Sufentanil: clinical use as postoperative analgesic--epidural/intrathecal route

Multimodal Analgesia Bundle and Postoperative Opioid Use Among Patients Undergoing Colorectal Surgery

Importance

A key objective in contemporary surgery is to reduce or eliminate the usage of opioids to minimize gastrointestinal adverse effects, fatigue, and long-term opioid dependency.

Objectives

To evaluate the association of the implementation of a care bundle of 3 opioid-sparing interventions with the amount of opioids consumed postoperatively among patients undergoing major abdominal surgery and to examine the respective associations of the 3 components.

Design, Setting, and Participants

This retrospective cohort study was performed at Ersta Hospital, an elective teaching hospital in Stockholm, Sweden. All patients undergoing major colorectal surgery between January 1, 2016, through December 31, 2019, were included. Data analysis was conducted from February 1, 2020, to May 30, 2022.

Exposures

A care bundle consisting of an individualized opioid regimen, regular gabapentinoids, and clonidine as a rescue analgesic was gradually introduced early in the study period.

Main Outcomes and Measures

Amount of in-hospital administered intravenous and oral opioids on the day of surgery and the first 5 postoperative days (morphine milligram equivalents [MME]). The association between exposure and outcome was examined using multivariable linear regression.

Results

Overall, 842 patients had major colorectal surgery in the study period (mean [SD] age, 64.6 [15.5] years; 421 [50%] men). Median (range) opioid usage decreased from 75 (0-796) MME in 2016 to 22 (0-362) MME in 2019 (P < .001), and the proportion of patients receiving 45 MME or less increased from 35% to 66% (P < .001). On multivariable analysis (F5, 836 = 57.5; P < .001), an individualized opioid strategy (β = -11.6; SE = 3.8; P = .003), the use of gabapentin (β = -39.1; SE = 4.5; P < .001), and increasing age (β = -1.0; SE = 0.11; P < .001) were associated with less opioid consumption, while the use of clonidine was associated with more opioid intake (β = 11.6; SE = 3.6; P = .001).

Conclusions and Relevance

In this cohort study of 842 patients undergoing colorectal surgery, a care bundle consisting of an individualized opioid regimen, regular gabapentin, and clonidine as a rescue analgesic was found to be associated with a significant decrease in opioids consumed postoperatively. Regular gabapentin and an individualized opioid regimen were particularly strongly associated with this decrease and should be further evaluated as components of multimodal, opioid-free postoperative analgesia.

Stability of Morphine Sulfate-Clonidine and Sufentanil-Clonidine Mixtures

BACKGROUND

Spinal analgesia is recommended for intractable cancer pain. Morphine-clonidine and sufentanil-clonidine are often used in association in intrathecal drug delivery systems, injected by intraabdominal pumps. To refill these pumps and to limit patient transport, it may be necessary to ship the mixtures in polypropylene syringes to peripheral establishments located near patient homes. The purpose of this study is to determine the stability of morphine-clonidine and sufentanil-clonidine mixtures in polypropylene syringes to ensure the best and safest transport conditions and in implantable pumps for intrathecal use.

MATERIALS AND METHODS

The stability study method was conceived according to the International Council for Harmonization guidelines. For polypropylene syringes, four different mixtures of morphine-clonidine and sufentanil-clonidine were assessed over seven days. Two storage temperatures were tested (5 ± 3 °C and 25 ± 2 °C). For implantable pumps, two different mixtures of morphine-clonidine and sufentanil-clonidine were assessed over 28 days and stored at 37 °C.

RESULTS

For the morphine-clonidine mixtures in polypropylene syringes, all mixtures remained stable for five days in both storage conditions (5 ± 3 °C and 25 ± 2 °C) because of relative concentrations systematically positioned between 90% and 110% (95% CIs of the mean of three samples). The two mixtures in implantable pumps remained stable for 28 days. For the sufentanil-clonidine mixtures in polypropylene syringes, cold conservation kept all the preparations stable for seven days, whereas a quick degradation was observed after only two days for ambient storage conditions. This result is similar to that with an implantable pump, in which the concentration is <90% on day 7 for low concentration mixtures. No visual modification, no significant pH modification, and no changes in turbidity assays were observed in either study.

