A Phase II Study About Efficacy and Safety of the Continuous IntraVenous Infusion of Ketamine as Adjuvant to Opioids in Terminally Ill Cancer Patients With Refractory Cancer Pain (CIVIK Trial)

BACKGROUND

Ketamine has been used to control refractory cancer pain as an adjuvant to opioids. We conducted a prospective phase II study to investigate the efficacy and safety of 5-day continuous intravenous infusion (CIVI) of Ketamine in terminally ill cancer patients with refractory cancer pain.

METHODS

Hospitalized terminally ill cancer patients with refractory cancer pain were enrolled. Refractory cancer pain was indicated by requirements for 4 or more rescue opioids or pain intensity using numerical rating scale > personalized pain goal (PPG) despite of intravenous morphine equivalent daily dose (IV MEDD) ≥ 120 mg/day. The CIVI of ketamine was increased from .05 mg/kg/hour to .5 mg/kg/hour by .05 every 8 hours if pain intensity exceeded PPG or if number of rescue opioids ≥2 during prior 8 hours was required. The primary end-point was overall pain response rate, which indicates complete response (both rescue opioid ≤3/day and pain intensity ≤ PPG) plus partial response (rescue opioid ≤3/day), without unacceptable toxicities.

RESULTS

Among 21 eligible patients enrolled between September 2019 and January 2023, 20 were analyzed. Most pain mechanisms were mixed type (n = 15, 75%), with neuropathic component (n = 17, 85%). The baseline background opioids were IV MEDD 186 mg/24hour (range, 124-592), number of rescue opioids was 6 (IQR, 5-9), and median PPG was 4 (IQR, 3-4). The overall pain response rate was 50% (n = 10) including 40% (n = 8) for complete pain response and 10% (n = 2) for partial pain response.

CONCLUSION

This study showed efficacy of gradually increasing CIVI of ketamine for terminally ill cancer patients with refractory cancer pain. CIVI of ketamine could be a useful tool in these patients considering the limited treatment options. (NCT03362073, Initial Release: November 15, 2017).

Practice Advisory for Postoperative Pain Management of Cardiac Surgical Patients: Executive Summary. A Report From the Society of Cardiovascular Anesthesiologists

Cardiac surgery is associated with significant postoperative pain that can affect patients' recovery and quality of life. Optimal analgesia after cardiac surgery can be challenging due to patients' coexisting morbidities and frequently observed adverse effects when opioids are used to treat postoperative pain. In this current era of enhanced recovery and fast track extubation, multimodal analgesia is increasingly being utilized for pain management after cardiac surgery. Regional analgesia is an integral part of multimodal analgesia and has garnered more attention since the development of fascial plane blocks. There is considerable variability among individuals, institutions, and practices in the analgesic approaches used to treat postoperative pain in cardiac surgical patients because of lack of consensus or guidelines. This practice advisory was developed with the overall goal of identifying opportunities for improving postoperative pain relief and pain-related outcomes after cardiac surgery and guiding perioperative providers through the provision of clinically relevant evidence-based recommendations.

Practice Advisory for Postoperative Pain Management of Thoracic Surgical Patients: Executive Summary: A Report by Society of Cardiovascular Anesthesiologists

Patients after thoracic surgery experience significant pain that can disrupt normal respiratory mechanics, increase the risk of respiratory complications, and impair recovery. Poorly controlled postoperative pain can develop into persistent postoperative pain. In addition, using opioids for pain control in the thoracic surgical population makes them more susceptible to opioid-related side effects due to their pre-existing comorbidities. The lack of consensus on how to effectively attain pain control in this surgical population has resulted in variability in the analgesic regimens utilized by providers across institutions and practices. The overall goal of this practice advisory is to identify opportunities for improvement in the postoperative pain management of thoracic surgical patients and provide guidance to perioperative providers through the provision of evidence-based recommendations.

Practice Advisory for Postoperative Pain Management of Thoracic Surgical Patients: A Report from the Society of Cardiovascular Anesthesiologists

Pain after thoracic surgery is often significant, which can disrupt normal respiratory mechanics and impair the clearance of secretions, thus increasing the risk of postoperative respiratory complications. Poorly controlled acute pain can lead to persistent post-thoracotomy pain and continued opioid use that can affect quality of life. With the increased awareness of opioid-associated adverse effects and recent emphasis on enhanced recovery, opioid-sparing multimodal analgesia has been used widely for acute pain management after thoracic surgery. This practice advisory reviews, evaluates, and summarizes the recent literature related to pharmacological therapies and non-pharmacological therapies used for postoperative pain management after thoracic surgery and offers guidance to providers in making appropriate pain management decisions for their patients.

The role of ketamine and its enantiomer in managing depression and pain in cancer patients: A narrative review

Depression and pain are common comorbidities in cancer patients, and ketamine, a dissociative anesthetic, has shown potential in managing both. This review summarizes current literature on ketamine and its enantiomer, esketamine, in managing depression and pain in the oncologic population. Studies indicate that sub-anesthetic doses of intravenous ketamine and esketamine can alleviate postoperative depressive symptoms in cancer patients with a tolerable safety profile. Research into non-intravenous routes for depression management in the oncologic population remains limited. Ketamine has also proven effective in managing acute postoperative pain, particularly through intravenous administration. While alternative administration routes, such as local infiltration and intramuscular methods, show mixed results, they may provide viable options for patients averse to intravenous (IV). However, the effectiveness of ketamine for chronic cancer pain remains inconsistent. Overall, ketamine offers a promising approach for managing depression and pain in oncologic patients.

Practice Advisory for Postoperative Pain Management of Cardiac Surgical Patients: A Report by Society of Cardiovascular Anesthesiologists

Moderate to severe pain after cardiac surgery is relatively common, which increases the risk of postoperative cardiopulmonary complications and delays hospital discharge. Opioids have been useful agents for postoperative pain control after cardiac surgery, but are associated with serious adverse effects. As a result, multimodal analgesia has been adopted widely to decrease reliance on opioids for treating postoperative pain, reduce opioid-related adverse effects, and promote early recovery. The advent of fascial plane blocks has expanded the use of regional analgesia for pain management after cardiac surgery that was otherwise limited due to the fear of devastating neurological sequelae in the setting of systemic anticoagulation. This practice advisory reviews and evaluates the recent literature related to the use of pharmacological and non-pharmacological therapies to treat pain after cardiac surgery to help providers with the selection of appropriate pain management interventions for their patients.

The Efficacy of Ketamine for Acute and Chronic Pain in Patients with Cancer: A Systematic Review of Randomized Controlled Trials

Managing cancer-related pain poses significant challenges, prompting research into alternative approaches such as ketamine. This systematic review aims to analyze and summarize the impact of ketamine as an adjuvant to opioid therapy for cancer-related pain. We conducted a literature review in MEDLINE, EMBASE, and Scopus from 1 January 1982 to 20 October 2023. Abstracts were screened against inclusion criteria, and eligible studies underwent a full-text review. Data was extracted from the included studies, and a framework analysis approach summarized the evidence regarding ketamine's use in patients with cancer. A total of 21 randomized clinical trials were included, and the quality of all the included studies was good or fair. Significant improvements in pain scores and reduced morphine consumption were consistently observed with intravenous ketamine administration for postoperative pain control, particularly when combined with other analgesics such as morphine. Ketamine was less effective when used as an analgesic for chronic pain management, with several studies on neuropathic pain or chemotherapy-induced neuropathy finding minimal significant effect on reduction of pain scores or morphine requirements. The efficacy of ketamine in pain management appears to depend on factors such as dosage, route of administration, and patient population.

The impact of ketamine on pain-related outcomes after thoracotomy: a systematic review with meta-analysis of randomized controlled trials

Objective

This meta-analysis aims to examine how effective ketamine is in the management of acute and preventing chronic post-thoracotomy pain by synthesizing the available research.

