Intrathecal pethidine: pharmacology and clinical applications

Adequate Anesthesia and More Effective Analgesia by Adjusted Doses of Bupivacaine during Cesarean Section: A Randomized Double-blind Clinical Trial

Background

Several adjuvants, added to local anesthetics, were suggested to induce an ideal regional block with high-quality analgesia. The purpose of this study was to evaluate the particular blocking properties of low-dose bupivacaine in combination with meperidine and fentanyl in spinal anesthesia during Cesarean sections.

Methods

A randomized, double-blind clinical trial was conducted at Hafez Hospital affiliated with Shiraz University of Medical Sciences (Shiraz, Iran) from February 2015 to February 2016. A total of 120 pregnant women, who underwent spinal anesthesia during elective Cesarean section were enrolled in the study. Based on block-wise randomization, the patients were randomly assigned to three groups, namely "B" group received 2 mL bupivacaine 0.5% (10 mg), "BM" group received 8 mg bupivacaine and 10 mg meperidine, and "BF" group received 8 mg bupivacaine and 15 µg fentanyl intrathecally. The block onset, the duration of analgesia, and the time of discharge from the post-anesthesia care unit (PACU) were all assessed. Data were analyzed using SPSS software version 21, and P<0.05 were considered statistically significant.

Results

The mean duration of motor blocks in the B group (150 min) were significantly higher than the BM (102 min) and BF (105 min) groups (P<0.0001). In both the BM and BF groups, the duration of sensory and motor blocks was the same. The length of stay in the PACU was significantly longer in the B group (P<0.001) than the BM and BF groups. When meperidine or fentanyl was added to bupivacaine, the duration of the analgesia lengthened (P<0.001).

Conclusion

Intrathecal low-dose spinal anesthesia induced by bupivacaine (8 mg) in combination with meperidine and/or fentanyl for Cesarean section increased maternal hemodynamic stability, while ensuring effective anesthetic conditions, extending effective analgesia, and reducing the length of stay in PACU.Trial Registration Number: IRCT2015013119470N14.

The Analysis of Pethidine Pharmacokinetics in Newborn Saliva, Plasma, and Brain Extracellular Fluid After Prenatal Intrauterine Exposure from Pregnant Mothers Receiving Intramuscular Dose Using PBPK Modeling

BACKGROUND AND OBJECTIVE

Pethidine (meperidine) can decrease labor pain-associated mother's hyperventilation and high cortisol-induced newborn complications. However, prenatal transplacentally acquired pethidine can cause side effects in newborns. High pethidine concentrations in the newborn brain extracellular fluid (bECF) can cause a serotonin crisis. Therapeutic drug monitoring (TDM) in newborns' blood distresses them and increases infection incidence, which can be overcome by using salivary TDM. Physiologically based pharmacokinetic (PBPK) modeling can predict drug concentrations in newborn plasma, saliva, and bECF after intrauterine pethidine exposure.

METHODS

A healthy adult PBPK model was constructed, verified, and scaled to newborn and pregnant populations after intravenous and intramuscular pethidine administration. The pregnancy PBPK model was used to predict the newborn dose received transplacentally at birth, which was used as input to the newborn PBPK model to predict newborn plasma, saliva, and bECF pethidine concentrations and set correlation equations between them.

RESULTS

Pethidine can be classified as a Salivary Excretion Classification System class II drug. The developed PBPK model predicted that, after maternal pethidine intramuscular doses of 100 mg and 150 mg, the newborn plasma and bECF concentrations were below the toxicity thresholds. Moreover, it was estimated that newborn saliva concentrations of 4.7 µM, 11.4 µM, and 57.7 µM can be used as salivary threshold concentrations for pethidine analgesic effects, side effects, and the risk for serotonin crisis, respectively, in newborns.

CONCLUSION

It was shown that saliva can be used for pethidine TDM in newborns during the first few days after delivery to mothers receiving pethidine.