CONCLUSION

This study shows the stability of the morphine-clonidine mixtures in syringes stored at 5 °C for five days and in implantable pumps stored at 37 °C for 28 days. For the sufentanil-clonidine mixtures, the results show stability in syringes for seven days at 5 °C. Pump results show stability of seven days for low concentrations and 28 days for high concentrations.

Epidural Oxycodone for Acute Pain

Epidural analgesia is commonly used in labour analgesia and in postoperative pain after major surgery. It is highly effective in severe acute pain, has minimal effects on foetus and newborn, may reduce postoperative complications, and enhance patient satisfaction. In epidural analgesia, low concentrations of local anaesthetics are combined with opioids. Two opioids, morphine and sufentanil, have been approved for epidural use, but there is an interest in evaluating other opioids as well. Oxycodone is one of the most commonly used opioids in acute pain management. However, data on its use in epidural analgesia are sparse. In this narrative review, we describe the preclinical and clinical data on epidural oxycodone. Early data from the 1990s suggested that the epidural administration of oxycodone may not offer any meaningful benefits over intravenous administration, but more recent clinical data show that oxycodone has advantageous pharmacokinetics after epidural administration and that epidural administration is more efficacious than intravenous administration. Further studies are needed on the safety and efficacy of continuous epidural oxycodone administration and its use in epidural admixture.

Gas Chromatography-Mass Spectrometry Analysis of Synthetic Opioids Belonging to the Fentanyl Class: A Review

The rising number of deaths caused by fentanyl overdosing in the US due to the overwhelming illicit use of this synthetic opioid has started a global campaign to develop efficient ways to control its production and distribution as well as discovering efficient antidotes to mitigate its lethal effects. Another important vein of focused research established by various agencies lies in the development of efficient and practical protocols for the detection of this opioid and analogs thereof in various matrices, whether environmental or biological in nature, particularly in the field of gas chromatography-mass spectrometry (GC-MS). The following review will cover the literature dealing with the detection and identification of synthetic opioids belonging to the fentanyl class by GC-MS means and hyphenated versions of the technique. Detailed descriptions will be given for the GC-MS methods employed for the analysis of the opioid, starting with the nature of the extraction protocol employed prior to analysis to the actual findings presented by the cited reports. Great effort has gone into describing the methods involved in each paper in a detailed manner and these have been compiled by year in tables at the end of each section for the reader's convenience. Lastly, the review will end with concluding remarks about the state of GC-MS analysis with regards to these powerful opioids and what lies ahead for this analytical field.

Mitochondrial biogenesis factor PGC-1α suppresses spinal morphine tolerance by reducing mitochondrial superoxide

Opioid use disorders (OUDs) have reached an epidemic level in the United States. The opioid epidemic involves illicit opioid use, prescription opioids for analgesia, counterfeit opioids, new psychoactive substances, and diverted opioids. Opioids remain the last option for the treatment of intractable clinical pain, but chronic use of opioids are limited in part due to antinociceptive/analgesic tolerance. Peroxisome proliferator-activated receptor (PPAR)-gamma coactivator-1alpha (PGC-1α), a mitochondrial biogenesis factor can reduce toxic reactive oxygen species (ROS) that play a role in morphine tolerance (MT). Decreased PGC-1α expression has been shown to contribute to various metabolic disorders or neurodegeneration diseases through increasing ROS. We examined the relationship of PGC-1α and ROS in MT. To induce MT, adult Sprague-Dawley rats received intrathecal morphine for 7 days. Mechanical threshold was measured using the von Frey test and thermal latency was examined using the heat plate test. Expression of PGC-1α in the spinal cord dorsal horn (SCDH) was examined using RT-PCR and western blots. Mitochondrial superoxide was detected using MitoSox Red, a mitochondrial superoxide indicator. The antinociceptive effect of recombinant PGC-1α (rPGC-1α) or Mito-Tempol (a mitochondria-targeted superoxide scavenger) was determined using the von Frey test and hot plate test. Furthermore, we examined the effect of rPGC-1α on mitochondrial superoxide using cultured neurons. Our findings include that: (i) spinal MT decreased the expression of spinal PGC-1α in the SCDH neurons; (ii) rPGC-1α increased mechanical threshold and thermal latency in MT animals; (iii) Mito-Tempol reduced MT behavioral response; (iv) rPGC-1α reduced MT-induced mitochondria-targeted superoxide; and (v) cultured neuronal cells treated with TNFα increased mitochondria-targeted superoxide that can be inhibited by rPGC-1α. The present findings suggest that spinal PGC-1α reduce MT through decreasing mitochondria-targeted superoxide in the SCDH.

