Dose-response pharmacology of intrathecal morphine in human volunteers

Analgesic Efficacy and Safety of Intrathecal Morphine or Intercostal Levobupivacaine in Lung Cancer Patients after Major Lung Resection Surgery by Videothoracoscopy: A Prospective Randomized Controlled Trial

Background: Lung resection using video-assisted thoracoscopic surgery (VATS) improves surgical accuracy and postoperative recovery. Unfortunately, moderate-to-severe acute postoperative pain is still inherent to the procedure, and a technique of choice has not been established for the appropriate control of pain. In this study, we aimed to compare the efficacy and safety of intrathecal morphine (ITM) with that of intercostal levobupivacaine (ICL). Methods: We conducted a single-center, prospective, randomized, observer-blinded, controlled trial among 181 adult patients undergoing VATS (ISRCTN12771155). Participants were randomized to receive ITM or ICL. Primary outcomes were the intensity of pain, assessed by a numeric rating scale (NRS) over the first 48 h after surgery, and the amount of intravenous morphine used. Secondary outcomes included the incidence of adverse effects, length of hospital stay, mortality, and chronic post-surgical pain at 6 and 12 months after surgery. Results: There are no statistically significant differences between ITM and ICL groups in pain intensity and evolution at rest. In cough-related pain, differences in pain trajectories over time are observed. Upon admission to the PACU, cough-related pain was higher in the ITM group, but the trend reversed after 6 h. There are no significant differences in adverse effects. The rate of chronic pain was low and did not differ significantly between groups. Conclusions: ITM can be considered an adequate and satisfactory regional technique for the control of acute postoperative pain in VATS, compatible with the multimodal rehabilitation and early discharge protocols used in these types of surgeries.

Robot-assisted laparoscopic nephrectomy: early outcome measures with the implementation of multimodal analgesia and intrathecal morphine via the acute pain service

PURPOSE

The objective of this study was to perform a retrospective cohort analysis, in which we measured the association of an acute pain service (APS)-driven multimodal analgesia protocol that included preoperative intrathecal morphine (ITM) compared to historic controls (i.e., surgeon-driven analgesia protocol without ITM) with postoperative opioid use.

METHODS

This was a retrospective cohort study in which the primary objective was to determine whether there was a decrease in median 24-h opioid consumption (intravenous morphine equivalents [MEQ]) among robotic nephrectomy patients whose pain was managed by the surgical team prior to the APS, versus pain managed by APS. Secondary outcomes included opioid consumption during the 24-48 h and 48-72 h period and hospital length of stay. To create matched cohorts, we performed 1:1 (APS:non-APS) propensity score matching. Due to the cohorts occurring at the different time periods, we performed a segmented regression analysis of an interrupted time series.

RESULTS

There were 76 patients in the propensity-matched cohorts, in which 38 (50.0%) were in the APS cohort. The median difference in 24-h opioid consumption in the pre-APS versus APS cohort was 23.0 mg [95% CI 15.0, 31.0] (p < 0.0001), in favor of APS. There were no differences in the secondary outcomes. On segmented regression, there was a statistically significant drop in 24-h opioid consumption in the APS cohort versus pre-APS cohort (p = 0.005).

CONCLUSIONS

The implementation of an APS-driven multimodal analgesia protocol with ITM demonstrated a beneficial association with postoperative 24-h opioid consumption following robot-assisted nephrectomy.

Kappa opioids inhibit the GABA/glycine terminals of rostral ventromedial medulla projections in the superficial dorsal horn of the spinal cord

Descending projections from neurons in the rostral ventromedial medulla (RVM) make synapses within the superficial dorsal horn (SDH) of the spinal cord that are involved in the modulation of nociception, the development of chronic pain and itch, and an important analgesic target for opioids. This projection is primarily inhibitory, but the relative contribution of GABAergic and glycinergic transmission is unknown and there is limited knowledge about the SDH neurons targeted. Additionally, the details of how spinal opioids mediate analgesia remain unclear, and no study has investigated the opioid modulation of this synapse. We address this using ex vivo optogenetic stimulation of RVM fibres in conjunction with whole-cell patch-clamp recordings from the SDH in spinal cord slices. We demonstrate that both GABAergic and glycinergic neurotransmission is employed and show that SDH target neurons have diverse morphological and electrical properties, consistent with both inhibitory and excitatory interneurons. Then, we describe a subtype of SDH neurons that have a glycine-dominant input, indicating that the quality of descending inhibition across cells is not uniform. Finally, we discovered that the kappa-opioid receptor agonist U69593 presynaptically suppressed most RVM-SDH synapses. By contrast, the mu-opioid receptor agonist DAMGO acted both pre- and post-synaptically at a subset of synapses, and the delta-opioid receptor agonist deltorphin II had little effect. These data provide important mechanistic information about a descending control pathway that regulates spinal circuits. This information is necessary to understand how sensory inputs are shaped and develop more reliable and effective alternatives to current opioid analgesics. Abstract figure legend We combined ex vivo optogenetic stimulation of RVM fibres with whole cell electrophysiology of SDH neurons to investigate the final synapse in a key descending pain modulatory pathway. We demonstrate that both glycine and GABA mediate signalling at the RVM-SDH synapse, that the SDH targets of RVM projections have diverse electrical and morphological characteristics, and that presynaptic inhibition is directly and consistently achieved by kappa opioid agonists. Opioid receptors shown are sized relative to the proportion of neurons that responded to its specific agonists (81 and 84percent of DF and non-DF neurons responded to kappa opioid receptor agonists, respectively. Responses that occurred in <255 percentage of neurons are not indicated here). This article is protected by copyright. All rights reserved.

The use of intrathecal morphine for acute postoperative pain in lower limb arthroplasty surgery: a survey of practice at an academic hospital

BACKGROUND AND PURPOSE OF THE STUDY

Intrathecal morphine (ITM) provides optimal postoperative analgesia in patients who are scheduled for total knee and hip operation with spinal anaesthesia. However, the ideal dose at which maximal analgesic effect occurs with minimal side effects is not known. This study aimed to describe the use of two doses of ITM and side effect profile in patients undergoing elective hip and knee arthroplasty.

METHODS

This was a prospective, descriptive, and contextual study conducted on patients who had total hip and knee replacement at Chris Hani Baragwanath Academic Hospital from 1 September to 30 November 2020. The sample size consisted of 66 patients who were 18 years and older, American Society of Anaesthesiology (ASA) classification 1-3, patients who had received either 100 mcg or 150 mcg ITM dose under spinal anaesthesia and sent to the ward postoperatively. Visual Analogue Scale (VAS) score was used to assess pain in the first 24 h, consumption of rescue analgesia and reported side effects were documented.

RESULTS

There was no relationship between age, weight, ASA classification or type of surgery and VAS score classification groups. Patients who received 100 mcg ITM had a higher median VAS pain score 2 (1-5) compared to those who received 150 mcg ITM 1 (0-2), p = 0.01. The need for rescue analgesia between the two groups was marginally less in the 150 mcg ITM group (p = 0.098). There was no difference in the rate of side effects between the 100 mcg ITM group [12 (41%)] and the 150 mcg ITM group [17 (59%)], p = 0.92. Rescue analgesia was marginally different between groups, p = 0.09. There were no real differences in the VAS pain scores between the total knee and total hip surgeries. None of the patients experienced clinically significant respiratory depression.