Analgesic Alkaloids Derived From Traditional Chinese Medicine in Pain Management

Chronic pain is one of the most prevalent health problems. The establishment of chronic pain is complex. Current medication for chronic pain mainly dependent on anticonvulsants, tricyclic antidepressants and opioidergic drugs. However, they have limited therapeutic efficacy, and some even with severe side effects. We turned our interest into alkaloids separated from traditional Chinese medicine (TCM), that usually act on multiple drug targets. In this article, we introduced the best-studied analgesic alkaloids derived from TCM, including tetrahydropalmatine, aloperine, oxysophocarpine, matrine, sinomenine, ligustrazine, evodiamine, brucine, tetrandrine, Stopholidine, and lappaconitine, focusing on their mechanisms and potential clinical applications. To better describe the mechanism of these alkaloids, we adopted the concept of drug-cloud (dCloud) theory. dCloud illustrated the full therapeutic spectrum of multitarget analgesics with two dimensions, which are “direct efficacy”, including inhibition of ion channels, activating γ-Aminobutyric Acid/opioid receptors, to suppress pain signal directly; and “background efficacy”, including reducing neuronal inflammation/oxidative stress, inhibition of glial cell activation, restoring the balance between excitatory and inhibitory neurotransmission, to cure the root causes of chronic pain. Empirical evidence showed drug combination is beneficial to 30–50% chronic pain patients. To promote the discovery of effective analgesic combinations, we introduced an ancient Chinese therapeutic regimen that combines herbal drugs with “Jun”, “Chen”, “Zuo”, and “Shi” properties. In dCloud, “Jun” drug acts directly on the major symptom of the disease; “Chen” drug generates major background effects; “Zuo” drug has salutary and supportive functions; and “Shi” drug facilitates drug delivery to the targeted tissue. Subsequently, using this concept, we interpreted the therapeutic effect of established analgesic compositions containing TCM derived analgesic alkaloids, which may contribute to the establishment of an alternative drug discovery model.

A Post-Marketing Study of Pethidine in Indonesia: Safety Profile

Introduction Pethidine along with morphine and tramadol, is one of the frequently used drugs for postoperative pain management. It is important to ensure the safety of the product and ultimately the safety of the patients as users of the pethidine. Methods A post marketing surveillance study was conducted with a retrospective cross-sectional design using medical records and hospital pharmacy’s data in patients who were admitted to inpatient or emergency department of Dr. Sardjito General Hospital Yogyakarta between January and December 2016. The data was analyzed descriptively to estimate the proportion of adverse events (AEs) including serious adverse events (SAE). Results Of the 576 patients hospitalized at the at the Dr. Sardjito General Hospital, 200 medical records were selected using consecutive sampling method. A total of 120 of the 200 subjects were found to have 245 any Adverse Events (AE) including Serious Adverse Events (SAE) following the administration of pethidine. There were 23 classifications of expected AE and 148 classifications of unexpected AE following the administration of pethidine. The duration of AE/SAE found ranged from 0 to 11 days. A total of 101 (50.5%) and 85 (42.5%) subjects experienced AE/SAE with duration <24 hours and between 1 to 2 days, respectively. The longest duration of event was pain with duration of 11 days. There were 23 types of expected AE/SAE from pethidine found in subjects, with the highest number of expected AE/SAE were weakness, vomiting, and dizziness of 24 (25%), 16 (16.8%), and 10 (10.5%), respectively. The expert panel team concluded five types of unexpected SAEs which are possible to pethidine, including respiratory acidosis, urinary tract infections, acute kidney injury, icteric, and electrolyte imbalance. Conclusion A post-marketing surveillance study provides safety profile of 50 mg / ml pethidine in Indonesia. A total of 120 of the 200 subjects who received pethidine experienced 245 Adverse Events (AEs) or Serious Adverse Events (SAEs). AEs/SAEs were divided into 23 types of expected events and 148 types of unexpected events. Few numbers of SAEs were considered possible related to the pethidine according to expert panel review.   Keywords: pethidine, meperidine, post-marketing, pharmacovigilance

The Effectiveness of Caudal Block with Low Doses of Dexmedetomidine and Pethidine in Transrectal Prostate Biopsy: Preliminary Results

PURPOSE

To evaluate the effectiveness of caudal block (CB) using dexmedetomidine and pethidine instead of local anesthesia (LA) for prostate needle biopsy and the effect of CB on urinary retention.

