Adverse effects of extradural and intrathecal opiates: report of a nationwide survey in Sweden

Comparison of the Efficacies of Three Different Intrathecal Doses of Morphine in Achieving Postcesarean Delivery Analgesia

PURPOSE

The objective of this study is to compare the efficacies of 3 different intrathecal doses (80, 120, and 160 mcg) of morphine in achieving postcesarean delivery analgesia and the severity of the side effects thereof.

DESIGN

A prospective, randomized, double-blind study.

METHODS

A total of 150 pregnant women between the ages of 18 and 40, with a gestational week >36, who were planned to have elective cesarean section were included in the study. Patients were randomized into 3 groups based on the dosages of intrathecal doses of morphine (80, 120, and 160 mcg) they will receive in addition to 10 mg 0.5% hyperbaric bupivacaine and 20 mcg fentanyl. Intravenous (IV) patient-controlled analgesia (PCA) prepared with fentanyl was administered to each patient after the surgery. Postoperative 24-hour total IV PCA-fentanyl consumption was recorded. The patients were evaluated for side effects such as pain, nausea-vomiting, pruritus, sedation score, and respiratory depression after the surgery.

FINDINGS

PCA-fentanyl consumption was significantly higher in Group 1 compared to Group 2 and 3 (P = .047). There was no significant differences between the groups in terms of nausea-vomiting scores. The pruritus scores were significantly higher in Group 3 compared to Group 1 (P = .020). The pruritus scores were significantly higher in all groups at the postoperative 8th-hour (P = .013). Respiratory depression, which would require treatment, was not observed in any patient.

CONCLUSIONS

Based on the study findings, it was concluded that 120 mcg intrathecal morphine provides adequate analgesia with minimal side effects in cesarean sections.

Comparison of subcutaneous analgesic system and epidural analgesia for postoperative pain control in open pediatric oncology operations: A randomized controlled trial

PURPOSE

Children undergoing open oncologic surgery can have significant post-operative pain. The purpose of this trial was to compare a surgeon-placed subcutaneous analgesic system (SAS) to epidural analgesia.

METHODS

Single center randomized controlled trial including children ≤18 years undergoing open tumor resection between October 2018 and April 2021. Randomization to SAS or epidural was done preoperatively and perioperative pain management was standardized. Families were blinded to the modality. Comparisons of oral morphine equivalents (OME) and pain scores for three postoperative days, clinical outcome parameters, and parental satisfaction following unblinding were completed using non-parametric analyses.

RESULTS

Of 36 patients (SAS 18, Epidural 18), median age was 5 years (range <1-17). The Epidural cohort had less OME demand on postoperative day one (SAS 0.76 mg/kg, Epidural 0.11 mg/kg; p<0.01) and two (SAS 0.48 mg/kg, Epidural 0.07 mg/kg, p = 0.03). Pain scores were similar on postoperative days 1-3 (0-2 in both groups). The Epidural cohort had more device complications (SAS 11%, Epidural 50%; p = 0.03) and higher urinary catheter use (SAS 50%, Epidural 89%; p = 0.03). More than 80% of parents would use the same device in the future (SAS 100%, Epidural 84%, p = 0.23).

CONCLUSION

For children undergoing open oncologic abdominal or thoracic surgery, early post-operative pain control appears to be better with epidural analgesia; however, SAS has decreased incidence of device complications and urinary catheter use. Parental satisfaction is excellent with both modalities. SAS could be considered as an alternative to epidural, especially in settings when epidural placement is not available or contraindicated.

TYPE OF STUDY

Treatment study, Randomized controlled trial.

LEVEL OF EVIDENCE

Level 1.

Regional anaesthesia: what surgical procedures, what blocks and availability of a “block room”?

PURPOSE OF REVIEW

With an expected rise in day care procedures with enhanced recovery programs, the use of specific regional anaesthesia can be useful. In this review, we will provide insight in the used regional block and medication so far known and its applicability in a day care setting.

RECENT FINDINGS

Regional anaesthesia has been improved with the aid of ultrasound-guided placement. However, it is not commonly used in the outpatient setting. Old, short acting local anaesthetics have found a second life and may be especially beneficial in the ambulatory setting replacing more long-acting local anaesthetics such as bupivacaine.To improve efficiency, a dedicated block room may facilitate the performance of regional anaesthesia. However, cost-efficacy for improved operating time, patient care and hospital efficiency has to be established.

SUMMARY

Regional anaesthesia has proven to be beneficial in ambulatory setting. Several short acting local anaesthetics are favourable over bupivacaine in the day care surgery. And if available, there are reports of the benefit of an additional block room used in a parallel (monitored) care of patients.

Gadgeteering for Pain Relief: The 2021 John W. Severinghaus Lecture on Translational Science

In this first memorial lecture after John Severinghaus's death in 2021, the author traces his journey as a physician-scientist, using the framework of the hero's journey as described by the author Joseph Campbell 40 to 50 yr ago, and parallels that journey to his own. The author discusses how each were gadgeteers: Severinghaus in a creative engineering way, while the author's approach was asking simple questions translating basic research in pain from animals to humans. The classic hero's journey of departure to achieve a goal, then trials, transformation, and finally, returning with benefits to the individual and others is translated to the common physician-scientist career with motivations progressing from "I will show" to "I wonder if" to "I wonder why." Critical to this journey is self-questioning, openness to new ideas, and realizing that progress occurs through failure as much as success.

An Audit of Intrathecal Morphine Analgesia for Non-Obstetric Postsurgical Patients in an Adult Tertiary Hospital

We conducted a retrospective audit of adult non-obstetric patients who had received a single dose of intrathecal morphine for postoperative analgesia. These patients were predominantly admitted to a regular postsurgical ward with strict hourly nursing observations, treatment protocols in place and supervision by an Acute Pain Service for the first 24 hours after intrathecal morphine administration. A total of 409 cases were examined for sedation score, incidence of respiratory depression and other side-effects, admission to the high dependency or intensive care unit and opioidtolerance. Respiratory depression was defined as requiring treatment with naloxone (implying a sedation score of 3 irrespective of respiratory rate), or a sedation score of 2 with a respiratory rate less than six breaths per minute. The patients were predominantly elderly (57.2% were over the age of 70 years) and 84.8% had undergone vascular surgery. Of the total of 409 cases, only one case of respiratory depression was observed. A total of 77 patients were admitted to high dependency or intensive care unit for various reasons including management of postsurgical complications and patient co-morbidities. Our findings suggest that elderly patients who receive intrathecal morphine analgesia can be safely managed in a regular postsurgical ward.

