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T Marx

Publications and source records attributed to T Marx.

At least 37 records · Page 2Linked to original sources
PubMed1999

Parturition at term: parallel increases in interleukin-8 and proteinase concentrations and neutrophil count in the lower uterine segment.

A relationship was sought between the tissue concentrations of interleukin (IL)-8, matrix metalloproteinase (MMP)-8 and MMP-9, and the numbers of the various leukocytes infiltrating the lower uterine segment stroma during parturition. Biopsy specimens of the lower uterine segment were obtained from 63 women undergoing Caesarean section at various stages of cervical dilatation at term. The concentrations of IL-8, MMP-8 and MMP-9 were determined with enzyme-linked immunosorbent assays, and the leukocytes were quantified immunohistochemically. The median IL-8 concentration (pg/mg total protein) rose significantly from 17.2 at < 2 cm dilatation, to 26.5 at 2 to < 4 cm dilatation, and 1954.0 at 4-6 cm dilatation, and remained at approximately this concentration at > 6 cm dilatation. The median MMP-8 concentration (ng/mg total protein) increased significantly from 32.2 at < 2 cm dilatation to 114.2 at > 6 cm dilatation. The median MMP-9 concentration (ng/mg total protein) rose significantly from 15.4 at < 2 cm dilatation to 102.1 at > 6 cm dilatation. The number of neutrophils was significantly higher at 4-6 cm and > 6 cm dilatation than at > 2 cm, reaching maximum values at > 6 cm dilatation. The findings in this study support the hypothesis that IL-8-induced infiltration of the cervical stroma by neutrophils and subsequent release of proteinases may play a key role in parturition.

Adult↗
PubMed1999

Continuous arterial P(O2) and P(CO2) measurements in swine during nitrous oxide and xenon elimination: prevention of diffusion hypoxia.

BACKGROUND: During nitrous oxide (N2O) elimination, arterial oxygen tension (PaO2) decreases because of the phenomenon commonly called diffusive hypoxia. The authors questioned whether similar effects occur during xenon elimination. METHODS: Nineteen anesthetized and paralyzed pigs were mechanically ventilated randomly for 30 min using inspiratory gas mixtures of 30% oxygen and either 70% N2O or xenon. The inspiratory gas was replaced by a mixture of 70% nitrogen and 30% oxygen. PaO2 and carbon dioxide tensions were recorded continuously using an indwelling arterial sensor. RESULTS: The PaO2 decreased from 119+/-10 mm Hg to 102+/-12 mm Hg (mean+/-SD) during N2O washout (P<0.01) and from 116+/-9 mm Hg to 110+/-8 mm Hg during xenon elimination (P<0.01), with a significant difference (P<0.01) between baseline and minimum PaO2 values (deltaPaO2, 17+/-6 mm Hg during N2O washout and 6+/-3 mm Hg during xenon washout). The PaCO2 value also decreased (from 39.3+/-6.3 mm Hg to 37.6+/-5.8 mm Hg) during N2O washout (P<0.01) and during xenon elimination (from 35.4+/-1.6 mm Hg to 34.9+/-1.6 mm Hg; P< 0.01). The deltaPaCO2 was 1.7+/-0.9 mm Hg in the N2O group and 0.5+/-0.3 mm Hg in the xenon group (P<0.01). CONCLUSION: Diffusive hypoxia is unlikely to occur during recovery from xenon anesthesia, probably because of the low blood solubility of this gas.

Anesthetics, Inhalation↗
PubMed1999

Xenon does not trigger malignant hyperthermia in susceptible swine.