MATERIAL AND METHODS

A transrectal ultrasound-guided prostate needle biopsy (TRUS-Bx) was performed on 68 patients with a mean age of 65 ± 2.18 years. CB with a combination of dexmedetomidine and pethidine without LA was administered to the patients. The pain levels of the patients were determined using numeric rating scale (NRS) scores to evaluate the effectiveness of CB. Preoperative and postoperative postvoid residual urine volumes (PRUV) were also calculated.

RESULTS

The CB success rate was 93.15%. The NRS scores were 0.79 ± 0.19 and 0.89 ± 0.22 during probe entry and manipulation and biopsy, respectively, without any significant differences between them (p = 0.382). The mean PRUVs before and after biopsy did not differ significantly (41 ± 15.6 vs. 71.93 ± 22.3, p = 0.379). The degree of sedation, as assessed using the Ramsay scale, was 2 or 3 in all patients.

CONCLUSION

The combination of dexmedetomidine and pethidine for CB in TRUS-Bx provided quality analgesia for the patient and prevented the development of postoperative urinary retention.

Effect of intrathecal lipophilic opioids on the incidence of shivering in women undergoing cesarean delivery after spinal anesthesia: a systematic review and bayesian network meta- analysis of randomized controlled trials

Background

Shivering is a common side effect in women having cesarean delivery (CD) under spinal anesthesia, which can be bothersome to the patient, and it can also interfere with perioperative monitoring. In several studies, the intrathecal (IT) addition of a lipophilic opioid to local anesthetics has been shown to decrease the incidence of shivering.

Objective

We performed this network meta-analysis to evaluate the effects of intrathecal lipophilic opioids in preventing the incidence of shivering in patients undergoing CD.

Methods

This review was planned according to the PRISMA for Network Meta-Analysis (PRISMA-NMA) guidelines. An English literature search of multiple electronic databases was conducted. We included randomized controlled trials (RCTs) that reported on the incidence of shivering, with study groups receiving either IT fentanyl, sufentanil, or meperidine in women undergoing CD under spinal anesthesia. Quality of the studies was assessed using the modified Oxford scoring system. Using random-effects modeling, dichotomous data were extracted and summarized using odds ratio (OR) with a 95% credible interval (CrI). Statistical analysis was conducted using R studio version 1.0.153 - Inc.

Results

Twenty-one studies consisting of 1433 patients (Control group: 590 patients in twenty-one studies; Fentanyl group:199 patients in seven studies; Sufentanil group: 156 patients in five studies; Meperidine group: 488 patients in ten studies) met the inclusion criteria for this systematic review investigating the effect of intrathecal lipophilic opioids in preventing the incidence of shivering in women undergoing cesarean delivery under spinal anesthesia. Methodological validity scores ranged from 3 to 7. The Bayesian mixed network estimate showed the incidence of shivering was significantly lower with IT fentanyl (pooled odds ratio (OR): 0.13; 95% credible interval (CrI): 0.04 to 0.35; P = 0.0004) and IT meperidine (OR: 0.12; 95% CrI: 0.05 to 0.29; P < 0.00001), but not with IT sufentanil (OR: 0.37; 95% CrI: 0.11 to 1.22; P = 0.23). The IT fentanyl group had a significantly lower incidence of intraoperative discomfort [Risk Ratio (RR): 0.19; 95% CI: 0.10–0.35; P < 0.00001], the IT sufentanil group had a significantly higher incidence of pruritus (RR: 6.18; 95% CI: 1.18–32.46; P = 0.03) The IT meperidine group had a significantly lower incidence of intraoperative discomfort (2.7% vs. 13.6%; RR: 0.22; 95% CI: 0.09–0.55; P = 0.001), but there was a significant increase in nausea and vomiting (IT meperidine group vs. Control group: 42.7% vs. 19.4%; RR: 2.56; 95% CI: 1.14–5.75; P = 0.02). Meta-regression analysis based on the opioid dose and quality of the study did not impact the final inference of our result.

