Correlates of postoperative pain and intravenous patient-controlled analgesia use in younger and older surgical patients

Patterns of postoperative pain medication prescribing after invasive dental procedures

We investigated disparities in the prescription of analgesics following dental procedures that were expected to cause acute postoperative pain. Patients over the age of 19 years who had been treated by surgical and/or endodontic dental procedures were included in this study. We reviewed 900 consecutive charts and abstracted data on procedures, patients, and providers. We used chi-square and logistic regression models for analyses. There were 485 White subjects, 357 African American subjects included in this review; 81% of the African American and 78% of White patients received a postoperative narcotic prescription (p = .56). In multivariate regression models, patients over age 45 (p = .003), those with insurance that covered medication and those with preexisting pain (p = .004) were more likely to receive narcotic analgesics. Students prescribed more narcotics than residents (p = .001). No differences were found by race in prescribing analgesics.

[Treating acute postoperative pain: evaluation of results on the surgical ward]

OBJECTIVE

To describe management of acute postoperative pain on the surgical ward. To study the relationship between pain and a variety of surgical procedures and approaches. To determine the level of information patients received, their expectations, and their satisfaction with treatment of postoperative pain.

PATIENTS AND METHODS

Cross-sectional observational study by survey and review of patient records. We studied 234 patients, including all who were hospitalized for more than 24 hours after scheduled or emergency operations. The main variables recorded were pain intensity at rest and during movement, including on the day after surgery, and the surgical procedure and approach.

RESULTS

The prevalence of pain (>3 on a numerical scale) on the surgical ward was 33% at rest and 66% during movement. The prevalence of intense pain (>6 on the numerical scale) was 1.7% at rest and 7.3% during movement. Factors related to greater pain intensity were timing, that is, the first day after surgery, when 74.4% of patients experienced their most intense pain; type of surgery and approach (P<.004); and expecting to experience moderate or intense pain (P<.001).

CONCLUSIONS

Recording the prevalence of postoperative pain on a surgical ward provides information about the real situation of acute postoperative pain control. Pain on movement is a principal indicator for detecting groups of patients for whom analgesic protocols could be improved. Type of surgery and approach is a fundamental factor to consider when comparing the results of analgesic protocols.

Do sex differences exist in opioid analgesia? A systematic review and meta-analysis of human experimental and clinical studies

Although a contribution of sex in opioid efficacy has garnered much attention, the confirmation and direction of any such difference remain elusive. We performed a systematic review of the available literature on sex differences in μ and mixed μ/κ opioid effect on acute and experimental pain. Fifty unique studies (including three unpublished studies) were included in the analyses. Across the 25 clinical studies on μ-opioids there was no significant sex-analgesia association. Restricting the analysis to patient-controlled analgesia (PCA) studies (irrespective of the opioid) yielded greater analgesia in women (n=15, effect size 0.22, 95% c.i. 0.02-0.42, P=0.028). Further restricting the analysis to PCA morphine studies yielded an even greater effect in women (n=11, effect size=0.36, 95% c.i. 0.17-0.56, P=0.003). Meta-regression indicated that the longer the duration of PCA, the difference in effect between the sexes further increased. Across experimental pain studies on μ-opioids women had greater antinociception from opioids (n=11, effect size=0.35; 95% c.i. 0.01-0.69, P=0.047), which was predominantly due to 6 morphine studies. Female patients had greater μ/κ opioid analgesia (n=7, effect size 0.84; 95% c.i. 0.25-1.43, P=0.005), but no sex-analgesia association was present in experimental studies (n=7). Sex differences exist in morphine-induced analgesia in both experimental pain studies and clinical PCA studies, with greater morphine efficacy in women. The data on non-morphine μ and mixed μ/κ-opioids are less convincing and require further study.

Assessment of early post-operative pain following septorhinoplasty

OBJECTIVE

To evaluate pain incidence and intensity in patients undergoing septorhinoplasty, and to assess analgesic treatment effectiveness, in the first 7 days after surgery.

DESIGN

Prospective outcomes analysis using visual analogue scale assessment of pain intensity in the first 7 post-operative days.

SUBJECTS

Fifty-seven patients were enrolled in the study, 29 women and 28 men, aged 18 to 51 years. All were treated for post-traumatic deformity of the external nose and/or nasal septum, with either septorhinoplasty or septoplasty.

RESULTS

In the first 3 days after septorhinoplasty, patients' mean visual analogue scale pain score exceeded the range denoting 'analgesic success', and showed considerable exacerbation in the evening. Patients' pain decreased to a mean score of 15.4 one hour after administration of a nonsteroidal anti-inflammatory drug (metamizole).

CONCLUSION

Analgesia is recommended for all patients in the first 3 days after septorhinoplasty, especially in the early evening.

Sex, gender, and pain: a review of recent clinical and experimental findings

Sex-related influences on pain and analgesia have become a topic of tremendous scientific and clinical interest, especially in the last 10 to 15 years. Members of our research group published reviews of this literature more than a decade ago, and the intervening time period has witnessed robust growth in research regarding sex, gender, and pain. Therefore, it seems timely to revisit this literature. Abundant evidence from recent epidemiologic studies clearly demonstrates that women are at substantially greater risk for many clinical pain conditions, and there is some suggestion that postoperative and procedural pain may be more severe among women than men. Consistent with our previous reviews, current human findings regarding sex differences in experimental pain indicate greater pain sensitivity among females compared with males for most pain modalities, including more recently implemented clinically relevant pain models such as temporal summation of pain and intramuscular injection of algesic substances. The evidence regarding sex differences in laboratory measures of endogenous pain modulation is mixed, as are findings from studies using functional brain imaging to ascertain sex differences in pain-related cerebral activation. Also inconsistent are findings regarding sex differences in responses to pharmacologic and non-pharmacologic pain treatments. The article concludes with a discussion of potential biopsychosocial mechanisms that may underlie sex differences in pain, and considerations for future research are discussed.

PERSPECTIVE

This article reviews the recent literature regarding sex, gender, and pain. The growing body of evidence that has accumulated in the past 10 to 15 years continues to indicate substantial sex differences in clinical and experimental pain responses, and some evidence suggests that pain treatment responses may differ for women versus men.

Sex differences in micro-opioid receptor expression in the rat midbrain periaqueductal gray are essential for eliciting sex differences in morphine analgesia

Opioid-based narcotics are the most widely prescribed therapeutic agent for the alleviation of persistent pain; however, it is becoming increasingly clear that morphine is significantly less potent in women compared with men. Morphine primarily binds to mu-opioid receptors (MORs), and the periaqueductal gray (PAG) contains a dense population of MOR-expressing neurons. Via its descending projections to the rostral ventromedial medulla and the dorsal horn of the spinal cord, the PAG is considered an essential neural substrate for opioid-based analgesia. We hypothesized that MOR expression in the PAG was sexually dimorphic, and that these sex differences contribute to the observed sex differences in morphine potency. Using immunohistochemistry, we report that males had a significantly higher expression of MOR in the ventrolateral PAG compared with cycling females, whereas the lowest level of expression was observed in proestrus females. CFA-induced inflammatory pain produced thermal hyperalgesia in both males and females that was significantly reversed in males with a microinjection of morphine into the ventrolateral PAG; this effect was significantly greater than that observed in proestrus and estrus females. Selective lesions of MOR-expressing neurons in the ventrolateral PAG resulted in a significant reduction in the effects of systemic morphine in males only, and this reduction was positively correlated with the level of MOR expression in the ventrolateral PAG. Together, these results provide a mechanism for sex differences in morphine potency.