The huge sale of cathartics and the large variety of preparations offered for the treatment of constipation are not an index of their value and need, but rather serve to emphasize the misconceptions which exist in relation to colon function. The volume of stool evacuated is governed by the quantity of fibre in the food ingested. The frequency of stool passage is related to the size of the colon, and the state of irritability of the rectum and sigmoid. A daily evacuation may be as normal for one individual as one every two or three days is for another. An unduly rigid concept of the necessity of daily evacuation is often followed by the habitual use of cathartics, resulting in overstimulation and irritability of the intestine by increasingly potent drugs. Flatulence, abdominal pain, and even heartburn can be the result of the motility disorder thus induced. Thus, for the most part, treatment of functional constipation is the management of a patient with laxative addiction.

Bowel Re-Education

To successfully handle patients with laxative addiction, all laxatives must be stopped and a brief, simple explanation given regarding the physiology of colon function and defecation; emphasis should be placed on the necessity of an adequate fluid intake and the importance of a breakfast sufficient to stimulate peristalsis. Time must be provided so that the individual can go to the bathroom before leaving for business or school in the morning, or at least a regular time for defecation should be established. The patient must understand that it is impossible to establish a normal rhythm of defecation as long as the laxatives and enemas are continued. The apprehensive patient may be helped initially by the rectal instillation with a bulb syringe of 2 oz. of olive or corn (Mazola) oil at bedtime. This keeps the rectal contents soft and gives the patient something to evacuate in the morning. This procedure is seldom needed after the first few days but may be continued until a regular habit is re-established. The patient must understand that failure to have a bowel movement daily at the outset is not critical; encouragement to persist in the regimen is essential to success. Initially, when bowel irritability is present, phenobarbital gr. ¼ combined with atropine gr. 1/100 to 1/200 three times daily before meals (t.i.d., a.c.) may be of help. In this stage, also, a diet with a large amount of fibre is not well tolerated and both fruit and vegetables often have to be eliminated until irritability, as judged by pain or flatulence, has subsided. Bland fruits, such as bananas, can then be started, progressing to the addition of more laxative fruits such as prunes. The laxative quality of the food may be increased by the addition of lactose, 2-4 oz. daily.

Physical Aids to Defecation

In addition to this bowel re-education program, other aids to defecation should not be overlooked. These include, especially in the training of children, proper posture with thighs flexed on the abdomen and feet on the floor or adequate support so that good use can be made of the abdominal musculature. Abdominal exercises may be indicated, and when the pelvic floor has been weakened, levator ani exercises should be prescribed.

Special Problem Patients

Bed-ridden patients — Bed-ridden patients and those with anal lesions require special consideration. When a patient is confined to bed and has to cope with the discomfort and indignity of a bed pan, constipation leading to impaction must be prevented by the use, when possible, of a bedside commode and by avoiding constipating medications. In many patients, straining is contraindicated and may be avoided by the regular and nightly use of the mildest possible laxative which will achieve the desired result. In order of preference, milk of magnesia, an anthracene derivative or a hydrophilic colloid may be used. Anal fissure or inflammation of the anus, with or without hemorrhoids, may contribute to constipation through locally induced reflex sphincter spasm. It is most desirable in this instance that the patient have a well-lubricated, soft, single stool daily. Sitz baths and local anesthetic agents may be used along with mineral oil to achieve this objective.

Classification of Cathartics

Agents increasing the intestinal bulk. — Those which increase intestinal bulk by osmotically attracting water into the small intestinal lumen include the saline cathartics. The most drastic of these is magnesium sulfate (45-60 c.c. of saturated solution); less drastic but bad-tasting is sodium sulfate (15 g. in saturated solution). Milk of magnesia (aqueous solution of magnesium oxide) 15-30 c.c. gives a mild laxative action by the same general mechanism. Hypertonic sodium phosphate enemas (Fleet or Travad, 4 fl. oz.) act by a similar mechanism on the rectum and sigmoid and are effective and safe.

In the same general group are the hydrophilic colloids including dried fruits such as figs, apricots and prunes, methyl cellulose in tablet form (sodium carboxymethylcellulose U.S.P., Carmethose 1-2 tablets in water), and a wide variety of agents derived from gums or seeds, such as psyllium hydrophilic mucilloid (Metamucil, 1-2 teaspoonsful in water) and Plantagoovata (Konsyl, 1-2 teaspoonsful in water), Plantagoloeflingii, a vegetable hemicellulose (Mucilose, 1-2 tablets in water), and many other similar preparations.

All of these bulk-producing agents, which should be taken with a large glass of water, act by increasing the volume of intestinal contents, and so encourage normal reflex bowel activity. Their greatest use in functional constipation is when dietary intake is lacking in fibre content, or they may be substituted for bulk-containing food in people with irritable colon syndrome. They are best taken in the morning, since they require in most instances one to three hours to act. These should not be used by patients under treatment with ganglionic-blocking agents, where constipation is best treated by cascara or senna.

