Impact of Low-Dose Ketamine on the Usage of Continuous Opioid Infusion for the Treatment of Pain in Adult Mechanically Ventilated Patients in Surgical Intensive Care Units

Experiential Learning with Ketamine: A Mixed-Methods Exploratory Study on Prescription and Perception

Background

Incorporating unfamiliar therapies into practice requires effective longitudinal learning and the optimal way to achieve this is debated. Though not a novel therapy, ketamine in critical care has a paucity of data and variable acceptance, with limited research describing intensivist perceptions and utilization. The Coronavirus-19 pandemic presented a particular crisis where providers rapidly adapted analgosedation strategies to achieve prolonged, deep sedation due to a surge of severe acute respiratory distress syndrome (ARDS).

Question

How does clinical experience with ketamine impact the perception and attitude of clinicians toward this therapy?

Methods

We conducted a mixed-methods study using quantitative ketamine prescription data and qualitative focus group data. We analyzed prescription patterns of ketamine in a tertiary academic ICU during two different time points: pre-COVID-19 (March 1-June 30, 2019) and during the COVID-19 surge (March 1-June 30, 2020). Two focus groups (FG) of critical care attendings were held, and data were analyzed using the Framework Method for content analysis.

Results

Four-hundred forty-six medical ICU patients were mechanically ventilated (195 pre-COVID-19 and 251 during COVID-19). The COVID-19 population was more likely to receive ketamine (81[32.3%] vs 4 [2.1%], p < 0.001). Thirteen respondents participated across two FG sessions (Pre-COVID = 8, Post-COVID=5). The most prevalent attitude among our respondents was discomfort, with three key themes identified as follows: 1) lack of evidence regarding ketamine, 2) lack of personal experience, and 3) desire for more education and protocols.

Conclusion

Despite a substantial increase in ketamine prescription during COVID-19, intensivists continued to feel discomfort with utilization. Factors contributing to this discomfort include a lack of evidence, a lack of experience, and a desire for more education and protocols. Increase in experience with ketamine alone was not sufficient to minimize provider discomfort. These findings should inform future curricula and call for process improvement to optimize continuing education.

Continuous Infusion of Ketamine in Mechanically Ventilated Patients with SARS-CoV-2

Background

Widespread drug shortages led to higher utilization of ketamine in our intensive care unit, especially among patients with SARS-CoV-2.

Objectives

To evaluate the impact of continuous infusion of ketamine on vasopressor requirements in patients with SARS-CoV-2.

Method

This was a single-center, retrospective, cohort study comparing mechanically ventilated (MV), adult patients with SARS-CoV-2 receiving either propofol or ketamine for at least 72 hours.

Results

84 patients (mean age of 61-year-old, 68% male) were analyzed. 31 patients received ketamine, and 53 patients received propofol. Mean vasopressor doses were not significantly different between ketamine and propofol groups at prespecified timepoints. However, mean arterial pressures (MAP) were higher in the ketamine group at 24 h, 48 h, and 96 h postsedative initiation. The median opioid infusion requirements were 3 vs. 12.5 mg/hr (p < 0.0001) for ketamine and propofol groups, respectively. Comparing to propofol, C-reactive protein (CRP) values were significantly lower in the ketamine group at 24 h (7.53 vs. 15.9 mg/dL, p=0.03), 48 h (5.23 vs. 14.1 mg/dL, p=0.0083), and 72 h (6.4 vs. 12.1 mg/dL, p=0.0085).

Conclusion

In patients with SARS-CoV-2 on MV, there was no difference in the vasopressor requirement in patients receiving ketamine compared to propofol. Nevertheless, the use of ketamine was associated with higher MAP, reductions in CRP in select timepoints, and overall lower opioid requirements.

Ketamine for Primary Analgosedation in Critically Ill Surgery and Trauma Patients Requiring Mechanical Ventilation

OBJECTIVES

Evaluate effectiveness and safety outcomes associated with the use of ketamine for primary analgosedation in the surgical/trauma ICU setting.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center in Minnesota.

PATIENTS

Patients admitted to the surgical ICU between 2015 and 2019 requiring mechanical ventilation and meeting one of three definitions for ketamine primary analgosedation were included: 1) no concomitant opioid infusion, 2) ketamine monotherapy for greater than or equal to 6 hours with subsequent opioid infusion, or 3) ketamine initiated concomitantly or within 4 hours of opioid and total opioid duration less than 4 hours.

INTERVENTIONS

None.

MEASUREMENTS

Use of ketamine, analgesics, and sedatives were evaluated. Pain, sedation, and delirium assessments immediately before and during ketamine infusion were collected and compared with reported goals. Concomitant analgesics, sedatives, and psychotropics were recorded. Reported failures due to ineffectiveness and toxicity were collected.

