Assessment of Acute Pain

   Accurate assessment of acute pain is essential for the development of an effective pain management plan. Nurses play a pivotal role in the assessment of pain, owing to the nature of their relationship with patients. Pain assessment can be challenging because of the subjectivity and multidimensionality of the pain experience. The patient's self-report of pain includes the sensory, emotional, psychological, and cultural components of the pain experience, which cannot be captured on the unidimensional tools typically used in practice. A comprehensive pain assessment includes pain location and quality, aggravating and alleviating factors, timing and duration, pain relief and functional goals, and intensity. The effectiveness of any previous pain treatment, as well as the effects of pain on quality of life, should also be determined.

   The comprehensive pain assessment should be performed when patients present with pain to the healthcare setting and at the onset of new acute pain. To determine treatment effectiveness and guide further interventions, subsequent pain assessments should focus on the nature of the pain, pain intensity, and responses to treatment. Pain assessment tools should be valid and reliable for the patient population in which they are used.

Unidimensional pain intensity scales.

   Unidimensional scales are quick and easy to use, provide rapid feedback about the effectiveness of interventions, and are valid and reliable measures of pain intensity. Because the unidimensional scales measure only intensity, they cannot substitute for a comprehensive pain assessment. The unidimensional pain intensity scales used most often in the clinical setting are:

- Numeric Rating Scale (NRS), also known as the Numerical Pain Intensity Scale (NPI);
- Visual Analog Scale (VAS); and
- Verbal Descriptor Scale (VDS).

Numeric Rating Scale.

   The NRS can be used graphically (visually) or verbally. When used graphically, the NRS consists of a vertical or horizontal line that is anchored by the number 0 on the bottom or the left side and the number 10 on the top or the right side. Patients are instructed to rate the intensity of their pain on this scale, with "0" indicating no pain, and "10" indicating the worst pain imaginable.

Visual Analog Scale.

   The VAS is a 10-cm (100-mm) line on which the patient is asked to place a mark that corresponds with his or her current pain intensity. The line is then measured from the beginning to the patient's mark, and this distance is translated into a pain intensity score ranging from 0 to 10. The format of scale, coupled with the need for a marking implement and for the patient to be able to clearly visualize and mark the line, make the VAS impractical to use in the clinical setting.

Verbal Descriptor Scale.

   The VDS uses the verbal descriptors "no pain," "mild pain," "moderate pain," "severe pain," "very severe pain," and "worst pain possible." This scale can be administered verbally or visually, and the patient is instructed to pick the words that best describe his or her current pain intensity.

Pain assessment in older adults.

   Older adults deserve special consideration in a discussion of pain assessment. As the number of older adults in society increases, it is important to understand the effect of pain on this population and determine the appropriate assessment and management techniques. Older adults with mild to moderate cognitive impairment can self-report pain. Many unidimensional pain tools have been tested in older adults, and several of these tools, including the NRS, have been validated for use in this population. In addition to the NRS, the Faces Pain Scale-Revised (FPS-R) and the Iowa Pain Thermometer (IPT) have been validated for use with older adults. When compared with other commonly used pain intensity scales (NRS, VAS, VDS, and FPS-R), the IPT was the scale most preferred by both younger and older adults, supporting findings that older adults prefer scales with verbal descriptors.

Hierarchy of Importance of Pain Measures

   In many situations, particularly in the acute care setting, it is not possible to obtain a patient self-report of pain intensity. Patients who are critically ill, sedated, confused, delirious, or otherwise cognitively impaired may be unable to report pain. The assessment of pain in this population is challenging because no single objective strategy, such as observation of behaviors or vital signs, provides sufficient information to assess pain. Nurses often rely on heart rate, respiratory rate, blood pressure, and other physiologic data to confirm the presence of pain; however, these variables are the least sensitive indicators of pain and may be affected by many other factors.

