Diarrhea is a common symptom in patients nearing the end of life. It can cause significant discomfort and distress for both patients and families. Understanding the causes and best management strategies is important to optimize quality of life.
What is diarrhea?
Diarrhea is defined as loose, watery stools occurring more than 3 times per day. Stools often contain mucus and may contain blood. Diarrhea results from an imbalance in the absorption and secretion of fluid and electrolytes in the intestines.
Normal stool consistency reflects adequate absorption of water and electrolytes. Diarrhea occurs when:
- There is excess secretion of fluids into the intestinal lumen
- There is reduced absorption of fluids and electrolytes
- Transit time through the intestines is too rapid
What causes diarrhea in end of life patients?
There are several factors that contribute to the development of diarrhea at the end of life:
Medications
Many commonly used medications can cause diarrhea as a side effect. These include:
- Antibiotics – disrupt normal gut bacteria leading to osmotic diarrhea
- Chemotherapy – damages rapidly dividing cells like those lining the gut
- Antihypertensives – some calcium channel blockers and ACE inhibitors affect gut motility
- Laxatives – stimulate intestinal secretion and colonic contractions
- Prokinetic drugs – increase gut motility and decrease transit time
- Antacids containing magnesium – osmotic effect draws water into the colon
Malabsorption
Malabsorption occurs when there is a reduction in the intestine’s ability to absorb fluids, electrolytes and nutrients from food. This leads to osmotic diarrhea as unabsorbed molecules draw water into the gut lumen. Common causes include:
- Impaired gut immune and enzyme function – cancer can inhibit digestive enzymes and immunity
- Small intestinal bacterial overgrowth – more common in illness due to reduced gut motility
- Bile acid malabsorption – can occur after surgery to the ileum where bile acids are absorbed
Disrupted gut microbiome
The gut microbiota play an important role in maintaining the balance between secretion and absorption in the intestines. Disruption to the normal gut flora can occur due to:
- Antibiotics – reduce overall microbial diversity and beneficial species
- Chemotherapy – toxicity damages epithelial cells and microbiota
- Proton pump inhibitors – alter gastric pH impacting bacterial populations
- Poor nutrition – essential nutrients for bacterial growth are lacking
This dysfunction allows potential pathogens to dominate, causing inflammation, impaired electrolyte transport and secretory diarrhea.
Increased gut transit time
Rapid movement of intestinal contents reduces the time available for fluid and electrolyte absorption. This can occur with:
- Disease progression – cancer infiltration can affect enteric nerves
- Neuroendocrine tumors – may secrete hormones/neurotransmitters affecting motility
- Gastric stasis – leads to intestinal hurry as undigested food enters small bowel
- Anxiety and depression – stress hormones impact gut function
Direct mucosal damage
In some cancers, the disease may directly infiltrate or compress the intestines. This disrupts the mucosal lining leading to inflammation, ulceration and secretory diarrhea. Radiation used to treat abdominal and pelvic cancers can also damage the bowel wall.
Other factors contributing to diarrhea
- Dehydration – impairs electrolyte and water reabsorption
- Hyperglycemia – osmotic effect
- Tube feeding – high osmolality formulas move quickly through the gut
- Infections – viruses, bacteria and Clostridium difficile may cause diarrhea
What are the consequences of diarrhea?
Diarrhea, especially when severe, can lead to:
- Dehydration and electrolyte imbalances – due to fluid losses
- Impaired nutrient absorption – worsens nutritional status
- Perianal skin breakdown – from frequent, loose stools
- Patient distress – constant need to defecate is socially disruptive
- Disturbed sleep – due to urgency and discomfort
- Caregiver burden – from frequent linen changes, sanitation needs
If not managed effectively, persistent diarrhea hastens decline and negatively impacts quality of life.
How is the cause diagnosed?
Determining the underlying cause of diarrhea through investigations helps guide management:
- Medication review – stop medications not providing comfort or causing diarrhea
- Stool tests – culture, C. difficile, ova and parasites to look for infections
- Blood tests – glucose, calcium, albumin, electrolytes
- Imaging – CT scan of abdomen/pelvis to assess disease progression
- Endoscopy – visually inspect mucosal inflammation, ulceration, compression
However, extensive testing is often not appropriate for end of life patients. Simple interventions to slow gut motility and improve hydration can be tried first.
What treatments are available?
The goals of diarrhea management in palliative patients are to:
- Slow intestinal transit time
- Improve absorption of fluids/electrolytes
- Protect perianal skin
- Provide patient comfort
This involves both pharmacological and non-pharmacological strategies:
Medications
- Loperamide – decreases gut motility to allow greater water reabsorption
- Tincture of opium – contains morphine which reduces gut secretions and peristalsis
- Octreotide – reduces fluid secretion in the intestines through hormonal effects
- Anti-emetics – ondansetron and metoclopramide slow small bowel transit
- Antibiotics – if infection with C. difficile or other pathogens is confirmed
- Steroids – reduce inflammation in ulcerative gut lesions
Non-pharmacological interventions
- Oral rehydration solutions – replacing lost fluids/electrolytes
- Avoid feeding – giving bowels rest to recover absorptive function
- Low fiber diet – reduces colonic loading and rapid transit
- Radiation therapy – can relieve compression/obstruction from tumors
- Tube feeding beyond the ligament of Treitz – allows bowels to rest
- Perianal skin care – gentle cleansing, barrier creams
Integrative therapies
There is limited evidence for these complementary approaches:
- Probiotics – improve gut microbiome diversity and function
- Glutamine – supports intestinal mucosal health
- Zinc supplements – reduces intestinal permeability
- Psyllium – can slow colonic transit in some patients
What is the likely prognosis?
In most cases, a combination of the above measures can significantly reduce the frequency and severity of diarrhea. However, diarrhea may be difficult to fully resolve if the underlying disease is progressive or not responsive to treatment.
With a terminal prognosis measured in weeks, diarrhea may persist intermittently. The focus shifts to keeping the patient clean, comfortable and avoiding dehydration. Providing dark towels and disposable bed pads can help maintain dignity and independence.
Good hand hygiene for patients and caregivers is essential. For short prognosis measured in days, diarrhea often resolves as oral intake reduces. Parenteral fluids and medications to dry up secretions are helpful comfort measures.
Conclusion
Diarrhea is a common and distressing occurrence for those nearing the end of life due to the impacts of advancing disease and associated treatments. Determining the cause guides selection of pharmacological and non-pharmacological therapies to reduce diarrhea frequency and severity. With a palliative approach, diarrhea can often be well managed to optimize comfort and quality of life.