Performances and limits of Bag-Valve-Device for pre-oxygenation and manual ventilation: A comparative bench and cadaver study.

INTRODUCTION: Bag-Valve-Device (BVD) is the most frequently used device for pre-oxygenation and ventilation during cardiopulmonary resuscitation (CPR). A minimal expired fraction of oxygen (FeO2) above 0.85 is recommended during pre-oxygenation while insufflated volume (VTi) should be reduced during manual ventilation. The objective was to compare the performances of different BVD in simulated conditions. METHODS: Nine BVD were evaluated during pre-oxygenation: spontaneous breathing patients were simulated on a test lung (mild and severe conditions). FeO2 was measured with and without positive end-expiratory pressure (PEEP). CO2 rebreathing was evaluated. Then, manual ventilation was performed by 36 caregivers (n = 36) from three hospitals on a specific manikin; same procedure was repeated by 3 caregivers (n = 3) on two human cadavers with three of the nine BVD: In non-CPR scenario and during mechanical CPR with Interrupted Chest Compressions strategy (30:2). RESULTS: Pre-oxygenation: FeO2 was lower than 0.85 for three BVD in severe condition and for two BVD in mild condition. FeO2 was higher than 0.85 in eight of nine BVD with an additional PEEP valve (PEEP 5 cmH2O). One BVD induced CO2 rebreathing. Manual ventilation: For non-CPR manual ventilation, mean VTi was within the predefined lung protective range (4-8 mL/kg PBW) for all BVD on the bench. For CPR manual ventilation, mean VTi was above the range for three BVD on the bench. Similar results were observed on cadavers. CONCLUSIONS: Several BVD did not reach the FeO2 required during pre-oxygenation. Manual ventilation was significantly less protective in three BVD. These observations are related to the different BVD working principles.

Gammagrafía con 75Se-ácido tauroselcólico (75SeHCAT(R)), ¿prueba de referencia en la malabsorción de ácidos biliares? / 75Se-Homocholic acid taurine scintigraphy (75SeHCAT(R)), a standard benchmark test in bile acid malabsorption?

La diarrea crónica por malabsorción de ácidos biliares (MAB) es una patología infradiagnosticada. Se dispone de diferentes herramientas diagnósticas, aunque en la actualidad no existe consenso sobre cuál de estas sería la prueba de referencia o gold standard. En esta revisión se valora la posibilidad de utilizar la gammagrafía con 75Se-ácido tauroselcólico (75SeHCAT(R)) como prueba diagnóstica de referencia y su perspectiva de futuro. Se realizó una búsqueda bibliográfica en Pubmed y OVID, obteniéndose un total de 57 trabajos y usándose finalmente 26 de ellos tras ser seleccionados bajo los conceptos de gold standard, exactitud diagnóstica y otros biomarcadores. Valoramos las ventajas e inconvenientes de las diferentes herramientas diagnósticas: 14C-glicocolato, medición de ácidos biliares en heces, C4 en suero, FGF19 en suero, colestiramina y gammagrafía con ácido tauroselcólico. Consideramos que la gammagrafía con 75SeHCAT(R) es la prueba diagnóstica más recomendada en Europa para el diagnóstico de MAB al presentar los índices más elevados de sensibilidad y especificidad. Presenta una gran relación coste-beneficio, por lo que es la prueba con mayor grado de recomendación. Sin embargo, aún no es posible su uso de forma reconocida como gold standard debido a la falta de estudios que proporcionen datos concluyentes que permitan su consenso. Mientras tanto, se podría aconsejar el uso combinado de la prueba con colestiramina en todos los pacientes que queramos evaluar, independientemente del resultado gammagráfico, como uso de patrón de referencia