BACKGROUND: Xenon is a noble gas with anesthetic properties currently under investigation for use in humans. This study was performed to evaluate whether xenon may trigger malignant hyperthermia in susceptible swine. METHODS: Nine malignant hyperthermia-sensitive swine (Pietrain) were initially anesthetized with pentobarbital and then ventilated with 70% xenon in oxygen for 2 h. Heart rate, mean arterial pressure, cardiac output, body temperature, arterial and mixed-venous blood gases, and plasma catecholamine and lactate levels were measured every 10 min both during xenon-oxygen ventilation and after a 30-min xenon washout phase followed by subsequent administration of halothane (1% inspired) and succinylcholine (3 mg/kg intravenous). During the investigation, no malignant hyperthermia-specific therapy was instituted. RESULTS: Xenon exposure did not induce any changes in metabolic and hemodynamic parameters nor elevations of the plasma catecholamine levels indicative for an episode of malignant hyperthermia. By contrast, in all animals, within 20 min after the administration of halothane and succinylcholine, fulminant and fatal malignant hyperthermia episodes were initiated. CONCLUSIONS: The authors conclude that xenon does not trigger malignant hyperthermia in susceptible swine.

Amino Acid Substitution↗
PubMed1999

Respiratory mechanics during xenon anesthesia in pigs: comparison with nitrous oxide.

BACKGROUND: Because of its high density and viscosity, xenon (Xe) may influence respiratory mechanics when used as an inhaled anesthetic. Therefore the authors studied respiratory mechanics during xenon and nitrous oxide (N2O) anesthesia before and during methacholine-induced bronchoconstriction. METHODS: Sixteen pentobarbital-anesthetized pigs initially were ventilated with 70% nitrogen-oxygen. Then they were randomly assigned to a test period of ventilation with either 70% xenon-oxygen or 70% N2O-oxygen (n = 8 for each group). Nitrogen-oxygen ventilation was then resumed. Tidal volume and inspiratory flow rate were set equally throughout the study. During each condition the authors measured peak and mean airway pressure (Pmax and Pmean) and airway resistance (R(aw)) by the end-inspiratory occlusion technique. This sequence was then repeated during a methacholine infusion. RESULTS: Both before and during methacholine airway resistance was significantly higher with xenon-oxygen (4.0 +/- 1.7 and 10.9 +/- 3.8 cm H2O x s(-1) x 1(-1), mean +/- SD) when compared to nitrogen-oxygen (2.6 +/- 1.1 and 5.8 +/- 1.4 cm H2O x s(-1) x l(-1), P < 0.01) and N2O-oxygen (2.9 +/- 0.8 and 7.0 +/- 1.9, P < 0.01). Pmax and Pmean did not differ before bronchoconstriction, regardless of the inspired gas mixture. During bronchoconstriction Pmax and Pmean both were significantly higher with xenon-oxygen (Pmax, 33.1 +/- 5.5 and Pmean, 11.9 +/- 1.6 cm H2O) when compared to N2O-oxygen (28.4 +/- 5.7 and 9.5 +/- 1.6 cm H2O, P < 0.01) and nitrogen-oxygen (28.0 +/- 4.4 and 10.6 +/- 1.3 cm H2O, P < 0.01). CONCLUSIONS: Airway pressure and resistance are increased during xenon anesthesia. This response is moderate and not likely to assume major importance for the general use of xenon in anesthesia.

Algorithms↗
PubMed1998

A novel apparatus for the exposure of cultured cells to volatile agents.

This article presents a novel exposure apparatus that allows the exposure of cultured cells to volatile chemicals, e.g., inhalation anesthetics. The apparatus consists of an exposure chamber and a tightly linked vaporizer unit with pumps and valves allowing adjustable fluxes of mixtures of test chemicals and carrier gas under open and closed-circuit conditions. The exposure chamber uses commercially available cell culture flasks and accommodates up to 12 flasks simultaneously. Both modules fit into a standard culture incubator. The exposure chamber may be mounted onto an oscillating axis to tilt the cultures periodically forth and back, thus allowing direct contact of the cells with test atmosphere. The vaporizer unit is connected to a personal computer which lets the experimenter set the "open" and "close" intervals of individual valves thereby controlling the composition and flow rate of the test gas mixture. The vapor concentration of test chemicals can be monitored at the inlet and outlet using infrared photodetectors or mass spectrometers. Computer-aided processing of exposure protocols allows unattended runs. Exposure protocols can be scripted and stored on disk, thus ensuring interexperimental reproducibility of complex exposure profiles. As an application example, the effect of three volatile anesthetics, halothane, enflurane, and isoflurane, on the viability of three commercially available cell lines (A549--human lung carcinoma, HTC-rat hepatoma, MDCK--Madin-Darby canine kidney) was investigated. After exposure to haloalkyl vapors (3%) for 6 and 24 h, respectively, significantly increased LDH levels versus controls, indicating cellular membrane damage, were detected in A549 and hepatoma cells after exposure for 24 h. Hepatoma cells showed a significant LDH release also after 6 h exposure to isoflurane. On the other hand, LDH release from MDCK cells was not significantly different from controls even after 24 h of continuous exposure to any of the tested anesthetics.

