Biomedical subjects
D B Silk
Publications and source records attributed to D B Silk.
Effect of catheter tunnelling and a nutrition nurse on catheter sepsis during parenteral nutrition. A controlled trial.
In a three-year controlled trial of subcutaneous catheter tunnelling as a method of reducing total parenteral nutrition (TPN) catheter sepsis 99 silicone catheters (52 tunnelled, 47 untunnelled) were inserted into the subclavian (94%) or jugular (6%) veins under aseptic conditions. The influence of a nutrition nurse, who joined the nutrition team after 18 months, on catheter sepsis rate was also documented. Catheter sepsis was confirmed in 13 of 47 (28%) untunnelled catheters and only 6 of 52 (11.5%) tunnelled catheters (p less than 0.05). A nutrition nurse reduced sepsis rate from 33% (tunnelled 6, untunnelled 11) to 4% (0 tunnelled; 2 untunnelled) (p less than 0.001). There was no significant difference between tunnelled and untunnelled catheters in sepsis rates after the arrival of the nutrition nurse. Although 85% patients had concurrent internal sepsis, the pathogens implicated in catheter sepsis came from superficial sites in 16 of 19 cases (p less than 0.01). Rigorous aseptic nursing care is thus the most significant factor in the reduction of TPN catheter sepsis, but tunnelling can reduce sepsis rate when nursing care is suboptimum.
The roles of lactose and Clostridium difficile in the pathogenesis of enteral feeding associated diarrhoea.
This study investigated the influence of the disaccharide lactose on the incidence of clinically significant enteral feeding associated diarrhoea. In this double blind study both groups each of 25 patients were randomised to receive either a lactose containing diet Clinifeed 400 in 25 patients or a lactose free diet Ensure in 25 patients. Diarrhoea occurred with equal frequency in both treatment groups, even in those patients with symptomatic and biochemical evidence of impaired lactose handling. Although the onset of diarrhoea was significantly associated with antibiotic administration (p<0.01), Cl. difficile was not isolated from the stools of any patient with diarrhoea.
Clinical indications for weighted enteral feeding tubes.
Simple unweighted fine bore feeding tubes have been used by our Nutritional Support Team for routine nasogastric feeding with success in large numbers of patients. Three clinical situations where mercury or tungsten weighted tubes offer advantages over fine bore tubes have been defined. Significant advantages in patients with concurrent endotracheal intubation, gastric atony and severe oesophageal stricturing are described.
Limitations and drawbacks of 'fine bore' nasogastric feeding tubes.
The clinical use of unweighted nasogastric feeding tubes (n = 491) was compared with that of weighted nasogastric feeding tubes. No advantage was found in the use of the weighted tubes.
A controlled trial of aseptic enteral diet preparation--significant effects on bacterial contamination and nitrogen balance.
This study was performed to evaluate the clinical effectiveness of the 'standard' and aseptic enteral diet preparation techniques and to investigate the relationship between bacterial contamination of diets and symptoms during enteral nutrition. In this controlled study patients were prescribed isonitrogenous polymeric diets prepared using either 'standard' or aseptic techniques, administered by 24 nasogastric infusion. 'Standard' diet preparation resulted in significant bacterial contamination (p<0.01), but this did not increase incidence of diet related symptoms. Use of sterile techniques permitted safe use of large volumes (1.5-2 litre) containers, and this resulted in significantly better nitrogen intake (p<0.05) and balance (p<0.05).
Comparison of an elemental and polymeric enteral diet in patients with normal gastrointestinal function.
In a prospective controlled clinical trial, 70 patients with normal gastrointestinal function were randomised to receive either an elemental diet based on Vivonex HN or an isonitrogenous isocalorie polymeric diet based on Clinifeed 400, administered by continuous 24 hour nasogastric infusion. The two groups of patients were well matched for age, sex, diagnosis, prior starvation, duration of feeding, initial nutritional status, and metabolic status. Nitrogen losses were significantly less on the polymeric feed, despite similar intakes. Serum transferrin rose significantly (1.85 +/- 0.2 to 2.30 +/- 0.2 g/l, p less than 0.05) only in the Clinifeed group, but nutritional parameters were otherwise maintained in both groups. The incidence of diarrhoea (Vivonex, 23.5%; Clinifeed, 30.6%) was not significantly different and was attributable to antibiotics in most cases. Hypokalaemia, which occurred in nearly half the patients, was equally distributed in the two groups, but hypophosphataemia occurred more often in the Vivonex group (p less than 0.05). Liver enzyme disturbances were similar in both groups. The present findings, therefore, provide no evidence that chemically defined 'elemental' diets containing free amino acids as their nitrogen source are in any way superior to polymeric diets containing whole protein and fat when administered to patients with normal gastrointestinal function.
Glucose absorption from starch hydrolysates in the human jejunum.