Method

A systematic literature search was conducted across PubMed, Scopus, and Cochrane Library till May 2023. Randomized Controlled Trials (RCT) examining the influence of ketamine on post-thoracotomy pain in adults were included. The intervention group included ketamine plus morphine, while the control group included morphine only. The outcome measures were opioid intake and pain scores at rest and on moving/coughing. Evidence quality was evaluated using the Cochrane Risk of Bias and GRADE assessment.

Results

Nine articles comprising 556 patients were selected for meta-analysis. The intervention group had a significant decrease in pain at rest (Std. Mean Difference (SMD = -0.60 with 95% CI [-0.83, -0.37]) and on movement/cough (SMD = -0.73 [-1.27, -0.18]) in the first postoperative days. Also, the ketamine group had lower opioid consumption (mg) in comparison with controls (SMD = -2.75 [-4.14, -1.36], p-value = 0.0001) in postoperative days 1-3. There was no data to assess the long-term effect of ketamine on chronic pain.

Conclusion

This meta-analysis shows that ketamine use can lower acute pain levels and morphine use after thoracotomy. In the future, larger RCTs using standardized methods and assessing both short-term and long-term analgesic effects of ketamine are necessary to deepen the understanding of the issue.

Ketamine in Critically Ill Patients: Use, Perceptions, and Potential Barriers

Objective: To evaluate practitioner use of ketamine and identify potential barriers to use in acutely and critically ill patients. To compare characteristics, beliefs, and practices of ketamine frequent users and non-users. Methods: An online survey developed by members of the Society of Critical Care Medicine (SCCM) Clinical Pharmacy and Pharmacology Section was distributed to physician, pharmacist, nurse practitioner, physician assistant and nurse members of SCCM. The online survey queried SCCM members on self-reported practices regarding ketamine use and potential barriers in acute and critically ill patients. Results: Respondents, 341 analyzed, were mostly adult physicians, practicing in the United States at academic medical centers. Clinicians were comfortable or very comfortable using ketamine to facilitate intubation (80.0%), for analgesia (77.9%), procedural sedation (79.4%), continuous ICU sedation (65.8%), dressing changes (62.4%), or for asthma exacerbation and status epilepticus (58.8% and 40.4%). Clinicians were least comfortable with ketamine use for alcohol withdrawal and opioid detoxification (24.7% and 23.2%). Most respondents reported "never" or "infrequently" using ketamine preferentially for continuous IV analgesia (55.6%) or sedation (61%). Responses were mixed across dosing ranges and duration. The most common barriers to ketamine use were adverse effects (42.6%), other practitioners not routinely using the medication (41.5%), lack of evidence (33.5%), lack of familiarity (33.1%), and hospital/institutional policy guiding the indication for use (32.3%). Conclusion: Although most critical care practitioners report feeling comfortable using ketamine, there are many inconsistencies in practice regarding dose, duration, and reasons to avoid or limit ketamine use. Further educational tools may be targeted at practitioners to improve appropriate ketamine use.

Historical Pathways for Opioid Addiction, Withdrawal with Traditional and Alternative Treatment Options with Ketamine, Cannabinoids, and Noribogaine: A Narrative Review

Even as prescription opioid dispensing rates have begun to decrease, the use of illicit opioids such as heroin and fentanyl has increased. Thus, the end of the opioid epidemic is not in sight, and treating patients that are addicted to opioids remains of utmost importance. Currently, the primary pharmacotherapies used to treat opioid addiction over the long term are the opioid antagonist naltrexone, the partial-agonist buprenorphine, and the full agonist methadone. Naloxone is an antagonist used to rapidly reverse opioid overdose. While these treatments are well-established and used regularly, the gravity of the opioid epidemic necessitates that all possible avenues of treatment be explored. Therefore, in this narrative review, we analyze current literature regarding use of the alternative medications ketamine, noribogaine, and cannabinoids in treating patients suffering from opioid use disorder. Beyond its use as an anesthetic, ketamine has been shown to have many applications in several medical specialties. Of particular interest to the subject at hand, ketamine is promising in treating individuals addicted to opioids, alcohol, and cocaine. Therapeutically administered cannabinoids have been proposed for the treatment of multiple illnesses. These include, but are not limited to epilepsy, Parkinson's disease, multiple sclerosis, chronic pain conditions, anxiety disorders, and addiction. The cannabinoid dronabinol has been seen to have varying effects. High doses appear to reduce withdrawal symptoms but this comes at the expense of increased adverse side effects such as sedation and tachycardia. Noribogaine is a weak MOR antagonist and relatively potent KOR agonist, which may explain the clinical anti-addictive effects. More research should be done to assess the viability of these medications for the treatment of OUD and withdrawal.

Regional anesthesia and acute perioperative pain management in thoracic surgery: a narrative review

Background and Objective

Thoracic surgery causes significant pain which can negatively affect pulmonary function and increase risk of postoperative complications. Effective analgesia is important to reduce splinting and atelectasis. Systemic opioids and thoracic epidural analgesia (TEA) have been used for decades and are effective at treating acute post-thoracotomy pain, although both have risks and adverse effects. The advancement of thoracoscopic surgery, a focus on multimodal and opioid-sparing analgesics, and the development of ultrasound-guided regional anesthesia techniques have greatly expanded the options for acute pain management after thoracic surgery. Despite the expansion of surgical techniques and analgesic approaches, there is no clear optimal approach to pain management. This review aims to summarize the body of literature regarding systemic and regional anesthetic techniques for thoracic surgery in both thoracotomy and minimally invasive approaches, with a goal of providing a foundation for providers to make individualized decisions for patients depending on surgical approach and patient factors, and to discuss avenues for future research.

Methods

We searched PubMed and Google Scholar databases from inception to May 2021 using the terms “thoracic surgery”, “thoracic surgery AND pain management”, “thoracic surgery AND analgesia”, “thoracic surgery AND regional anesthesia”, “thoracic surgery AND epidural”. We considered articles written in English and available to the reader.

Key Content and Findings

There is a wide variety of strategies for treating acute pain after thoracic surgery, including multimodal opioid and non-opioid systemic analgesics, regional anesthesia including TEA and paravertebral blocks (PVB), and a recent expansion in the use of novel fascial plane blocks especially for thoracoscopy. The body of literature on the effectiveness of different approaches for thoracotomy and thoracoscopy is a rapidly expanding field and area of active debate.

Conclusions

The optimal analgesic approach for thoracic surgery may depend on patient factors, surgical factors, and institutional factors. Although TEA may provide optimal analgesia after thoracotomy, PVB and emerging fascial plane blocks may offer effective alternatives. A tailored approach using multimodal systemic therapies and regional anesthesia is important, and future studies comparing techniques are necessary to further investigate the optimal approach to improve patient outcomes.

The effect of continuous intercostal nerve block vs. single shot on analgesic outcomes and hospital stays in minimally invasive direct coronary artery bypass surgery: a retrospective cohort study

BACKGROUND

Minimally invasive direct coronary artery bypass (MIDCAB) grafting surgery is accompanied by severe pain. Although continuous intercostal nerve block (CINB) has become one of the multimodal analgesic techniques in single port thoracoscopic surgery, its effects on MIDCAB are unclear. The purpose of this study was to compare the effects of CINB and single shot on analgesic outcomes and hospital stays in patients undergoing MIDCAB in a real-world setting.

METHODS

A retrospective cohort study was carried out at Peking University Third Hospital, China. Two hundred and sixteen patients undergoing MIDCAB were divided into two groups: a CINB group and a single block (SI) group. The primary outcome was postoperative maximal visual analog scale (VAS); secondary outcomes included the number of patients with maximal VAS ≤ 3, the demand for and consumed doses of pethidine and tramadol, and the length of intensive care unit (ICU) and hospital stays. The above data and the area under the VAS curve in the 70 h after extubation for the two subgroups (No. of grafts = 1) were also compared.