Chronic diarrhoea due to bile acid malabsorption (BAM) is an underdiagnosed pathology. Different diagnostic tools are available. However, there is currently no consensus on which of these would be the benchmark test or gold standard. This review evaluates the possibility of using 75Se-taurocholic acid (75SeHCAT(R)) scintigraphy as a benchmark diagnostic test and its perspective for the future. A literature review was conducted in Pubmed and OVID obtaining a total of 57 papers, 26 of which were finally used after being selected under the concepts of gold standard, diagnostic accuracy and other biomarkers. We evaluated the advantages and disadvantages of the different diagnostic tools: 14C-glycocholate, measurement of bile acids in faeces, C4 in serum, FGF19 in serum, cholestyramine, and 75Se-tauroselcolic acid scintigraphy. We consider that the 75SeHCAT(R) scan is the most recommended diagnostic test in Europe for diagnosing BAM as it presents the highest values of sensitivity and specificity. It has a significant cost-benefit ratio, making it the test with the highest degree of recommendation. However, it is still not possible to use it in a recognised way as a gold standard due to the lack of studies that provide conclusive data that allow consensus. In the meantime, the combined use of cholestyramine testing in all patients we want to evaluate, regardless of the scintigraphy result, could be encouraged as a benchmark standard

75Se-Homocholic acid taurine scintigraphy (75SeHCAT®), a standard benchmark test in bile acid malabsorption? / Gammagrafía con 75Se-ácido tauroselcólico (75SeHCAT®), ¿prueba de referencia en la malabsorción de ácidos biliares?

Chronic diarrhoea due to bile acid malabsorption (BAM) is an underdiagnosed pathology. Different diagnostic tools are available. However, there is currently no consensus on which of these would be the benchmark test or gold standard. This review evaluates the possibility of using 75Se-taurocholic acid (75SeHCAT®) scintigraphy as a benchmark diagnostic test and its perspective for the future. A literature review was conducted in Pubmed and OVID obtaining a total of 57 papers, 26 of which were finally used after being selected under the concepts of gold standard, diagnostic accuracy and other biomarkers. We evaluated the advantages and disadvantages of the different diagnostic tools: 14C-glycocholate, measurement of bile acids in faeces, C4 in serum, FGF19 in serum, cholestyramine, and 75Se-tauroselcolic acid scintigraphy. We consider that the 75SeHCAT® scan is the most recommended diagnostic test in Europe for diagnosing BAM as it presents the highest values of sensitivity and specificity. It has a significant cost-benefit ratio, making it the test with the highest degree of recommendation. However, it is still not possible to use it in a recognised way as a gold standard due to the lack of studies that provide conclusive data that allow consensus. In the meantime, the combined use of cholestyramine testing in all patients we want to evaluate, regardless of the scintigraphy result, could be encouraged as a benchmark standard.

Lipid composition of hepatocyte plasma membranes from geese overfed with corn.

Twelve-week-old Landes male geese were overfed with corn for 21 d in order to induce liver steatosis (fatty liver). Lipid composition of hepatocyte plasma membranes from fatty livers was compared to that of lean livers obtained from geese fed a normal diet. The ratio cholesterol/phospholipids was higher in fatty hepatocyte plasma membranes (0.63 vs. 0.47), whereas the phospholipid/protein ratio was less than half. Overfeeding induced changes in fatty acid composition of hepatocyte plasma membranes, including a greater than twofold increase in the percentage of oleic acid (29.7 vs. 13.8%) and a somewhat lesser increase in lauric, palmitic, and palmitoleic acid contents of plasma membrane lipids of fatty livers. A concomitant reduction in the proportion of stearic acid (18.4 vs. 25.1%) was also observed. In fatty livers, the increased ratio of saturated to polyunsaturated fatty acids (PUFA) (1.5 vs. 1.0) was related to a significant decrease in PUFA content. Among all the PUFA, only the eicosatrienoic acid (20:3n-9) percentage was increased by liver steatosis. Overfeeding with corn appeared to induce competition between de novo synthesized and dietary fatty acids incorporated in hepatocyte plasma membranes. This resulted in an accumulation of de novo synthesized monounsaturated and derived fatty acids in plasma membranes from overfed birds. A defect in the incorporation of linoleic acid and linoleic- and linolenic-derived PUFA was observed despite the high proportion of these essential fatty acids in the diet. It was concluded that in overfed palmipeds, de novo hepatic lipogenesis prevails over dietary lipid intake to modulate lipid composition of the fatty liver plasma membrane.

[Relationship between digestive repletion state and hepatic composition in gavaged mule ducks]. / Relation entre l'état de réplétion digestive et la composition hépatique du canard mulard en gavage.