MAIN RESULTS

Of 164 included patients, 88% never received a concomitant opioid infusion (primary analgosedation definition 1), 12% met alternative criteria for primary analgosedation (definitions 2 and 3). A majority, 68%, were surgical admissions and mean Acute Physiology and Chronic Health Evaluation III score was 90 (± 30). Median mechanical ventilation duration was 2.5 days (1.1-4.5) and ICU length of stay of 4.9 days (3-8). The median ketamine infusion dose and duration were 0.18 mg/kg/hr (0.1-0.3) and 30 hours (15.1-51.8). Concomitant infusions of propofol and dexmedetomidine were administered in 49% and 29% of patients, respectively. During ketamine infusion, the median percent of total pain scores at goal was 62% (33-96%), while 64% (37-91%) of Richmond Agitation Sedation Scale scores were at goal, and 47% of patients were Confusion Assessment Method-ICU positive during the ketamine infusion. Hallucinations were documented in 14% of patients and ketamine failure occurred in 11% of patients.

CONCLUSIONS

Ketamine may be an effective primary analgosedation option in intubated surgical ICU patients, but prospective randomized studies are needed to evaluate this strategy.

The impact of ketamine on outcomes in critically ill patients: a systematic review with meta-analysis and trial sequential analysis of randomized controlled trials

BACKGROUND

This meta-analysis aims to evaluate the effects of ketamine in critically ill intensive care unit (ICU) patients.

METHODS

We searched for randomized controlled trials (RCTs) in PubMed, Scopus, and the Cochrane Library; the search was performed initially in January but was repeated in December of 2023. We focused on ICU patients of any age. We included studies that compared ketamine with other traditional agents used in the ICU. We synthesized evidence using RevMan v5.4 and presented the results as forest plots. We also used trial sequential analysis (TSA) software v. 0.9.5.10 Beta and presented results as TSA plots. For synthesizing results, we used a random-effects model and reported differences in outcomes of two groups in terms of mean difference (MD), standardized MD, and risk ratio with 95% confidence interval. We assessed the risk of bias using the Cochrane RoB tool for RCTs. Our outcomes were mortality, pain, opioid and midazolam requirements, delirium rates, and ICU length of stay.

RESULTS

Twelve RCTs involving 805 ICU patients (ketamine group, n=398; control group, n=407) were included in the meta-analysis. The ketamine group was not superior to the control group in terms of mortality (in five studies with 318 patients), pain (two studies with 129 patients), mean and cumulative opioid consumption (six studies with 494 patients), midazolam consumption (six studies with 304 patients), and ICU length of stay (three studies with 270 patients). However, the model favored the ketamine group over the control group in delirium rate (four studies with 358 patients). This result is significant in terms of conventional boundaries (alpha=5%) but is not robust in sequential analysis. The applicability of the findings is limited by the small number of patients pooled for each outcome.

CONCLUSIONS

Our meta-analysis did not demonstrate differences between ketamine and control groups regarding any outcome except delirium rate, where the model favored the ketamine group over the control group. However, this result is not robust as sensitivity analysis and trial sequential analysis suggest that more RCTs should be conducted in the future.

Prevalence of Delirium After Abdominal Surgery and Association With Ketamine: A Retrospective, Propensity-Matched Cohort Study

IMPORTANCE

Delirium is a common postoperative complication for older patients in the ICU. Ketamine, used primarily as an analgesic, has been thought to prevent delirium.

OBJECTIVE

Determine the prevalence and association of delirium with low-dose ketamine use in ICU patients after abdominal surgery.

DESIGN

Single-center, retrospective, propensity-matched cohort study.

SETTING

Eight hospital academic medical center.

PATIENTS

Cohort comprising 1836 patients admitted to the ICU after abdominal surgery between June 23, 2018 and September 1, 2022.

MAIN OUTCOMES AND MEASURES

Propensity score matching (PSM) with a 3:1 ratio between no-ketamine use and ketamine use was performed through a greedy algorithm (caliper of 0.005). Outcomes of interest included: delirium (assessed by Confusion Assessment Method-ICU), mean pain score (Numeric Pain Scale or Critical Care Pain Observation Tool score as available), mean opioid consumption (morphine milligram equivalents), length of stay (d), and mortality.

RESULTS

Prevalence of delirium was 47.71% (95% CI, 45.41-50.03%) in the cohort. Of 1836 patients, 120 (6.54%) used low-dose ketamine infusion. After PSM, the prevalence of delirium was 56.02% (95% CI, 51.05-60.91%) in all abdominal surgery patients. The ketamine group had 41% less odds of delirium (odds ratio [OR] = 0.59; 95% CI, 0.37-0.94; p = 0.026) than patients with no-ketamine use. Patients with ketamine use had higher mean pain scores (3.57 ± 2.86 vs. 2.21 ± 2.09, p < 0.001). In the subgroup analysis, patients in the ketamine-use group 60 years old or younger had 64% less odds of delirium (OR = 0.36; 95% CI, 0.13-0.95; p = 0.039). The mean pain scores were higher in the ketamine group for patients 60 years old or older. There was no significant difference in mortality and opioid consumption.

CONCLUSIONS AND RELEVANCE

Low-dose ketamine infusion was associated with lower prevalence of delirium in ICU patients following abdominal surgery. Prospective studies should further evaluate ketamine use and delirium.