RESULTS

The maximum VAS was lower in the CINB group, and there were more cases with maximum VAS ≤ 3 in the CINB group: CINB 52 (40%) vs. SI 17 (20%), P = 0.002. The percentage of cases requiring tramadol and pethidine was less in CINB, P = 0.001. Among all patients, drug doses were significantly lower in the CINB group [tramadol: CINB 0 (0-100) mg vs. SI 100 (0-225) mg, P = 0.0001; pethidine: CINB 0 (0-25) mg vs. SI 25 (0-50) mg, P = 0.0004]. Further subgroup analysis showed that the area under the VAS curve in CINB was smaller: 28.05 in CINB vs. 30.41 in SI, P = 0.002. Finally, the length of ICU stay was shorter in CINB than in SI: 20.5 (11.3-26.0) h vs. 22.0 (19.0-45.0) h, P = 0.011.

CONCLUSIONS

CINB is associated with decreased demand for rescue analgesics and shorter length of ICU stay when compared to single shot intercostal nerve block. Additional randomized controlled trial (RCT) is needed to support these findings.

Safety of treatment options available for postoperative pain

IntroductionPostoperative pain is one of the most common adverse events after surgery and has been shown to increase the risk of other complications. On the other hand, liberal opioid use in the perioperative period is also associated with risk of adverse events. The current consensus is therefore to provide multimodal, opioid minimizing analgesia after surgery.Areas CoveredIn this review, we will discuss the benefits and risks associated with non-opioid analgesics, including non-steroidal anti-inflammatory drugs, gabapentinoids, ketamine, α-2 agonists, and corticosteroids. In addition, we will discuss the general and block-specific risks associated with regional anesthestic techniques.Expert OpinionAdverse events associated with non-opioid analgesics are rare outside their specific contraindicated patient groups, especially when dosed appropriately. α-2 agonists can cause transient hypotension and bradycardia, and gabapentinoids may cause sedation in higher risk patient populations. Regional anesthesia techniques are generally safe when done by an experienced practitioner. We therefore encourage the development of standardized multimodal analgesic protocols, which may facilitate opioid minimization and lead to better patient outcomes.

A Novel Application of Ketamine for Improving Perioperative Sleep Disturbances

Perioperative sleep disturbances are commonly observed before, during, and after surgery and can be caused by several factors, such as preoperative negative moods, general anesthetics, surgery trauma, and pain. Over the past decade, the fast-acting antidepressant effects of the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine represent one of the most attractive discoveries in the field of psychiatry, such as antidepressant and anxiolytic effects. It is also widely used as a short-acting anesthetic and analgesic. Recent research has revealed new possible applications for ketamine, such as for perioperative sleep disorders and circadian rhythm disorders. Here, we summarize the risk factors for perioperative sleep disturbances, outcomes of perioperative sleep disturbances, and mechanism of action of ketamine in improving perioperative sleep quality.

Overview of multimodal analgesia initiated in the perioperative setting

Despite progress in pain management in the perioperative setting, the literature is full of evidence that managing postoperative pain is suboptimal. Since the mechanism of pain is complex, the use of multimodal technique allows clinicians to use a combination of two or more drugs targeting different areas of pain transmission because of surgery. As part of enhanced recovery initiatives after surgery, healthcare and professional organisations incorporate the use of multimodal analgesia in surgical guidelines to improve patient satisfaction. This review aims to understand and summarise the current body of evidence involving the most common pharmacological therapies to manage postoperative pain in the preoperative setting.

The efficacy of ketamine for postoperative pain control in adolescent patients undergoing spinal fusion surgery for idiopathic scoliosis

The use of ketamine in conjunction with morphine to reduce postoperative pain has been explored in several different surgery subtypes with conflicting results. Ketamine has shown promise to have both opioid sparing and analgesic effects in the postoperative setting. This study aimed to elucidate ketamine's ability to reduce morphine equivalent consumption and improve patient satisfaction after spinal fusion surgery for the correction of idiopathic scoliosis. This surgery is known to be associated with significant postoperative pain which impedes the ability to improve patient satisfaction, and may complicate the recovery timeline. Currently, the standard therapeutic regimen consists of patient-controlled analgesia morphine and the use of other opioids such as hydromorphone. A prospective, randomized double-blinded, placebo-controlled trial was performed to compare the standard morphine equivalent therapy alone against a standard therapy in conjunction with ketamine. Fifty adolescent patients were enrolled and randomized. Results yielded a significant reduction in postoperative morphine equivalent consumption (p = 0.042), adjusted postoperative pain scores (p < 0.001), and incidence of nausea and vomiting (p = 0.045). The application of ketamine as an analgesic in conjunction with the current standard of morphine equivalent therapy may serve as a superior pain control regimen for spinal surgeries in young population. This regimen enhancement may be generalizable to other surgery subtypes within similar populations. LEVEL OF EVIDENCE: Level I.

Ketamine applications beyond anesthesia - A literature review

Ketamine's clinical use began in the 1970s. Physicians benefited from its safety and ability to induce short-term anesthesia and analgesia. The psychodysleptic effects caused by the drug called its further clinical use into question. Despite these unpleasant effects, ketamine is still applied in veterinary medicine, field medicine, and specialist anesthesia. Recent intensive research brought into light new possible applications of this drug. It began to be used in acute, chronic and cancer pain management. Most interesting reports come from research on the antidepressive and antisuicidal properties of ketamine giving hope for the creation of an effective treatment for major depressive disorder. Other reports highlight the possible use of ketamine in treating addiction, asthma and preventing cancer growth. Besides clinical use, the drug is also applied to in animal model of schizophrenia. It seems that nowadays, with numerous possible applications, the use of ketamine has returned; to its former glory. Nevertheless, the drug must be used with caution because still the mechanisms by which it executes its functions and long-term effects of its use are not fully known. This review aims to discuss the well-known and new promising applications of ketamine.

Analgesia and sedation post-coronary artery bypass graft surgery: a review of the literature

This review aimed to study the role of analgesia and sedation after coronary artery bypass graft (CABG) surgery, regarding pain management, assisted respiration, overall postoperative health care, and hospitalization. Data were collected from Pubmed, Scopus, and Cochrane databases. The following terms were used for the search: “analgesia”, “sedation”, “coronary artery bypass grafting”, CABG”, and “opioids”. Articles between the years 1988 and 2018 were evaluated. Several opioid and non-opioid analgesics used to relieve surgical pain are regarded as critical risk factors for developing pulmonary and cardiovascular complications in all kinds of thoracic surgery, especially CABG procedures. Effective pain management in post-CABG patients is largely dependent on effective pain assessment, type of sedatives and analgesics administered, and evaluation of their effects on pain relief. A significant challenge is to determine adequate amounts of administered analgesics and sedatives for postoperative CABG patients, because patients often order more sedatives and analgesics than needed. The pain management process is deemed successful when patients feel comfortable after surgery, with no negative side effects. However, postoperative pain management patterns have not included many modern methods such as patient-controlled analgesia, and postoperative pain management drugs are still limited to a restricted range of opioid and non-opioid analgesics.

Perioperative intravenous ketamine for acute postoperative pain in adults

BACKGROUND

Inadequate pain management after surgery increases the risk of postoperative complications and may predispose for chronic postsurgical pain. Perioperative ketamine may enhance conventional analgesics in the acute postoperative setting.

OBJECTIVES

To evaluate the efficacy and safety of perioperative intravenous ketamine in adult patients when used for the treatment or prevention of acute pain following general anaesthesia.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to July 2018 and three trials registers (metaRegister of controlled trials, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP)) together with reference checking, citation searching and contact with study authors to identify additional studies.

SELECTION CRITERIA

We sought randomised, double-blind, controlled trials of adults undergoing surgery under general anaesthesia and being treated with perioperative intravenous ketamine. Studies compared ketamine with placebo, or compared ketamine plus a basic analgesic, such as morphine or non-steroidal anti-inflammatory drug (NSAID), with a basic analgesic alone.

