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)     

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.     

Clinical evaluation of a newly designed nasogastric enteral feeding tube

Concerned with reports in the literature of a rising incidence of enteral feeding tube clogging, we initiated a design programme in an attempt to improve the clinical efficacy of nasogastric and nasoenteric enteral feeding tubes. Tube design has been based on a remodelling of the outflow part of a polyurethane feeding tube previously developed in our unit. The tip of the newly designed 8F enteral feeding tube is shorter in length with a rounded end to minimize discomfort during intubation. The port itself incorporates a tapered outflow design with the side walls now extending below the mid-point of the internal flow lumen resulting in a 28% increase in port area compared to the equivalent and originally designed tube. The performance of the newly designed polyurethane feeding tube was assessed under controlled trial conditions using as references two widely used 8F polyurethane nasogastric feeding tubes whose design has been based on different principles (Flexiflo, weighted tip, open-ended with two side ports; Freka, occluded tip, two simple large side ports). Eighty-eight of 90 patients entered into the study were successfully intubated with no significant differences being noted in intubation times in the three groups. Significantly less discomfort occurred during intubation of patients with the Radius tube as compared to the Freka tube (P < 0.05). Although there were no clear differences between the Flexiflo and Freka tubes either in regard to the number of attempts required for intubation or aspiration or discomfort during intubation or ease of aspiration, fewer attempts at insertion and aspiration were needed and intubation and aspiration were easier for patients randomised to the Radius group than those to the Flexiflo and Freka groups (P < 0.05). We conclude that the clinical performance of the newly designed Radius enteral feeding tube compares favourably with that of the reference tubes. Only one of the new tubes (3.3%) blocked during the course of the study. High rates of non-elective extubation were observed in the three study groups (Radius 80.0%, Flexiflo 73.3%, Freka 73.3%). Design modifications are unlikely to influence non-elective nasogastric feeding tube extubation rates which remain a major clinical problem.     

Pneumothorax following attempted nasogastric intubation for nutritional support

Nasogastric intubation is a routine procedure, performed daily by both medical and nursing staff. It is a simple procedure, but not without complications which can be life threatening. We present an unusual, life threatening complication which occurred when nasogastric intubation using a no. 8 polyurethane tube with its metal stilet resulted in a pneumothorax after intubation of the endotracheal tree in the presence of a cuffed endotracheal tube. We emphasize that the presence of a cuffed endotracheal tube should not be considered a safeguard against pulmonary intubation during nasogastric placement of a feeding catheter.     

7 g weighted versus unweighted polyurethane nasoenteral tubes--spontaneous transpyloric passage and clinical performance: a controlled randomised trial

A proportion of patients requiring enteral nutrition is at increased risk of regurgitation or pulmonary aspiration of enteral diet as a result of gastric atony or paresis. The positioning of the distal end of an enteral feeding tube beyond the pylorus into duodenum or jejunum may reduce this risk. It has been postulated that by suitable lengthening of feeding tubes and by altering the distal end tip profile or by the addition of a weight, spontaneous passage of a tube through the pylorus after pernasal insertion may be achieved. In a recent controlled trial we were unable to demonstrate any advantage to a) modifying the tip profile or b) the addition of a 2.4 g weight. This prospective controlled clinical study examined the difference between an unweighted polyurethane tube which had performed optimally in the previous study and a new 7 g weighted tube similar in all other respects. In both cases less than 50% of tubes had passed spontaneously through the pylorus when assessed at 24 h, with no significant difference in performance (p = 0.38). When comparing overall length of time that each tube remained in situ, there was similarly no significant difference between the 7 g weighted and unweighted tubes (p = 0.277). We conclude that the addition of a 7 g weight to a suitably lengthened enteral feeding tube confers no advantage on either incidence of spontaneous transpyloric passage or in prolonging tube usage. If post-pyloric feeding is indicated for a patient, positioning by either fluoroscopic or endoscopic techniques should be undertaken.     

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.     

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.     

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.     

When Does Metoclopramide Facilitate Transpyloric Intubation?

Postpyloric feeding probably reduces the incidence of tracheobronchial aspiration and improves feeding tolerance. However, duodenal intubation is often unsuccessful in critically ill patients due to gastric atony. Metoclopramide improves gastric emptying. In a pilot study, 12 adult patients were administered 10 to 20 mg of intravenous metoclopramide after weighted nasal feeding tubes had failed to spontaneously pass distal to the pylorus. In no patient did metoclopramide induce transpyloric passage of the tube. A randomized prospective study involving 10 adult patients was conducted to examine the effect of preinsertion intravenous metoclopramide on transpyloric intubation. All patients had failed to achieve spontaneous duodenal intubation. Five patients received 20 mg of metoclopramide 10 min prior to nasal insertion of a weighed feeding tube. Five control patients received no premedication. Four metoclopramide patients achieved duodenal intubation immediately. In none of the control patients did transpyloric intubation occur (p = 0.048). Metoclopramide, administered after nasogastric intubation, is ineffective in promoting transpyloric advancement of feeding tubes. There is a significant increase in transpyloric intubation when metoclopramide is administered prior to tube insertion.     