Flip-Flop Phenomenon in Epidural Sufentanil Pharmacokinetics: A Population Study in Children and Infants

The aims of this study were to develop a population pharmacokinetic model of sufentanil coadministered with 0.2% ropivacaine as an epidural infusion in infants and describe the sufentanil absorption profile from epidural space. Data from 2 previously published studies were merged for analysis-20 infants aged 3-36 months receiving sufentanil as an epidural infusion and 41 children 0-17 years old receiving sufentanil as a long-term intravenous infusion. A population nonlinear mixed-effects model was built in NONMEM. Sufentanil pharmacokinetics were described by a 2-compartment model with first-order absorption. The effect of body size on all volume and clearance parameters was included in the model according to allometric scaling with theoretical exponents. The maturation process of metabolic clearance was described by the Hill model. During the model-building process the population was divided into 2 fractions with different typical values of metabolic clearance (CL1 and CL2). The typical values of systemic clearance scaled to a 70-kg patient for the 2 subpopulations were CL1 = 52.6 L/h and CL2 = 158 L/h. The parameters of the Hill function were 54.9 weeks for the postmenstrual age of 50% clearance maturation and 0.802 for the Hill coefficient. The typical values of distribution clearance and volumes of the central and peripheral compartments for a patient with a weight of 70 kg were Q = 40.5 L/h, VC = 7.63 L, and VT = 473 L, respectively. The value of the absorption rate constant from the epidural space was 0.0459/h, which suggests flip-flop pharmacokinetics of sufentanil after epidural administration.

Thoracic Epidural Analgesia

Thoracic epidural analgesia (TEA) offers a unique oppor tunity for the anesthesiologist to enhance postopera tive recovery for the thoracic surgery patient. By deliver ing analgesics to a limited dermatomal distribution, TEA can provide profound segmental analgesia and also serves to modulate neural outflow to improve cardiac and pulmonary parameters. The notable side-effects of hypotension and respiratory depression can be mini mized by using synergistic combinations of local anes thetic and opioids, and by adopting a continuous infu sion strategy. With thoughtful patient selection, careful technique, and a proactive approach to the recognition of the known hemodynamic and respiratory effects of epidural drugs, TEA can be administered safely. The significant benefits of TEA include better pain relief, increased FEV1, earlier extubation, and, perhaps, de creased morbidity and mortality.

An efficient, optimized synthesis of fentanyl and related analogs

The alternate and optimized syntheses of the parent opioid fentanyl and its analogs are described. The routes presented exhibit high-yielding transformations leading to these powerful analgesics after optimization studies were carried out for each synthetic step. The general three-step strategy produced a panel of four fentanyls in excellent yields (73–78%) along with their more commonly encountered hydrochloride and citric acid salts. The following strategy offers the opportunity for the gram-scale, efficient production of this interesting class of opioid alkaloids.

Adjuvants in pediatric regional anesthesia

SUMMARY Local anesthetics have a limited duration of action. Adjuvants are used to prolong the duration of action and to augment analgesia allowing lower concentrations of local anesthetic to be used. Adjuvants have been used more extensively with neuraxial blocks, particularly caudal epidural blocks, but more recently to supplement peripheral nerve blocks. Intrathecal adjuvants are not covered in this review since spinal anesthesia is not widely used in children except in ex-premature infants. Morphine is the historical gold-standard with which other adjuvants are compared. Clonidine is most useful and is becoming increasingly popular, while the side-effect profile of other agents reduces their utility. Concerns with regard to the neurotoxicity of ketamine in animal models has led to its withdrawal in some countries.

Postoperative analgesia with epidural opioids after cesarean section: Comparison of sufentanil, morphine and sufentanil-morphine combination

Background:

Epidural analgesia with opioid provides good control of postoperative pain in cesarean section, thereby improving the mother's ability to mobilize and interact with her newborn infant.

