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Operational Medicine 2001
GMO Manual
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General Medical Officer (GMO) Manual: Clinical Section Acute Pain ManagementDepartment of the Navy Because most patients in acute pain can be adequately treated with narcotics, the occurrence of inadequate pain relief usually relates to inappropriate administration. Several factors contribute to this problem. Often dosage duration and strength are miscalculated. Clinicians also tend to unduly emphasize the risks of narcotic therapy; respiratory depression (discussed later) and addiction. Addiction represents a syndrome of psychological dependence on a drug and aberrant drug related behaviors, leading to an overwhelming involvement with the drug. In contrast, physical dependence is a pharmacological property of narcotics characterized by the development of an abstinence syndrome upon abrupt discontinuation of the narcotic. This is not addiction, and is not itself a substantial risk in clinical practice, because any adverse effects can be prevented by tapering the drug before discontinuation. Surveys of postoperative or burn patients indicate that less than 0.5 percent of patients with no prior history of substance abuse will develop problems after therapeutic use. Therefore, the risk of addiction should not be used to justify limited administration of the narcotic in the treatment of acute pain.The minimum effective analgesic concentration (MEAC) is the lowest blood concentration of narcotic agonist consistent with the patient's report of complete analgesia. The MEAC varies at least five-fold among patients. The physician relies upon the patient's report on the quality of the pain. Pain is always subjective.
The mainstay of pain management is as needed (PRN) dosing. However, there are two reasons why PRN dosing regimens for acute pain may fail. First, patients usually expect pain relief to be delivered immediately upon request. PRN dosing can frequently contribute to a failure in this process. This occurs because either the patient waits too long to request more pain medication or, the staff cannot immediately administer the drug. Second, blood concentrations fluctuate between 4 hour dosing intervals (e.g., meperidine 50-75 mg IM q 4 hours PRN pain) such that the MEAC is maintained only 35 percent of the time, or patients are in pain 65 percent of the time. Drugs used in the treatment of acute pain must be viewed as agents that need to be titrated on a frequent basis rather than being administered on a set dosing regimen determined by the average patient.Stepcare Approach
Step 2 Step 3 Step 4 Remember intramuscular (IM) narcotic therapy results in large swings in concentrations, is uncomfortable for the patient, and provides analgesia for less than 50 percent of the every 4-hour dosing regimen. However in some cases, IM narcotic therapy may be the best available option (e.g. for a patient being transported without direct physician supervision). For intravenous therapy, initiate treatment with small aliquots of narcotic (e. g. morphine sulfate 2 to 4 mg every 5-10 minutes). Adjust the dose depending on the patient’s age and physical condition. After 2 to 3 hours, an average hourly requirement can be determined. It is imperative to anticipate the adverse effects of narcotic use. Constipation, sedation, nausea, and vomiting are expected adverse effects. Providing stool softeners, careful monitoring, and antiemetics prophylactically will prevent many of these problems. Respiratory depression is probably the best example of a serious adverse pharmacological effect that is only rarely encountered clinically but generates concern sufficient to cause undertreatment. The occurrence of respiratory depression is extremely uncommon in patients who undergo gradually escalating doses. Narcotic induced respiratory depression, if not caused by a massive overdose, is always heralded by the gradual onset of obtundation and slowed respiratory rate: signs that signal an impending problem that needs to be managed appropriately. Monitoring drug effects by assessing the level of consciousness and respiratory rate can greatly diminish the risk of serious respiratory depression. Revised by CAPT C.G. Bush, MC, USN, Anesthesia Department, Naval Hospital, Groton, CT. (1999). Approved for public release; Distribution is unlimited. The listing of any non-Federal product in this CD is not an endorsement of the product itself, but simply an acknowledgement of the source. Operational Medicine 2001 Health Care in Military Settings
This web version is provided by The Brookside Associates Medical Education Division. It contains original contents from the official US Navy NAVMED P-5139, but has been reformatted for web access and includes advertising and links that were not present in the original version. This web version has not been approved by the Department of the Navy or the Department of Defense. The presence of any advertising on these pages does not constitute an endorsement of that product or service by either the US Department of Defense or the Brookside Associates. The Brookside Associates is a private organization, not affiliated with the United States Department of Defense. |