Pain is a complex, subjective response with several quantifiable features, including intensity, time course, quality, impact, and personal meaning. The reporting of pain is a social transaction between caregiver and patient. Therefore, successful assessment and control of postoperative pain depends in part on establishing a positive relationship between health care providers, patients, and (when appropriate) their families. Studies have shown that patients provided with information related to physiological coping (instruction in coughing, deep breathing, turning, and ambulation) reported less pain (Fortin, and Kirouac, 1976), were given fewer analgesics postoperatively (Fortin, and Kirouac, 1976 ; Voshall, 1980), and had shorter lengths of stay (Van Aernam, and Lindeman, 1971). Egbert, Battit, Welch, and Bartlett (1964) found that providing patients sensory information preoperatively (i.e., detailed descriptions of discomforts to be expected postoperatively) decreased pain, analgesic use, and length of stay. Still other researchers found that patients provided with procedural and sensory information as well as instructions related to physiological coping tended to receive fewer analgesics (Reading, 1982 ; Schmitt, and Wooldridge, 1973) and had shorter lengths of stay than patients who were given less complete information (Schmitt, and Wooldridge, 1973).

As noted in the flow charts (Figures 1 and 2), the subject of postoperative pain and its control is a critical part of the initial review of all relevant aspects of the planned procedure. The surgeon should discuss this with the patient and the family. In addition, pain assessment and management issues should be a part of the preoperative workups of the anesthesia and nursing staffs. Patients and their families should be informed that pain reports are valuable and important information, and also that pain may herald surgical complications that demand prompt diagnosis and therapy. To aid in planning and discussing pain control strategies with the patient, a member of the anesthesiology department should obtain a pain history during the preoperative visit. The pain history should include:

• Significant previous and/or ongoing instances of pain and its effect on the patient;
• Previously used methods for pain control that the patient has found either helpful or unhelpful;
• The patient's attitude toward and use of opioid, anxiolytic, or other medications, including any history of substance abuse;
• The patient's typical coping response for stress or pain, including more broadly, the presence or absence of psychiatric disorders such as depression, anxiety, or psychosis;
• Family expectations and beliefs concerning pain, stress, and postoperative course;
• Ways the patient describes or shows pain; and
• The patient's knowledge of, expectations about, and preferences for pain management methods and for receiving information about pain management.

Some patients fear overmedication (e.g., "They will medicate me into oblivion so that I won't be any trouble"). Others know from previous experience that they are prone to side effects of certain drugs (e.g., dysphoria or nausea). Patients who express fears or concerns related to previous analgesic effects may require a cautious approach to medication. Preoperative anxiety may indicate a concurrent medical condition such as substance abuse or withdrawal, hyperthyroidism, anxiety disorder, affective disorder, psychosis, or a medication side effect. Excessive preoperative anxiety should be assessed and a psychiatric or psychologic consultation considered to assist with perioperative management. When the preoperative assessment is complete (as noted in Figure 1), the health care team should develop a pain management plan in collaboration with the patient. When developing the pain management plan, clinicians must consider the relative risks, benefits, and costs of available pain control options. They also should attempt to correct patient misconceptions about the use of pharmacologic or nonpharmacologic strategies.

Once a pain management plan is in place, preoperative preparation of the patient and family is extremely important. Preoperative preparation of patients (and families, when appropriate) assists patients in understanding their responsibilities in pain management. To ensure that postoperative pain measurement is both valid and reliable, the staff should review the selected pain measurement tool -- for example, a simple descriptive scale or a visual analog scale -- with the patient before surgery. Pain assessment instruments are discussed below and samples are provided in appendix D. The patient should be told how frequently pain will be assessed and asked to select a measurement tool. A member of the health care team should advise the patient that a score above some predetermined criterion of the patient's choosing (e.g., a score of 3-4 on a 10-point scale) will result in a dose increment or other intervention. The patient's negotiation of this criterion is particularly important if the patient fears overmedication or intends to cope psychologically with the pain. Patient preferences should be supported.

