Page 535 - ACCCN's Critical Care Nursing

512 P R I N C I P L E S A N D P R A C T I C E O F C R I T I C A L C A R E

although consensus on what constitutes a high gastric is difficult, even for experienced clinicians. High gastric
residual and any recommendations for interventions residual volumes have been linked to the potential for
remain controversial. Ceasing feeds in response to gastric pulmonary aspiration, although this has not been shown
141
141
residual volume is questionable, particularly as a bal- in research. Oropharyngeal secretions can contribute to
anced enteral diet in itself has a prokinetic effect. 142 nosocomial pneumonia and subglottic aspiration has
improved outcomes. 169 Nursing strategies to improve
gastric emptying includes elevation of the head of the bed
Practice tip 30–45 degrees (unless otherwise contraindicated),
170
In determining feeding intolerance, a single high gastric resid- reducing the likelihood of gastro-oesophageal reflux,
ual volume in the absence of physical examination or radio- which is present in up to 30% of patients in the supine
graphic findings should not result in the cessation of enteral position.
feeding. Persisting with enteral feeding has demonstrated ben- Prokinetic agents can improve gastric emptying and
efits. It is thought that a balanced enteral diet, in itself, has a feeding tolerance, and avoid gastro-oesophageal reflux
prokinetic effect. 143 and pulmonary aspiration. Cisapride, erythromycin and
metoclopramide have all been used clinically to improve
Development of diarrhoea is another complication for gastrointestinal motility. A systematic review noted that,
enterally fed patients, and is a common reason why as a class of drugs, promotility agents have a beneficial
enteral feeding is often reduced or ceased. Diarrhoea may effect on gastrointestinal motility in the critically ill
171
contribute to fluid and electrolyte disorders, patient (and patient. These prokinetic agents do, however, have
nursing) distress, and a higher cost of patient care. 144 undesirable effects. Use of erythromycin is associated
Unfortunately, defining diarrhoea is problematic, as it is with the development of bacterial resistance, and meto-
a subjective assessment that relies on nursing interpreta- clopramide is associated with numerous systemic side
tion rather than on quantifiable assessment of stool effects. Erythromycin is more effective than metoclo-
weight. 145 There are various aetiologies for diarrhoea in pramide in treating gastric intolerance among patients
the enterally fed, critically ill patient, including: receiving enteral nutrition. 172 However, combination
therapy with erythromycin and metoclopramide is more
● antibiotic use 146 effective than erythromycin alone in improving the deliv-
● hypoalbuminaemia 144 ery of enteral nutrition. 173
● use of histamine-2 receptor antagonists 147
● contamination of enteral feeding solution. 148 Assessment of pulmonary aspiration
Probiotic administration may limit the development Despite preventive strategies, pulmonary aspiration may
of diarrhoea, 149 although its efficacy is yet to be still occur in some patients, and accurate assessment is
established. 150,151 essential. Common methods that can be performed easily
at the bedside to determine whether a patient has expe-
Enteral feeding solutions present an excellent medium rienced aspiration of gastric contents and/or enteral
for the growth of microorganisms, 152 and bacterial con- feeding formula follow:
tamination of enteral feeds is common. 153-155 Strategies to
limit bacterial contamination of enteral feeding solutions ● The dye method involves the addition of blue food
include: colouring to the enteral feeding formula, theoretically
making it possible to visualise gastric contents if
● meticulous preparation of feeding solutions and they have been inhaled into the tracheobronchial
equipment 156 tree. However, the use of blue dye is poorly stan-
● commercially prepared formula used in preference to dardised and has a low sensitivity in detecting micro-
decanted feeds 157-159 aspiration. 174 The use of methylene blue is not
● use of closed feeding systems 93,160,161 recommended because of associated side effects and
● limiting the time feeding solution is kept at high costs. 175 There have been case reports of blue
room temperature once opened and hang dye absorption describing discolouration of the skin,
times 93,148,157,162-168 urine, serum and organs, 176 and refractory hypoten-
● meticulous attention to hand washing and limiting sion and severe acidosis, suggesting poisoning by a
manipulation of the enteral nutrition bags and deliv- mitochondrial toxin. 177,178 These safety concerns,
ery system at the bedside 153,155 coupled with minimal benefits, have resulted in the
Despite hesitancy by nurses to persist with enteral feeding recommendation that the practice of using blue
in the presence of diarrhoea, there is no evidence to food colouring in enteral feeding solutions be
179
support the withholding of enteral feeding in critically ill abandoned.
patients unless there are significant disturbances in fluid ● Measurement of glucose in tracheobronchial secre-
and/or electrolyte balance. tions is another method to detect pulmonary aspira-
tion. 180 As these secretions normally contain <5 mg/
dL glucose, higher amounts of glucose may indicate
Prevention of pulmonary aspiration the aspiration of glucose-rich enteral feeding
68
An important complication of enteral feeding is the formula. However, differences in enteral feeding
development of pulmonary aspiration and nosocomial solutions affect the sensitivity of this method, with
pneumonia. Determining whether aspiration has occurred low glucose solutions being more difficult to detect.