A Randomized Double-Blind Comparison of Epidural Versus Intravenous Fentanyl Infusion for Analgesia After Cesarean Section

Spinal Opioid Bioavailability in Postoperative Pain

“…10, 23,43 Recently, evidence has emerged that single doses prior to surgery in the form of extended-release liposomal injections in the lumbar region, with no need to place an epidural catheter, reliably provide good, long-lasting (up to 48 hours) analgesia, with reasonable levels of tolerance for side effects. [44][45][46]67 Clinical trials have also shown that the administration of lipophilic opioids by continuous epidural infusion does not cause analgesia by direct spinal action [48][49][50][51][52][53][54][55][56][57][58][59][60] (in contrast to epidural bolus injections of fentanyl, where sufficient concentrations of the drug can reach the spinal site of action 61 ). On the other hand, the addition of opioids, including lipophilic opioids, may enable a reduction in the dose of LA and a commensurate reduction in LArelated side effects.…”

“…Clinical trials have demonstrated that hydrophilic opioids like morphine, 9,10 especially when given as a continuous infusion plus LA, 23,43 or by extended-release epidural injections, [44][45][46] provide good postoperative analgesia but are associated with a relatively high rate of adverse effects. 47 Most of the analgesic effect of epidural lipophilic opioids such as fentanyl, [48][49][50][51][52] sufentanil, [53][54][55][56] and alfentanil [57][58][59] is due to systemic uptake. When given alone, the epidural route does not seem to offer advantages over parenteral administration.…”

“…This is particularly true for sufentanil. Systemic analgesia can be used at a 1000-fold lower dose than morphine (10 lg vs. 10 mg); however, in the case of intrathecal administration, the 64,65 High High Methadone (116) 62, 63 Moderate Moderate Fentanyl (955) [48][49][50][51][52]60,66,68 Low as continuous infusion Moderate as a bolus Moderate Sufentanil (1737) [53][54][55][56]66 Low Moderate Alfentanil (129) [57][58][59] Very low Very low *Into brackets opioid liposolubility in relation to morphine, expressed as octanol/buffer distribution coefficient. 23 difference is only 10-fold (10 lg vs. 100 lg), which leads one to suspect a low bioavailability at the spinal cord.…”

Epidural vs. intravenous fentanyl during colorectal surgery using a double‐blind, double‐dummy design

“…Median time [IQR (range)] to awakening ( Fig. 3) was 8 min [4.5 (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)] in the epidural group and 20 min [12.5 (7-34)] in the intravenous group (P < 0.001); the ANCOVA model rules out the possibility that the differences were related to the dose of propofol. When evaluating the time to analgesia request ( Fig.…”

“…1 Many authors hold that epidural administration of fentanyl is more effective than intravenous administration, suggesting a spinal site of action; [2][3][4][5][6] others claim that both routes of administration provide a similar degree of analgesia, suggesting a supraspinal site of action after vascular absorption from the epidural space and redistribution from there to the brain. [7][8][9][10] If the latter hypothesis is correct, epidural fentanyl should provide no benefit over systemic (i.e. intravenous) administration.…”