Optimal dose of intrathecal clonidine added to sufentanil plus bupivacaine for labour analgesia

A Comparative Study of Intrathecal Bupivacaine and Bupivacaine with Different Doses of Clonidine in Lower Limb Surgeries

Background:

Intrathecal clonidine is a very safe, nonopioid adjuvant to local anesthetics to prolong the duration of analgesia without any major side effects.

Objective:

The purpose of the present study was to evaluate the efficacy of clonidine in two different doses as an adjuvant to bupivacaine intrathecally in lower limb surgeries.

Materials and Methods:

A total of 75 adult patients scheduled to undergo lower limb surgeries were randomly allocated into either of three groups of 25 patients. Group I received 12.5 mg bupivacaine, Group II patients received bupivacaine 12.5 mg with clonidine 15 μg, and patients in Group III received bupivacaine 12.5 mg with clonidine 30 μg intrathecally. A total volume of 3 ml was made in all groups using normal saline. The hemodynamic parameters, onset, and duration of sensory block, highest dermatomal level of sensory block, motor block onset, time to complete motor block recovery, and mean time to request of the first analgesic were recorded. Side effects or any other complications were noted.

Results:

The mean time of onset of sensory block and motor block was less in clonidine groups. The mean duration of sensory block was significantly prolonged in clonidine groups as compared to study group. The duration of motor block (in minutes) was significantly prolonged in Group III (171.60 ± 38.20) as compared to Group I (113.20 ± 35.79) and Group II (115.20 ± 38.41). The time of analgesic request in Group I was 148.16 ± 43.99 min, 190.60 ± 38.08 in Group II, and 200.80 ± 59.85 min in Group III.

Conclusions:

The addition of intrathecal clonidine 15 μg to small dose bupivacaine increased the spread, duration of analgesia, and produced effective spinal anesthesia with stable hemodynamics and did not prolong postoperative motor block.

Optimal Dose of Epidural Dexmedetomidine Added to Ropivacaine for Epidural Labor Analgesia: A Pilot Study

Background

Dexmedetomidine combined with local anesthetics can decrease the concentration of epidural ropivacaine. However, the optimal dose of epidural dexmedetomidine combined with ropivacaine for labor analgesia is still uncertain. This study investigated the effect of adding different dose of epidural dexmedetomidine to ropivacaine during epidural labor analgesia.

Methods

One hundred women were randomly assigned to one of the four groups (Groups A, B, C, and D received 0.25, 0.5, 0.75, and 1 μg/ml of dexmedetomidine plus 0.1% ropivacaine, resp.). The onset of epidural anesthesia and stages of labor were studied, and pain was assessed using a visual analogue scale (VAS). Hemodynamic parameters and fetal heart rate were monitored. Apgar scores and umbilical artery pH were recorded. The side effects, if any, were recorded also.

Results

The addition of 0.25, 0.5, and 0.75 μg/ml of dexmedetomidine to 0.1% ropivacaine provided safe and effective analgesia, but 1 μg/ml of dexmedetomidine resulted in increasing incidence of motor block. The hemodynamic parameters were similar between groups (P > 0.05). Side effects in Group D were significantly higher than those in the other three groups (P < 0.05).

Conclusions

When dexmedetomidine is combined with 0.1% ropivacaine, the optimal concentration of dexmedetomidine is 0.5 μg/ml for epidural labor analgesia (this trial is registered with ChiCTR-OPC-16008548).

Comparative evaluation of dexmedetomidine and clonidine with low dose ropivacaine in cervical epidural anesthesia for modified radical mastectomy: A prospective randomized, double-blind study

CONTEXT

Alpha-2 adrenergic agonists clonidine and dexmedetomidine, are well known to produce analgesia through an opioid independent mechanism. Alpha-2 agonists are used as an adjuvant to local anesthetic agents to extend the duration of spinal, epidural and brachial plexus blocks.

AIMS

We compared clonidine and dexmedetomidine as an adjuvant to Ropivacaine in cervical epidural anesthesia (CEA) with respect to onset and duration of sensory block, duration of analgesia and adverse effects.

SUBJECTS AND METHODS

A total 150 American Society of Anesthesiologists Class I or II adult female patients who were scheduled to undergo modified radical mastectomy were randomly allocated to the following two groups to receive CEA: Group D receive 15 mL of 0.375% ropivacaine combined with 1 μg/kg of dexmedetomidine; Group C received 15 mL of 0.375% ropivacaine combined with 1.5 μg/kg of clonidine. The onset of sensory block, duration of analgesia, mean arterial pressure (MAP), heart rate (HR), sedation scores, and the incidences of adverse effects, such as hypotension, bradycardia, and oxygen desaturation were recorded.

RESULTS

The addition of dexmedetomidine to ropivacaine (Group D) resulted in faster onset of sensory block time compared with the addition of clonidine to ropivacaine (Group C) (95% confidence interval [CI]: 14.53 ± 2.96 vs. 16.72 ± 4.43 P = 0.032). The duration of analgesia block in Group D was significantly longer than that in Group C (95% CI: 234.65 ± 23.76 vs. 286.76 ± 34.65; P = 0.037). The Ramsay sedation score at in Group D were significantly higher between 20 and 60 min as compared to Group C (P < 0.022). MAP level and HR level in Group D and Group C were comparable.

