Clinical efficacy and design changes of "fine bore" nasogastric feeding tubes: a seven-year experience involving 809 intubations in 403 patients

We report here our clinical experiences of "fine bore" nasogastric feeding tubes. Data have been collated over a 7-year period (1978-1985). A total of 403 patients were intubated on 809 occasions. In the first retrospective study, the clinical use of 491 unweighted tubes was compared with that of fifty 3.5-g weighted tubes. No advantage was found in the use of the weighted tubes. In the second prospective controlled clinical trial, these results were confirmed. Forty-six patients were intubated on 76 occasions with an 85-cm open-ended, unweighted nasogastric feeding tube (Prima, Portex UK), and 57 patients were intubated on 79 occasions with a 91-cm 3.0-g weighted tube (Entriflex, Biosearch, Raritan, NJ). Mean duration of placement was similar in each case, and 62% of both types of tubes were inadvertently removed. Without exception, all the tubes remained in the stomach throughout. Disappointed with the similar and overall performance of both types of tubes, we initiated a design program which resulted in the development of two new nasogastric tubes, one weighted and one unweighted. The tubes were manufactured with polyurethane, rather than polyvinylchloride (PVC), which permitted an increase in diameter of the internal lumen which, in turn, was coated with water-activated lubricant to ease removal of the introducer wire. A specially modeled outflow port was incorporated into the tips of both tubes. The performance of the two new polyurethane nasogastric feeding tubes was assessed under controlled trial conditions; as a reference, a widely used PVC unweighted open-ended tube was used.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inexpensive, safe and simple nasoenteral intubation--an alternative for the cost conscious

The efficacy and safety of nasoenteral feedings via small bore, flexible tubes have been extensively studied and reported. Most of the tubes currently used have similar characteristics including a high price ($7.00-$17.30 per tube). Our study using inexpensive ($0.55 each), polyvinyl pediatric feeding tubes and reusable guide wires in 21 patients shows that a weighted tip is not necessary for the passage of tubes into the duodenum (19/27 tubes passed) and that with proper nursing care and patient cooperation, the tubes can remain in place and patent for periods up to 71 days. The cost savings using the ubiquitous pediatric feeding tube and a reusable guide wire are significant (between $6.25 and $16.55 per tube used) and make this a more cost conscious alternative.     

A new nasal bridle for securing nasoenteral feeding tubes

A newly designed nasal bridle and rationale for its clinical use are described. Previous nasal bridles have been shown to reduce the 40 to 60% incidence of dislodgement of nasoenteral feeding tubes. Nasal bridles, however, are still not routinely used in nasoenteral feeding of patients who dislodge their feeding tubes. Instead, percutaneous gastrostomies and parenteral nutrition are increasingly being used in these patients who may otherwise be fed adequately with a secured nasoenteral tube. The newly designed nasal bridle described herein has the advantages of easy and rapid placement. Use of this bridle can promote safer and more effective enteral feeding while avoiding the complications and cost of parenteral nutritional and gastrostomies.     

Enteral access for nutrition in the intensive care unit

PURPOSE OF REVIEW: Enteral nutrition is the preferred route for nutrition support in the intensive care unit setting. This is usually delivered through nasoenteric feeding tubes in patients with an otherwise functional gastrointestinal tract. Placement of nasoenteric feeding tubes, however, may be difficult in this setting. Nasoenteric feeding tubes may be placed by multiple methods, each with their particular advantages and disadvantages. This review summarizes the recent literature on different methods of nasoenteric feeding tube placement with emphasis on critically ill patients. RECENT FINDINGS: Bedside assisted methods using electromyogram, electrocardiogram, and magnetic fields to provide immediate positional feedback to help guide tube advancement appear promising. Bedside methods using specific protocols, modified feeding tubes, prokinetics or magnetic assistance were also successfully reported. None of these methods has been prospectively compared with more commonly practiced methods in large studies. Endoscopic nasoenteric tube placement methods including transnasal approaches using ultra-thin endoscopes have been recently described and appear to be equivalent to fluoroscopic placement. All these recently reported techniques, however, may require more specialized equipment or training than is currently widely available. SUMMARY: Feeding tubes can be placed using bedside, fluoroscopic, and endoscopic means. Novel bedside methods have been recently described using immediate positional feedback or new assistive methods. Endoscopic techniques have similar success rates to fluoroscopic techniques and provide data on upper gastrointestinal abnormalities. There is no clear universal standard method. When feeding tube placement is required the technique used depends on local institutional resources and expertise.     

