[left]Intestinal obstruction
Intestinal obstruction is an interruption in the normal flow of intestinal contents along the intestinal tract.
The block may occur in the small or large intestine, may be complete or incomplete, may be mechanical or paralytic, and may or may not compromise the vascular supply. Obstruction most frequently occurs in the very young and the very old.
Types and Causes
1. Mechanical: A physical block to passage of intestinal contents without disturbing blood supply of bowel. High small-bowel (jejunal) or low small-bowel (ileal) occurs four times more frequently than colonic obstruction.
· Extrinsic—adhesions from surgery, hernia, volvulus (loop of intestine that has twisted).
· Intrinsic—hematoma, tumor, intussusceptions (telescoping of intestinal wall into itself), stricture or stenosis.
· Intraluminal—foreign body, fecal or barium impaction, polyp
2- Paralytic (Adynamic, Neurogenic) Ileus
Peristalsis is ineffective (diminished motor activity perhaps because of toxic or traumatic disturbance of the autonomic nervous system).
There is no physical obstruction and no interrupted blood supply.
Disappears spontaneously after 2 to 3 days.
Causes include:
- Spinal cord injuries; vertebral fractures.
- Postoperatively after any abdominal surgery.
- Peritonitis, pneumonia
- Wound dehiscence (breakdown).
- Gastrointestinal tract surgery.
3- Strangulation :
Obstruction compromises blood supply, leading to gangrene of the intestinal wall. Caused by prolonged mechanical obstruction.
Altered Physiology
Results in increased peristalsis, distention by fluid and gas, and increased bacterial growth proximal to obstruction. The intestine empties distally.
Increased secretions into the intestine are associated with diminution in the bowel’s absorptive capacity.
The accumulation of gases, secretions, and oral intake above the obstruction causes increasing intraluminal pressure.
Venous pressure in the affected area increases, and circulatory stasis and edema result.
Bowel necrosis may occur because of anoxia and compression of the terminal branches of the mesenteric artery.
Bacteria and toxins pass across the intestinal membranes into the abdominal cavity, thereby leading to peritonitis.
“Closed-loop” obstruction is a condition in which the intestinal segment is occluded at both ends, preventing either the downward passage or the regurgitation of intestinal contents.
Clinical Manifestations
Fever, peritoneal irritation, increased white blood cell count, toxicity, and shock may develop with all types of intestinal obstruction.
Cramping pain wave like and colicky
Patient may pass blood and mucus but no fecal matter and no flatus
Vomiting if obstruction is complete
Dehydration develop patient have intense thirst , drowsiness, generalized malaise .
Abdomen distension.
Diagnostic Evaluation
X-rays—abdominal films show the presence and location of intestinal gas or fluid.
Barium enema shows a distended, air-filled colon or a closed loop of the sigmoid.
Laboratory results show decreased sodium, potassium, and chloride levels due to vomiting; elevated WBC counts with necrosis, strangulation, or peritonitis; increased serum amylase levels from irritation of the pancreas by the bowel loop.
Management:
Correction of fluid and electrolyte imbalances: Ringer’s lactate to correct interstitial fluid deficit. Dextrose/water to correct intracellular fluid deficit.
Long-tube decompression of intestine proximal to the blockage site; the tube can be passed more effectively with the patient lying on right side.
Treatment of shock and peritonitis.
Hyperalimentation may be necessary to correct protein deficiency from chronic obstruction, paralytic ileus, or infection.
Analgesics and sedatives, but not opiates because they inhibit GI motility.
Antibiotics for peritonitis.
Surgery consists of relieving obstruction through bowel resection. Options include:
- End to end anastomosis
- Double barrel ostomy if end to end anastomosis too risky
- Loop colostomy to divert fecal stream and decompress bowel, with bowel resection to be done as second procedure
Complications
· Dehydration due to loss of water, sodium, and chloride
· Peritonitis
· Shock due to loss of electrolytes and dehydration
· Death due to shock
Nursing Assessment
Describe the nature and location of the patient’s pain, the presence of distention, the absence of flatus or defecation in the nursing history.
Monitor and record bowel sounds in all four quadrants.
Conduct frequent checks of the patient’s level of responsiveness; decreasing responsiveness may offer a clue to an increasing electrolyte imbalance or impending shock.[/left]
موضوع: Intestinal obstruction 
17/11/2009, 02:31