CONCLUSION

The addition of dexmedetomidine to low dose ropivacaine for CEA could shorten the onset of sensory block and extend the duration of analgesia with optimum sedation without episodes of hypoxemia as compared to addition of clonidine to ropivacaine.

Effect of intrathecal clonidine versus fentanyl on bupivacaine spinal block in transurethral resection of prostate surgeries

Aims:

Our study aimed at comparing the onset, degree and recovery time of sensory and motor block, the hemodynamic effects and postoperative pain relief using intrathecal bupivacaine alone, bupivacaine along with fentanyl and clonidine.

Materials and Methods:

A total of 90 patients, undergoing transurethral resection of prostate (TURP) surgeries under spinal anesthesia were studied. Patients were randomly divided in a double-blind manner into three groups of 30 patients each. Group A (control) patients given subarachnoid block with 0.5% hyperbaric bupivacaine with 0.5 ml of normal saline. Group B patients were given subarachnoid block with 0.5% hyperbaric bupivacaine along with fentanyl 25 μg. Group C patients were given subarachnoid block with 0.5% hyperbaric bupivacaine 10 mg along with clonidine 30 μg and 0.3 ml of normal saline. After administering the subarachnoid block, vitals were recorded before and after surgery. Level of sensory block, the duration of motor block (DOMB), duration of sensory blockade (DOSB), the quality of postoperative analgesia using linear visual analog scale (VAS), and side effects were evaluated.

Results:

The time required to attain a maximum height of the block was significantly more in Group B as compared to Groups A and C, which was statistically significant. However, there was no statistically significant difference between Groups A and C. The mean DOSB in Groups A, B, and C were 90.83 ± 9.48 min, 135.33 ± 12.59 min, and 155.17 ± 17.49 min, respectively. The mean DOMB in Groups A, B, and C were 83.83 ± 6.52 min, 115.50 ± 14.70 min and 120.67 ± 11.50, respectively. Time of the first request of analgesia in Groups A, B and C in postoperative period were 132.50 ± 21.53 min, 296.00 ± 50.07 min, and 311.83 ± 65.34 min. patients had. VAS was significantly of higher value in Group A than Groups B and C.

Conclusions:

Intrathecal clonidine in a combination of bupivacaine for TURP provides more satisfactory anesthesia and analgesia and has less side effects.

Low dose intrathecal clonidine and fentanyl added to hyperbaric bupivacaine prolongs analgesia in gynecological surgery

Background:

We undertook this study to ascertain if a small dose of clonidine (30 μg) when added to a bupivacaine-fentanyl mixture improves spinal analgesia, without producing side effects, as compared to a bupivacaine-fentanyl or a bupivacaine-clonidine mixture.

Materials and Methods:

In this prospective, randomized, double-blind study, 75 (American Society of Anesthesiologists) ASA grade I-II patients, aged between 45 and 65 years, who were scheduled for vaginal hysterectomy with pelvic floor repair or non-descent vaginal hysterectomy under spinal anesthesia were recruited. The patients received hyperbaric bupivacaine (2.3 ml) with fentanyl 15 μg (Group BF) or clonidine 30 μg (Group BC) or both fentanyl (15 μg) and clonidine (30 μg) (Group BCF). The total amount of intrathecal mixture was constant (2.8 ml) in all the groups. Duration of sensory, motor block and effective analgesia, hemodynamic profile, postoperative pain score and analgesic requirements were recorded.

Results:

The duration of effective analgesia, mean time till two-segment regression, and duration of sensory and motor block were significantly longer in group BCF as compared to group BC (P ~ 0.002), and in group BC as compared to group BF (P ~ 0.01). The incidence of intraoperative pain and requirement of postoperative analgesics in the first 24 hours was significantly more in group BF as compared to the other groups (P ~ 0.01). There was no difference in the hemodynamic profile between the groups.

Conclusion:

Low-dose clonidine (30 μg) when added to a bupivacaine-fentanyl mixture increased the duration of effective analgesia and the duration of sensory and motor block in gynecological surgery. The incidence of intraoperative pain and requirement of postoperative analgesics was significantly less when clonidine was added to intrathecal bupivacaine with or without fentanyl.

Comparison of postoperative analgesic effect of intrathecal clonidine and fentanyl added to bupivacaine in patients undergoing cesarean section: a prospective randomized double-blind study

Objectives. To compare the analgesic efficacy of intrathecal clonidine and fentanyl added to bupivacaine after cesarean section. Methods. Ninety patients scheduled for cesarean section under spinal anesthesia were randomly allocated to one of the three following groups to receive bupivacaine 10 mg combined with 75 µg clonidine (group C), bupivacaine 10 mg combined with 0.5 mL fentanyl (group F), and bupivacaine 10 mg combined with 0.5 mL distilled water (group P), intrathecally. The time to first analgesic request, analgesic requirement in the first 24 hours after surgery, sensory and motor blockade onset time, duration of sensory and motor blockade, the incidence of hypotension, ephedrine requirements, bradycardia, and hypoxemia were recorded. Results. The duration of anesthesia in clonidine group (275.10 ± 96.09) was longer compared to the placebo (211.73 ± 74.80) and fentanyl (192.33 ± 30.36) groups. This difference between group C versus F (P = 0.006) and P groups (P < 0.001) was significant. Similarly, the mean time to first analgesic request was also longer in group C (519.44 ± 86.25) than in groups F (277.88 ± 94.25) and P (235.43 ± 22.35 min). This difference between group C versus F (P < 0.001) and P groups (P < 0.001) was significant. Conclusion. Intrathecal clonidine 75 µg with bupivacaine prolonged the time to first analgesic request compared to fentanyl; however, the total analgesic consumption within the first 24 h postoperative was similar in fentanyl and clonidine groups following cesarean section. This trial is registered with ACTRN12611000909921 and ClinicalTrials.gov NCT01425658.