DATA COLLECTION AND ANALYSIS

Two review authors searched for studies, extracted efficacy and adverse event data, examined issues of study quality and potential bias, and performed analyses. Primary outcomes were opioid consumption and pain intensity at rest and during movement at 24 and 48 hours postoperatively. Secondary outcomes were time to first analgesic request, assessment of postoperative hyperalgesia, central nervous system (CNS) adverse effects, and postoperative nausea and vomiting. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included 130 studies with 8341 participants. Ketamine was given to 4588 participants and 3753 participants served as controls. Types of surgery included ear, nose or throat surgery, wisdom tooth extraction, thoracotomy, lumbar fusion surgery, microdiscectomy, hip joint replacement surgery, knee joint replacement surgery, anterior cruciate ligament repair, knee arthroscopy, mastectomy, haemorrhoidectomy, abdominal surgery, radical prostatectomy, thyroid surgery, elective caesarean section, and laparoscopic surgery. Racemic ketamine bolus doses were predominantly 0.25 mg to 1 mg, and infusions 2 to 5 µg/kg/minute; 10 studies used only S-ketamine and one only R-ketamine. Risk of bias was generally low or uncertain, except for study size; most had fewer than 50 participants per treatment arm, resulting in high heterogeneity, as expected, for most analyses. We did not stratify the main analysis by type of surgery or any other factor, such as dose or timing of ketamine administration, and used a non-stratified analysis.Perioperative intravenous ketamine reduced postoperative opioid consumption over 24 hours by 8 mg morphine equivalents (95% CI 6 to 9; 19% from 42 mg consumed by participants given placebo, moderate-quality evidence; 65 studies, 4004 participants). Over 48 hours, opioid consumption was 13 mg lower (95% CI 10 to 15; 19% from 67 mg with placebo, moderate-quality evidence; 37 studies, 2449 participants).Perioperative intravenous ketamine reduced pain at rest at 24 hours by 5/100 mm on a visual analogue scale (95% CI 4 to 7; 19% lower from 26/100 mm with placebo, high-quality evidence; 82 studies, 5004 participants), and at 48 hours by 5/100 mm (95% CI 3 to 7; 22% lower from 23/100 mm, high-quality evidence; 49 studies, 2962 participants). Pain during movement was reduced at 24 hours (6/100 mm, 14% lower from 42/100 mm, moderate-quality evidence; 29 studies, 1806 participants), and 48 hours (6/100 mm, 16% lower from 37 mm, low-quality evidence; 23 studies, 1353 participants).Results for primary outcomes were consistent when analysed by pain at rest or on movement, operation type, and timing of administration, or sensitivity to study size and pain intensity. No analysis by dose was possible. There was no difference when nitrous oxide was used. We downgraded the quality of the evidence once if numbers of participants were large but small-study effects were present, or twice if numbers were small and small-study effects likely but testing not possible.Ketamine increased the time for the first postoperative analgesic request by 54 minutes (95% CI 37 to 71 minutes), from a mean of 39 minutes with placebo (moderate-quality evidence; 31 studies, 1678 participants). Ketamine reduced the area of postoperative hyperalgesia by 7 cm² (95% CI -11.9 to -2.2), compared with placebo (very low-quality evidence; 7 studies 333 participants). We downgraded the quality of evidence because of small-study effects or because the number of participants was below 400.CNS adverse events occurred in 52 studies, while 53 studies reported of absence of CNS adverse events. Overall, 187/3614 (5%) participants receiving ketamine and 122/2924 (4%) receiving control treatment experienced an adverse event (RR 1.2, 95% CI 0.95 to 1.4; high-quality evidence; 105 studies, 6538 participants). Ketamine reduced postoperative nausea and vomiting from 27% with placebo to 23% with ketamine (RR 0.88, 95% CI 0.81 to 0.96; the number needed to treat to prevent one episode of postoperative nausea and vomiting with perioperative intravenous ketamine administration was 24 (95% CI 16 to 54; high-quality evidence; 95 studies, 5965 participants).

AUTHORS' CONCLUSIONS

Perioperative intravenous ketamine probably reduces postoperative analgesic consumption and pain intensity. Results were consistent in different operation types or timing of ketamine administration, with larger and smaller studies, and by higher and lower pain intensity. CNS adverse events were little different with ketamine or control. Perioperative intravenous ketamine probably reduces postoperative nausea and vomiting by a small extent, of arguable clinical relevance.

Persistent Postsurgical Pain

The development of chronic pain is considered a major complication after surgery. Basic science research in animal models helps us understand the transition from acute to chronic pain by identifying the numerous molecular and cellular changes that occur in the peripheral and central nervous systems. It is now well recognized that inflammation and nerve injury lead to long-term synaptic plasticity that amplifies and also maintains pain signaling, a phenomenon referred to as pain sensitization. In the context of surgery in humans, pain sensitization is both responsible for an increase in postoperative pain via the expression of wound hyperalgesia and considered a critical factor for the development of persistent postsurgical pain. Using specific drugs that block the processes of pain sensitization reduces postoperative pain and prevents the development of persistent postoperative pain. This narrative review of the literature describes clinical investigations evaluating different preventative pharmacologic strategies that are routinely used by anesthesiologists in their daily clinical practices for preventing persistent postoperative pain. Nevertheless, further efforts are needed in both basic and clinical science research to identify preclinical models and novel therapeutics targets. There remains a need for more patient numbers in clinical research, for more reliable data, and for the development of the safest and the most effective strategies to limit the incidence of persistent postoperative pain.

Consensus Guidelines on the Use of Intravenous Ketamine Infusions for Acute Pain Management From the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, and the American Society of Anesthesiologists

BACKGROUND

Ketamine infusions have been used for decades to treat acute pain, but a recent surge in usage has made the infusions a mainstay of treatment in emergency departments, in the perioperative period in individuals with refractory pain, and in opioid-tolerant patients. The widespread variability in patient selection, treatment parameters, and monitoring indicates a need for the creation of consensus guidelines.

METHODS

The development of acute pain ketamine guidelines grew as a corollary from the genesis of chronic pain ketamine guidelines. The charge for the development of acute pain ketamine guidelines was provided by the Boards of Directors of both the American Society of Regional Anesthesia and Pain Medicine and the American Academy of Pain Medicine, who approved the document along with the American Society of Anesthesiologists' Committees on Pain Medicine and Standards and Practice Parameters. The committee chair developed questions based on input from the committee during conference calls, which the committee then refined. Groups of 3 to 5 panel members and the committee chair were responsible for answering individual questions. After preliminary consensus was achieved, the entire committee made further revisions via e-mail and conference calls.

RESULTS

Consensus guidelines were prepared in the following areas: indications, contraindications for acute pain and whether they differ from those for chronic pain, the evidence for the use of ketamine as an adjunct to opioid-based therapy, the evidence supporting patient-controlled ketamine analgesia, the use of nonparenteral forms of ketamine, and the subanesthetic dosage range and whether the evidence supports those dosages for acute pain. The group was able to reach consensus on the answers to all questions.

CONCLUSIONS

Evidence supports the use of ketamine for acute pain in a variety of contexts, including as a stand-alone treatment, as an adjunct to opioids, and, to a lesser extent, as an intranasal formulation. Contraindications for acute pain are similar to those for chronic pain, partly based on the observation that the dosage ranges are similar. Larger studies evaluating different acute pain conditions are needed to enhance patient selection, determine the effectiveness of nonparenteral ketamine alternatives, define optimal treatment parameters, and develop protocols optimizing safety and access to care.

Low-dose intravenous ketamine for postcardiac surgery pain: Effect on opioid consumption and the incidence of chronic pain

BACKGROUND

Recent meta-analyses have concluded that low-dose intravenous ketamine infusions (LDKIs) during the postoperative period may help to decrease acute and chronic postoperative pain after major surgery.

AIMS

This study aims to evaluate the level of pain at least 3 months after surgery for patients treated with a postoperative LDKI versus patients who were not treated with a postoperative LDKI.

METHODS

Administrative and Ethics Board approval were obtained for this study. We performed a retrospective chart review for all patients receiving LDKI, and equal number of age-, sex-, and surgery-matched patients who did not receive LDKI. Low-dose ketamine was prepared using 100 mg of ketamine in 100 ml of normal saline and run between 50 and 200 mcg/kg/h.