   In response to this challenge, the ASPMN published a position statement that recommends a comprehensive, hierarchical approach to the assessment of pain in nonverbal patients, which provides the framework for a decision-making process that can be used to manage pain in nonverbal patients. The hierarchical approach has 5 key steps:

1. When possible, obtain self-report.
2. Look for possible pathologies, procedures, or other causes of pain.
3. Observe for behaviors that may indicate the presence of pain.
4. Obtain input from caretakers who know the patient and the patient's usual behaviors and responses
    to pain.
5. Use an analgesic trial and observe for changes in behavior.

Step 1: Patient self-report of pain.

   The hierarchy affirms that the patient's self-report is the most reliable indicator of pain and the sole indicator of pain intensity. Ascertaining the patient's report of pain should always be attempted first. Reliability of the patient's self report may diminish with advancing cognitive impairment, but many valid and reliable tools are available that may be effectively used with cognitively impaired persons. No method has been identified to establish a patient's ability to reliably use a self-report tool; it is therefore helpful to have several tools available in the clinical setting so that the tool that yields the most consistent results for the individual patient may be selected. Once identified, this tool should be used at each assessment.

Step 2: Assumption of pain.

   If a reliable self-report of pain cannot be elicited, the next step in the hierarchy is to consider whether the patient has a condition that is typically associated with pain or is undergoing procedures that are generally considered painful. In such cases, the nurse should "assume that pain is present" (abbreviated "APP" for documentation when approved by facility policy and procedure) and provide the appropriate treatment. It is never appropriate to assume that a patient who is unresponsive, nonverbal, confused, demented, or delirious cannot feel or is not feeling pain. Similarly, pain must be assumed to be present and treated if the patient who is receiving paralytics or sedatives has an underlying painful condition or is undergoing painful procedures.

Step 3: Behavioral indicators of pain.

   The third step in the hierarchy requires the nurse to observe the patient for possible indicators of pain, such as grimacing or other indicative facial expressions, bracing, rocking, or changes in activity. Recognizing that certain behaviors may indicate pain, researchers have developed behavioral pain assessment tools for use in patients who cannot self-report. Many of these tools yield a behavioral score that can help determine the presence of pain, and when changes are noted, can be used to evaluate the effectiveness of interventions; however, a behavioral score is not a pain intensity score. If the patient cannot report the intensity of his or her pain, then the intensity is unknown.

Tools for pain assessment include:

1.  The Critical Care Pain Observation Tool (CPOT) was designed to assess pain in critically ill adults.

     It uses facial expression, body movement, muscle tension, and ventilator compliance or

     vocalization as pain indicators.

2. The Payen Behavioral Pain Scale, which uses facial expression, upper extremity movement, and

     ventilator compliance as pain indicators, may also be used for critically ill adults who are intubated.

3. The Pain Assessment in Advanced Dementia (PAINAD) is used to assess pain in patients who have

    dementia or Alzheimer's disease and are nonverbal. It uses breathing, negative vocalization, facial

    expression, body language, and consolability as pain measures.

   City of Hope Research (Visit&Contact: cityofhope.org) provides a brief summary and critique of many of the tools that have been developed for the assessment of pain in nonverbal patients. Validity and reliability have not yet been fully established for some of these tools. As with pain intensity scales, behavioral tools should be used only in the patient populations for which they were intended and in patients who are able to respond with the requisite behaviors for each tool. Although many tools have been developed to aid in the assessment of pain, the patient's self-report of pain intensity remains the most dependable method of pain assessment.

Step 4: Solicit information from caregivers and family members.

   A surrogate who knows the patient's usual behavioral responses can provide input about pain behaviors, which can be valuable in identifying the patient's unique responses to pain.

Step 5: Analgesic trial.

   The last step of the hierarchy of measures is an analgesic trial, which involves observing the patient's behavior before and after administration of a low dose of analgesic medication. An improvement in behaviors after the analgesic dose helps confirm the presence of pain and serves as the basis for a pain treatment plan. If the patient does not respond to the trial, an increase of the analgesic dose or trial of a different analgesic should be attempted. If the behaviors do not improve despite optimal titration of the analgesic regimen, causes of the behaviors other than pain should be considered