Makindo Medical Notes

Related Subjects: Small Bowel Obstruction | Colonic (Large bowel) Obstruction | Caecal Volvulus | Small Bowel Ischemia | Hartmann's procedure | Sigmoid Volvulus | Acute Colonic Pseudo-obstruction |

The acute use of an anticholinesterase such as neostigmine has been shown to cause rapid resumption of normal activity, adding weight to the aetiological theory of autonomic nerve dysfunction. Decreased parasympathetic tone vs increased sympathetic tone of the left colon can cause functional obstruction.

About

• The clinical picture resembles that of mechanical bowel obstruction

Physiology

• There are two main neurotransmitters in the enteric nervous system.
• Acetylcholine, which increases intestinal secretions and motility
• Noradrenaline, which decreases both intestinal secretions and motility.

Aetiology

• Impaired bowel peristalsis and function
• Failure of intestinal motility
• Loss of autonomic control of bowel function
• Excessive sympathetic inhibitory activity
• Diminished prokinetic cholinergic drive

Risk factors

• Patient often elderly with multiple comorbidities
• Myocardial infarction, Pneumonia, Fractured hip, Trauma
• Increasing Age, drugs, Hypothyroid, COPD
• Immobility, electrolytes, sepsis
• Baclofen, Opiates, Antidrepressants
• SLE, Myasthenia, MS, Amyloidosis, Mitochondrial diseases

Clinical

• Abdominal pain, distension and vomiting
• Failure of flatus PR, Enlarging abdominal circumference.

Differentials

• Colonic obstruction e.g. tumour or adhesions or volvulus

Investigations

• FBC, U&E, TFT, Ca, Glucose
• AXR - shows any free air from perforation and caecal diameter and bowel diameter
• Colonoscopy to exclude colonic lesions. May not need to reach the caecum as the hepatic flexure usually enough
• Water contrast enema - again excludes obstruction

Complications

• Perforation (usually of caecum) - usually in elderly, when caecal diameter > 14 cm and failure to decompress
• Peritonitis, death.

Management

• Once the mechanical obstruction is excluded by contrast enema or CT then the patient should be treated conservatively with NG and flatus tubes for at least 48 hours
• Assess precipitating factors that should be treated. Review and stop unhelpful medications and correct electrolytes. and ensure hydration.

Medical Management

• Consider Prucalopride (used off-licence for refractory ACPO) 1-2 mg od PO. Prucalopride is a highly selective serotonin 5-HT4 receptor agonist which has been shown to stimulate gut motility in vitro and in vivo
• If no response then Neostigmine 2 mg given IV over 5 minutes. This can be repeated. May cause bradycardia
• Earlier mobilisation and positioning of patients - get them out of bed.
• Nutrition: if prolonged may need Total Parenteral Nutrition (TPN) but needs HDU/ITU setting.

Interventional Management

• Endoscopic colonic decompression: if caecal diameter >9 cm.
• When there is a risk of impending perforation of the caecum from massive colonic dilatation and colonic ischaemia, it should be dealt with by caecostomy or hemicolectomy.
• In spite of available medical and surgical interventions, the outcome remains poor.

References

• Acute Colonic Pseudo-obstruction