RESULTS

We reviewed 115 patients with LDKI and 115 without LDKI. The average age was 63.1 years, 73% of the patients were men and sex was evenly distributed between LDKI and non-LDKI. The average duration of the ketamine infusions was 26.8 h with the average dose being 169.9 mg. At an average of 9 months after surgery, 42% of the ketamine group and 38% of the nonketamine group stated that they had had pain on discharge. Of these patients, 30% of the ketamine group and 26% of the nonketamine group still had pain at the time of the phone call. Women in both groups had more acute and chronic pain than men.

CONCLUSION

These results show that LDKI does not promote a decrease in long-term postoperative pain.

Ketamine versus hydromorphone patient-controlled analgesia for acute pain in trauma patients

BACKGROUND

It is unknown whether ketamine administered via patient-controlled analgesia (PCA) provides adequate analgesia while reducing opioid consumption in the traumatically injured patient. Differences in opioid consumption, pain scores, and adverse effects between ketamine and hydromorphone PCA were studied.

MATERIALS AND METHODS

This is an investigator-initiated, single-center, double-blinded, randomized, pilot trial conducted from 2014 to 2016 at a level 1 trauma center. Nonintubated trauma patients in intensive care, who were receiving PCA, were randomized to ketamine or hydromorphone PCA plus opioid analgesics for breakthrough pain.

RESULTS

Twenty subjects were randomized. There was no difference in median daily breakthrough opioid use (10 [0.63-19.38] mg versus 10 [4.38-22.5] mg, P = 0.55). Subjects in the ketamine group had lower median cumulative opioid use on therapy day 1 than the hydromorphone group (4.6 [2.5-15] mg versus 41.8 [31.8-50] mg, P < 0.001), as well as in the first 48 h (10 [3.3-15] mg versus 48.5 [32.1-67.5] mg, P < 0.001) and first 72 h (10 [4.2-15] mg versus 42.5 [31.7-65.2] mg, P < 0.001) of therapy. Daily oxygen supplementation requirements were lower in the ketamine group (0.5 [0-1.5] L/min versus 2 [0.5-3] L/min, P = 0.020). Hallucinations occurred more frequently in the ketamine group (40% versus 0%, P = 0.090).

CONCLUSIONS

Ketamine PCA led to lower cumulative opioid consumption and lower oxygen supplementation requirements, though hallucinations occurred more frequently with use of ketamine. Additional studies are needed to investigate the tolerability of ketamine as an alternative to traditional opioid-based PCA.

Benefit and harm of adding ketamine to an opioid in a patient-controlled analgesia device for the control of postoperative pain: systematic review and meta-analyses of randomized controlled trials with trial sequential analyses

Ketamine is often added to opioids in patient-controlled analgesia devices. We tested whether in surgical patients, ketamine added to an opioid patient-controlled analgesia decreased pain intensity by ≥25%, cumulative opioid consumption by ≥30%, the risk of postoperative nausea and vomiting by ≥30%, the risk of respiratory adverse effects by ≥50%, and increased the risk of hallucination not more than 2-fold. In addition, we searched for evidence of dose-responsiveness. Nineteen randomized trials (1349 adults, 104 children) testing different ketamine regimens added to various opioids were identified through searches in databases and bibliographies (to 04.2016). In 9 trials (595 patients), pain intensity at rest at 24 hours was decreased by 32% with ketamine (weighted mean difference -1.1 cm on the 0-10 cm visual analog scale [98% CI, -1.8 to -0.39], P < 0.001). In 7 trials (495 patients), cumulative 24 hours morphine consumption was decreased by 28% with ketamine (weighted mean difference -12.9 mg [-22.4 to -3.35], P = 0.002). In 7 trials (435 patients), the incidence of postoperative nausea and vomiting was decreased by 44% with ketamine (risk ratio 0.56 [0.40 to 0.78], P < 0.001). There was no evidence of a difference in the incidence of respiratory adverse events (9 trials, 871 patients; risk ratio 0.31 [0.06 to 1.51], P = 0.08) or hallucination (7 trials, 690 patients; odds ratio 1.16 [0.47 to 2.79], P = 0.70). Trial sequential analyses confirmed the significant benefit of ketamine on pain intensity, cumulative morphine consumption, and postoperative nausea and vomiting and its inability to double the risk of hallucination. The available data did not allow us to make a conclusion on respiratory adverse events or to establish dose-responsiveness.

Subdissociative intranasal ketamine plus standard pain therapy versus standard pain therapy in the treatment of paediatric sickle cell disease vaso-occlusive crises in resource-limited settings: study protocol for a randomised controlled trial

INTRODUCTION

Pediatric sickle cell disease, highly prevalent in sub-Saharan Africa, carries great morbidity and mortality risk. Limited resources and monitoring make management of acute vaso-occlusive crises challenging. This study aims to evaluate the efficacy and safety of subdissociative intranasal ketamine as a cheap, readily available and easily administered adjunct to standard pain therapy. We hypothesise that subdissociative, intranasal ketamine may significantly augment current approaches to pain management in resource-limited settings in a safe and cost-effective manner.

METHODS AND ANALYSIS

This is a multicentred, randomised, double-blind, placebo-controlled trial enrolling children 4-16 years of age with sickle cell disease and painful vaso-occlusive pain crises. Study sites include two sub-Saharan teaching and referral hospitals with acute intake areas. All patients receive standard analgesic therapy during evaluation. Patients randomised to the treatment arm receive 1 mg/kg intranasal ketamine at onset of therapy, while placebo arm participants receive volume-matched intranasal normal saline. All participants and clinical staff are blinded to the treatment allocation. Data will be analysed on an intention-to-treat basis. Primary endpoints are changes in self-report pain scales (Faces Pain Scale-Revised) at 30, 60 and 120 minutes and rates of adverse events. Secondary endpoints include hospital length of stay, total analgesia use and quality of life assessment 2-3 weeks postintervention.

ETHICS AND DISSEMINATION

The research methods for this study have been approved by the Cameroon Baptist Convention Health Board Institutional Review Board (IRB2015-07), the Tanzanian National Institute for Medical Research (NIMR/HQ/R.8a/Vol. IX/2299), Muhimbili National Hospital IRB (MNH/IRB/I/2015/14) and the Tanzanian Food and Drugs Authority (TFDA0015/CTR/0015/9). Data reports will be provided to the Data and Safety Monitoring Board (DSMB) periodically throughout the study as well as all reports of adverse events. All protocol amendments will also be reviewed by the DSMB. Study results, regardless of direction or amplitude, will be submitted for publication in relevant peer-reviewed journals.

TRIAL REGISTRATION

ClinicalTrials.Gov, NCT02573714. Date of registration: 8 October 2015. Pre-results.

Perioperative pregabalin for reducing pain, analgesic consumption, and anxiety and enhancing sleep quality in elective neurosurgical patients: a prospective, randomized, double-blind, and controlled clinical study

OBJECTIVE

The aim of this study was to assess in-hospital (immediate) postoperative pain scores and analgesic consumption (primary goals) and preoperative anxiety and sleep quality (secondary goals) in patients who underwent craniotomy and were treated with pregabalin (PGL). Whenever possible, out-of-hospital pain scores and analgesics usage data were obtained as well.

METHODS

This prospective, randomized, double-blind and controlled study was conducted in consenting patients who underwent elective craniotomy for brain tumor resection at Tel Aviv Medical Center between 2012 and 2014. Patients received either 150 mg PGL (n = 50) or 500 mg starch (placebo; n = 50) on the evening before surgery, 1.5 hours before surgery, and twice daily for 72 hours following surgery. All patients spent the night before surgery in the hospital, and no other premedication was administered. Opioids and nonsteroidal antiinflammatory drugs were used for pain, which was self-rated by means of a numerical rating scale (score range 0–10).