Efficacy of premixed versus sequential administration of clonidine as an adjuvant to hyperbaric bupivacaine intrathecally in cesarean section

Background:

Density of the drugs injected intrathecally is an important factor that influences spread in the cerebrospinal fluid. Mixing adjuvants with local anesthetics (LA) alters their density and hence their spread compared to when given sequentially in seperate syringes.

Aims:

To evaluate the efficacy of intrathecal administration of hyperbaric bupivacaine (HB) and clonidine as a mixture and sequentially in terms of block characteristics, hemodynamics, neonatal outcome, and postoperative pain.

Setting and Design:

Prospective randomized single blind study at a tertiary center from 2010 to 2012.

Materials and Methods:

Ninety full-term parturient scheduled for elective cesarean sections were divided into three groups on the basis of technique of intrathecal drug administration. Group M received mixture of 75 μg clonidine and 10 mg HB 0.5%. Group A received 75 μg clonidine after administration of 10 mg HB 0.5% through separate syringe. Group B received 75 μg clonidine before HB 0.5% (10 mg) through separate syringe.

Statistical analysis used:

Observational descriptive statistics, analysis of variance with Bonferroni multiple comparison post hoc test, and Chi-square test.

Results:

Time to achieve complete sensory and motor block was less in group A and B in which drugs were given sequentially. Duration of analgesia lasted longer in group B (474.3 ± 20.79 min) and group A (472.50 ± 22.11 min) than in group M (337 ± 18.22 min) with clinically insignificant influence on hemodynamic parameters and sedation.

Conclusion:

Sequential technique reduces time to achieve complete sensory and motor block, delays block regression, and significantly prolongs the duration of analgesia. However, it did not matter much whether clonidine was administered before or after HB.

Prevention of hypotension and prolongation of postoperative analgesia in emergency cesarean sections: A randomized study with intrathecal clonidine

Background and Context:

Different adjuvants been tried out for neuraxial anesthesia in emergency caesarean section so that the dose of the local anesthetic can be reduced and hypotension thereby prevented.

Aims and Objectives:

The present study was carried out in patients presenting for emergency lower segment caesarean section (LSCS) to establish the dose of intrathecal clonidine that would allow reduction of the dose of local anesthetic (thereby reducing the incidence and magnitude of hypotension) while at the same time providing clinically relevant prolongation of spinal anesthesia without significant side effects.

Materials and Methods:

This randomized clinical study was carried out in our institution among 100 pregnant females who underwent emergency caesarean section. The participants were divided randomly into four groups: A, B, C, and D, each comprising 25 parturients. Subarachnoid block was performed using a 26G Quincke needle, with 12 mg of hyperbaric bupivacaine (LA) in group A, 9 mg of LA + 30 μg of clonidine in group B, LA + 37.5 μg of clonidine in group C, and LA + 45 μg of clonidine in group D. The solution was uniformly made up to 2.2 mL with normal saline in all the groups. Onset of analgesia at T₁₀ level, sensory and motor blockade levels, maternal heart rate and blood pressure, neonatal Apgar scores, postoperative block characteristics, and adverse events were looked for and recorded. Statistical analysis was carried out with SPSS^® version 10.0 for Windows^®, using the ANOVA test with post hoc significance, the Chi-square test, and the Mann-Whitney U test. P<.05 was considered significant and P<.0001 as highly significant.

Results:

One hundred patients were enrolled for this study. The four groups were comparable with regard to demographic data and neonatal Apgar scores. Onset and establishment of sensory and motor analgesia was significantly shorter in groups C and D, while hypotension (and the use of vasopressors) was significantly higher in groups A and D. Perioperative shivering, nausea, and vomiting were significantly higher in groups A and D, while incidence of dry mouth was significantly higher in group D.

Conclusions:

The addition of 45 μg, 37.5 μg, and 30 μg of clonidine to hyperbaric bupivacaine results in more prolonged complete and effective analgesia, allowing reduction of up to 18% of the total dose of hyperbaric bupivacaine. From the results of this study, 37.5 μg of clonidine seems to be the optimal dose.

