Older people often need pain relief yet age related changes can influence drug pharmacokinetics. An awareness of both drug and non-drug interventions is vital
Jasmina Banicek, BSc, RGN, is clinical nurse specialist acute pain management, Whittington Hospital Trust.
Banicek J (2010) How to ensure acute pain in older people is appropriately assessed and managed. Nursing Times; 106: 29, early online publication.
The increasing ageing population, and the common occurrence of acute and chronic pain in this group, means nurses are likely to come into contact with many older patients who need effective pain management. This article examines the assessment of acute pain in older people, as well as different approaches to and challenges in pain management.
Keywords Acute pain management, Older people, Pain assessment
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- Adequate pain relief is necessary to avoid further medical complications.
- Appropriate pain assessment is an essential part of pain management.
- Consider multimodal analgesia but also use non pharmacological techniques.
- Analgesia in older patients must be prescribed and administered with caution due to increased risk of side effects.
Pain management is likely to become an increasingly important issue given the expected rise in the number of older people.
In 2005 over 11 million people in the UK were of pensionable age, with this number expected to rise to 15.3 million by 2031 (Age Concern, 2007). Pain is a common problem for older people as they may suffer from long term painful conditions such as osteoarthritis, degenerative joints, leg ulcers and many others.
Pain is under recognised and under treated in the older population. Some authors suggest that altered physiology of peripheral and central pain mechanisms, combined with psychological attitudes such as stoicism and reluctance to report pain, are key factors in this (Schofield, 2007).
Why treat pain?
The body responds to pain in many adverse ways (Box 1).This means accurate pain assessment and management is vital for high quality patient care.
Box 1. Physical responses to pain
- Respiratory: if a patient is unable to cough or take deep breaths due to pain, their recovery rate is significantly reduced. They also have an increased risk of developing chest infection, hypoxia and possible respiratory failure.
- Cardiovascular: the increased sympathetic chain activity in response to pain causes an increase in hormonal activity, which in turn produces an increase in blood pressure. Tachycardia also occurs, and this can lead to a degree of myocardial ischaemia, especially in people with pre-existing cardiovascular disease. Those who are reluctant or unable to mobilise due to pain are at increased risk of developing deep vein thrombosis and/or pressure sores.
- Gastrointestinal: pain can lead to delayed gastric emptying and reduced intestinal motility. This can result in nausea, vomiting and constipation.
- Endocrine: pain leads to the “stress response” caused by a release of a number of hormones. For example, release of cortisol causes hyperglycaemia, which can lead to immunosuppression and delayed wound healing.
- Psychological: pain can lead to anxiety, depression, worry, sleep deprivation and mistrust of healthcare professionals.
The assessment of pain is an essential prerequisite for achieving effective pain management, and there are various valid and reliable pain assessment tools. In adults, the three most commonly used methods are:
- The visual analogue scale (VAS);
- The verbal numerical rating scale (VNRS);
- The categorical rating scale.
The VAS uses a 10cm scale, with “no pain” at one end and “worst pain” at the other. Patients mark on the scale the point that best represents their pain (Fig 1). This method can be confusing, especially for older people who may have visual impairment.
The VNRS is similar to VAS. Patients are asked to give a number that best represents their pain on a scale between 0 (no pain) and 10 (worst pain) (Fig 2). They may still have difficulty rating their pain as a number.
The categorical rating scale uses different words – such as “none”, “mild”, “moderate”, “severe” – to rate pain. This can be used in combination with VNRS. For example, patients can be asked to describe their pain as “none (0)”, “mild (1)”, “moderate (2)” or “severe (3)”.
It is important to note that severity is only one aspect of pain assessment. Box 2 outlines SOCRATES, a pain assessment framework commonly used by healthcare professionals that uses a range of different factors.
Box 2. SOCRATES pain assessment framework
S – severity: none, mild, moderate, severe
O – onset: when and how did it start?
C – characteristic: is it shooting, burning, aching – ask the patient to describe it
R – radiation: does it radiate anywhere else?
A – additional factors: what makes it better?
T – time: is it there all the time, is there a time of day when it is worse?
E – exacerbating factors: what makes it worse?
S – site: where is the pain?
People with cognitive impairment or dementia
Those with dementia or with more than mild cognitive impairment may find it difficult to articulate their pain.
Barriers to effective pain assessment with these groups include lack of recognition of pain, lack of appropriate assessment tools, lack of education and training, and misdiagnosis or late diagnosis (McAuliffe et al, 2009).
Several strategies have been suggested to address these issues:
- Getting to know the person;
- Involving friends, family members and carers;
- Education and training;
- Use of adequate assessment tools (McAuliffe et al, 2009).