Anesthetics, Inhalation↗
PubMed1998

Total colourblindness is caused by mutations in the gene encoding the alpha-subunit of the cone photoreceptor cGMP-gated cation channel.

Total colourblindness (OMIM 216900), also referred to as rod monochromacy (RM) or complete achromatopsia, is a rare, autosomal recessive inherited and congenital disorder characterized by photophobia, reduced visual acuity, nystagmus and the complete inability to discriminate between colours. Electroretinographic recordings show that in RM, rod photoreceptor function is normal, whereas cone photoreceptor responses are absent. The locus for RM has been mapped to chromosome 2q11 (ref. 2), however the gene underlying RM has not yet been identified. Recently, a suitable candidate gene, CNGA3, encoding the alpha-subunit of the cone photoreceptor cGMP-gated cation channel, a key component of the phototransduction pathway, has been cloned and assigned to human chromosome 2q11 (refs 3,4). We report the identification of missense mutations in CNGA3 in five families with RM. Homozygous mutations are present in two families, whereas the remaining families show compound heterozygous mutations. In all cases, the segregation pattern of the mutations is consistent with the autosomal recessive inheritance of the disease and all mutations affect amino acids that are highly conserved among cyclic nucleotide gated channels (CNG) in various species. This is the first report of a colour vision disorder caused by defects other than mutations in the cone pigment genes, and implies at least in this instance a common genetic basis for phototransduction in the three different cone photoreceptors of the human retina.

Base Sequence↗
PubMed1998

[Laughing gas as the principle substance in assessing occupational exposure to inhalation anesthetics].

PURPOSE: In the Federal Republic of Germany limits for the chronic exposure to nitrous oxide and volatile anaesthetics have been prescribed by legislation. According to the technical rules for the handling of hazardous substances TRGS 402 it is legal to measure a single substance in a mixture of hazards, unless the behaviour of all substances is known. Studies about corresponding concentrations of nitrous oxide and volatile anaesthetics in anaesthetic working areas have not yet been carried out. METHODS: During one working week each the concentrations of nitrous oxide, enflurane and desflurane were measured by infrared spectrometry in a working area equipped with air condition and in a non-ventilated operating theatre. Corresponding concentrations of nitrous oxide were measured from the same gas samples. RESULTS: Statistical calculations showed linear correlations of the enflurane and nitrous oxide concentrations in all anaesthetic areas. No linear regression was found between the desflurane and nitrous oxide concentrations. In the working area where desflurane anaesthesias were carried out, significantly higher concentrations of nitrous oxide were observed. Nevertheless the Chi2-test showed no significant differences in the distribution of categorised measurement values. DISCUSSION: Although it is not possible to calculate desflurane concentrations from the nitrous oxide concentrations, measurement of nitrous oxide as leading substance is a valid procedure to assess the exposure of the anaesthesiology workplace to nitrous oxide and volatile anaesthetics. Significant higher nitrous oxide concentrations during desflurane anaesthesia result from early extubation of patients expiring higher concentrations of nitrous oxide.

Air Pollution, Indoor↗
PubMed1998

[The effect of total intravenous anesthesia with propofol, alfentanil and vecuronium (TIVA) on bronchial mucosal transport].

