SMALL
BOWEL OBSTRUCTION
Intestinal
contents, fluid, and gas accumulate above the intesti-nal obstruction. The
abdominal distention and retention of fluid reduce the absorption of fluids and
stimulate more gastric secre-tion. With increasing distention, pressure within
the intestinal lumen increases, causing a decrease in venous and arteriolar cap-illary
pressure. This causes edema, congestion, necrosis, and even-tual rupture or
perforation of the intestinal wall, with resultant peritonitis.
Reflux
vomiting may be caused by abdominal distention. Vomiting results in a loss of
hydrogen ions and potassium from the stomach, leading to a reduction of
chlorides and potassium in the blood and to metabolic alkalosis. Dehydration
and acidosis develop from loss of water and sodium. With acute fluid losses,
hypovolemic shock may occur.
The initial symptom is usually crampy pain that is wavelike and colicky. The patient may pass blood and mucus, but no fecal matter and no flatus. Vomiting occurs. If the obstruction is com-plete, the peristaltic waves initially become extremely vigorous and eventually assume a reverse direction, with the intestinal contents propelled toward the mouth instead of toward the rectum.
If the obstruction
is in the ileum, fecal vomiting takes place. First, the patient vomits the
stomach contents, then the bile-stained con-tents of the duodenum and the
jejunum, and finally, with each paroxysm of pain, the darker, fecal-like
contents of the ileum. The unmistakable signs of dehydration become evident:
intense thirst, drowsiness, generalized malaise, aching, and a parched tongue
and mucous membranes. The abdomen becomes distended. The lower the obstruction
is in the GI tract, the more marked the abdominal distention. If the
obstruction continues uncorrected, hypovolemic shock occurs from dehydration
and loss of plasma volume.
Diagnosis
is based on the symptoms described previously and on x-ray findings. Abdominal
x-ray studies show abnormal quantities of gas, fluid, or both in the bowel.
Laboratory studies (ie, elec-trolyte studies and a complete blood cell count)
reveal a picture of dehydration, loss of plasma volume, and possible infection.
Decompression
of the bowel through a nasogastric or small bowel tube is successful in most
cases. When the bowel is completely obstructed, the possibility of
strangulation warrants sur-gical intervention. Before surgery, intravenous
therapy is necessary to replace the depleted water, sodium, chloride, and
potassium.
The
surgical treatment of intestinal obstruction depends largely on the cause of
the obstruction. In the most common causes of obstruction, such as hernia and
adhesions, the surgical procedure involves repairing the hernia or dividing the
adhesion to which the intestine is attached. In some instances, the portion of
affected bowel may be removed and an anastomosis per-formed. The complexity of
the surgical procedure for intestinal obstruction depends on the duration of
the obstruction and the condition of the intestine.
Nursing
management of the nonsurgical patient with a small bowel obstruction includes
maintaining the function of the na-sogastric tube, assessing and measuring the
nasogastric output, assessing for fluid and electrolyte imbalance, monitoring
nutri-tional status, and assessing improvement (eg, return of normal bowel
sounds, decreased abdominal distention, subjective im-provement in abdominal
pain and tenderness, passage of flatus or stool). The nurse reports
discrepancies in intake and output, worsening of pain or abdominal distention,
and increased naso-gastric output. If the patient’s condition does not improve,
the nurse prepares him or her for surgery. The exact nature of the surgery
depends on the cause of the obstruction. Nursing care of the patient after
surgical repair of a small bowel obstruction is similar to that for other
abdominal surgeries.
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