VOL: 100, ISSUE: 20, PAGE NO: 48
Maureen Coggrave, MSc, RN, is research training fellow for ‘Action Medical Research’ at the National Spinal Injuries Centre, Stoke Mandeville Hospital, Aylesbury, and the physiology department, St Mark’s Hospital, Harrow
Normal nervous control of the large bowel
Normal nervous control of the large bowel
The large bowel has an intrinsic nerve supply in the bowel wall, which enables the colon to produce peristalsis. It also has an extrinsic supply, via the vagus nerve and the spinal cord between T10 (thoracic vertebrae) and L3 (lumbar) and S234 (sacral), that modulates and controls colonic motility by influencing the intrinsic system.
Nerves from S2-4 also supply the rectum and anus. They provide reflex control and enable people to feel and voluntarily control the process of defecation. The abdominal muscles play a part when the bowel is evacuated and receive their nerve supply from T6-12.
The impact of SCI on bowel function
After SCI the nerve pathways between the brain and bowel are damaged or severed. Awareness of the need to defecate and voluntary control are lost. Peristalsis continues but is less effective because the brain cannot coordinate it, and therefore stool takes longer to pass through the large bowel. Average colonic transit time in the able bodied is 31.5 (+ or - 17.6) hours; after SCI the average is 86.6 (+ or - 46.9) hours (Leduc et al, 1997), leading to a high risk of constipation. Other effects on the bowel will depend on the part of the spinal cord that is damaged.
Cervical and thoracic injuries In these types of injuries, the reflex arcs connecting the bowel to the spinal cord remain intact. Reflex activity continues but is uncontrolled. The anal sphincters retain their tone and remain closed. When the rectum fills an uncontrolled reflex may cause the sphincters to relax and the rectum to contract. This pushes the stool out of the anus.
This type of function is called upper motor neurone or reflex bowel. The ability to use the abdominal muscles to strain to raise intra-abdominal pressure and initiate defecation may be partially or completely lost.
Lumbar or sacral injuries If the injury is in the lumbar or sacral area (Cauda Equina Syndrome) the reflex arcs connecting the bowel and spinal cord are broken. Consequently, the anal sphincters loose their reflex tone and are relaxed or open, and the lower bowel and rectum are flaccid.
When the rectum fills there is no reflex activity to push the stool out but because the anus is relaxed the stool may be pushed out during any physical exertion or movement that raises intra-abdominal pressure. This function is called lower motor neurone or flaccid bowel.
When people have incomplete spinal injury or non-traumatic spinal cord damage, residual bowel function may be less clearly defined. However, in most people with SCI, active management of the bowel is required to control faecal incontinence and avoid severe constipation.
What is bowel management?
It is a programme of planned interventions with the purpose of achieving regular and predictable emptying of the bowel at a socially acceptable time and place, avoiding constipation, faecal incontinence, and autonomic dysreflexia.
Autonomic dysreflexia is unique to individuals with spinal cord damage above T6. It is an abnormal sympathetic nervous system response to any noxious stimuli below the level of injury. It results in a rapid rise in blood pressure that can be life-threatening if not quickly relieved by removal of the stimulus causing it (Kavchak-Keyes, 2000). After bladder problems, bowel problems are the most common stimulus.
The aim of bowel management is to achieve evacuation within a reasonable time, generally suggested to be under one hour (Stone, 1990). The programme should use the minimum physical or pharmacological interventions necessary and maintain short and long-term gastrointestinal health (Spinal Cord Medicine Consortium, 1998) (Boxes 1 and 2).
The bowel management programme must be acceptable to the individual and should promote her or his physical and verbal independence. An effective programme will promote the eventual reintegration of the person into community living. The programme can be adapted to meet the changing needs of patients as they move from spinal shock to rehabilitation, community living, and ultimately ageing with a disability.
What nursing interventions can be used for bowel management?
Establishing a regular routine is the core of effective bowel management. Management should be conducted at least on alternate days as longer intervals put the patient at risk of constipation.
People with flaccid bowel function should aim for a daily routine of bowel emptying to avoid accidental expulsion of stool through the lax anal sphincters during physical activity. Some people need a twice-daily routine.
For those with a reflex bowel, a daily or alternate-day routine is acceptable depending on individual preference. Once the frequency is chosen it should be adhered to and management conducted at the same time of day on each occasion.
Bowel management has two distinct stages:
- Promoting stool transit through the colon;
- Evacuation of stool from the lower bowel and rectum.