Effects of imidazoline I₂ receptor ligands on morphine- and tramadol-induced antinociception in rats

Currently available analgesics cannot meet the increasing clinical needs and new analgesics with better therapeutic profiles are in great demand. The imidazoline I₂ receptor is an emerging drug target for analgesics. However, few studies have examined the effects of selective I₂ receptor ligands on the antinociceptive activity of opioids. This study examined the antinociceptive effects of the opioids morphine (0.1-10 mg/kg) and tramadol (3.2-56 mg/kg), the nonselective I₂ receptor ligand agmatine (10-100 mg/kg), and the selective I₂ receptor ligands 2-(2-benzofuranyl)-2-imidazoline hydrochloride (2-BFI; 1-10 mg/kg) and 2-(4, 5-dihydroimidazol-2-yl) quinoline hydrochloride (BU224; 1-10mg/kg), alone and in combination, in a warm water tail withdrawal procedure in rats. Morphine and tramadol but not agmatine, 2-BFI or BU224 increased tail withdrawal latency in a dose-related manner at 48°C water. Agmatine and 2-BFI but not BU224 dose-dependently enhanced the antinociceptive effects of morphine and tramadol, shifting the dose-effect curves of morphine and tramadol leftward. The enhancement of agmatine and 2-BFI on morphine and tramadol antinociception was prevented by BU224. These results, combined with the fact that BU224 and 2-BFI share similar behavioral effects under other conditions, suggest that BU224 has lower efficacy than 2-BFI at I₂ receptors, and that the enhancement of opioid antinociception by I₂ receptor ligands depends on their efficacies.

Dexmedetomidine and clonidine in epidural anaesthesia: A comparative evaluation

Efforts to find a better adjuvant in regional anaesthesia are underway since long. Aims and objectives are to compare the efficacy and clinical profile of two α-2 adrenergic agonists, dexmedetomidine and clonidine, in epidural anaesthesia with special emphasis on their sedative properties and an ability to provide smooth intra-operative and post-operative analgesia. A prospective randomized study was carried out which included 50 adult female patients between the ages of 44 and 65 years of (American Society of Anaesthesiologists) ASAI/II grade who underwent vaginal hysterectomies. The patients were randomly allocated into two groups; ropivacaine + dexmedetomidine (RD) and ropivacaine + clonidine (RC), comprising of 25 patients each. Group RD was administered 17 ml of 0.75% epidural ropivacaine and 1.5 μg/kg of dexmedetomidine, while group RC received admixture of 17 ml of 0.75% ropivacaine and 2 μg/kg of clonidine. Onset of analgesia, sensory and motor block levels, sedation, duration of analgesia and side effects were observed. The data obtained was subjected to statistical computation with analysis of variance and chi-square test using statistical package for social science (SPSS) version 10.0 for windows and value of P < 0.05 was considered significant and P < 0.0001 as highly significant. The demographic profile, initial and post-operative block characteristics and cardio-respiratory parameters were comparable and statistically non-significant in both the groups. However, sedation scores with dexmedetomidine were better than clonidine and turned out to be statistically significant (P < 0.05). The side effect profile was also comparable with a little higher incidence of nausea and dry mouth in both the groups which was again a non-significant entity (P > 0.05). Dexmedetomidine is a better neuraxial adjuvant compared to clonidine for providing early onset of sensory analgesia, adequate sedation and a prolonged post-operative analgesia.

Comparison of epidural ropivacaine and ropivacaine clonidine combination for elective cesarean sections

Background and Aim:

Neuraxial adjuvants augment the action of local anesthetics. The aim is to determine the qualitative and quantitative aspects of epidural block of ropivacaine 0.75% versus ropivacaine 0.75% with clonidine for elective cesarean section.

Settings and Design:

A randomized double-blind study was conducted among 51 healthy parturients, scheduled for elective cesarean section, at Gian Sagar Medical College and Hospital, Banur, Punjab, India.

Materials and Methods:

Epidural block was administered with 20 ml of ropivacaine 0.75% (group R) and ropivacaine 0.75% and clonidine 75 µg (group RC) and anesthetic level was achieved minimum until T6–T7 dermatome. Onset time of analgesia, sensory and motor block levels, maternal heart rate and blood pressure, neonatal Apgar scores, postoperative analgesic dose and adverse events were recorded.

Results:

Fifty one patients were enrolled in this study and were subjected to statistical analysis. Groups were comparable with regard to demographic data, neonatal Apgar scores and incidences of side effects except for the higher incidence of dry mouth in patients of RC group. Onset of analgesia was much shorter in RC group along with prolonged duration of analgesia. The incidence of bradycardia and hypotension was more in RC group as compared to R group which was statistically significant. The dose requirement for postoperative pain relief was significantly lesser in RC group.

Conclusions:

The addition of 75 µg clonidine to isobaric epidural ropivacaine results in longer, complete and effective analgesia with similar block properties and helped to reduce the effective dose of ropivacaine when compared with plain ropivacaine for cesarean delivery.

Progress in analgesia for labor: focus on neuraxial blocks

Neuraxial analgesia is widely accepted as the most effective and the least depressant method of providing pain relief in labor. Over the last several decades neuraxial labor analgesia techniques and medications have progressed to the point now where they provide high quality pain relief with minimal side effects to both the mother and the fetus while maximizing the maternal autonomy possible for the parturient receiving neuraxial analgesia. The introduction of the combined spinal epidural technique for labor has allowed for the rapid onset of analgesia with minimal motor blockade, therefore allowing the comfortable parturient to ambulate. Patient-controlled epidural analgesia techniques have evolved to allow for more flexible analgesia that is tailored to the individual needs of the parturient and effective throughout the different phases of labor. Computer integrated systems have been studied to provide seamless analgesia from induction of neuraxial block to delivery. New adjuvant drugs that improve the effectiveness of neuraxial labor analgesia while decreasing the side effects that may occur due to high dose of a single drug are likely to be added to future labor analgesia practice. Bupivacaine still remains a popular choice of local anesthetic for labor analgesia. New local anesthetics with less cardiotoxicity have been introduced, but their cost effectiveness in the current labor analgesia practice has been questioned.