The intestinal absorption and mucosal hydrolysis of a partial and a complete alpha-amylase hydrolysate of corn starch, simulating the normal intermediary and end products of luminal starch digestion, was studied using an in vivo steady state jejunal perfusion technique in normal human subjects. Alpha-amylase was excluded from the test segment by proximal balloon occlusion. Products of hydrolysis during intestinal perfusion were identified using gel permeation chromatography. Three isocaloric, isotonic sugar saline solutions containing 140 mM glucose, 70 mM maltose and the partial amylase hydrolysate of starch (51.5 +/- 1.4% of glucose content comprising glucose polymers of more than 10 glucose units) were perfused in the first study. Net glucose absorption during perfusion of the partial hydrolysate and free glucose was similar, but significantly faster from maltose (p less than 0.05). Hydrolysis of the polymer fraction containing more than 10 glucose units was significantly slower (29.5 +/- 2.0% of infused load) than the lower molecular weight fraction (56.4 +/- 3.8%, p less than 0.001). As net glucose absorption from the partial hydrolysate was similar to that from glucose, despite the slow hydrolysis of the higher molecular weight fraction, it seemed likely that oligosaccharides in the more rapidly hydrolysed lower molecular weight fractions were exerting a kinetic advantage on glucose absorption. This was confirmed in a second study, where glucose absorption from a complete amylase hydrolysate consisting predominantly of maltose, maltotriose and alpha-limit dextrins, occurred significantly faster (81.8 +/- 4.8 mmol/h/25 cm) than from isocaloric free glucose (55.8 +/- 4.9 mmol/h/25 cm, p less than 0.001). Chromatograms of intestinal aspirates suggested that (1->4), but not 1->6) linked oligosaccharides liberated during luminal and brush-border hydrolysis of dietary starch conferred a kinetic advantage on glucose absorption.
Digestion and absorption of dietary protein in man.
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Endoscopic placement of fine bore nasogastric and nasoenteric feeding tubes.
In a small proportion of patients requiring enteral nutrition it may not be possible to site nasogastric or nasoenteric feeding tubes using standard intubation techniques. We describe an endoscopic method of tube placement applicable not only for positioning nasogastric feeding tubes in patients with coexisting oesophageal pathology, but also for placement of nasoenteric feeding tubes when disordered gastric emptying is present.
Oral rehydration in acute infantile diarrhoea with a glucose-polymer electrolyte solution.
Seven infants with mild acute diarrhoeal dehydration were rehydrated with an oral sugar-electrolyte solution containing a glucose polymer mixture. Six of them were rehydrated successfully. The high sodium content of the solution (90 mmol/l) was based on the WHO/UNICEF recommended glucose-electrolyte solution and was implicated as the cause of increases in serum sodium in 4 infants, one of whom developed serious hypernatraemia associated with glucose-positive stools. A solution with a lower sodium and glucose-polymer content may be of nutritional benefit in the oral rehydration of acute infantile diarrhoea.
Characterization and nutritional significance of peptide transport in man.
An in vivo intestinal perfusion technique has been used to investigate the characteristics of di- and tripeptides absorption in man. The results suggest that the model peptides studied were absorbed by a transport system separate to those responsible for mediating absorption of free amino acids. Two modes of intestinal uptake have been identified, namely transport of unhydrolysed peptides and transport of free amino acid residues liberated from the peptides by the action of brush border peptidases. A consistent finding was that amino acid residues were absorbed more rapidly from di- and tripeptides than from free amino acids. When amino acid uptake from four partial enzymic hydrolysates of protein was investigated, the 'kinetic advantage' conferred by peptides on amino acid uptake was found to be a generalized and concentration-dependent phenomenon. As later test meal studies showed that orally administered peptide mixtures were assimilated at least as rapidly as free amino acid mixtures, serious consideration could be given to using the less hypertonic and more palatable oligopeptide-based nitrogen sources in chemically defined elemental diets.
A prospective reappraisal of emergency endoscopy in patients with portal hypertension.
In a prospective study of emergency endoscopy in patients with portal hypertension and oesophageal varices referred to King's College Hospital with acute upper gastrointestinal bleeding, initial endoscopic examination on 90 separate consecutive hospital admissions carried out within 24 h of clinical haemorrhage showed active variceal bleeding in only 21 (23.3%) cases. Coexisting upper gastrointestinal lesions were present in 38.8% of examinations, but active bleeding from these sites was seen in only five cases (5.6%). Of the 64 cases in which no active bleeding was seen at initial endoscopy, 39 (60.9%) rebled during that admission, and repeat endoscopy in 27 of these, carried out within 1 h of this episode, revealed active variceal haemorrhage in 20 (74.1%) cases. These results indicate that variceal haemorrhage is intermittent, and, although bleeding may often stop spontaneously, a high proportion of patients subsequently rebleed, and this is invariably from varices rather than from coexisting upper gastrointestinal lesions. In addition, these findings confirm the importance of emergency endoscopy in making the correct decision about acute management.
Disorders of nitrogen absorption.
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Malnutrition in liver disease and its relationship to hepatic encephalopathy.
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Prospective controlled trial of injection sclerotherapy in patient with cirrhosis and recent variceal haemorrhage.
64 patients with cirrhosis and recent variceal haemorrhage were studied in a prospective randomised trial of injection sclerotherapy by means of a flexible oesophageal sheath. 12 (33%) of the 36 patients in the sclerotherapy group, suffered further bleeds from varices compared with 19 (68%) of the 28 patients receiving standard medical treatment. The risk of bleeding per patient-month of follow up decreased more than threefold with sclerotherapy and the number of patients rebleeding after 2, 6, and 12 months was significantly reduced (p < 0.05). 1-year survival without further bleeding improved significantly with sclerotherapy (46% compared with 6%, p < 0.02), although the difference in overall survival assessed by cumulative life-table analysis was not statistically significant. The main complication of the technique was the development of oesophageal ulcers in some patients.
Indications for pump-assisted enteral feeding.
Of 80 patients fed enterally over nine months, 10 had serious gastrointestinal complications from gravity-controlled continuous enteral feeding. Use of an infusion pump controlled diarrhoea in patients with gastrointestinal disorders, but was less successful in patients with poor gastric emptying or impaired swallowing reflexes. Thus a pump is not indicated for routine use but, in carefully selected patients, it can obviate the necessity for parenteral nutrition.