Pruritus after continuous administration of epidural morphine for post-cesarean delivery analgesia: a case control study

Background Pruritus is one of the most common side effects of epidural morphine administered for post-surgery analgesia, and pregnant women tend to be highly susceptible. The relative contributions of morphine concentration, local anesthetics, and level of pain to pruritus after epidural morphine for post-cesarean delivery analgesia remain unclear. Accordingly, the present study aimed to identify risk factors for pruritus after continuous administration of epidural morphine for post-cesarean delivery analgesia. Methods This case control study was based on routinely collected clinical data. Participants included women who had undergone cesarean section and adopted a patient-controlled analgesia pump for postoperative analgesia. A series of logistic regression analyses were performed. Interaction terms were added to explore the moderation effects of combined local anesthetics and pain level on associations between morphine concentration and pruritus. Robustness of the results was checked through sensitivity analysis using propensity scores matching approach. Results Higher morphine concentration, assisted reproductive treatment, and multipara and cesarean section history were significantly more prevalent in the pruritus group than in the control group. The probabilities of pruritus at morphine concentrations of 10, 15, 20, 25, 30 and 40 μg/mL increased sequentially from 0.05, 0.1, 0.2, 0.35, 0.54 to 0.84, respectively. The trend remained steep in the ropivacaine stratum and became flatter when combined with levobupivacaine. At mild pain combined with levobupivacaine, the incidence of pruritus increased from 0.33 (95% confidence interval [CI] 0.1–0.68) in the 10 μg/mL morphine group to 0.48 (95% CI 0.1–0.88) in the 40 μg/mL morphine group. In the stratum of moderate pain combined with levobupivacaine, the incidence increased from 0.4 (95% CI 0.04–0.92) to 0.56 (95% CI 0.03–0.98). The results in the sensitivity analysis were in consistent with above findings. Conclusions Higher concentrations of morphine, multipara, and assisted reproductive treatment were factors associated with a higher probability of pruritus. Pain level or combined local anesthetics could moderate the association between morphine concentration and pruritus.

The effect of morphine on the development rate of flies (Diptera: Calliphoridae, Sarcophagidae) reared on rabbit carcasses containing this drug and its implications to postmortem interval estimates

Insects can prove to be a valuable tool in the estimation of PMI in the investigation of homicides, suicides, and other unattended human deaths, in the absence of tissues and body fluids. Aim: The current study aimed to determine morphine concentration in the second, third feeding, third post-feeding instars, and puparial skin of four forensically important flies; Lucilia sericata (Meigen), Chrysomya albiceps (Wiedemann), Chrysomya megacephala (Fabricius) (Calliphoridae), and Sarcophaga argyrostoma (Robineau-Desvoidy) (Sarcophagidae) and to evaluate its effect on the rate and pattern of development of these flies. Materials and methods: Three female domestic rabbits, Oryctolagus cuniculus (L.) each weighing 2.5 kg received dosages of 7.5, 15, and 30 mg of morphine over a 3-h period via left ear artery perfusion. For each trial, one other rabbit, weighing 2.5 kg, was used as a control. Morphine was detected in larval instars and puparial skin using ready to use RIA kit. Results: All blood and tissue samples obtained from the rabbits receiving dosages of morphine were positive for the drug. Morphine concentrations for rabbit R2 were 1.2 to 2.6 times greater than those for rabbit R1, and concentrations for rabbit R3 were 1.4 to 3.1 times greater than those for rabbit R2. For each rabbit, morphine concentration in second, third feeding and third post-feeding instars, and puparial skin for all four species, were less than those detected in the tissues. The highest levels of morphine were recorded in the feeding third instars of Chr. megacephala R3 colony, whereas the lowest level of this drug was detected in the feeding third instars of S. argyrostoma R1 colony. Estimations of larval age for L. sericata, Chr. albiceps, Chr. megacephala and S. argyrostoma based on mean length can be significantly in error if presence of morphine in the tissues is not considered. This error can be as great as 24, 27, 6 and 21 h respectively. Conclusion: In cases of badly decomposed and/or skeletonized remains, analyses of collected carrion-feeding insects, may provide the most accurate qualitative sources of toxicological information.