acquired brain injuries. Current evidence suggests that xenon is more efficacious than argon overall.

Timely and Appropriate Administration of Inhaled Argon Provides Better Outcomes for tMCAO Mice: A Controlled, Randomized, and Double-Blind Animal Study.

BACKGROUND: Inhaled argon (iAr) has shown promising therapeutic efficacy for acute ischemic stroke and has exhibited impressive advantages over other inert gases as a neuroprotective agent. However, the optimal dose, duration, and time point of iAr for acute ischemic stroke are unknown. Here, we explored variable iAr schedules and evaluated the neuroprotective effects of acute iAr administration on lesion volume, brain edema, and neurological function in a mouse model of cerebral ischemic/reperfusion injury. METHODS: Adult ICR (Institute of Cancer Research) mice were randomly subjected to sham, moderate (1.5 h), or severe (3 h) transient middle cerebral artery occlusion (tMCAO). One hour after tMCAO, the mice were randomized to variable iAr protocols or air. General and focal deficit scores were assessed during double-blind treatment. Infarct volume, overall recovery, and brain edema were analyzed 24 h after cerebral ischemic/reperfusion injury. RESULTS: Compared with those in the tMCAO-only group, lesion volume (p < 0.0001) and neurologic outcome (general, p < 0.0001; focal, p < 0.0001) were significantly improved in the group administered iAr 1 h after stroke onset (during ischemia). Short-term argon treatment (1 or 3 h) significantly improved the infarct volume (1 vs. 24 h, p < 0.0001; 3 vs. 24 h, p < 0.0001) compared with argon inhalation for 24 h. The concentration of iAr was confirmed to be a key factor in improving focal neurological outcomes relative to that in the tMCAO group, with higher concentrations of iAr showing better effects. Additionally, even though ischemia research has shown an increase in cerebral damage proportional to the ischemia time, argon administration showed significant neuroprotective effects on infarct volume (p < 0.0001), neurological deficits (general, p < 0.0001; focal, p < 0.0001), weight recovery (p < 0.0001), and edema (p < 0.0001) in general, particularly in moderate stroke. CONCLUSIONS: Timely iAr administration during ischemia showed optimal neurological outcomes and minimal infarct volumes. Moreover, an appropriate duration of argon administration was important for better neuroprotective efficacy. These findings may provide vital guidance for using argon as a neuroprotective agent and moving to clinical trials in acute ischemic stroke.

Neuroprotective Effects of the Inert Gas Argon on Experimental Traumatic Brain Injury In Vivo with the Controlled Cortical Impact Model in Mice.

Argon has shown neuroprotective effects after traumatic brain injury (TBI) and cerebral ischemia in vitro and in focal cerebral ischemia in vivo. The purpose of this study is to show whether argon beneficially impacts brain contusion volume (BCV) as the primary outcome parameter, as well as secondary outcome parameters, such as brain edema, intracranial pressure (ICP), neurological outcome, and cerebral blood flow (CBF) in an in-vivo model. Subjects were randomly assigned to either argon treatment or room air. After applying controlled cortical impact (CCI) onto the dura with 8 m/s (displacement 1 mm, impact duration 150 ms), treatment was administered by a recovery chamber with 25%, 50%, or 75% argon and the rest being oxygen for 4 h after trauma. Two control groups received room air for 15 min and 24 h, respectively. Neurological testing and ICP measurements were performed 24 h after trauma, and brains were removed to measure secondary brain damage. The primary outcome parameter, BCV, and the secondary outcome parameter, brain edema, were not significantly reduced by argon treatment at any concentration. There was a highly significant decrease in ICP at 50% argon (p = 0.001), and significant neurological improvement (beamwalk missteps) at 25% and 50% argon (p = 0.01; p = 0.049 respectively) compared to control.

Characterization and Control of Hidden Micro-Oxygenation in the Winery: Wine Racking.