Promoting stool transit
Exercise and activity Physical activity appropriate for the individual patient should be encouraged. This should take into account the patient’s stage of recovery following injury and the level of injury. Exercise can be timed to help with bowel management.
Diet The diet should be evaluated and adjusted according to symptoms including stool consistency and bloating (Box 1).
The gastro-colic reflex Following ingestion of food or a warm drink, a wave of activity is triggered throughout the digestive system. This is particularly strong after the first food or drink of the day. This wave of peristalsis may bring the stool down to the rectum ready for evacuation. Bowel management should be conducted 20-40 minutes following ingestion of a drink or meal.
Abdominal massage This is thought to stimulate the colon to push the stool along toward the rectum and has been recommended for constipation of various aetiologies (Emly et al, 1998; Richards, 1998; Spinal Cord Medicine Consortium, 1998; Guttmann, 1976). The abdomen is massaged gently using a half closed fist or the heel of the hand in a kneading action, or by using a tennis ball (or similar object) in a rolling motion for 10 minutes. The massage follows the lie of the colon towards the rectum - up the right-hand side of the abdomen, across the abdomen at around the level of the umbilicus, and down the left-hand side of the abdomen. It can be used before and after suppository insertion, and before and between ano-rectal stimulations, or to assist manual evacuation.
Oral laxatives These are not essential for all people with SCI and should not be seen as an inevitable part of bowel management. Many laxatives have undesirable side-effects such as nausea, loose stools, abdominal cramps, wind, dehydration, and electrolyte imbalance.
Patients may become tolerant to laxatives over time. Long-term use of stimulant laxatives is thought to lead to an atonic colon, though sound evidence for this is scant. Evidence to support the choice and dosage of laxatives for people after SCI is lacking.
The right laxative, dose and timing will vary and is usually established through some degree of trial and error. The laxatives most commonly used by this patient group are listed in Box 3.
Removal of stool from lower bowel and rectum
Posture If possible the patient should sit on a toilet, commode or shower chair with a padded seat to evacuate the bowel. The hips and knees should be flexed and the feet supported. Peristaltic activity is greater when sitting up. The weight of the stool can facilitate relaxation of the pelvic floor in those with upper motor neurone bowel function and gravity can assist with the expulsion of stool from the rectum.
Deciding whether to manage the patient in this way will depend on her or his ability to maintain the posture safely, her or his balance, degree of spasticity, and physical assistance required. Access to the toilet for independent or assisted transfer should also be considered.
Time spent sitting on the toilet must be considered and steps taken to prevent pressure ulcers and haemorrhoids. A padded or inflatable seat must be used.
Massage As discussed above.
Ano-rectal stimulation This technique is used to trigger reflex relaxation of the anal sphincters and to stimulate peristalsis in the rectum in patients with a reflex or upper motor neurone bowel.
A gloved, lubricated finger is inserted 2-4cm inside the anal canal and circled gently against the anal wall and lower rectum for 20-30 seconds. The finger should remain in contact with the wall of the rectum. Stimulation should not be continued for more than one minute. The finger should then be removed to allow reflex contractions to move the stool down into the rectum and to push the stool out. The stimulation can be repeated every 5-10 minutes, up to three times until the bowel has emptied and no more stool is felt in the rectum. If stool remains in the bowel after three attempts, manual evacuation should be used to empty the rectum of remaining stool.
Raising intra-abdominal pressure This also raises the pressure inside the rectum, helping to stimulate reflex emptying and to push stool out. This can be achieved by the patient leaning forwards and compressing the abdomen, extending her or his arms to lift the bottom off the toilet seat, or by straining (Valsalva manoeuvre).
This method should be treated with caution. Prolonged straining is associated with the formation of haemorrhoids and may lead to rectal prolapse or pelvic floor damage in the long term. The bladder should be emptied before using this method to avoid vesico-ureteric reflux (an abnormal back-flow of urine from the bladder to the ureters).
Manual (or digital) evacuation of stool The use of a gloved, lubricated finger to remove stool from the rectum is a vital and acceptable part of bowel management for some people after SCI (Addison and Smith, 2000). People with a lower motor neurone bowel have no residual reflex activity that can be stimulated by ano-rectal stimulation, suppositories or enemata. If massage and brief, gentle straining are ineffective, manual evacuation is the only way to remove stool from the rectum.
