Dose-response effects of spinal neostigmine added to bupivacaine spinal anesthesia in volunteers

Use of Intrathecal Neostigmine as an Adjunct to Other Spinal Medications in Perioperative and Peripartum Analgesia: A Meta-analysis

Intrathecal neostigmine has been used as an adjunct to intrathecal local anaesthetic or opioid to prolong regional analgesia and improve haemodynamic stability, with variable results. This meta-analysis aims to evaluate the effectiveness and side-effects of intrathecal neostigmine in the perioperative and peripartum settings. The literature search was based on Cochrane Controlled Trials Register, EMBASE and MEDLINE (from 1966 to 14 November 2003) databases. Volunteer and animal studies were excluded. We identified 26 studies and 19 were considered suitable for detailed data extraction. Intrathecal neostigmine increased the incidence of nausea and vomiting (OR 5.0, 95% CI: 3.4 to 7.3; P<0.00001), bradycardia requiring intravenous atropine (OR 2.7, 95% CI: 1.4 to 5.4; P=0.005), and anxiety, agitation, or restlessness (OR 10.3, 95% CI: 3.7 to 28.9; P=0.00001). It improved the overall 24 hour VAS score (–1.4 VAS pain score, 95% CI: -1.7 to -1.2, P<0.00001), delayed the time of first request for rescue analgesia (168 min, 95% CI: 125 to 211; P<0.00001), and reduced the total number of rescue injections of nonsteroidal anti-inflammatory drug within the first 24 hours (-0.8, 95% CI: -1.1 to -0.4; P=0.00001). It did not affect the duration of motor blockade (3.5 min, 95% CI: -1.5 to 8.6; P=0.17) or the total amount of ephedrine required (-0.4 mg, 95% CI: -1.5 to 0.7; P=0.5). Adding intrathecal neostigmine to other spinal medications improves perioperative and peripartum analgesia marginally when compared with placebo. It is associated with significant side-effects and the disadvantages outweigh the minor improvement in analgesia achieved.

A Comparison of Intrathecal Dexmedetomidine and Neostigmine as Adjuvant to Ropivacaine for Lower Limb Surgeries: A Double-blind Randomized Controlled Study

Objective:

The primary objective of this study was to compare the analgesic effects of intrathecal ropivacaine with or without neostigmine or dexmedetomidine in lower limb surgeries. Secondary objectives were to study the characteristics of block, duration of analgesia, postoperative analgesic requirement, and associated side effects.

Materials and Methods:

Seventy-five patients posted for elective orthopedic lower limb surgeries under spinal anesthesia were randomly divided into three equal groups to receive intrathecal ropivacaine 0.5% alone (Group R), with adjuvant 5 μg dexmedetomidine (Group R + D) or 50 μg neostigmine (Group R + N). Time to achieve T10 sensory block, time to 2-segment regression, duration of regression to L4, maximum modified Bromage score and duration of analgesia were noted. The incidences of adverse events such as nausea, vomiting, hypotension, bradycardia, desaturation, shivering, and itching were also noted. Statistical analysis was performed using two sample t-test for normally distributed variables and Pearson's Chi-squared test for categorical data. The level of significance was set as P < 0.05.

Results:

Quality of motor and sensory blockage was significantly better in both Group R + D and Group R + N than Group R. Mean time to achieve T10 sensory block was lowest, time taken in regression of block by 2-segments and duration of regression to L4 was longest in Group R + D and was significant when compared to other groups. Adverse effects such as nausea and vomiting were highest in Group R + N and was statistically significant as compared to other groups.

Conclusions:

Dexmedetomidine is a better intrathecal adjuvant emerged as compared to neostigmine due to faster onset of anesthesia, better intra- and post-operative analgesia and prolonged duration of motor and sensory blockade without significant increase in adverse effects.

Effect of adding clonidine to intrathecal bupivacaine on the quality of subarachnoid block: A prospective randomized double-blind study

Context:

The purpose of adding an adjuvant to local anesthetic in a central neuraxial blockade is to augment the desirable pharmacological actions of the agent and/or to minimize its undesirable pharmacological effects. Clonidine is an alfa-2 receptor agonist which has gained popularity in recent times as an adjuvant in spinal anesthesia.

Aims:

To evaluate the influence of clonidine on the hemodynamic stability and the duration of anesthesia when added to intrathecal hyperbaric bupivacaine.

Settings and Design:

Prospective randomized double blind study.

Subjects and Methods:

Fifty patients scheduled for spinal anesthesia were randomized into two Groups A and B with 25 in each. Group A patients received 3 ml 0.5% heavy bupivacaine + 30 μg (0.2 ml) clonidine and Group B patients received 3 ml 0.5% heavy bupivacaine + 0.2 ml normal saline in the subarachnoid space. The blood pressure and heart rate were closely monitored. The time for attaining peak sensory block, time for two segment regression, decrease in the heart rate, total requirement of mephentermine to counter the hypotension, and the number of patients requiring mephentermine in each group was tabulated and analyzed.

Statistical Analysis Used:

Descriptive and inferential statistical methods were used to analyse the data. The power of the study was calculated using online power calculator for two independent sample study.