Aim:

The aim of this study is to evaluate and compare the analgesic actions and side effects of epidural analgesia with sufentanil, morphine or combination of the two after cesarean section.

Materials and Methods:

60 women undergoing elective cesarean section were allocated into three groups of 20 each in a randomized blinded fashion. Epidural analgesia was administered with sufentanil 50 mcg in Group S; morphine 4 mg in Group M; and, a combination of sufentanil 25 mcg and morphine 2 mg was used in Group SM. Analgesic efficacy in terms of onset of action and duration of analgesia was assessed by using the Visual Analog Scale (0 to 10 cm) for 24 hours. Number of opioid doses needed in 24 hours was noted. Side effects like respiratory depression /excessive sedation, pruritus and nausea were recorded.

Results:

Onset of action were at 7.6 ± 1.5 minutes in group S, 67.6 ± 1.5 minutes in group M and 12.2 ± 2.6 minutes in group SM. Duration of analgesia was longer in group M 17.5 ± 1.9 hours and SM 13.8 ± 1.6 hours than in group S 5.2 ± 1.2 hours. More doses of analgesia were required in group S compared to group M and SM. Side effects were comparable in the three groups.

Conclusion:

Epidural administration of a combination of sufentanil and morphine offered the advantage of faster onset of action and longer duration of analgesia as compared to the two drugs administered alone.

Intrathecal sufentanil for intraoperative and postesophagectomy pain relief

OBJECTIVES

The present study compares the analgesic properties of intrathecal (IT group) and intravenous (IV group) sufentanil in postoperative pain relief.

METHODS

This randomized, single blinded study was performed on patients awaiting transhiatal esophagectomy. The patients were randomly allocated to receive sufentanil intrathecally or intravenously. Sufentanil consumption during the operation, pain score following the operation based on visual analog scale (VAS) and the morphine requirement for postoperative analgesia were assessed during the first 24 hours.

RESULTS

Fifty patients were divided in two groups. During the operation, the opioid requirement was higher in the IV group, whereas the morphine requirement during the first 24 hours after the operation was the same in both groups. The duration of effective postoperative analgesia was longer in patients in the IT group. VAS pain scores were significantly lower during the first 2 hours postoperatively in the IT group. The incidence of side effects such as nausea, vomiting, headache and respiratory depression was infrequent in both groups.

CONCLUSIONS

Preoperative IT sufentanil can be used as a booster to achieve rapid and effective analgesia not only during the operation but also during the immediate postoperative period.

Epidural naloxone reduces postoperative nausea and vomiting in patients receiving epidural sufentanil for postoperative analgesia

BACKGROUND

Epidural opioids have excellent analgesic properties, but their side-effects limit their use in patient-controlled epidural analgesia. This study was designed to evaluate the effect of epidural naloxone on the side-effects of sufentanil, focusing on postoperative nausea and vomiting (PONV) in patients undergoing total knee replacement (TKR).

METHODS

After obtaining Institutional Review Board approval and informed consent, 50 patients undergoing unilateral TKR were randomly assigned to receive either sufentanil in ropivacaine alone (Group C, n = 25) or the same solution with naloxone (Group N, n = 25) for their postoperative epidural analgesia. Episodes of PONV and five-point-scaled nausea scores were evaluated at 6, 12, and 24 h after epidural analgesia was started. Visual analogue scale (VAS) score for pain and the incidence of sedation, pruritus, hypotension, and respiratory depression were also evaluated at each of three time points.

RESULTS

The nausea score in Group N was significantly lower than that in Group C. The VAS pain score at rest and on movement were significantly lower in Group N than in Group C at 24 h. Other opioid-induced side-effects were not significantly different.

CONCLUSIONS

Epidural naloxone was effective in reducing PONV induced by epidural sufentanil and additionally enhanced the analgesic effect. Therefore, concomitant infusion of a small dose of epidural naloxone should be considered to reduce PONV, especially in patients at greater risk for PONV.