When working with people with dementia and cognitive impairment, nurses also need to make an observational assessment of pain behaviour. Tools such as the Abbey Pain Scale (Abbey et al, 2004) and Pain Assessment in Advanced Dementia (PAINAD) help practitioners assess pain by observing behavioural indicators such as:
- Facial expressions (frowning, grimacing);
- Vocalisation (crying, groaning);
- Change in body language (rocking, guarding);
- Behavioural change (refusing to eat, alteration in usual patterns);
- Physiological change (blood pressure, heart rate);
- Physical change (skin tears, pressure areas).
Kaasalainen et al (2007) highlighted the importance of appropriate pain assessment in older people and difficulties in choosing drug treatment. A common misconception is that patients who do not complain about pain have no pain (Pasero et al, 1999). There is also fear of prescribing opioids because of side effects.
Pharmacological treatments are not without risks, and awareness of the age related changes that can influence drug pharmacokinetics is paramount. Drug absorption, distribution, metabolism and excretion can all change as a result of ageing. Age related changes apply specifically to body composition, adipose tissue distribution, and water and muscle volumes. Evidence suggests that sensory neurones decrease in number and sensitivity (Schofield and Simpson, 2009). Listening to patients’ perspective and respecting their decisions is vital for achieving optimal concordance.
In line with the long established World Health Organization (1990) analgesic ladder, the usual pharmacological process for pain management is to begin with mild analgesics, such as paracetamol. If the pain is still not adequately managed, the next step is to add non-steroidal anti-inflammatory drugs (NSAIDs), before progressing to mild opioids such as dihydrocodeine, codeine or tramadol. If the pain is still moderate to severe, the next step is to introduce stronger opioids such as morphine and fentanyl.
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Paracetamol is simple and effective and has minimal side effects. Its significant advantage is the lack of stomach irritation; it is therefore the non-opioid analgesic of choice, particularly for treating older people. Its main disadvantage is that overdosage is dangerous as it may cause hepatic damage; sometimes this does not become apparent for 4-6 days (Waterfield, 2008).
The mechanism of action of paracetamol is not completely understood, but it is believed to reduce pain by interrupting or suppressing pain signals along the nerves. Paracetamol has no significant action on COX-1 and COX-2 enzymes, which explains its lack of anti-inflammatory action and the lack of gastrointestinal (GI) side effects (Waterfield, 2008).
Paracetamol can be combined with some weak opioids such as codeine (8mg, 15mg, 30mg) known as co-codamol, or dihydrocodeine (10mg, 20mg, 30mg) known as co-dydramol.
The British National Formulary notes that compound preparations are less suitable in general as they increase the risk of overdosage. It also states that adding the low dose of opioid may be enough to cause side effects without providing significant pain relief (BNF, 2010).
Paracetamol is available in a wide range of preparations, such as caplets, tablets, solutions and dispersible tablets. It is important to check which preparation patients prefer, as some may not take their paracetamol because tablets are too big or they do not like the taste of dispersible solution.
Many over the counter products, such as cold and pain relief preparations, contain paracetamol. It is therefore important to take a full medication history to avoid duplication and potentially serious overdose.
Non-steroidal anti-inflammatory drugs
NSAIDs are a large group of drugs used to treat pain and inflammation. Common examples include ibuprofen, diclofenac and naproxen. NSAIDs inhibit the formation of prostaglandin, which is responsible for modulating inflammation. Prostaglandin also reduces acid production, and increases mucus in the stomach and blood flow to the kidneys. Some of the side effects of NSAIDs therefore include peptic ulceration and salt and water retention. When prostaglandin is inhibited by NSAIDs, less blood reaches the tubules in the kidneys; conditions such as chronic heart failure, hypertension and renal disease are exacerbated (Waterfield, 2008).
A single dose has analgesic activity similar to that of paracetamol. In regular full dosage NSAIDs have a lasting analgesic effect and an anti-inflammatory effect. The full effect may not be achieved for up to three weeks. This is particularly significant for prescribers when managing patients’ expectations about pain relief (Waterfield, 2008). It should be noted that topical application of large amounts of topical NSAIDs may result in systemic effects including hypersensitivity and asthma. The interaction section of the BNF (2010) states that interactions of NSAIDs do not generally apply to topical formulations.
Naturally occurring opium based substances such as the alkaloid morphine are called opiates, while all drugs that act on opioid receptors, natural or synthetic, are called opioids. These receptors are found in the brain, spinal cord and some in the peripheral nerve endings.
Opioid drugs are classified according to their action:
- Agonists, such as morphine and fentanyl, bind to and stimulate an opioid receptor and are capable of producing a maximal response from the receptor;
- Partial agonists, such as buprenorphine, stimulate opioid receptors but have a ceiling effect, that is, they produce a submaximal response compared with an agonist;
- Agonist-antagonists, such as pentazocine, act as agonist at one type of receptor and antagonist at another;
- Antagonists, such as naloxone, bind to but do not stimulate the opioid receptor and may reverse the effect of opioid agonists.