Results:

The time for attaining peak sensory block was similar in both the groups. The time for two segment regression in Group A was 62.6 min and in Group B was 38.08 min. Twelve percent of patients in Group A and 52% of patients in Group B required mephentermine with the mean consumption being 0.72 mg in Group A and 5.65 mg in Group B.

Conclusions:

Addition of low-dose clonidine to intrathecal bupivacaine not only prolonged the duration of spinal anesthesia but also provided a stable intraoperative hemodynamic profile.

Comparative evaluation of different doses of intrathecal neostigmine as an adjuvant to bupivacaine for postoperative analgesia

Objective:

To study the efficacy and safety of intrathecal neostigmine at dose of 50 μg and 150 μg as an adjuvant to bupivacaine for postoperative analgesia under spinal anesthesia.

Materials and Methods:

75 patients of either sex, belonging to American Society of Anesthesiologists (ASA) physical status I and II in the age group of 30-65 years scheduled to undergo lower abdominal and lower limb surgeries were allocated randomly into 3 groups of 25 each. Spinal anesthesia was administered in Group I (control group) with 12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine, in Group II (50 μg group) with 12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine and 50 μg (0.1 ml) of neostigmine methylsulphate and in Group III (150 μg group) with 12.5 mg (2.5 ml) of 0.5% hyperbaric bupivacaine and 150 μg (0.3 ml) of neostigmine methylsulphate. Hemodynamic parameters, onset and level of sensory block were recorded. Postoperative analgesic assessment was made in terms of total Visual Analogue Scale-Pain (VAS-P) scores in 24 hrs, duration of analgesia (time to requirement of first analgesic) and total number of rescue analgesic (diclofenac sodium 75 mg intramuscularly) consumption in 24 hours. Side effects were recorded.

Results:

The total VAS-P score in group I was 23.12 ± 3.21, which was higher than the VAS-P score in group II (18.4 ± 2.92) and group III (16.24 ± 1.85). The total duration of analgesia was significantly prolonged in neostigmine groups (224.40 ± 23.28 min in group I, 367.60 ± 42.15 min in group II and 625.60 ± 87.70 min in group III). In group I, the patients required 2.48 ± 0.51 number of analgesics in 24 hours, which was much higher than required in group II (1.92 ± 0.64) and group III (1.32 ± 0.47). The incidence of nausea and vomiting was more with 150 μg neostigmine group compared to 50 μg neostigmine.

Conclusions:

The administration of intrathecal neostigmine in dose of 50 μg as an adjuvant to bupivacaine produces hemodynamically stable analgesia with minimal side effects.

Optimal single-dose epidural neostigmine for postoperative analgesia after partial hepatectomy

Objective:

Neostigmine can produce analgesia by acting on the spinal cord. This study was to determine the optimal single-dose of epidural neostigmine for postoperative analgesia after partial hepatectomy.

Patients and Methods:

Twenty-six patients undergoing elective partial hepatectomy under general anesthesia combined with epidural block were studied. The dose of epidural neostigmine was determined using Dixon's up-and-down method, starting from neostigmine 100 μg with an interval of 25 μg. Thirty minutes after skin incision, a predetermined dose of neostigmine was injected via the epidural catheter. Each patient received 0.125% bupivacaine and fentanyl 2 μg/ml for patient controlled epidural analgesia (PCEA) after the operation. Assessment of analgesia quality was performed at 8 h and 24 h after the operation.

Results:

The ED₅₀ of epidural neostigmine in combination with PCEA for satisfactory analgesia was 226.78 ± 33.20 μg. Probit analysis showed that the ED₅₀ and ED₉₅ of epidural neostigmine were 228.63 μg (95% CI = 197.95–299.77 μg) and 300.12 μg (95% CI = 259.44–741.65 μg), respectively.

Conclusion:

The ED₅₀ and ED₉₅ of epidural neostigmine in combination with PCEA for satisfactory analgesia after partial hepatectomy were 228.63 μg (95% CI = 197.95–299.77 μg) and 300.12 μg (95% CI = 259.44–741.65 μg).

Efficacy of spinal additives neostigmine and magnesium sulfate on characteristics of subarachnoid block, hemodynamic stability and postoperative pain relief: A randomized clinical trial

Background:

Intrathecal neostigmine and magnesium sulfate (MgSO₄) produce substantial antinociception, potentiate analgesia of bupivacaine without neurotoxicity.

Aims:

The aim was to investigate the effect of neostigmine and MgSO₄ on characteristics of spinal anesthesia (SA), hemodynamic stability and postoperative analgesia when added to 0.5% hyperbaric bupivacaine for SA.

Subjects and Methods:

In this prospective, randomized, double-blind study 75 American Society of Anesthesiologist status I and II adult females posted for major gynecological surgery were assigned to one of the three groups (n = 25). Group N received Neostigmine 25 μg, Group M received MgSO₄ 50 mg, Group C received 0.5 ml saline as an adjuvant to 17.5 mg hyperbaric bupivacaine. Onset, duration of block, heart rate, mean arterial pressure, postoperative analgesia, analgesic requirement, and adverse effects were recorded. Data expressed as mean (standard deviation) or number (%). P <0.05 were statistically significant.

