Constipation is sometimes regarded as a minor symptom by care providers. However, this is not the case with palliative care patients. The prevalence of constipation in the overall population varies from 2% to 28% in population surveys, and it is more prevalent in elderly patients. It is a very prevalent symptom in patients who have advanced, progressive illnesses and is a significant source of suffering. Prevalence rates for constipation are approximately 25% to 50% for those with any type of terminal illnesses. One study indicated that laxatives were administered to 87% of terminally ill patients with cancer. From my personal, on-call experience in a large, home-based palliative care practice, constipation ranks as one of the major reasons for accessing the on-call service after hours. The approach to managing constipation is similar to that of other symptoms: Start with a comprehensive assessment, consider pharmacologic and nonpharmacologic management, follow through with careful monitoring, and be sure to educate the patient, family, and other care providers about the issues and the management.
Definition
Infrequent defecation (fewer than three bowel movements per week) has generally been regarded as the most important marker of constipation. However, other symptoms, such as excessive straining, hard stools, and a feeling of incomplete evacuation, have recently been recognized as equally important and perhaps more common. More formal definitions like the Rome III are used in research studies, but they are not very useful in the clinical situation. A number of scales have been developed to assess the symptom of constipation. The Victoria Hospice Society Bowel Performance Scale is one of several scales currently used in Canada. Other scales include the Bristol Stool Form Scale and the Sykes DISH (Difficulties, Infrequent, Smaller, Straining, Harder) scale. Constipation may be associated with other symptoms and may be the major cause of nausea and vomiting, confusion, agitation, intermittent diarrhea, bloating, and abdominal pain. Rarely, severe constipation can be associated with bowel perforation and sepsis.
Etiology
Constipation has a multifactorial origin, as do other symptoms commonly seen near the end of life. The normal physiology of defecation is complex and involves the central and peripheral nervous system, hormones, and reflexes that are unique to the gastrointestinal system. The peripheral sympathetic and parasympathetic nervous system controls colonic motility, colonic reflexes such as the gastrocolic reflex, and relaxation and contraction of the anal sphincter. The urge to defecate and the process of defecation itself are mediated by the central nervous system and require contraction of skeletal muscles to increase abdominal pressure to facilitate evacuation. Adrenergic, opioid, muscarinic, and dopaminergic receptors all have a role in gut motility. Gastrointestinal hormone physiology is controlled by the endocrine and paracrine systems, as well as by neural pathways. Problems in any one or a number of these systems may lead to constipation.
Opioid-induced constipation is one of the more common problems seen in palliative care. It results from decreased intestinal motility; poor propulsive action leads to prolonged intestinal transit time, increased fluid absorption in the colon, and hard stools. Opioids may also increase anal sphincter tone and may reduce awareness of a full rectum.
Contributing factors, both reversible and irreversible, to constipation in palliative care patients include the following:
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Preexisting constipation. Elderly patients, in particular, have decreased bowel motility for various reasons. Long-term constipation is a problem seen in the general population, especially in women. These patients may also suffer from having taken laxatives for many years, a practice that can result in constipation.
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Neurologic abnormalities. These conditions include spinal cord lesions and autonomic dysfunction or neuropathy seen in diabetes and in cancer.
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Metabolic causes. Conditions include dehydration, uremia, hypokalemia, hypercalcemia, hypothyroidism, and diabetes mellitus.
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Structural obstruction. Conditions include fibrosis from radiation, adhesions, and bowel obstruction from tumors.
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Decreased food, fiber, and fluid intake. Anorexia is a common symptom in many terminally ill patients. It is important to realize that 50% of stool weight is derived from cells, mucus, and bacteria, so even patients who eat very little will produce significant amounts of stool.
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Uncontrolled pain. Uncontrolled pain may limit mobility and the patient’s ability to strain at stool.
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Medications frequently used in palliative care patients, such as certain chemotherapy drugs, opioids, antidepressants, nonsteroidal anti-inflammatory drugs, and others. Even vitamins and minerals commonly taken by patients can add to constipation. All opioids are associated with constipation.
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Limited mobility.
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Generalized weakness. Patients may not be able to sit or develop the increased abdominal pressure needed to evacuate the rectum.
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Hypomotility disorders secondary to diabetes, advanced age, and paraneoplastic problems. These disorders cause increased transit time and ineffective propulsion of stool in the colon.
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Environmental issues. These issues include lack of privacy, change in care setting, the use of bedpans, and inconveniently located washrooms.
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Care provider neglect. Unfortunately, in the hustle and bustle of care, constipation may be overlooked, and protocols to address assessment and management may not be in place. Constipation may be seen as a minor problem and may not be addressed by physicians in particular.
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Patient issues. Patients may be too embarrassed to discuss constipation or may feel that it is a minor symptom. Cultural issues may also hinder a discussion of constipation.
Assessment
A history of decreased frequency and description of hard bowel movements are often the key indicators of constipation. Color, odor, and size of stools should be determined. Patients may report associated symptoms, such as the inability to defecate at will, pain and discomfort when defecating, straining, unproductive urges, flatulence or bloating, or a sensation of incomplete evacuation. However, other symptoms that result from constipation (e.g., nausea or vomiting, generalized malaise, headache, intermittent diarrhea, stool and urine incontinence, abdominal pain, and bloating) may be presenting problems.