PURPOSE: The mucociliary escalator of the lung is an important protective transport system by means of which inhaled particles and microorganisms are removed from the tracheobronchial system. In the present prospective study the effect of total intravenous anaesthesia with propofol, alfentanil, vecuronium, and oxygen-air ventilation on bronchial mucus transport velocity (BTV) was investigated. METHOD: 10 patients undergoing major abdominal surgery were included in the study. In all patients anaesthesia was induced and maintained with propofol, alfentanil, and vecuronium. Ventilation was assisted with a mixture of air and oxygen (FiO2:0.35). The BTV was measured preoperatively in the conscious patients one day before surgery while they received local anaesthesia with 10 ml of 1 percent lidocaine and after the end of the operation during intubation anaesthesia. BTV was determined with a small volume of albumin microspheres labelled with technetium -99m, which was deposited on the dorsal surface at the lower ends of the right and left main bronches via a catheter placed in the inner channel of a fibre-optic bronchoscope [7]. The study was approved by the ethics committee of our hospital. RESULTS: The administered dose of propofol was 3.0 g (1.8-5.5), of alfentanil 26 mg (20-50), and of vecuronium 20 mg (16-34) (median with range). The duration of mechanical ventilation up to the time of measurement was 5 h (3.0-9.5). TIVA produced a decrease of BTV in the right (9.7 vs 4.9 mm/min) and left main bronchus (11.3 mm/min vs 5.3 mm/min). CONCLUSIONS: Total intravenous anaesthesia with propofol, alfentanil, and vecuronium depressed mucociliary flow in patients with healthy lungs. The period for recovery of mucociliary clearance and the possible disadvantage in patients with increased pulmonary risk (e.g. patients with chronic bronchitis and abdominal surgery) should be clarified in further studies.

Adult↗
PubMed1997

[Combination anesthesia and bronchial tranport velocity. Effects of anesthesia with isoflurane, fentanyl, vecuronium and oxygen-nitrous oxide breathing on bronchial mucus transport].

UNLABELLED: The mucociliary escalator of the lung is an important protective transport system by means of which inhaled particles and microorganisms are removed from the tracheobronchial system. In general, it is assumed that anaesthetics inhibit mucociliary clearance [3,5,6,19,27]. In the present prospective study the effect of combination anaesthesia with isoflurane, fentanyl, vecuronium, and nitrous oxide-oxygen mixture on bronchial mucus transport velocity (BTV) was investigated. PATIENTS AND METHODS: 10 patients undergoing major abdominal surgery were included in the study. The study was approved by the ethics committee of our hospital. In all patients anaesthesia was induced with propofol (1-2 mg/kg), fentanyl (0.2-0.3 mg/kg) and vecuronium (0.1 mg/kg). After intubation anaesthesia was maintained with 1.5 MAC isoflurane and repeated doses of fentanyl (0.1-0.2 mg) and vecuronium. Ventilation was assisted with a 2:1 mixture of nitrous oxide and oxygen. The BTV was measured preoperatively in the conscious patients one day before surgery while they received local anaesthesia with 10 ml of 1 percent lidocaine and postoperatively while they received intubation anaesthesia. BTV was determined with a small volume of albumin microspheres labeled with technetium-99m, which was deposited on the dorsal surface at the lower ends of the right and left main bronchi via a catheter placed in the inner channel of a fibre-optic bronchoscope [15]. RESULTS: Table 1 provides information about age, application of anaesthetics and duration of mechanical ventilation of the patients. The preoperative and postoperative BTV values showed no significant differences (Fig. 1). CONCLUSIONS: Combination anaesthesia with isoflurane, fentanyl, vecuronium, and O2:N2O does not influence BTV in patients with healthy lungs.

Adult↗
PubMed1997

[Effectiveness of anesthetic gas scavengers fulfilling EN 740 requirements with reference to equipment leakage and fresh gas flow].