RESULTS

Eighty-eight patients completed the study. Data on the American Society of Anesthesiologists class, age, body weight, duration of surgery, and intraoperative drugs were similar for both groups. The pain scores during postoperative Days 0 to 2 were significantly lower in the PGL group than in the placebo group (p < 0.01). Analgesic consumption was also lower in the PGL group, both immediately and 1 month after surgery. There were fewer requests for antiemetics in the PGL group, and the rate of postoperative nausea and vomiting was lower. The preoperative anxiety level and the quality of sleep were significantly better in the PGL group (p < 0.01). There were no PGL-associated major adverse events.

CONCLUSIONS

Perioperative use of twice-daily 150 mg pregabalin attenuates preoperative anxiety, improves sleep quality, and reduces postoperative pain scores and analgesic usage without increasing the rate of adverse effects.

Clinical trial registration no.: NCT01612832 (clinicaltrials.gov)

Ketamine: 50 Years of Modulating the Mind

Ketamine was introduced into clinical practice in the 1960s and continues to be both clinically useful and scientifically fascinating. With considerably diverse molecular targets and neurophysiological properties, ketamine’s effects on the central nervous system remain incompletely understood. Investigators have leveraged the unique characteristics of ketamine to explore the invariant, fundamental mechanisms of anesthetic action. Emerging evidence indicates that ketamine-mediated anesthesia may occur via disruption of corticocortical information transfer in a frontal-to-parietal (“top down”) distribution. This proposed mechanism of general anesthesia has since been demonstrated with anesthetics in other pharmacological classes as well. Ketamine remains invaluable to the fields of anesthesiology and critical care medicine, in large part due to its ability to maintain cardiorespiratory stability while providing effective sedation and analgesia. Furthermore, there may be an emerging role for ketamine in treatment of refractory depression and Post-Traumatic Stress Disorder. In this article, we review the history of ketamine, its pharmacology, putative mechanisms of action and current clinical applications.

Pathophysiology, assessment, and management of pain in critically ill adults

PURPOSE

The pathophysiology of pain in critically ill patients, the role of pain assessment in optimal pain management, and pharmacologic and nonpharmacologic strategies for pain prevention and treatment are reviewed.

SUMMARY

There are many short- and long-term consequences of inadequately treated pain, including hyperglycemia, insulin resistance, an increased risk of infection, decreased patient comfort and satisfaction, and the development of chronic pain. Clinicians should have an understanding of the basic physiology of pain and the patient populations that are affected. Pain should be assessed using validated pain scales that are appropriate for the patient's communication status. Opioids are the cornerstone of pain treatment. The use of opioids, administered via bolus dosing or continuous infusion, should be guided by patient-specific goals of care in order to avoid adverse events. A multimodal approach to pain management, including the use of regional analgesia, may improve patient outcomes and decrease opioid-related adverse events, though there are limited relevant data in adult critically ill patient populations. Nonpharmacologic strategies have been shown to be effective adjuncts to pharmacologic regimens that can improve patient-reported pain intensity and reduce analgesic requirements. Analgesic regimens need to take into account patient-specific factors and be closely monitored for safety and efficacy.

CONCLUSION

Acute pain management in the critically ill is a largely underassessed and undertreated area of critical care. Opioids are the cornerstone of treatment, though a multimodal approach may improve patient outcomes and decrease opioid-related adverse events.

Ketamine coadministration attenuates morphine tolerance and leads to increased brain concentrations of both drugs in the rat

Background and Purpose

The effects of ketamine in attenuating morphine tolerance have been suggested to result from a pharmacodynamic interaction. We studied whether ketamine might increase brain morphine concentrations in acute coadministration, in morphine tolerance and morphine withdrawal.

Experimental Approach

Morphine minipumps (6 mg·day^–1) induced tolerance during 5 days in Sprague–Dawley rats, after which s.c. ketamine (10 mg·kg^–1) was administered. Tail flick, hot plate and rotarod tests were used for behavioural testing. Serum levels and whole tissue brain and liver concentrations of morphine, morphine-3-glucuronide, ketamine and norketamine were measured using HPLC-tandem mass spectrometry.

Key Results

In morphine-naïve rats, ketamine caused no antinociception whereas in morphine-tolerant rats there was significant antinociception (57% maximum possible effect in the tail flick test 90 min after administration) lasting up to 150 min. In the brain of morphine-tolerant ketamine-treated rats, the morphine, ketamine and norketamine concentrations were 2.1-, 1.4- and 3.4-fold, respectively, compared with the rats treated with morphine or ketamine only. In the liver of morphine-tolerant ketamine-treated rats, ketamine concentration was sixfold compared with morphine-naïve rats. After a 2 day morphine withdrawal period, smaller but parallel concentration changes were observed. In acute coadministration, ketamine increased the brain morphine concentration by 20%, but no increase in ketamine concentrations or increased antinociception was observed.

Conclusions and Implications

The ability of ketamine to induce antinociception in rats made tolerant to morphine may also be due to increased brain concentrations of morphine, ketamine and norketamine. The relevance of these findings needs to be assessed in humans.

Effect of preemptive intra-articular morphine and ketamine on pain after arthroscopic rotator cuff repair: a prospective, double-blind, randomized controlled study

BACKGROUND

Rotator cuff tear is a leading etiology of shoulder pain and disability. Surgical treatment is indicated in patients with persistent pain who fail a trial of non-surgical treatment. Pain reduction following rotator cuff repair, particularly within the first 24-48 h, is a major concern to both doctors and patients. This study aimed to compare the postoperative antinociceptive additive effects of pre-incisional intra-articular (IA) ketamine when combined with morphine with two times the dose of morphine or saline.

METHODS

In this prospective, randomized, double blind, controlled trial patients undergoing arthroscopic rotator cuff tear repair (ARCR) under general anesthesia were enrolled. Patients were randomly assigned to one of the three intervention groups. Twenty minutes prior to incision, morphine (20 mg/10 ml), ketamine (50 mg + morphine 10 mg/10 ml), or saline (0.9 % 10 ml) (n = 15/group), were administered to all patients. First 24 h postoperative analgesia consisted of intravenous patient controlled analgesia (IV-PCA) morphine and oral rescue paracetamol 1000 mg or oxycodone 5 mg. 24-h, 2-week and 3-month patient rated pain numeric rating scale (NRS) and analgesics consumption were documented.

RESULTS

Patients' demographic and perioperative data were similar among all groups. The 24-h and the 2-week NRSs were significantly (p < 0.05) lower in both treatment groups compared to placebo, but were not significantly different between the two intervention groups. PCA-morphine and oral analgesics were consumed similarly among the groups throughout the study phases.

CONCLUSIONS

Pre-incisional intra-articular morphine reduced pain in the first 2 weeks after arthroscopic rotator cuff repair. Further research is warranted to elucidate the optimal timing and dosing of IA ketamine and morphine for postoperative analgesic effects.

Effect of intraoperative infusion of low-dose ketamine on management of postoperative analgesia

Background:

Use of opioids for perioperative analgesia is associated with sedation, respiratory depression and postoperative nausea and vomiting. N-methyl-D-aspartate receptor antagonist such as ketamine has both analgesic and antihyperalgesic properties. We studied the effect of intraoperative infusion of low-dose ketamine on postoperative analgesia and its management with opioids.

Materials and Methods:

A total of 80 patients scheduled for open cholecystectomy under general anesthesia were randomly allocated into two equal groups in a randomized double-blinded way. The general anesthetic technique was standardized in both groups. Group K patients (n = 40) received bolus of ketamine 0.2 mg/kg intravenously followed by an infusion of 0.1 mg/kg/h before skin incision, which was continued up to the end of surgery. Similar volume of saline was infused in Group C (n = 40). The pain score at different intervals and cumulative morphine consumption over 24 h was observed. Secondary outcomes such as hemodynamic parameters, patient satisfaction score and incidences of side effects were also recorded.

Results:

Intraoperative infusion of low-dose ketamine resulted in effective analgesia in first 6 h of the postoperative period, which was evident from reduced pain scores and reduced opioid requirements (P = 0.001). The incidence of side effects and patient satisfaction were similar in both groups.

