Acute Pain Management in the Emergency Department

By James Miner, MD

December 31, 2009: Pain is the presenting complaint for up to 70% of visits to the Emergency Department (ED). The treatment of acute pain is essentially a simple process and a wide variety of effective agents and techniques are available. Developing consistent and effective approaches to the management of a wide variety of painful conditions can optimize a physician’s ability to deal with pain in two ways. First, using the most effective strategies will allow one to treat pain effectively with the least possible side effects. Second, limiting side effects simplifies patient selection by minimizing the downside of patient treatment.

An accurate recognition and assessment of a patient’s pain is the central aspect of effective pain management and is essential to any effective analgesic strategy. This process, however, is subjective and complex, and is not entirely understood.

Acute pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage as well as activation of neurochemical receptor and mediator responses. Acute pain is always a subjective. Objective observations (grimacing, tachycardia) may be present, but these signs are often absent. As a consequence, pain assessment is an indirect estimation by the treating physician. This is generally obtained by asking the patient to describe their pain. A numeric rating scale from 1-10, with 1 as no pain and 10 as the most pain imaginable, works for most patients older than 7 who can cognitively understand numbers. Simply asking a patient whether their pain is minimal, moderate, or severe is likely just as effective as a 1-10 scale, and may be preferable. These scales are communication tools rather than actual measures of pain; a patient with a high score wants treatment immediately, a patient with a low score is less concerned about it. Repeating the measurement after treatment and throughout a patients care can describe the effectiveness of any pain treatments used and the progression of a patient’s condition.

Because pain is assessed almost completely through patient report, patients who have difficulty communicating are at risk of under-treatment due to under-appreciation of their pain. Groups at risk include infants and children, patient’s whose cultural background differs significantly from the treating physician’s, and patients who are developmentally delayed, cognitively impaired, under severe emotional stress, or mentally ill. When treating patients such as this, it is important to consider the fact that pain can only be measured effectively through report, so that an estimation of a non-communicative patient’s pain must be made based on the patient’s illness or injury, and how much it would probably hurt someone who could communicate, rather than the vital signs or appearance of the patient.

Many physicians have encountered patients who have altered a prescription, lost pain medications, seem to have pain out of proportion to their illness or injury, or who ignore follow-up clinic appointments and return to the ED repeatedly. These experiences can make it easy to view a patient’s report of pain with scepticism. However, such observations and experiences, like the physician’s assessment of patient pain, are significantly dependent on verbal and non-verbal subjective communication between the physician and patient. This reality creates a substantial potential for inaccurate interpretations of patient motives in clinical conditions where the patient pain experience is largely subjective (e.g. back pain) with minimal opportunity for objective clinical assessment with modalities such as radiographic imaging or laboratory testing.

During an emergency, when the cause of a patient’s pain is uncertain, establishing a diagnosis is the priority of the Emergency Physician, but symptomatic treatment of pain should be initiated while the investigation is proceeding. In general, it is inappropriate to delay analgesic use until a diagnosis has been made. It is unlikely that treatment with 0.1 mg/kg of morphine, or another analgesic equivalent, will mask signs or symptoms of progressive disease. A generalized approach to the treatment of acute pain in the ED is in figure 1.

About the Author:
James Miner, MD
Associate Professor
Department of Emergency Medicine, University of Minnesota
Medical Director
Emergency Medicine Quality Assurance
Research Director
Department of Emergency Medicine, Hennepin County Medical Center

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