Definitions
A widely used definition of pain is:
‘… an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage’.11
This definition does not address the autonomic responses associated with obnoxious stimuli, which is a key feature of pain in the emergency setting. A second definition proposed by Margo McCaffery as long ago as 1968 has become widely used by healthcare professionals. She states that pain is:
‘… whatever the experiencing person says it is, existing whenever the experiencing person says it does’.12
Pain is a complex phenomenon that comprises both physical and emotional elements; it is a subjective experience and should rely heavily on the patient’s self-report whenever possible. A significant problem for the practitioner is related to this subjectivity. Paramedics interviewed by researchers expressed doubts as to the validity of some patients’ pain descriptions, suggesting that patients may feel they need to increase their explanation of pain to be believed and to be taken seriously by the paramedics. Others felt that pain descriptions were exaggerated by patients with minor ailments so that they can justify calling an ambulance, also thinking that they will be seen more promptly at hospital.13 The paramedics also believed that the cultural background of the patient had a major impact on their pain experience. They recognised a cultural difference to exist in the way that pain was expressed, with some cultures thought to be more vocal and emotional in expressing their pain. It was also held that older people may perceive pain differently to younger people and would be less likely to ask for help.13 All of this indicates just how difficult assessment of pain can be, especially acute pain in the emergency setting.
Acute pain v chronic pain
Acute pain
Acute pain has been defined in a number of different ways but a common feature in definitions is that is a symptom with a discernible cause and usually subsides when injured tissues heal. Acute pain has a protective function.
Chronic pain
Chronic pain is, by definition, pain that has persisted beyond the time of healing; a classification based purely on causal agent is not achievable. Some patients become extremely disabled and suffer intractable pain even though their identifiable pathology appears to be relatively mild; other individuals with similar pathologies may report pain but do not present with the same level of disability.14 Good evidence exists to show that quality of life for patients with chronic pain is more associated with beliefs about pain than the severity itself.15 Although emergency care is often associated with acute pain, it is likely that those suffering from chronic pain (e.g., cancer, lower back pain, multiple pain localisations) will also access the emergency services.
The cornerstone of pain management is the assessment of the pain. A variety of pain assessment tools are available to assist in determining the level of pain and evaluating the effectiveness of interventions. These tools should be used in conjunction with a thorough history of the pain to help diagnose the most likely cause of the pain as well as the severity.
Assessing pain
- Look at the patient
- Taking the history of the pain
- Pain assessment tools.
Initial observations
It is worth noting the patient’s position, any guarding of the site of pain and how well they mobilise. Significant information can also be obtained by watching the patient’s face, especially during mobilisation. This is covered later in the chapter as a checklist of non-verbal indicators.
History of the pain
The history is vital to help make a differential diagnosis and several mnemonics have been suggested to help practitioners. Whether or not to use a mnemonic is for the individual practitioner to decide; two different ones will be presented here. It is important to remember that questions are only relevant if the practitioner understands the answers, so it is essential to have a sound understanding of the pathophysiology behind the clinical manifestations.
OPQRST mnemonic
This is probably one of the most commonly taught mnemonics in emergency care although some texts do not mention the ‘O’ element.
What was the patient doing when the pain came on?
Was the patient exercising or exerting themselves?
Was the patient eating or drinking, if so, what?
What palliates the pain (makes it better?)
Were there any precipitating factors e.g., did this come on after exercise?
Are there any associated symptoms – e.g., nausea, vomiting, dizziness?
Table 15.1 CHESTPAIN mnemonic
| C | Commenced when? | When did the pain start? Was onset associated with anything specific? Exertion? Activity? Emotional upset? |
| H | History/risk factors | Do you have a history of heart disease? Is there a primary relative (parent/sibling) with early onset and/or early death related to heart disease? Do you have other risk factors, e.g., diabetes, smoking, hypertension, or obesity? |
| E | Extra symptoms | What else are you feeling with the pain? Are you nervous? Sweating? Is your heart racing? Are you short of breath? Do you feel nauseous? Dizzy? Weak? |
| S | Stays/radiates | Does the pain stay in one place? Does it radiate or go anywhere else in the body? Where? |
| T | Timing | How long does the pain last? How long has this episode lasted? How many minutes? Is the pain continuous or does it come and go? When did it become continuous? |
| P | Place | Where is your pain? Check for point tenderness with palpation. |
| A | Alleviates | What makes the pain better? Rest? Changing position? Deep breathing? |
| Aggravates | What makes the pain worse? Exercise? Deep breathing? Changing positions? | |
| I | Intensity | How intense is the pain? |
| N | Nature | Describe the pain (do not suggest descriptors) |
Adapted from Newberry, Barnett and Ballard (2003).16
A recent mnemonic has been proposed specifically for the evaluation of chest pain (Table 15.1) and incorporates risk factors for cardiac problems. The mnemonic is CHESTPAIN.
Pain assessment tools
The tools that will be covered in this section include:
- Numerical Rating Scale
- Visual Analogue Scale
- Verbal Rating Scale
- Wong–Baker FACES Pain Scale
- Checklist of non-verbal indicators.
Numerical Rating Scale (NRS)
The numerical rating scale is probably the most commonly used tool in prehospital emergency care and generally encompasses an 11 point scale ranging from 0 (no pain) to 10 (worst pain). It is simple to administer and requires no specific equipment. The NRS is often administered verbally in the prehospital setting but it could easily be completed as a paper exercise (see Figure 15.1), which may be helpful to those patients who have difficulty in allocating a pain score verbally. A study showed the NRS to have poor reproducibility17 and highlighted the importance of consistency of terminology to ensure that confusion does not arise. A study in the emergency department has shown a verbally administered NRS to be a suitable substitute for the VAS, see below in the assessment of acute pain.18
| Procedure | Additional information/rationale |
| 1. Establish that the patient is able to use numbers to quantify their pain. | Improves likelihood of answers being accurate. |
| 2. Explain the parameters of the scale and use descriptors at each end of the scale. | Patient needs to know which end of the scale represents severe pain for accuracy of measurement. |
| 3. Ask the patient one of the following questions: • What number would you give your pain right now? • What number on a 0 to 10 scale would you give your pain when it is the worst that it gets and when it is the best that it gets? • At what number is the pain at an acceptable level for you? | |
| 4. Record pain score and repeat at frequent intervals. | Allows evaluation of effectiveness of pain management strategies and whether more needs to be done. |
| 5. For written NRS, follow the above but ask patient to circle the number that describes how much pain they are having. |
Figure 15.1 Numerical Rating Scale.
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