The Effectiveness of Small Doses of Ketamine With Morphine on Decreasing Pain Responses During Open Wound Care

An open wound care procedure causes pain and sometimes the use of medication such as morphine alone does not adequately help to alleviate pain during this procedure. This study is being done to learn if the administration of another medication named ketamine by the vein in addition to morphine is more effective in alleviating pain during the wound cleansing procedure than the administration of morphine alone. Patients will be eligible for the study if they are 21 years and older, have an open surgical or traumatic wound with a duration of no more than 10 days, had a wound pain intensity score more than 3 in a scale of 0 to 10 where 0 is no pain and 10 is the worst pain imaginable during a previous wound care procedure, and have an intravenous access.

A total of 50 patients with these same characteristics are expected to take part in this study. Patients who agree to take part in this study will, one day, receive receive an injection via the vein of morphine 0.05 mg per kilogram of their weight (maximum dose of 4 mg) and another of ketamine 0.25 mg per kilogram of their weight prior receiving the wound care procedure and, on the other day, will receive an injection via the vein of morphine 0.1 mg per kilogram of their weight (maximum dose of 8 mg) and another of saline prior receiving the wound care procedure. They will not be able to know if they receive ketamine or saline the first time or second time.

Ketamine is a drug approved by the U.S. Food and Drug Administration (FDA) for anesthesia but not approved to provide analgesia (relieve pain). However, small doses of ketamine are used (out of its indications) in the clinical area to provide analgesia, and its analgesic properties have been studied by many researchers.

Before the wound care procedure subjects will be asked to rate their wound pain intensity at rest at that moment and in the past 24 hours (including "worst" and "average" pain), overall pain intensity at rest at this moment and "worst" and "average" in the past 24 hours using a 0 to 10 scale where 0 is no pain and 10 is the worst pain imaginable. They will be given a list of common words that might describe their pain, and a body outline to indicate where the pain is. In addition, they will be asked to rate their level of sleepiness using a 0 to 10 scale where 0 is not at all sleepy and 10 is extremely sleepy.

After removing the outer dressing, patients will be tested for pain sensitivity around the wound with a thin, short length of plastic (like a little straw), which will be pressed against their skin from the outside of the wound towards the wound and they will be asked to report a distinct change in perception. The first point where a "painful", "sore", or "sharper" feeling occurs will be marked in the skin to measure the distance of this mark to the wound. If no change in perception occurs, stimulation will be stopped 0.5 cm from the wound. This measure is experimental.