Application of Ketamine in Pain Management and the Underlying Mechanism

Since ketamine was approved by the FDA as an intravenous anesthetic, it has been in clinical use for more than 50 years. Apart from its anesthetic effects, ketamine is one of the few intravenous anesthetics with potent analgesic properties. As part of the effort to develop pain management, renewed interest has focused on the use of ketamine for the treatment of acute and chronic pain. Ketamine is commonly used to treat various kinds of chronic pain syndromes and is also applied to control perioperative pain and reduce the consumption of postoperative analgesics. However, its precise mechanisms of action remain mysterious for a large part. Despite extensive research in the field, the mechanism of ketamine is still unclear. Its analgesic effect appears to be largely mediated by blockade of NMDARs, but opioid, GABA, and monoaminergic system seem to partly participate in the pain transmission procedure. Its metabolites also have an analgesic effect, which may prolong pain relief. More recently, the antidepressant effect of ketamine has been considered to reduce pain-related aversion to relieve chronic pain. Overall, the analgesic mechanism of ketamine seems to be a complex combination of multiple factors. Due to its potent analgesic properties, ketamine is an analgesic with great clinical application prospects. Exploring the precise mechanism of action of ketamine will help guide clinical medication and confirm indications for ketamine analgesia. This review aims to list the application of ketamine in pain management and discuss its analgesic mechanism.

Prospective observational study on the use of continuous intravenous ketamine and propofol infusion for prolonged sedation in critical care

INTRODUCTION

Analgesia and sedation are a priority in paediatric intensive care. The combination of ketamine and propofol is a possible option in patients requiring prolonged or difficult sedation and to reduce the use of benzodiazepines and opiates. The aim of this study was to assess the efficacy and safety of combination ketamine and propofol in continuous infusion for prolonged analgesia/sedation in the paediatric intensive care setting.

PATIENTS AND METHODS

Prospective, observational single-group cohort study in patients aged 1 month to 16 years admitted to the paediatric intensive care unit in 2016-2018 that received ketamine and propofol in continuous infusion for analgesia and sedation. We collected data on demographic and clinical characteristics, analgesia and sedation scores (MAPS, COMFORT-B and SOPHIA), haemodynamic parameters and adverse events.

RESULTS

The study included 32 patients. The maximum dose of ketamine was 1.5 mg/kg/h (interquartile range [IQR], 1-2 mg/kg/h) and the infusion duration was 5 days (IQR, 3-5 days). The maximum dose of propofol was 3.2 mg/kg/h (IQR, 2.5-3.6 mg/kg/h) and the infusion duration, 5 days (IQR, 3-5 days). Thirty (93.7%) patients had previously received midazolam and 29 (90.6%) fentanyl. Analgesia scores did not change after initiation of the ketamine and propofol infusion. There was a statistically significant increase in the COMFORT-B score, but the score remained in the adequate sedation range (12-17). There were small but statistically significant decreases in the mean arterial pressure (from 64 mmHg to 60 mmHg; P = .006) and the diastolic blood pressure (from 50.5 to 48 mmHg; P = .023) 1 h after the initiation of the ketamine and propofol infusion, but this difference was not observed 12 h later and did not require administration of vasoactive drugs. No other major adverse events were detected during the infusion.

CONCLUSIONS

The combination of ketamine and propofol in continuous infusion is a safe treatment in critically ill children that makes it possible to achieve an appropriate level of analgesia and sedation without relevant haemodynamic repercussions.

Safety and feasibility of continuous ketamine infusion for analgosedation in medical and cardiac ICU patients who received mechanical ventilation support: A retrospective cohort study

Purpose

To assess the effect of continuous ketamine administration in patients admitted to medical and cardiac intensive care units (ICUs) and received mechanical ventilation support.

Methods

We conducted a retrospective cohort study between March 2012 and June 2020 at an academy-affiliated tertiary hospital. Adult patients who received mechanical ventilation support for over 24 h and continuous ketamine infusion for at least 8 h were included. The primary outcome was immediate hemodynamic safety after continuous ketamine infusion. The secondary outcomes included immediate delirium, pain, and use of sedation.

Results

Of all 12,534 medical and cardiac ICU patients, 564 were eligible for the analysis. Ketamine was used for 33.3 (19.0–67.5) h and the median continuous infusion dose was 0.11 (0.06–0.23) mcg/kg/h. Of all patients, 469 (83.2%) received continuous ketamine infusion concomitant with analgosedation. Blood pressure and vasopressor inotropic scores did not change after continuous ketamine infusion. Heart rate decreased significantly from 106.9 (91.4–120.9) at 8 h before ketamine initiation to 99.8% (83.9–114.4) at 24 h after ketamine initiation. In addition, the respiratory rate decreased from 21.7 (18.6–25.4) at 8 h before ketamine initiation to 20.1 (17.0–23.0) at 24 h after ketamine initiation. Overall opioid usage was significantly reduced: 3.0 (0.0–6.0) mcg/kg/h as fentanyl equivalent dose at 8 h before ketamine initiation to 1.0 (0.0–4.1) mcg/kg/h as fentanyl equivalent dose at 24 h post-ketamine initiation. However, the use of sedatives and antipsychotic medications did not decrease. In addition, ketamine did not increase the incidence of delirium within 24 h after ketamine infusion.

Conclusion

Ketamine may be a safe and feasible analgesic for medical and cardiac ICU patients who received mechanical ventilation support as an opioid-sparing agent without adverse hemodynamic effects.