[30 microg intrathecal clonidine prolongs labour analgesia, but increases the incidence of hypotension and abnormal foetal heart rate patterns]

OBJECTIVE

To assess the efficacy of spinal clonidine combined with bupivacaine and sufentanil and its effects on maternal and foetal outcome.

STUDY DESIGN

Prospective double-blind randomized study.

PATIENTS AND METHODS

One hundred and five patients requesting labour analgesia had combined spinal epidural analgesia with intrathecal bupivacaine 2.5 mg and were randomly assigned to receive in addition either sufentanil 5 microg (S5), sufentanil 5 microg and clonidine 30 microg (C30), or sufentanil 10 microg (S10). Onset time, duration of analgesia, visual analogue scores, blood pressure, ephedrine requirements, heart rate, nausea, pruritus, sedation, motor block, foetal heart rate abnormalities, mode of delivery and Apgar scores were recorded.

RESULTS

Mean duration of spinal analgesia was significantly longer in patients receiving spinal clonidine compared to patients in S5 group (144+/-61 min versus 95+/-37 min). The onset time of analgesia was significantly shorter in S10 group (3+/-1 min) versus C30 group (4+/-1 min) and S5 group (4+/-1 min) (P=0.002). Hypotension was significantly more frequent in C30 group (29 versus 3% and 3% in S5 and S10 groups) (p=0,001). Foetal heart rate abnormalities and sedation were also significantly more frequent in C30 group. Mode of delivery (spontaneous, instrumental or caesarean delivery) and Apgar scores were unaffected by clonidine treatment.

CONCLUSION

Intrathecal clonidine 30 mug prolongs analgesia. However, it increases the incidence of hypotension, and abnormal foetal heart rate patterns. Thus, this study confirms that the use of 30 mug intrathecal clonidine for labour analgesia is not recommended.

Alpha 2 agonists in regional anesthesia and analgesia

Clonidine is a partial alpha 2 adrenergic agonist that has a variety of different actions including antihypertensive effects as well as the ability to potentiate the effects of local anesthetics. It can provide pain relief by an opioid-independent mechanism. It has been shown to result in the prolongation of the sensory blockade and a reduction in the amount or concentration of local anesthetic required to produce perioperative analgesia. Different routes for the administration of regional anesthesia, including intravenous, intrathecal and epidural ones, as well as the addition of clonidine for peripheral neural blockade, have been described. It has been also used for intra-articular administration. The latest articles describing the use of clonidine in regional anesthesia are discussed. Most authors agree that the use of clonidine for regional neural blockade in combination with a local anesthetic results in increased duration of sensory blockade with no difference in onset time. The addition of clonidine to the local anesthetic opioid mixtures seems to produce analgesia of longer duration, more rapid onset and higher quality. The higher doses of clonidine were associated with a more cephalad spread of the spinal blockade and increased sedation and hypertension. When clonidine is added to a fentanyl-bupivacaine mixture for epidural labor analgesia, it seems to provide satisfactory analgesia of a longer duration than that produced by the fentanyl-bupivacaine combination alone. Similar results were found when epidural analgesia using levobupivacaine with clonidine was used in patients undergoing total hip arthroplasty. Less clear results were seen when clonidine was used for caudal anesthesia in a pediatric patient population. The addition of clonidine to intravenous regional anesthesia resulted in prolongation of the tourniquet time and improvement of postoperative analgesia. However, the latter was found to be short-lived. In another study, the effects of clonidine used for intra-articular administration in combination with morphine were investigated. These authors found a significantly higher rate of satisfaction in the group of patients receiving clonidine plus morphine. Although several recent studies have shown certain benefits from the use of clonidine for regional anesthesia, further investigations are necessary to clarify its role.

The use of neuraxial adjuvant drugs (neostigmine, clonidine) in obstetrics

PURPOSE OF REVIEW

Neuraxial adjuvant drugs are used to improve analgesia and to decrease complications associated with a high dose of a single drug. Opioids are used in routinely, but alpha2-agonists, such as clonidine or cholinesterase inhibitors (neostigmine), have also been used for labour analgesia or to relieve pain following caesarean section. Both drugs possess a common mechanism of action that can be beneficial.

RECENT FINDINGS

Small doses of intrathecal clonidine (30 microg), combined with local anaesthetics and opioids, prolong labour analgesia. Hypotension can occur and must be promptly treated by ephedrine to avoid fetal side effects. Epidural clonidine (60 to 75 microg) produces prolonged analgesia from local anaesthetics and opioids and allows a ropivacaine sparing effect. Intrathecal neostigmine has analgesic properties, but its gastro-intestinal side effects contraindicate its clinical use. Epidural neostigmine, combined with sufentanil or clonidine, initiates labour analgesia (minimum 6 to 7 microg/kg; 500 microg) without side effects, however, and allows a 'mobile epidural'. Epidural and spinal clonidine can be used to improve postcaesarean section analgesia. Epidural neostigmine at the doses studied produces modest analgesia following caesarean section.