Results:

The three groups were comparable in characteristics of SA. The mean duration of analgesia was significantly longer in Group N (5.1 h) followed by Group M (4.2 h) and Group C (3.8 h) (P = 0.0134). Analgesic requirement was significantly less in Group N followed by Group M and Group C (P = 0.00232). The pain score was significantly less in Group M (P < 0.05). The incidence of hypotension and vasopressor requirement was lowest (48%) in Group N than in Group M (64%) and Group C 84% (P = 0.0276). The incidence of bradycardia and atropine requirement was the lowest in Group M (P = 0.0354). Sedation was observed in 56% patients in Group M compared to 20% in Group N and 8% in Group C (P = 0.0004).

Conclusion:

Intrathecal Neostigmine and MgSo₄ does not affect characteristics of SA. Postoperative analgesia of neostigmine was better than MgSO₄. Neostigmine provides some protection against hypotension of SA whereas MgSO₄ protects against bradycardia.

The evolution of spinal/epidural neostigmine in clinical application: Thoughts after two decades

Since the first clinical application of analgesia following spinal anticholinesterase by 1940's, several clinical double-blind studies have been conducted to date, where intrathecal doses of neostigmine in humans ranged from 750 to 1 μg, due to side-effects. Conversely, epidural neostigmine has been evaluated in proportionally higher doses and represents an alternative, but still deserves more investigation concerning both acute and chronic pain, as it seems devoid of important side-effects.

A comparative study between intrathecal clonidine and neostigmine with intrathecal bupivacaine for lower abdominal surgeries

Background and Aims:

Spinal anaesthesia requires a small volume of drug to produce profound reproducible sensory analgesia and motor blockade, but has limited duration of action. A properly chosen adjuvant to local anaesthetic agent produces the best way to achieve a better quality regional block. Hence, a study was conducted to compare the effect of intrathecal clonidine 75 μg or neostigmine 50 μg added to intrathecal hyperbaric bupivacaine, with regards to sensory characteristics, motor characteristics, haemodynamic stability and side effects.

Methods:

This was a prospective randomized experimental study in 50 patients posted for lower abdominal surgery belonging to ASA I and II status and aged between18 and 60 years. One group received intrathecal clonidine 75 μg and 2.5 ml (12.5 mg) of intrathecal 0.5% hyperbaric bupivacaine (group BC) and second group received neostigmine 50 μg with 2.5 ml (12.5mg) of intrathecal 0.5% hyperbaric bupivacaine (group BN) and they were compared with regards to sensory characteristics, motor characteristics, haemodynamic stability and side effects.

Results:

Addition of 50 μg neostigmine significantly enhanced the onset of sensory block (BN - 90 ± 15 secs, BC-160 ± 20 secs, P value as <0.05) and motor block (BN-110 ± 15 secs, BC-210 ± 20 secs, P value as <0.05) compared to clonidine. Haemodynamics were well maintained in the neostigmine group. Group BC had prolonged analgesia (362 ± 36 mins) compared to BN group (300 ± 25 mins)(P < 0.05) with no serious adverse effects noted perioperatively in either groups.

Conclusion:

Intrathecal clonidine with hyperbaric bupivacaine produces prolonged postoperative analgesia and intrathecal neostigmine with bupivacaine produces a good sensory and motor for the surgical procedure.

A study to compare the analgesic efficacy of intrathecal bupivacaine alone with intrathecal bupivacaine midazolam combination in patients undergoing elective infraumbilical surgery

Spinal anaesthesia, which is one of the techniques for infraumbilical surgeries, is most commonly criticized for limited duration of postoperative analgesia. Several adjuvants have been tried along with local anesthetic for prolonging the duration of analgesia. In this study, we have observed the effect of midazolam as an adjuvant in patients undergoing infraumbilical surgery. In this prospective, randomized, double blinded, and parallel group and open label study of 90 adult patients aged 18–60 years, of American Society of Anaesthesiologists (ASA) status I and II, scheduled for elective infraumbilical surgery, were randomly allocated in two groups. Each patient in group “B” received hyperbaric bupivacaine 12.5 mg along with 0.4 mL of normal saline in the subarachnoid block, and patients of group “BM” received 12.5 mg hyperbaric bupivacaine along with preservative free midazolam 0.4 mL (2 mg). We found that use of midazolam as adjuvant with the local anesthetic in spinal anaesthesia significantly increases the duration of analgesia (median 320 min versus 220 min) and motor block (median 255 min versus 195 min) but decreases the incidence of postoperative nausea-vomiting (PONV).

Analgesic efficacy of low-dose intrathecal neostigmine in combination with fentanyl and bupivacaine for total knee replacement surgery

Background and Aim:

Intrathecal (IT) neostigmine has been used as an adjunct to spinal anesthesia. The purpose of this study was to determine whether a combination of low-dose neostigmine IT would enhance analgesia of a fixed dose of fentanyl IT, in patients undergoing unilateral total knee replacement (TKR) surgery with spinal anesthesia.