A randomized, double-blinded comparison of intrathecal morphine, sufentanil and their combination versus IV morphine patient-controlled analgesia for postthoracotomy pain

We compared the analgesic effect of lumbar intrathecal (IT) 0.5 mg morphine (Group M, n = 10), 50 microg sufentanil (Group S, n = 10), and their combination (Group S-M, n = 10) given before general anesthesia and patient-controlled analgesia with IV morphine (Group C, n = 19) in a randomized, double-blinded study performed in patients undergoing thoracotomy. Pain visual analog scale (VAS) and morphine consumption were assessed for 24 h. In Group S-M the number of patients initially titrated with IV morphine was less than in group C (30 vs 84%, P < 0.05). Morphine requirement was higher in Group C (71 +/- 30 mg) than in Groups S (46 +/- 34 mg, P < 0.05), M (38 +/- 31 mg, P < 0.05) and S-M (23 +/- 16 mg, P < 0.01). VAS scores were significantly decreased during the first 0-11 postoperative h at rest and during the first 0-8 postoperative h on coughing in Groups M and S-M rather than in Group C. The incidence of side effects was infrequent except for urinary retention. Preoperative IT morphine or combined sufentanil and morphine could be given as a booster to achieve rapidly effective analgesia in the immediate postoperative period.

IMPLICATIONS

As compared with IV patient-controlled analgesia, intrathecal morphine or combined sufentanil and morphine provided superior postoperative pain relief both at rest (11 h) and on coughing (8 h) than did IV patient-controlled analgesia morphine alone. IV morphine requirement was decreased during the first postoperative day after posterolateral thoracotomy.

Epidural and spinal agents for postoperative analgesia

The discovery of opioid receptors and the subsequent development of the technique of epidural and intrathecal opioid administration are undoubtedly two of the most significant advances in pain management in recent decades. The use of spinal opioids is widespread and increasing. The technique is used widely to treat intraoperative, postoperative, traumatic, obstetric, chronic, and cancer pain. Newer developments include the increasing use of combined local anesthetics and opioids or nonopioids and also PCEA, particularly in the obstetric population. Meta-analysis of controlled trials has demonstrated improved pulmonary outcome in patients receiving epidural postoperative analgesia. Although rare, respiratory depression continues to be a major problem of the technique. None of the currently available opioids is completely safe; however, extensive international experience has shown that patients receiving spinal opioids for postoperative analgesia can be safely nursed on regular wards, provided that trained personnel and appropriate guidelines are available. The importance of a good acute pain service to provide the safe and effective use of spinal opioids cannot be overemphasized.

Postoperative intrathecal patient-controlled analgesia with bupivacaine, sufentanil or a mixture of both

In a randomised double-blind study, 45 patients, scheduled for major orthopaedic surgery under continuous spinal anaesthesia, received for relief of postoperative pain patient-controlled analgesia with either sufentanil 2 micrograms.ml-1, bupivacaine 0.0625% or a mixture of both by the intrathecal route. The mean (SD) consumption of sufentanil and bupivacaine during the first 12 h was 65.5 (27.1) micrograms and 18.2 (4.8) mg, respectively. Combining bupivacaine and sufentanil reduced the consumption of both to approximately 40% as compared to the administration of each component separately. Pain relief was very good in all subjects, although this was obtained faster with the combined regimen. Moreover, more patients in this group remained completely painfree during the entire observation period (p < 0.05). The incidence of hypotension was low and not significantly different when the plain bupivacaine group was compared with the two other groups. Nausea and vomiting were significantly more frequently observed in both groups treated with sufentanil. Motor block was not a major problem and was noticed during the first 2 h of treatment only. Tachyphylaxis did not occur. It was concluded that the groups receiving plain bupivacaine and sufentanil alone experienced pain relief of good quality. The use of a mixture, however, accelerated the onset of analgesia, improved the analgesic quality and reduced the doses for both components by 60% but at the expense of a higher incidence of nausea and vomiting.