CONCLUSION

The 150 mcg ITM dose provided good analgesic effects with longer duration of action and comparable side effect profile to the 100 mcg ITM dose. This dose was not associated with development of respiratory depression and can therefore be administered safely to patients who are discharged to the ward postoperatively in a resource constraint environment.

Evaluation of the addition of bupivacaine to intrathecal morphine for intraoperative and postoperative pain management in open liver resections

BACKGROUND

Intrathecal morphine is a popular and effective regional technique for pain control after open liver resection, but its delayed analgesic onset makes it less useful for the intraoperative period. The aim of this retrospective study was to compare the analgesic efficacy and other secondary benefits of the addition of hyperbaric bupivacaine to intrathecal morphine ± fentanyl. We hypothesized that bupivacaine could serve as an analgesic "bridge" prior to the onset of intrathecal morphine/fentanyl thereby lowering opioid consumption and enhancing recovery.

METHODS

Cumulative intraoperative and postoperative opioid consumption as well as other intra- and postoperative variables were collected and compared between groups receiving intrathecal morphine alone or intrathecal morphine ± hyperbaric bupivacaine.

RESULTS

Sixty-eight patients were selected for inclusion. Cumulative intraoperative morphine consumption was significantly reduced in the bupivacaine group while other intraoperative parameters such as intravenous fluids, blood loss, and vasopressors did not differ. There was a statistically significant improvement in time to first bowel movement in the experimental group.

DISCUSSION

The intraoperative opioid sparing effects and improved time to bowel function with the addition of hyperbaric bupivacaine to intrathecal morphine may make this technique an easy and low risk method of enhancing recovery after open liver resection.

Zero Patient-controlled Analgesia is an Achievable Target for Postoperative Rapid Recovery Management of Adolescent Idiopathic Scoliosis Patients

STUDY DESIGN

Retrospective review.

OBJECTIVE

The objective of this study was to report on one institution's use of single bolus micro-dose intrathecal morphine as part of a rapid recovery pathway during posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) and its comparison to patients whose pain was controlled with patient-controlled analgesia (PCA).

SUMMARY OF BACKGROUND DATA

Narcotic substance addiction has risen across all patient populations, including pediatrics. Narcotics have been historically used in complex spine surgeries as a measure of pain control, predominantly provided as PCA and additional take-home medication.

METHODS

AIS patients undergoing PSF from 2015 to 2019 were reviewed. In 2018, we instituted a standardized rapid recovery pathway for scoliosis patients undergoing PSF utilizing micro-dose intrathecal morphine (ITM-RRP). Before this, traditional protocol with PCA was used for postoperative management. Perioperative data, morphine consumption and prescription refill requests were compared.

RESULTS

There were 373 AIS patients total in this study, of which 250 patients were in the PCA group and 123 in the ITM-RRP Group. Preoperative Cobb angles (P = 0.195), as well as levels fused (P = 0.481) and body mass index (P = 0.075) were similar. 69.4% of ITM-RRP patients had a length of stay ≤3 days, significantly >11.6% of PCA patients (P < 0.001). ITM-RRP patients began ambulating significantly earlier with 84.6% patients out of bed by postoperative day 1 versus 8% PCA patients (P < 0.001). Additionally, ITM-RRP patients had significantly lower VAS pain scores with activity and earlier initial bowel movements (P < 0.001).Postoperative emesis was similar (P = 0.11). No patients had pruritus, respiratory depression, or required supplemental oxygenation.

CONCLUSION

This is the first study to show that a rapid recovery protocol utilizing single micro-dose ITM with oral analgesics have adequate recovery, significantly better postoperative pain control and superior perioperative outcomes to traditional protocols using PCA in the AIS population following PSF.Level of Evidence: 3.

Intrathecal Morphine for Analgesia in Minimally Invasive Cardiac Surgery: A Randomized, Placebo-controlled, Double-blinded Clinical Trial

BACKGROUND

Intrathecal morphine decreases postoperative pain in standard cardiac surgery. Its safety and effectiveness have not been adequately evaluated in minimally invasive cardiac surgery. The authors hypothesized that intrathecal morphine would decrease postoperative morphine consumption after minimally invasive cardiac surgery.

METHODS

In this randomized, placebo-controlled, double-blinded clinical trial, patients undergoing robotic totally endoscopic coronary artery bypass received either intrathecal morphine (5 mcg/kg) or intrathecal saline before surgery. The primary outcome was postoperative morphine equivalent consumption in the first 24 h after surgery; secondary outcomes included pain scores, side effects, and patient satisfaction. Pain was assessed via visual analog scale at 1, 2, 6, 12, 24, and 48 h after intensive care unit arrival. Opioid-related side effects (nausea/vomiting, pruritus, urinary retention, respiratory depression) were assessed daily. Patient satisfaction was evaluated with the Revised American Pain Society Outcome Questionnaire.

RESULTS

Seventy-nine patients were randomized to receive intrathecal morphine (n = 37) or intrathecal placebo (n = 42), with 70 analyzed (morphine 33, placebo 37). Intrathecal morphine patients required significantly less median (25th to 75th percentile) morphine equivalents compared to placebo during first postoperative 24 h (28 [16 to 46] mg vs. 59 [41 to 79] mg; difference, -28 [95% CI, -40 to -18]; P < 0.001) and second postoperative 24 h (0 [0 to 2] mg vs. 5 [0 to 6] mg; difference, -3.3 [95% CI, -5 to 0]; P < 0.001), exhibited significantly lower visual analog scale pain scores at rest and cough at all postoperative timepoints (overall treatment effect, -4.1 [95% CI, -4.9 to -3.3] and -4.7 [95% CI, -5.5 to -3.9], respectively; P < 0.001), and percent time in severe pain (10 [0 to 40] vs. 40 [20 to 70]; P = 0.003) during the postoperative period. Mild nausea was more common in the intrathecal morphine group (36% vs. 8%; P = 0.004).

CONCLUSIONS

When given before induction of anesthesia for totally endoscopic coronary artery bypass, intrathecal morphine decreases use of postoperative opioids and produces significant postoperative analgesia for 48 h.

EDITOR’S PERSPECTIVE

The effect of ultrasound-guided serratus anterior plane block in addition to intrathecal morphine on early postoperative period after video-assisted thoracoscopic surgery

Background

The aim of this study was to evaluate the effect of serratus anterior plane block in addition to intrathecal morphine for early postoperative period after video-assisted thoracoscopic surgery on the amount of morphine consumption and the Visual Analog Scale scores.

Methods

This single-blind, randomized-controlled study included a total of 64 patients (39 males, 25 females; mean age: 53.6±17.0 years; range, 20 to 89 years) who were scheduled for video-assisted thoracoscopic surgery in a tertiary hospital between September 2019 and March 2020. Postoperative pain control was achieved with intrathecal morphine 0.6 mg addition to serratus anterior plane block (Group ITM+SAPB) or with only intrathecal morphine (Group ITM) after an induction of anesthesia. The serratus anterior plane block was performed with a single injection of 0.4 mL/kg of 0.25% bupivacaine at the level of fifth rib with ultrasound guidance. Morphine consumption, pain scores, and side effects were recorded in the postoperative period.

Results

The mean morphine consumption was significantly lower in the ITM+SAPB group at all time points. Compared to the control group, the Visual Analog Scale-resting and coughing scores were significantly lower in the first 12 h after surgery. Pain scores were significantly higher in the ITM+SAPB group in patients where the trocar was inserted at upper level of the fifth rib than the lower level (3-5 vs. 5-8) during the first 6 h after surgery.

