CONTENTS
- Basics
- Clinical presentation
- Differential diagnosis
- Evaluation
- Causes
- Approach & management
- Podcast
- Questions & discussion
- Pitfalls
definition
- Acute colonic pseudo-obstruction refers to a paralytic ileus of the colon which causes severe colonic dilation. In some cases the small bowel may also be involved.
- This is not due to anatomic obstruction, but rather due to hypomotility.
physiology
- The tension on the bowel wall is proportional to the radius (based on Laplace's Law, figure below). Therefore, as the colon dilates, this increases the wall tension, which may decrease blood flow to the colon. Decreased motility with gas accumulation adds to the vicious spiral wherein increased wall tension causes the colon wall to stretch further – which in turn increases the radius, further increasing the wall tension. The net result is progressive dilation with eventual perforation, if left unchecked.
- Decompression of the colon is needed, before the colon dilates beyond a point of no return.
contexts
- Occasionally, patients may present to the hospital with an initial presentation caused by colonic pseudo-obstruction.
- More commonly, colonic pseudo-obstruction develops as a nosocomial complication. For example,
- As a postoperative complication (especially following orthopedic or gastrointestinal surgery, with prolonged immobility).
- Arising in the context of mechanical ventilation (especially among patients on continuous infusion of opioid analgesia).
manifestations
- Abdominal distension, often with tenderness. (However, note that severe tenderness should raise concern regarding the possibility of colonic pseudo-obstruction leading to bowel perforation.)
- Nausea and vomiting.
- Inability to pass stool or flatus is common, but not always seen (up to 40% of patients may continue to pass flatus and feces). (33354038)
- 💡 Bowel movements don't exclude acute colonic pseudo-obstruction. (37486594)
- Intubated patients may present with tube feeding intolerance, distension, and reduced stool output.
- Rarely, dyspnea or respiratory failure may occur (due to impaired diaphragmatic compliance).
manifestation of progressive colonic pseudo-obstruction:
- In the advanced state, pseudo-obstruction may progress to perforation causing septic shock.
- Abdominal compartment syndrome may also result.
- Fecal impaction.
- Distal mechanical obstruction of the colon:
- Malignancy.
- Volvulus.
- Incarcerated hernia.
- Toxic megacolon:
- Inflammatory bowel disease (especially ulcerative colitis).
- C. difficile. 📖
- Chronic intestinal pseudo-obstruction (CIPO):
- Often related to underlying neurologic abnormalities (e.g., autoimmune, paraneoplastic, or myopathy).
- Review of old imaging may be useful to establish chronicity. (37486594)
physical examination
- The abdomen is generally distended and tympanitic.
- Among conscious patients, peritoneal signs may suggest critical distension (causing bowel wall ischemia) or possibly perforation.
- Rectal examination may be helpful to evaluate for impaction.
abdominal radiograph
- Role of abdominal radiograph:
- Usually the first imaging study obtained.
- Serial abdominal radiographs may be helpful to follow the course of the illness.
- The hallmark finding is colonic dilation, especially involving the cecum, ascending colon, and transverse colon. (33354038) This often involves considerable amounts of gas.
- If dilation extends to the rectum this is reassuring (arguing against mechanical obstruction or volvulus).
- There should be normal haustral markings.
- A moderate amount of small intestinal dilation and air-fluid levels may also be seen.
- The size of the cecum is critical:
CT abdomen/pelvis
- CT scan is generally advisable, to exclude alternative diagnoses (e.g., mechanical obstruction, toxic megacolon).
- Rectal contrast may increase risk of perforation and should be avoided.
sepsis
medications
- Opioids.
- Anticholinergics, for example:
- Antipsychotics, tricyclics
- Antihistamines
- Muscle relaxants (e.g., baclofen, cyclobenzaprine, tizanidine)
- Parkinson's disease medications
- Calcium channel blockers.
- Alpha-adrenergic agents.