Improved design of nasogastric feeding tubes

Disappointed with the overall performance of weighted and unweighted nasogastric feeding tubes, a design programme was initiated which resulted in the development of two new nasogastric tubes, one weighted and one unweighted. The tubes were manufactured with polyurethane rather than polyvinylchloride (PVC) which permitted an increase in diameter of the internal lumen which in turn was coated with water activated lubricant to ease removal of the introducer wire. A specially modelled outflow port was incorporated into the tips of both tubes. The performance of the two new polyurethane nasogastric feeding tubes was assessed under controlled trial condition using as a reference a widely used PVC unweighted open ended tube. While intubation times were similar in patients without concurrent endotracheal intubation, it took a significantly shorter time to intubate patients with concurrent endotracheal intubation with the new weighted tube. Following tube intubation, it was possible to aspirate gastric contents significantly more often through the new polyurethane tubes (p < 0.001) than through the PVC tube, and the unweighted polyurethane tube stayed in situ longer (p < 0.05) than the PVC tube. The newly designed polyurethane nasogastric feeding tubes are the first tubes that have been shown to have advantages over the simpler type of open ended, unweighted PVC nasogastric feeding tubes.     

Lung perforation by nasogastric feeding tubes

Endotracheal misdirection of narrow bore nasogastric feeding tubes resulted in perforation of the lung, pneumothorax and hydrothorax in two intensive care patients. Both were intubated with cuffed endotracheal low pressure tubes, one patient was on respirator therapy with neuromuscular relaxation. Feeding tubes were inserted by experienced personnel with the assistance of a steel stylet without difficulties. Aspiration of fluid was misinterpreted as proof of correct positioning, the liquid being however pleural effusion and not gastric juice. Similarly auscultation of gurgling sounds in the upper epigastrium was not a reliable sign of intragastric position. Insertion of nasoenteric feeding tubes may be complicated by perforation of the upper gastrointestinal tract and lung in poorly responsive patients with cuffed endotracheal devices during neuromuscular blockage. In these patients a laryngoscope and forceps should be used to ensure free passage of the tube into the oesophagus. R?ntgenographic confirmation of correct positioning of the tube immediately after insertion is mandatory.     

Percutaneous needle pharyngostomy

Pharyngostomy is a technique of proven usefulness in patients requiring extra oral enteric access. Techniques to perform this have required an operating room, general anesthesia, and the associated risks. We have developed a technique for needle pharyngostomy that can be performed at the bedside of an awake patient. We utilize a central venous catheter tray and a small bore feeding tube to do this procedure. We have performed this on 17 patients without a procedural complication. This form of enteric access has allowed total nutritional support for up to 2 yr. Two late infections at the pharyngostomy site have occurred; both were easily controlled with oral antibiotics. This technique is recommended for patients who repeatedly pull out feeding tubes or are planning home enteral nutrition.     

