Constipation

Constipation – Jacob Parnell

Background

  • Always consider if pt is at risk for obstruction (see SBO section)
  • Lactulose can cause severe cramping and bloating frequently
  • Can exchange PEG for lactulose in cirrhosis (but usually more bloating)
    • Titrate lactulose BID to QID until 3-4 BMs achieved in cirrhosis
  • Combination therapy usually most effective
  • In pts with renal dysfunction/CKD, avoid Fleet enemas (sodium phosphate load)

 

Evaluation

  • Typical causes: medications (opioids, antidepressants, iron, anticholinergics)
    • Poor diet (low-fiber), low fluid intake, reduced mobility, acute illness, electrolyte disturbances, IBS, GI disease (IBD, colon cancer)
  • Clinically diagnosis, no need for KUB/CT scans unless obstruction suspected
  • Consider BMP to evaluate electrolytes
  • Rectal exam can be used to exclude obstructing rectal mass or fecal impaction

 

Management

  • Stop any above offending meds as possible
  • Increase water intake
  • Escalating pathway for constipation:
    • Senna BID + PEG (can give several times a day) try bisacodyl suppository then finally can try enema—tap water enema or SMOG enema (saline, mineral oil, glycerine)

 

Laxatives

Mechanism

Examples

Effects

Bulking-agent

Psyllium seed (Metamucil)

Absorb water and fecal bulk

Osmotic Laxatives

Polyethylene glycol (PEG) (Miralax, Golytely), Lactulose Mag citrate

Poorly absorbed sugars or saline are hyperosmotic—pull fluid into GI tract

Stimulant Laxative

Senna, Bisacodyl (Dulcolax)

Stimulates release of electrolytes by the mucosa

Stool Softener

Docusate (Colace, Phillips)

 Minimal efficacy if any

Emollient

Mineral oil

Lubricates stool

Enema

Tap water, soap sud, lactulose (never use Fleet enema)

Helps stimulate stool release

Opioid antagonist

methylnaltrexone

Important role in narcotic-induced constipation and paralytic ileus

Acetylcholinesterase inhibitor

Neostigmine: indicated in Ogilvie’s syndrome if cecal diameter >12 cm.

Relative contraindications include recent MI, acidosis, asthma, bradycardia, PUD, and beta-blockers. Decompression with colonoscopy used for select cases of Ogilvie’s refractory to medical management.

 

Administer 2 mg via slow IV over 5 min (monitor for bradycardia hypotension, asystole, seizures)

 

 

Additional Information

  •  “The hand that writes for opioids is also the hand that writes for a bowel regimen”
    • Senna BID + PEG daily (up to TID)
    • If severe constipation already developed, do above plus try methylnaltrexone
  •  CF pts (at risk for distal intestinal obstructive syndrome or DIOS)
    • Not treated as true obstruction but rather like constipation
    • PEG (QID) or just order “golytely” prep as if for colonoscopy preparation