Constipation should still be considered even in patients who are anorexic and have limited oral intake, because stools continue to be produced even in the absence of good oral intake (fecal content also consists of unabsorbed gastrointestinal secretions, shed epithelial cells, and bacteria).
Nursing records in institutions often indicate the frequency of bowel movements. A thorough medication history uncovers factors in constipation, including inappropriate or inadequate laxative regimens. A long history of recurring problems of constipation refractory to dietary measures or laxatives often suggests a functional colorectal disorder. An assessment of physical functioning may reveal significant weakness and inability to access washroom facilities. Physical examination may reveal abdominal distention and palpable abdominal masses, fecal and other. Neurologic examination may be required if a spinal cord lesion or brain lesion is suspected.
A gentle rectal examination is essential. Privacy and cultural sensitivities should be taken into consideration before performing a rectal examination. Perineal sensation can be checked. Assess anal sphincter tone, the presence of hemorrhoids and anal fissures, the presence and consistency of stool in the rectum, and the absence of stool and rectal dilation. A lack of stool in the rectum associated with rectal dilation may indicate constipation higher in the left side of the colon or colonic obstruction.
Plain upright radiographic films of the abdomen may be needed when the diagnosis is not evident. A classification system can be used by the radiologist to quantify the degree of constipation, but this is rarely reported or used. However, it can be quite helpful in the patient with difficult-to-control constipation.
Management
General Management Issues
Preventive management is always better than responsive management. For palliative care patients, who tend to be sedentary and often on opioids, a bowel regimen to prevent constipation should be a routine consideration. Other considerations in the management of constipation include the following:
- 1
Correct reversible causes when possible. In most patients, the cause of constipation is multifactorial, so simple changes rarely produce significant change in the problem of constipation. Stopping opioids may, in fact, leave the patient in severe pain. Alternatives to opioids in patients with moderate to severe pain are very limited.
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Prevent constipation. For instance, opioids almost always cause constipation. When opioids are prescribed, a laxative regimen using bowel stimulants and osmotic laxatives should be started immediately, before serious constipation develops. Constipation is one of the most feared adverse effects of opioids. A preventive approach should also be taken with other drugs that commonly cause constipation, such as tricyclic antidepressants.
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Educate the patient, family, and other care providers about the cause of and management plan for constipation. Stress the importance of preventing constipation, thereby avoiding other symptoms and unnecessary suffering. Inquiry about constipation and frank discussions may not be possible in certain cultures. Avoid the cycles of alternating constipation and diarrhea by setting clear protocols for patients and their care providers.
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Create realistic expectations. Although some patients would prefer to have a daily bowel movement, a soft, easy-to-pass movement every 2 days may be the best result.
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Monitor the patient frequently. Pain diaries should also chart bowel movements. Protocols should be in place in all care settings to monitor patients at high risk of developing constipation—that is, most palliative care patients.
Nonpharmacologic Measures
Increase fluid intake if possible. Intake of 2 to 3 L/day is recommended. Too much coffee or tea should be avoided, however, because of the diuretic properties of these fluids. Increase physical activity if possible. Patients may maintain higher levels of function early in the course of a progressive illness. Exercise, even in small amounts, improves bowel motility. A high-fiber diet increases stool weight and accelerates colonic transit time. Daily fiber intake must increase by 450% to increase stool frequency by 50%. A high-fiber diet does not benefit all patients with constipation. Increasing dietary fiber in the palliative care population is often not possible or practical in light of the high prevalence of anorexia, food preferences, and poor intestinal motility, and to do so may actually cause more constipation. Use wheeled bedside commodes to bring patients into washrooms. Ensure adequate privacy for patients. Use of drapes and screens is recommended for patients who cannot be wheeled in a bedside commode to toilet facilities. Avoid the use of bedpans for bowel movements because they are uncomfortable for many patients. Try to ease patients into a regular routine of having a bowel movement at a certain time of the day, usually following some food intake.
Laxatives
A recent evidence-based review of constipation in palliative care patients found that all laxatives demonstrated a limited level of efficacy, and a significant number of participants required rescue laxatives in each of the studies. The authors concluded that “treatment of constipation in palliative care is based on inadequate evidence, such that there are insufficient RCT data. Recommendations for laxative use can be related to costs as much as to efficacy. There have been few comparative studies. Equally there have been few direct comparisons between different classes of laxative and between different combinations of laxatives. There persists an uncertainty about the ‘best’ management of constipation in this group of patients.” The authors also noted that the prescribing preferences of the individual health care provider often prevailed over evidence-based practice.
Two systematic reviews of laxatives have been published. The only clear evidence for laxative efficacy rests with two osmotic laxatives: lactulose and polyethylene glycol (PEG-3350). There is only limited evidence for the efficacy of many commonly used laxatives, including docusate preparations and stimulant laxatives.
For palliative care patients, program algorithms without much evidence base are used with reasonable success, although adverse effects of these regimens are rarely reported. The use of laxatives, often in combination, is a common way to manage constipation. There is reasonable evidence to exclude docusate from most regimens and instead to use lactulose or PEG to soften stools. Many palliative care patients are also put on stimulant laxatives, often in large doses, such as six to eight tablets of sennosides (Senokot) per day, much more than the usual recommended doses. (See Tables 12-1 and 12-2 for specifics; see also the formulary in the Appendix, available online at www.expertconsult.com .) Titrate laxatives to effect. Set up effective protocols that give day-by-day instructions for the family caregiver or nurse. A sample protocol is shown in Table 12-1 .
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