- Clonidine, dexmedetomidine.
electrolyte or metabolic abnormalities
- Electrolyte abnormalities (especially hypokalemia, hypocalcemia/hypercalcemia).
- Uremia.
- Hyperglycemia.
- Hypothyroidism.
neurological disorders
- Spinal cord lesions.
- Stroke.
- Parkinson's disease.
- Dementia (including Alzheimer disease).
abdominal pathology
- Recent surgery.
- Peritonitis, appendicitis, cholecystitis, pancreatitis.
- Intestinal ischemia.
#1) exclude impaction, perforation, or mechanical obstruction
- CT scan is generally advisable to exclude perforation or mechanical obstruction.
#2) consider surgical consultation
- When to consider consulting a surgeon:
- Cecum diameter is >12 cm.
- Abdomen is very tender, raising concern for impending perforation or ischemia.
- Absolute indications for surgery are limited (e.g., bowel perforation or bowel infarction).
- The perioperative mortality is enormous (~25%), so surgery is generally avoided if at all possible. Even if the cecum is severely dilated, a trial of neostigmine may still be less dangerous than surgery.
#3) neostigmine
timing of neostigmine
- Many sources recommend delaying neostigmine for a period of “conservative management.” However, neostigmine is generally quite safe and effective when monitored properly. Prompt administration may prevent colonic pseudo-obstruction from worsening.
contraindications to neostigmine
- CT scan abnormalities, including:
- Mechanical bowel obstruction.
- Signs of peritonitis or perforation.
- Urinary obstruction.
- Bradycardia, hypotension.
- Active asthma exacerbation.
- Renal insufficiency.
- Seizure disorder (relative contraindication; caution advised).
- Pregnancy.
potential complications of neostigmine
- Bradycardia.
- Hypersalivation.
- Bronchospasm.
- Nausea/vomiting.
- Abdominal pain.
technique for neostigmine administration
- Give 2 mg over 5 minutes (⚠️ do not give neostigmine as a rapid IV push).
- This needs to be a real five minutes.
- There is a small risk of bradycardia, which may be treated with atropine or epinephrine infusion. Resuscitation equipment and medications should be present to manage this if necessary.
- Traditional management of bradycardia is atropine, but atropine will inhibit the activity of neostigmine on the bowel. A low-dose epinephrine infusion could have the advantage of improving the heart rate, while allowing the neostigmine to still treat the pseudo-obstruction.
- Efficacy is >80%. (36227004) If neostigmine fails to work, a second 2-mg dose can be repeated 3 hours after the initial dose (the half-life is ~50 minutes).
neostigmine infusion
- van der Spoel et al. (2001) showed that a neostigmine infusion (0.4-0.8 mg/hr for 24 hours) was effective in a small randomized controlled trial (as compared to placebo). (11430537)
- Smedley et al. (2020) published a retrospective study comparing bolus versus continuous infusion neostigmine. Continuous infusion was associated with a greater reduction in bowel diameter (73% vs. 40%; p = 0.004). The continuous infusion was associated with a higher rate of bradycardia, but no difference in atropine administration. (30373445)
- Neostigmine infusion may be considered for patients who don't respond to bolus doses.
oral pyridostigmine
- Oral pyridostigmine has been used for colonic pseudo-obstruction. Interestingly, some reports suggest success using extremely low doses (e.g.,10 mg BID with escalation to 30 mg BID). (37486594) One RCT found 60 mg of pyridostigmine to be effective in postoperative ileus. (29734770)
- Scheduled pyridostigmine (e.g., 60 mg PO q6hrs) may be considered as an alternative to a neostigmine infusion, especially if a neostigmine infusion isn't logistically feasible. There isn't high-level evidence regarding the use of pyridostigmine in colonic pseudo-obstruction. However, pyridostigmine is commonly utilized in myasthenia gravis among ambulatory patients with a well-tolerated side effect profile. ⚡️ Therefore, the safety profile of pyridostigmine is arguably better established than a neostigmine infusion.
neostigmine-glycopyrrolate cocktail?