Conclusion

IT fentanyl significantly decreased the incidence of shivering in women undergoing CD under spinal anesthesia without increasing maternal adverse events, confirming that routine use in this patient population is a good choice. IT sufentanil did not decrease the incidence of shivering. IT meperidine decreased the incidence and severity of shivering, but its use was also associated with significant nausea and vomiting.

Preventing shivering with adjuvant low dose intrathecal meperidine: A meta-analysis of randomized controlled trials with trial sequential analysis

The aim of this systematic review and meta-analysis is to evaluate the pros and cons of adjuvant low dose intrathecal meperidine for spinal anaesthesia. We searched electronic databases for randomized controlled trials using trial sequential analysis (TSA) to evaluate the incidence of reduced rescue analgesics, shivering, pruritus, nausea and vomiting when applying adjuvant intrathecal meperidine. Twenty-eight trials with 2216 patients were included. Adjuvant intrathecal meperidine, 0.05-0.5 mg kg-1, significantly reduced incidence of shivering (relative risk, RR, 0.31, 95% confidence interval, CI, 0.24 to 0.40; TSA-adjusted RR, 0.32, 95% CI, 0.25 to 0.41). Intrathecal meperidine also effectively reduced need for intraoperative rescue analgesics (RR, 0.27, 95% CI, 0.12 to 0.64; TSA-adjusted RR, 0.27, 95% CI, 0.08 to 0.91) and the incidence of pruritus was unaffected (RR, 2.31, 95% CI, 0.94 to 5.70; TSA-adjusted RR, 1.42, 95% CI, 0.87 to 2.34). However, nausea and vomiting increased (RR, 1.84, 95% CI, 1.29 to 2.64; TSA-adjusted RR, 1.72, 95% CI, 1.33 to 2.23; RR, 2.23, 95% CI, 1.23 to 4.02; TSA-adjusted RR,1.96, 95% CI, 1.20 to 3.21). Under TSA, these results provided a sufficient level of evidence. In conclusion, adjuvant low dose intrathecal meperidine effectively attenuates spinal anaesthesia-associated shivering and reduces rescue analgesics with residual concerns for the nausea and vomiting.

The effect of intra-articular meperidine and bupivacaine 0.5% on postoperative pain of arthroscopic knee surgery; a randomized double blind clinical trial

Background:

Arthroscopic knee surgeries have a painful postoperative course, which often necessitates acute pain management. Among different analgesia techniques, Intra-articular injection is the technique of choice for many pain specialists, based on its confined effect to the surgical site (knee), lack of systemic effects and promotion of safe early ambulation.

Objectives:

The aim of this study was to compare analgesic effects of intra-articular meperidine, bupivacaine 0.5% or their combination after knee arthroscopic surgery.

Patients and Methods:

Sixty ASA class I-II patients’ candidates for arthroscopy knee surgery enrolled in a randomized double blind study to receive either 20 mL of bupivacaine 0.5%; 100 mg meperidine (diluted in normal saline) or bupivacaine 0.5% along with 100 mg meperidine. A written informed consent was obtained from all patients. Postoperative analgesia duration, VAS at 2, 6, 12 and 24 hours, the first analgesic request time, total fentanyl consumption in first 24 hours, patients’ satisfaction and adverse effects were recorded.

Results:

The bupivacaine-meperidine group had better duration of postoperative analgesia (P = 0.001), latter first analgesic request (P ≤ 0.001), lower total fentanyl consumption in first 24 hours after the operation (P = 0.001), less mean VAS at 2 hours (P = 0.001) and more patients’ overall satisfaction (P = 0.01) compared with each medication alone. VAS at 6, 12 and 24 postoperative hours were not different between the groups of study. No adverse effects were observed.