Two batches of male mule ducks were constituted on the basis of the filling state of the crop at slaughter, after being over-fed twice a day for 5 days: no corn in the crop defined 'OV' birds, and corn in the crop defined 'OP' birds. 'OP' animals presented significantly lower daily consumption during the last 3 days of force-feeding. They had a lighter liver weight than 'OV' ducks (178 versus 197 g), lower hepatic lipid percentages (25.0 versus 33.0%), and enhanced hepatic glycogen rates (4.7 versus 2.4%). Metabolic state of animals might explain these variations in hepatic composition. Unadaptation to force-feeding modifies the metabolic inbalance of the overfed animals and consequently induces higher levels of carbohydrate. These results suggest that similar differences between crude fatty livers could be reflected in the quality of the cooked products.

[In vitro simulation of rabbit cecal fermentation in a semi- continuous flow fermentor. III. Effect of the quantity of dry matter introduced daily in the fermentor and reproducibility of the method]. / Simulation in vitro des fermentations caecales du lapin en fermenteur à flux semi-continu. III. Effet de la quantité de matière sèche introduite quotidiennement dans le fermenteur et reproductibilité de la méthode.

In a preliminary experiment, 3 Rusitec-like fermentors of 1 L capacity were operated under identical conditions. The only difference was the quantity to treated substratum introduced daily into each fermentor: 15 g/d (M15); 40 g/d (M40); and 60 g/d (M60) on a dry matter basis. The fermentation substratum was a rabbit feed that had been digested with amylase and pepsin. The organic matter was lost over 48 h at a significantly higher rate in the M15 fermentor than in M40 and M60: 30.4%, 19.7% and 17.3%, respectively. The pH values observed in M40 and M60 (5.99 and 5.83) were similar to that observed in vivo under ad libitum feeding conditions. The pH was higher in M15 (6.7), as observed in vivo with restricted animals just before the daily meal. The volatile fatty acids (VFA) proportions for C2, C3 and C4 were similar to the in vivo proportion for the 3 fermentors. The daily total VFA production was the largest with M40 but was associated with a poor stability and an excess of minor VFAs. The introduction of 15 g/d was preferred by the authors because of organic matter disappearance rate, pH stability and VFA production. In a second experiment, 4 fermentors were used in the same way as the M15 one, in order to study the reproducibility of the method. Small but significant differences between fermentors were observed for all parameters in relation to a high fermentor stability from 1 day to the next.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of coconut oil in the post-weaning starter diet on growth and carcass qualities of male lambs, weaned early and intensively fattened in winter.

The influence of medium-chain fatty acids (5% coconut oil) introduced in a starter diet (ALc) for 21 d after weaning was investigated in 230 Lacaune male lambs. They were weaned early, intensively fattened during winter and slaughtered at a constant live-weight (39 kg). Comparisons have been made regarding the individual growth rates and carcass qualities with an isocaloric and isonitrogenous reference diet (ALr) from lamb sub-samples. During the period of actual starter diet utilization, ALc induced a higher growth rate (+ 59%) independently of the weaning weight (Wto). The feed conversion ratio was lower with ALc (P < 0.01). The induced weight difference remained after the lambs were fed on the same finishing diet. The growth pattern for the entire fattening period was more regular with ALc, particularly when lamb weight was medium (12 kg) of light (Wto < 11 kg) at weaning. The volatile fatty acid pattern in the rumen fluid over time (sampling with a rumen vacuum pump) and throughout the transition between starter and fattening diets (Rusitec procedure) did not show a clear coconut oil effect. ALc induced a slight increase in the external fat layer at slaughter 2 months later, especially in heavy lambs. Firmness and colour of subcutaneous fatty tissue were not different, but ALc tended to result in firmer and whiter carcasses in the case of the heavier lambs at weaning.

[In vitro simulation of rabbit cecal fermentation in a semi- continuous flow fermentor. I. Role of food substrate pretreatment]. / Simulation in vitro des fermentations caecales du lapin en fermenteur à flux semi-continu. I. Rôle du prétraitement du substrat alimentaire.