Review article : The spinal administration of opioids in the treatment of acute and chronic pain: bolus doses, continuous infusion, intraventricular administration and implanted drug delivery systems

The spinal administration of opioids has been a significant addition to the previously available alternatives for pain control for patients with pain related to cancer. This article does not debate the more widespread use of these techniques in patients with nonmalignancy related pain. The incidence of destructive neurolytic procedures has fallen in most centres where spinal opioids have been administered. Some types of cancer pain have proved to be more effectively controlled than others, but in most circumstances potentially reversible procedures, such as outlined in this article, should be given a therapeutic trial before embarking on neuro-destructive procedures.1

It should be reemphasized however, that the spinal route of administration should be instituted only after systemically administered opioids have been shown to be ineffective or associated with intolerable side effects.

Pain Relief in the Intensive Care Unit

Treatment of severe pain in the intensive care unit first requires an assessment of pain type: nociceptive, cen tral, visceral, or referred. Narcotics given parenterally are the most commonly used agents for severe nocicep tive pain. Attention to potency, lipophilicity, route of administration, and side effects are all important. Cen tral nervous system pain may require nonnarcotic adju vants, anticonvulsants, or monoamine altering drugs for effective analgesia. The concomitance of emotional suf fering with the pain is an important problem to recog nize so that psychiatric disorders are properly treated.

A comparison between intrathecal clonidine and neostigmine as an adjuvant to bupivacaine in the subarachnoid block for elective abdominal hysterectomy operations: A prospective, double-blind and randomized controlled study

BACKGROUND AND AIMS

Adjuvant to the local anesthetic agent has proven benefits when used intrathecally. With regards to intrathecal bupivacaine as control, we have compared in this study the effects of clonidine and neostigmine when co-administered intrathecally with hyperbaric (0.5%) bupivacaine for abdominal hysterectomy.

MATERIALS AND METHODS

This prospective, randomized, double-blind study was conducted from May 2009 to June 2011. A total of 150 patients of American Society of Anaesthesiology grades I and II scheduled for abdominal hysterectomy under spinal anesthesia were randomly allocated into three groups. A volume of 3 ml of 0.5% hyperbaric bupivacaine was respectively added 1 ml solution containing 5% dextrose and 75 mcg of neostigmine in Group N, 1 ml containing 5% dextrose and 30 mcg of clonidine in Group C and 1 ml of 5% dextrose in Group D (control). We compared the sensory and motor block, the surgical condition, the duration of spinal analgesia and the side-effect profile.

RESULTS AND OBSERVATIONS

Sensory and motor blocks and duration of spinal analgesia were significantly increased in both Group C and Group N compared to Group D. More incidences of Nausea and vomiting were observed in Group N compared to other groups. The surgical condition was poorer in Group N compared to Group C.

CONCLUSION

Both intrathecal clonidine and neostigmine increase the bupivacaine-induced spinal block. However, clonidine provides better surgical condition and fewer incidences of nausea and vomiting.

Is a single low dose of intrathecal morphine a useful adjunct to patient-controlled analgesia for postoperative pain control following lumbar spine surgery? A preliminary report

BACKGROUND

Several studies addressing intrathecal morphine (ITM) use following spine surgery have been published either involving the pediatric population, using mid- to high-dose ITM, or not in conjunction with morphine patient-controlled analgesia (PCA).

OBJECTIVES

To determine whether low-dose ITM is a useful adjunct to PCA for postoperative pain control following elective lumbar spine surgery in adults.

METHODS

Thirty-two patients were enrolled in a double-blinded randomized controlled trial, and received either ITM or intrathecal placebo. Postoperatively, all patients were given a PCA pump and observed for the first 24 h in a step-down unit. Measurements of: total PCA morphine consumed in the first 24 h; intensity of pain; pruritus; nausea at 4 h, 8 h and 24&nbsp;h; time to first ambulation; length of hospital stay; and occurrences of respiratory depression were recorded.

RESULTS

The total PCA use was significantly lower in the ITM group. There were lower average pain scores in the ITM group, which increased to that of the intrathecal placebo group over 24 h; however, this failed to attain statistical significance. There were no differences in nausea, pruritus, time to first ambulation or hospital length stay. There were no cases of respiratory depression in either group.

CONCLUSIONS

ITM may be a useful adjunct to PCA, but did not decrease time to ambulation or length of stay.

Role of Clonidine as adjuvant to intrathecal bupivacaine in patients undergoing lower abdominal surgery: A randomized control study

Background:

Neuraxial anesthesia greatly expands the anesthesiologist armamentarium, providing alternatives to general anesthesia, especially in the lower abdominal surgeries. Clonidine, an alpha-2 adrenergic agonist, has a variety of actions, including potentiation of effects of local anesthetics. This study was undertaken to assess the degree of sensory and motor block and postoperative analgesia provided by low dose (50 mcg) intrathecal clonidine admixed with bupivacaine.

Aims:

The aim of this study is to establish efficacy and safety of intrathecal clonidine as adjuvant to bupivacaine.

Settings and Design:

The type of the study was double-blind randomized trial.

Materials and Methods:

Hundred patients were randomly allocated in two groups, A and B. Group A received bupivacaine 0.5%, 3 ml with placebo (normal saline 0.33 ml) and Group B, bupivacaine 0.5%, 3 ml with clonidine 50 μg (0.33 ml).

Statistical Analysis Used:

Statistical Package for Social Sciences version 15.0 statistical analysis software.