Agents lubricating the stool — The only preparation of importance in this category is mineral oil (liquid petrolatum, 15-45 c.c. at night). Flavouring is added in some preparations for increased palatability. Wetting agents or stool softeners, dioctyl sodium sulfosuccinate (Colace or Regulex, 200-240 mg. two to three times daily), soften the stools and appear to allow a better admixture of stool with mineral oil. I have not been greatly impressed with the value of these agents.

Agents producing catharsis by irritation. —Castor oil, the most potent of this widely used group, affects the small bowel in a matter of a few hours, and should not be used in functional constipation. Compound powder of senna, 10 g., acts in much the same way as castor oil. Senokot (the total active principle of Cassia acutifolia pods), 1-2 teaspoonsful at bedtime, is a milder-acting member of this family. A milder irritant of the anthracene group which stimulates only the colon is aromatic Cascara sagrada fluid extract (1-2 ml. at bedtime). Bisacodyl (Dulcolax, 5-mg. tablets, two to three at bedtime) is a newer colonic irritant preparation of great current popularity. This is also available as a 10-mg. suppository, which exerts its irritant action only on the rectum.

Enemas. —Tap water at body temperature is the most satisfactory enema when irritation of the colon is to be avoided (500-1500 c.c). Reference has been made to the hypertonic phosphate enemas. Soapsuds enemas produce their action by water stimulation and soap irritation, and are contra-indicated in inflammatory conditions of the colon.

Oil retention enemas of either corn oil (Mazola) or olive oil are useful to soften and lubricate hard fecal masses, and have their greatest value in the relief of fecal impaction and in the management of acutely painful anal lesions.

The patient presented a classic example of constipation resulting from narcotic analgesic administration, without any concomitant laxative program. An unnecessary hospital admission, a great deal of discomfort for the patient, and an unpleasant task for the nursing staff could all have been avoided.

As a physician working in palliative care, I have been continually confronted with patients’ problems of constipation. No other preventable symptom produces so much distress for the patient and the caring family. It is common for physicians either to omit completely any prescription for laxatives or to write a prescription for laxatives “as needed” or ‘laxative of choice” and to leave further management to nurses. The implication is that laxatives are administered only when constipation is present, as a treatment, rather than on a regular, individually adjusted, dosage schedule to prevent further problems.

Constipation is defined as a decrease in the frequency of bowel movements accompanied by a prolonged and difficult passage of feces, followed by an uncomfortable sensation of incomplete evacuation. Frequency of bowel movements can vary from three weekly to three daily, so what is constipation for one patient can be normal for another. Careful evaluation of constipation will require attention to frequency, consistency of stool, and ease of evacuation. Several symptoms can appear: low back pain, abdominal distress, distension, or flatulence.

Incidence

Obstinate constipation was described by Bockus as one of the most common conditions that the physician is called upon to treat, and one of the most often mismanaged.

Constipation is a common and distressing symptom in cancer patients. St. Christopher’s Hospice in London, England, reported that 45% of male patients and 43% of female patients on admission complained of constipation. At Sir Michael Sobell House, Oxford, 78% of patients on morphine received a laxative. The incidence of the problem’s occurring at some time during the course of the disease approaches 100%.

Causes in Cancer Patients

Contributing Factors

Certain contributing factors are particularly common in cancer patients and should be evaluated in any differential diagnosis.

1. Physiologic factors include advanced age, decreased exercise, especially in those who are bedridden, decreased bulk in diet, dehydration, inconvenience (inability to reach the toilet when the urge to defecate is present), depression, diminished awareness of loaded rectum, and poor dentition leading to inadequate nutrition.

2. Structural (anatomical-pathologic) factors include intracolonic (partial bowel obstruction, diverticulosis, tumour, bleeding, irritable or “cathartic colon,” ischemic colitis, and stricture), extracolonic (tumour or ascites), and anal (fissure, hemorrhoids, stricture, and proctitis from radiation).

3. Metabolic factors include hypercalcemia, hypokalemia, and uremia.

4. Neurologic factors include neuropathy (chemotherapy-induced or diabetic), compression of nerve roots or of spinal cord, and cauda equina.

5. Drugs affecting the bowel include opiates, antacids (calcium and aluminum compounds), anticholinergic drugs (belladonna alkaloids), antidepressive agents, phenothiazines, anticonvulsants, and diuretics.

Narcotics

Opiates increase the tone and non-propulsive motility of both ileum and colon. There is ample evidence that the opiates have both local effects on the gut and central nervous effects producing changes in motility of the bowel.

Treatment

Initially simple measures should be tried, such as increasing dietary fibre and increasing fluid intake. Patients should be encouraged to have a bowel movement when the urge occurs by providing a commode that is easily accessible. Almost always an additional systematic laxative regimen will be needed for cancer patients receiving narcotics.

All laxatives work by increasing motor activity, which promotes peristalsis, or by altering hydration of the stool. Physicians need to be acquainted with only a few agents in order to prescribe appropriately. Most effective is the use of a combination of a stool softener and a stimulant. A stimulant alone can lead to abdominal cramps. If a softener alone is given, the patient can develop a loaded rectum with soft stool.