Conclusions:

Although postoperative intra-articular meperidine is a better alternative for bupivacaine, their combination could improve their analgesic effects compared with each other alone.

Does dexamethasone prevent subarachnoid meperidin-induced nausea, vomiting and pruritus after cesarean delivery?

Background:

Opioid-induced side effects such as nausea and vomiting and pruritus are common and may be more debilitating than pain itself. We performed a study to assess the efficacy of dexamethasone in reducing postoperative nausea, vomiting, and pruritus in patients receiving neuraxial anesthesia with meperidine.

Methods:

Fifty-two women undergoing cesarean section were enrolled in the study. The control group and dexamethasone group received intravenously normal saline and dexamethasone, respectively, before spinal anesthesia. The occurrence of postoperative nausea, vomiting, and pruritus was assessed for 24 h in both groups.

Results:

The overall incidence of nausea and vomiting during the 24 h follow-up period was 37% and 22.2% for group saline and 20% and 12% for group dexamethasone, respectively (P=0.175, 0.469). The incidence of pruritus was not significantly different between the two groups. Pruritus severity was significantly less in the dexamethasone group than in the saline group (P=0.019).

Conclusion:

Prophylactic dexamethasone does not reduce the incidence of subarachnoid meperidine-induced nausea, vomiting, and pruritus in women undergoing cesarean delivery.

Spinal pethidine for elective caesarean section

Pethidine (meperidine) is a unique member of the opioid family. In addition to its analgesic activity, it also has significant local anaesthetic activity. This property enables it to be used as the sole agent for spinal anaesthesia. We describe the successful use of intrathecal pethidine 1 mg/kg for an elective lower segment caesarean section in a patient presumed to be allergic to amide local anaesthetics. There were no significant adverse effects in either the mother or the newborn.

Combining Intrathecal Bupivacaine and Meperidine during Caesarean Section to Prevent Spinal Anaesthesia-Induced Hypotension and other Side-Effects

This study compared intrathecal hyperbaric bupivacaine with low-dose intrathecal plain bupivacaine plus different doses of meperidine (pethidine), administered sequentially, with regard to blood pressure stability, post-operative analgesia and incidence of side-effects in 80 parturients undergoing caesarean section. Patients were randomly assigned to one of four groups ( n = 20 each group): the HB group received 10 mg hyperbaric bupivacaine intrathecally; the BM35, BM30 and BM25 groups received 5 mg plain bupivacaine plus 35, 30 or 25 mg of meperidine intrathecally, respectively. The incidence of hypotension in the BM25 group was significantly lower than in the HB group. Nausea and vomiting were less prevalent in the BM25 group than in the HB and BM35 groups. In conclusion, sequential administration of 5 mg plain bupivacaine and 25 mg meperidine intrathecally provided better blood pressure stability and a lower incidence of side-effects than bupivacaine alone, without affecting quality of anaesthesia or surgical and patient satisfaction.

Low-dose spinal anaesthesia for caesarean section

PURPOSE OF REVIEW

The literature on the appropriate dose of local anaesthetic and combinations with opioids for spinal anaesthesia for caesarean section in patients without comorbid conditions is reviewed. The controversial issue of spinal anaesthesia in severe preeclampsia is also addressed.

RECENT FINDINGS

Recent comparisons with ropivacaine and levobupivacaine suggest that bupivacaine remains the best agent for spinal anaesthesia for caesarean section. The addition of various combinations of opioids has allowed a reduction in the dose of bupivacaine. Intrathecal diamorphine has been extensively investigated and appears to have a favourable pharmacokinetic and pharmacodynamic profile. In severe preeclampsia, spinal anaesthesia may be associated with less hypotension than in healthy parturients, where similar doses of local anaesthetic are used.

