Nutrition is important in childhood, as a child has a lower energy reserve and a higher demand for calories due to its growth. However, if a child protracts from an illness, this could result in an onset of malnutrition. Results of several studies have shown that acute and chronic malnutrition are poor prognostic factors in critically ill children, and thus, adequate nutrition can only improve their prognosis. Infants and children are susceptible to the profound metabolic effects of critical illness. In addition, preexisting malnutrition has adverse consequences during the intensive care unit stay. Early enteral and parental feeding can improve nutrition deficits.
Enteral nutrition provides better delivery of nutrients, resulting in their improved metabolism and greater weight gain, compared with the results of parental nutrition. It is associated with fewer complications, is economical and is more easily controlled than parental nutrition. However, since the critically ill child has diminished gastric motility thus, oral feeding is usually poorly tolerated. This can result in abdominal distension with abundant gastric residual or vomiting accompanied by pulmonary aspiration. Intraluminal nutrients help to maintain the integrity of the gut mucosal barrier that limits the translocation of bacteria and endotoxin into the bloodstream. Loss of mucosal barrier function is a potential risk factor for the development of sepsis and multiple-organ failure.
The use of enteral feedings has been well established since the mid-20th century (Abbott, 1940). Since this time, the benefits of enteral feedings have been clearly reported in the literature (Corney, 2003). The advantages of initiating enteral feedings are many, and it is therefore preferred over parenteral nutrition. Enteral feeding has been proven to decrease the incidence of sepsis and pneumonia (Kudsk, 1992), maintain the mucosal integrity of the gut (Saito, 1987) and reduce impairment of immune functions during illness (Hernoon, 1989). From a financial perspective, enteral nutrition is also more cost-effective than parenteral nutrition. When initiating enteral feedings, two options are available: gastric or transpyloric feedings. During critical illness, gastroparesis may develop. There is an earlier onset of small-bowel recovery of peristalsis compared with gastric peristalsis. This phenomenon may place the critically ill patient at an increased risk of aspiration if gastrically fed. The occurrence of aspiration varies, with reports up to 46% in gastric feedings compared with 6% with transpyloric feedings (Kiver, 1984). The faster recovery of small-bowel peristalsis combined with the protective contribution of the pyloric sphincter lends to the foundation that transpyloric feedings are a safer method of delivery in critically ill patients. Although the benefits of initiating transpyloric feedings are apparent, the task of placing the feeding tubes is difficult. Several methods for the placement of transpyloric feeding tubes in critically ill adults and children have been studied and described in the literature. These include a “blind” bedside insertion, the use of weighted vs unweighted feeding tubes (Lord, 1993), fluoroscopic placement, and the use of prokinetic agents such as metoclopramide or erythromycin (Paz, 1996). Other novel approaches recently described include gastric insufflation (Saladis, 1998; Spalding, 2000, DaSilva, 2002) magnetic-assisted placement,(Gabriel, 2004) and a combination of other techniques coupled with electrocardiographic guidance (Slagt, 2004).
The nutritional support achieved by critically ill children is determined by feeding tolerance and the ability to advance the rate of feeding delivery until the goal is achieved.
Results of several studies have demonstrated the effectiveness of transpyloric and nasojejunal feeding to be an alternative in critically ill children having a high risk of pulmonary aspiration. These methods of feeding have been successfully used in premature newborns and in infants in the recent past.
A review of the literature indicates that there are many methods for nasoenteral feeding tube insertion, including a blind technique, use of guidance by sonography, fluoroscopy, or external magnet, and endoscopic techniques.
The use of the nasojejunal route for enteral nutrition has been advocated the use of the nasogastric route because of the increased risk of gastroesophageal reflux and aspiration in many of the children in whom enteric feeding is indicated (Sue, 2006; Olivar, 1974). The nasojejunal feeding route is also preferred over the nasoduodenal route because of experimental evidence that jejuna perfusion diminishes the volume of gastric reflux more than is achieved with duodenal perfusion (Gustke, 1970). A variety of techniques have been advocated for the placement of nasoenteric tubes. Blind placement, which is commonly used initially, has a lower success rate and a higher complication rate than guided placement (Ramos, 1986; McCuey, 1988; Harris, 1989; Prago, 1986; Thurlow, 1986). In the study of Prager et al. (1986), blind insertion of weighted nasoenteric tubes was compared with fluoroscopically guided placement of such tubes in patients admitted to a critical care unit. The success rate for transpyloric placement of 13 blindly inserted tubes was only 15% compared with a 95% immediate success rate for 20 fluoroscopically placed tubes. Thurlow (1986) described a bedside technique for nasoenteric tube placement with the use of a weighted tube system. The immediate success rate for transpyloric placement was 87%, although the success rate for jejuna placement was only 17%. Despite these limitations, bedside placement is still encouraged as an initial approach to nasoenteric tube placement in patients who do not require urgent nasojejunal feeding.
