Gastrointestinal Tract
VBMC TRAUMA CARE SERVICES GUIDELINE
Gastrointestinal Tract
There is a widely held misconception that the gastrointestinal tract is quiescent following illness, injury, and/or surgery. The gut plays an active role in overall host defenses, gastrointestinal stress ulceration, and systemic inflammation.
The historical term attached to the clinical problem of post-operative gut dysfunction was “paralytic ileus”. This has been shortened in modern medical terminology to “ileus.” The traditional clinical practice is to withhold oral intake and maintain nasogastric decompression until there was clinical evidence indicating return of bowel function (passage of flatus, bowel movement, or audible bowel sounds). This practice is outdated and not consistent with what is currently known about bowel function in illness.
The stomach and small bowel function very well following illness, injury, and /or operative intervention unless there has been mesenteric ischemia or long-standing obstruction. The actual root cause of the clinical entity referred to as “ileus” is delayed return of colonic function. Although ingrained in our medical terminology, “ileus” is a misnomer and the proper term to use is colonic pseudo-obstruction.
There
are several clinical practices that either exacerbate or contribute to colonic
pseudo- obstruction. Chief among these are bed rest, narcotic administration
and fluid & electrolyte abnormalities. Depending on the clinical
circumstances, the clinician also needs to consider other contributing factors
such as fecal impaction, resolving peritonitis, intra- abdominal abscess,
pneumonia, wound infection, retroperitoneal hematoma, and pseudomembranous
colitis. Mesenteric ischemia and early mechanical bowel obstruction, although
rare, must also be considered in the differential diagnosis.
For most patients, early mobilization, judicious use of narcotics, as well as attention to fluid & electrolytes can mitigate or prevent pseudo-obstruction. Routine use of an effective bowel regimen and/or early enteral nutrition is also effective depending on the patient and clinical circumstances.
The main risk to the patient with pseudo-obstruction is colonic ischemia and/or perforation which are dependent upon the degree of colonic distention. Perforation/ischemia is much more likely when colonic/cecal diameter is > 11cm. Under these circumstances, more aggressive management is warranted. For most patients, the treatment of pseudo-obstruction is relatively straightforward. Bowel rest, hydration, and correction of electrolytes are essential. Narcotics should be reduced as much as possible. Depending on the clinical situation, other treatable contributing factors need to be rectified or excluded. Nasogastric tubes are completely unnecessary for the vast majority of patients because they are not effective in reducing colonic distention. NG tubes should be withheld unless the patient is vomiting and/or has evidence of gastric distention on X-ray. A combination of stool softeners and cathartics accompanied by a prokinetic agent Reglan (metaclopramide) are usually effective. Cathartics and prokinetic agents are more effective when given orally but other routes of administration may be necessary depending on the clinical situation. Rectal stimulation with a suppository and/or enema may also produce results. For refractory patients or those with significant colonic distension, a parasympathomimetic agent (neostigmine) can be administered IV with excellent results. Routine use of neostigmine is precluded by side effects such as bradyarrythmias, bronchorrea, and diaphoresis. Patients should be monitored during drug administration particularly if they have known cardiac disease. Decompressive colonoscopy which is both diagnostic and therapeutic may be required for patients with significant colonic distention not responsive to the above measures.
Enteral Nutrition
Not all patients require early enteral nutrition. Well-nourished patients who sustain mild to moderate injury or those undergoing elective operations tolerate up to seven days of fasting with little or no adverse consequences. However, patients with documented pre-injury or pre-operative malnutrition as well as those patients with complex critical illness/injury clearly benefit from early enteral nutrition. In fact, the evidence supporting early enteral nutritional support in the critically ill is clear and irrefutable. Infectious complications are significantly reduced in patients who receive early enteral nutrition. Early enteral nutrition also maintains gut integrity, reduces the risk of gastrointestinal stress ulceration, and increases the rate of wound healing.
Access routes
The main difficulty with early enteral nutrition is achieving and maintaining a reliable feeding access. Gastric feeding is well tolerated, and most patients can be fed in the stomach. Unfortunately, tolerance is an issue for some patients, monitoring may be difficult, and the aspiration risk is higher than that for post-pyloric tubes. As the patient improves clinically, aspiration risk declines and the need for post- pyloric access diminishes.
Three approaches are used to establish feeding access: nasoenteral feeding tube, surgical jejunostomy, and percutaneous endoscopic gastrostomy (PEG).