Pain assessment and analgesic management in patients admitted to intensive care: an Australian and New Zealand point prevalence study

Objective: To describe pain assessment and analgesic management practices in patients in intensive care units (ICUs) in Australia and New Zealand. Design, setting and participants: Prospective, observational, multicentre, single-day point prevalence study conducted in Australian and New Zealand ICUs. Observational data were recorded for all adult patients admitted to an ICU without a neurological, neurosurgical or postoperative cardiac diagnosis. Demographic characteristics and data on pain assessment and analgesic management for a 24-hour period were collected. Main outcome measures: Types of pain assessment tools used and frequency of their use, use of opioid analgesia, use of adjuvant analgesia, and differences in pain assessment and analgesic management between postoperative and non-operative patients. Results: From the 499 patients enrolled from 45 ICUs, pain assessment was performed at least every 4 hours in 56% of patients (277/499), most commonly with a numerical rating scale. Overall, 286 patients (57%) received an opioid on the study day. Of the 181 mechanically ventilated patients, 135 (75%) received an intravenous opioid, with the predominant opioid infusion being fentanyl. The median dose of opioid infusion for ventilated patients was 140 mg oral morphine equivalents. Of the 318 non-ventilated patients, 41 (13%) received patient-controlled analgesia and 76 (24%) received an oral opioid, with the predominant opioid being oxycodone. Paracetamol was administered to 63 ventilated patients (35%) and 164 non-ventilated patients (52%), while 2% of all patients (11/499) received a non-steroidal anti-inflammatory drug. Ketamine infusion and regional analgesia were used in 15 patients (3%) and 17 patients (3%), respectively. Antineuropathic agents (predominantly gabapentinoids) were used in 53 patients (11%). Conclusions: Although a majority of ICU patients were frequently assessed for pain with a validated pain assessment tool, cumulative daily doses of opioids were high, and the use of multimodal adjuvant analgesia was low. Our data on current pain assessment and analgesic management practices may inform further research in this area.

Incidence of Dissociation With Low-Dose Pre-hospital Ketamine in Geriatric Patients With Trauma-Related Pain

Introduction

Sub-dissociative ketamine has been used increasingly for the treatment of acute pain in a wide variety of settings. While there are studies evaluating its use in the geriatric population, no studies have described its safety in the pre-hospital geriatric trauma patient. The objective of this study was to define the incidence of dissociation with low-dose pre-hospital ketamine in geriatric trauma patients.

Methods

Using our county emergency medical services database, we identified all trauma patients greater or equal to 65 years of age who received pre-hospital ketamine for pain after the implementation of a low-dose ketamine protocol. We retrospectively reviewed pre-hospital and emergency department records for demographics, traumatic injuries, Glasgow Coma Score, emergency department length of stay and disposition, and hospital length of stay. This group was compared to a similar population of trauma patients, transported prior to the ketamine protocol. The comparison group was chosen by matching the ketamine group to more than double the number of non-ketamine patients. Records were obtained from two separate trauma centers. Our primary outcome was documentation of “ketamine-related dissociation” by either the pre-hospital, emergency department or trauma provider. Secondary outcomes included emergency department length of stay and intensive care unit admission.

Results

Seventy-nine patients received ketamine with records available for analysis. One hundred ninety-three non-ketamine patients were compared to this group. There were nosignificant differences between the two groups in regards to age, weight, gender, or mechanism of injury. The injury severity score was higher in the ketamine group. Nine patients (11%) had documented dissociation after ketamine, with six of these patients back to baseline mentation by arrival to the emergency department. The emergency department length of stay was shorter in the ketamine group. The rate of intensive care unit admission was the same between both groups.

Conclusions

Pre-hospital sub-dissociative ketamine in geriatric trauma patients is associated with brief episodes of dissociation in a small minority of patients.

Efficacy and safety of ketamine in mechanically ventilated intensive care unit patients: a scoping review

Objectives: Mechanically ventilated patients account for about one-third of all admissions to the intensive care unit (ICU). Ketamine has been conditionally recommended to aid with analgesia in such patients, with low quality of evidence available to support this recommendation. We aimed to perform a narrative scoping review of the current knowledge of the use of ketamine, with a specific focus on mechanically ventilated ICU patients. Methods: We searched MEDLINE and EMBASE for relevant articles. Bibliographies of retrieved articles were examined for references of potential relevance. We included studies that described the use of ketamine for postoperative and emergency department management of pain and in the critically unwell, mechanically ventilated population. Results: There are few randomised controlled trials evaluating ketamine's utility in the ICU. The evidence is predominantly retrospective and observational in nature and the results are heterogeneous. Available evidence is summarised in a descriptive manner, with a division made between high dose and low dose ketamine. Ketamine's pharmacology and use as an analgesic agent outside of the ICU is briefly discussed, followed by evidence for use in the ICU setting, with particular emphasis on analgesia, sedation and intubation. Finally, data on adverse effects including delirium, coma, haemodynamic adverse effects, raised intracranial pressure, hypersalivation and laryngospasm are presented. Conclusions: Ketamine is used in mechanically ventilated ICU patients with several potentially positive clinical effects. However, it has a significant side effect profile, which may limit its use in these patients. The role of low dose ketamine infusion in mechanically ventilated ICU patients is not well studied and requires investigation in high quality, prospective randomised trials.

