small bowel obstruction

small bowel obstruction

1. clinical manifestations

   • abdominal pain, vomiting, distention and constipation - the order and degree these appear vary by the location and the type of obstruction.  
   • complications
     • Complications - if blood flow is inadequate, bowel tissue becomes ischemic, then necrotic, and the bowel may perforate.  Bowel can become so distended that the blood flow completely stops, causes edema, cyanosis, and gangrene of a bowel segment - intestinal strangulation or intestinal infarction.  This can become necrotic and rupture, leading to infection, septic shock, and death Complications after bowel resection could be - bleeding in the intestines, intestines pushing through the incision, pus collecting in small bowel, frequent diarrhea, incision breaking open, scar tissue that forms an intestinal blockage and short bowel syndrome.  
   • causes
     • surgical adhesions, hernia, strictures from Crohn's disease, and intussusception after bariatric abdominal surgery.  Most common cause is colorectal cancer along with diverticular disease and sigmoid volvulus.  Other causes are peritonitis, inflammatory responses such as pancreatitis and appendicitis, electrolyte abnormalities, and thoracic and lumbar spinal fractures. 
   • types of obstructions
     • mechanical and nonmechanical  mechanical - physical obstruction of the intestinal lumen.   Pseudo-obstruction is a mechanical obstruction that no cause can be found.    nonmechanical - occurs with reduced or absent peristalis due to altered neuromuscular transmission - paralytic ileus is a nonmechanical obstruction and is the lack of intestinal peristalis and bowel sounds - most common form of nonmechanical
     • nursing interventions
       • Monitor pt closely for signs of dehydration and electrolyte imbalances.  Administer IV fluids.  Watch for signs and symptoms of fluid overload.  Monitor serum electrolyte levels.  Provide comfort measures and promote a restful environment.  If pt has NG tube - oral care is necessary and check NG tube every 4 hours for patency.  

2. pathophysiology

   • When an obstruction occurs, fluid, gas, and intestinal contents accumulate proximal to the obstruction.  Distention reduces fluid absorption and initially stimulates intestinal secretions.  Distal to the obstruction, the bowel empties and then collapses.  As distention increases in the proximal bowel, intraluminal bowel pressure rises.  The increased pressure leads to an increase in capillary permeability and extravastation of fluids and electrolytes into the peritoneal cavity.  Eventually the intestinal muscle becomes fatigued, and peristalsis stops.  

3. diagnostic studies

   • H&P, Imaging such as CT scans and x-rays to identify the presence and location.  Sigmoidoscopy and colonoscopy for direct visualization. Blood tests such as CBC and blood chemistries.  Elevated WBC may indicate strangulation or perforation.  Elevated hematocrit values may reflect hemoconcentration.  Decreased hemoglobin and hematocrit - beelding from a neoplasm or strangulation with necrosis.  Electrolytes, BUN and creatinine need to be monitored to assess for dehydration.  

4. potential nursing diagnosis

   • Acute pain related to abdominal distention and increased peristalsis.  Deficient fluid volume related to a decrease in intestinal fluid absorption, third space fluid shifts into the bowel lumen and peritoneal cavity, NG suction, and vomiting.