For the vast majority of patients, a
nasoenteral feeding tube is a safe, temporary access. These can be placed
blindly (discouraged), via Cortrak image guidance, via endoscopy, fluoroscopy,
or at the time of surgical intervention. Since these tubes frequently become dislodged,
they should be secured in place with a bridle. Nasoenteral feeding tubes are
not a reliable long-term access and should be replaced with a jejunostomy or
gastrostomy tube. When a patient has significant foregut pathology, a surgical
jejunostomy can be placed. This allows enteral feeding to proceed in the
absence of an intact/functioning foregut. The most frequently utilized long-term
feeding access is the PEG. This is a safe, effective way of delivering enteral
nutrition for most patients.
Assessing enteral feeding tolerance
Continuous
feeding is the only method used for post-pyloric nasoenteral and jejunostomy
feeding tubes. The small bowel will not tolerate bolus feedings. Continuous
feeding is preferred even for PEG feedings early but can be changed over to
bolus feedings over time. Feeding intolerance manifests clinically in a variety
of ways. The key to delivering effective enteral nutrition is to be aware of
the clinical manifestations of feeding intolerance and to realize that signs of
intolerance vary depending on the feeding access used. Tube feeding reflux,
high gastric residuals, vomiting, aspiration, abdominal distention, and
diarrhea are all signs of feeding intolerance.
Tube feeding reflux
In
patients with a post-pyloric nasoenteral tube and a nasogastric tube, the first
sign of intolerance can be tube feeding reflux in the nasogastric aspirate. The
first maneuver should be to confirm tube positions with a radiograph. NG tubes
can migrate distally and feeding tubes can be dislodged. Tubes should be
repositioned if necessary. Once tube position has been confirmed, then a
downward adjustment in rate and/or the addition of a prokinetic agent may be
required. If reflux is significant and accompanied by abdominal distention, the
best course of action is to hold tube feedings for 12-24 hours and reassess the
patient. Sudden abdominal distention and reflux in a patient previously
tolerating tube feeds is a very worrisome finding that warrants further
investigation.
High gastric residuals
In
patients receiving continuous feeding via a PEG elevated gastric residuals are
the first sign of intolerance. Residuals should be monitored every 4-6 hours
and should not exceed the total of the tube feeding over that time period. When
the residuals are elevated to > 500cc in a 6-hour monitoring period, should
be withheld and rechecked after one period of rest. A prokinetic agent can be
added with success in some patients. Again, elevated residuals and abdominal
distention in a patient that previously tolerated feeds should alert the
clinician to a change in clinical status that warrants investigation.
Occasionally, patients will be fed into the stomach using a small bore
nasoenteral feeding tube. Residuals cannot be checked via these tubes and no
attempt should be made to do so.
Vomiting/Aspiration
Vomiting
and/or aspiration may be the first sign of feeding intolerance. In the awake
patient, complaints of nausea will precede the event, so don’t ignore this
complaint. This manifestation is more likely in patients being fed in the
stomach via PEG or nasoenteral feeding tube. Remember that post-pyloric feeding
reduces but does not eliminate vomiting/aspiration risk. The most prudent
course of action is to hold feedings. Depending on the clinical suspicion for
aspiration, an evaluation by a physician is warranted. Vomiting will usually
dislodge a nasoenteral feeding tube, so replacement and/or verification of
position is warranted.
Abdominal distention
Frequently overlooked, abdominal distention and bloating are the earliest and most reliable signs of intolerance. All patients receiving enteral nutrition should be evaluated daily. Not all patients require an intervention, but this should be noted and brought to the attention of the physicians caring for the patient. Acute and/or significant distention may indicate mesenteric ischemia or colonic pseudo- obstruction.
Diarrhea
Diarrhea
is probably the most frequent complication of enteral nutrition. Oddly enough
tube feeding is usually not the cause. Sorbitol containing medications are
frequently to blame so a review of the medication record is warranted. If
indicated, clostridium difficile colitis should be excluded.
Higher tube feeding rates may produce diarrhea so a change in rate may be
warranted. Anti-diarrhea agents can be utilized if the problem persists.
Changes in formula can be made. If the volume of stool exceeds 500-1000cc per day,
then holding the feeds may be necessary.
Tube maintenance
Enteral
access tubes are expensive and vital to patient care. Every effort should be
made to maintain patency and protect against dislodgement.
