Safe, Consistent, and Effective Nutrition Support Therapy
Gastric vs Small Bowel Feeding
There is a large group of critically ill patients in whom impaired gastric emptying presents challenges to feeding; 50% of mechanically ventilated patients demonstrate delayed gastric emptying, and 80% of patients with increased intracranial pressure following head injury [60]. In one prospective RCT, Huang et al (2012) showed that severely ill patients (defined by an APACHE II score > 20) fed by the nasoduodenal route experienced significantly shortened hospital LOS, fewer complications, and improved nutrient delivery compared to similar patients fed by the nasogastric route. Less severely ill patients (APACHE II < 20) showed no differences between nasogastric and nasoduodenal feeding for the same outcomes [61]. A recent systematic review [17] pooled data from 14 trials of 1109 participants who received either gastric or small bowel feeding. Moderate quality evidence suggested that post-pyloric feeding was associated with lower rates of pneumonia compared with gastric feeding (RR 0.65, 95% CI, 0.51 to 0.84). Low-quality evidence showed an increase in the percentage of total nutrient delivered to the patient by post-pyloric feeding (mean difference 7.8%, 95% CI, 1.43 to 14.18). Overall, the authors found a 30% lower rate of pneumonia associated with post-pyloric feeding. There is insufficient evidence to show that other clinically important outcomes such as duration of mechanical ventilation, mortality, or LOS were affected by the site of feeding. The American Thoracic Society and ASPEN, as well as the Infectious Diseases Society of America, have published guidelines in support of small bowel feeding in the ICU setting due to its association with reduced incidence of health care–associated infections, specifically ventilator-associated pneumonia [62]. The experts who developed the SCCM/ASPEN and Canadian guidelines stress that critically ill patients at high risk for aspiration or feeding intolerance should be fed using small bowel access [12,21]. The reality in ICU clinical practice is that many centers will begin with gastric feeding, barring absolute contraindications, and carefully monitor the patient for signs of intolerance before moving the feeding tube tip into a post-pyloric location. This follows the general recommendation by experts saying in most critically ill patients, it is acceptable to initiate EN in the stomach [12,21]. Protocols that guide management of risk prevention and intolerance typically recommend head of bed elevation, prokinetic agents, and frequent abdominal assessments [63,64].
Once the decision is made to use a post-pyloric feeding tube for nutrition therapy, the next decision is how to safely place the tube, ensure the tip is in an acceptable small bowel location, and minimize delays in feeding. Challenges related to feeding tube insertion may preclude timely advancement to nutrition goals. Placement of feeding tubes into the post-pyloric position is often done at the bedside by trained nursing or medical staff without endoscopic or fluoroscopic guidance; however, the blind bedside approach is not without risks. Success rates of this approach vary greatly depending on the patient population and provider expertise. Placement using endoscopic or fluoroscopic guidance is a safe alternative but usually requires coordinating a transport to the radiologic suite, posing safety risks and possible feeding delays for the patient [65]. Bedside use of an electromagnetic placement device (EMPD), such as Cortrak, provides yet another alternative with reports in the literature of 98% success rates for initial placement in less than 20 minutes. In a multicenter prospective study by Powers et al (2011), only one of 194 patients enrolled had data showing a discrepancy between the original EMPD verification and the final radiograph interpretation, demonstrating a 99.5% agreement between the two readings [20]. Median placement time was 12 minutes and no patient experienced an adverse event related to tube insertion using this device. The ability to monitor the location of the feeding tube tip in real time provides a desirable safety feature for the clinician performing bedside insertions. Nurses should consider incorporating the EMPD into the unit feeding protocol, as this would reduce the time to initiation of feedings with early and accurate tube insertion. Ongoing staff education and experience with the procedure are necessary elements to achieve the high rates of success often reported in the literature [66,67]. Procedural complications from placement of nasoenteral feeding tubes by all methods can be as high as 10%, with complication rates of 1% to 3% for inadvertent placement of the feeding tube in the airway alone [65]. Radiographic confirmation of tube placement is advised prior to initiating feeding, thus eliminating any possibility of misplacement and administration of formula into the lungs.