PURPOSE: During inhalation anaesthesia, contaminations of the working environment be anaesthetic volatiles and nitrous oxide occur. The amount of leaking gases is influenced by leakages of the anaesthetic ventilator, by fresh-gas flows and by the effectivity of the scavenging system. Since 1st January 1996 new ventilators have to be equipped with scavenging devices according to the European standard EN 740. We measured the effectivity of this system with anaesthetic ventilators of a type that is now superseded (mean leakage rate 100 ml/min) and recent devices (mean leakage rate 5 ml/min) using high and low fresh-gas flows. MATERIAL AND METHODS: The anaesthetic ventilators were placed in a non-air-conditioned area. A test lung was ventilated with gas flows of 1 l/min, 3 l/min and 6 l/min (concentrations of nitrous oxide 70%, Enflurane 1%). The ventilation time in each case was 1 h. The minute volume was set to 8 l/min. At 2-minute intervals the concentrations of nitrous oxide and enflurane were measured by a multigas monitor Brüel & Kjaer 1302. The experiments were carried out with an old scavenging device according to DIN 13260 and a new device according to EN 740. RESULTS: Using the scavenging device according to DIN 13260, the concentrations of the pollutant gases were significantly dependent on the fresh-gas flows. No differences were found when using old or new anaesthetic ventilators. Medians of nitrous oxide (n2o) and Enflurane (e): 6 l/min: (n2o) 204 ppm (e) 4.3 ppm 3 l/min: (n2o) 115 ppm (e) 2.1 ppm 1 l/min: (n2o) 61 ppm (e) 0.97 ppm. Scavenging devices according to EN 740 significantly reduced the amount of emitted pollutants. No dependency on fresh-gas flows could be detected. 6 l/min: (n2o) 11.25 ppm (e) 0.05 ppm 3 l/min: (n2o) 10.12 ppm (e) 0.0 ppm 1 l/min: (n2o) 9.5 ppm (e) 0.0 ppm. CONCLUSIONS: The formerly reported dependence of the room air concentrations of anaesthetic volatiles and nitrous oxide from the fresh gas flow are caused by the spillage of pollutants through scavenging devices according to DIN 13260. The use of systems according to EN 740 is not only useful in new devices but must also be recommended for superseded models of anaesthetic ventilators.

Air Pollutants, Occupational↗
PubMed1997

[Pollution of the work environment by volatile anesthetics and nitrous oxide].

Anaesthetic personnel is exposed to different workload conditions. The individual impact is influenced by external factors and human stress stability. Different symptoms reported to be present in anaesthetic personnel are comparable to symptoms of the sick building syndrome, defined by the WHO in the 90's. They are caused by work-induced distress and the exposure to chemical hazards. In anaesthesia, health defects by anaesthetic vapours and gases have been deplored for many years. After the Russian anaesthesiologist Vaisman published a report in 1967, controlled studies concerning cancerogenicity and teratogenicity of volatile anaesthetics under workspace conditions were carried out. In 1989, time-weighted average exposure threshold limit values of 5 ppm were released in the Federal Republic of Germany for halothane. In 1993 thresholds for enflurane (20 ppm) and nitrous oxide (100 ppm) were released. TLV concentrations for the new anaesthetic agents desflurane and sevoflurane have not yet been defined by authorities. Factors influencing workplace concentrations of anaesthetic gases are the anaesthetic procedures, apparatus leakage, air conditioning, fresh gas flow and the function of the scavenging system. Although cancerogenicity, mutagenicity, teratogenicity and reduction of fertility are discussed as effects of chronic exposure to anaesthetic gases, several review articles doubted the results of studies, finding positive correlations of incidence of occupational disease and the exposure to the volatile and gaseous substances. Mainly coexisting factors like smoke-induced exposure to polybromated biphenyls, disturbance in circadian rhythm, stress and enclosure in narrow exposure systems, increasing teratogenicity and cancerogenicity in animal experiments, are considered to promote unreliability of the studies. All reviewers do not discuss the fact, that all of these co-factors are present in the reality of the anaesthetic workplace. Thus, the studies by Corbett, enthusiastically criticized by different reviewers, simulate the all-day reality of the anaesthetic workplace more precisely than controlled experiments conducted, for example, by Eger and co-workers. The results of animal experiments and retrospective studies therefore do not justify realization of large controlled prospective studies but require the overall revision of the anaesthesiological workplace and the reduction of occupational waste gas exposure to the lowest possible levels below all chronic exposure threshold values.

Air Pollutants, Occupational↗
PubMed1997

Effects on haemodynamics and catecholamine release of xenon anaesthesia compared with total i.v. anaesthesia in the pig.