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.     

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.     

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.     

Efficacy of metoclopramide as an adjunct to duodenal placement of small-bore feeding tubes: a randomized, placebo-controlled, double-blind study

We examined whether metoclopramide would improve the success rate of transpyloric intubation of a weighted Corpak feeding tube when fluoroscopic guidance is not used. Seventy patients were randomized in a prospective, double-blind fashion to receive either placebo (n = 35) or metoclopramide, 10 mg (n = 35) parenterally, administered immediately after the feeding tube was inserted. Tube location was determined independently by two observers who examined radiographs obtained after barium was instilled via the tube. There was no significant increase in the success rate of duodenal intubation in the total group following metoclopramide, 60%, compared to placebo, 49%. However, analysis of subgroups among the placebo-treated patients revealed that diabetes mellitus, but not other medical conditions, decreased the success rate for duodenal intubation, 20 vs 60% (p less than 0.05). Among diabetic patients, metoclopramide resulted in a significant increase in duodenal placement compared to placebo (p less than 0.05). We conclude that parenteral metoclopramide significantly increases the frequency of transpyloric intubation with small feeding tubes without fluoroscopic guidance in diabetic patients but not in nondiabetic patients.     

Do nasogastric feeding tubes cause gastro-oesophageal reflux in healthy subjects?

The potential relationship between nasogastric intubation and acid gastro-oesophageal reflux was investigated. Ten healthy volunteers underwent 24h oesophageal pH monitoring following intubation with (i) a pH monitor alone, (ii) a pH monitor plus a Ryles nasogastric tube and (iii) a pH monitor plus a fine-bore nasogastric feeding tube. Neither of the nasogastric intubations were associated with significant reflux.     

Nasopulmonary intubation with feeding tubes: case reports and review of the literature

Pulmonary aspiration of regurgitated feeding material is a recognized complication of enteral nutrition by feeding tube. Nasopulmonary intubation with feeding tubes has been reported infrequently. We present two patients with such complications. In one, nasopulmonary intubation resulted in a pneumothorax. In the other unrecognized misplacement resulted in pneumonia and hydrothorax. Similar cases in the literature are discussed. Common features of this complication are: (1) patients who are obtunded, debilitated, or without gag reflex; (2) previous successful insertion of a tube; (3) successful passage past endotracheal tubes and tracheostomies; and (4) positive auscultation of insufflated air over the left upper quadrant. Complete prevention of this complication probably is not possible, but health care personnel should be aware of this potential problem in the patient at risk.     

Clinical audit: optimal positioning of endotracheal tubes in neonates

BACKGROUND: The malposition of endotracheal tubes (ETTs) can be associated with endo-bronchial intubation or accidental extubation. A variety of methods have been reported for predicting insertional length (IL) including weight, nasal-tragus length (NTL) and sternal length (STL) measurements. In our unit no consistent predictor method was being used. AIM: To audit the proportion of endotracheal tubes that required a significant position change after oral intubation. Our standard set was that the endotracheal tube should be in a satisfactory position in > 80% of cases. If not met, practice would then be re-audited after a consistent predictor method had been implemented. METHODS: Data regarding changes in endotracheal tube position were collected. Significant position changes were defined as adjustments > 0.5 cm. RESULTS: Twenty two babies were included in the initial audit, and only 73% of endotracheal tubes had a satisfactory position. Thirty six babies were included in the re-audit and when the nasal-tragus length predictor was used, 94% of endotracheal tubes had a satisfactory position, meeting the standard. CONCLUSION: The nasal-tragus length predictor improved the accuracy of endotracheal tube positioning after oral intubation. It is a simple, fast, reproducible method and can be used in everyday practice to help avoid significant endotracheal tube malposition.     