Assessment of pain after surgery should be frequent and simple. Many different measurement tools are available, and several factors help determine the best choices (Chapman, and Syrjala, 1990). First, consider the patient's age; developmental status; physical, emotional, or cognitive condition; and preference. Second, consider the expertise, time, and effort available from the individual performing the assessment. Third, examine the institution's requirements for monitoring and documentation for quality assurance purposes. Based on these factors, each health care institution should educate staff in the proper and consistent use of a valid assessment tool(s) and establish its own quality assurance program for evaluation of postoperative pain assessment and management (American Pain Society, 1990, 1991 ; National Institutes of Health, 1987). For example, recording pain intensity on the bedside vital sign chart may be considered necessary to make the assessment easily accessible to members of the health care team. In addition, each institution should identify individuals responsible for postoperative pain assessment and control.

The single most reliable indicator of the existence and intensity of acute pain -- and any resultant affective discomfort or distress -- is the patient's self-report.

A comprehensive approach to postoperative pain assessment requires evaluation of: 1) patient perceptions; 2) physiological responses; 3) behavioral responses; and 4) cognitive attempts by the patient to manage pain. Physiological responses such as heart rate, blood pressure, and respiratory rate provide critical information in the immediate postoperative period. Once the patient has recovered from anesthesia, the mainstay of pain assessment should be the patient's self-report to assess pain perceptions (including description, location, intensity/severity, and aggravating, and relieving factors) and cognitive response. Patient self-report is the single most reliable indicator of the existence and intensity of acute pain and any concomitant affective discomfort or distress (National Institutes of Health, 1987). Neither behavior nor vital signs can substitute for a self-report (Beyer, McGrath, and Berde, 1990). Patients may be experiencing excruciating pain even while smiling and using laughter as coping mechanisms (Fritz, 1988).

Samples of commonly used pain assessment tools are in appendix D. Three common self-report measurement tools useful for assessment of pain intensity and affective distress in adults and many children are: 1) a numerical rating scale (NRS); 2) a visual analog scale (VAS); and 3) an adjective rating scale (ARS). While many researchers prefer visual analog measures (Scott, and Huskisson, 1976 ; Sriwatanakul, Kelvie, Lasagna, Calimlim, Weis, and Mehta, 1983), each of these tools can be a valid and reliable instrument as long as end points and adjective descriptors are carefully selected (Gracely, and Wolskee, 1983 ; Houde, 1982 ; Sriwatanakul, Kelvie, and Lasagna, 1982).

In practical use, the visual analog scale is always presented graphically, usually with a 10-cm baseline and endpoint adjective descriptors. Patients place a mark on the line at a point that best represents their pain. The visual analog scale is scored by measuring the distance of a patient's mark from the zero. The numerical and adjective rating scales may be presented graphically (see appendix D) or in other formats. For example, numerical rating scales are sometimes presented verbally, and adjective rating scales are presented as a list of pain descriptors. In a graphic format, scoring of the numerical and adjective rating scales may be the same as that described above for the visual analog scale, or they can be scored as numeric integers.

For each of these scales, the clinician should request the patient's self- report, not only with the patient at rest but also during routine activity such as coughing, deep breathing, or moving (e.g., turning in bed). Complaints of pain must be heeded. The patient should be observed for behaviors that often indicate pain, such as splinting the operative site, distorted posture, impaired mobility, insomnia, anxiety, attention seeking, and depression. Patient awareness of pain and the ability to control pain are important components of pain assessment. If pain behavior is observed or if the patient expresses feelings of inadequate control, a member of the health care team should discuss these with the patient and share this information with other members of the team. The management plan should then be revised as needed.