Conclusion

The use of serratus anterior plane block in addition to intrathecal morphine is a safe and effective way to improve pain control for early postoperative period after video-assisted thoracoscopic surgery. The serratus anterior plane block ensures better analgesia until the peak effect of spinal morphine occurs.

Purely ropivacaine-based TEA vs single TAP block in pain management after elective laparoscopic colon surgery within an upgraded institutional ERAS program

Background

The aim of this study was to compare thoracic epidural analgesia (TEA) with transversus abdominis plane (TAP) block in post-operative pain management after laparoscopic colon surgery.

Methods

One hundred thirty-six patients undergoing laparoscopic colon resection randomly received either TEA or TAP with ropivacaine only. The primary endpoint was opioid requirement up to 48 h postoperatively. Intensity of pain, time to onset of bowel function, time to mobilization, postoperative complications, length of hospital stay, and patients’ satisfaction with pain management were also assessed.

Results

We observed a significant decrease in opioid consumption on the day of surgery with TEA compared with TAP block (30 mg vs 14 mg, p < 0.001). On the first two postoperative days (POD), the balance shifted to opioid consumption being smaller in the TAP group: on POD 1 (15.2 mg vs 10.6 mg; p = 0.086) and on POD 2 (9.2 mg vs 4.6 mg; p = 0.021). There were no differences in postoperative nausea/vomiting or time to first postoperative bowel movement between the groups. No direct blockade-related complications were observed and the length of stay was similar between TEA and TAP groups.

Conclusion

TEA is more efficient for acute postoperative pain than TAP block on day of surgery, but not on the first two PODs. No differences in pain management-related complications were detected.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00464-021-08647-z.

[Neuraxial Morphine for Postoperative Analgesia after Caesarean Deliveries]

The use of neuraxial morphine, in combination with nonopioid analgesic regimens for postoperative analgesia after Caesarean deliveries is common practice, especially in the Anglo-American world. Neuraxial morphine offers a longer-lasting superior analgesia than intravenous opioids or patient-controlled analgesia. If neuraxial anaesthesia is being used for a caesarean delivery, it may be recommended to concomitantly administer neuraxial morphine for the postoperative analgesia.A low dose of neuraxial morphine in a healthy parturient bears a low morbidity and mortality risk. The optimal frequency, duration and modality of respiratory monitoring for patients at low risk for respiratory depression is dependent on the dose of morphine administered and the patient-specific and obstetric risk profile.

Effects of opioid-reduced anesthesia during scoliosis surgery in children: a prospective observational study

Aims: Opioid-reduced anesthesia (ORA) was suggested to decrease morphine consumption after adolescent idiopathic scoliosis (AIS) surgery and incidence of chronic pain. Materials & methods: A prospective analysis using the ORA in AIS surgery was performed. Two cohorts were compared: a control group (opioid-based anesthesia) and the ORA group. The main outcome was morphine consumption at day 1. Results: 33 patients operated for AIS using ORA were compared with 36 with opioid-based anesthesia. Morphine consumption was decreased in the ORA group (1.1 mg.kg^-1 [0.2-2] vs 0.8 mg.kg^-1 [0.3-2]; p = 0.02) at day 1. Persistent neuropathic pain at 1 year was decreased in the ORA group (p = 0.02). Conclusion: The ORA protocol is efficient to reduce postoperative morphine consumption in AIS surgery and preventing neuropathic pain.

A Literature Review of Intrathecal Morphine Analgesia in Patients Undergoing Major Open Hepato-Pancreatic-Biliary (HPB) Surgery

CONTEXT

The optimal analgesic method for patients undergoing major open hepato-pancreatic-biliary surgery remains controversial. Continuous epidural infusion at the thoracic level remains the standard choice, however concerns have been raised due to associated complications. Single shot intrathecal morphine has emerged as a promising alternative offering similar analgesia with an enhanced safety profile.

EVIDENCE ACQUISITION

This review aimed to evaluate the literature comparing intrathecal morphine analgesia to other analgesic modalities following major open hepato-pancreatic-biliary surgery. The primary outcome was pain scores at rest and on movement 24 h after surgery. Secondary outcomes were postoperative opioid consumption within 72 postoperative hours, length of stay (LOS), intra-operative fluid administration and post-operative fluid administration within 72 postoperative hours, and overall systemic complication rate within 30 postoperative days.

RESULTS

Eleven trials matching the inclusion criteria were analysed. Intrathecal morphine resulted in equivalent or lower pain scores when contrasted to alternative techniques, but required higher amounts of postoperative opioid. Intrathecal morphine also offered reduced LOS and reduced fluid administration requirements to epidural analgesia, and there was no difference observed in major complication rate between analgesic modalities.

CONCLUSIONS

In summary the evidence suggests that intrathecal morphine may be a better first-line analgesic modality than epidural analgesia in the context of major open hepato-pancreatic-biliary surgery, but high-quality evidence supporting this is limited.

Addition of Intrathecal Morphine for Postoperative Pain Management in Pediatric Spine Surgery: A Meta-analysis

STUDY DESIGN

Meta-analysis.

OBJECTIVE

The objective of this study was to determine whether adjunctive intrathecal morphine (ITM) reduces postoperative analgesic consumption following pediatric spine surgery.

SUMMARY OF BACKGROUND DATA

Previous studies that have tested supplemental ITM to manage pain after pediatric spine surgery have been limited by small sample sizes.

METHODS

A comprehensive search of PubMed, Web of Science, Clinicaltrials.gov, and the Cochrane Central Register of Controlled Trials was performed for clinical trials and observational studies. Time to first analgesic demand, postoperative analgesic use, pain scores, and complication data were abstracted from each study. Mean difference (MD) and 95% confidence interval (CI) were used to compare continuous outcomes and odds ratios (OR) and 95% CI were used for dichotomous outcomes.

RESULTS

A total of 5 studies, including 3 randomized controlled trials and 2 retrospective chart reviews, containing 636 subjects, were incorporated into meta-analysis. Subjects that were administered ITM in addition to postoperative analgesics (ITM group) were compared with those receiving postoperative analgesics only (control group). In the ITM group, time to first analgesic demand was longer (MD, 8.79; 95% CI, 4.20-13.37; P<0.001), cumulative analgesic consumption was reduced at 24 hours (MD, -0.40; 95% CI, -0.56 to -0.24; P<0.001), and cumulative analgesic consumption was reduced at 48 hours (MD, -0.43; 95% CI, -0.59 to -0.27; P<0.001). Neither postoperative pain scores at 24 hours (P=0.16) nor 48 hours (P=0.18) were significantly different between ITM and control groups. Rates of respiratory depression, nausea, vomiting, and pruritus were not different between groups (all Ps>0.05).

CONCLUSIONS

Addition of ITM in pediatric spine surgery produced a potent analgesic effect in the immediate postoperative period. Patients administered ITM did not request opiates as early as control and consumed fewer opiates by the second postoperative day. Furthermore, use of ITM did not increase complications such as respiratory depression, nausea, vomiting, or pruritus.

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.

Characteristics of Desaturation and Respiratory Rate in Postoperative Patients Breathing Room Air Versus Supplemental Oxygen: Are They Different?