Results:

Mean duration of motor block was significantly higher in Group B (280.80 ± 66.88 min) as compared with Group A (183.60 ± 77.06 min). Significant difference in duration of sensory block was noted between Group B (295.20 ± 81.17 min) and Group A (190.80 ± 86.94 min). Duration of postoperative analgesia was significantly higher in Group B as compared to Group A (551.06 ± 133.64 min and 254.80 ± 84.19 min respectively). Mean visual analog scale scores at different time intervals were significantly lower in the study group (except for 4-h time interval), but the control group had better hemodynamic stability as compared with study group.

Conclusion:

The findings in this study suggested that use of clonidine 50 μg added to bupivacaine for spinal anesthesia effectively increased the duration of sensory block, duration of motor block, and duration of analgesia.

Comparison of epidural butorphanol and fentanyl as adjuvants in the lower abdominal surgery: A randomized clinical study

BACKGROUND

Epidural opioids acting through the spinal cord receptors improve the quality and duration of analgesia along with dose-sparing effect with the local anesthetics. The present study compared the efficacy and safety profile of epidurally administered butorphanol and fentanyl combined with bupivacaine (B).

MATERIALS AND METHODS

A total of 75 adult patients of either sex of American Society of Anesthesiologist physical status I and II, aged 20-60 years, undergoing lower abdominal under epidural anesthesia were enrolled into the study. Patients were randomly divided into three groups of 25 each: B, bupivacaine and butorphanol (BB) and bupivacaine + fentanyl (BF). B (0.5%) 20 ml was administered epidurally in all the three groups with the addition of 1 mg butorphanol in BB group and 100 μg fentanyl in the BF group. The hemodynamic parameters as well as various block characteristics including onset, completion, level and duration of sensory analgesia as well as onset, completion and regression of motor block were observed and compared. Adverse events and post-operative visual analgesia scale scores were also noted and compared. Data was analyzed using ANOVA with post-hoc significance, Chi-square test and Fisher's exact test. Value of P < 0.05 was considered significant and P < 0.001 as highly significant.

RESULTS

The demographic profile of patients was comparable in all the three groups. Onset and completion of sensory analgesia was earliest in BF group, followed by BB and B group. The duration of analgesia was significantly prolonged in BB group followed by BF as compared with group B. Addition of butorphanol and fentanyl to B had no effect on the time of onset, completion and regression of motor block. No serious cardio-respiratory side effects were observed in any group.

CONCLUSIONS

Butorphanol and fentanyl as epidural adjuvants are equally safe and provide comparable stable hemodynamics, early onset and establishment of sensory anesthesia. Butorphanol provides a significantly prolonged post-operative analgesia.

On-Q ® pain pump versus epidural for postoperative analgesia in children

PURPOSE

The On-Q(®) pain pump provides a continuous infusion of local anesthesia for management of postoperative pain. The objective of this study was to assess the efficacy and outcomes of the On-Q(®) pump compared to continuous epidural in children postoperatively.

METHODS

We performed a retrospective review of patients in our hospital who received a postoperative epidural or On-Q(®) pump from 2005 to 2008. Patients were sub-categorized by incision type.

RESULTS

Seventy patients received epidural and 66 On-Q(®). On-Q(®) therapy was longer by 1 day (p < 0.0001), but did not affect postoperative length of stay. Patients with On-Q(®) pumps had a decreased rate of Foley catheter placement (p = 0.002) and shorter duration of catheter use by more than a day (p < 0.001). Moderate to severe pain was similar in the two groups on postoperative days 0-5. Supplemental narcotic use was higher in the On-Q(®) group only on postoperative day 1 (p = 0.005) and in patients with midline and transverse abdominal incisions. No differences were seen in time to ambulation or recovery of postoperative ileus.

CONCLUSION

The On-Q(®) pain pump is an effective method for postoperative pain control, without the inherent risks of epidural catheters.

Comparison between intrathecal morphine with paravertebral patient controlled analgesia using bupivacaine for intraoperative and post-thoracotomy pain relief

Objectives:

This study was designed to compare the intrathecal morphine and paravertebral block with bupivacaine given before induction of anesthesia for intra-operative and post-thoracotomy pain relief for 48 hours using patient controlled paravertebral analgesia in post-operative period.

Methods:

After taken an approval from the ethics committee of the University, 40 patients were randomly assigned to receive either preservative-free intrathecal morphine 0.3 mg in 3 ml normal saline together with paravertebral block (group I) or paravertebral block alone using bupivacaine (group II) before an induction of anesthesia. No continuous infusion of bupivacaine was started in both groups. Primary outcomes were Visual Analogue Score (VAS) at rest and on coughing. Hemodynamic and respiratory effects, bupivacaine consumption, patient's satisfaction, and side effects like nausea, vomiting, urinary retention, and itching were considered as secondary outcomes. All patients in both groups received paracetamol 1 gram (gm) IV every 6 hourly for the 1^st 24 hr. Amount of rescue analgesic (pethidine 0.5 mg/kg IV) in both groups and total bupivacaine cumulative doses in 48 hrs were calculated.

Results:

VAS at rest and on coughing did not differ significantly between the 2 groups at 0, 1, 6, 12, 18, 24, and 48 hours (P= >0.1). At 24 hours, VAS increased in both the groups, but the increase in VAS was comparable in both groups. There were insignificant incidences of nausea, purities, and urinary retention in intrathecal group compared with paravertebral group. The other side effects and patient satisfaction did not show any statistical significant difference between 2 groups.

Conclusion:

Intrathecal morphine 0.3 mg is safe and effective way to improves pain control for thoracic surgery and was comparable to paravertebral patient control analgesia (PPCA) with bupivacaine for the 1^st 48 hours post-thoracotomy.

Aspiration pneumonitis caused by delayed respiratory depression following intrathecal morphine administration

Opioid analgesia is the primary pharmacologic intervention for managing pain. However, opioids can cause various adverse effects including pruritus, nausea, constipation, and sedation. Respiratory depression is the most fatal side effect. Therefore, cautious monitoring of respiratory status must be done after opioid administration. Here, we report a patient who suffered from respiratory depression with deep sedation and aspiration pneumonitis after intrathecal morphine administration.