SUMMARY

Co-administration of neuraxial drugs may enhance analgesia and reduce the side effects of each drug. Clonidine and neostigmine may be used in obstetrics, under some conditions.

Improved analgesia with clonidine when added to local anesthetic during combined spinal-epidural anesthesia for hip arthroplasty: a double-blind, randomized and placebo-controlled study

BACKGROUND

The perioperative effects of intrathecal and epidural clonidine combined with local anesthetic were evaluated in 60 patients undergoing hip arthroplasty.

METHODS

This was a double-blinded study and the patients were randomized into three groups, with 20 patients in each group. All patients received spinal anesthesia with 17.5 mg of plain bupivacaine with 15 microg of clonidine (Group BC-RC) or without clonidine (Groups B-R and B-RC). Postoperatively, epidural infusion was administered in the following way: Group B-R-ropivacaine 4 mg h(-1); Groups B-RC and BC-RC: ropivacaine 4 mg h(-1) and clonidine 40 microg h(-1). Sensory block was assessed with light touch, pinprick, transcutaneous electrical stimulation at T12 and L2 dermatomes, and perception of thermal stimuli.

RESULTS

The maximal upper level of sensory block measured by pin-prick (T6-T7) did not differ between the groups while the partial sensory block for cold and warmth were increased two dermatomes above pin-prick level in the group with intrathecal clonidine compared to the other two groups (P < 0.05). Duration of anesthesia, analgesia and motor block were longer in Group BC-RC compared to Groups B-R and B-RC (P < 0.02). Postoperatively, both VAS score on movement and PCA-morphine consumption were higher in Group B-R than in Groups B-RC and BC-RC (P < 0.01). The arterial pressure and heart rate in Groups B-RC and BC-RC were significantly lower than in Group B-R at 10-24 and 15-24 h, respectively, after spinal injection.

CONCLUSION

Low-dose intrathecal clonidine provided a better quality of anesthesia and longer-lasting analgesia. Epidural clonidine-ropivacaine infusion resulted in improved postoperative analgesia but was associated with a moderate decrease in blood pressure.

The in vitro effects of clonidine and dexmedetomidine on human myometrium

BACKGROUND

alpha(2)-adrenergic agonists have been used extensively in the field of anaesthesia. Their direct effect on the human myometrium was investigated in this in vitro study, as this may have clinical repercussions in obstetric anaesthesia.

METHOD

Strips of pregnant human myometrium obtained from six individuals at elective caesarean section were mounted on the Mulvany myograph in Krebs solution to which increasing concentrations of clonidine and dexmedetomidine (1x10(-11) to 1x10(-6) g/mL) were added.

RESULTS

Dexmedetomidine increased uterine contractility at simulated clinical plasma concentrations (1x10(-9) g/mL). These effects were seen with clonidine only at much higher tissue bath concentrations (1x10(-7) g/mL).

CONCLUSION

The effect of dexmedetomidine on human myometrium has profound implications in obstetric anaesthesia and needs further clinical investigation.

Intrathecal clonidine prolongs labour analgesia but worsens fetal outcome: a pilot study

PURPOSE

Intrathecal clonidine prolongs total duration of spinal bupivacaine analgesia. However, there are contradictory reports about its effect on maternal blood pressure and only limited data are available on fetal and neonatal outcome. In this study, we evaluated the efficacy of spinal clonidine combined with ropivacaine and sufentanil and its effects on maternal and fetal outcome.

METHODS

Fifty patients requesting combined spinal epidural analgesia for labour pain relief were randomly assigned to receive intrathecal ropivacaine 3 mg, sufentanil 1.5 microg with or without clonidine 30 microg. Onset time and duration of analgesia, visual analogue scores for pain, blood pressure, ephedrine requirements, heart rate, incidence of nausea, pruritus and motor blockade, umbilical artery pH, fetal heart rate abnormalities and Apgar scores were noted and analyzed.

RESULTS

Patients receiving spinal clonidine had significantly longer lasting analgesia compared to patients treated without clonidine (122 +/- 56 min vs 90 +/- 36 min, P < 0.05). Clonidine-treated patients experienced a more pronounced decrease in mean arterial pressure as compared to patients treated without clonidine (25 +/- 10% vs 15 +/- 12%, P < 0.05). The groups also differed in ephedrine requirement (4.91 mg vs 0.75 mg, P < 0.05), number of new onset fetal heart rate abnormalities (28% vs 0%, P < 0.05) and umbilical artery pH (7.219 +/- 0.096 vs 7.289 +/- 0.085, P < 0.05).

CONCLUSION

Intrathecal clonidine prolongs spinal analgesia with ropivacaine and sufentanil at the expense of maternal hypotension, worse fetal well being and worse neonatal umbilical artery pH. We do not recommend routine administration of spinal clonidine 30 microg to sufentanil and ropivacaine for labour pain relief.

