Pain management: assessment and diagnosis
VOL: 98, ISSUE: 39, PAGE NO: 43
SHARON WOOD, MSc Pain Management, Dip Healthcare Research, RGN, IHBC Body Massage, is lecturer in nursing, University of Leeds
Sponsored by Pfizer
All healthcare professionals have a humanitarian, moral and ethical responsibility to manage and relieve patients’ pain. ‘By any reasonable code, freedom from pain should be a basic human right, limited only by our knowledge to achieve it (Royal College of Surgeons and Anaesthetists, 1990). On this basis, healthcare professionals require the knowledge and skills to be able to investigate, diagnose and assess patients’ pain and, although there have been, and continue to be, major advances in the management of pain, patients’ pain continues to be under-treated.
Investigations and diagnosis
If healthcare professionals are to render an accurate diagnosis, it is essential that they are able to describe a patient’s symptoms accurately, aided by the use of diagnostic machines and techniques where appropriate or possible (Sullivan and Spertus, 2001).
There are numerous definitions of pain that may assist the healthcare professional in reaching a diagnosis. Two of these were highlighted in Part 1. The assessment and measurement of pain also play a crucial role in investigating and diagnosing pain, although there are many factors involved in this process that influence the information that is elicited from patients (Box 1).
For those in clinical practice, there are a number of guidelines available for investigating, diagnosing and managing pain. For instance, the Agency for Health Care Policy and Research (1992) recommends guidelines for acute pain management; the Clinical Standards Advisory Group’s Report on Back Pain (CSAG, 1994) gives recommendations on the biopsychosocial assessment and management of acute back pain, and the World Health Organization recommends clinical practice guidelines for cancer pain relief (WHO, 1990).
Recommendations for the type of intervention for a diagnosis of acute pain are usually simple and rapidly determined (International Association for the Study of Pain, 1992), but this is not usually the case with chronic pain, as the processes of investigation, diagnosis and management for this type of pain are often more complex and may take some time.
Obtaining an accurate estimation of a patient’s pain is crucial to its assessment and management. A systematic process of assessment and measurement will enhance a healthcare professional’s ability to achieve increased comfort, pain relief and improved function for the patient. Pain assessment involves an overall appraisal of the plethora of factors that have an effect on the pain experience (McCaffery and Pasero, 1999) (Box 1). Moreover, the assessment and measurement of pain in specific groups of patients, for example, visually impaired patients and children, requires additional considerations (Turk and Melzack, 1992).
Think Point: What different factors would you need to consider when assessing and measuring:
1. A child’s acute postoperative pain?
2. The chronic arthritis pain of an older person?
Measuring pain allows the health professional to assess the degree of a patient’s pain. A patient’s self-report of his/her pain provides the most valid measurement of the experience (Melzack and Katz, 1994). Uni-dimensional tools measure one dimension of the pain experience, for example, its intensity. These are accurate, simple, quick, easy to use and understand, and are commonly used for acute and postoperative pain assessment. Multidimensional pain assessment tools are also available (Box 2). Verbal rating scales are commonly used for postoperative pain assessment (Fig 1).
Multidimensional pain tools provide information about the qualitative and quantitative aspects of pain. Completion of these tools requires good verbal skills and sustained concentration, as they take longer to complete than uni-dimensional tools. The McGill pain questionnaire is commonly used for chronic pain assessment (Turk and Melzack, 1992).
To facilitate documentation and accountability of pain management (Dimond, 2002), it has recently been recommended that pain becomes the ‘fifth vital sign’.
Treatments and side-effects
Pharmacological management of pain
Two categories of drugs are used for the treatment of pain - non-opioids and opioids.
Included in this category are paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, diclofenac, ketorolac, piroxicam, naproxen. The mechanism of action of paracetamol is unclear, although it appears to have some action on the central nervous system. NSAIDs exert their main effect through their inhibitory action on prostaglandins in the peripheral nervous system, but they also have an effect on the central nervous system. There are a number of routes of administration, cautions, contraindications and side-effects associated with NSAIDs (McQuay and Moore, 2002; British National Formulary, 2002) (Box 3).
Opioids are divided into three categories: morphine and its derivatives, such as morphine, fentanyl, codeine, oxycodone, hydromorphone; agonist-antagonists such as pentazocine and nalbuphine, and partial agonists, such as buprenorphine (British National Formulary, 2002). Opioids exert their main effect through their binding effect on opioid receptors in the brain and spinal cord, although it has been suggested that they have an effect on the peripheral nervous system (Twillman et al., 1999).
As with non-opioids, there are a number of routes of administration of opioids, cautions, contraindications and side-effects (Box 3) (McQuay and Moore, 2002; British National Formulary, 2002). The administration of morphine by means of patient-controlled analgesia as opposed to intramuscular injection reduces the incidence of pain and side-effects and makes patients feel more positive about their postoperative pain management (Chumbley et al., 1999).
Many patients require more than one analgesic for the management of their pain. Effective relief for acute pain can be achieved with oral non-opioids and NSAIDs, while in incidences of severe acute pain an opioid is recommended as first-line treatment with the addition of other methods as appropriate, for example, nerve blocks and psychological care. Acute pain can be managed effectively with appropriate drug doses, routes and methods, and many hospitals now use a strategy for acute pain management (Fig 2) (McQuay and Moore, 2002) similar to that shown in the WHO analgesic ladder (Fig 3).
Patients with chronic pain can be managed with non-opioids, NSAIDs and opioids, as in acute pain, but if these are ineffective or have intolerable side-effects, other methods should be considered, such as unconventional analgesics, nerve blocks, psychological and behavioural treatment (McQuay and Moore, 2002). The management of cancer pain can be effectively relieved in the majority of cases using analgesics according to the WHO analgesic ladder.