Once the drug has bound to the receptor, the function of the cell is changed. This may alter neurotransmission and therefore action potential. Strong opioids such as morphine exert a strong change within the cell, while the weak opioids such as codeine act on the receptors to a lesser extent.
Commonly used weak opioids are codeine, dihydrocodeine and tramadol and are used for moderate to severe pain. Strong opioids such as morphine, fentanyl, diamorphine and oxycodone are used to treat severe pain and can be administered in different ways (Box 3).
Box 3. Administration of strong opioids
- Oral (PO): this is a preferred route for patients who are able to eat and drink. Doses need to be larger than when given by other routes.
- Intravenous (IV) including patient controlled analgesia (PCA): this is the quickest route, and 100% of the drug is available. Small boluses can be titrated according to patients’ pain, producing a more constant level of drug. PCA allows patients to administer a small amount (bolus) of an opioid via the specifically pre-set pump. This system has a lockout time (usually five minutes), so patients have to wait until the next dose is available. This prevents them from continuously receiving opioids and potentially overdosing.
- Subcutaneous (SC); not fentanyl: a small butterfly needle may be inserted into the subcutaneous tissue and regular injections can be given through the injection port. May be suitable for those with poor venous access.
- Transdermal; fentanyl and buprenorphine only: the opioid is administered in a patch form. Onset of action usually takes 12–24 hours.
- Sub-mucosal: oral, nasal or pulmonary routes include intranasal diamorphine and fentanyl lozenges.
- Epidural/spinal (intrathecal): this method is used for intra- and postoperative analgesia.
- Rectal (PR); morphine only: this is not a common route to administer opioids but may be necessary if all other routes are inaccessible.
Limitations of opioid use
The side effects associated with opioids limit their use and sometimes lead patients to stop treatment despite benefiting from pain relief. Dizziness, nausea and constipation are all common, while constipation can be the most problematic and can cause abdominal cramping, bloating, nausea and vomiting. For many patients, constipation can have a profound negative impact on quality of life.
Before starting opioid treatment, prescribers should always warn patients about side effects, provide dietary advice and suggest remedies to prevent constipation, such as laxatives. However, many patients who benefit from pain relief but suffer from constipation wonder whether to continue taking opioids or stop the treatment and go back to milder, less effective analgesics. Prescribers should therefore weigh up the risks and benefits with patients, and they may need to accept that some patients prefer to be in pain rather than experience unpleasant side effects.
Other medications and considerations
Other medications, used primarily in chronic pain, change the way in which messages are sent along the nerves, or how they are processed by the brain and spinal cord. These include some antidepressants such as amitriptyline and some anti-epileptic medicines such as gabapentin.
It is important to consider different ways of delivering appropriate medication. NSAIDs can be given as gels, and opioids can be administered as skin patches. People with constant pain generally find it easier to manage modified release formulations such as MST Continus.
Challenges with medication
Analgesia must be prescribed for older people with caution because there is a high incidence of sensitivity to medication such as NSAIDs, which increase the risk of GI bleeding.
Although ageing is associated with increased gastric pH and delayed gastric emptying, there is little evidence to suggest that intestinal drug absorption changes with age (Reid et al, 2001). Age related changes in body composition, protein binding and organ blood flow can affect drug distribution. A relative increase in adipose tissue and corresponding bodily water reduction also affects the volume of distribution. The volume of distribution of water soluble drugs is smaller, and this causes an increase in initial drug concentration. Lipid soluble drugs tend to have an increased volume of distribution, which prolongs the elimination half life (Reid et al, 2001).
There is evidence for age related changes in the rates of metabolism of some drugs (Reid et al, 2001). For example, drugs that undergo oxidation are likely to be metabolised more slowly. Also, older people have reduced first pass metabolism. Drugs that undergo extensive first pass metabolism may therefore show considerably increased bioavailability (Reid et al, 2001), and reduced doses may be indicated in older people. Overall, this effect is amplified by the presence of liver disease.
Renal blood flow and renal function decrease in older people. The glomerular filtration rate (GFR) falls by approximately 30% by the age of 65. Some drugs that are excreted mainly by glomerular filtration will therefore accumulate and their dose should be reduced (BNF, 2010). Moreover, older people are potentially more likely to suffer renal tract disease, which reduces drug clearance.
It is highly likely that older patients are already on a number of different medications. Multiple drugs (polypharmacy) can lead to an increased risk of side effects as well as reduced compliance. Older patients are more likely to develop adverse reactions to different types of analgesic drugs at much lower doses (Popp and Portenoy, 1996).
