Pain is defined as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage."1 Acute pain is defined as pain that lasts for a short period of time, alerts the body that it has been injured, and is the result of tissue injury.1 Chronic or persistent pain is pain that lasts beyond the normal healing period, does not have a meaning, and is often accompanied by depression.2 Some patients with acute pain may have underlying chronic pain, which makes the acute pain more difficult to treat.