What are the two types of bowel obstruction?

Mechanical:caused by an actual physcial barrier.

Extrinsic (most common): ex; hernia, band or adhesion, extrinsic tumor, Intramural : ex; tumor in the wall, stricture due to chron's, radiation, trauma (often it's somekindof damage and then healing which forms a scar)

Intraluminal: ex; bezoar (anything that obstructs from the inside, like even hair, unripened persimmons), gallstone, intussesception (bowel telescoping)

Paralytic ileus: caused by a motility disorder, resulting in failure to propel intestinal contents

What's the difference between a simple and closed loop bowel obstruction?

Simple: single point of blockage

Closed loop: 2 points of blockage cause it's looped on itself. Volvulus is one example (where the intestine loops around itself)

What are the effects of a mechanical bowel obstruction?

- decreased absorption of intestinal contents proximal to the point of obstruction

- distension of bowel with secretion or transudation of fluids and electrolytes into the lumen

- loss of ECF volume and electrolyte imbalance (due to the fact that the particles that are just sitting there exert an osmotic effect, so they attract fluid into the lumen!)

- hypovolemia, dehydration

- paralytic ileus secondary to electrolye imbalance

- devascularization causing perforation

- bacterial contamination with sepsis

- peritonitis

How do we classify paralytic ileus?

- according to the cause and extent of involvement

Generally:

- abdominal

- reflex

- metabolic

- drugs

-intrinsic

Describe the abdominal causes of paralytic ileus

- Recent surgery, trauma, sepsis

- Remember that the sympathetic system comes into play, and whenever you do something that will activate the SNS, you inhibit peristalsis. Remember that the PSNS stimulates rest and digest (ie peristalsis!)

- This is not the scar thing, that's mechanical!

What are the "reflex" causes of paralytic illeus?

What are the metabolic causes of paralytic ileus?

- Electrolyte imbalance, it's actually fairly common, especially post-op hypokalemia.

- Uremia

- Endocrine disorders, like hypoparathyroidism. He says remember to have an index of suspicion!

What drugs can cause paralytic ileus?

What are the clinical features of a mechanical bowel obstruction? Signs and symptoms.

Symptoms:

- usually sudden onset

- pain is colicky at first, steady if it's a strangulation

- vomiting

- obstipation (failure to pass gas and stool)

Signs:

- distension depends on area of obstruction

- hyperactibe "tinkley" bowel sounds at first, then abdomen becomes silent when it's bad (they say with ileus, so that will happen eventually if it's not treated I think)

- dehydration

- tachicardia/hypotension

- peritonitis/ sepsis if there is a perforation

What are the signs and symptoms of paralytic ileus?

- usually no colic or significant pain

- abdominal distension (same as mechanical)

- vomiting (same as mechanical)

- bowel sounds absent from the get go.

If someone shows signs and symptoms of obstruction, what should you do?

- start with plain abdominal x-rays (do it supine and standing or sitting up)

- consider CT scan, and with that you can consider contrast studies (but bare in mind that you're putting excess fluid into a backed up pipe already.

A doc says: oh yeah I'm about to show you an x-ray of someone with a bowel obstruction.. what do you expect to see?

- for mechanical

- gas in intestine proximal to the point of mechanical obstruction

- little or no gas distal to the mechanical obstruction

- fluid levels

- edema between the loops.

*big one we saw was air fluid levels. Air will rise to the surface. Remember through that if the whole bowel is full of fluid and there's no air it may look quite normal on x-ray, so in that case that's when CTs would help

When we're talking about bowel obstruction we talk about the "transition zone", what is that?

What are some helpful bloodwork investigations that could be done for someone with a bowel obstruction?

- Urea

- Creatinine

- Electrolytes (Na and K)

- Hematology (Hb, Hct, WBC)

- Acid/Base (pH, CO2, HCO3)

*acid base is good if you're looking for ischemic intestine, in that case they may have a higher than normal lactate level.

How can you treat someone with a bowel obstruction?

Mechanical: establish the site/cause and do sx if necessary.

Paralytic ileus: establish and treat cause, could use endoscopic control to alleviate symptoms and prevent some complications, and use prokinetic drugs

*Thoughout all of this you want to control intestinal distension and correct fluid/electrolyte imbalances.