Multicenter Retrospective Review of Ketamine Use in the ICU

IMPORTANCE:

The response of ICU patients to continuously infused ketamine when it is used for analgesia and/or sedation remains poorly established.

OBJECTIVES:

To describe continuous infusion (CI) ketamine use in critically ill patients, including indications, dose and duration, adverse effects, patient outcomes, time in goal pain/sedation score range, exposure to analgesics/sedatives, and delirium.

DESIGN, SETTING, AND PARTICIPANTS:

Multicenter, retrospective, observational study from twenty-five diverse institutions in the United States. Patients receiving CI ketamine between January 2014 and December 2017.

MAIN OUTCOMES AND MEASURES:

Chart review evaluating institutional and patient demographics, ketamine indication, dose, administration, and adverse effects. Pain/sedation scores, cumulative doses of sedatives and analgesics, and delirium screenings in the 24 hours prior to ketamine were compared with those at 0–24 hours and 25–48 hours after.

RESULTS:

A total of 390 patients were included (median age, 54.5 yr; interquartile range, 39–65 yr; 61% males). Primary ICU types were medical (35.3%), surgical (23.3%), and trauma (17.7%). Most common indications were analgesia/sedation (n = 357, 91.5%). Starting doses were 0.2 mg/kg/hr (0.1–0.5 mg/kg/hr) and continued for 1.6 days (0.6–2.9 d). Hemodynamics in the first 4 hours after ketamine were variable (hypertension 24.0%, hypotension 23.5%, tachycardia 19.5%, bradycardia 2.3%); other adverse effects were minimal. Compared with 24 hours prior, there was a significant increase in proportion of time spent within goal pain score after ketamine initiation (24 hr prior: 68.9% [66.7–72.6%], 0–24 hr: 78.6% [74.3–82.5%], 25–48 hr: 80.3% [74.6–84.3%]; p < 0.001) and time spent within goal sedation score (24 hr prior: 57.1% [52.5–60.0%], 0–24 hr: 64.1% [60.7–67.2%], 25–48 hr: 68.9% [65.5–79.5%]; p < 0.001). There was also a significant reduction in IV morphine (mg) equivalents (24 hr prior: 120 [25–400], 0–24 hr: 118 [10–363], 25–48 hr: 80 [5–328]; p < 0.005), midazolam (mg) equivalents (24 hr prior: 11 [4–67], 0–24 hr: 6 [0–68], 25–48 hr: 3 [0–57]; p < 0.001), propofol (mg) (24 hr prior: 942 [223–4,018], 0–24 hr: 160 [0–2,776], 25–48 hr: 0 [0–1,859]; p < 0.001), and dexmedetomidine (µg) (24 hr prior: 1,025 [276–1,925], 0–24 hr: 285 [0–1,283], 25–48 hr: 0 [0–826]; p < 0.001). There was no difference in proportion of time spent positive for delirium (24 hr prior: 43.0% [17.0–47.0%], 0–24 hr: 39.5% [27.0–43.8%], 25–48 hr: 0% [0–43.7%]; p = 0.233). Limitations to these data include lack of a comparator group, potential for confounders and selection bias, and varying pain and sedation practices that may have changed since completion of the study.

CONCLUSIONS AND RELEVANCE:

There is variability in the use of CI ketamine. Hemodynamic instability was the most common adverse effect. In the 48 hours after ketamine initiation compared with the 24 hours prior, proportion of time spent in goal pain/sedation score range increased and exposure to other analgesics/sedatives decreased.

Prevention of Acute Postoperative Pain in Breast Cancer: A Comparison between Opioids versus Ketamine in the Intraoperatory Analgesia

Background

Acute postoperative pain (APP) has a high incidence in breast surgery, and opioids are the most commonly used drugs for its management; however, they are not free from systemic side effects, which may increase comorbidity. In the past few years, opioid-free anaesthesia has been favoured with promising results.

Methods

We conducted a descriptive study including 71 patients who underwent breast cancer surgery. The opioid group (n = 41) received fentanyl for induction, remifentanil for maintenance, and rescue morphine before waking up, whereas the ketamine group (n = 30) received a ketamine bolus for induction followed by continuous ketamine infusion during surgery. Later, the presence and intensity of pain were registered, using the Numeric Rating Scale (NRS 1-10) for pain, at different times in the recovery room, at 24 hours and at 3 months.

Results

Administration of ketamine is more effective than opioid use for APP prevention in breast cancer surgery because the ketamine group presented with less pain than the opioid group (p < 0.05) at all measured times. When there was pain, patients in the ketamine group gave a lower score to its intensity (p < 0.05).

Conclusions

Ketamine could reduce the incidence of APP in breast cancer surgery, compared to opioids.