A Rusitec semi-continuous flow fermentor was used to study the influence of enzyme pretreatment of food substrates on the fermentation profile over a 2-week period following inoculation with rabbit caecal contents. Three types of substrate were examined: 1) homogenized commercial rabbit feed; 2) the solid remains of this feed after digestion with alpha-amylase for 24 h; and 3) substrate 2 digested for 4 h with pepsin (double enzyme treatment). One of a pair of nylon pouches containing 15 g substrate was replaced each day, thus producing a uniform 48-h fermentation. Fermentation of the untreated feed (1) for 5-6 days produced a fermentation profile quite different from that obtained in vivo in the rabbit caecum: propionic acid accounted for over 35% of total volatile fatty acid (VFA), and butyric acid for about 15%. Amylase digestion (2) gave a stable ferment profile closer to the in vivo profile, except that propionic and butyric acids were similar at 15% of total VFA. Digestion with both amylase and pepsin (3) produced a stable fermentation profile very close to the in vivo profile: C2 > 60%, C3 < 11% and 17% < C4 < 21%. The rate at which membrane constituents (acid detergent fibre, ADF) were lost in 48 h was similar to the digestibility coefficient measured in vivo by others for the same basic feed. Lastly, there was a high percentage (about 5%) of volatile C5 fatty acids; this could be due to the discontinuous fermentor input of one pouch per 24 h. Thus, feed pretreated with both amylase and pepsin simulates, in vitro, rabbit caecal fermentation in a semi-continuous Rusitec type fermentor.

[In vitro simulation of rabbit cecal fermentation in a semi- continuous flow fermentor. II. Effect of inoculum type]. / Simulation in vitro des fermentations caecales du lapin en fermenteur à flux semi-continu. II. Effet de la nature de l'inoculum.

Two Rusitec fermentors were operated under identical conditions. One was seeded with an inoculum of rabbit caecal contents, and the other with bovine rumen contents. The fermentation substrate was rabbit feed that had been digested with amylase and pepsin. The substrate constituents (organic matter, OM and NDF) were lost in 48 h at a significantly higher rate in the presence of rumen inoculum (OM: +10%, NDF: +15%). The pHs of the 2 fermentors were similar at pH 6.6. The fermentors produced similar amounts of protein nitrogen per 24 h, after 6 d of adaptation. Volatile fatty acid production was slightly higher in the presence of rumen inoculum. The fermentor inoculated with rumen contents produced a higher percentage of propionic acid (25%) than of butyric acid (7%), while fermentation with rabbit caecal contents gave the opposite ratio (C3/C4 = 0.81). Consequently, only the rabbit caecal inoculum provided the fermentation profile characteristic of the species.

Effects of intraluminal nutrients on intestinal myoelectric activity in rabbits.

In the unanesthetized rabbit, intraluminal infusions of D- and L-methionine, L-tryptophan, D-glucose, D-xylose, and lactulose had a biphasic effect on small intestinal myoelectric activity. A phase of enhanced activity was followed by a phase of inhibition. The excitatory phase was mimicked by saline solutions equiosmolar to the test solutions. The subsequent inhibition was does dependent and significantly (P less than 0.01) longer for the passively absorbed D-methionine than for the L-stereoisomer. The inhibitory action of 10 mM D-glucose, 10 mM L-methionine, and 5 mM L-tryptophan was blocked by propranolol on the jejunum and by phenoxybenzamine on the ileum. We conclude that the initial excitatory phase induced by luminal amino acids and sugars may be dependent on an action on osmoreceptors, whereas the subsequent inhibitory phase may involve the sympathetic noradrenergic system.

[Diet type, grinding size and anatomo-functional characteristics of the proximal digestive tract in the rabbit]. / Nature de l'aliment, finesse de mouture et données anatomo-fonctionnelles du tube digestif proximal du lapin.

Two diets containing either dehydrated lucerne (40%) or dehydrated beet pulp (50%) both being coarsely (4 mm) of finely (1 mm) ground before pelleting, were fed to 120 rabbits after weaning. Feed intake and weight gain were estimated. After 79 days, 11 rabbits in each group were slaughtered between 14.00 and 17.00 h. The parameters measured were stomach and ileal weights, dry matter, fibre and nitrogen contents, volatile fatty acid concentrations. Gastric emptying and intestinal transit time were estimated in each group. Rabbits fed the beet pulp diet had a better feed conversion ratio associated with a higher solid matter gastric retention and also a longer jejuno-ileal transit time. Finely ground diet further increased the transit time, particularly in the ileum, which was also associated with a higher concentration of fermentation by-products.