Intrathecal sufentanil, fentanyl, or placebo added to bupivacaine for cesarean section

We compared the effects of intrathecal sufentanil 2.5 and 5 microg, fentanyl 10 microg, and placebo when administered together with hyperbaric bupivacaine 0.5% 12.5 mg for cesarean section. The study was performed in a randomized, double-blind fashion in 80 (20 per group) healthy, full-term parturients presenting for elective cesarean section. Postoperative pain was assessed using the visual analog scale (VAS). Duration of complete analgesia was defined as the time from the intrathecal injection to VAS score > 0. Duration of effective analgesia was defined as the time to VAS score > or = 4. No patient experienced intraoperative pain. Complete analgesia was prolonged in all groups receiving opioids. Effective analgesia was prolonged and the 0- to 6-h intravenous opioid requirements were lower in the groups receiving sufentanil compared with those receiving fentanyl and placebo. The need for intraoperative antiemetic medication was greater in the placebo group. Pruritus was a frequent and dose-related side effect in the groups receiving sufentanil. There were no differences in umbilical cord blood gases or neonatal Apgar scores and neurological and adaptive capacity scores among the groups. In conclusion, the addition of sufentanil or fentanyl improved the quality of subarachnoid block compared with placebo. The duration of action was longer for sufentanil than fentanyl.

IMPLICATIONS

Small doses of fentanyl or sufentanil (synthetic opioids) added to bupivacaine (local anesthetic) for spinal anesthesia for cesarean section reduce the need for intraoperative antiemetic medication and increase the duration of analgesia in the early postoperative period compared with placebo.

Reduced postoperative analgesic demand after inhaled anesthesia in comparison to combined epidural-inhaled anesthesia in patients undergoing abdominal surgery

We studied the effect of epidural/general combination anesthesia, in comparison to inhaled anesthesia, on postoperative pain and analgesic consumption in patients undergoing upper abdominal surgery. Anesthesia was induced with propofol and maintained with enflurane in 70% N2O as necessary to maintain arterial blood pressure within 20% of baseline. Group I received bupivacaine 0.25% 0.2 mL/kg and sufentanil 1 microgram/kg 65 +/- 3 min before dermal incision and 0.1 mL/kg bupivacaine 0.25% + sufentanil 2 micrograms/mL (BS) every hour thereafter. Group II received 0.2 mL/kg of BS 316 +/- 15 min after dermal incision in the recovery room. Postoperative patient-controlled epidural analgesia (PCEA) with BS was provided. Pain intensities and consumption of PCEA BS were recorded on postoperative days (PODs) 1 to 5. Inspiratory fraction of enflurane was lower (0.5% +/- 0.01% vs 1.6% +/- 0.04%; P < 0.001) in Group I compared with Group II. Cumulative postoperative consumption of PCEA BS was higher in Group I compared with Group II from the evening of POD 2 until the end of the study (301 +/- 19 mL vs 249 +/- 17 mL; P < 0.001), while pain intensities were comparable at all times. The intraoperative effects of combined BS and enflurane/N2O (inspiratory fraction [Fi] approximately 1 minimum alveolar anesthetic concentration [MAC]) did not preempt postoperative pain in contrast to enflurane/N2O anesthesia (Fi approximately 2.8 MAC).

Postoperative analgesia with continuous epidural sufentanil and bupivacaine: a prospective study in 614 patients

To assess the efficacy and safety of postoperative analgesia with continuous epidural sufentanil and bupivacaine, we performed a prospective study in 614 patients undergoing major surgery. Before surgical incision, all patients received an initial dose of 50 micrograms sufentanil in 6-10 mL bupivacaine 0.125% via a lumbar or thoracic catheter. After 1 h, a continuous infusion was started with 50 micrograms sufentanil in 50 mL bupivacaine 0.125% at a rate of 6-10 mL/h. The infusion was continued postoperatively for 1-5 days or longer, depending on the type of operation and the patient's analgesic need. In the majority of patients, adequate pain relief was obtained at rest and during movement. Late respiratory depression was observed in three patients; in most patients only minor side effects were seen. Technical complications during epidural puncture or insertion of the catheter were 4% and 3%, respectively. We conclude that continuous epidural sufentanil and bupivacaine is safe and effective.

Pharmacotherapy of opioids: present and future developments

The clinically available opioids have different physicochemical properties, resulting in differences in clinical profile with regard to potency, onset, and duration of activity. However, they all have comparable side-effects after acute systemic application. Several approaches can be used to overcome these side-effects. The following approaches, with special emphasis on the perioperative use of the opioids, are discussed: (1) the use of alternative routes of administration, such as via the spine (epidurally and intrathecally); (2) optimization of opioid delivery by means of slow-release preparations, chronic infusions with indwelling catheters, and transdermal delivery systems; (3) use of additional agents to potentiate the analgesic properties of the opioids so that the dose of opioid can be reduced; and (4) searching for new analgesics on the basis of knowledge of the pain-transmission system and the different opioid receptors with their functional interactions.