Pain Management Considerations in Patients with Opioid Use Disorder Requiring Critical Care

The opioid epidemic has resulted in increased opioid-related critical care admissions, presenting challenges in acute pain management. Limited guidance exists in the management of critically ill patients with opioid use disorder (OUD). This narrative review provides the intensive care unit (ICU) clinician with guidance and treatment options, including non-opioid analgesia, for patients receiving medications for opioid use disorder (MOUD) and for patients actively misusing opioids. Verification and continuation of the patient's outpatient MOUD regimen, specifically buprenorphine and methadone formulations, assessment of pain and opioid withdrawal, and treatment of acute pain with non-opioid analgesia, nonpharmacologic strategies, and short-acting opioids as needed, are all essential to adequate management of acute pain in patients with OUD. A multidisciplinary approach to treatment and discharge planning in patients with OUD may be beneficial to engage patients with OUD early in their hospital stay to prevent withdrawal, stabilize their OUD, and to reduce the risk of unplanned discharge and other associated morbidity. This article is protected by copyright. All rights reserved.

Impact of ketamine as an adjunct sedative in acute respiratory distress syndrome due to COVID-19 Pneumonia

Purpose

Deep sedation is sometimes needed in acute respiratory distress syndrome. Ketamine is a sedative that has been shown to have analgesic and sedating properties without having a detrimental impact on hemodynamics. This pharmacological profile makes ketamine an attractive sedative, potentially reducing the necessity for other sedatives and vasopressors, but there are no studies evaluating its effect on these medications in patients requiring deep sedation for acute respiratory distress syndrome.

Materials and methods

This is a retrospective, observational study in a single center, quaternary care hospital in southeast Texas. We looked at adults with COVID-19 requiring mechanical ventilation from March 2020 to September 2020.

Results

We found that patients had less propofol requirements at 72 h after ketamine initiation when compared to 24 h (median 34.2 vs 54.7 mg/kg, p = 0.003). Norepinephrine equivalents were also significantly lower at 48 h than 24 h after ketamine initiation (median 38 vs 62.8 mcg/kg, p = 0.028). There was an increase in hydromorphone infusion rates at all three time points after ketamine was introduced.

Conclusions

In this cohort of patients with COVID-19 ARDS who required mechanical ventilation receiving ketamine we found propofol sparing effects and vasopressor requirements were reduced, while opioid infusions were not.

Hemodynamic Effects of Ketamine Compared With Propofol or Dexmedetomidine as Continuous ICU Sedation

BACKGROUND

Ketamine has seen increased use for sedation in the intensive care unit. In contrast to propofol or dexmedetomidine, ketamine may provide a positive effect on hemodynamics.

OBJECTIVE

The objective of this study was to compare the development of clinically significant hypotension or bradycardia (ie, negative hemodynamic event) between critically ill adults receiving sedation with ketamine and either propofol or dexmedetomidine.

METHODS

This was a retrospective cohort study of adults admitted to an intensive care unit at an academic medical center between January 2016 and January 2021.

RESULTS

Patients in the ketamine group (n = 78) had significantly less clinically significant hypotension or bradycardia compared with those receiving propofol or dexmedetomidine (n = 156) (34.6% vs 63.5%; P < 0.001). Patients receiving ketamine also experienced smaller degree of hypotension observed by percent decrease in mean arterial pressure (25.3% [17.4] vs 33.8% [14.5]; P < 0.001) and absolute reduction in systolic blood pressure (26.5 [23.8] vs 42.0 [37.8] mm Hg; P < 0.001) and bradycardia (15.5 [24.3] vs 32.0 [23.0] reduction in beats per minute; P < 0.001). In multivariate logistic regression modeling, receipt of propofol or dexmedetomidine was the only independent predictor of a negative hemodynamic event (odds ratio [OR]: 3.3, 95% confidence interval [CI], 1.7 to 6.1; P < 0.001).

CONCLUSION AND RELEVANCE

Ketamine was associated with less clinically relevant hypotension or bradycardia when compared with propofol or dexmedetomidine, in addition to a smaller absolute decrease in hemodynamic parameters. The clinical significance of these findings requires further investigation.

Adjunctive ketamine for sedation in critically ill mechanically ventilated patients: an active-controlled, pilot, feasibility clinical trial

OBJECTIVE

Ketamine has been shown to decrease sedative requirements in intensive care unit (ICU). Randomized trials are limited on patient-centered outcomes. We designed this pilot trial to evaluate the feasibility of a large randomized controlled trial (RCT) testing the effect of ketamine as an adjunct analgosedative compared with standard of care alone as a control group (CG) in critically ill patients with mechanical ventilation (MV). We also provided preliminary evidence on clinically relevant outcomes to plan a larger trial.

MATERIAL AND METHODS

Pilot, active-controlled, open-label RCT was conducted at medical, surgical, and transplant ICUs at a large tertiary and quaternary care medical institution (King Faisal Specialist Hospital and Research Center, Saudi Arabia). The study included adult patients who were intubated within 24 h, expected to require MV for the next calendar day, and had institutional pain and sedation protocol initiated. Patients were randomized in a 1:1 ratio to adjunct ketamine infusion 1-2 μg/kg/min for 48 h or CG alone.