Small bore feeding tubes
Standard
nursing guidelines for small bore feeding tubes should be rigorously followed
to prevent clogging. The most effective way to maintain patency is to flush
with tubes frequently with warm water and to avoid medication known to clog
these tubes. Whenever tube feedings are interrupted or medications are
administered, the tubes should be flushed with warm water.
PEG
These
tubes can and do become clogged and or dislodged. One of the most important
aspects of daily PEG care is to assess the tube site and determine tube depth.
Nurses should pay close attention to the insertion site for redness, swelling,
and/or tube feeding reflux. Following placement, PEG tubes are secured in place
using a silastic bolster. These bolsters are applied loosely to maintain the
PEG at the original depth of insertion which is charted in the endoscopic
procedure note. Each PEG tube has a centimeter marker on the side. The general
depth for most patients is between 3-6 centimeters. The depth at insertion
should be recorded on the nursing assessment. If the depth marker is more than
1cm less than or more than the insertion depth or there is tube feedings
refluxing through the insertion site, feedings should be held and the physician
notified immediately. Sustained tightening of the bolster, or sudden jerks on
the tube, can bury the mushroom-shaped ‘bumper’, which normally lies in the stomach,
into the wall of the stomach or abdominal wall. The result can be ‘feeding’ of
the tract rather than the gastric lumen, resulting in severe infection.
Remember, a sudden change in PEG feeding tolerance accompanied by abdominal
distention can indicate PEG tube migration or dislodgement.
Guideline for Prophylactic Antibiotic
for Percutaneous Endoscopic Gastrostomy
Translocation of endogenous microbial
flora can occur during endoscopic procedures such as percutaneous endoscopic
gastrostomy (PEG).1 While endoscopic related
bacteremia carries a low risk, with certain patient comorbidities and history
of previous procedures the risk increases.
Antibiotic prophylaxis can be useful
for prevention of infections related to some invasive procedures and in
specific clinical scenarios. Patients undergoing PEG tube placement
are at higher risk of bacteremia related to advanced age, compromised
nutritional status, immunosuppression, and comorbidities.1 Prophylactic
antibiotic therapy is recommended for these patients.1,2 The
therapy is recommended as pre-procedural and as a one-time dose.1,2 Cefazolin
that provides coverage for cutaneous organisms is adequate for this
therapy. In patients with methicillin-resistant Staphylococcus
aureus (MRSA) decontamination is recommended.
Recommended antibiotic regimen:
Cefazolin 2g IV for patients weighing less than 120 kg
Cefazolin 3g IV for patients weighing 120 kg or greater
If a history of a severe allergy to
penicillin is present, one of the following regimens may be used:
Clindamycin 900 mg IV or Vancomycin 15 mg/kg IV
PLUS
Gentamicin 5mg/kg IV or Aztreonam 2g IV or Levofloxacin
500 mg IV
1. Antibiotic
prophylaxis will be used in all patients receiving a PEG placement in the OR,
endoscopy suite, and ICUs.
2. Antibiotics
dosing should be weight-adjusted
3. Antibiotic
administration should occur within 60 minutes prior to incision, except for
vancomycin and fluoroquinolones which should be administered within 120 minutes
prior to incision.
4. The
antibiotic infusion should be complete before incision.
5. Post
procedure antibiotics are not warranted outside of a present infection or
contaminated procedure
Diarrhea
Not
all liquid stools constitute diarrhea. Diarrhea is defined as frequent loose
stools exceeding 1000cc per day and/or producing fluid/electrolyte
abnormalities. The clinical objective is to identify and remove treatable
causes of diarrhea. Medications are probably the most frequent cause of
diarrhea. Drugs that produce diarrhea such as prokinetic agents, oral
macrolides, cathartics, and sorbitol containing elixirs should be eliminated
when possible. Adjustments in tube feeding rate and/or formula change may be
required. Clostridium difficile colitis should be excluded or
diagnosed and treated. Diarrhea may accompany a high-grade fecal impaction.
Diarrhea may also be the only manifestation of intra- abdominal infection.
Surgical resection of the small or large bowel (ileocecal valve in particular)
may produce post-operative diarrhea. Diarrhea may follow resolution of
pseudo-obstruction or surgical relief of a mechanical small bowel obstruction.