In people with an upper motor neurone bowel, remaining reflex activity may be insufficient to completely empty the rectum. To avoid episodes of faecal incontinence, manual evacuation should be used to remove any remaining stool.
Suppositories These include the following:
- Glycerin These lubricate the stool and rectum. They also irritate the rectal lining so stimulating reflex bowel activity in those with thoracic or cervical injuries. In individuals with flaccid bowel function they will not stimulate bowel activity and are of use only where stool is hard, dry and difficult to expel or remove;
- Carbalax This contains sodium bicarbonate which causes carbon dioxide to be released when the suppository comes into contact with moisture in the rectum. This in turn causes the intestinal muscles to contract aiding evacuation. Bowel action will usually take place within half an hour of administration. This suppository is only of benefit where reflex bowel function remains and can be irritant to the rectal mucosa;
- Bisacodyl This acts on nerve endings in the walls of the intestine and the rectum. It causes the muscles in the intestine to contract more often with increased force. The suppository produces an effect in about 30-60 minutes but may continue to act beyond the duration of planned care, leading to incontinence. It may also cause irritation of the rectal mucosa and the skin around the anus.
Enemas Micro-enemas deliver a concentrated dose of stimulant laxative directly to the rectal mucosa in the same way as bisacodyl suppositories. Large volume enemas, for example phosphate enemas, are not recommended as the long nozzle can damage the insensitive bowel and the introduction of a large volume of fluid can provoke autonomic dysreflexia in those with injuries above T6. Patients with flaccid bowel function will not be able to retain the fluid of a large-volume enema.
Providing personalised care
An individual assessment must address the factors discussed above. Care is planned with the patient if possible, though in the very early stages after injury the patient may not be able to fully participate in this process.
The interventions required for bowel management must be explained to the patient, and consent and cooperation obtained each time bowel care is given.
The outcomes of the bowel care should be evaluated against simple, relevant measures:
- Were the bowels opened as planned?
- What was the stool consistency? This can be recorded objectively with the Bristol scale (Heaton et al, 1992);
- How long did the bowel management process take?
- Are episodes of faecal incontinence occurring between bowel management episodes?
Depending on the outcomes of the planned care, changes can be made to the bowel management programme until a satisfactory routine is established.
Bowel management in acute SCI
Bowel sounds are monitored four-hourly during spinal shock. When they are detected, the patient can begin oral fluids if this is not contraindicated for other reasons. If oral fluids are tolerated the patient can gradually progress to a light oral diet.
As the patient begins to take nutrition orally, steps need to be taken to begin bowel management. It is imperative that active bowel management is instigated from this early stage following injury to avoid constipation, impaction and over-distension of the colon. It also begins to establish a regular routine.
Glycerin suppositories are often used initially, as they help to lubricate and soften any constipated stool present in the rectum, along with abdominal massage. Oral stimulant laxatives may be needed in the early stages to overcome the effects of immobility and poor oral intake.
Bowel management will initially be conducted daily and the frequency will then depend on the result of management in terms of stool consistency and volume, and continence between interventions. Bowel management is conducted at the same time of day to assist in the development of a pattern.
Even at this early stage, the patient should be involved as much as possible in her or his bowel care.
Rehabilitation and bowel management
During rehabilitation the nurse and patient work together to devise an individualised programme that will provide effective managed continence and promote the reintegration of the individual into her or his home life and community. The use of laxatives is minimised and the essential physical interventions are identified.
The patient progresses along a continuum from dependency on nurses to physical and verbal independence. Skills and knowledge are acquired along the way, including an understanding of their own bowel function after SCI, how to care for themselves, and how to adapt to changing needs after discharge and in the future.
The aim is for physically dependent patients to be verbally independent by discharge. The patient must be able to explain to a carer how to conduct bowel care, as the person with SCI will often be the ‘expert patient’ when outside a specialist unit.
Where possible, professional and lay carers are taught alongside the injured person for whom they will provide care. During rehabilitation adaptations and equipment required to promote the person’s independence in bowel care should be identified.
There is evidence to suggest that bowel management difficulties increase in the long term and pose significant problems for people with SCI, including prolonged evacuation, constipation, pain, haemorrhoids, fissures, and autonomic dysreflexia (Harari et al, 1997; Glickman and Kamm, 1996).
Following SCI, patients will require active management of their bowel function throughout their life. Effective bowel management is fundamental to quality of life after SCI and is supported by education and empowerment of the individual and her or his carers.