Small-Dose Intrathecal Clonidine and Isobaric Bupivacaine for Orthopedic Surgery: A Dose-Response Study

We examined the dose-response relationship of intrathecal clonidine at small doses (<or=150 microg) with respect to prolonging bupivacaine spinal anesthesia. We aimed for establishing doses of intrathecal clonidine that would produce clinically relevant prolongation of spinal anesthesia and pain relief without significant side effects. Eighty orthopedic patients were randomly assigned to intrathecally receive isobaric 0.5% bupivacaine, 18 mg, plus saline (Group 1), clonidine 37.5 microg (Group 2), clonidine 75 microg (Group 3), and clonidine 150 microg (Group 4). Duration of the sensory block (regression below level L1) was increased in patients receiving intrathecal clonidine: 288 +/- 62 min (Group 1, control), 311 +/- 101 min in Group 2 (+8%), 325 +/- 69 min in Group 3 (+13%), and 337 +/- 78 min in Group 4 (+17%) (estimated parameter for dose 0.23 [95% confidence interval -0.05-0.50]). Duration of pain relief from intrathecal clonidine administration until the first request for supplemental analgesia was significantly prolonged: 295 +/- 80 min (Group 1, control), 343 +/- 75 min in Group 2 (+16%), 381 +/- 117 min in Group 3 (+29%), and 445 +/- 136 min in Group 4 (+51%) (estimated parameter for dose 1.02 [95% confidence interval 0.59-1.45]). Relative hemodynamic stability was maintained and there were no between-group differences in the sedation score. We conclude that small doses of intrathecal clonidine (<or=150 microg) significantly prolong the anesthetic and analgesic effects of bupivacaine in a dose-dependent manner and that 150 microg of clonidine seems to be the preferred dose, in terms of effect versus unwarranted side effects, when prolongation of spinal anesthesia is desired.

Intrathecal opioids for combined spinal-epidural analgesia during labour

In <25 years, intrathecal administration of opioids (i.e. spinal analgesia) has evolved from an experimental model into an important therapy for obstetric analgesia and anaesthesia. A small dose of opioid delivered into the CSF provides almost immediate relief from labour pain with minimal risks to the mother and fetus. Careful attention, and prompt treatment when needed, can ameliorate the adverse effects of fetal bradycardia, respiratory depression and pruritus. The major limitation of intrathecal opioids for labour analgesia is the short duration of effect: 90-180 minutes under ideal circumstances. To address this problem, and to increase flexibility for anaesthesia as well as analgesia, the combined spinal-epidural (CSE) technique was developed. The CSE technique involves injection of drugs into the CSF and placement of an epidural catheter. An intrathecally administered opioid provides a rapid onset of labour analgesia without motor block or significant haemodynamic perturbation. The epidural catheter allows ongoing administration of medications to maintain labour analgesia and provides a means of delivering anaesthesia for operative delivery. This review will focus on intrathecally administered opioids as used as part of CSE analgesia. Considerable research has focused on the optimum dose of opioids when delivered intrathecally, with or without adjuncts, in the CSE technique. Fentanyl and sufentanil, two of the lipophilic synthetic opioids, have emerged as the most useful. Bupivacaine, a long-acting local anaesthetic, is often added to prolong the duration of analgesia, although this tends to increase the likelihood of motor blockade of the lower extremities. Comparisons of the CSE technique with standard epidural practices have shown that both are effective means of providing analgesia during labour. Controversy revolves around the incidence of fetal bradycardia following CSE and whether this phenomenon increases the rate of operative deliveries. The rapid onset of analgesia with intrathecally administered opioids must be balanced against the added risks of dural puncture and considered in the context of the whole duration of labour. Ultimately, the decision to choose a CSE technique depends on the experience of the anaesthesia provider and the local availability of drugs, equipment and monitoring capabilities.

Hyperbaric bupivacaine 2.5 mg prolongs analgesia compared with plain bupivacaine when added to intrathecal fentanyl 25 microg in advanced labor

We investigated the effect of sequential administration of intrathecal (IT) hyperbaric bupivacaine (after the initial administration of IT hypobaric fentanyl) on the duration of spinal analgesia. Thirty-seven nulliparous parturients with a cervical dilation >/= 5 cm were randomized to receive either IT fentanyl 25 micro g and plain bupivacaine 2.5 mg (group P; n = 19) or IT fentanyl 25 micro g and hyperbaric (with 8% glucose) bupivacaine 2.5 mg (group H; n = 18). The two components of the IT injectate were administered sequentially (fentanyl 25 micro g diluted in 2 mL of normal saline, immediately followed by 0.5 mL of 0.5% bupivacaine). Patients were then positioned with their torso elevated at 30 degrees for 30 min. Pain scores using 0-100 visual analog scales were collected before combined spinal/epidural analgesia and at 5, 15, and 30 min after the block. Patients in Group H had a longer median duration of analgesia (122 min; range, 80-210 min) than Group P (95 min; range, 75-125 min) (P < 0.01). Group H also had a more limited dermatomal spread (median highest sensory level of T8 versus T4 in group P; P < 0.05). The side-effect profile was similar. Under these circumstances, hyperbaric bupivacaine conferred an increased duration of IT analgesia compared with plain bupivacaine.

Effects of intrathecally administered dexmedetomidine, MPV-2426 and tizanidine on EMG in rats

BACKGROUND

When administered intrathecally, alpha-2 adrenergic agonists produce spinally mediated antinociception, but also rapidly redistribute to supraspinal sites. This investigation the compared EMG effects of intrathecally administered dexmedetomidine, MPV-2426 (fadolmidine), and tizanidine in Sprague-Dawley rats, which has not been previously described.