BACKGROUND

Routine monitoring of postoperative patients with pulse oximetry-based surveillance monitoring has been shown to reduce adverse events. However, there is some concern that pulse oximetry is limited in its ability to detect deterioration quickly enough to allow for intervention in patients receiving supplemental oxygen. To address such concerns, this study expands on the current limited knowledge of differences in desaturation and respiratory rate characteristics between patients breathing room air and those receiving supplemental oxygen.

METHODS

Pulse oximetry-derived data and patient characteristics were used to examine overnight desaturation patterns of 67 postoperative patients who were receiving either supplemental oxygen or breathing room air. The 2 modalities with respect to the speed of desaturation, in addition to magnitude and duration of desaturation events, are compared. Night-time pulse rate, oxygen saturation, respiratory rate, and the transition times from normal oxygen saturation levels to desaturated states are also compared. The behavior of respiratory rate in proximity to desaturation events is described. Statistical methods included multivariable regression and inverse probability of treatment weighted to adjust for any imbalance in patient characteristics between the oxygen and room air patients and linear mixed effect models to account for clustering by patient.

RESULTS

The study included 33 patients on room air and 34 receiving supplemental oxygen. The speed of desaturation was not different for room air versus oxygen for 2 types of desaturation (adjusted % difference, 95% confidence interval [CI]: type I; 22.4%, -51.5% to 209%; P = .67, type II; -17.3%, -53.8% to 47.6%; P = .52). Patients receiving supplemental oxygen had a higher mean oxygen saturation (adjusted difference, 95% CI, 2.4 [0.7-4.0]; P = .006). No differences were found for the average overnight respiratory or pulse rate, or proportion of time in desaturation states between the 2 groups.The time to transition from a normal oxygen saturation (92%) to 88% or below was not longer for supplemental oxygen patients (P = .42, adjusted difference 26.1%: 95% CI, -28.1% to 121%). Respiratory rates did not differ between the overall mean and desaturation or recovery phases or between the oxygen and room air group.

CONCLUSIONS

In this study, desaturation characteristics did not differ between patients receiving supplemental oxygen and breathing room air with regard to speed, depth, or duration of desaturation. Transition time for desaturations to reach low oxygen saturation alarms was not different, while respiratory rate remained in the normal range during these events. These findings suggest that pulse oximetry-based surveillance monitoring for deterioration detection can be used equally effectively for patients on supplemental oxygen and for those on room air.

Pruritus and postoperative nausea and vomiting after intrathecal morphine in spinal anaesthesia for caesarean section: Prospective cohort study

Background:

Spinal anaesthesia is a common anaesthetic technique for caesarean sections. Neuraxial opioids such as intrathecal morphine may cause common adverse effects (pruritus, post-operative nausea and vomiting).

Objectives:

We investigated the incidence, severity and need for treatment of pruritus and post-operative nausea and vomiting following administration of intrathecal morphine in spinal anaesthesia for caesarean section at KK Women’s and Children’s Hospital, Singapore.

Methods:

We conducted a prospective study involving 124 parturients who received intrathecal morphine in spinal anaesthesia for caesarean section from October 2012 to October 2014.

Results:

Seventy patients (56.5%) had moderate or severe pruritus (score 4–10), while 54 patients (43.5%) had no or mild pruritus (score 0–3). Mean (SD) value of the worst pruritus score reported on a scale of 0–10 was 4 (2.59). Only seven out of the 124 patients (5.6%) required treatment for pruritus. With respect to distress and bother from itching in the past 24 hours on a score of 0–4, the mean score reported was 1.7 (1.23). Fourteen (11.2%) patients reported vomiting, dry-retching and nausea. Six (4.8%) patients had nausea that interfered with activities of daily living. Four (3.2%) patients had clinically significant post-operative nausea and vomiting. Seven (5.6%) patients received anti-emetics. The average Overall Benefit of Analgesia Score was 3.8 (SD 2.6, min–max: 0–15). The average (SD) maternal satisfaction with pain relief and side effects was 84.9% (9.9%).

Conclusion:

There is a high incidence of pruritus, with most women reporting moderate to severe pruritus. The incidence of post-operative nausea and vomiting is low, and women reported good maternal satisfaction.

Prevalence and management of intrathecal morphine-induced pruritus in New Zealand Māori healthcare recipients

Aims and objectives

The aim of this article was to determine whether the incidence of intrathecal morphine-induced pruritus (ITMI) was influenced by ethnicity, age or gender in relation to orthopaedic versus caesarean surgeries.

Background

The use of intrathecal morphine for patients undergoing total hip and knee joint replacements and for lower segment caesarean sections (LSCS) has gained popularity worldwide since its introduction over 30 years ago. Several international studies show that morphine delivered via the intrathecal route is an effective and safe method of pain relief. However, while the beneficial effects of intrathecal morphine have been clearly documented in many studies, so also have the adverse effects, predominantly being nausea and vomiting, pruritus and respiratory depression. Pruritus is described as one of the most common adverse effects, with a reported incidence of 30-100%.

Design

A retrospective study was conducted using data collected over a 21-month period on post-operative patients who had received intrathecal morphine as their post-operative pain management.

Methods

A two-phased approach was undertaken. The study was conducted to determine the incidence of ITMI pruritus among two patient groups, New Zealand Māori and New Zealand European, 96 subjects in total, and if treatment was received.

Results

The findings revealed significant ethnic disparities whereas New Zealand Māori had a significantly higher rate of ITMI pruritus than New Zealand European, New Zealand Māori experienced the pruritus with more intensity and are less likely to be treated for it.

Conclusion

Increased international knowledge and awareness for health professionals around the diversities of ethnicity and associated pharmacogenetics playing a significant role in patient response to opioid therapy can lead to improved overall care and patient satisfaction.

The NAPRESSIM trial: the use of low-dose, prophylactic naloxone infusion to prevent respiratory depression with intrathecally administered morphine in elective hepatobiliary surgery: a study protocol and statistical analysis plan for a randomised controlled trial

BACKGROUND

Intrathecally administered morphine is effective as part of a postoperative analgesia regimen following major hepatopancreaticobiliary surgery. However, the potential for postoperative respiratory depression at the doses required for effective analgesia currently limits its clinical use. The use of a low-dose, prophylactic naloxone infusion following intrathecally administered morphine may significantly reduce postoperative respiratory depression. The NAPRESSIM trial aims to answer this question.

METHODS/DESIGN

'The use of low-dose, prophylactic naloxone infusion to prevent respiratory depression with intrathecally administered morphine' trial is an investigator-led, single-centre, randomised, double-blind, placebo-controlled, double-arm comparator study. The trial will recruit 96 patients aged > 18 years, undergoing major open hepatopancreaticobiliary resections, who are receiving intrathecally administered morphine as part of a standard anaesthetic regimen. It aims to investigate whether the prophylactic administration of naloxone via intravenous infusion compared to placebo will reduce the proportion of episodes of respiratory depression in this cohort of patients. Trial patients will receive an infusion of naloxone or placebo, commenced within 1 h of postoperative extubation continued until the first postoperative morning. The primary outcome is the rate of respiratory depression in the intervention group as compared to the placebo group. Secondary outcomes include pain scores, rates of nausea and vomiting, pruritus, sedation scores and adverse outcomes. We will also employ a novel, non-invasive, respiratory minute volume monitor (ExSpiron 1Xi, Respiratory Motion, Inc., 411 Waverley Oaks Road, Building 1, Suite 150, Waltham, MA, USA) to assess the monitor's accuracy for detecting respiratory depression.