In order to investigate haemodynamic response and catecholamine release during anaesthesia with xenon, we conducted a study on 28 pigs which were allocated randomly to one of four groups: total i.v. anaesthesia with pentobarbitone and buprenorphine, and xenon anaesthesia with inspiratory concentrations of 30%, 50% or 70%, respectively, supplemented with pentobarbitone. Haemodynamic variables were measured using arterial and Swan Ganz catheters. Depth of anaesthesia was monitored using spectral edge frequency analysis. Plasma concentrations of dopamine, noradrenaline and adrenaline were measured by high pressure liquid chromatography. All haemodynamic variables and plasma concentrations of dopamine and noradrenaline remained within normal limits. Adrenaline concentrations were reduced significantly in all groups. Xenon anaesthesia was associated with a high degree of cardiovascular stability. Significant reduction in adrenaline concentrations at inspiratory xenon concentrations of 30% and 50% can be explained by analgesic effects of xenon below its MAC value.

Anesthetics, Inhalation↗
PubMed1996

[The effect of a heat and moisture exchanger (HME) on bronchial mucus transport in a closed inhalation anesthesia system].

UNLABELLED: The administration of dry anaesthetic gases for ventilation leads to morphological changes of the tracheobronchial epithelium that may cause postoperative pulmonary complications. Therefore, additional humidification with a heat and moisture exchanger (HME) is suggested for ventilation during anaesthesia, particularly when using semi-open breathing systems. Recommendations concerning the use of a HME in the semi-closed system are controversial. There are no data in the literature as to whether a HME improves mucociliary transport under these conditions. We therefore studied bronchial mucus transport velocity (BTV) with and without the use of a HME in the semi-closed circle system in humans. PATIENTS AND METHODS: The study was approved by the ethics committee of our hospital. In a prospective, randomised trial a total of 22 patients undergoing major abdominal surgery were investigated. In all patients anaesthesia was induced and maintained with midazolam, fentanyl, and vecuronium. After intubation, a HME (BACT/VIRAL HME, Pharma Systems AB, Sweden) was inserted between the endotracheal tube and ventilation tubing in 11 patients; the other 11 were ventilated without a HME and served as controls. Ventilation was assisted with a fresh flow of 3 in a semi-closed system (Dräger Sulla 808 V with an 8 ISO circle system and Ventilog 2 ventilator, Drägerwek AG, Germany) and a 2:1 mixture of nitrous oxide and oxygen. The fresh gas passed through the soda lime canister. At the end of the operation BTV was measured with a small volume of albumin microspheres labeled with technetium Tc99m, which was deposited on the dorsal surface at the lower ends of the right and left main bronchi via a catheter placed in the inner channel of a fibre-optic bronchoscope. RESULTS: The two groups were comparable with regard to age, sex, preoperative lung function, duration of mechanical ventilation, and dose of anaesthetics. There were no statistically significant differences in the BTVs. DISCUSSION: BTV does not improve with the use of a HME in the semi-closed circle system with a fresh gas flow of 31. With modern anaesthesia machines lower fresh gas flows should be administered, whereby the humidity and temperature of the inspired gases are further increased.

Adult↗
PubMed1996

[The effect of anesthetic method on enflurane air pollution in non-air conditioned operating rooms].

UNLABELLED: Pollution of work areas by volatile anaesthetics and nitrous oxide occurs during general anaesthesia. Short anaesthesia procedures are often carried out in operating theatres that are not equipped with air-conditioning systems. Methods of lowering exposure during short procedures, where mask anaesthesia is the usual procedure, are double masks and the laryngeal mask. The aim of our investigation was to determine the possibility of lowering the pollution of the environment to below national and international thresholds in a non-air-conditioned work area and to find out which method of anaesthesia is the most effective in environmental protection, i.e. which has the lowest leakage rate. METHODS: In our investigation, at two points of the work area the mean enflurane [2-chloro-1-(difluor-omethoxy)-1,1,2-trifluoro-ethane] concentrations were measured under daily routine conditions in a non-ventilated anaesthesiological work area by a gas chromatography. Anaesthesia with single masks, double masks, laryngeal masks or endotracheal intubation was carried out. RESULTS: No differences were found in the mean concentration of enflurane during the anaesthesia procedures. The leakage rates of endotracheal intubation anaesthesia were the lowest. DISCUSSION: In unventilated work areas, it was not possible to lower the exposure of the personnel by changing the method of anaesthesia. The application of procedures like double or laryngeal masks does not avoid the need for installation of air-conditioning systems in all work areas were anaesthesia is performed.