Neuraxial morphine and respiratory depression: finding the right balance

Morphine is a drug commonly administered via the epidural or intrathecal route, and is regarded by many as the 'gold-standard' single-dose neuraxial opioid due to its postoperative analgesic efficacy and prolonged duration of action. However, respiratory depression is a recognized side effect of neuraxial morphine administered in the perioperative setting. We conducted an extensive review of articles published since 1945 that examine respiratory depression or failure associated with perioperative intrathecal or epidural morphine use. Respiratory depression was previously thought to result from the interaction of opioid in the cerebrospinal fluid with ventral medullary opioid receptors. More recently, the preBötzinger complex located in the medulla has been identified as the site responsible for the decrease in respiratory rate following systemic administration of opioids. Neurons in the preBötzinger complex expressing neurokinin-1 receptors are selectively inhibited by opioids, and therefore are the mediators of opioid-induced respiratory depression. Epidural, intrathecal and plasma pharmacokinetics of opioids are complex, vary between neuraxial compartments, and can even differ within the epidural space itself depending upon level of insertion. Caution should be exercised when prescribing systemic opioids (intravenous or oral) in addition to neuraxial morphine as this can compound the potential for early or delayed respiratory depression. There is a wide range of incidences for respiratory depression following neuraxial morphine in a perioperative setting. Disparity of definitions used for the diagnosis of respiratory depression in the literature precludes identification of the exact incidence of this rare event. The optimal neuraxial opioid dose is a balance between the conflicting demands of providing optimal analgesia while minimizing dose-related adverse effects. Dose-response studies show that neuraxial morphine appears to have an analgesic efficacy 'ceiling'. The optimal 'single-shot' intrathecal dose appears to be 0.075-0.15 mg and the ideal 'single-shot' epidural morphine dose is 2.5-3.75 mg. Analgesic efficacy studies have not been adequately powered to show differences in the incidence of clinically significant respiratory depression. Opioid antagonists such as naloxone to prevent or treat opioid-induced respiratory depression have a number of limitations. Researchers have recently focused on non-opioid drugs such as serotonin receptor agonists. Early evidence suggests that ampakine (α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid [AMPA]) receptor modulators may be effective at reducing opioid-induced respiratory depression while maintaining analgesia. Sodium/proton exchanger type 3 (NHE3) inhibitors, which act centrally on respiratory pathways, also warrant further study.

Retrospective analysis of high-dose intrathecal morphine for analgesia after pelvic surgery

BACKGROUND

The effectiveness of intrathecal opioids (ITOs) for postoperative analgesia has been limited by reduced opioid dosing because of opioid-related side effects, most importantly respiratory depression. To overcome these limitations, high-dose intrathecal morphine was combined with a continuous intravenous (IV) postoperative naloxone infusion. The aim of the present chart analysis was to investigate the safety and efficacy of high-dose ITOs combined with IV naloxone compared with IV opioid analgesia alone.

METHODS

A retrospective chart analysis was performed on 121 female patients requiring major pelvic surgery. Ninety-eight patients received a single injection of high-dose ITOs before administration of typical general anesthesia, followed by an IV naloxone infusion at 5 µg⁄kg⁄h started post-ITO and continued for 22 h postoperatively. Twenty-three patients were given IV morphine (IVM) for postoperative analgesia and served as a reference group. Postoperative pain relief, analgesic consumption and ability to ambulate were assessed for 48 h postoperatively. Treatment safety was assessed by monitoring opioid-related side effects and vital signs. Data are presented as mean ± SD.

RESULTS

Mean ITOs given were morphine 1.1±0.2 mg combined with fentanyl 49 ± 6 µg. The mean worst pain visual analogue scale score in the first 12 h postoperatively was 0.2 ± 0.90 in the ITO group versus 4.3 ± 3.0 in the IVM group (P<0.05). On postoperative day 2, the mean worst pain visual analogue scale score was only 1 ± 1.8 in the ITO group versus 4.1 ± 2.6 in the IVM group (P<0.05). Analgesic requirements were reduced in the ITO group. In the first 24 h, the ITO group used 6.8±10.2 morphine equivalents (mg IV) versus 76.1 ± 44.4 in the IVM group (P<0.05). All patients in the ITO group were able to ambulate in the first 12 h postoperatively compared with 17⁄23 in the IVM group. There was a higher incidence of opioid-related sedation in the IVM group. Other opioid-related side effects were infrequent and minor in both groups.

CONCLUSIONS

High-dose ITOs combined with a postoperative IV naloxone infusion provided excellent analgesia for major pelvic surgery. The IV naloxone infusion combined with high-dose ITOs appeared to control opioid side effects without affecting analgesia.

Comparison of spinal anesthesia with general anesthesia on morphine requirement after abdominal hysterectomy

PURPOSE

The aim of this study was to compare morphine consumption with patient-controlled analgesia (PCA) between spinal anesthesia (SA) (bupivacaine, morphine and fentanyl) and general anesthesia (GA) (sufentanil) after an abdominal hysterectomy.

METHODS

Forty women were randomly assigned to receive SA with bupivacaine 15 mg, 0.15 mg of intrathecal morphine and 15 microg of fentanyl or GA with sufentanil, both combined with PCA. The primary outcome was morphine consumption with the PCA device. The secondary outcomes were post-operative pain at rest and under stress on a visual analog scale, nausea, pruritus and respiratory depression on a standardized scale. Outcome measures were recorded at 6, 12, 18, 24 and 48 h post-anesthesia. The duration of post-anesthesia care unit (PACU) and hospital stay were recorded.