Transferring wine is a common operation in most of the wineries in the world that depends mainly on the equipment and materials used. These contributions are widely unknown, and their knowledge is of vital importance to controlling the winemaking process. This work presents the results of characterizing the oxygen supply due to the use of hoses of different materials (Butyl Rubber, IIR; Nitrile Butadiene Rubber, NBR; Ethylene Propylene Diene Monomer rubber, EPDM; Ultra-high-molecular-weight polyethylene, UHMW; Natural Rubber, NR), dimensions (DN32; DN50), connectors (DIN 11851, Tri-CLAMP) with gaskets of different materials (NBR; EPDM; Fluorocarbon, FKM/FPM; silicone rubber, Q/VMQ; Polytetrafluoroethylene, PTFE). In addition, the use of different inert gases (N2, CO2, Ar, N2 + CO2 and Ar + CO2) for air purging of hoses and tanks, as well as for ullage blanketing during tank-to-tank racking, and their economic impact were studied. The results indicated that the IIR hoses had the least amount of O2 added to the liquid and that the Tri-clamp connectors were generally more airtight, with the FKM seals standing out. The most recommended inert gas was CO2 when the type of wine allows it, N2 being the most recommended in any case. When all these recommendations were used together the addition of O2 during tank-to-tank racking was drastically reduced.

[Suicidal helium inhalation - case report]. / Samobójstwo przy uzyciu helu ­ opis przypadku.

A significant increase in the number of suicides with the use of helium has been observed in recent years. Deaths with its use are quick and are not accompanied by a feeling of breathlessness. This paper presents the results of a post-mortem examination of a woman who committed suicide by inhaling helium. Conventional postmortem examination did not reveal any post-traumatic changes, while a computed tomography (CT) scans showed the presence of a large amount of gas in the veins and arteries of the whole body and in the heart chambers. In the assessment of postmortem computed tomography (PMCT) images, changes resulting from putrefaction were also taken into account. The results of the diagnostics carried out confirm the results of previous reports, which indicated that inhalation of large amounts of helium leads to death not only (as previously thought) in the oxygen displacement mechanism, but also through the formation of gas embolisms.

Is xenon a suitable euthanasia agent for mice?

OBJECTIVE: To compare behavioural and electrophysiological variables of mice undergoing gas euthanasia with either xenon (Xe) or carbon dioxide (CO2). STUDY DESIGN: Single animals chronically instrumented for electroencephalography (EEG) recording were randomized to undergo euthanasia with either CO2 or Xe (n = 6 animals per group). ANIMALS: Twelve adult (>6 weeks old) male C57Bl6/n mice. METHODS: Mice were surgically instrumented with EEG and electromyogram electrodes. Following a 7-day recovery period, animals were placed individually in a sealed chamber and a 5-minute baseline recorded in 21% O2. Gas [100% Xe (n = 6) or 100% CO2 (n = 6)] was then added to the chamber at 30% chamber volume minute-1 (2.8 L minute-1) until cessation of breathing. EEG, behaviour (jumping and freezing) and locomotion speed were recorded throughout. RESULTS: Mice undergoing single gas euthanasia with Xe did not show jumping or freezing behaviours and had reduced locomotion speed compared to baseline, in contrast to CO2, which resulted in increases in these variables. EEG recordings revealed sedative effects from Xe but heightened arousal from CO2. CONCLUSIONS: Our data suggest that Xe may be less aversive than CO2 when using a 30% chamber volume minute-1 fill rate and could improve the welfare of mice undergoing gas euthanasia.

Recent advances in the neuroprotective effects of medical gases.

Central nervous system injuries are a leading cause of death and disability worldwide. Although the exact pathophysiological mechanisms of various brain injuries vary, central nervous system injuries often result in an inflammatory response, and subsequently lead to brain damage. This suggests that neuroprotection may be necessany in the treatment of multiple disease models. The use of medical gases as neuroprotective agents has gained great attention in the medical field. Medical gases include common gases, such as oxygen, hydrogen and carbon dioxide; hydrogen sulphide and nitric oxide that have been considered toxic; volatile anesthetic gases, such as isoflurane and sevoflurane; and inert gases like helium, argon, and xenon. The neuroprotection from these medical gases has been investigated in experimental animal models of various types of brain injuries, such as traumatic brain injury, stroke, subarachnoid hemorrhage, cerebral ischemic/reperfusion injury, and neurodegenerative diseases. Nevertheless, the transition into the clinical practice is still lagging. This delay could be attributed to the contradictory paradigms and the conflicting results that have been obtained from experimental models, as well as the presence of inconsistent reports regarding their safety. In this review, we summarize the potential mechanisms underlying the neuroprotective effects of medical gases and discuss possible candidates that could improve the outcomes of brain injury.