DISCUSSION

The trial aims to provide a clear management plan to prevent respiratory depression after the intrathecal administration of morphine, and thereby improve patient safety.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT02885948 . Registered retrospectively on 4 July 2016. Protocol Version 2.0, 3 April 2017. Protocol identification (code or reference number): UCDCRC/15/006 EudraCT registration number: 2015-003504-22. Registered on 5 August 2015.

A randomized double-blind controlled trial comparing three sedation regimens during flexible bronchoscopy: Dexmedetomidine, alfentanil and lidocaine

INTRODUCTION

No standardized sedation protocol is available for flexible bronchoscopy (FB).

OBJECTIVES

The aim of this study was to evaluate the efficacy and safety of three regimens used for sedation during FB.

METHODS

This randomized double-blind controlled trial assessed patients undergoing bronchoscopy and receiving lidocaine alone (C) or combined with dexmedetomidine (D) or alfentanil (A). Tolerance was assessed using the bronchoscopy score, and level of sedation was assessed using the Nursing Instrument for the Communication of Sedation. Safety was evaluated in terms of pulmonary function and vital signs.

RESULTS

A total of 162 patients were enrolled. The bronchoscopy score was identical in all groups. Group D subjects were the most sedated (P = .013), whereas group A subjects were the least agitated. Linear regression showed a negative association between bronchoscopy score and age in A (β = -0.06; P = .001). Positive predictors of bronchoscopy score were female gender (β = 1.96; P = .003) in D and obesity (β = 2.41; P = .012), longer procedures (β = 0.08; P = .009) and female gender (β = 1.15; P = .038) in C. Longer procedures (β = -0.12; P = .010) was a negative predictor of bronchoscopy score in D. Desaturation, hypoxia and heart rate changes were most prevalent in group A. Hypotension was mostly observed in D.

CONCLUSIONS

No consistent differences were present between the three regimens; however, each was more appropriate in certain patient profiles. We consequently proposed a protocol as a first step towards standardizing sedation practice in FB in a patient-tailored manner. A more comprehensive and detailed protocol including other sedative agents with their corresponding doses should be developed.

A prospective study of post-cesarean delivery hypoxia after spinal anesthesia with intrathecal morphine 150μg

INTRODUCTION

Delayed respiratory depression is a feared complication of intrathecal morphine in patients undergoing cesarean delivery. The incidence, timing and risk factors for hypoxia in this population are not known.

METHODS

Patients undergoing cesarean delivery under spinal anesthesia at a tertiary care center from October 2012 to March 2016 were included in the study. The Berlin sleep apnea Questionnaire was completed before surgery. Oxygen saturation was recorded every second for 24hours after the initiation of spinal anesthesia. Desaturation events were defined as a median saturation of <90% (mild) or <85% (severe) across a 30-s period. Multivariable logistic regression was used to determine predictors of a desaturation event.

RESULTS

A total of 721 patients were included in the analysis. Within this cohort, 169 women (23%) experienced at least one mild desaturation event, 91 (13%) experienced two or more mild desaturations, and 26 (4%) suffered a severe desaturation event. After the administration of intrathecal morphine, the median times to first mild or first severe desaturation were 7.4 (IQR 4.1-13.5)h and 12.0 (IQR 5.4-19.6)h, respectively. Patients who screened positive for sleep apnea had increased odds of having a mild desaturation event (OR 2.31, 95% CI 1.40 to 3.79, P=0.001), as did patients who were obese (OR 1.80, 95% CI 1.05 to 3.09, P=0.033).

CONCLUSIONS

Mild hypoxemia occurred frequently in women receiving intrathecal morphine 150μg for post-cesarean analgesia. Desaturations were observed most frequently 4-8hours after administration of intrathecal morphine. Obesity and a positive Berlin Questionnaire were risk factors for hypoxemic events.

Applying realistic medicine to intrathecal opioid utilisation in Scotland: do we have a standardised approach?

Intrathecal opioids (ITOs) are commonly administered as part of a multimodal anaesthetic strategy for a variety of surgical procedures. The evolution of laparoscopic surgical techniques has seen the popularity of ITOs increase as they are effective, well tolerated and lack the cardiovascular side effects associated with epidural infusions. The risk of delayed respiratory depression remains a concern; therefore, high-quality post-operative monitoring is vital. The evidence regarding the practicalities of ITO administration such as opioid dose, type, side effect prevalence and ideal post-operative care arrangements are sparse. As such, a variety of clinical opinion has been generated. In order to quantify this variation within Scotland, we devised a short telephone questionnaire regarding ITO utilisation. We contacted 16 acute surgical sites. Of these, 14 confirmed regular utilisation of ITOs. Our survey demonstrated significant variability in practice. Both diamorphine and morphine are utilised, but no centre could provide a reason to justify the choice of one over the other. The commonly administered dose range for both agents ranged between 100 and 1100 µg. Most centres employed post-operative monitoring geared towards the detection of delayed respiratory depression but this was not unanimous. Each centre had a variation on what observations nursing staff were expected to complete in the post-operative period. Itch and nausea were not encountered frequently. Two centres experienced at least one episode of delayed respiratory depression which was detected and treated with no patient harm. In the report to the Scottish Government, 'Realistic Medicine', by the Chief Medical Officer, the need to reduce unnecessary variation in practice and outcomes is highlighted. We believe that a national sprint audit would gather sufficient prospective data to further determine whether a correlation exists between side effect profile and ITO utilisation practice. We hope this would help form a consensus and guide a standardised approach.

Microemboli and Neurologic Dysfunction After Cardiovascular Surgery

Several recent studies have shown that cardiac surgery poses significant risks for negative neurologic and neu ropsychological outcome. Death and major stroke have become uncommon consequences of cardiac surgery, but more than two-thirds of the patients show evidence of neuropsychological dysfunction postoperatively.

The mechanisms contributing to postcardiopulmonary bypass neuropsychological deficits are uncertain, and potentially there are many possible causative factors that may play a significant role in perioperative neuro logic injury. However, two major interrelated factors, hypoperfusion and emboli, are suggested as probable culprits. Perfusion is important because the level of global and focal cerebral blood flow during periods of high embolic risk will determine the amount of brain embolization as well as the localization of the lesions. Ultrasonically detected macroemboli have been re ported to be the best predictor of neurobehavioral outcome. Microemboli found in autopsy specimens may also be important predictors of negative outcome. The relationship between microemboli and changes in brain function, as detected by magnetic resonance spectroscopy, may provide further insight into the prob ability of the clinical expression of a neurobehavioral dysfunction after cardiac surgery.

The incidence and severity of neuropsychological defi cits after cardiac surgery appear to be related to the delivery of macroemboli. The composition of the embo lus may be the most important determinant of the level and volume of focal injury, but the time of occurrence (ie, rewarming) of macroemboli during cardiopulmo nary bypass may also be important in determining the effect of emboli on neuropsychological outcome. How ever, the key variable in the manifestation of neurobe havioral dysfunction remains the location of the lesion site.

Comparative study between nalbuphine and ondansetron in prevention of intrathecal morphine-induced pruritus in women undergoing cesarean section

BACKGROUND

Intrathecal morphine provides effective postoperative analgesia, but their use is associated with numerous side effects, including pruritus, nausea, vomiting, urinary retention, and respiratory depression. Pruritus is the most common side effect with a reported incidence of 58-85%.