Settings and Design:

Forty-five patients scheduled for unilateral TKR were randomized to one of the three groups (n = 15) and prospectively studied using placebo-controlled, double-blinded design.

Materials and Methods:

A 19-G epidural catheter was introduced through the L3–L4 interspace with patient in the sitting position, followed by spinal anesthesia administration through the L3–L4 interspace. Fifteen milligrams of hyperbaric bupivacaine (3 ml) plus the test drug (0.5 ml) was administered IT. The test drug was normal saline (0.5 ml) in group I; fentanyl 20 mcg (0.4 ml) and normal saline (0.1 ml) in group II; and fentanyl 20 mcg (0.4 ml) and neostigmine 1 mcg (0.1 ml) in group III. Characteristics of sensory and motor block, heart rate, and blood pressure were recorded intraoperatively. Postoperatively, pain scores, postoperative nausea and vomiting (PONV) scores, and sedation scores, and postoperative analgesic dose were recorded.

Results:

Forty-five patients were enrolled in this study and 43 patients were subjected to statistical analysis. Overall 24-h visual analog score in group III was significantly less than in those who received fentanyl alone (P = 0.00). The durations of complete analgesia and effective analgesia were longer for all patients in group III compared with group II (P < 0.05) and group I (P < 0.005) patients. The total number of epidural top ups (rescue analgesia) required was less in group II (P < 0.05) and group III (P < 0.005) patients, compared with the control group. The incidence of nausea and vomiting was not increased in group III patients.

Conclusions:

The addition of 1 mcg neostigmine IT increased the duration of analgesia and decreased the analgesic consumption in 24 h in TKR. There was no increase in the incidence of adverse effects.

Perioperative pain management in the neurosurgical patient

Perioperative pain management in neurosurgical patients has been inadequately recognized and treated. An increased awareness of pain management and advances in understanding of pain modulation and pathophysiology have led to improved perioperative care of patients. There is a need to assess neurologic function while providing superior analgesia with minimal side effects. Several classes of drugs are currently available or under investigation for use as adjuvants or alternative therapies. There remains a need to determine the best treatment of perioperative pain in this patient population. Improved awareness, assessment, and treatment of pain result in better care and overall patient outcome.

Intrathecal neostigmine with bupivacaine for infants undergoing lower abdominal and urogenital procedures: dose response

BACKGROUND

Intrathecal (IT) neostigmine produces dose-dependent analgesia in adults. However, the dose of spinal neostigmine has not been investigated in infants. The purpose of this study was to assess spinal anesthesia (SA) duration provided by four doses of spinal neostigmine added to bupivacaine for lower abdominal and urogenital procedures in infants.

METHODS

Seventy-five infants were randomized into five groups. The control group B received IT plain 0.5% hyperbaric bupivacaine. Groups BN.25, BN.50, BN.75, and BN1.0 received bupivacaine with 0.25, 0.5, 0.75, and 1 microg/kg of neostigmine, respectively. The primary variable was the duration of anesthesia assessed by recovery of hip flexion. Postoperative pain with facial expression, leg activity, arm activity, crying and consolability scale score, and rescue analgesic requirements were the secondary variables measured, and the side effects were noted.

RESULTS

Seventy-three infants completed the study. There was a significant linear increase in SA duration with IT neostigmine to 65.2 (4.3) min with 0.5 microg/kg (P<0.01), 88.2 (5.1) with 0.75 microg/kg (P<0.001) and 92 (4.3) with 1 microg/kg (P<0.001) from 52.4 (4.3) min with bupivacaine alone. SA duration showed no significant difference between plain bupivacaine and BN.25 (P=0.100) or between groups BN.75 and BN1.0 (P=0.451). Groups BN.75 and BN1.0 had significantly reduced pain scores, and the median duration before the first dose rescue analgesic was requested prolonged significantly (P<0.001) compared with the other three groups.

CONCLUSIONS

IT neostigmine at a dose of 0.75 microg/kg added to bupivacaine significantly prolonged SA duration with reduced postoperative pain scores and rescue analgesic requirements in infants undergoing lower abdominal and urogenital procedures. No additional benefits were provided on increasing it to 1 microg/kg.

Effect of lumbar epidural administration of neostigmine on lower urinary tract function

BACKGROUND

Neostigmine is cholinomimetic and is used for postoperative analgesia. Its urodynamics effects on voiding function have not been elucidated.

MATERIALS AND METHODS

Adult patients without bothersome voiding symptoms planned for rigid cystoscopy under local anesthesia were enrolled. They underwent multichannel urodynamics (filling cystometry and pressure-flow study) before and 30 min after lumbar epidural administration of Neostigmine (2 microg/kg).

