A World of Hurt

Joan, a 60-year-old female, is supine on the floor, with her right hip supported by a pillow. "I broke my hip," she says calmly. "As long as I don't try to move it doesn't hurt." She tells you she tripped on an area rug in her kitchen and landed directly on her right hip. She reports pain and tenderness to palpation and has normal distal sensation and circulation. As we discuss options to minimize her pain during movement, I think about how pain signals are transmitted from the injury area to the brain and wonder how we can accurately assess Joan's pain.

Pain is the leading emergency medicine complaint, and its underlying causes are often of secondary concern to the patient.¹ Patients expect EMS to acknowledge their pain, assess it and treat it. The first step in improving assessment and treatment is to understand the pathophysiology and assessment of pain.²

WHAT IS PAIN?
The desire for pain relief often supercedes a patient's desire to identify and resolve the cause of pain. A position paper by the National Association of EMS Physicians says, "The NAEMSP believes that the relief of pain and suffering of patients must be a priority for every emergency medical services system."³

Understanding the underlying process or pathophysiology increases the likelihood an EMT will act on that knowledge. It is easy to say "give aspirin to any adult patient with chest pain"; however, understanding the cause of pain, like ischemic cardiac tissue; knowing how to assess the pain and differentiate it from among other potential causes, such as cardiac chest pain/pressure vs. respiratory tightness and shortness of breath; and understanding that aspirin inhibits platelet aggregation leads to faster and more effective treatment.

Pain is defined by the patient, not the caregiver. The International Association for the Study of Pain states that pain is "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage."⁴

Pain is a protective mechanism whenever body tissue is damaged. The pain stimulus triggers a cascade of emotional, physical and sensory reactions to communicate and lessen the pain.²

There is no predictable relationship between tissue damage and pain. Patients often report pain significantly higher or lower than what we might expect based on observable damage.⁵ Pain is a personal experience. Two patients with an identical injury or illness may have very different pain response and tolerance.

According to the American Pain Society, "Low back pain, arthritis and migraine headache alone account for pain in tens of millions of Americans."⁴ Annually, 25 million Americans have acute pain from injury or surgery, and 50 million suffer from chronic pain.⁴ Chronic pain is the most common cause of long-term disability, and symptoms often persist for years.

RESPONDING TO PAIN
For many patients, the impact and costs of pain, especially traumatic pain, begin with prehospital pain assessment and treatment. Research has documented that prehospital personnel can fail to recognize and properly treat pain.²

Most prehospital pain is nociceptive. Nociception includes four steps: transduction, transmission, perception and modulation.⁴ Transduction is the conversion of energy in a pain receptor from a noxious stimulus into a nerve impulse.^2,4,5 Pain receptors are arranged on free nerve endings in the superficial layers of the skin and walls of internal organ tissues. They are activated by chemical, mechanical or thermal noxious stimuli. For example, a nail through the foot is a noxious mechanical stimulus that causes damage to the skin and muscle tissues. Damaged foot tissue releases sensitizing substances that activate nociceptors. An action potential is created at the nociceptor, initiating an electrical charge that sends a nerve impulse to the brain.⁵