RESULTS

Of 437 patients screened from September 2019 through November 2020, 83 (18.9%) patients were included (43 in CG and 40 in ketamine) and 352 (80.5%) were excluded. Average enrollment rate was 3-4 patients/month. Consent and protocol adherence rates were adequate (89.24% and 76%, respectively). Demographics were balanced between groups. Median MV duration was 7 (interquartile range [IQR] 3-9.25 days) in ketamine and 5 (IQR 2-8 days) in CG. Median VFDs was 19 (IQR 0-24.75 days) in ketamine and 19 (IQR 0-24 days) in the CG (p = 0.70). More patients attained goal Richmond Agitation-Sedation Scale at 24 and 48 h in ketamine (67.5% and 73.5%, respectively) compared with CG (52.4% and 66.7%, respectively). Sedatives and vasopressors cumulative use, and hemodynamic changes were similar. ICU length-of-stay was 12.5 (IQR 6-21.2 days) in ketamine, compared with 12 (IQR 5.5-23 days) in CG. No serious adverse events were observed in either group.

CONCLUSIONS

Ketamine as an adjunct analgosedative agent appeared to be feasible and safe with no negative impact on outcomes, including hemodynamics. This pilot RCT identified areas of improvement in study protocol before conducting a large, adequately powered, multicenter RCT which is likely justified to investigate ketamine association with patient-centered outcomes further. Trial registration ClinicalTrials.gov: NCT04075006. Registered on 30 August 2019. Current controlled trials: ISRCTN14730035. Registered on 3 February 2020.

The Reemergence of Ketamine for Treatment in Critically Ill Adults

OBJECTIVES

To assess the evidence and discuss the risks and clinical relevance of ketamine for the treatment of various disease states impacting the adult critically ill population.

DATA SOURCES

A literature review was performed using PubMed evaluating primary literature published until August 2018.

STUDY SELECTION

Case reports, observational studies (cohort, case-control), and randomized controlled trials involving patients 18 years and older in a nonperioperative setting using either IV or intramuscular ketamine were included for analysis. Uses of ketamine discussed focused on critically ill patients in the ICU and emergency department settings.

DATA EXTRACTION

Included studies were evaluated for dosing, outcomes, and adverse effects of ketamine. For each study, the design, population, intervention, investigated outcomes, and results were assessed.

DATA SYNTHESIS

The evidence was organized according to use of ketamine, which included pain, sedation, status asthmaticus, alcohol withdrawal syndrome, status epilepticus, and acute behavioral psychologic disturbances. Evaluation of the evidence was based on the included primary literature along with any related guideline recommendations.

CONCLUSIONS

Ketamine has suggested potential benefit in several disease states impacting critically ill patients including pain, alcohol withdrawal syndrome, status epilepticus, and acute agitation. Further supporting evidence is needed to validate its use in the setting of critical illness.

Ketamine for Pain Management: A Review of Literature and Clinical Application

Ketamine is a dissociative anesthetic used increasingly as analgesia for different manifestations of pain, including acute, chronic, cancer and perioperative pain as well as pain in the critically ill patient population. Its distinctive pharmacologic properties may provide benefits to individuals suffering from pain, including increased pain control and reduction in opioid consumption and tolerance. Despite wide variability in proposed dosing and method of administration when used for analgesia, it is important all clinicians be familiar with the pharmacodynamics of ketamine in order to appropriately anticipate its therapeutic and adverse effects.

An Analysis of Prolonged, Continuous Ketamine Infusions

INTRODUCTION

Opioids carry high risk of dependence, and patients can rapidly build tolerance after repetitive dosing. Low-dose ketamine is an analgesic agent alternative that provides more hemodynamic stability. We sought to describe the effects of prolonged ketamine use in non-burn patients.

MATERIALS AND METHODS

We queried the electronic health system at the Brooke Army Medical Center for patient encounters with ketamine infusions lasting >72 hours. We abstracted data describing demographics, vital signs, ketamine infusion dose and duration, and discharge diagnoses potentially relevant to ketamine side effects.

RESULTS

We identified 194 subjects who met the study inclusion criteria. The median age was 39 years, most were male (67.0%), and most were primarily admitted for a non-trauma reason (59.2%). The mean ketamine drip strength was 43.9 mg/h (95% CI, 36.7-51.1; range 0.1-341.6) and the mean drip length was 130.8 hours (95% CI, 120.3-141.2; range 71-493). Most subjects underwent mechanical ventilation (56.1%) at some point during the infusion and most survived to hospital discharge (83.5%). On a per-day basis, the average heart rate was 93 beats per minute, systolic blood pressure was 128 mmHg, diastolic blood pressure was 71 mmHg, oxygen saturation was 96%, and respiratory rate was 22 respirations per minute.

CONCLUSIONS

We demonstrate that continuous ketamine infusions provide a useful adjunct for analgesia and/or sedation. Further development of this adjunct modality may serve as an alternative agent to opioids.

Reducing Opioid Use in Patients Undergoing Cardiac Surgery - Preoperative, Intraoperative, and Critical Care Strategies

Patients undergoing cardiothoracic surgery are exposed to opioids in the operating room and intensive care unit and after hospital discharge. Opportunities exist to reduce perioperative opioid use at all stages of care and include alternative oral and intravenous medications, novel intraoperative regional anesthetic techniques, and postoperative opioid-sparing sedative and analgesic strategies. In this review, currently used and investigational strategies to reduce the opioid burden for cardiothoracic surgical patients are explored.