Does epidural sufentanil provide effective analgesia per- and postoperatively for abdominal aortic surgery?

To assess the efficacy of epidural sufentanil in providing per- and postoperative analgesia, 40 patients undergoing elective abdominal aortic surgery received either 50 mu g sufentanil in 10 ml normal saline solution (n = 20, ES group) or 10 ml normal saline (n = 20, control group) via a thoracic epidural catheter. The study solution was given (double-blind and at random) after the patients had been anaesthetized with i.v. midazolam, sufentanil and vecuronium. Anaesthesia was maintained with 60% nitrous oxide in oxygen and halothane at a 1% inspiratory concentration. When patients showed signs of inadequate analgesia, supplementary doses of 25 mu g sufentanil were given i.v. The number of patients requiring additional i.v. sufentanil differed significantly between the two groups: 5 out of 20 patients in the ES group vs 13 out of 20 patients in the control group required additional sufentanil (P<0.05). The mean dose administered i.v. did not differ significantly between the two groups: 105 +/- 109.5 mu g vs 138.5 +/- 126.9 mu g (mean +/- SD) in 5 and 13 patients, respectively. No cardiovascular changes were observed after the epidural bolus dose. Postoperative analgesia, consisting of a continuous epidural infusion of 50 mu g sufentanil in 50 ml bupivacaine 0.125% at a rate of 6-10 ml/h after a bolus dose of 10 ml of this solution, was adequate in the majority of patients, as determined by VAS-scores assessed during the epidural treatment (4.3 +/- 1.5 days).

Interactions between the lipophilic opioid sufentanil and clonidine in rats after spinal application

BACKGROUND

Alpha2-adrenoceptor agonists, such as clonidine, can potentiate the analgesic properties of spinal opioids. In order to further extend this observation to highly lipophilic and potent spinally acting opioids, we tested the interactions between clonidine and sufentanil after both epidural and intrathecal administration in rats.

METHODS

The rats were equipped with spinal catheters. Antinociceptive testing was performed with the Tail Withdrawal Reaction test. Dose-response functions of sufentanil, clonidine and combinations of clonidine plus sufentanil were determined.

RESULTS

These indicated that 1) sufentanil, but not clonidine alone, results in a dose-related antinociception after both the epidural and the intrathecal route of administration; 2) In combination with normally inactive doses of sufentanil, the addition of clonidine results in activity; 3) In a particular dose-range of sufentanil, there is a direct relationship between the doses of sufentanil and clonidine needed to produce antinociception; 4) Even at very high doses of clonidine, a minimal amount of sufentanil is needed to produce antinociception and 5) At the conditions tested here, the contribution of clonidine is minimal at high, intrinsic active doses of sufentanil.

Thoracic epidural anaesthesia in infants and children

When compared with conventional analgesic techniques, epidural anaesthesia not only provides improved analgesia, but also has several beneficial effects on the postoperative respiratory, cardiovascular, and metabolic status of the patient. Although the efficacy and safety of caudal and lumbar epidural anaesthesia in children has been demonstrated, there is little information concerning the use of thoracic epidural anaesthesia. The purpose of our review was to evaluate the safety of thoracic epidural anaesthesia in infants and children. We retrospectively reviewed our three-year experience with thoracic epidural anaesthesia for postoperative analgesia in children. Epidural catheters were placed at the thoracic level without difficulty in 63 children ranging in age from three months to 18 yr and in weight from 3.2 to 78 kg. Postoperative analgesia was provided by the continuous infusion of a bupivacaine/fentanyl mixture, supplemented with intermittent epidural fentanyl by bolus as needed. Epidural catheters were successfully placed in all patients. No inadvertent dural punctures were noted. No episodes of respiratory depression related to epidural analgesia occurred. Minor adverse effects including pruritus occurred in six patients, three of whom required pharmacological intervention with diphenhydramine. Our review suggests that this is a safe and effective method of postoperative analgesia following thoracic surgery in children.