The clinician should document the patient's preferred tool for pain assessment and the goal for postoperative pain control as expressed by a score on a pain scale in the patient's chart as part of the pain history. Simply to record patient responses to the question "how is your pain?" invites misunderstanding or denial and hinders quantification. Pain should be assessed and documented: 1) preoperatively; 2) routinely at regular intervals postoperatively, as determined by the operation and severity of the pain (e.g., every 2 hours while awake for 1 day after surgery); 3) with each new report of pain; and 4) at a suitable interval after each analgesic intervention (e.g., 30 minutes after parenteral drug therapy, and 1 hour after oral analgesics). Most important, the team should evaluate immediately each instance of unexpected intense pain, particularly if sudden or associated with oliguria or altered vital signs such as hypotension, tachycardia, or fever, and consider new diagnoses such as wound dehiscence, infection, or deep venous thrombosis.

Each instance of unexpected intense pain, particularly if sudden or associated with oliguria or altered viatl signs such as hypotension, tachycardia, or fever, should be immediately evaluated to consider new diagnoses such as wound dehiscence, infection, or deep venous thrombosis.

Occasionally, apparent discrepancies between behaviors and a patient's self-report of pain may occur. For example, patients may describe pain as an 8 out of 10 on a pain scale while smiling and walking freely or as 2 out of 10 while tachycardic, splinting, and sweating. Discrepancies between behavior and a patient's self-report may result from excellent coping skills. The patient who uses distraction and relaxation techniques may engage in diversionary activities while still experiencing severe pain. Patients may deny severe pain for a variety of reasons, including fear of inadequate pain control or a perception that stoicism is expected or rewarded. Similarly, patients managed with as- needed analgesia may perceive that medication will be given only if the pain score is very high. Patients who perceive staff as inattentive to their concerns may use pain as a way to get help for other reasons.

When discussing pain assessment and control with patients, members of the health care team should emphasize the importance of a factual report, thereby avoiding both stoicism and exaggeration. Patients with anxiety or other concerns should rate their mood and emotional distress separately from their pain by using similar scales (see Pain Distress Scales in appendix D). When discrepancies between behaviors and self- reports of pain occur, clinicians should address these differences with the patient. The team and the patient should then renegotiate the pain management plan.

Patients unable to communicate effectively with staff require special consideration for pain assessment, e.g., neonates and children, developmentally delayed persons, psychotic patients, patients with dementia, and non-English speaking patients. Children and cognitively impaired patients require simpler or modified pain measurement scales and assessment approaches (see section on pain in children). The staff should work with both the patient and parent or guardian pre- and postoperatively. Staff should endeavor to find a translator for the non-English speaking patient, at least once, to determine a convenient way to assess pain. Members of the health care team should attend to the preferences and needs of patients whose education or cultural tradition may impede effective communication. Certain cultures have strong beliefs about pain and its management, and these patients may hesitate to complain about unrelieved pain. Such beliefs and preferences should be determined and respected, if at all possible.In summary, health care providers should view good pain control as a source of pride and a major responsibility in quality care. Support personnel otherwise untrained in pain assessment should be encouraged to be "pain vigilant" and report to the health care team any patient discomfort, such as during transport or transfer to an x-ray table. At the institutional level, periodic evaluation studies should be conducted to monitor the effectiveness of pain assessment and management procedures. Without institutional support for an organized process by which pain is recognized, documented, assessed, and reassessed on a regular basis, staff efforts to treat pain may become sporadic and ineffectual. A pain care process relying on patients' or families' demands for analgesia "as needed" will produce intervals of inadequate pain control and worsen burdens of anxiety, loss of personal control, sleeplessness, and fatigue after surgery. Patients and their families should understand that pain relief is an important part of their health care, that information about options to control pain is available, and that they are welcome to discuss their preferences with the health care team. Patients should recognize that health professionals will elicit and respond quickly to their pain reports. Before a patient's discharge, those taking care of the patient should describe the interventions used to manage pain and assess their effectiveness. This review, while good practice for each patient, is especially important when initial management was unsuccessful and/or when side effects or other complications occurred.