OBJECTIVES

This prospective, randomized, and double-blinded study was performed for women scheduled for cesarean delivery using spinal anesthesia to compare nalbuphine and ondansetron in the prevention of intrathecal morphine-induced pruritus.

PATIENTS AND METHODS

Ninety women after spinal anesthesia with hyperbaric bupivacaine and intrathecal morphine patients randomly divided into three groups. Women in placebo group (P group) received 4 ml of normal saline intravenous (IV) injection, nalbuphine group (N group) received 4 ml of a 4 mg nalbuphine IV injection, and ondansetron 4 group (O group) received 4 ml of a 4 mg ondansetron IV injection, immediately after delivery of the baby. Studied women observed in postanesthesia care unit for 4 h. The primary outcome measures success of the treatment, defined as a pruritus score 1 (no pruritus) or 2 (mild pruritus - no treatment required) at 20 min after treatment.

RESULTS

Although, three was no significant difference between the three studied groups regarding; score 1 pruritus, while, score 2 pruritus (mild pruritus - no treatment requested) was significantly high in N and O groups compared to placebo group. Pruritus score 1 (no pruritus) plus pruritus score 2 were significantly high in N and O groups compared to placebo group (20 cases, 20 cases, 5 cases; respectively, P = 0.008). In addition; score 3 pruritus (moderate - treatment requested) was significantly less in N and O groups compared to placebo group.

CONCLUSION

Nalbuphine and ondansetron were found to be more effective than placebo for prevention of intrathecal morphine-induced pruritus in women undergoing cesarean delivery and nalbuphine is preferred than ondansetron because it is not excreted in the breast milk.

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.

Neuraxial opioid-induced itch and its pharmacological antagonism

Given its profound analgesic nature, neuraxial opioids are frequently used for pain management. Unfortunately, the high incident rate of itch/pruritus after spinal administration of opioid analgesics reported in postoperative and obstetric patients greatly diminishes patient satisfaction and thus the value of the analgesics. Many endeavors to solve the mystery behind neuraxial opioid-induced itch had not been successful, as the pharmacological antagonism other than the blockade of mu opioid receptors remains elusive. Nevertheless, as the characteristics of all opioid receptor subtypes have become more understood, more studies have shed light on the potential effective treatments. This review discusses the mechanisms underlying neuraxial opioid-induced itch and compares pharmacological evidence in nonhuman primates with clinical findings across diverse drugs. Both nonhuman primate and human studies corroborate that mixed mu/kappa opioid partial agonists seem to be the most effective drugs in ameliorating neuraxial opioid-induced itch while retaining neuraxial opioid-induced analgesia.

Intrathecal morphine for postoperative analgesia: Current trends

The practice of anesthesiology has always been governed by evidence-based medicine. The quick turnover rate of patients in the operating room and patient safety and satisfaction, have also further changed the way we practice anesthesia. The use of intrathecal (IT) opiates as an effective form of postoperative pain relief has been established for many years. Morphine was the first opioid used by IT route. In clinical practice, morphine is regarded as the gold standard, or benchmark, of analgesics used to relieve intense pain. Perhaps for this reason, IT morphine has been used for over 100 years for pain relief. IT morphine is one of the easiest, cost-effective and reliable techniques for postoperative analgesia and technical failures are rare. And yet there is no consensus amongst anesthesiologists regarding the dose of IT morphine. Like all other methods of pain relief, IT morphine also has some side effects and some of them are serious though not very common. This review article looks into some of the key aspects of the use of IT morphine for post-operative analgesia and various doses for different procedures are discussed. This article also describes the side effects of IT morphine and how to treat and prevent them.

Reversible paralysis and loss of deep pain sensation after topical intrathecal morphine administration following durotomy

OBJECTIVE

To report 2 dogs that developed temporary pelvic limb paralysis with loss of deep pain sensation after topical intrathecal morphine administration during spinal surgery.

STUDY DESIGN

Clinical report.

ANIMALS

Dogs (n = 2).

METHODS

A 5-year-old castrated male French Bulldog with a subarachnoid diverticulum at T9-T10 and a 9.5-year-old castrated male Belgian Shepherd dog with a herniated disc at T12-T13 and intradural component, had Gelfoam soaked with morphine placed over the dura mater defect.

RESULTS

Pelvic limb paralysis and loss of deep pain sensation was noticed immediately after recovery from anesthesia. After intravenous naloxone administration, both dogs immediately regained ambulation and normal pain sensation; however the effect was temporary lasting only a few hours. Permanent resolution of clinical signs occurred 24 hours after surgery.

CONCLUSIONS

Topical intrathecal morphine administration resulted in temporary pelvic limb paralysis and loss of deep pain sensation. This route of administration should be used cautiously until further determination of the efficacy and adverse effects associated with topical intrathecal morphine administration.

Bupivacaine-sufentanil versus bupivacaine-fentanyl in spinal anesthesia of patients undergoing lower extremity surgery

BACKGROUND

The addition of intrathecal opioids to local anesthetics seems to improve the quality of analgesia and prolong the duration of analgesia, when using a subarachnoid block in Iranian patients with their specific pain tolerance.

OBJECTIVES

The aim of this study was to evaluate the effects of adding fentanyl or sufentanil, to intrathecal bupivacaine, in terms of the onset and duration of; sensory block, motor block, hemodynamic effects and postoperative pain relief.

PATIENTS AND METHODS

This randomized clinical trial included 90 patients who underwent orthopedic lower limb surgeries. Subjects were divided into experimental groups; intrathecal fentanyl 25 µg (F), and sufentanil 2.5 µg (S), along with a placebo 0.5 mL normal saline (C) group, which were added to bupivacaine 0.5%, 15 mg. Duration of complete and effective analgesia was recorded (by a visual analogue scale-VAS). The pain scores were assessed postoperatively. Intraoperative mean arterial pressure (MAP), heart rate and oxygen saturation (SPO(2)) were recorded. The incidence of side effects such as; nausea, vomiting, pruritus, shivering, bradycardia and hypotension were also recorded.

RESULTS

MAP and heart rate results showed no significant changes at the designated time points among the three groups (P > 0.05). However, SPO2 and VAS showed significant changes at the designated time points among the three groups (P < 0.05). The duration of complete and effective analgesia was also significantly longer in the sufentanil group (P < 0.05). Motor block did not exhibit any significant difference (P = 0.67). Only pruritus as a side effect was significantly higher in the sufentanil group (P < 0.05), while all other evaluated side effects were significantly lower in the sufentanil group (P < 0.05).

CONCLUSIONS

The addition of 2.5-3 mcg sufentanil to 15 mg 0.05% bupivacaine maintained the patient's hemodynamic stability similar to fentanyl. Intrathecal sufentanil added to bupivacaine,when compared with fentanyl, may lead to prolonged duration of analgesia, facilitate the spread of the sensory block, increase mean SPO2 levels, and reduce overall side effects.

Highlights in opioid agonists and antagonists

This review highlights new insights in to opioid agonists and antagonists, focusing on their mechanism of action with spinal and systemic administration, chronic use and main adverse effects. Short-cuts on some opioid agonists and antagonists of clinical interest are also presented, revealing potential clinical implications and future clinical directions as part of multimodal analgesia.

