Correspondence  |   September 1999
Intramuscular Opioid Injections: A Step in the Wrong Direction 
Author Notes
  • Research Associate Professor
  • Department of Anesthesia
  • Faculty of Medicine, University of Montreal
  • Montréal, Québec, Canada
  • Director
  • ICOM Health Original Investigations
  • Johnson and Johnson
  • Raritan, New Jersey
  • Clinical Associate Professor
  • Department of Medicine
  • Robert Wood Johnson School of Medicine
  • University of Medicine and Dentistry of New Jersey
  • New Brunswick, New Jersey
  • Assistant Professor
  • Department of Anesthesia
  • Faculty of Medicine
  • McGill University
  • Montreal, Quebec, Canada
Article Information
Correspondence   |   September 1999
Intramuscular Opioid Injections: A Step in the Wrong Direction 
Anesthesiology 9 1999, Vol.91, 891. doi:
Anesthesiology 9 1999, Vol.91, 891. doi:
In Reply:—
We appreciate the comments of Dr. Fitzgibbon et al.  regarding our study, which shows that regularly nurse-administered intramuscular (IM) injections of morphine are less costly and provide comparable analgesia to patient-controlled analgesia (PCA) after hysterectomy. 1 We welcome the opportunity to elaborate on important issues that we could not address in our article because of space limitations. We want to emphasize from the onset that we did not propose to “return to the dark days of postoperative pain management.” Similarly, their concluding remark, that “IM injections of opioids has had its day and failed miserably,” applies solely to on-demand scheduling of administration, which we believe is irrelevant to our findings. In our study, we purposely chose not to compare PCA with on-demand IM injections precisely because of the well-recognized inadequacies of this mode of administration. 2,3 Instead, we chose to assess the comparative benefits of PCA versus  regular IM dosing in terms of efficacy and cost.
Our results showed that the two techniques were equally effective, but the patients on IM therapy received more morphine, required a greater number of dose adjustments, and consumed more nursing time. Fitzgibbon et al.  argue that this is perhaps a testament to the individualization, ease of administration, and overall success of PCA. They are right in a way, but they omit several important points, including the cost of the technique, a crucial element to consider in these days of increasing budget constraints in our healthcare system. Our study is the first to provide a thorough cost analysis of PCA. This analysis showed that PCA was more costly than regularly nurse-administered IM injections, although the cost for the pumps themselves were counted as zero. Considering that the two techniques were equally efficacious, one must ask whether one wants to pay extra for something that is no better.
Patient satisfaction is obviously an important aspect to consider in such a context. According to Fitzgibbon et al.  , if we had used a crossover design so that our patients had the chance to compare the two techniques, they might have preferred PCA. They are probably right. IM injections are indeed painful, but it is common clinical practice to rotate the injection site to different areas (buttocks, arms, thighs) to minimize patient discomfort. Our suggestion, 1 to replace the IM injections by subcutaneous injections administered through a winged infusion set, is an even better solution that probably would enhance patient satisfaction. But even if patients persist in preferring PCA to nurse-administered subcutaneous injections, two issues still must be considered. First, the preference for PCA should be of such a magnitude that it overwhelms the cost advantage of IM therapy (mild preference in the face of important cost disparities is not a compelling argument). Based on previous observations, 4–6 this seems doubtful, but further research is clearly needed in this field. 7 Patient satisfaction ratings are usually very high irrespective of the analgesic regimen used, and it is by no means clear what such ratings represent. 8–10 As pointed out by Egen and Ready, 8 patient satisfaction with postoperative analgesic care is a complex issue. It encompasses and reflects many factors such as personal preference, patient expectation about pain relief, communication with healthcare providers, perceived compassion, etc.  8–10 Progress in this area requires more studies on the sources of patient satisfaction (or dissatisfaction) with PCA and other types of analgesic regimens. However, these satisfaction ratings should not be used in isolation from other data such as postoperative pain scores and medication intake because they could lead to erroneous conclusions about the quality of pain management. 7 
A second and perhaps more important issue is that patient preference for a given analgesic method is far from being a guarantee of its efficacy. Several studies 9,10 have shown that patients reported being highly satisfied with their analgesic treatment despite the fact that they experienced relatively high pain levels. Patient satisfaction does not equate to pain relief. In the PCA literature, several reports 11–13 indicate that patients who use this technique rarely medicate themselves to optimal or complete pain relief. Reasons are numerous and include fear of experiencing drug side effects, concern about drug addiction, educational attitudes toward pain, and religious beliefs. Nevertheless, these same patients report being highly satisfied with the “machine” and, paradoxically, some of them are even proud of saying that they did not use it very much. In our study, PCA patients consumed less morphine than those who received IM therapy, and it is interesting to note that the mean VAS scores on all of the measures assessing pain at rest and with movement were slightly but consistently higher in the PCA group, even during the first 24 h of the study. Results on the pain relief measure and the recovery parameters also tended to not favor PCA therapy (tables 3 and 4 in our original article 1). The group differences reached the fixed level of statistical significance on one of the measures where the PCA patients were found to take significantly longer to be able to sit in a chair without assistance. A tendency also emerged for them to report more pain when walking than IM patients (the difference was significant at 0.03 but did not meet the Bonferroni's corrected alpha level).† These observations are interesting and we were tempted to mention them in our article, but we wanted to avoid any suggestion that the group differences were real differences (as defined by achieving statistical significance). However, the best estimates of the differences did not favor PCA therapy.
With regard to the ease of applicability of the regular IM regimen, we did not collect any measures, although it would have been interesting to do so. However, administering the drug on time did not seem to be a problem. Rescue dose and dosage adjustments were time-consuming, but the procedure was made easier by the use of a standardized protocol for increasing or decreasing the medication, which was part of the prescription order included in patients’ medical files.
In the real-life situation (as opposed to the somewhat artificial environment of a study), regular IM (or subcutaneous) dosing can probably be made easier (and less nurse-intensive and consequently cheaper yet) by synchronizing the injections with other fixed duties (e.g.  , vital signs), which was not the case during the course of our study. PCA certainly requires less nursing time, but it does not guarantee adequate pain control and its expense overwhelms any nursing cost disadvantages of regular IM injections. Dr. Ready himself has suggested elsewhere 14 that proper PCA use is not without its own share of nursing time commitment:“There is a widespread misconception that pain relief with PCA is completely automatic. In fact, PCA can only be used optimally when it is accompanied by regular, expert nursing and medical supervision.” So, the argument presented in the letter that hospitals will eventually move toward providing less-skilled workers to care for postoperative patients (supposedly to the sole detriment of the regular IM injections regimen) also holds for PCA.
In conclusion, all of us are in search of better pain management, not merely pushing favorite methods in the face of significant contrary evidence. PCA has its advantages and disadvantages. The same is true for regularly nurse-administered analgesia. However, it is incorrect to argue that regular IM injections of opioids for controlling postoperative pain are “a step in the wrong direction.” Their use is a step in a different direction that provides value commensurate with resource outlays. Until such time as PCA is able prove itself to have such a superiority in patient preference (including strength of preference, not just direction of preference) that it overwhelms its cost and perhaps efficacy disadvantages, it will seem (at least in this indication) to be a high-tech solution where none is needed. Such solutions are often falsely attractive.
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