Acute Paralytic Ileus

Ileus is a condition in which there is neurogenic failure or loss of peristalsis in the intestine in the absence of any mechanical obstruction. It is commonly seen in hospital­ized patients as a result of  

1. intra-abdominal processes such as recent gastrointestinal or abdominal surgery or peritoneal irritation (peritonitis, pancreatitis, ruptured viscus, hemorrhage);
2. severe medical illness such as pneumonia, respiratory failure requiring intubation, sepsis or severe infections, uremia, diabetic ketoacidosis, and electrolyte abnormalities (hypokalemia, hypercalcemia, hypomagnesemia, hypophosphatemia); and
3. medica­tions that affect intestinal motility (opioids, anticholiner­gics, phenothiazines). Following surgery, small intestinal motility usually normalizes first (often within hours), fol­lowed by the stomach (24–48 hours), and the colon (48–72 hours). Postoperative ileus is reduced by the use of patient-controlled or epidural analgesia and avoidance of intrave­nous opioids as well as early ambulation, gum chewing, and initiation of a clear liquid diet.
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The intestines process your food along this journey through a series of wave-like movements called peristalsis. Paralytic ileus is the paralysis of these movements. It means that the muscles or nerve signals that trigger peristalsis have stopped working, and the food in your intestines isn’t moving. Accumulating stagnant food, gas and fluids in your intestines may cause you symptoms of bloating and abdominal distension, constipation and nausea. This is an acute condition, which means it’s temporary and reversible, as long as the underlying cause has been addressed.

Symptoms and Signs of Ileus

Symptoms and signs of ileus include abdominal distention, nausea, vomiting, and vague discomfort. Pain rarely has the classic colicky pattern present in mechanical bowel obstruction. There may be constipation or passage of slight amounts of watery stool. Auscultation reveals a silent abdomen or minimal peristalsis. The abdomen is not tender unless the underlying cause is inflammatory.

Diagnosis

The laboratory abnormalities are attributable to the under­lying condition. Serum electrolytes (sodium, potassium), magnesium, phosphorus, and calcium, should be obtained to exclude abnormalities as contributing factors.

Plain film radiography of the abdomen demonstrates dis­tended gas-filled loops of the small and large intestine. Air-fluid levels may be seen. Under some circumstances, it may be difficult to distinguish ileus from partial small bowel obstruction. A CT scan may be useful in such instances to exclude mechanical obstruction, especially in postoperative patients.

Ileus must be distinguished from mechanical obstruction of the small bowel or proximal colon. Pain from small bowel mechanical obstruction is usually intermittent, cramping, and associated initially with profuse vomiting. Acute gastroenteritis, acute appendicitis, and acute pancre­atitis may all present with ileus.

Treatment

The primary medical or surgical illness that has precipi­tated adynamic ileus should be treated. Most cases of ileus respond to restriction of oral intake with gradual liberaliza­tion of diet as bowel function returns. Severe or prolonged ileus requires nasogastric suction and parenteral adminis­tration of fluids and electrolytes.

Alvimopan is a peripher­ally acting mu-opioid receptor antagonist with limited absorption or systemic activity that reverses opioid-induced inhibition of intestinal motility. In five random­ized controlled trials in postoperative patients, it reduced the time to first flatus, bowel movement, solid meal, and hospital discharge compared with placebo.

Alvimo­pan, 12 mg orally twice daily (available only through a restricted program for short-term use—no more than 15 doses), may be considered in patients undergoing par­tial large or small bowel resection when postoperative opioid therapy is anticipated.