The college asked about constipation ( a variation on the theme of gut dysmotility) in Question 17 from the first paper of 2016. Colonic pseudo-obstruction was asked about in Question 7 from the first paper of 2018. Gut dysmotility and prokinetic agents are discussed elsewhere, and that topic is kept separate because the discussion there is more about improving the tolerance of incoming enteral feeds. Improving the exit of those feeds is the topic of this chapter. The best short introduction to the topic is probably the 2015 article by JL Vincent and JC Preiser.
Broadly speaking, constipation is associated with inadequate nutrition due to poor feed tolerance, delayed ventilator weaning and slower ICU progress, with some authors reporting an increased ICU stay. The therapy scales up from simple things (stopping the constipating drugs and mobilising the patient) all the way to neostigmine infusion and manual disimpaction.
ESICM have a working group or subcommittee for just about everything ( I am sure they have a team specifically authorised to categorise injuries arising from being sucked into an aircraft engine). These definitions for gut problems have been adapted from their 2012 statement.
According to Nassar et al, (2009), constipation occurred in 69.9% of the patients who stayed for loger than 3 days in the ICU. In other studies, it ranges from 5% to 83% (Azevedo et al, 2013) Factors associated with constipation may include a long list:
Modifiable ICU-related risk factors
Non-modifiable disease risk factors
Constipation seems to be associated with numerous adversities for the critically ill patient:
Consequences of constipation may include:
This is probably a reasonable place to discuss the pointlessness of auscultating bowel sounds in ICU patients. The practice of trying to distinguish normal from pathological bowel sounds has been nicely debunked by van Bree et al (2018), who determined that the reliability of this examination manoeuvre in discriminating ileus from non-ileus was approximately as accurate as tossing a coin.
Tier one therapies and investigations:
Tier two therapies and investigations: Assuming bowel obstruction and megacolon are ruled out
Tier three therapies and investigations: assuming all of the above are ineffective, or impossible to implement
Pharmacological (pro-motility) management
Interventional (decompressive) management
Advantages of surgical decompression are:
The disadvantages are:
This is a therapy supported by a small number of RCTs, all of which in turn had a small number of patients, such that when Valle & Godoy (2014) tried to do a meta-analysis on this, they turned up only 127 patients. A single dose of neostoigmine seemed to resolve colonic pseudo-obstruction in 89.2% of patients. In ICU patients, Van der Spoel et al (2001) used a continuous infusion of 0.4-0.8mg/hr, with similar results (they put 5mg in 50ml syringes and started the infusion at 4ml/hr, in case you are wondering)
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