Clinical experience of paediatric self-expanding foam cuffed tracheostomy tubes.

INTRODUCTION: Use of self-expanding foam-filled tracheostomy tube cuffs (Bivona® FOME cuf®) in paediatrics has become a recent practice within our institution for patients with intractable aspiration. The current literature, clinical indications and subsequent management is lacking. We present our experience with a cohort of children with a foam-cuffed tracheostomy tube managed at Great Ormond Street Hospital, describing their indications and outcomes, as well as routine and emergency management. METHOD: Our tracheostomy patient population was reviewed and those with a Bivona® FOME cuf® tracheostomy tube were identified and reviewed. The indications for foam-cuffed tracheostomy tube insertion, progress, and further management, including emergency care, were reviewed. RESULTS: Ten patients were identified, all with a chronic history of respiratory infections secondary to aspiration being the leading indication. All patients had an ongoing improvement in their chest function following insertion with no episodes of cuff trauma. One patient had difficulty when a port line was accidently cut, which resulted in difficulty of removal, and we outline a strategy for dealing with this. CONCLUSION: The foam-cuffed tracheostomy tube is a useful tracheostomy tube to use in the management of chronic aspiration in children with poor chest health, however due to the lack of knowledge and experience they can prove to be a difficult tube to manage. Further educational information should be available as to the indications, routine care and emergency management of Bivona® FOME cuf® tracheostomy tubes. We believe they represent a useful option for institutions to consider in the paediatric population.

Nucleotide sequence of diatom plasmids: identification of open reading frames with similarity to site-specific recombinases.

We have determined the nucleotide sequence of two small circular DNA plasmids, pCf1 and pCf2 [22], from the marine diatom Cylindrotheca fusiformis. pCf1 is 4273 bp, and pCf2 is 4079 bp in size. In each plasmid, all of the major open reading frames (ORFs) are encoded on the same DNA strand. Two ORFs are similar, comparing the two plasmids. ORF218 (pCf1) and ORF217 (pCf2) share 80% amino acid identity and ORF482 (pCf1) and ORF484 (pCf2) share 54% amino acid identity. ORF218/217 shows significant similarity (28-31% amino acid identity) to the Tn3 class of resolvases. Resolvases are most commonly found in bacterial transposons. However, two other features found in the Tn3 class of transposon are missing in the plasmids; an ORF encoding a transposase and terminal inverted repeat sequences. This, and data mapping the portions of the plasmids that hybridize to genomic chloroplast DNA, suggest that the plasmids do not contain active transposons. By analogy with the R46 plasmid from Enterobacter [5, 6], another potential role for the resolvases encoded by pCf1 and pCf2 is the conversion of multimeric forms of the plasmid to monomers. The similarity of ORF218/217 to resolvases documents the first identification of a potential coding function in an algal plasmid.

Liquid chromatography and fluorescence detection of vitamin A in animal feeds, finished feeds, and premixes.

A simple liquid chromatographic method for vitamin A (retinol) in animal feeds is described. The feed is saponified, diluted to minimize interferences, and extracted into petroleum ether with a single step. The analysis is sensitive and specific with liquid chromatography and a fluorescence detector. The minimum level of detection is 15 ng/mL, which is equivalent to 10,000 units/lb vitamin A. The method includes a stable and reproducible standardization of vitamin A that is used to calibrate standard peak heights in terms of units retinol/mL. Guarantees of 10,000 units/lb up to premix levels can be analyzed with good recoveries and precision.

A collaborative study: high-pressure liquid chromatographic determination of carbadox and pyrantel tartrate in animal feeds.

Carbadox (CBX), an antibacterial agent, and pyrantel tartrate (PT), an anthelmintic, are formulated either separately or together in swine feeds. The official Association of Official Analytical Chemists (AOAC) spectrophotometric methods for both drugs are long, nonspecific, and require standard addition techniques. Results by this technique are positively biased. A simple, direct, specific, high-pressure liquid chromatographic (HPLC) method to determine either one or both drugs simultaneously with apparent accuracy and precision is developed. Drugs are released from feed matrices by water, extracted with dimethylformamide (DMF), cleaned up on alumina, and quantitated by direct comparison to standards using a Whatman Partisil 10 ODS-3 column and a mobile solvent containing 23.5 +/- 1.5% DMF in phosphate buffer (pH 2.0). Fourteen laboratories participated in a collaborative study of this method for determination of CBX and PT in animal feeds.

Sample preparation of carbadox, furazolidone, nitrofurazone, and ethopabate in medicated feeds for high pressure liquid chromatography.

Medicated feeds (pelleted or mash) containing guarantees of carbadox, furazolidone, nitrofurazone, and ethopabate are pretreated with water, extracted with 95% dimethylformamide overnight at room temperature, cleaned up on a column of alumina, and injected into a high pressure liquid chromatograph for quantitative measurement. Carbadox, nitrofurazone, and furazolidone can be separated; chromatograms show excellent baseline resolution, and results are in good agreement with colorimetric methods. The same extraction and cleanup can be used to improve colorimetric methods for furazolidone and nitrofurazone.

Rapid colorimetric method for carbadox in animal feeds.

The colorimetric method for carbadox in animal feeds was modified to be simpler and faster. Carbadox is extracted with dimethyl-formamide and separated from interferences on an alumina column in the absence of water by controlling the amount of sample extract on the column and the flow rate. The isolated carbadox is eluted into sodium hydroxide and the resultant yellow chromophor is measured spectrophotometrically at 420 nm.

Agar well technique for antibiotics in animal feeds.

The agar well technique compares favorably with the cylinder plate assay in accuracy, sensitivity, and precision. It is more flexible and more rugged, and growth of seed organism is not inhibited. The wells are precision cut with Grafar gel punch assembly with sets (6) of 10, 7, 5, 4, and 3 mm cutters. The wells are easily and rapidly filled with short, disposable Pasteur pipets fitted with rubber bulbs. The smaller wells are filled with capillary pipets. The diameter of the well (independent of volume) appears to be a function of concentration. For every decrease in the diameter size of the well, concentration can be increased, at least to the next higher level of the standard response line. Extracts of chlortetracycline containing as much as 3.2 mu-g/ml can be analyzed if the 3 mm wells are used and with no sacrifice in accuracy or precision. This works especially well for antibiotic premixes. The technique has been used successfully for penicillin, streptomycin, chlortetracycline, oxytetracycline, oleandomycin, and tylosin.

The effect of splanchnic nerve stimulation on gastric acid secretion and mucosal blood flow in the anaesthetized cat.

1. Electrical stimulation of the vagus nerves produced a parallel increase in gastric acid secretion and gastric mucosal blood flow.2. Gastric acid secretion and mucosal blood flow, stimulated by pentapeptide infusions or by vagal stimulation, were markedly and equally reduced by electrical stimulation of splanchnic nerve fibres.3. The splanchnic stimulated reduction in acid and mucosal blood flow occurred only when the rise in blood pressure, normally associated with splanchnic stimulation, was prevented by inclusion of a pressure reservoir in the circulation.4. There was evidence that the effect of the splanchnic nerves was not mediated by release of adrenaline from the adrenal medulla.