[Physico-chemical stimulation of dietary origin and digestive motility in the rabbit]. / Stimulation physico-chimique d'origine alimentaire et motricité digestive chez le lapin.

The effects on gastrointestinal motility of two different diets, one containing dehydrated lucerne and the other dehydrated beet pulp (both being either coarsely or finely ground before pelleting) were studied in 16 unanesthetized 50-60-day old rabbits fed ad libitum. The rabbits fed with lucerne had better antroduodenal and ileo-caecal coordination, a higher level of electrical activity on the duodenum, and more frequent migrating myoelectric complexes on the jejunum and ileum than those fed with beet pulp. Furthermore, the rabbits fed the finely ground pellets showed weak electrical activity on the ileum and poor ileo-caecal coordination irrespective of fiber source, suggesting a unique effect of size per se on these portions of the digestive tract.

Evidence of a thiamine deficiency in sheep fed maize silage.

Two groups of Merino sheep (with or without rumen fistulae) were used to study the effect of feeding maize-silage (compared to hay) on: thiamine concentrations in rumen fluid, tissues and organ; blood transketolase activity; microbial fermentation in the rumen. After sheep were transferred from a hay diet to maize-silage, thiamine concentrations in ruminal fluid fell to about 25% of control values on hay. Thiamine levels greatly decreased in kidney, heart, liver, rumen tissue and large intestine. Blood transketolase and TPP effect significantly decreased (P less than 0.01). Ruminal ammonia nitrogen and total volatile fatty acid (VFA) concentrations were not affected by the two diets. However, both butyric acid and isovaleric acid were significantly higher (P less than 0.001) in rumen fluid of sheep fed maize-silage. No significant differences were detected between diets for ruminal thiaminase activity regardless of the time of sampling. Relationships between butyric fermentation, thiaminase activity in maize-silage diet and a possible role of Clostridium are discussed. It was concluded that there is a marked thiamine deficiency in sheep fed maize-silage; the factors involved need further study.

[Influence of thiamine on bacterial proteosynthesis in sheep]. / Influence de la thiamine sur la protéosynthèse bactérienne chez le mouton.

To determine the effect of thiamin on the activity of rumen microorganisms we measured the extent of bacterial protein synthesis by in vitro incubations in the presence of filtered rumen juice and a protein-free purified diet with 4 p. 100 urea. This was verified by the amount of protein formed in the incubation medium. Comparing the process in the absence of thiamin, the incorporation of that vitamin at the rate of 4 mg/g resulted in a mean increase of 65 p. 100 of the bacterial proteins synthesized in vitro in 3 hrs. Parallel to this thiamin effect on protein synthesis, the fatty acid analysis showed a modification of the microbial aspect with increased formation of propionic acid (p. 100 of C3 for diet with thiamin vs p. 100 of C3 for the thiamin-free diet = 40.39 +/- 5.08 vs 25.12 +/- 2.99). This was an improvement of energetic yield following the stochiometric calculations. These observations might explain the effect of this additive nutrient on rumen bacterial proteosynthesis.

[Changes in the digestibility of constituents of the diet in the rabbit]. / Variations de la digestibilité des constituants de la ration chez le lapin.

Fiber digestibility of two diets (the first based on alfalfa dried, the second based on beet-pulp dried) with the same level of crude fiber and crude protein was measured on rabbits of 6, 7, 11, 13 and 17 weeks old. The age has no significative effect on digestibility (dry matter, organic matter, crude fiber) of the two experimental diets. The quantity of cellulose and hemicellulose digested was greater in rabbits on the pulp diet. Independantly of the diet hemicellulose is more digestible than cellulose. Expediency of use other analytical test than crude fiber in the nutritional requirements of rabbits is discussed.

[Cecal motricity and ceco-iliac transit in the horse]. / Motricité caecale et transit caeco-colique chez le chaval

Electrical spiking activity of the caecum is increased eight-fold and the rate of passage of digesta is increased four-fold when the volume of caecal contents is doubled. The role of caecal motility in regulating the volume of caecal contents is discussed.