Effects of anesthetics, sedatives, and opioids on ventilatory control

This article provides a comprehensive, up to date summary of the effects of volatile, gaseous, and intravenous anesthetics and opioid agonists on ventilatory control. Emphasis is placed on data from human studies. Further mechanistic insights are provided by in vivo and in vitro data from other mammalian species. The focus is on the effects of clinically relevant agonist concentrations and studies using pharmacological, that is, supraclinical agonist concentrations are de-emphasized or excluded.

Cardiorespiratory complications of neuraxial opioids in patients with obstructive sleep apnea: a systematic review

We sought to determine the rate of cardiorespiratory complications following neuraxial opioid administration in the setting of obstructive sleep apnea (OSA). This systematic review of the leading biomedical databases originated from a university-affiliated, tertiary-care teaching hospital. A systematic search of Medline, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and the International Pharmaceutical Abstracts Database (1970 - September 2011) was undertaken. Cardiorespiratory complications were stratified into minor and major based on existing OSA literature. Five studies, including a total of 121 patients, were selected for analysis. All studies comprised low-quality evidence. Six major cardiorespiratory complications were reported among 5 (4.1%) patients and included three deaths, one cardiorespiratory arrest, and two episodes of severe respiratory depression. Five of these complications occurred during continuous fentanyl-containing epidural infusions and without concurrent positive airway pressure treatment. The rate of cardiorespiratory complications following the administration of neuraxial opioids to surgical patients with OSA is difficult to determine.

The therapeutic potential of nociceptin/orphanin FQ receptor agonists as analgesics without abuse liability

Although mu opioid (MOP) receptor agonists are the most commonly used analgesics for the treatment of moderate to severe pain in the clinic, the side effects of MOP agonists such as abuse liability limit their value as a medication. Research to identify novel analgesics without adverse effects is pivotal to advance the health care of humans. The nociceptin/orphanin FQ peptide (NOP) receptor, the fourth opioid receptor subtype, mediates distinctive actions in nonhuman primates which suggests the possibility that activity at this receptor may result in strong analgesia in the absence of virtually all of the side effects associated with MOP agonists. The present review highlights the recent progress of pharmacological studies of NOP-related ligands in primates. Selective NOP agonists, either peptidic or nonpeptidic, produce full analgesia in various assays in primates, when delivered systemically or intrathecally. Yet small molecule NOP agonists do not serve as reinforcers, indicating a lack of abuse liability. Given that NOP agonists have low abuse liability and that coactivation of NOP and MOP receptors produces synergistic antinociception, it is worth developing bifunctional NOP/MOP ligands. The outcomes of these studies and recent developments provide new perspectives to establish a translational bridge for understanding the biobehavioral functions of NOP receptors in primates and for facilitating the development of NOP-related ligands as a new generation of analgesics without abuse liability in humans.

Continuous intrathecal morphine administration for cancer pain management using an intrathecal catheter connected to a subcutaneous injection port: a retrospective analysis of 22 terminal cancer patients in korean population

Background

Intrathecal opioid administration has been used widely in patients suffering from severe cancer pain that is not managed with conventional modalities. However, the potential serious neurological complications from the procedure and the side effects of intrathecal opioids have made many clinicians reluctant to employ continuous intrathecal analgesia as a first-line therapeutic option despite its dramatic effect on intractable pain. We retrospectively investigated the efficacy, side effects, and complications of intrathecal morphine administration through intrathecal catheters connected to a subcutaneous injection port (ICSP) in 22 Korean terminal cancer patients with successful intrathecal morphine trials.

Methods

Patient demographic data, the duration of intrathecal opioid administration, preoperative numerical pain rating scales (NRS) and doses of systemic opioids, side effects and complications related to intrathecal opioids and the procedure, and the numerical pain rating scales and doses of intrathecal and systemic opioids on the 1^st, 3^rd, 7^th and 30^th postoperative days were determined from medical records.

Results

Intrathecal morphine administration for 46.0 ± 61.3 days significantly reduced NRS from baseline on all the postoperative days. A significant increase in intrathecal opioids with a nonsignificant decrease in systemic opioids was observed on the 7^th and 30^th postoperative days compared to the 1^st postoperative day. The most common side effects of intrathecal opioids were nausea/vomiting (31.8%) and urinary retention (38.9%), which were managed with conservative therapies.

Conclusions

Intrathecal morphine administration using ICSP provided immediate and beneficial effects on pain scores with tolerable side effects in terminal cancer patients.

Roles of μ-opioid receptors and nociceptin/orphanin FQ peptide receptors in buprenorphine-induced physiological responses in primates

Buprenorphine is known as a μ-opioid peptide (MOP) receptor agonist, but its antinociception is compromised by the activation of nociceptin/orphanin FQ peptide (NOP) receptors in rodents. The aim of this study was to investigate the roles of MOP and NOP receptors in regulating buprenorphine-induced physiological responses in primates (rhesus monkeys). The effects of MOP antagonist (naltrexone), NOP antagonist [(±)-1-[(3R*,4R*)-1-(cyclooctylmethyl)-3-(hydroxymethyl)-4-piperidinyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J-113397)], and NOP agonists [(1S,3aS)-8-(2,3,3a,4,5,6-hexahydro-1H-phenalen-1-yl)-1-phenyl-1,3,8-triaza-spiro[4.5] decan-4-one (Ro 64-6198) and 3-endo-8-[bis(2-methylphenyl)methyl]-3-phenyl-8-azabicyclo[3.2.1]octan-3-ol (SCH 221510)] on buprenorphine were studied in three functional assays for measuring analgesia, respiratory depression, and itch in primates. Over the dose range of 0.01 to 0.1 mg/kg, buprenorphine dose-dependently produced antinociception, respiratory depression, and itch/scratching responses, and there was a ceiling effect at higher doses (0.1-1 mg/kg). Naltrexone (0.03 mg/kg) produced similar degrees of rightward shifts of buprenorphine's dose-response curves for all three endpoints. Mean pK(B) values of naltrexone (8.1-8.3) confirmed that MOP receptors mediated mainly buprenorphine-induced antinociception, respiratory depression, and itch/scratching. In contrast, J-113397 (0.1 mg/kg) did not change buprenorphine-induced physiological responses, indicating that there were no functional NOP receptors in buprenorphine-induced effects. More importantly, both NOP agonists, Ro 64-6198 and SCH 221510, enhanced buprenorphine-induced antinociception without respiratory depression and itch/ scratching. The dose-addition analysis revealed that buprenorphine in combination with the NOP agonist synergistically produced antinociceptive effects. These findings provided functional evidence that the activation of NOP receptors did not attenuate buprenorphine-induced antinociception in primates; instead, the coactivation of MOP and NOP receptors produced synergistic antinociception without other side effects. This study strongly supports the therapeutic potential of mixed MOP/NOP agonists as innovative analgesics.

A comparison of epidural magnesium and/or morphine with bupivacaine for postoperative analgesia after cesarean section

BACKGROUND

Magnesium can potentiate the antinociceptive effect of morphine. This prospective randomized double-blinded study was undertaken to establish the analgesic effect of adding magnesium to epidural morphine during cesarean section.