- Glycopyrrolate is an anticholinergic agent which will tend to increase the heart rate and also reduce bowel motility. Neostigmine seems to act more strongly on the heart than the gut.
- Adding glycopyrrolate to neostigmine reduces the risk of bradycardia. Adding glycopyrrolate could theoretically reduce the efficacy of neostigmine on pseudo-obstruction, but a study in patients with spinal cord injury found that the combination was as effective as neostigmine alone. (15984982, 18338263, 28893807)
- Currently, neostigmine monotherapy remains the preferred therapy for most patients. However, combined therapy could be useful for patients at an increased risk of bradyarrhythmia.
- A commonly used combination is 2 mg neostigmine plus 0.4 mg glycopyrrolate.
#4) additional medical management package
NPO
- Discontinue enteral feeding until pseudo-obstruction has improved.
- However, there is no evidence to support nasogastric drainage.
evaluate and treat any reversible causes, e.g.: ⚡️
- Antimotility drugs and opioids should be discontinued or weaned as possible.
- Enteral naloxone should be considered for patients on moderate to high doses of opioids (more on this here).
- Electrolyte abnormalities should be treated.
- Mobilization should be undertaken as able (ideally ambulation, but frequent side-to-side repositioning in bed may also be helpful).
follow for improvement or deterioration
- Serial clinical examination.
- Serial abdominal radiographs (q12hr-q24hr). (37486594)
other potential therapies:
- Prucalopride is a 5HT-4 agonist that increases colonic motility with off-label use for chronic intestinal pseudo-obstruction. (36227004) Two case reports have described successful use of prucalopride in patients with acute colonic pseudo-obstruction refractory to other measures. (37486594)
#5) failure of commonly employed therapies
options include:
- [1] Decompressive colonoscopy (with or without insertion of a rectal tube). Both the ASGE (American Society of Gastrointestinal Endoscopy) and the ESGE (European Society for Gastrointestinal Endoscopy) recommend endoscopic decompression for patients with cecal diameter >12 cm and symptoms persisting for >48-72 hours despite medical management. (37486594) Colonoscopy of a dilated and unprepared colon increases the risk of perforation, which may occur in ~2% of procedures. (35966377)
- [2] Surgery (e.g., subtotal colonic resection).
- [3] Neostigmine infusion or scheduled oral pyridostigmine.
Consult with gastroenterology and/or surgery. There is no clear evidence, so the optimal management should be tailored to a specific patient.
#6) recurrence prevention
- Polyethylene glycol may reduce the likelihood of recurrent colonic pseudo-obstruction. (37486594)
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- If untreated or managed conservatively (“wait-and-see” approach), colonic pseudo-obstruction may lead to cecal perforation.
- Colonic pseudo-obstruction will usually respond nicely to prompt administration of IV neostigmine. The best approach is generally prompt medical therapy.
- Treatment with osmotic laxatives will make this worse (e.g., polyethylene glycol or especially lactulose). Be careful of treating constipation blindly with an escalating regimen of laxatives. However, after resolution of an acute episode, a maintenance regimen of polyethylene glycol may help prevent recurrence.