SUMMARY

Low-dose spinal anaesthesia has been advocated in the interests of improving cardiovascular stability. However, current sophistication of knowledge concerning spinal anaesthetic technique makes cardiovascular instability easy to prevent. Therefore this review emphasizes the importance of adequate surgical anaesthesia during caesarean section, and makes suggestions as to the optimal pharmacological agents for intraoperative anaesthesia and postoperative analgesia. Spinal anaesthesia is safe in severe preeclampsia, provided there are no contraindications to regional anaesthesia.

Neuraxial drug administration: a review of treatment options for anaesthesia and analgesia

Neuraxial drug administration describes techniques that deliver drugs in close proximity to the spinal cord, i.e. intrathecally into the CSF or epidurally into the fatty tissues surrounding the dura, by injection or infusion. This approach was initially developed in the form of spinal anaesthesia over 100 years ago. Since then, neuraxial drug administration has evolved and now includes a wide range of techniques to administer a large number of different drugs to provide anaesthesia, but also analgesia and treatment of spasticity in a variety of acute and chronic settings. This review concentrates on the pharmacological agents used and the clinical basis behind currently utilised approaches to neuraxial drug administration. With regard to local anaesthetics, the main focus is on the development of the enantiomer-specific compounds ropivacaine and levobupivacaine, which provide similar efficacy to bupivacaine with a reduced risk of severe cardiotoxicity. Opioids are the other group of drugs widely used neuraxially, in particular to provide analgesia alone or more commonly in combination with other agents. The physicochemical properties of the various opioids explain the main differences in efficacy and safety between these drugs when used intrathecally, of which morphine, fentanyl and sufentanil are most commonly used. Another group of drugs including clonidine, dexmedetomidine and epinephrine (adrenaline) provide neuraxial analgesia via alpha-adrenergic receptors and are used mainly as adjuvants to local anaesthetics and opioids. Furthermore, intrathecal baclofen is in routine clinical use to treat spasticity in a number of neurological conditions. Beside these established approaches, a wide range of other drugs have been assessed for neuraxial administration to provide analgesia; however, most are in various early stages of investigation and are not used routinely. These drugs include neostigmine, ketamine, midazolam and adenosine, and the conotoxin ziconotide. The latter is possibly the most unusual compound here; it has recently gained registration for intrathecal use in specific chronic pain conditions.

An unusual presentation of a pituitary tumour in the early postpartum period

The case of a parturient, who first presented with a partial oculomotor nerve palsy shortly after caesarean delivery while participating in a clinical trial, is presented. The anaesthesia for the caesarean delivery involved a combined spinal-epidural with intrathecal bupivacaine and postoperative epidural pethidine patient-controlled analgesia. The trial was examining the possible effects of magnesium infusions on acute and chronic pain. The partial oculomotor nerve palsy was an unusual presentation and the signs and symptoms were transient. Magnetic resonance imaging confirmed the presence of a presumed pituitary macroadenoma. Possible reasons for the timing of onset and the rapid resolution of symptoms, and the implications and management of pituitary pathology in the peripartum period, are considered. The uncomplicated course of a later caesarean delivery in the same patient, using the same anaesthesia technique, is also noted.

Intraoperative nausea and vomiting during cesarean section under regional anesthesia

Nausea and vomiting during regional anesthesia for cesarean section are very common and unpleasant events. They cause significant distress to the patient and also interfere with the surgical procedure. They have multiple etiologies, which include hypotension, vagal hyperactivity, visceral pain, i.v. opioid supplementation, uterotonic agents and motion. The obstetric anesthesia literature has addressed these causative factors for nausea and vomiting individually, making it difficult for the anesthesiologists to have a comprehensive understanding of these important complications. This review highlights the anesthetic and non-anesthetic causes of intraoperative nausea and vomiting during regional anesthesia for cesarean section and the appropriate prophylactic and therapeutic management. Intraoperative nausea and vomiting can be best prevented by controlling hypotension, optimizing the use of neuraxial and i.v. opioids, improving the quality of block, minimizing surgical stimuli and judicious administration of uterotonic agents. Although prophylactic antiemetics have been advocated during cesarean sections, strict adherence to these practices can effectively lower the incidence of intraoperative nausea and vomiting without the requirement of antiemetic agents. Antiemetics, therefore, should be reserved for the prevention of intraoperative nausea and vomiting in high-risk patients and for the treatment of nausea and vomiting not responding to routine measures.