Conclusion:

Intraoperative low-dose ketamine infusion provides good postoperative analgesia while reducing need of opioid analgesics, which must be considered for better management of postoperative analgesia.

Continuous Infusion of Ketamine for Out-of-hospital Isolated Orthopedic Injuries Secondary to Trauma: A Randomized Controlled Trial

Abstract Objective. Although ketamine has recently been demonstrated to provide a morphine-sparing effect, no previous study reports the effect of continuous infusion of ketamine for analgesia in out-of-hospital environments. The aim of this study was to compare the effect of a continuous infusion of ketamine (IK group) vs. a continuous infusion of saline (IS group) on morphine requirements in out-of-hospital trauma patients suffering from severe acute pain. Methods. In this prospective, multicenter, randomized, single-blind clinical study, patients suffering from isolated orthopedic injuries secondary to trauma with severe acute pain received a low-dose intravenous (IV) bolus of ketamine (0.2 mg·kg^-1) combined with an IV bolus of morphine (0.1 mg·kg^-1) and were randomized either in the IK group (IV continuous infusion of ketamine 0.2 mg·kg^-1·h^-1), or in the IS group (IV continuous infusion of saline at the same volume). The primary endpoint was morphine requirements in terms of total dose of morphine (excluding the baseline bolus) injected at the end of prehospital emergency care at hospital admission (final time, Tf). The secondary endpoint was evaluation of pain with visual analogic scale (VAS). Results. Sixty-six patients were enrolled. Total morphine dose was not significantly reduced with continuous infusion of ketamine (0.048 [0.000; 0.150] vs. 0.107 [0.052; 0.150] in IK and IS groups), with similar mean duration of care (median 35.0 min). Analgesia was as efficient without any significant difference in VAS at Tf between groups (3.1 ± 2.3 (IK group) vs. 3.7 ± 2.7 (IS group), p = 0.5). Conclusions. Continuous ketamine infusion did not reduce morphine requirements in severe acute pain trauma patients in the out-of-hospital emergency settings.

Evaluation the effects of adding ketamine to morphine in intravenous patient-controlled analgesia after orthopedic surgery

Background:

Intravenous patient-controlled analgesia (PCA) with morphine is commonly used for post-operative pain after major surgery. Ketamine has analgesic property at lower doses, and in combination with opioids it could have synergistic effect. The aim of this study is to determine effects of the addition of ketamine to morphine for PCA after orthopedic surgery.

Materials and Methods:

In this double-blind randomized clinical trial, 60 patients were randomly allocated to receive PCA consisting: Group 1 (morphine 0.2 mg/ml), Group 2 (morphine 0.2 mg/ml + ketamine 1 mg/ml), and Group 3 (morphine 0.1 mg/ml + ketamine 2 mg/ml). In this, anesthesiologists managed study, patients had orthopedic surgery. Assessments were made at 24 h and 48 h post-operatively. Visual analog scale (VAS) was used for recording pain score. PCA morphine use was recorded at 24 h and 48 h. VAS scores over 48 h were analyzed with analysis of variance for repeated measures. Significance level was taken as 0.05.

Results:

There is no significant difference between demographic information of the three groups (P > 0.05). Control of pain in Group 2 and Group 3 was better than in Group 1 (only morphine) (P = 0.001) but there was no significant difference between Group 2 and Group 3 (P > 0.05). Rate of narcotic consumption in groups 2 and 3 was significantly lower than Group 1 (P < 0.05).

Conclusion:

After orthopedic surgery, the addition of ketamine to morphine for intravenous PCA was superior to Intravenous PCA opioid alone. The combination induces a significant reduction in pain score and cumulative morphine consumption.

Study of patient pain management after heart surgery

PURPOSE

To investigate postoperative pain control and analgesic use after heart surgery.

METHODS

20 patients undergone heart surgery, randomly entered the study. Each patient was asked to score his pain intensity on visual analog scale (VAS) at four different occasions.

RESULTS

120 patients aged 59 year-old; including 81 male were enrolled in the study. 69.2% had coronary artery disease and 16.7% had heart-valve problem. Main types of surgeries were coronary artery bypass surgery (70.5%) and valve repairement (23%). Duration of ICU stay was 4.78±2.7 days and duration of intubations was 17.38 ± 36.46 hours. Pre-surgery pain relief was administrated to 42% of the subjects and morphine and promethazine was the main pre-surgery analgesia medication. Post surgery analgesic included morphine (injection), petidine (injection) and NSAIDS (oral or rectal). According to VAS, mean pain level, 1 and 4 hours after extubation, and before and one hour after transferring to wards was 5.05±2.5, 4.09±2.0, 3.52±1.8, 2.36±1.89, respectively. Although the level of pain reported was mostly moderate, 80% were reported satisfaction with their post-surgery pain management.

CONCLUSION

A closer pain management control is needed for patients after heart surgery. Introduction of newer pain management techniques, medications and dosages could reduce the pain and suffering.

Pharmacotherapy for the prevention of chronic pain after surgery in adults

BACKGROUND

Chronic pain can often occur after surgery, substantially impairing patients' health and quality of life. It is caused by complex mechanisms that are not yet well understood. The predictable nature of most surgical procedures has allowed for the conduct of randomized controlled trials of pharmacological interventions aimed at preventing chronic postsurgical pain.

OBJECTIVES

The primary objective was to evaluate the efficacy of systemic drugs for the prevention of chronic pain after surgery by examining the proportion of patients reporting pain three months or more after surgery. The secondary objective was to evaluate the safety of drugs administered for the prevention of chronic pain after surgery.

SEARCH METHODS

We identified randomized controlled trials (RCTs) of various systemically administered drugs for the prevention of chronic pain after surgery from CENTRAL, MEDLINE, EMBASE and handsearches of other reviews and trial registries. The most recent search was performed on 17 July 2013.  

SELECTION CRITERIA

Included studies were double-blind, placebo-controlled, randomized trials involving adults and evaluating one or more drugs administered systemically before, during or after surgery, or both, which measured pain three months or more after surgery.

DATA COLLECTION AND ANALYSIS

Data collected from each study included the study drug name, dose, route, timing and duration of dosing; surgical procedure; proportion of patients reporting any pain three months or more after surgery, reporting at least 4/10 or moderate to severe pain three months or more after surgery; and proportion of participants dropping out of the study due to treatment-emergent adverse effects.

MAIN RESULTS

We identified 40 RCTs of various pharmacological interventions including intravenous ketamine (14 RCTs), oral gabapentin (10 RCTs), oral pregabalin (5 RCTs), non-steroidal anti-inflammatories (3 RCTs), intravenous steroids (3 RCTs), oral N-methyl-D-aspartate (NMDA) blockers (3 RCTs), oral mexiletine (2 RCTs), intravenous fentanyl (1 RCT), intravenous lidocaine (1 RCT), oral venlafaxine (1 RCT) and inhaled nitrous oxide (1 RCT). Meta-analysis suggested a modest but statistically significant reduction in the incidence of chronic pain after surgery following treatment with ketamine but not gabapentin or pregabalin. Results with ketamine should be viewed with caution since most of the included trials were small (that is < 100 participants per treatment arm), which could lead to the overestimation of treatment effect.

AUTHORS' CONCLUSIONS

Additional evidence from better, well designed, large-scale trials is needed in order to more rigorously evaluate pharmacological interventions for the prevention of chronic pain after surgery. Furthermore, available evidence does not support the efficacy of gabapentin, pregabalin, non-steroidal anti-inflammatories, intravenous steroids, oral NMDA blockers, oral mexiletine, intravenous fentanyl, intravenous lidocaine, oral venlafaxine or inhaled nitrous oxide for the prevention of chronic postoperative pain.