RESULTS

Indications for cystoscopy were check examination for follow up of carcinoma urinary bladder (n = 3), staging for carcinoma cervix (5), and removal of ureteral stent (4). Patients' mean age was 51.9 +/- 11.7 years and international Prostatic symptom score 2.34 +/- 3.41. A trend of decreased maximum cystometric capacity (MCC) was observed after Neostigmine (413.50 +/- 142.45 ml vs. 357.00 +/- 145.62 ml; P = 0.056) without any change in end-filling pressure. Five patients developed detrusor overactivity (DO) and one had increase in its amplitude (P = 0.031). Four patients developed rhythmic rectal contractions and one had increase in its amplitude (P = 0.219). There was no difference in any of the voiding parameters. Mean Visual Analog Pain Score (VAS scale 0-10) during cystoscopy for this group was significantly lower than that in a similar group of patients who did not receive Neostigmine prior to rigid cystoscopy (1.16 +/- 0.94 vs. 4.57 +/- 1.45; P = 0.0001). The drug was well tolerated in majority of the patients.

CONCLUSION

Epidural Neostigmine is effective in providing analgesia during diagnostic rigid cystoscopy. It leads to development of DO and decrease in bladder capacity without any effect on voiding function. These findings may help clinicians to use it for transurethral procedure-related pain relief without apprehension of voiding difficulty.

Combination of low doses of intrathecal ketamine and midazolam with bupivacaine improves postoperative analgesia in orthopaedic surgery

BACKGROUND

Intrathecal ketamine produces a short period of analgesia with stable haemodynamics. Midazolam with bupivacaine prolongs the duration of analgesia when administered intrathecally but does not prevent hypotension. The objective of this study was to assess the effect of a combination of intrathecal bupivacaine, ketamine and midazolam on the duration of analgesia and haemodynamic parameters.

METHODS

A prospective, randomized, double-blind study was carried out in 60 ASA I and II patients undergoing lower limb surgery under spinal anaesthesia. Patients were divided into three groups of 20 each. Patients in all the three groups received 3 mL of hyperbaric bupivacaine (0.5%) intrathecally. In addition, patients in Groups II and III received intrathecal ketamine (0.1 mg kg-1) and the same dose of ketamine along with midazolam (0.02 mg kg-1), respectively. All patients were evaluated for block characteristics, duration of pain-free period, total rescue analgesic requirement in the 24-h postoperative period, total dose of mephenteramine to treat hypotension and any central or neurological complication.

RESULTS

No patients in Group II required mephenteramine while 40% of patients in Group I and 10% in Group III required mephenteramine to maintain blood pressure after spinal anaesthesia. The mean +/- standard deviation duration of pain-free period was 331.5 +/- 89.9, 369.7 +/- 124.2 and 730.5 +/- 81.5 min in Group I, II and III, respectively. The pain-free interval was significantly greater in Group III compared to Groups I and II (P < 0.001). No patient had any complications.

CONCLUSION

A low dose of midazolam and ketamine with bupivacaine intrathecally results in prolonged analgesia and less haemodynamic fluctuations. However, the safety of this combination needs to be proved before its use in clinical practice.

Perioperative pain management in the neurosurgical patient

The perioperative management of pain in neurosurgical patients is a controversial topic with management decisions based mainly on reports of anecdotal experiences. There is no consensus regarding the standardization of pain control in this patient population. In the last decade, improved awareness and advances in the practice of pain management have resulted in the implementation of diverse techniques to achieve adequate analgesia in this undertreated group of patients. This article provides information about the various techniques and approaches, based on the latest research and clinical trials conducted in this patient population. Specifically, the physiology of pain in patients undergoing brain or spine surgery, the different modalities for pain control, and the diverse choice of drugs, with their associated risks and benefits, are reviewed.

Modern concepts of acute and chronic pain management

Both, acute and chronic pain should be treated using appropriate pain management as they may cause several negative reactions and jeopardise the health or at least the quality of life of the patients. Nowadays there are many analgesics and treatment tools available to provide sufficient pain relief for almost all patients. Unfortunately there are still patients suffering from pain due to inadequate or/and inconsequent pain therapy.

The efficacy of thoracic epidural neostigmine infusion after thoracotomy

Few anesthesia studies have explored perioperative continuous epidural infusion of neostigmine. We examined such a regimen in thoracotomy patients. Ninety patients were randomized to one of three groups in this double-blind trial. Before anesthesia induction, an epidural catheter was inserted in all patients at T5-8 levels under local anesthesia. Pre-neo patients received bolus 500-microg epidural neostigmine before anesthesia induction followed by infusion of 125 microg/h until the end of surgery. Post-neo patients received epidural saline during the same time periods plus bolus 500-microg epidural neostigmine at end of surgery. Patients in the control group received saline placebo during all three periods. Patients in the neostigmine groups postoperatively received patient-controlled epidural analgesia with morphine 0.02 mg/mL, bupivacaine 0.08 mg/mL, and neostigmine 7 microg/mL. Control patient-controlled epidural analgesia excluded neostigmine. Data were recorded for 6 postoperative days. Daily patient-controlled epidural analgesia consumption (mL) for Pre-neo patients was significantly less than that of post-neo and control group patients for postoperative days 1-6 (at least 10% and 16% less, respectively; P < 0.05). There was a modest decrease in pain intensity on postoperative days 3-6 for pre-neo patients versus other groups (P < 0.05). These results suggest that continuous thoracic epidural neostigmine started before anesthesia provided preemptive, preventive analgesia and an analgesic-sparing effect that improved postoperative analgesia for these patients without increasing the incidence of adverse effects.