A method for calculating the gas volume proportions and inhalation temperature of inert gas mixtures allowing reaching normothermic or hypothermic target body temperature in the awake rat.

The noble gases xenon (Xe) and helium (He) are known to possess neuroprotective properties. Xe is considered the golden standard neuroprotective gas. However, Xe has a higher molecular weight and lower thermal conductivity and specific heat than those of nitrogen, the main diluent of oxygen (O2) in air, conditions that could impair or at least reduce the intrinsic neuroprotective properties of Xe by increasing the critical care patient's respiratory workload and body temperature. In contrast, He has a lower molecular weight and higher thermal conductivity and specific heat than those of nitrogen, but is unfortunately far less potent than Xe at providing neuroprotection. Therefore, combining Xe with He could allow obtaining, depending on the gas inhalation temperature and composition, gas mixtures with neutral or hypothermic properties, the latter being advantageous in term of neuroprotection. However, calculating the thermal properties of a mixture, whatever the substances - gases, metals, rubbers, etc. - is not trivial. To answer this question, we provide a graphical method to assess the volume proportions of Xe, He and O2 that a gas mixture should contain, and the inhalation temperature to which it should be administered to allow a clinician to maintain the patient at a target body temperature.

Xenon-helium gas mixture at equimolar concentration of 37.5% protects against oxygen and glucose deprivation-induced injury and inhibits tissue plasminogen activator.

Xenon (Xe) is considered to be the golden standard neuroprotective gas. However, Xe has a higher molecular weight and lower thermal conductivity and specific heat than those of nitrogen, the main diluent of oxygen in air. These physical characteristics could impair or at least reduce the intrinsic neuroprotective action of Xe by increasing the patient's respiratory workload and body temperature. In contrast, helium (He) is a cost-efficient gas with a lower molecular weight and higher thermal conductivity and specific heat than those of nitrogen, but is far less potent than Xe. In this study, we hypothesized that mixing Xe and He could allow obtaining a neuroprotective gas mixture with advantageously reduced molecular weight and increased thermal conductivity. We found that Xe and He at the equimolar concentration of 37.5% reduced oxygen-glucose deprivation-induced increase in lactate dehydrogenase in brain slices, an ex vivo model of acute ischemic stroke. These results together with the effects of Xe-He on the thrombolytic efficiency of tissue plasminogen activator are discussed.

Ventilatory response to nitrogen multiple-breath washout in infants.

BACKGROUND: Nitrogen multiple-breath washout (N2 MBW) using 100% oxygen (O2) has regained interest to assess efficiency of tracer gas clearance in, for example, children with Cystic Fibrosis (CF). However, the influence of hyperoxia on the infants' respiratory control is unclear. We assessed safety and impact on breathing pattern from hyperoxia, and if exposure to 40% O2 first induces tolerance to subsequent 100% O2 for N2 MBW. METHODS: We prospectively enrolled 39 infants aged 3-57 weeks: 15 infants with CF (8 sedated for testing) and 24 healthy controls. Infants were consecutively allocated to the protocols comprising of 100% O2 or 40/100% O2 administered for 30 breaths. Lung function was measured using an ultrasonic flowmeter setup. Primary outcome was tidal volume (VT). RESULTS: None of the infants experienced apnea, desaturation, or bradycardia. Both protocols initially induced hypoventilation. VT temporarily declined in 33/39 infants across 10-25 breaths. Hypoventilation occurred independent of age, disease, and sedation. In the new 40/100% O2 protocol, VT returned to baseline during 40% O2 and remained stable during 100% O2 exposure. End-tidal carbon dioxide monitored online did not change. CONCLUSION: The classical N2 MBW protocol with 100% O2 may change breathing patterns of the infants. The new protocol with 40% O2 induces hyperoxia-tolerance and does not lead to changes in breathing patterns during later N2 washout using 100% O2. Both protocols are safe, the new protocol seems an attractive option for N2 MBW in infants.