Comparison of Gravity Flow Rates Between ENFit and Legacy Feeding Tubes

Background: Misconnections between enteral supplies and other access devices have led to significant morbidity and mortality. To reduce misconnections, a standard small‐bore connector has been developed (International Organization for Standards 80369‐8; ENFit). The full impact of transition to this connector is not known, however. Method: Working with major manufacturers and Food and Drug Administration, we obtained ENFit and comparative legacy tubes of variable sizes (low‐profile, 14F, 18F, 20F, and 24F balloon gastrostomies). Gravity enteral feeding was simulated with an empty bolus syringe attached to the feeding tube to be tested. The tube was clamped and filled to the 60‐mL mark with liquid (water, Jevity 1 Cal, Isosource HN, Isosource 1.5 Cal, Two Cal HN, and Nourish). The clamp was released, and time for formula to leave the syringe was recorded. Results: There was no difference in flow rate between the aggregate legacy and ENFit tubes for the low‐profile, 18F, and 20F sizes. The ENFit 14F tubes had a lower flow rate vs the legacy tubes, largely due to the low flow rates seen with the 1 ENFit tube. Similarly, 24F ENFit tubes with some formulas yielded lower flow rates as opposed to legacy. Conclusion: Overall, for the low‐profile, 18F, and 20F sizes, the ENFit tubes had similar flow rates when compared with the legacy tubes. For the 14F and 24F sizes, the flow rate of ENFit tubes was significantly lower, which could result in longer EN delivery for patients who are using these tubes to provide gravity feeding.     

Flow and aspiration of artificial feeds through nasogastric tubes

The physical characteristics of 12 nasogastric tubes (Clinifeed, Portex prima, Vygon 6 and 9, Dobbhoff, Nutriflex and 6 Ryles tubes) and 13 feeds (4 Clinifeed Preparations, Nutranel, Nutrauxil, Express, Triosorbon, Fortison, Enteral 400, Elemental 028, Complan and Complan + Caloreen have been assessed under laboratory conditions. The accuracy of the stated internal diameter of the tubes tested varied from 88-119%. The rate of flow was inversely related to the length of the feeding tube and was greatly affected by diameter (an increase from 1 to 2 mm increased flow 10-fold); and was virtually unaffected by the side holes at the end of the tube. Giving sets provide only a small resistance to flow. The viscosities of liquid feeds did not correlate with their osmolarities. The values ranged from 1.9-28 centipois (cps) at 24 degrees C and universally decreased to 1.4-19 cps at 37 degrees C. All enteral feeds except Clinifeed 500, flow satisfactorily through fine bore tubes under a low head of pressure. Undiluted Clinifeed 500 (a high protein feed) requires pumping. Feeds containing casein (e.g. Complan, Nutrauxil, Fortison, Triosorbon) curdle in the presence of acid which hinders aspiration through even widebore tubes. Foods containing whey protein (Express, Enteral 400) or no protein (Elemental 028) do not coagulate with change of pH. Batch to batch variations in liquid feeds are usually small but with one preparation were sufficiently large to cause problems in delivery. The results of these studies provide further data on which to base the choice of liquid feed and giving tubes in clinical practice.     

Verification of an electromagnetic placement device compared with abdominal radiograph to predict accuracy of feeding tube placement

Background: Use of an electromagnetic placement device (EMPD) facilitates placement of feeding tubes at the bedside. Standard practice for verification of feeding tube placement is via radiographic confirmation. The purpose of this research study was to assess the accuracy of placement of small‐bore feeding tubes (SBFTs) as determined by EMPD interpretation compared with that of abdominal radiograph verification by a radiologist. Methods: This multicenter prospective study enrolled patients requiring bedside feeding tube placement. SBFTs were placed by an experienced investigator using the EMPD. Two abdominal radiographs were then obtained: one after initial SBFT placement and an additional radiograph after injection of contrast. Documentation of location based on clinician interpretation using the EMPD was then compared with radiologist interpretation. Results: The final sample size was 194 patients, including 18 pediatric patients. Patient age ranged from 12 days to 102 years. Median time for tube placement was 12 minutes. Of the 194 patients, only 1 patient had data showing discrepancies between the original EMPD verification and the final abdominal radiograph interpretation, providing a 99.5% agreement. No patient experienced complications during SBFT placement, and 15 patients had inadvertent airway placement that was avoided with the use of the EMPD. Conclusions: There was a high percentage of agreement between EMPD and radiologic interpretation after contrast injection. The EMPD aided in avoiding inadvertent airway placement, with no patient complications. This device can be used safely at the bedside to facilitate placement of feeding tubes, leading to the delivery of early enteral nutrition.     