The role of intrathecal drugs in the treatment of acute pain

Intrathecal opioids are widely used as useful adjuncts in the treatment of acute and chronic pain, and a number of non-opioid drugs show promise as analgesic drugs with spinal selectivity. In this review we examine the historical development and current use of intrathecal opioids and other drugs that show promise for treating pain in the perioperative period. The pharmacology and clinical use of intrathecal morphine and other opioids is reviewed in detail, including dosing guidelines for specific surgical procedures and the incidence and treatment of side effects associated with these drugs. Available data on the use of non-opioid drugs that have been tested intrathecally for use as analgesics are also reviewed. Evidence-based guidelines for dosing of intrathecal drugs for specific surgical procedures and for the treatment of the most common side effects associated with these drugs are presented.

Caudal additives for postoperative pain management in children: S(+)-ketamine and neostigmine

BACKGROUND

The aim of the present pilot study was to compare the analgesic efficacy of S(+)-ketamine either alone or in combination with neostigmine for caudal blockade in pediatric surgery.

METHODS

A total of 40 children were randomly assigned to receive after induction of general anesthesia either caudal S(+)-ketamine 1 mg.kg(-1) (group K, n = 20) or caudal S (+)-ketamine 0.5 mg.kg(-1) plus neostigmine 10 microg.kg(-1) (group KN, n = 20). Anesthesia was maintained with sevoflurane and a laryngeal mask airway (LMA), no additional analgesics were administered. Postoperative pain and sedation were assessed by the Children's Hospital of Eastern Ontario Pain Score and Ramsay scale for 24 h.

RESULTS

No statistical difference in duration of analgesia and sedation was found. Mean duration of postoperative analgesia was 18 +/- 9.4 h in group K and 21.8 +/- 6.7 h in group KN. There was a significantly higher incidence of postoperative vomiting after administration of caudal ketamine with neostigmine (30% group KN Vs 0% group K; P < 0.05).

CONCLUSIONS

This pilot study demonstrates equianalgesic effects on postoperative pain relief in children with both caudal S(+)-ketamine 1 mg.kg(-1) and caudal S(+)-ketamine 0.5 mg.kg(-1) plus neostigmine 10 microg.kg(-1). Further studies are required to confirm adoption of caudal neostigmine into routine clinical practice.

Intrathecal midazolam added to bupivacaine improves the duration and quality of spinal anaesthesia

BACKGROUND

The antinociceptive action of intrathecal midazolam is well documented. In this prospective study, we investigated the addition of midazolam to intrathecal bupivacaine on the duration and quality of spinal blockade.

METHODS

Forty ASA I or II adult patients undergoing lower abdominal surgery were selected for the study. The patients were randomly allocated to receive 3 ml of 0.5% hyperbaric bupivacaine intrathecally either alone or with 1 mg of midazolam using a combined spinal epidural technique. The duration and quality of sensory and motor block, perioperative analgesia, haemodynamic changes, and sedation levels were assessed.

RESULTS

The duration of sensory block (i.e. time to regression to the S2 segment) was significantly longer in the midazolam group than the control group (218 min vs. 165 min; P < 0.001). The duration of motor block was also prolonged in the midazolam group as compared with the control group (P < 0.01). In 90% of the patients in the midazolam group, the quality of block was adequate during the intra-operative period as compared with only 65% of the patients in the control group (P < 0.05). The duration of effective analgesia was longer in the midazolam group than in the control group (199 vs. 103 min; P < 0.001). Blood pressure, heart rate, oxygen saturation and sedation scores were comparable in both groups. No neurological deficit or other significant adverse effects were recorded.

CONCLUSION

The addition of intrathecal midazolam to bupivacaine significantly improves the duration and quality of spinal anaesthesia and provides prolonged perioperative analgesia without significant side-effects.

Epidural morphine and neostigmine for postoperative analgesia after orthopedic surgery

In this study, we examined the side effects and analgesia of the combination of epidural neostigmine and morphine in patients undergoing orthopedic surgery. Sixty patients undergoing knee surgery were divided into four groups. The intrathecal anesthetic was 15 mg of bupivacaine. The epidural test drug was diluted in saline to a final volume of 10 mL. The control group received saline as the epidural test drug. The morphine group received 0.6 mg of epidural morphine. The neostigmine group (NG) received 60 micro g of epidural neostigmine. The morphine/neostigmine group received 0.6 mg of epidural morphine combined with 60 micro g of epidural neostigmine. The groups were demographically the same and did not differ in intraoperative characteristics. The visual analog scale score at first rescue analgesic and the incidence of adverse effects were similar among groups (P > 0.05). One patient from the NG complained of intraoperative nausea, closely related to spinal hypotension. Postoperatively, two patients from the NG had vomited once. The time (min) to first rescue analgesic was longer in the morphine/neostigmine group ( approximately 11 h) compared with the other groups (P < 0.05). The analgesic consumption (number of analgesic administrations in 24 h) was larger in the control group compared with the other groups (P < 0.05).