Laxatives

Laxative drugs can be divided into five groups: bulk agents (regulators), lubricants and stool softeners, small bowel flushers (salts and non-absorb-able sugars, i.e., osmotic drugs,) stimulants, and anthracenes. Their site of action is indicated in Table 1.

Bulk Agents. Dietary fibre retains several times its weight in water. Foods containing wheat bran and fibre are particularly useful in chronic constipation, but the anorexia so common in advanced cancer limits dietary intake. Psyllium (Metamucil et al.) will increase the water content of the stool as well as the rate of colonic transit. A high fluid intake is required, a limiting factor in most patients with advanced disease. Dietary fibre and bulk agents are contra-indicated in intestinal obstruction, whether partial or complete.

Lubricants and Stool Softeners. Docusate sodium (Colace, Regulex, et al.) is a detergent that acts by drawing water and sodium into the bowel lumen. The dosage is regulated according to the consistency of stool, usually 100 to 600 mg/ day. (It is one of the most commonly used agents in Britain and in the United States.) Mineral oil, liquid paraffin, and other lubricants are contra-indicated. There is an ever-present risk of aspiration pneumonia, and when used for a longer term, of interference with absorption of fat-soluble vitamins. Mixtures of mineral oils with other cathartics is irrational.

Osmotic Agents. Saline cathartics usually contain magnesium or sodium ions, which retain fluid in the large bowel by osmotic pressure. These ions usually act in one or two hours. The major hazard of saline laxatives is their potential to cause electrolyte disturbances, especially in the elderly, who have a diminished capacity to return to an electrolyte balance. Partial absorption of sodium or magnesium can cause toxic effects in patients with cardiac or renal failure.

These agents are most effective if accompanied by a large oral intake of fluids. Commonly used saline cathartics include sodium sulphate, sodium phosphate, magnesium sulphate (Epsom Salt), magnesium hydroxide, and magnesium citrate. Lactulose (Chronulac, Lactulax, et al.) is a non-absorbable sugar that exerts similar osmotic effect. It is reported to be useful in patients with exacerbated abdominal discomfort. It is tolerated better than other drugs by some patients, but is also more costly.

Stimulants. Surface wetting agents and stimulant laxatives both work chiefly on contact with the intestinal mucosa. Contact laxatives change the absorption of water and electrolytes by the mucosa of the gut and soften the feces. The stimulant laxatives all enhance propulsive peristalsis. Because the effect is delayed for six to nine hours, they are best taken at bedtime. Examples include bisacodyl (Dulcolax et al.) by tablet or suppository.

Included in the anthracenes are cascara and senna, both containing glycosides. Senna, a contact laxative, is activated by bacterial action in the large bowel. It is usually prescribed in tablets or granules but is also available in liquid (X-Prep).

Rectal Measures

Suppositories. A combination of one glycerine suppository (which attracts water into the rectum) and a bisacodyl suppository (which stimulates the musculature) is often effective. Suppositories should be placed against the mucosal wall rather than pushed into the stool. Suppositories work quite quickly and should be given 30 minutes before breakfast or supper to take advantage of the gastrocolic reflex. Suppositories, when used regularly for several weeks, can cause a mild proctitis.

Enemas. A phosphate enema (Fleet) can help to evacuate the lower rectum. If stool is higher in the colon, a normal saline enema can be tried. If ineffective, an oil enema, delivered high up in the rectum and retained for about two or three hours, if possible, will soften stool; if expelled, it can be followed by a cleansing enema.

ManualDisimpaction. Impaction is the result of incomplete evacuation over time. The most common symptoms are rectal discomfort, rectal fullness, and tenesmus. There can be associated overflow incontinence of small amounts of liquid stool. The fecal impaction can be removed in patients who are not too sick by softening the mass from above using a stool softener. If this is not advisable, a gentle rectal examination is performed, using a single finger lubricated with 5% lidocaine ointment. After a few minutes, another finger can be inserted, which allows for dilatation of the anal sphincter without causing too much pain. The fingers are then used to “slice up” the impacted fecal mass. Several cleansing enemas are administered after removal of the pieces of stool. High fluid intake is mandatory on the day of disimpaction.

Rarely patients will require intravenous diazepam before the procedure to assist relaxation. In some centres a mixture of 50% nitrous oxide and 50% oxygen (Entonox) is used by inhalation for analgesia during the procedure.

Bowel Management

Proper assessment is the first step in the management of constipation. The patient should be asked about bowel habits and the use of laxatives.

Regular supervision of the laxative regimen by the physician and the nurse will be assisted by use of a recording form, where bowel movements, laxatives used, and other interventions can be noted daily. If the patient has not had a bowel movement for three days or more, the rectum should be examined for impaction. A plan should be developed by the physician in consultation with the attending nurse (Figure 1).

Conclusion

Constipation can be considered an iatrogenic complication. Indeed, constipation is one of the most frequent and distressing symptoms in cancer patients. Too frequently it becomes a major problem if the constipating potential of other drugs is not recognized. When anticipated, constipation can be easily managed by using a protocol, as suggested above. An appropriate recording form, especially when the patient is at home, will facilitate communication between the patient, nurse, and physician. It will assist in the successful prevention of constipation in