Nasoenteric feeding tubes in critically ill patients (fluoroscopy versus blind)

Numerous complications have been encountered with small-bore nasoenteric feeding tubes, some potentially life threatening. Patients particularly at risk are those with anatomic abnormalities, debilitation, or neurologic impairment. Fluoroscopy has been reported to be a safe, efficacious modality for the placement of these tubes. Thirty critically ill patients were studied to assess caloric delivery, costs, and complications associated with both fluoroscopically and blindly placed feeding tubes. All patients had either a tracheostomy or an endotracheal tube. They were randomized to group A (fluoroscopy) or group B (blind). Caloric delivery was greater in group A patients on days 1 through 5, with statistically significant differences on days 1 through 4. The mean daily calories per patient over the study period was 1135 +/- 96 and 662 +/- 110 (mean +/- SEM) in groups A and B, respectively (P < 0.01). Costs were similar in both groups. The most frequent problems encountered were difficult insertion, tubes requiring replacement, and failure to intubate the duodenum. We conclude that critically ill patients intubated either endotracheally or with tracheostomy should have nasoenteric feeding tubes placed with the guidance of fluoroscopy.     

Pleural complications of nasoenteric feeding tubes

Pliable, small-bore, feeding tubes are inserted frequently in critically ill patients. The use of wire stylets to facilitate passage of these tubes has increased the chances of unrecognized tracheal intubations, particularly in obtunded patients. Five patients with depressed sensoria had inadvertent transbronchial insertions of feeding tubes into their pleural spaces over a 28-month period. The incidence of this complication among intensive care unit patients was 0.3%. Sequellae included pneumothoraces in four patients, pleural effusions in three patients, and pneumonia with a pulmonary abscess in one patient. The presence of cuffed endotracheal tubes did not prevent this complication in patients with depressed cough reflexes. Inexperience of feeding tube insertors may have contributed to pleural intubations in four of the patients. In patients with depressed sensoria, adequate confirmation of feeding tube location in the stomach or duodenum requires both chest and abdominal roentgenograms.     

Do weighted nasoenteric feeding tubes facilitate duodenal intubations?

A widely held assumption is that postpyloric intubations occur more often with weighted than with unweighted nasally inserted feeding tubes. This randomized, prospective study compared the frequency of duodenal intubations using weighted and unweighted nasoenteric feeding tubes. One hundred sixteen patients had either weighted (61 patients) or unweighted (55 patients) 10F silicone elastomer feeding tubes inserted nasally 85 cm. Tubes were placed with wire stylets. Tube positions were verified radiographically within 4 hr after insertions. Radiographs were repeated daily for 3 days or until duodenal intubation occurred. Successful duodenal intubations were achieved in 35 patients (57%) with weighted feeding tubes and in 37 patients (67%) with unweighted feeding tubes. This difference was not significant. Weighted nasoenteric feeding tubes offer no advantage over unweighted tubes in achieving duodenal intubations.     

Overnight nasogastric tube feeding

Overnight nasogastric tube feeding allows the patient freedom for normal daytime activities and exercise, essential components of rehabilitation. In order to avoid disturbed nights through frequent micturition we have kept the volume of feed to a minimum. Two types of feed have been used: 1. A supplementary isosmolar feed containing 1000 kCals in 1 litre. 2. A concentrated low volume (404 mosm/kg) feed supplying 1800 kCals including 60 g of nitrogen in 1 litre. Both were delivered via a fine bore tube (internal diameter 1 mm) by continuous infusion from a 1-1.5 litre reservoir using a rotary pump. Feed 1 was given to 64 undernourished elderly female patients (group 1) with fractured neck of femur, the tube being tolerated by 78%; 47 patients in this group were fed for more than 5 days. Feed 2 was given to 10 patients in hospital (group 2) and 8 patients at home (group 3). Few side effects were encountered, the hyperosmolar feed causing no diarrhoea, nausea or hyperglycaemia, emphasising the importance of osmoles per unit time rather than per unit volume. Voluntary oral intake was neither impaired nor increased during the period of tube feeding in group 1, in whom anorexia and thinness were longstanding. In group 2, with recent onset of anorexia and weight loss, tube feeding disinhibited appetite, resulting in a doubling of voluntary oral intake. Improvement in anthropometric and biochemical nutritional parameters was seen in all patients. Clinical improvements e.g. closure of fistulae were also observed. This paper describes the results of our trial of both these options in patients treated in hospital or at home.     