METHODS

We studied electromyographic (EMG) responses of the head and gastrocnemius muscles, antinociception using the tail-flick test, and sedation by using observer assessment. Saline, dexmedetomidine (0.5 microg, 2.5 microg and 12.5 microg), MPV-2426 (2 microg, 10 microg and 50 microg) and tizanidine (2 microg, 10 microg and 50 microg) were administered intrathecally.

RESULTS

Tizanidine 50 microg, MPV-2426 10 microg and 50 microg, and dexmedetomidine 2.5 microg and 12.5 microg, decreased EMG activity (P < 0.005). Dexmedetomidine 12.5 microg, MPV-2426 50 microg, and tizanidine 10 microg and 50 microg increased tail-flick latencies (P < 0.01). Dexmedetomidine alone significantly increased the magnitude of observer-assessed sedation (P < 0.0001).

CONCLUSION

We conclude that in rats, intrathecally administered dexmedetomidine, MPV-2426 and tizanidine have dose-dependent effects on EMG. At antinociceptive doses, the EMG effects of these three alpha-2 adrenergic agonists differ (dexmedetomidine > MPV-2426 > tizanidine).

A randomized, double-blinded trial of subarachnoid bupivacaine and fentanyl, with or without clonidine, for combined spinal/epidural analgesia during labor

Subarachnoid clonidine may increase the duration of spinal opioid and local anesthetic analgesia during labor, but it may also increase hypotension and sedation, and the therapeutic range is unclear. We studied 110 term parturients of mixed parity having combined spinal/epidural analgesia during labor in this randomized, double-blinded trial. All received subarachnoid fentanyl 20 micro g and bupivacaine 2.5 mg, plus either saline or clonidine (15, 30, or 45 micro g). Of 101 per-protocol parturients (n = 25, 24, 26, and 26 in Groups C0, C15, C30, and C45, respectively), 22 delivered before the cessation of spinal analgesia. Group demographics and pain scores from Time 0 to 120 min were similar. There was no significant difference among groups in the duration of spinal analgesia (P = 0.09) or in the duration of clonidine groups combined compared with control (median, 120 min [interquartile range, 96-139 min] versus 98 min [80-120 min]; P = 0.07). Systolic blood pressure was significantly lower in all clonidine groups between 40 and 90 min (P = 0.001). Hypotension (P = 0.05) and the requirement for ephedrine (P = 0.02) were dose dependent, but groups had a similar incidence of hypotension. The addition of clonidine 15-45 micro g to subarachnoid fentanyl and bupivacaine reduced blood pressure and did not significantly increase the duration of spinal analgesia.

IMPLICATIONS

The addition of 15-45 micro g of clonidine to subarachnoid fentanyl plus bupivacaine did not significantly increase the duration of spinal analgesia but did decrease maternal blood pressure. The results of this study do not support the use of subarachnoid clonidine to prolong the action of spinal labor analgesia when fentanyl plus bupivacaine are administered.

Epinephrine and clonidine do not improve intrathecal sufentanil analgesia after total hip replacement

BACKGROUND

We compared analgesia after intrathecal sufentanil alone, sufentanil with epinephrine 200 microg and sufentanil with clonidine 30 microg in patients after total hip replacement, the endpoints being onset and duration of action.

METHODS

We performed a randomized double-blind study of 45 patients for elective total hip arthroplasty using continuous spinal anaesthesia. As soon as a pain score higher than 3 on a 10 cm visual analogue scale was reported, sufentanil 7.5 microg alone, sufentanil 7.5 microg + epinephrine 200 microg or sufentanil 7.5 microg + clonidine 30 micro g in 2 ml normal saline was given intrathecally. Pain scores, rescue analgesia (diclofenac and morphine) and adverse effects (respiratory depression, postoperative nausea and vomiting, itching) were observed for 24 h after surgery.

RESULTS

Time to a pain score of <3 [6 (SD 1) vs 6 (1) vs 5 (1) min], time to the lowest pain score [7 (2) vs 8 (2) vs 8 (2) min] and time to the first dose of systemic analgesic for a pain score >3 [281 (36) vs 288 (23) vs 305 (30) min] were similar in all three groups. Adverse effects and analgesic requirements during the first 24 h were also similar.

CONCLUSION

After total hip replacement, all three analgesic regimens gave good analgesia with comparable onset and duration of action, and minor adverse effects.

Alpha2 receptors and agonists in pain management

Alpha(2) agonists have been in clinical use for decades, primarily in the treatment of hypertension. In recent years, alpha(2) agonists have found wider application, particularly in the fields of anesthesia and pain management. It has been noted that these agents can enhance analgesia provided by traditional analgesics, such as opiates, and may result in opiate-sparing effects. This has important implications for the management of acute postoperative pain and chronic pain states, including disorders involving spasticity or myofascial pain, neuropathic pain, and chronic daily headaches. The clinical utility of these agents is ever expanding, as they are gaining broader use in neuraxial analgesia, and new applications are continuously under investigation. The alpha(2) agonists that are currently employed in anesthesia and pain management include clonidine, tizanidine, and dexmedetomidine. Moxonidine and radolmidine, which are not currently in clinical use in humans, may offer favorable side-effect profiles when compared with traditional alpha(2) agonists, and may thereby allow for more widespread pain management applications.