Determination of a practical pH cutoff level for reliable confirmation of nasogastric tube placement

Background: Enteral feeding is a common method of nutrition support when oral intake is inadequate. Confirmation of correct nasogastric (NG) tube placement is essential. Risks of morbidity/mortality associated with misplacement in the lung are well documented. Studies indicate that pH ≤4 confirms gastric aspirate, but in pediatrics, a pH of gastric aspirate is often >4. The goal of this study was to determine a reliable and practical pH value to confirm NG tube placement, without increasing the risk of not identifying a misplaced NG tube. Methods: Pediatric inpatients older than 4 weeks receiving enteral nutrition (nasogastric or gastrostomy) were recruited over 9 months. Aspirate samples were pH tested at NG tube placement and before feedings. If pH >4, NG tube position was confirmed by chest radiograph or further investigations. In addition, intensive care unit (ICU) patients who required endotracheal suctioning were recruited, and endotracheal aspirate samples were pH tested. Results: A total of 4,330 gastric aspirate samples (96% nasogastric) were collected from 645 patients with a median (interquartile range [IQR]) age of 1.0 years (0.3–5.2 years). The mean (standard deviation [SD]) pH of these gastric samples was 3.6 (1.4) (range, 0–9). pH was >4 in 1,339 (30.9%) gastric aspirate samples, and of these, 244 were radiographed, which identified 10 misplaced tubes (1 with pH 5.5). A total of 65 endotracheal aspirate samples were collected from 19 ICU patients with a median (IQR) age of 0.6 years (0.4–5.2 years). The mean (SD) pH of these samples was 8.4 (0.8) (range, 6–9.5). Conclusion: Given that the lowest pH value of endotracheal aspirate sample was 6, and a misplaced NG tube was identified with pH 5.5, it is proposed that a gastric aspirate pH ≤5 is a safer, reliable, and practical cutoff in this population.     

Prospective study of nasogastric feeding via East Grinstead or Viomedex tubes compared with oral dietary supplementation in patients with cirrhosis

Forty-seven patients with alcoholic hepatitis and/or cirrhosis were randomised to receive nutritional supplementation by oral sip feeding or by nasogastric infusion administered via either an East Grinstead or a Viomedex nasoenteric tube. The three groups were well matched for severity and complications of liver disease. Patients fed by the nasogastric route attained their daily target dietary intake significantly more often than did those supplemented orally, but the consequent improvement in their nitrogen balance was not significant. There were no significant differences between nasogastric and sip feeding, or between the types of tube studied, in the frequency with which vomiting, diarrhoea or variceal bleeding occurred, but Viomedex tubes required reinsertion significantly less frequently than did the East Grinstead type.     

超滑涂层气管导管用于全麻下非困难气道气管插管的临床效果

目的:与普通气管导管相比,观察超滑涂层气管导管是否减轻全麻插管刺激及改善操作效果。方法:选取2016年7月~2017年1月全麻插管的患者60例,ASA分级Ⅰ~Ⅱ级,患者随机分为超滑气管导管组(观察组)和普通气管导管组(对照组)。记录插管时间和插管阻力评价;记录诱导前(T0)、插管前(T1)、插管即刻(T2)、插管后1min(T3)、3min(T4)、5min(T5)、术毕自主呼吸恢复(T6)SBP、DBP、MAP和HR;记录拔管后和术后24h出现咽痛的情况。结果:两组患者T2、T3、T6时对照组SBP、DBP和MAP明显高于观察组(P<0.01),T2、T3、T4时对照组HR明显高于观察组(P<0.01),观察组插管时间短于对照组(P<0.05),对照组术后咽痛发生高于观察组(P<0.05)。结论:超滑气管导管在非困难气道使用时有益于患者血流动力学平稳,缩短插管时间,有效降低术后咽痛的发生率,是一种安全有效的气管插管工具。     

Efficacy of erythromycin for postpyloric placement of feeding tubes in critically ill children: a randomized, double-blind, placebo controlled study

BACKGROUND: Erythromycin enhances gastric emptying and has been suggested to facilitate nasoenteric feeding tube placement in adults. Our primary objective was to evaluate the effect of erythromycin on the transpyloric passage of feeding tubes in critically ill children, and second, to evaluate the effect of erythromycin on the distal migration of duodenal feeding tubes. METHODS: Seventy-four children were randomly assigned to receive erythromycin lactobionate (10 mg/kg) IV or equal volume of saline placebo 60 minutes before passage of a flexible weighted tip feeding tube. Abdominal radiographs were obtained 4 hours later to assess tube placement. If the tube was proximal to the third part of the duodenum, two additional doses of erythromycin/placebo were administered 6 hours apart. Those receiving additional doses had repeat radiographs 14 to 18 hours after tube placement. RESULTS: The number of postpyloric feeding tubes was similar in the erythromycin and placebo treated groups 4 hours after tube insertion (23/37 vs 27/37, p = .5). Of those with prepyloric tubes at 4 hours, none in the erythromycin group and 3 in the placebo group had the tube migrate to the postpyloric position by 14 to 18 hours (p < .05). Of those with postpyloric tubes proximal to the third part of the duodenum at 4 hours, additional doses of erythromycin did not cause more tubes to advance further into the intestine than did placebo (p = .6). CONCLUSIONS: Erythromycin does not facilitate transpyloric passage of feeding tubes in critically ill children. The distal migration of duodenal tubes further into the small bowel is also not enhanced by erythromycin.