Endoscopic placement, which may be useful in difficult cases, necessitates the administration of anaesthesia and has a lower success rate than fluoroscopic guidance for placement into the jejunum (Ott, 1991). Frederick et al. (1982) described a new, unweighted tube cord composed of polyvinylchloride that had a Teflon-coated guidewire. The authors placed the tube with fluoroscopic guidance into the duodenum or beyond in 93% of cases. One of the major advantages of this tube is the conspicuous absence of an elongated, weighted tip, which facilitates radiographic positioning because of better torque control. Although the cost of this tube is slightly higher than the cost of other tubes available, it is still preferred as the Frederick- Miller catheter for fluoroscopically guided placement because of its increased rigidity (versus polyurethane) and lack of a distal flexible weighted system.
Fluoroscopically guided nasojejunal tube placement is a successful procedure in both adults (Gutreires, 1991) and children (Haffer, 1992). The single most common factor in the failure of tube placement in reported experiments was usually in association with diaphragmatic hernia. Possible explanations for this association include a more vertical orientation of the stomach in many of these patients and the lack of fixation by the ligament. In addition, the lack of a smooth duodenal sweep in these patients alters catheter mechanics, resulting in the catheter coiling upon itself or within the stomach. Other general causes for placement failure include gastric distention, gastric outlet obstruction, and lack of physician experience. The estimated midline radiation dose of 0.32 cGy is not negligible when one considers that multiple tube placements were performed in many of these children.
Fluoroscopically guided nasojejunal tube placement is a safe procedure. There are no immediate complications observed. The most common complication related to blind insertion, cannulation of the trachea bronchial tree, is avoided by direct observation of the tube passing through the oesophagus. Late complications and associations described in children include small-bowel perforation, enterocutaneous fistula, intussusception, hypertrophic pyloric stenosis, sinusitis, and otitis media (Patrick, 1988; Latchow, 1989).
In summary, fluoroscopically guided nasojejunal tube placement is a safe, successful, and commonly used method for providing enteral nutrition in children. The radiation exposure is relatively low but not negligible. The presence of malrotation should alert the physician to potential difficulty in placing the tip of the tube in the proximal jejunum. In these patients, the need for nasojejunal tube feeding should be carefully weighed against the risk of radiation exposure. In difficult cases, an experienced physician should perform the procedure.
Another technique for bedside placement of nasoenteric feeding tubes is with the use of sonographic or magnetic guidance (Cheek, 1973). Using sonography, Haffer et al. (1992) successfully placed transpyloric feeding tubes in 84.6% of patients in whom attempted blind placement was not successful. The primary disadvantage to their technique was dependence on patient positioning, with the left side down being favoured, as well as the need for specialized equipment and expertise. Also, the majority of tubes placed with either sonographic or magnetic guidance are located in the first portion of the duodenum, and a decreased incidence of aspiration complications has been noted when feedings are delivered distal to the ligament of Treitz. Several studies have addressed the use of fluoroscopy for nasoenteral feeding tube placement and reported success rates of 91%.
One advantage of fluoroscopic guidance is that tube positioning is confirmed, and feeds can be initiated immediately. In addition, documented complications, including trachea bronchial misplacement and cardiac arrhythmias, are rare (0.4%) (More, 1989). Disadvantages to the use of fluoroscopy include the need for a C-arm fluoroscope unit or travel to the radiology department. Moving critically ill patients is often difficult and can be unsafe. In addition, the patient and staff are exposed to radiation during the actual procedure. Patient conditions associated with failure of this technique include large hiatal hernia, prior gastric or duodenal surgery, or presence of a neoplasm (Cliffton, 1989). Numerous studies have addressed the efficacy of utilizing an endoscope to place nasoenteral feeding tubes, and various modifications of technique have been reported. Hudspeth et al. described a technique in which the endoscope is used to visualize the pylorus (Wilmore, 1988). Under the direct endoscopic vision, the feeding tube is then guided through the pylorus. A second endoscopic technique referred to as the “pull-along” method involves attaching a suture to the feeding tube tip, which can be grasped with forceps and moved to the correct location. Stark et al. reported a 93% success rate with this technique; however, procedure time and tube tip location were not given (Caillie, 1975). This method can be tedious and often complicated by retraction of the feeding tube during endoscope withdrawal. Another variation, referred to as the “alongside-the-scope” technique, involves the use of a guidewire and addresses some of these issues. A feeding tube with a guidewire threaded through it is advanced with the endoscope into the fourth portion of the duodenum. The guidewire increases the stiffness of the feeding tube, which allows pressure applied to the proximal end of the tube to be transmitted to the distal end, thereby preventing the retrograde migration of the feeding tube during the withdrawal of the endoscope.