RESULTS

Patients in the SA group consumed at least two times less morphine at each time interval than the GA group: at 48 h, they used 19 +/- 17 vs. 81 +/- 31 mg (P<0.0001). Post-operative pain at rest was lower in the SA group until the 18th hour and under stress until the 48th. There was more sedation in the GA group until the 18th hour. Little difference was observed in the incidence of pruritus. Nausea was more intense at the 6th hour in the GA group. There was no difference in the respiratory rate. The duration of PACU stay was shorter for the SA group (52 +/- 9 vs. 73 +/- 11 min, P<0.0001) as was the duration of hospital stay (2.2 +/- 0.4 vs. 3.3 +/- 0.7 days, P=0.01).

CONCLUSIONS

It is concluded that intrathecal morphine 0.15 mg with 15 microg of fentanyl decreases post-operative pain and morphine consumption by PCA without increasing adverse reactions for women undergoing an abdominal hysterectomy.

Post-operative pain management using patient-controlled analgesia

Patient-controlled analgesia is an effective form of postoperative pain management for select lower extremity orthopedic procedures in the in-patient setting. The goal of this article is to present an introduction to the prescription and management of patient-controlled analgesia in the acute, postoperative setting. The surgeon should have a thorough understanding of this intervention as it relates to pain control and overall patient care.

The safety of concurrent administration of opioids via epidural and intravenous routes for postoperative pain in pediatric oncology patients

Supplementation of epidural opioid analgesia with intravenous opioids is usually avoided because of concern about respiratory depression. However, the choice of adjunct analgesic agents for pediatric oncology patients is limited. Antipyretic drugs may mask fever in neutropenic patients, and nonsteroidal anti-inflammatory agents may exert antiplatelet effects and interact with chemotherapeutic agents. We examined the safety of concurrent use of epidural and intravenous opioids in a consecutive series of 117 epidural infusions in pediatric patients and compared our findings to those reported by other investigators. We observed a 0.85% rate of clinically significant respiratory complications. The single adverse event was associated with an error in dosage. In our experience, the supplementation of epidural opioid analgesia with intravenous opioids has been a safe method of postoperative pain control for pediatric patients with cancer.

Effects of rat/mouse hemokinin-1, a mammalian tachykinin peptide, on the antinociceptive activity of pethidine administered at the peripheral and supraspinal level

We have recently reported that rat/mouse hemokinin-1 (r/m HK-1), a mammalian tachykinin, produced dose- and time-related antinociceptive effects at the supraspinal level via activating NK(1) receptors. Moreover, r/m HK-1 remarkably enhanced both the antinociceptive extent and duration of morphine administered at the peripheral and supraspinal level through a convergence of pharmacological effects of opioid-responsive neurons. Pethidine hydrochloride is an important narcotic analgesic, which acts as an opiate agonist and has pharmacological effects similar to morphine. To improve our knowledge of the pharmacology of pethidine, the aim of the present study was to investigate the relationship between the nociception of r/m HK and pethidine by comparing it with that of r/m HK-1 and morphine. Our data showed that r/m HK-1 remarkably enhanced the antinociceptive extent of pethidine administered at the peripheral level, but not at the supraspinal level. These antinociceptive effects were blocked by prior treatment with the classical opioid receptor antagonist naloxone, indicating that the potentiated analgesic effect is mediated by opioid-responsive neurons. Differences in the antinociceptive activity of pethidine and morphine in combination with r/m HK-1, arise because there are differences in the physicochemical and pharmacokinetic properties of pethidine and morphine, particularly their lipophilicity. Our results may pave the way for a new strategy for the control of pain and may provide a clinical strategy to enable selection of either opioid as a priority.

Pharmacokinetic-pharmacodynamic modeling of the effectiveness and safety of buprenorphine and fentanyl in rats

Objective

Respiratory depression is a serious and potentially life-threatening side-effect of opioid therapy. The objective of this investigation was to characterize the relationship between buprenorphine or fentanyl exposure and the effectiveness and safety outcome in rats.

Methods

Data on the time course of the antinociceptive and respiratory depressant effect were analyzed on the basis of population logistic regression PK–PD models using non-linear mixed effects modeling software (NONMEM). The pharmacokinetics of buprenorphine and fentanyl were described by a three- and two-compartment model, respectively. A logistic regression model (linear logit model) was used to characterize the relationship between drug exposure and the binary effectiveness and safety outcome.

Results

For buprenorphine, the odds ratios (OR) were 28.5 (95% CI, 6.9–50.1) and 2.10 (95% CI, 0.71–3.49) for the antinociceptive and respiratory depressant effect, respectively. For fentanyl these odds ratios were 3.03 (95% CI, 1.87–4.21) and 2.54 (95% CI, 1.26–3.82), respectively.

Conclusion

The calculated safety index (OR_{antinociception}/OR_{respiratory depression}) for fentanyl of 1.20 suggests that fentanyl has a low safety margin, implicating that fentanyl needs to be titrated with caution. For buprenorphine the safety index is 13.54 suggesting that buprenorphine is a relatively safe opioid.

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.

Patient-controlled analgesia

One of the most common methods for providing postoperative analgesia is via patient-controlled analgesia (PCA). Although the typical approach is to administer opioids via a programmable infusion pump, other drugs and other modes of administration are available. This article reviews the history and practice of many aspects of PCA and provides extensive guidelines for the practice of PCA-administered opioids. In addition, potential adverse effects and recommendations for their monitoring and treatment are reviewed.

Evolving spinal analgesia practice in palliative care

Intraspinal analgesia can be helpful in some patients with intractable pain. Over 15 years palliative care professionals evolved their spinals policy through a repeated series of evaluations, discussions and literature reviews. One hundred intraspinal lines were then reviewed. Notable changes in policy were the switch from epidurals to intrathecals, and the insertion of lines during working hours rather than as emergencies. Our efficacy, and frequency of adverse effects, is equal or better to published studies. Key issues in reducing adverse effects were the improved care of the spinal line exit site, a change from bolus administration to continuous infusions, and modifying line insertion techniques. Current policy is to use continuous infusions of diamorphine and bupivacaine in a 1:5 ratio through externalized intrathecal lines. The lines are effective in approximately two thirds of patients and can be kept in place for up to 18 months. The policy continues to be updated and common documentation is now in place.