Unconventional or adjuvant analgesics
Although this group of drugs has a primary function other than for relief of pain they are also used as analgesics in some painful conditions. Examples are antidepressants (amitriptyline), anticonvulsants (gabapentin), corticosteroids (dexamethasone), oral local anaesthetics (mexilitine), and skeletal muscle relaxants (baclofen). Others are ketamine, capsaicin and clonidine (British National Formulary, 2002). The exact mechanisms for the analgesic actions of all these drugs have not been fully identified. Some studies (McQuay and Moore, 2002) have shown that they act on nerve conduction channels and on various neurotransmitters and neuroreceptors within the peripheral and central nervous systems, thereby inhibiting the transmission of pain impulses and producing analgesia. There are a number of routes of administration, cautions, contraindications and side-effects associated with these groups of drugs (British National Formulary, 2002).
Nerve blocks (regional analgesia) can deliver pain relief by interrupting pain transmission over a localised area, thereby reducing the side-effects from systemically administered drugs. Different drugs and different types of nerve blocks are used for acute and chronic pain management and these have different risks associated with them (McQuay and Moore, 2002).
Non-pharmacological management of pain
Non-pharmacological strategies (Box 4) are not intended to replace pharmacological interventions; rather, they are adjuncts which may improve overall pain management (Zaza et al., 1999). There is currently a lack of rigorous scientific evidence to support many of the strategies, especially in acute pain management (McQuay and Moore, 2002).
Non-pharmacological methods of pain relief achieve their effects in numerous ways, not only in reducing the intensity of the pain but also by reducing the emotional components, so reducing anxiety, facilitating coping skills, providing a sense of control, enhancing comfort, promoting sleep, reducing fatigue and improving quality of life (McCaffery and Pasero, 1999).
There is often more interaction with patients who are being given non-pharmacological treatment than with those being treated by conventional means, resulting, often, in the establishment of empathetic relationships (Frischenschlager and Pucher, 2002).
There may also be some positive physiological effects of such strategies, including, reduced blood pressure, pulse and respiratory rate, muscle relaxation and the possible release of endogenous opioids. Non-pharmacological strategies for pain management also highlight the important contribution that specialists in psychology, psychiatry, physiotherapy and other disciplines can make to pain management (International Association for the Study of Pain, 1992).
Think Point: Describe the different pharma-cological and non-pharmacological inter-ventions that could be used for patients in the following circumstances:
1. After a routine total abdominal hysterectomy.
2. For chronic low-back-pain-associated sciatic pain.
Assessing pain in patients with cognitive impairment has been a problem for many years. A recent research study funded by the Mental Health Foundation - Pain Assessment in Nursing Home Residents with Varying Degrees of Cognitive Impairment - has recently been completed (Closs, 2002 - personal communication). One of the objectives of the study was to identify and develop appropriate verbal and non-verbal pain assessments for use with residents with varying levels of cognitive impairment.
Five different pain assessment scales were presented in random order to 113 nursing home residents. Nursing home staff and relatives of the residents were interviewed about their cues to assess pain.The results showed that the simple four-point verbal rating scale (none, mild, moderate, severe) appeared to be the most successful. There was a tendency for fewer scales to be completed as the level of cognitive impairment increased.
Both staff and relatives inferred pain from a wide variety of cues: vocal, physical, facial and emotional. The study concludes that there was no difference in pain scores according to cognitive status, therefore it would appear important to assess (and treat) pain regardless of the level of a person’s cognitive impairment.
In February this year the government announced that cannabis-based pain relief would be given consideration. Current trials in the UK are assessing the benefits of pain-relieving medicines derived from cannabis (cannabinoids). They are investigating the use of cannabinoids for postoperative, chronic and cancer pain and for pain associated with multiple sclerosis. Results are expected at the end of this year.
Despite the lack of rigorous scientific evidence to support many of the non-pharmacological strategies for pain management, systematic reviews have been conducted on a variety of these strategies. Reviews by the Cochrane Library found that the use of transcutaneous electrical nerve stimulation (TENS) was inconclusive for chronic pain, and that massage was beneficial for low back pain (Cochrane Library, 2002).
There are currently randomised-controlled trials being undertaken to investigate the use of TENS for postoperative and chronic pain, and acupuncture for chronic pain management (National Research Register, 2002). A recently published randomised controlled trial showed that music and relaxation individually, and music and relaxation together, reduced the levels of postoperative pain (Good et al., 2002).
In August 2002, the government announced a major expansion of the number of operations performed as day cases. A recent research study concluded that more support and more information are needed to manage patients’ pain effectively while in day-case wards and also at home following discharge (McHugh and Thoms, 2002). Johanet et al. (2002) concluded that simple procedures are needed to prevent postoperative pain for outpatient surgery. The expansion of day-case surgery, therefore, has implications for pain management during the pre-operative, inter-operative, and postoperative stages. This may involve partnerships between the acute and primary care providers and has major resource implications.
Think Point: Describe the effects that one of your patients has experienced after using one or more non-pharmacological strategies for pain management. There is a lack of a rigorous evidence base to support the use of non-pharmacological strategies for pain management. What implications does this have for your clinical practice?
In order to manage patient’s pain effectively it is imperative that nurses gain knowledge of pain assessment and management. This knowledge should encompass the many factors that affect the experience and assessment of pain and the variety of interventions and strategies that are available to manage it. There are local, national and international guidelines for pain management that can contribute to this process.