Both the nasojejunal and the transpyloric feeding modes are observed to be just as effective in critically ill infants. Enteral feeding through a tube placed transpylorically is a simple and effective method for providing nutritional support in critically ill children. It can be employed immediately after major surgery. However, there are contraindications such as intestinal obstruction, severe digestive haemorrhage, or intractable diarrhoea.
Most children hospitalized in the PICU have respiratory disease as their initial problem. The high frequency of infiltrates on baseline chest radiographs makes detection of aspiration by chest radiographic findings a difficult process. Also, chest radiographs cannot differentiate aspiration of gastric contents from aspiration of oral pharyngeal secretions. Several factors may contribute to gastroesophageal reflux and aspiration even when feeds are delivered transpylorically. The lower oesophagal sphincter is the primary physiologic barrier preventing gastroesophageal reflux. The presence of a feeding tube passing through the pharynx can lead to an increased frequency of transient relaxations of the lower oesophagal sphincter (Mitthal, 1992). A tube crossing the lower oesophagal sphincter may also interfere with sphincter function, predisposing the patient to gastroesophageal reflux. Some authors (Delegge, 1995) have suggested that feeding tube ports must be located in the third duodenal segment or beyond to prevent reflux and aspiration. However, the distal delivery of nutrients may itself increase the production of gastric secretions. In one study of a critically ill child, gastric output nearly doubled after the institution of jejunal feedings (Chendrasekkhar, 1996).
Transpyloric feeding allows enteral nutrition in critically ill children supported by mechanical ventilation, with no influence of sedative agents or vasoactive drugs. In some studies, hypochloremia was observed, probably due to a large amount of drainage by the gastric tube, which made gastric evacuation more difficult. Electrolytic alterations, if any, were immediately corrected by intravenous replacements.
However, there were problems associated with achieving the passage of the feeding tube through the pylorus. Although the size of the pyloric canal in small infants makes the placement of the feeding tube technically difficult, the transpyloric passage of the feeding tube is possible even in premature newborns. Transpyloric passage of the feeding tube usually is not associated with severe complications, although intestinal perforation, enterocutaneous fistulas, and hypertrophic pyloric stenosis have been described in premature newborns (Patrick, 1988).
Some authors have reported higher efficacy of the passage of the tube through the pylorus, using fluoroscopic placement, although radioscopic scanning is not possible at the bedside in most intensive care units. Other investigators have suggested the use of echography as a method of assessing the correct placement of the feeding tube because of its availability and the absence of radiation. Sometimes, endoscopic placement of the transpyloric tube is necessary (Latchaw, 1989).
Another problem observed in critically ill children receiving mechanical ventilation is the need for a transpyloric feeding tube for nutrition and a second tube for gas and evacuation of gastric residuals, both usually introduced through the same nostril. A double-lumen tube for this purpose is commercially available for use in adults but not for children, and this needs to be further explored.
It can be concluded that transpyloric feeding can be a successful method for achieving adequate nutritional support in critically ill children who cannot receive oral or gastric feeding. Its indication should have preference over parenteral nutrition. An important conclusion from the immense studies conducted is that despite the administration of drugs that have deleterious effects on gastrointestinal motility, transpyloric feeding could still be achieved.
The placement of transpyloric feeding tubes can be a challenging task in critically ill pediatric patients. Although various methods of achieving proper placement have been elucidated in the literature, many techniques are not technically feasible or easily accomplished in the critically ill or injured child in the PICU setting. Several methods have proven costly or require that the patient be transported to another area of the hospital. This is often a less than ideal situation for the critically ill child.
Empirical evidence suggests the nasogastric tube as a safe and effective method for short term feeding in children with a variety of chronic conditions that can be regularly used at home and in hospital. Health professionals need to review their practice in relation to nasogastric tube management in children and ensure their practice reflects the best available evidence.
It can also be concluded that endoscopic placement of nasojejunal tubes is a safe, quick, and reliable option for enteral nutrition in critically ill patients, especially children. The use of a nasopharyngeal bridling system significantly decreases the incidence of migration or accidental tube dislodgement and can be employed safely and effectively in children with ease and efficiency.
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