Adverse drug reactions
A significant adverse drug reaction (ADR) is experienced by around one third of older patients taking multiple medications (Hanlon et al, 1997). ADRs are unpleasant, can lead to hospital admissions and, in exceptional cases, reactions may be fatal (Pirmohamed et al, 2004).
Certain long term conditions that are common in older people– such as hypertension, ischaemic heart disease and chronic obstructive pulmonary disease – require multiple medications. In these circumstances the chance of an ADR is relatively high, and the risk rises with an increased number of medications.
Drug interactions may increase or decrease the activity of one or more drugs. Drugs may interact by enhancing or blocking activity at a specific binding site (receptor or ion channel or transporter molecule or enzyme) (Morris, 2008). For example, a patient with asthma taking an inhaled beta-2 agonist such as salbutamol may find this less effective if also taking a beta blocker such as atenolol. Beta blockers are therefore contraindicated in asthma and alternative therapy should be sought (McGavock, 2002a). When prescribing a new drug, check BNF appendix 1 for possible interactions.
The key sites of drug metabolism and elimination are the liver and kidneys, and people with impaired liver and/or kidney function are at greatest risk of an ADR from high drug concentration (due to accumulation).
Types and causes of ADRs
ADRs can be classified into two types: type A and type B. Type A reactions are often predictable depending on the mode of action of the drug and are more likely to occur at higher dosage (Courtney and Griffiths, 2008). For example, NSAIDs can cause dyspepsia; opiates cause constipation. These common examples of ADRs can be avoided by either stopping or reducing the drug dosage or, if necessary, by using an alternative drug (McGavock, 2002b).
An adverse reaction may also occur following sudden cessation of a drug, causing withdrawal symptoms. For example, antidepressants and benzodiazepines should be slowly reduced before completely stopping.
Type B ADRs are idiosyncratic in nature, not predictable and unrelated to the drug dose. An example is an anaphylactic reaction to penicillin.
Many drugs, such as NSAIDs, should be used with caution when treating older patients. Diuretics are often poorly tolerated by older people, and electrolyte disturbances are common (Morris, 2008). Drugs with a narrow therapeutic window, such as warfarin and digoxin, are particularly likely to cause problems for older patients. Regular measurements of drug levels should be undertaken.
Reporting and avoiding ADRs
Suspected adverse reactions should be reported to the Medicines and Healthcare products Regulatory Agency (MHRA), using the yellow card that can be found at the back of the BNF or MIMS or online (http://yellowcard.mhra.gov.uk). The “black triangle” symbol identifies newer drugs that are still closely monitored, and all ADRs involving these drugs should be reported through the yellow card system.
Before starting a new drug, it is important to consider carefully whether there are safer options for older patients. Detailed history taking – including current drug regimen, over the counter drugs and herbal treatments – is imperative before prescribing.
- Always choose the lowest effective dose of the drug to be used for the shortest possible time;
- Start with a lower initial dose and gradually increase if necessary;
- Take into account renal and liver function;
- Liaise with other prescribers, for example GPs, and provide adequate information to patients and carers.
All these measures can help to prevent potential errors, polypharmacy and serious ADRs. It is important that older patients have regular medication reviews (Morris, 2008).
Growing evidence supports the use of non-pharmacological interventions for treating pain. These can include cognitive behavioural techniques, physical methods and complementary therapies (Carr and Mann, 2000).
Behavioural interventions may look at altering certain behaviours to reduce the perception of pain. Cognitive interventions are defined as methods which alter negative thinking styles related to anxiety about a painful situation. This may be by using coping strategies to manage pain. Examples of these techniques include distraction and dissociation (Carr and Mann, 2000), using music, reading, watching television or talking about pleasant subjects. Relaxation techniques can also help patients achieve a state of relative freedom from anxiety and muscle tension, a quieting or calming of the mind and muscles. These techniques can be taught; however, it may difficult to do this on a busy hospital ward.
Physical intervention methods and complementary therapies to help manage pain include:
- Exercise and mobilisation;
- Correct positioning;
- Application of hot or cold;
- Trans-electrical nerve stimulation (TENS);
- Physiotherapy (Flor and Turk, 2006; Gifford et al, 2006).
To become effective practitioners, we need to overcome real or perceived barriers to good pain management. These include:
- Beliefs among doctors and other professionals that pain management is not important;
- Poor assessment techniques and the lack of appropriate tools;
- Inadequate dissemination of available knowledge;
- Fear of addiction, tolerance and adverse effects.
Effective individual care plans encourage patients to report their pain freely and take into account each person’s willingness to take medication or not. Careful assessment and the use of appropriate tools will go a long way towards improving the quality of older patient care.
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