Epidural oxycodone or morphine following gynaecological surgery †

BACKGROUND

The analgesic action of oxycodone is of rapid onset, in contrast to morphine, and is mediated by kappa-opioid receptors of the spinal cord. We compared analgesia and side-effects of epidural oxycodone with those of morphine after gynaecological surgery.

METHODS

We studied prospectively in 75 women in a double-blind, randomized manner: epidural morphine 6 mg day(-1) (n=25), epidural oxycodone 6 mg day(-1) (n=25) and epidural oxycodone 12 mg day(-1) (n=25). All patients underwent gynaecological surgery under general (isoflurane and nitrous oxide) and epidural anaesthesia. Visual analogue scale (VAS) pain scores at rest and on coughing, verbal descriptive scale (VDS) satisfaction scores, sedation scores, pruritus scores and nausea/vomiting scores were recorded for 3 days after surgery.

RESULTS

VAS pain scores at rest in patients who received oxycodone 6 mg day(-1) were higher than in patients who received morphine 6 mg day(-1) at 6 h and on the first postoperative day and were significantly higher than in patients who received oxycodone 12 mg day(-1) on the first postoperative day. Scores for nausea, vomiting and pruritus in patients who received oxycodone 6 mg day(-1) and 12 mg day(-1) were lower than those in patients who received morphine. No significant differences were seen in VAS at cough and VDS satisfaction scores between the three groups.

CONCLUSION

Epidural oxycodone was as effective as morphine at the doses investigated, with fewer side-effects.

Respiratory and haemodynamic effects of acute postoperative pain management: evidence from published data

BACKGROUND

This study examines the evidence from published data concerning the adverse respiratory and haemodynamic effects of three analgesic techniques after major surgery; i.m. analgesia, patient-controlled analgesia (PCA), and epidural analgesia.

METHODS

A MEDLINE search of the literature was conducted for publications concerned with the management of postoperative pain. Information relating to variables indicative of respiratory depression and of hypotension was extracted from these studies. Over 800 original papers and reviews were identified. Of these papers, 212 fulfilled the inclusion criteria but only 165 provided usable data on adverse effects. Pooled data obtained from these studies, which represent the experience of a total of nearly 20,000 patients, form the basis of this study.

RESULTS

There was considerable variability between studies in the criteria used for defining respiratory depression and hypotension. The overall mean (95% CI) incidence of respiratory depression of the three analgesic techniques was: 0.3 (0.1-1.3)% using requirement for naloxone as an indicator; 1.1 (0.7-1.7)% using hypoventilation as an indicator; 3.3 (1.4-7.6)% using hypercarbia as an indicator; and 17.0 (10.2-26.9)% using oxygen desaturation as an indicator. For i.m. analgesia, the mean (95% CI) reported incidence of respiratory depression varied between 0.8 (0.2-2.5) and 37.0 (22.6-45.9)% using hypoventilation and oxygen desaturation, respectively, as indicators. For PCA, the mean (95% CI) reported incidence of respiratory depression varied between 1.2 (0.7-1.9) and 11.5 (5.6-22.0)%, using hypoventilation and oxygen desaturation, respectively, as indicators. For epidural analgesia, the mean (95% CI) reported incidence of respiratory depression varied between 1.1 (0.6-1.9) and 15.1 (5.6-34.8)%, using hypoventilation and oxygen desaturation, respectively, as indicators. The mean (95% CI) reported incidence of hypotension for i.m. analgesia was 3.8 (1.9-7.5)%, for PCA 0.4 (0.1-1.9)%, and for epidural analgesia 5.6 (3.0-10.2)%. Whereas the incidence of respiratory depression decreased over the period 1980-99, the incidence of hypotension did not.

CONCLUSIONS

Assuming a mixture of analgesic techniques, Acute Pain Services should expect an incidence of respiratory depression, as defined by a low ventilatory frequency, of less than 1%, and an incidence of hypotension related to analgesic technique of less than 5%.

Local anaesthetics and additives for spinal anaesthesia--characteristics and factors influencing the spread and duration of the block

Different characteristics of patients and local anaesthetic formulations will influence the spread of spinal anaesthesia. The predictability of the spread of spinal anaesthesia can be improved by altering both baricity of the solution, and the position of the patient during the intrathecal local anaesthetic injection. The role of adrenaline and clonidine in prolonging the block and associated side effects is discussed. The role of opioids added to local anaesthetic solutions is discussed from a cost/benefit point of view.

A history of neuraxial administration of local analgesics and opioids

The history of intrathecal and epidural anaesthesia is in parallel with the development of general anaesthesia. As ether anaesthesia (1846) is considered the first modern anaesthetic since its use by Morton 157 yr ago, so Bier made history by using cocaine for intrathecal anaesthesia in 1898. The first published report on opioids for intrathecal anaesthesia belongs to a Romanian surgeon, Racoviceanu-Pitesti, who presented his experience at Paris in 1901. It was almost a century before the opioids were used for epidural analgesia. Behar and his colleagues published the first report on the epidural use of morphine for the treatment of pain in The Lancet in 1979. Epidural and intrathecal opioids are today part of a routine regimen for intra- and postoperative analgesia. Over the last 30 yr, the use of epidural opioids has became a standard for analgesia in labour and delivery, and for the management of chronic pain. Finally, epidural opioids have been shown to have a pre-emptive effect, when used before major surgery. We present the evolution of neuraxial anaesthesia and the history of intrathecal and epidural administration of opioids.