Continuous Intrathecal Meperidine for Severe Refractory Cancer Pain

The control of severe cancer pain may be problematic despite advances in pain management. Patients with severe intractable pain and/or intractable side effects may require aggressive interventional pain management strategies including the administration of medications by the continuous intrathecal route and/or neurosurgical procedures. Various medications, including opioids, local anesthetics, and alpha-2 agonists may be used intrathecally for the control of cancer pain. Failure of the intrathecal route may require the additional use of neurosurgical procedures such as cordotomy for pain control. We describe a case of severe cancer pain refractory to conventional intrathecal medications and cordotomy that was successfully managed by the addition of meperidine to the intrathecal regimen.

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.

Addition of meperidine to bupivacaine for spinal anaesthesia for Caesarean section

BACKGROUND

In a prospective, randomized, double-blind, placebo-controlled trial, we investigated the effect of adding meperidine 10 mg to intrathecal bupivacaine on the duration of early postoperative analgesia in 40 patients having elective Caesarean section under spinal anaesthesia.

METHODS

Patients received intrathecal injection of 0.5% hyperbaric bupivacaine 2.0 ml plus either normal saline 0.2 ml (saline group) or 5% meperidine 0.2 ml (meperidine group). After operation, all patients were given i.v. patient-controlled analgesia using morphine.

RESULTS

The duration of effective analgesia, defined as the time from intrathecal injection to first patient-controlled analgesia demand, was greater in the meperidine group (mean 234 min, 95% confidence interval 200-269 min) compared with the saline group (mean 125 min, 95% confidence interval 111-138 min; P<0.001). The 24 h morphine requirement was similar in the two groups. The meperidine group had a greater incidence of intraoperative nausea or vomiting compared with the saline group (11 vs 3; P=0.02).

CONCLUSION

Addition of meperidine 10 mg to intrathecal bupivacaine for Caesarean section is associated with prolonged postoperative analgesia but with greater intraoperative nausea and vomiting.

Adding low dose meperidine to spinal lidocaine prolongs postoperative analgesia

PURPOSE

To investigate the effects of the addition of low dose meperidine to spinal lidocaine on the sensory and motor blockade profile, and the quality and duration of postoperative analgesia.

METHODS

In a randomized double blind prospective dose finding study 40 patients undergoing transurethral prostatectomy with spinal anesthetic were allocated to receive 75 mg lidocaine 5% intrathecally as the sole agent (group A), or co-administered with 0.15 mg x kg(-1) meperidine (group B) or 0.30 mg x kg(-1) meperidine (group C). Sensory and motor blockade profiles were documented. Postoperatively, the amount of analgesics required, time to first analgesic, visual analogue scores and adverse events were recorded.

RESULTS

Sensory blocks at or above T10 was maintained for 128, 156 and 145 minutes in groups A, B and C respectively. There was no difference in the latency or duration of the motor block among the three groups. Patients in group C had lower visual analogue pain scores (VAPS) over time than did those in groups A and B (P < 0.05). Time to first analgesia was longer (429 +/- 197 minutes) in group C than in group A (254 +/- 157 minutes) (P < 0.05). Fewer patients in group C required parenteral opioid postoperatively than in group A (P < 0.05). The incidence of bradycardia was higher in the groups receiving meperidine. No symptoms of transient radicular irritation (TRI) were reported in the groups receiving meperidine.

CONCLUSION

The addition of 0.3 mg x kg(-1) of meperidine to spinal lidocaine prolongs postoperative analgesia without delaying discharge from post anesthetic care unit (Table II) and reduces the requirement for parenteral analgesics (Table III).