Adjunct low-dose ketamine infusion vs standard of care in mechanically ventilated critically ill patients at a Tertiary Saudi Hospital (ATTAINMENT Trial): study protocol for a randomized, prospective, pilot, feasibility trial

Background

A noticeable interest in ketamine infusion for sedation management has developed among critical care physicians for critically ill patients. The 2018 Pain, Agitation/sedation, Delirium, Immobility, and Sleep disruption guideline suggested low-dose ketamine infusion as an adjunct to opioid therapy to reduce opioid requirements in post-surgical patients in the intensive care unit (ICU). This was, however, rated as conditional due to the very low quality of evidence. Ketamine has favorable characteristics, making it an especially viable alternative for patients with respiratory and hemodynamic instability. The Analgo-sedative adjuncT keTAmine Infusion iN Mechanically vENTilated ICU patients (ATTAINMENT) trial aims to assess the effect and safety of adjunct low-dose continuous infusion of ketamine as an analgo-sedative compared to standard of care in critically ill patients on mechanical ventilation (MV) for ≥ 24 h.

Methods/design

This trial is a prospective, randomized, active controlled, open-label, pilot, feasibility study of adult ICU patients (> 14 years old) on MV. The study will take place in the adult ICUs in the King Faisal Specialist Hospital and Research Center (KFSH&RC), Riyadh, Saudi Arabia, and will enroll 80 patients. Patients will be randomized post-intubation into two groups: the intervention group will receive an adjunct low-dose continuous infusion of ketamine plus standard of care. Ketamine will be administered over a period of 48 h at a fixed infusion rate of 2 μg/kg/min (0.12 mg/kg/h) in the first 24 h followed by 1 μg/kg/min (0.06 mg/kg/h) in the second 24 h. The control group will receive standard of care in the ICU (propofol and/or fentanyl and/or midazolam) according to the KFSH&RC sedation and analgesia protocol as clinically appropriate. The primary outcome is MV duration until ICU discharge, death, extubation, or 28 days post-randomization, whichever comes first.

Discussion

The first patient was enrolled on 1 September 2019. As of 10 October 2019, a total of 16 patients had been enrolled. We expect to complete the recruitment by 31 December 2020. The findings of this pilot trial will likely justify further investigation for the role of adjunct low-dose ketamine infusion as an analgo-sedative agent in a larger, multicenter, randomized controlled trial.

Trial registration

ClinicalTrials.gov: NCT04075006. Registered on 30 August 2019. Current controlled trials: ISRCTN14730035. Registered on 3 February 2020.

Opioid and Benzodiazepine Iatrogenic Withdrawal Syndrome in Patients in the Intensive Care Unit

Iatrogenic withdrawal syndrome is an increasingly recognized issue among adult patients in the intensive care unit. The prolonged use of opioids and benzodiazepines during the intensive care unit stay and preexisting disorders associated with their use put patients at risk of developing iatrogenic withdrawal syndrome. Although research to date is scant regarding iatrogenic withdrawal syndrome in adult patients in the intensive care unit, it is important to recognize and adequately manage iatrogenic withdrawal syndrome in order to prevent possible negative outcomes during and after a patient's intensive care unit stay. This article discusses in depth 8 studies of iatrogenic withdrawal syndrome among adult patients in the intensive care unit. It also addresses important aspects of opioid and benzodiazepine iatrogenic withdrawal syndrome, including prevalence, risk factors, and assessment and considers its prevention and management.

Attempts to Limit Opioid Prescribing in Critically Ill Patients: Not So Easy, Not So Fast

OBJECTIVE

To discuss why opioids have been considered the long-standing first-line therapy for treating acute, severe nociceptive pain in critically ill patients and discuss considerations for limiting opioid overuse in the intensive care unit setting.

DATA SOURCES

Articles were identified through searches of PubMed and EMBASE from database inception until December 2018. Additional references were located through a review of the bibliographies of articles and clinical practice guidelines.

STUDY SELECTION AND DATA EXTRACTION

Original research articles excluding case reports were included if they concerned nonopioid agents for pain management in critically ill patients. The focus was on studies not included in the most recent pain management guidelines.

DATA SYNTHESIS

Ten studies were retrieved. Nonopioid therapies or opioid-sparing therapies have been touted as possible alternatives for critically ill patients, but they have particular adverse effects concerns in critically ill patients, often lack parenteral dosage forms, and frequently require dose adjustment or avoidance in patients with renal or hepatic dysfunction. Relevance to Patient Care and Clinical Practice: There is a well-recognized opioid epidemic that has been the subject of much discussion. Attempts to control the epidemic have focused on limiting opioid prescribing and using nonopioid alternatives, but there are special considerations when treating severe pain in critically ill patients that often preclude nonopioid analgesics.

CONCLUSIONS

There continues to be an unmet need for medications that are as effective as opioids for severe nociceptive pain in critically ill patients but without the adverse effect and abuse concerns. Until such medications are available, clinicians need to optimize prescribing of opioid and nonopioid analgesics.

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.