Perioperative interventions to reduce chronic postsurgical pain

Approximately 10% of patients following a variety of surgeries develop chronic postsurgical pain. Reducing chronic postoperative pain is especially important to reconstructive surgeons because common operations such as breast and limb reconstruction have even higher risk for developing chronic postsurgical pain. Animal studies of posttraumatic nerve injury pain demonstrate that there is a critical time frame before and immediately after nerve injury in which specific interventions can reduce the incidence and intensity of chronic neuropathic pain behaviors-so called "preventative analgesia." In animal models, perineural local anesthetic, systemic intravenous local anesthetic, perineural clonidine, systemic gabapentin, systemic tricyclic antidepressants, and minocycline have each been shown to reduce pain behaviors days to weeks after treatment. The translation of this work to humans also suggests that brief perioperative interventions may protect patients from developing new chronic postsurgical pain. Recent clinical trial data show that there is an opportunity during the perioperative period to dramatically reduce the incidence and severity of chronic postsurgical pain. The surgeon, working with the anesthesiologist, has the ability to modify both early and chronic postoperative pain by implementing an evidence-based preventative analgesia plan.

Can Gradual Dose Titration of Ketamine for Management of Neuropathic Pain Prevent Psychotomimetic Effects in Patients With Advanced Cancer?

Background:

Ketamine is often used to manage neuropathic pain in patients with cancer. However, it occasionally causes psychotomimetic effects such as vivid dreams, nightmares, illusions, hallucinations, and altered body image. Objective: To examine whether gradual dose titration of ketamine for management of neuropathic pain prevents psychotomimetic effects in patients with advanced cancer.

Methods:

This was a retrospective chart review. We administered ketamine when neuropathic pain in patients with advanced cancer became refractory to opioids and oral adjuvant analgesics. The starting dose of ketamine was 10 mg/d by continuous intravenous infusion. The dose was gradually increased by 10 mg/d every 4 to 6 hours to 50 mg/d or until the pain was relieved. It was subsequently increased by 25 mg/d every 12 to 24 hours until the pain was relieved.

Results:

For this study, we enrolled 46 patients with advanced cancer. The mean age was 52.2 ± 16.9 years. The mean dose at onset of action and maximum dose of ketamine were 56 ± 58 and 272 ± 214 mg/d, respectively. The mean pain intensity (numerical rating scale) decreased significantly from 7.3 ± 2.0 to 3.5 ± 2.2 after the administration of ketamine ( P < .01). The effectiveness was 69.5%. No psychotomimetic effect of less than 300 mg/d was observed during the introduction phase even though psychotropic drugs were not prescribed. Mild sedation was observed in 3 patients (7%) as the only adverse effect during the introduction phase.

Conclusion:

Gradual dose titration of ketamine for management of neuropathic pain can prevent psychotomimetic effects in patients with advanced cancer.

Beneficial effects of adding ketamine to intravenous patient-controlled analgesia with fentanyl after the Nuss procedure in pediatric patients

PURPOSE

The aim of this prospective, double-blind, randomized study was to investigate the analgesic effects of low-dose ketamine on intravenous patient-controlled analgesia (IV-PCA) with fentanyl for pain control in pediatric patients following the Nuss procedure for pectus excavatum.

MATERIALS AND METHODS

Sixty pediatric patients undergoing the Nuss procedure were randomly assigned to receive fentanyl (Group F, n=30) or fentanyl plus ketamine (Group FK, n=30). Ten minutes before the end of surgery, following the loading dose of each solution, 0.5 μg/kg/hr of fentanyl or 0.5 μg/kg/hr of fentanyl plus 0.15 mg/kg/hr of ketamine was infused via an IV-PCA pump (basal rate, 1 mL/hr; bolus, 0.5 mL; lock out interval, 30 min). Fentanyl consumption, pain score, ketorolac use, nausea/vomiting, ondansetron use, pruritus, respiratory depression, hallucination, dreaming, and parent satisfaction with pain control were measured throughout the 48 hours following surgery.

RESULTS

The pain scores, ketorolac use, and fentanyl consumption of Group FK were significantly lower than in Group F (p<0.05). The incidence of nausea/vomiting and ondansetron use in Group FK was significantly lower than in Group F (p<0.05). There were no reports of respiratory depression, hallucination or dreaming. Parent satisfaction with pain control was similar between the two groups.

CONCLUSION

We concluded that low-dose ketamine added to IV-PCA with fentanyl after the Nuss procedure in pediatric patients can reduce pain scores, consumption of fentanyl, and incidence of nausea/vomiting without increasing side effects.

Morphine and ketamine is superior to morphine alone for out-of-hospital trauma analgesia: a randomized controlled trial

STUDY OBJECTIVE

We assess the efficacy of intravenous ketamine compared with intravenous morphine in reducing pain in adults with significant out-of-hospital traumatic pain.

METHODS

This study was an out-of-hospital, prospective, randomized, controlled, open-label study. Patients with trauma and a verbal pain score of greater than 5 after 5 mg intravenous morphine were eligible for enrollment. Patients allocated to the ketamine group received a bolus of 10 or 20 mg, followed by 10 mg every 3 minutes thereafter. Patients allocated to the morphine alone group received 5 mg intravenously every 5 minutes until pain free. Pain scores were measured at baseline and at hospital arrival.

RESULTS

A total of 135 patients were enrolled between December 2007 and July 2010. There were no differences between the groups at baseline. After the initial 5-mg dose of intravenous morphine, patients allocated to ketamine received a mean of 40.6 mg (SD 25 mg) of ketamine. Patients allocated to morphine alone received a mean of 14.4 mg (SD 9.4 mg) of morphine. The mean pain score change was -5.6 (95% confidence interval [CI] -6.2 to -5.0) in the ketamine group compared with -3.2 (95% CI -3.7 to -2.7) in the morphine group. The difference in mean pain score change was -2.4 (95% CI -3.2 to -1.6) points. The intravenous morphine group had 9 of 65 (14%; 95% CI 6% to 25%) adverse effects reported (most commonly nausea [6/65; 9%]) compared with 27 of 70 (39%; 95% CI 27% to 51%) in the ketamine group (most commonly disorientation [8/70; 11%]).

CONCLUSION

Intravenous morphine plus ketamine for out-of-hospital adult trauma patients provides analgesia superior to that of intravenous morphine alone but was associated with an increase in the rate of minor adverse effects.

Does adding ketamine to morphine patient-controlled analgesia safely improve post-thoracotomy pain?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was 'is the addition of ketamine to morphine patient-controlled analgesia (PCA) following thoracic surgery superior to morphine alone'. Altogether 201 papers were found using the reported search, of which nine represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. This consisted of one systematic review of PCA morphine with ketamine (PCA-MK) trials, one meta-analysis of PCA-MK trials, four randomized controlled trials of PCA-MK, one meta-analysis of trials using a variety of peri-operative ketamine regimes and two cohort studies of PCA-MK. Main outcomes measured included pain score rated on visual analogue scale, morphine consumption and incidence of psychotomimetic side effects/hallucination. Two papers reported the measurements of respiratory function. This evidence shows that adding ketamine to morphine PCA is safe, with a reported incidence of hallucination requiring intervention of 2.9%, and a meta-analysis finding an incidence of all central nervous system side effects of 18% compared with 15% with morphine alone, P = 0.31, RR 1.27 with 95% CI (0.8-2.01). All randomized controlled trials of its use following thoracic surgery found no hallucination or psychological side effect. All five studies in thoracic surgery (n = 243) found reduced morphine requirements with PCA-MK. Pain scores were significantly lower in PCA-MK patients in thoracic surgery papers, with one paper additionally reporting increased patient satisfaction. However, no significant improvement was found in a meta-analysis of five papers studying PCA-MK in a variety of surgical settings. Both papers reporting respiratory outcomes found improved oxygen saturations and PaCO(2) levels in PCA-MK patients following thoracic surgery. We conclude that adding low-dose ketamine to morphine PCA is safe and post-thoracotomy may provide better pain control than PCA with morphine alone (PCA-MO), with reduced morphine consumption and possible improvement in respiratory function. These studies thus support the routine use of PCA-MK instead of PCA-MO to improve post-thoracotomy pain control.