Inadvertent dislodgement of nasoenteral feeding tubes: incidence and prevention

The introduction of soft, small-bore nasoenteral feeding tubes has improved our ability to provide nutritional support to patients in a more comfortable, safe, and cost-effective manner. A retrospective study reveals, however, that 40% of patients receiving nasoenteral tube feeding experienced inadvertent dislodgement of their feeding tubes. All of the patients with dislodged feeding tubes were confused, disoriented, or obtunded periodically. Various means for preventing this problem are discussed. In view of both the considerable time and effort required to place nasoenteral feeding tubes properly and the potential complications due to inadvertent tubes dislodgement, it is recommended that nasoenteral feeding tubes be secured more effectively, particularly in confused or obtunded patients.     

Comparison of Syringe Compression Force Between ENFit and Legacy Feeding Tubes

Background: Since initial report in 1972, misconnections continue to be an issue, especially in hospitalized patients with multiple access devices. A new small‐bore connector standard (ENFit) has been proposed in order to minimize misconnections. Methods: Commercially available finalized ENFit tubes of a variety of sizes (14 French [Fr] size, 18Fr, 20Fr, 24Fr, and low‐profile) were obtained for current testing. Variety of commercially available formulas including blenderized tube feeding (BTF) products (Jevity 1 Cal, Abbott Nutrition, Abbott Park, IL; Nourish, Functional Formularies, Centerville, OH; Real Food Blends, Chesterton, IN) were tested. Results: Data from individual measurements were aggregated for ENFit and legacy tubes and revealed higher syringe compression force in legacy tubes compared with ENFit tubes for 20Fr size with Jevity formula. Our institution's BTF formula revealed that legacy tubes had lower syringe compression force than ENFit tubes for 14Fr tube size. Remaining measurements revealed no significant difference. Model 1 of regression analysis revealed that only formula and tube size were significant with R² of 0.63. Model 2 evaluating the impact of tube size, blender, time of blending, and legacy vs ENFit revealed that tube size, blender used, and blending time were significant with legacy vs ENFit being nonsignificant (R² of 0.72). Conclusions: Overall, only a small number of tube sizes (14Fr and 20Fr) with selected formulas revealed a significant difference between ENFit and Legacy tubes, with remaining studies finding no significant difference. Regression analysis revealed that variables such as formula, size of tube, blender used, and time of blending may have more impact on compression force.     

Dual‐Purpose Gastric Decompression and Enteral Feeding Tubes Rationale and Design of Novel Nasogastric and Nasogastrojejunal Tubes

Background: The importance of early postoperative nutrition in surgical patients and early institution of enteral nutrition in intensive care unit (ICU) patients have recently been highlighted. Unfortunately, institution of enteral feeding in both groups of patients often has to be postponed due to delayed gastric emptying and the need for gastric decompression. The design of current polyvinylchloride (PVC) gastric decompression tubes (Salem Sump [Covidien, Mansfield, MA] in the United States; Ryles [Penine Health Care Ltd, Derby, UK] in the United Kingdom and Europe) make them unsuitable for their subsequent use as either nasogastric enteral feeding tubes or for continued gastric decompression during postpyloric enteral feeding. To overcome these problems, we have designed a range of polyurethane (PU) dual‐purpose gastric decompression and enteral feeding tubes that include 2 nasogastric tubes (double lumen to replace Salem Sump; single lumen to replace Ryles). Two novel multilumen nasogastrojejunal tubes (triple lumen for the United States; double lumen for the United Kingdom and Europe) complete the range. By using PU, a given internal diameter (ID) and flow area can be incorporated into a lower outside diameter (OD) compared with that achieved with PVC. The ID and lumen and flow area of an 18Fr (OD 6.7 mm) PVC Salem Sump can be incorporated into a 14Fr (OD 4.7 mm) PU tube. The design of aspiration/infusion ports of current PVC and PU tubes invites occlusion by gastrointestinal mucosa and clogging by mucus and enteral feed. To overcome this, we have designed long, single, widened, smooth, and curved edge ports with no “dead space” to trap mucus or curdled diet. Involving up to 214° of the circumference, these ports have up to 11 times the flow areas of the aspiration ports of current PVC tubes. Conclusion: The proposed designs will lead to the development of dual‐purpose nasogastric and nasojejunal tubes that will significantly improve the clinical and nutrition care of postoperative and ICU patients.     