METHODS

Two hundred patients undergoing cesarean section under combined spinal-epidural anesthesia were recruited. After administration of intrathecal bupivacaine 10mg, patients were randomly assigned to receive one of four epidural study solutions: 0.1% bupivacaine 10 mL (Group B); 0.1% bupivacaine 10 mL and morphine 1.5mg (Group B+Mor); 0.1% bupivacaine 10 mL and magnesium 500 mg (Group B+Mg); or 0.1% bupivacaine 10 mL morphine 1.5mg and magnesium 500 mg (Group B+Mor+Mg). The primary outcome was the area under the curve for visual analog scale pain scores during 36 h postoperatively. Secondary outcomes included time to the use of rescue analgesics, patient satisfaction and side effects.

RESULTS

Patients in Group B+Mor+Mg had lower for pain scores and area under the curve pain scores both at rest and on movement, increased time for first analgesic request, and increased satisfaction score at 24h after surgery.

CONCLUSION

Addition of magnesium 500 mg and morphine 1.5mg to epidural 0.1% bupivacaine 10 mL reduced postoperative pain compared with addition of morphine or magnesium alone or no additive.

A clinical approach to neuraxial morphine for the treatment of postoperative pain

Opioids are considered a “gold standard” in clinical practice for the treatment of postoperative pain. The spinal administration of an opioid drug does not guarantee selective action and segmental analgesia in the spine. Evidence from experimental studies in animals indicates that bioavailability in the spinal cord biophase is negatively correlated with liposolubility, and is higher for hydrophilic opioids, such as morphine, than lipophilic opioids, such as fentanyl, sufentanil and alfentanil. Epidural morphine sulphate has proven analgesic efficacy and superiority over systemically administered morphine for improving postoperative pain. However, pain relief after a single epidural injection of morphine could last less than 24 hours. Techniques used to administered and prolong opioid epidural analgesia, can be costly and inconvenient. Moreover, complications can arise from indwelling epidural catheterization, particularly in patients receiving anticoagulants. Clinical trials have shown that epidural morphine in the form of extended-release liposome injections (EREM) gives good analgesia for a period of 48 hours, with no need for epidural catheterisation. Intrathecal morphine produces intense analgesia for up to 24 hours with a single shot, and clinical recommendation is to choose the minimum effective dose and do not exceed 300 μg to prevent the delay respiratory depression.

[Postoperative nausea and vomiting and opioid-induced nausea and vomiting: guidelines for prevention and treatment]

Postoperative nausea and vomiting (PONV) causes patient discomfort, lowers patient satisfaction, and increases care requirements. Opioid-induced nausea and vomiting (OINV) may also occur if opioids are used to treat postoperative pain. These guidelines aim to provide recommendations for the prevention and treatment of both problems. A working group was established in accordance with the charter of the Sociedad Española de Anestesiología y Reanimación. The group undertook the critical appraisal of articles relevant to the management of PONV and OINV in adults and children early and late in the perioperative period. Discussions led to recommendations, summarized as follows: 1) Risk for PONV should be assessed in all patients undergoing surgery; 2 easy-to-use scales are useful for risk assessment: the Apfel scale for adults and the Eberhart scale for children. 2) Measures to reduce baseline risk should be used for adults at moderate or high risk and all children. 3) Pharmacologic prophylaxis with 1 drug is useful for patients at low risk (Apfel or Eberhart 1) who are to receive general anesthesia; patients with higher levels of risk should receive prophylaxis with 2 or more drugs and baseline risk should be reduced (multimodal approach). 4) Dexamethasone, droperidol, and ondansetron (or other setrons) have similar levels of efficacy; drug choice should be made based on individual patient factors. 5) The drug prescribed for treating PONV should preferably be different from the one used for prophylaxis; ondansetron is the most effective drug for treating PONV. 6) Risk for PONV should be assessed before discharge after outpatient surgery or on the ward for hospitalized patients; there is no evidence that late preventive strategies are effective. 7) The drug of choice for preventing OINV is droperidol.

Operative anesthesia and pain control

A comprehensive understanding of operative anesthesia and postoperative pain control is essential to the practicing colon and rectal surgeon. Most of the operations performed-particularly in the perineum-cause significant patient discomfort and often result in a lengthy recovery period. A variety of factors, including patient positioning in the operating room and patient expectations, influence the choice of operative anesthesia. Postoperatively numerous modalities and agents exist for pain control. With this variety of options at hand, surgeons should be educated and decisions should be individualized, with the ultimate goals of improving the patient experience and facilitating recovery.

Long-lasting antinociceptive spinal effects in primates of the novel nociceptin/orphanin FQ receptor agonist UFP-112

Chemical modifications of nociceptin/orphanin FQ (N/OFQ) peptide that result in increased potency and resistance to degradation have recently lead to the discovery of [(pF)Phe(4)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-112), a novel N/OFQ peptide (NOP) receptor agonist. The aim of this study was to investigate the pharmacological profile of intrathecally administered UFP-112 in monkeys under different behavioral assays. Intrathecal UFP-112 (1-10 nmol) dose-dependently produced antinociception against an acute noxious stimulus (50 degrees C water) and capsaicin-induced thermal hyperalgesia. Intrathecal UFP-112-induced antinociception could be reversed by a NOP receptor antagonist, J-113397 (0.1mg/kg), but not by a classic opioid receptor antagonist, naltrexone (0.03 mg/kg). Like intrathecal morphine, UFP-112 produced antinociception in two primate pain models with a similar magnitude of effectiveness and a similar duration of action that last for 4-5h. Unlike intrathecal morphine, UFP-112 did not produce itch/scratching responses. In addition, intrathecal inactive doses of UFP-112 and morphine produced significant antinociceptive effects when given in combination without increasing scratching responses. These results demonstrated that intrathecal UFP-112 produced long-lasting morphine-comparable antinociceptive effects without potential itch side effect. This study is the first to provide functional evidence that selective NOP receptor agonists such as UFP-112 alone or in conjunction with morphine may improve the quality of spinal analgesia.

A randomized controlled trial of pentazocine versus ondansetron for the treatment of intrathecal morphine-induced pruritus in patients undergoing cesarean delivery

BACKGROUND

Ondansetron is effective for the treatment of intrathecal morphine-induced pruritus. There is evidence that kappa-opioid receptor agonists have antipruritic activity. Pentazocine is an agonist of kappa-opioid receptors and partial agonist at mu-opioid receptors. We therefore performed a randomized, double-blind trial to compare the efficacy of pentazocine and ondansetron for the treatment of pruritus associated with intrathecal injection of morphine in patients undergoing cesarean delivery.

METHODS

Two hundred eight parturients who developed moderate to severe pruritus after the administration of intrathecal morphine were randomly allocated to 2 groups: IV pentazocine 15 mg (n = 104) and IV ondansetron 4 mg (n = 104). The successful treatment of pruritus (no or mild pruritus) and other adverse effects were determined 15 min after study drug administration, and patients were observed for recurrence of pruritus for 4 h.

RESULTS

The treatment success rate at 15 min was higher in the pentazocine group (96.1%) than in the ondansetron group (80.8%) (95% confidence interval of difference: 7.0%, 23.8%; P = 0.001). The recurrence rate of moderate to severe pruritus within 4 h after treatment in the pentazocine group (12.0%) was lower than in the ondansetron group (32.1%) (P = 0.001). There were no significant differences between groups in nausea/vomiting, sedation, shivering, pain scores, and pain at injection site. No respiratory depression was observed.

CONCLUSIONS

Pentazocine 15 mg is superior to ondansetron 4 mg for the treatment of intrathecal morphine-induced pruritus and has a lower recurrence rate. The side effects after treatment are mild.