In general, treatment is defined by the cause. Medications should be
changed/eliminated. Fecal impaction should be cleared. Except for C.
difficile colitis, symptomatic relief can be provided with
anti-diarrhea agents such as combinations of lomotil, Imodium, paregoric, and
narcotics.
Clostridium difficile (Pseudomembranous) Colitis
The
Gram-negative bacterium Clostridium difficile is part of the
normal colonic flora in roughly 20-25% of patients. The bacteria exist in small
numbers in balance with other colonic flora and do not cause any problems.
Pseudomembranous colitis develops because of an overgrowth of C.
difficile allowing for increased toxin production and mucosal damage.
The major mechanism is antibiotic administration that alters/reduces colonic
flora allowing room for increased growth of the drug-resistant C. difficile bacterium.
The disease can be produced by as little as one dose of antibiotics and most
often follows single dose antimicrobial administration for perioperative
prophylaxis. There is some data to suggest that mechanical bowel
preparation/cleansing may produce the disease as well. The most frequent
offending antimicrobials are cephalosporin (Rocephin), Clindamycin, ampicillin,
and fluroquinolones such as levaquin. The primary manifestation of the disease
is diarrhea which may occur up to 14 days after the last antibiotic
administration. Occasionally the patients will have abdominal pain and
distention. Rarely they will present with or have constitutional symptoms such
as fever and systemic toxicity that accompany the diarrhea and abdominal pain.
The diarrhea associated with the disease is quite distinct. The frequent
passage of small amounts of foul-smelling liquid stools should raise clinical
suspicion. The diagnosis is easily established by sending a stool specimen for
toxin assay. Cultures are of no value because the bacteria are normal resident
flora in many patients. First line therapy is metronidazole (Flagyl)
administered 10-14 days via the enteral route. Intravenous flagyl is effective
for patients who will not tolerate the oral route. Vancomycin given enterally
is reserved for patients who present with severe disease and/or fail on Flagyl.
Empiric therapy is appropriate after stool cultures have been obtained and can
be stopped if the toxin assay is negative. Endoscopy to identify pseudomembranes
is occasionally required to establish the diagnosis. Rarely, a patient will
develop toxic megacolon and require emergent surgical intervention.
Constipation
There is overlap between
constipation and colonic pseudo-obstruction. Abdominal pain, distension,
nausea, and vomiting accompanied by absence of a bowel movement for more than
several days are the most common symptoms. Unfortunately, these symptoms are
identical to colonic pseudo-obstruction so the diagnosis is difficult in the
hospitalized patient. Narcotics, bed rest, dietary changes, fluid &
electrolyte abnormalities, particularly dehydration all predispose the patient
to constipation. The key is prevention. Early mobilization of the patient and
adequate hydration is essential. Patients who require pain medications should
receive stool softeners as a routine. Once constipation develops attention
should be turned to correcting the problem. Fecal impaction should be excluded
by rectal exam. Remember that diarrhea may be a manifestation of fecal
impaction. Stool softeners alone are usually not enough. Unless the patient is
vomiting, oral cathartics should be tried initially. Oral Dulcolax tablets
and/or milk of magnesia (MOM) can be administered along with oral
metaclopramide (reglan) 10-20mg. Osmotic agents such as sorbitol are also
effective particularly if administered with dulcolax. These regimens can be
repeated. If the patient is vomiting or does not respond to oral therapy,
digital rectal stimulation with a dulcolax suppository with or without enemas
can be employed. Large volumes of laxatives such is Mirilax or citrate of
magnesia should be avoided in patients who already have significant bloating.
References:
1. American
Society of Gastrointestinal Endoscopy. Antibiotic prophylaxis for GI
endoscopy. Gastrointestinal Endoscopy. 2015 81(1):
81-89. http://dx.doi.org/10.16/j.gie.2014.08.008
2. Ban,
KA; Minei, JP; Laronga, C; Harbrecht, BG; Jensen, EH; et al. American College
of Surgeons and Surgical Infection Society: Surgical Site Infection Guidelines,
2016 update. Amer Coll Surgeons. 2016; 10: 59-73. http://dx.doi.org/10.1016/j.jamcollsurg.2016.10.029
3. Bratzler
DW; Dellinger EP; Olsen KM; et al. Clinical Practice Guidelines for
Antimicrobial Prophylaxis in Surgery. AM J Health Syst Pharm. 2013
70(3):195-283. DOI: 10.2146/ajhp120568