Prophylactic pancreatic enzymes to reduce feeding tube occlusions.

BACKGROUND: Small-bore, feeding tube occlusion is reported to be as high as 23% to 35%. Pancreatic enzyme solution has been used to dissolve internal clots in feeding tubes. This study examined the prophylactic use of pancreatic enzyme solution with continuous enteral feeding in critically ill patients. METHODS: This was a randomized, unblinded trial conducted in an intensive care unit at a tertiary care hospital. Feeding tubes were randomized to receive pancreatic enzyme solution every 4 hours or usual care. Pancreatic enzyme solution contained lipase 8,000 units, amylase 30,000 units, protease activity 30,000 units, sodium bicarbonate 300 mg, and 5 mL warm sterile water. RESULTS: Ninety-five feeding tubes were followed up in 101 patients. Ten feeding tubes (9.9%) developed primary occlusions. Analysis revealed 2/52 (4%) of the tubes in the enzyme arm had occlusions, whereas 8/49 (16%) of control tubes had occlusions (p = .04). Time to occlusion was significantly longer in the pancreatic enzyme arm (p = .02). CONCLUSIONS: The use of prophylactic pancreatic enzymes may reduce the incidence of feeding tube occlusions.     

Nasoenteral feeding tube insertion via fiberoptic endoscope for enteral hyperalimentation.

Total parenteral nutrition can maintain good nutritional status in selected patients. However, it can be accompanied by serious complications. It is generally agreed that enteral alimentation is more economical and safer. Gut should be used for nutritional replenishment whenever feasible. However, large-bore nasogastric feeding tubes can cause problems. Even fine-bore nasogastric tubes can cause aspiration pneumonia in obtunded and debilitated patients. In some patients it is clearly desirable to have the tip of the feeding tube in the distal duodenum or proximal jejunum. Previously described methods for placement of nasoenteral tubes may be unsatisfactory. We describe a safe, simple, and reliable method for endoscopic insertion of fine-bore nasoenteral feeding tube. We have used this method on 15 patients without complication.     

Spontaneous transpyloric passage and performance of 'fine bore' polyurethane feeding tubes: a controlled clinical trial

Certain groups of patients requiring enteral nutritional support are at increased risk of regurgitation and pulmonary aspiration of feed. Positioning of enteral feeding tubes distal to the pylorus has been advocated as a method of reducing such complications. Various techniques have been suggested to achieve postpyloric siting. Reports have indicated that lengthening the tube or altering the distal end tip configuration, by varying the tip profile or by the addition of a weight, may facilitate spontaneous transpyloric passage of the tube. This prospective controlled clinical study using three new polyurethane tubes demonstrates that the frequency of spontaneous transpyloric passage of the tube is not affected by tip profile or by the addition of a weight. Indeed, with all three tube designs only about one-third had passed spontaneously through the pylorus at 24 hr. Once through the pylorus the unweighted tube stayed in position significantly longer than the weighted tubes (p less than 0.005). We suggest that in those patients requiring post-pyloric feeding, endoscopic or fluoroscopic techniques should be used to position the tubes at the time of insertion, and that an unweighted tube should be used to prolong tube usage.