Regional Anaesthesia in the Elderly

The number of elderly patients presenting for anaesthesia and surgery has increased exponentially in recent years. Regional anaesthesia is frequently used in elderly patients undergoing surgery. Although the type of anaesthesia (general versus regional anaesthesia) has no substantial effect on perioperative morbidity and mortality in any age group; it intuitively makes sense that elderly patients would benefit from regional anaesthesia because they remain minimally sedated throughout the procedures and awaken with excellent postoperative pain control. However, a multitude of factors influence the outcome, such as the type, duration and invasiveness of the operation, co-existing medical and mental status of the patient and the skill and expertise of the anaesthesiologist and surgeon. These factors make it difficult to decide if and when one technique is equivocally better than another. Thus, it is more important to optimise the overall management of the patient during the perioperative period and, in most cases, it is the quality of the anaesthetic administered rather than the type of anaesthetic which is most important. Sedatives used for regional anaesthesia in the elderly should be short acting, easy to administer, have a low adverse effect profile and high safety margin. Midazolam, lorazepam, ketamine, propofol and low-dose opioids have been successfully used for sedation in the elderly. Aging affects the pharmacokinetics and pharmacodynamics of local anaesthetics, composition and characteristics of tissues and organs within the body, and physiological functions of the body. Changes in the systematic absorption, distribution and clearance of local anaesthetics lead to an increased sensitivity, decreased dose requirement and a change in the onset and duration of action in the elderly. Decreases in neural population, neural conduction velocity and inter-Schwann cell distance can lead to an increased sensitivity to local anaesthetics in the elderly. The addition of an opioid and epinephrine (adrenaline) has been shown to be useful in central neuraxial blockade. Epinephrine also can prolong the duration of peripheral nerve blocks. However, caution must be exercised as epinephrine has the potential for causing ischaemic neurotoxicity in peripheral nerves. Regional anaesthesia appears to be safe and beneficial in elderly patients; however, every anaesthetic administered must be assessed on a case-by-case basis and particular consideration should be given to the health status of the patient, the operation being performed and the expertise of the anaesthesiologist.

A history of neuraxial administration of local analgesics and opioids

The history of intrathecal and epidural anaesthesia is in parallel with the development of general anaesthesia. As ether anaesthesia (1846) is considered the first modern anaesthetic since its use by Morton 157 yr ago, so Bier made history by using cocaine for intrathecal anaesthesia in 1898. The first published report on opioids for intrathecal anaesthesia belongs to a Romanian surgeon, Racoviceanu-Pitesti, who presented his experience at Paris in 1901. It was almost a century before the opioids were used for epidural analgesia. Behar and his colleagues published the first report on the epidural use of morphine for the treatment of pain in The Lancet in 1979. Epidural and intrathecal opioids are today part of a routine regimen for intra- and postoperative analgesia. Over the last 30 yr, the use of epidural opioids has became a standard for analgesia in labour and delivery, and for the management of chronic pain. Finally, epidural opioids have been shown to have a pre-emptive effect, when used before major surgery. We present the evolution of neuraxial anaesthesia and the history of intrathecal and epidural administration of opioids.

Definitions of "respiratory depression" with intrathecal morphine postoperative analgesia: a review of the literature

PURPOSE

To review the postoperative intrathecal morphine (ITM) analgesia literature for their definitions of "respiratory depression" (RD).

SOURCE

Medline (1966 - June Week 5 2001) and reference lists were searched for original studies involving bolus-dose ITM for postoperative analgesia, which used "respiratory depression" or similar terms.

PRINCIPLE FINDINGS

The search identified 209 studies. These were included if ITM use was appropriate (bolus dose, postoperative analgesia) and the term "respiratory depression" was used, which left 96 studies remaining. Forty-four (46%) did not define "RD" despite using this term. A further 24 (25%) defined RD with respiratory rate (RR) alone. Only 28 (29%) defined RD with more than RR alone. There was no statistically significant association between the presence of a definition for RD with study design, study size or publication period. Also, no significant association existed between rigorousness of RD definitions and the above factors.

CONCLUSION

The term "respiratory depression" has no clear definition from a review of the literature on ITM use for postoperative analgesia. While defining RD with bradypnea is superior to having no definition, this is still inadequate. In future research, the consistent use of terms with specific meanings will facilitate understanding the true incidence of ITM's respiratory effects. If "respiratory depression" is used, then an explicit definition of its meaning should be provided. Future research must also address what is clinically significant respiratory impairment from intrathecal opioids, and how to optimally monitor for this. Further delineating their risks vs benefits will allow for more optimal dosing.

Acute pain management for patients undergoing thoracotomy

Management of thoracotomy pain can be difficult, but the benefits of effective pain control are significant. A variety of modalities for treating postoperative pain after thoracotomy are available, including systemic opiates, regional analgesics, and new oral and parenteral agents. This work provides a review of the literature and recommendations for the clinician.

Pain relief and safety after major surgery. A prospective study of epidural and intravenous analgesia in 2696 patients

BACKGROUND

Adverse effects may still limit the use of continuous epidural and intravenous analgesia in surgical wards. This study postulated that postoperative epidural analgesia was more efficient, and had fewer side-effects than intravenous morphine. The aim was to investigate efficacy, adverse effects and safety of the treatments in a large patient population.

METHODS

During a five-year period 2696 patients undergoing major surgery, received either epidural or intravenous analgesia for postoperative pain relief. The patients were prospectively monitored in surgical wards. Pain was evaluated with a numeric rating scale (0-10) at rest/mobilization. Treatment duration, respiratory depression, sedation/hallucinations/nightmares/confusion, nausea/vomiting, pruritus, orthostatism/leg weakness, and insufficient pain relief were registered. Pain relief for all patients aimed at a pain scoring of less than 4 at rest.

RESULTS

Epidural analgesia was used in 1670 patients, and intravenous morphine in 1026 patients. Patients with epidural analgesia experienced less pain both at rest and during mobilization. Insufficient treatment effects such as dose adjustments, orthostatism/leg weakness, and pruritus were more common in the epidural group. Respiratory depression and sedation/hallucinations/nightmares/confusion occurred more often in the intravenous group. Thoracic epidural catheters caused a lower incidence of motor blockade compared to lumbar catheter placements.

CONCLUSION

In a large patient population the use of epidural and intravenous postoperative analgesia was considered safe in surgical wards, and the incidence of adverse effects was low. Patients with epidural analgesia experienced overall less pain, while opioid related side-effects were more common with intravenous morphine analgesia.