IMPLICATIONS

The combination of epidural morphine and epidural neostigmine resulted in postoperative analgesia (11 h) devoid of side effects, being an alternative analgesic technique in the population studied.

Caudal neostigmine, bupivacaine, and their combination for postoperative pain management after hypospadias surgery in children

In a randomized, double-blinded study, we examined the analgesic efficacy of caudal neostigmine, bupivacaine, or a mixture of both drugs in 60 children. After the induction of general anesthesia, children were allocated randomly into three groups (n = 20) to receive a caudal injection of either 0.25% bupivacaine 1 mL/kg, with or without neostigmine 2 micro g/kg, or neostigmine 2 micro g/kg in normal saline 1 mL/kg. Intraoperatively, children receiving caudal bupivacaine or a bupivacaine/neostigmine mixture maintained hemodynamic stability, required less inhaled anesthetics, and had a shorter recovery time compared with the caudal neostigmine alone. Postoperatively, the caudal bupivacaine/neostigmine mixture resulted in superior analgesia compared with the other two groups. Recovery to first rescue analgesic times were (mean +/- SD) 22.8 +/- 2.9 h, 8.1 +/- 5.9 h, and 5.2 +/- 2.1 h in the bupivacaine/neostigmine, bupivacaine, and neostigmine groups, respectively (P < 0.001). In addition, the bupivacaine and neostigmine groups received more doses of paracetamol than the bupivacaine/neostigmine group to maintain adequate analgesia in the first 24 postoperative h. Postoperative vomiting occurred in 25%, 10%, and 30% in the caudal bupivacaine/neostigmine, bupivacaine, and neostigmine groups, respectively (P < 0.01). We conclude that caudal neostigmine 2 micro g/kg provides postoperative analgesia comparable to caudal bupivacaine in children undergoing hypospadias repair surgery.

IMPLICATIONS

Caudal neostigmine 2 micro g/kg provides postoperative analgesia comparable to caudal bupivacaine in children undergoing hypospadias repair surgery. Co-administration of the two drugs is associated with extended postoperative analgesia and reduced need for supplementary analgesics.

Spinal anaesthesia: local anaesthetics and adjuncts in the ambulatory setting

Intrathecal lidocaine remains a popular choice for ambulatory spinal anaesthesia due to its reliability, rapid onset and predictable rapid recovery profile. However, concerns with transient neurological symptoms (TNS) and their significant association with lidocaine have generated interest in alternative local anaesthetic agents to provide adequate spinal anaesthesia with the briefest possible recovery period. This chapter updates current data on drug dose-response relationships for local anaesthetics and the increasing use of intrathecal adjuncts to improve the anaesthetic and recovery profile for ambulatory spinal anaesthesia. Newer spinal anaesthetic techniques for common ambulatory procedures highlight the success of combining subclinical doses of local anaesthetics and intrathecal adjuncts. Controversies regarding the possible lower risk of TNS with newer spinal anaesthetic techniques and new discharge criteria are reviewed. The final section provides technical pearls to optimize ambulatory spinal anaesthetic outcomes.

Intrathecal administration of liposomal neostigmine prolongs analgesia in mice

BACKGROUND

There is substantial evidence that cholinomimetic drugs increase pain threshold. However, the profound side effects of these agents have limited their clinical use either as analgesics or as analgesic adjuncts. A delivery system that would assure a slow and sustained drug release may be of value in ameliorating the problem of untoward effects.

METHODS

The acetylcholinesterase inhibitor neostigmine was encapsulated into multilamellar lipid vesicles composed of phosphocholine and cholesterol. Three doses of plain or liposomal neostigmine were administered by the intrathecal route to mice (n=8-10/group), and analgesic duration was quantified by tail flick test. The doses were chosen based on preliminary experiments, which showed the maximum tolerated intrathecal doses of plain and liposomal neostigmine formulation were 0.625 microg and 80 microg, respectively. Two other doses for each formulation were then derived by 1:1 serial dilutions. Results were compared using survival analysis.

RESULTS

The median antinociceptive duration for plain neostigmine was 0.33, 0.99 and 1.0 h for the 0.115, 0.312 and 0.625 microg doses, respectively. For the liposomal formulation, the median antinociceptive duration was 1.0, 1.5 and 6.0 h for the 20, 40 and 80 microg doses, respectively.

CONCLUSIONS

Liposomal neostigmine provides prolonged spinal antinociception, and permits the safe administration of a relatively large dose, because drug is gradually released from the liposomal depot. This technology holds promise for the development of a clinically useful neostigmine formulation to provide spinal analgesia.

Intrathecal bupivacaine with morphine or neostigmine for postoperative analgesia after total knee replacement surgery

PURPOSE

To compare the postoperative analgesic efficacy and safety of intrathecal (IT) neostigmine and IT morphine in patients undergoing total knee replacement under spinal anesthesia.

METHODS

Sixty patients scheduled for elective total knee replacement under spinal anesthesia were randomly divided into three equal groups which received IT 0.5% hyperbaric bupivacaine 15 mg with either normal saline 0.5 mL, neostigmine 50 microg, or morphine 300 microg. The maximal level of sensory block, duration of analgesia, time to use of rescue analgesics, the overall 24-hr and four-hour interval visual analogue scale (VAS) pain score, and the incidence of adverse effects were recorded for 24 hr after administration.