[Hyperbaric oxygen therapy and inert gases in cerebral ischemia and traumatic brain injury]. / Oxygénothérapie hyperbare et gaz inertes dans l'ischémie cérébrale et le traumatisme crânien.

Cerebral ischemia is a common thread of acute cerebral lesions, whether vascular or traumatic origin. Hyperbaric oxygen (HBO) improves tissue oxygenation and may prevent impairment of reversible lesions. In experimental models of cerebral ischemia or traumatic brain injury, HBO has neuroprotective effects which are related to various mechanisms such as modulation of oxidative stress, neuro-inflammation or cerebral and mitochondrial metabolism. However, results of clinical trials failed to prove any neuroprotective effects for cerebral ischemia and remained to be confirmed for traumatic brain injury despite preliminary encouraging results. The addition of inert gases to HBO sessions, especially argon or xenon which show neuroprotective experimental effects, may provide an additional improvement of cerebral lesions. Further multicentric studies with a strict methodology and a better targeted definition are required before drawing definitive conclusions about the efficiency of combined therapy with HBO and inert gases in acute cerebral lesions.

Multiple inert gas elimination technique by micropore membrane inlet mass spectrometry--a comparison with reference gas chromatography.

The mismatching of alveolar ventilation and perfusion (VA/Q) is the major determinant of impaired gas exchange. The gold standard for measuring VA/Q distributions is based on measurements of the elimination and retention of infused inert gases. Conventional multiple inert gas elimination technique (MIGET) uses gas chromatography (GC) to measure the inert gas partial pressures, which requires tonometry of blood samples with a gas that can then be injected into the chromatograph. The method is laborious and requires meticulous care. A new technique based on micropore membrane inlet mass spectrometry (MMIMS) facilitates the handling of blood and gas samples and provides nearly real-time analysis. In this study we compared MIGET by GC and MMIMS in 10 piglets: 1) 3 with healthy lungs; 2) 4 with oleic acid injury; and 3) 3 with isolated left lower lobe ventilation. The different protocols ensured a large range of normal and abnormal VA/Q distributions. Eight inert gases (SF6, krypton, ethane, cyclopropane, desflurane, enflurane, diethyl ether, and acetone) were infused; six of these gases were measured with MMIMS, and six were measured with GC. We found close agreement of retention and excretion of the gases and the constructed VA/Q distributions between GC and MMIMS, and predicted PaO2 from both methods compared well with measured PaO2. VA/Q by GC produced more widely dispersed modes than MMIMS, explained in part by differences in the algorithms used to calculate VA/Q distributions. In conclusion, MMIMS enables faster measurement of VA/Q, is less demanding than GC, and produces comparable results.

Multiproperty empirical isotropic interatomic potentials for CH4-inert gas mixtures.

An approximate empirical isotropic interatomic potentials for CH4-inert gas mixtures are developed by simultaneously fitting the Exponential-Spline-Morse-Spline-van der Waals (ESMSV) potential form to viscosity, thermal conductivity, thermal diffusion factors, diffusion coefficient, interaction second pressure virial coefficient and scattering cross-section data. Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures for CH4-He and at T = 87 K for CH4-Ar are computed using theoretical values for overlap, octopole and hexadecapole mechanisms and interaction potential as input. Also, the quantum mechanical lineshapes of collision-induced light scattering (CILS) for the mixtures CH4-Ar and CH4-Xe at room temperature are calculated. The spectra of scattering consist essentially of an intense, purely translational component which includes scattering due to free pairs and bound dimers, and the other is due to the induced rotational scattering. These spectra have been interpreted by means of pair-polarizability terms, which arise from a long-range dipole-induced-dipole (DID) with small dispersion corrections and a short-range interaction mechanism involving higher-order dipole-quadrupole A and dipole-octopole E multipole polarizabilities. Good agreement between computed and experimental lineshapes of both absorption and scattering is obtained when the models of potential, interaction-induced dipole and polarizability components are used.