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References
- 11430537 van der Spoel JI, Oudemans-van Straaten HM, Stoutenbeek CP, Bosman RJ, Zandstra DF. Neostigmine resolves critical illness-related colonic ileus in intensive care patients with multiple organ failure–a prospective, double-blind, placebo-controlled trial. Intensive Care Med. 2001;27(5):822-827. doi:10.1007/s001340100926 [PubMed]
- 15984982 Korsten MA, Rosman AS, Ng A, et al. Infusion of neostigmine-glycopyrrolate for bowel evacuation in persons with spinal cord injury. Am J Gastroenterol. 2005;100(7):1560-1565. doi:10.1111/j.1572-0241.2005.41587.x [PubMed]
- 18338263 Rosman AS, Chaparala G, Monga A, Spungen AM, Bauman WA, Korsten MA. Intramuscular neostigmine and glycopyrrolate safely accelerated bowel evacuation in patients with spinal cord injury and defecatory disorders. Dig Dis Sci. 2008;53(10):2710-2713. doi:10.1007/s10620-008-0216-z [PubMed]
- 26034408 Chudzinski AP, Thompson EV, Ayscue JM. Acute colonic pseudoobstruction. Clin Colon Rectal Surg. 2015;28(2):112-117. doi:10.1055/s-0035-1549100 [PubMed]
- 28818187 Vilz TO, Stoffels B, Strassburg C, Schild HH, Kalff JC. Ileus in Adults. Dtsch Arztebl Int. 2017;114(29-30):508-518. doi:10.3238/arztebl.2017.0508 [PubMed]
- 28828195 Vazquez-Sandoval A, Ghamande S, Surani S. Critically ill patients and gut motility: Are we addressing it?. World J Gastrointest Pharmacol Ther. 2017;8(3):174-179. doi:10.4292/wjgpt.v8.i3.174 [PubMed]
- 28893807 Adiamah A, Johnson S, Ho A, Orbell J. Neostigmine and glycopyrronium: a potential safe alternative for patients with pseudo-obstruction without access to conventional methods of decompression. BMJ Case Rep. 2017;2017:bcr2017221249. Published 2017 Sep 11. doi:10.1136/bcr-2017-221249 [PubMed]
- 29720852 Ladopoulos T, Giannaki M, Alexopoulou C, Proklou A, Pediaditis E, Kondili E. Gastrointestinal dysmotility in critically ill patients. Ann Gastroenterol. 2018;31(3):273-281. doi:10.20524/aog.2018.0250 [PubMed]
- 30294835 Deane AM, Chapman MJ, Reintam Blaser A, McClave SA, Emmanuel A. Pathophysiology and Treatment of Gastrointestinal Motility Disorders in the Acutely Ill. Nutr Clin Pract. 2019;34(1):23-36. doi:10.1002/ncp.10199 [PubMed]
- 30855322 Plummer MP, Reintam Blaser A, Deane AM. Gut dysmotility in the ICU: diagnosis and therapeutic options. Curr Opin Crit Care. 2019;25(2):138-144. doi:10.1097/MCC.0000000000000581 [PubMed]
- 31542890 Caroselli C, Soardi GA, Zaccaria E, Bruno G. Acute colonic pseudo-obstruction: a syndrome due to many causes [published online ahead of print, 2019 Sep 21]. Intern Emerg Med. 2019;10.1007/s11739-019-02190-5. doi:10.1007/s11739-019-02190-5 [PubMed]
- 33354038 Govil D, Pal D. Gastrointestinal Motility Disorders in Critically Ill. Indian J Crit Care Med. 2020 Sep;24(Suppl 4):S179-S182. doi: 10.5005/jp-journals-10071-23614 [PubMed]
- 35966377 Arthur T, Burgess A. Acute Colonic Pseudo-Obstruction. Clin Colon Rectal Surg. 2022 Aug 12;35(3):221-226. doi: 10.1055/s-0041-1740044 [PubMed]
- 36227004 Salamone S, Liu R, Staller K. Gastrointestinal Dysmotility in Critically Ill Patients: Bridging the Gap Between Evidence and Common Misconceptions. J Clin Gastroenterol. 2023 May-Jun 01;57(5):440-450. doi: 10.1097/MCG.0000000000001772 [PubMed]
- 37486594 Sen A, Chokshi R. Update on the Diagnosis and Management of Acute Colonic Pseudo-obstruction (ACPO). Curr Gastroenterol Rep. 2023 Sep;25(9):191-197. doi: 10.1007/s11894-023-00881-w [PubMed]