Can single dose preoperative intrathecal morphine sulfate provide cost-effective postoperative analgesia and patient satisfaction during radical prostatectomy in the current era of cost containment?

We retrospectively analyzed the analgesic efficacy and surgical outcomes of a single preoperative intrathecal long-acting morphine sulfate injection (0.25-0.5 mg) and postoperative intravenous (i.v.) ketorolac in 62 patients who underwent radical retropubic prostatectomy (RRP). Total postoperative analgesic requirement was documented along with assessment of length of hospital stay, pain control and time for resumption of normal activity. Postoperatively, 45% of patients required only nonsteroidal agents (ketorolac), whereas 55% needed a mean of 13.3 mg of supplemental i.v. morphine sulfate. Mean hospital stay was 2.3+/-0.3 days. Eighty-two per cent of patients felt the length of hospital stay adequate. Ninety-seven per cent of patients were satisfied with anesthesia selected and 95% of patients considered pain control on postoperative days 1 and 2 as effective. All patients resumed to full physical activity by 5.3+/-0.4 weeks after surgery. We conclude that a single preoperative injection of intrathecal morphine sulfate combined with i.v. ketorolac postoperatively results in effective analgesia, diminished supplemental narcotic requirement and high patient satisfaction during radical retropubic prostatectomy.

Comparative provocation test of respiratory monitoring methods

OBJECTIVE

The aim of this study was to compare clinically relevant performance of: 1) a prototype respiratory sensor based on capnometry with two alternative signal receptor fixations, 2) a fiberoptic humidity sensor and 3) human visual observation. Comparative provocation tests were performed on volunteers at the Post-Anesthesia Care Unit at Västerås Central Hospital.

METHODS

The experimental tests involved 10 healthy, voluntary test subjects, instructed to intersperse normal breathing with protocol provocations of breath holding, limb and head movements, and nasal oxygen supplement. The signal outputs from the three respiratory monitoring methods were recorded on a personal computer. The signal analysis included visual categorising of the signals and counting breath events. Recognising that none of the methods could act as reference, events were classified as "unanimous," "majority" or "minority" events depending on how many of the three methods that detected a breath.

RESULTS

The average total recording time was 37 minutes per subject. The respiratory rates varied from 6.5 to 19 breaths per minute, with a mean value of 11.4 breaths/minute. The breath hold duration ranged from 18 to 50 seconds. Discrepancies between the three methods were found in more than 20% of the marked events. The most frequent majority events were due to events not recorded by the observer who, on the other hand, contributed the least to minority events. The provocations made by the subjects during the measurement did not increase the rates of majority and minority events, compared to periods of no provocation. The fiberoptic device exhibited a larger count of minority events but a smaller contribution to majority events than the capnometry prototype.

CONCLUSIONS

The capnometry and fiberoptic sensors exhibit differences in responses that may be understood from basic principles. The importance of the physical application of the sensor to the patient was clearly observed. The optimum design remains to be found.

Regional analgesia in the intensive care unit. Principles and practice

Nociception is a complicated process, and only in recent years have the neural pathways and mediators of pain transmission been unraveled. Several regional anesthetic interventions, most notably epidural drug delivery, can interrupt nociception and provide safe and effective pain control in critically ill patients while substantially reducing the need for systemic medications. This article discusses the possibilities for regional control of the neurobiology of nociception and describes the arsenal of regional anesthetic techniques available to the intensivist. Used wisely, regional techniques can provide excellent pain control and may have a significant role in improving overall patient outcome. Regional analgesia offers the best opportunity to provide substantial analgesia without significant central opioid effects. Well-conducted regional analgesia can reduce many of the unpleasant or potentially problematic side effects observed when traditional intravenous medications are used exclusively for pain control.

Respiratory failure due to the combined effects of transdermal fentanyl and epidural bupivacaine/diamorphine following radical nephrectomy

The transdermal therapeutic system (TTS) fentanyl has been designed for rate-controlled drug delivery. When the system is applied, a fentanyl depot concentrates in the upper skin layers. Plasma concentrations are not measurable until 2 hours after application, and it takes an 8-16 hr latency period until full clinical fentany effects are observed. Following removal, serum fentanyl concentrations decline gradually and fall to about 50% in approximately 16 hours. We report the case of a 77-year-old man with a history of severe arthritis, who was receiving transdermal fentanyl and developed respiratory failure after starting epidural diamorphine/bupivacaine for postoperative pain relief following radical nephrectomy.

Onset and offset of intrathecal morphine versus nalbuphine for postoperative pain relief after total hip replacement

BACKGROUND

We designed this study to compare the postoperative analgesic effects of intrathecal morphine and nalbuphine, the endpoints being onset and offset of action.

METHODS

Geriatric patients scheduled for elective total hip replacement under continuous spinal anaesthesia were randomized to two double-blinded groups in the recovery room as soon as they experienced a pain score higher than 3 cm on the visual analogue scale (VAS, 0-10 cm). Either 160 microg morphine or 400 microg nalbuphine in 4 ml normal saline were administered intrathecally. Pain scores on VAS, rescue analgesia (diclofenac and morphine, not allowed during the first 60 min), and the adverse effects (respiratory depression, postoperative nausea and vomiting, itching) were recorded for 24 h after surgery.

RESULTS

The study was stopped after inclusion of 2 x 12 patients due to slow onset of analgesia in the morphine patients. In the nalbuphine group, when compared to the morphine group, the time to a pain score <3 cm (8+/-6 vs. 31+/-32 min, P<0.001), the time to the lowest pain score (18+/-11 vs. 66+/-75 min, P<0.001) and the time to the first systemic analgesic intervention for a pain score >3 cm (218+/-256 vs. 1076+/-440 min, P<0.05) were significantly shorter. The analgesic requirements during the first 24 h were significantly lower in the morphine group (P<0.001).

CONCLUSION

We conclude that after total hip replacement, administration of intrathecal nalbuphine resulted in a significantly faster onset of pain relief and shorter duration of analgesia than intrathecal morphine.