Air Conditioning↗
PubMed1996

Diffusion of anaesthetic gases through different polymers.

BACKGROUND: Improvement of working conditions and anaesthesia with closed systems includes reduction of gas leaks during anaesthesia. One source of contamination is the permeation of gases through plastic materials. The volume of gas permeating through a polymer depends on its molecular structure, the solubility and the diffusion coefficient. METHODS: We designed an experimental set-up to measure the permeation rates of nitrous oxide, enflurane and isoflurane through components of the anaesthetic ventilator made of silicone, latex, rubber and polyvinylchloride (PVC). Reservoir bags, ventilation tubes and endotracheal tubes were investigated. RESULTS: The highest permeation rates of anaesthetic gases were observed with silicone materials. Permeation through silicone exceeded that of the least permeable material by more than 10.000 times. By summarizing the permeation rates of the single items, the use of silicone increases the anaesthetic system's leakage rate by 4 ml/min, which means an increase of 18% in a modern anaesthetic ventilator and of 31% in a closed system. CONCLUSIONS: The highest permeation rates were found for nitrous oxide through silicone, although nitrous oxide has a known low solubility in plastic materials. The result demonstrates the dependency of the leakage rate on the diffusibility. The leakage of anaesthetic gases caused by silicone items does not alone lead to unacceptable pollution of operating theatres. To minimize the total leakage rates of minimal-flow-systems, however, plastic materials with low solubility and low diffusion coefficients have to be used.

Anesthesia, Inhalation↗
PubMed1996

Geriatric education in osteopathic medical schools.

To determine if the curricula at the colleges of osteopathic medicine (COMs) are adequately preparing their graduates to meet the challenge of the geriatric demographic imperative, the authors surveyed the 16 COMs using a modified version of a survey conducted by Karuza and colleagues. Results were compared with those obtained from the Karuza and colleagues' survey of 73 allopathic medical schools. Overall, 88% of the COMs reported that they were committed to teaching geriatrics to undergraduate medical students, compared with 72% of the allopathic medical schools. Lack of time and appropriate clinical facilities were the two greatest barriers to committing more time to geriatrics in both osteopathic and allopathic undergraduate medical training programs.

Education, Medical, Undergraduate↗
PubMed1995

Ultrastructure and mucociliary transport of bronchial respiratory epithelium in intubated patients.

OBJECTIVE: The objective of this study was to investigate whether reduced bronchial mucus transport velocity (BTV) is associated with a loss of cilia or ultrastructural abnormalities of cilia in intubated patients. DESIGN: The patients were studied prospectively in a convenience sample trial. SETTING: The study took place in a university hospital. PATIENTS AND PARTICIPANTS: 29 orally intubated patients in a surgical ICU. INTERVENTIONS: BTV was measured with radiolabeled microspheres in the right and left primary bronchus. Following these measurements, biopsy samples were taken from the bronchi for scanning (SEM) and transmission (TEM) electron-microscopic investigations. MEASUREMENTS AND RESULTS: SEM: Patients with normal or slight impaired BTV (group 1, n = 14: BTV: 8.5 mm/min (3.8-11.5); median with range) showed more cilia on the luminal surface than patients with markedly depressed BTV (p < 0.05) (group 2, n = 15: BTV: 0 (0-2.1)). The difference was statistically significant. The BTV values correlated moderately with the number of cilia on the luminal surface (r = 0.46; p = 0.02). TEM: In group 1, 6.5% (3.9-14.9) of cilia were abnormal (median with range) vs 9.3% (4.9-13.7) in group 2; these differences were not statistically significant. Neither was there any significant correlation between BTV and the frequency of abnormal cilia. CONCLUSIONS: Impaired mucociliary transport in intubated patients is associated with a loss of cilia rather than ultrastructural abnormalities of cilia, which are less relevant.

Adult↗