RESULTS

There was no significant difference in maximal level of sensory block among the three groups. The morphine group had a later onset of postsurgical pain and longer time to first rescue analgesics than the neostigmine group (P <0.05). Overall 24-hr VAS pain scores were significantly higher in the saline group vs the morphine and neostigmine groups (P <0.05). Motor block lasted significantly longer in the neostigmine group than in the morphine and saline groups (P <0.05). The incidence of adverse effects was similar in the neostigmine and morphine groups except for pruritus (70%) occurring more frequently in the morphine group than in the neostigmine and saline groups (0%; P <0.05). Overall satisfaction rates were better in the neostigmine group than in the morphine and saline groups (P <0.05).

CONCLUSIONS

IT neostigmine 50 microg produced postoperative analgesia lasting about seven hours with fewer side effects and better satisfaction ratings than IT morphine 300 microg.

Efficacy of intrathecal neostigmine for the relief of postinguinal hemiorrhaphy pain

BACKGROUND

Intrathecal administration of various doses of neostigmine has been reported to produce analgesia without neurotoxicity in both animal and human studies. The present study was undertaken to evaluate the efficacy and safety of intrathecal neostigmine for the relief of pain for patients having undergone inguinal herniorrhaphy surgery.

METHODS

Sixty men scheduled for elective inguinal herniorrhaphy with spinal anaesthesia were randomly allocated to three groups: group I (n=20) received intrathecal (IT) tetracaine 15 mg, group II (n=20) received IT tetracaine 15 mg+ neostigmine 50 microg, and group III (n=20) received IT tetracaine 15 mg+neostigmine 100 microg. The onset of anaesthesia, duration of analgesia, time to use of first rescue analgesics, the overall 24 h VAS pain scores and the incidence of adverse effects were recorded for 24 h postdrug administration.

RESULTS

Onset of anaesthesia (time to T6 sensory block) was significantly faster for group II and III patients compared with group I patients. Motor block (time to lift leg) was greatly prolonged for group III patients, with an average of 6.4 h, compared with 4.1 h for group II patients. Group III patients also showed a later onset of postsurgical pain, lower overall 24-h VAS pain score and prolonged time to first rescue analgesics than did group II patients. There was a significantly greater incidence of adverse effects associated with IT neostigmine, especially nausea and vomiting.

CONCLUSION

Our study showed that intrathecal neostigmine at 50 pg or 100 microg enhanced the onset of tetracaine anaesthesia and provided analgesia lasting for 6-9 h, although increased incidences of prolonged motor blockade and nausea or vomiting were noted.

Effects of intrathecal ketamine added to bupivacaine for spinal anaesthesia

We prospectively studied 30 healthy female patients undergoing intracavitory brachytherapy applicator insertion for carcinoma of the cervix under spinal anaesthesia. Patients were randomly allocated to receive either intrathecal bupivacaine 10 mg alone or bupivacaine 7.5 mg combined with preservative-free ketamine 25 mg. Spinal block onset, maximum sensory level, duration of blockade, haemodynamic variables, postoperative analgesic requirements and adverse events were recorded. Onset of sensory and motor block and duration of spinal analgesia were comparable between groups. Duration of motor blockade was shorter (p = 0.0416) and requirement for intravenous fluids in the peri-operative period was less (p = 0.0159) in the ketamine group. Significantly more patients in the ketamine group had adverse events, such as sedation, dizziness, nystagmus, 'strange feelings' and postoperative nausea and vomiting. Although the addition of ketamine to spinal bupivacaine had local anaesthetic sparing effects, it did not provide extended postoperative analgesia or decrease the postoperative analgesic requirements. Moreover, the central adverse effects of ketamine limit its spinal application.

New developments in spinal anesthesia

Spinal anesthesia can be used effectively and efficiently for a variety of cases in both the inpatient and the ambulatory surgery setting. Choice of agent, dose, distribution, use of adjuncts, and occasionally the use of continuous spinal anesthesia can tailor the spinal anesthetic to a specific type and duration of surgery. Although spinal anesthesia is extremely safe, adherence of new guidelines for patients receiving anticoagulant drugs, LMWH in particular, may minimize the risk of neurologic injury from spinal bleeding. At present, intrathecal adjuncts, such as neostigmine and clonidine used with local anesthetics, have shown limited usefulness, whereas lipophilic opioids, such as fentanyl, appear to increase duration and quality of spinal block without increasing the time to recovery. In the future, shorter-acting local anesthetics, possibly in conjunction with continuous catheter technologies, may reduce recovery times after spinal anesthesia without increasing risk. Spinal agents with long-acting analgesic properties that do not produce sensorimotor deficits may go beyond the immediate perioperative period and relieve postoperative pain. Currently there is controversy surrounding the use of spinal lidocaine and the occurrence of TNS, especially in the outpatient setting. The prudent use of small-dose bupivacaine and possibly procaine may reduce this risk, further supporting the use of spinal anesthesia for ambulatory as well as inpatient surgical procedures.