Outcomes Associated with Lower Doses of Ketamine by Emergency Medical Services for Profound Agitation

Systematic review of parenteral ketamine for managing acute agitation in emergency settings

INTRODUCTION

Agitation, a significant psychiatric issue often linked to conditions like schizophrenia, bipolar disorder, and major depression, invariably pose challenges in emergency settings. Acute agitation occurs in 2.6 % of emergency cases and up to 12.2 % among patients with schizophrenia or bipolar disorder. With limited available options for effective management of acute agitation, ketamine is emerging as a fast-onset alternative to antipsychotics like haloperidol.

METHODS

This systematic review, following PRISMA guidelines, searched databases in April 2024 for studies on parenteral ketamine for acute agitation in emergency settings. Data extraction included patient demographics, ketamine administration details, sedation time, need for additional doses, adverse events, and intubation rates.

RESULTS

The search yielded 7410 results, narrowing to 29 suitable studies with 1516 patients (mean age 35.5 ± 12.4 years, 67.9 % male). Ketamine was administered intramuscularly (IM) in 69 % of studies, intravenously (IV) in 6.9 %, and either IV or IM in 24.1 %. Most patients (86.5 %) received IM ketamine at a mean dose of 3.83 ± 1.07 mg/kg, while 13.5 % received IV ketamine at 2.09 ± 1.56 mg/kg. Sedation occurred on average in 6.1 min. However, 24.5 % needed rescue medications or additional doses. Adverse effects included tachycardia (5.1 %), hypertension (5.5 %), hypersalivation (5.6 %), nausea (2.1 %), emergence reactions (1.4 %), and, rarely, cardiac arrest (0.2). While 19.1 % required intubation, the reasons for the same could not be attributed to ketamine exclusively. Furthermore, there was no evidence for worsening or development of psychotic symptoms with ketamine.

CONCLUSION

This review highlights the effectiveness and safety of parenteral ketamine for managing acute agitation in emergency settings. However, further research is needed to optimize ketamine use in this challenging scenario.

Fixed dose ketamine for prehospital management of hyperactive delirium with severe agitation

INTRODUCTION

Patients exhibiting signs of hyperactive delirium with severe agitation (HDSA) may require sedating medications for stabilization and safe transport to the hospital. Determining the patient's weight and calculating the correct weight-based dose may be challenging in an emergency. A fixed dose ketamine protocol is an alternative to the traditional weight-based administration, which may also reduce dosing errors. The objective of this study was to evaluate the frequency and characteristics of adverse events following pre-hospital ketamine administration for HDSA.

METHODS

Emergency Medical Services (EMS) records from four agencies were searched for prehospital ketamine administration. Cases were included if a 250 mg dose of ketamine was administered on standing order to an adult patient for clinical signs consistent with HDSA. Protocols allowed for a second 250 mg dose of ketamine if the first dose was not effective. Both the 250 mg initial dose and the total prehospital dose were analyzed for weight based dosing and adverse events.

RESULTS

Review of 132 cases revealed 60 cases that met inclusion criteria. Patients' median weight was 80 kg (range: 50-176 kg). No patients were intubated by EMS, one only requiring suction, three required respiratory support via bag valve mask (BVM). Six (10%) patients were intubated in the emergency department (ED) including the three (5%) supported by EMS via BVM, three (5%) others who were sedated further in the ED prior to requiring intubation. All six patients who were intubated were discharged from the hospital with a Cerebral Performance Category (CPC) 1 score. The weight-based dosing equivalent for the 250 mg initial dose (OR: 2.62, CI: 0.67-10.22) and the total prehospital dose, inclusive of the 12 patients that were administered a second dose, (OR: 0.74, CI: 0.27, 2.03), were not associated with the need for intubation.

CONCLUSION

The 250 mg fixed dose of ketamine was not >5 mg/kg weight-based dose equivalent for all patients in this study. Although a second 250 mg dose of ketamine was permitted under standing orders, only 12 (20%) of the patients were administered a second dose, none experienced an adverse event. This indicates that the 250 mg initial dose was effective for 80% of the patients. Four patients with prehospital adverse events likely related to the administration of ketamine were found. One required suction, three (5%) requiring BVM respiratory support by EMS were subsequently intubated upon arrival in the ED. All 60 patients were discharged from the hospital alive. Further research is needed to determine an optimal single administration dose for ketamine in patients exhibiting signs of HDSA, if employing a standardized fixed dose medication protocol streamlines administration, and if the fixed dose medication reduces the occurrence of dosage errors.

Association of Ketamine Dosing with Intubation and Other Adverse Events in Patients with Behavioral Emergencies

OBJECTIVE

Varying rates of complications have been reported for prehospital sedation with ketamine, and the relationship to dosing has not been studied on a large scale. We evaluated the association between prehospital ketamine dosing and rates of intubations and other adverse events in patients with behavioral emergencies.

METHODS

Using the 2018/2019 ESO public-use research datasets, we included all non-traumatic, adult behavioral and drug-related EMS encounters with ketamine administration. Based on consensus guidelines, we stratified patients into "above" and "at/below" the maximum dosing for sedation (2 mg/kg IV/IO or 5 mg/kg IM) using the highest single dose of ketamine given. We created propensity scores for matched subjects using 1:1 propensity score matching. Using logistic regression, we compared rates of intubation and other airway interventions, antipsychotic coadministration, improvement reported by EMS, hypoxia, hypotension, and cardiac arrest between the two groups.

RESULTS

We included 2383 patients: 478 in the above and 1905 in the at/below dose group. Above-dose ketamine was associated with a higher rate of intubation or supraglottic airway placement (6.4% v 3.3%, OR 2.0, 95% CI 1.00-3.90). Other airway interventions were similar (40.0% v 40.0%, OR 1, 95% CI 0.80-1.30). The above-dose group also showed a higher rate of improvement noted by EMS clinicians (92.5% v 88.7%, OR 1.6, 95% CI 1.01-2.40). The rates of antipsychotic coadministration, hypoxia, hypotension, and cardiac arrest were similar between the cohorts.

CONCLUSIONS

Patients given ketamine doses above consensus recommendations for sedation appeared more likely to receive prehospital intubation but not more likely to experience other adverse events.

A Comparison of Prehospital Pediatric Analgesic Use of Ketamine and Opioids

OBJECTIVE/INTRODUCTION

Ketamine is an opioid-alternative used for analgesia in the prehospital setting. There are knowledge gaps regarding its use during emergency medical services (EMS) encounters for pediatric patients. Our objective was to compare pain reduction, adverse events, and prehospital deaths between ketamine and opioids when used for analgesia administered by any route among pediatric patients.

METHODS

This was a retrospective review of 9-1-1 EMS records of injured pediatric patients (≤17 years of age) who received ketamine or opioids for analgesia using the ESO Data Collaborative (calendar years 2019-2020). We excluded interfacility transfers, patients receiving both medications, those with EMS clinician impressions indicating behavioral disorders, and those who received medication to facilitate advanced airway placement. EMS narrative review was performed to confirm ketamine use was for analgesia and to identify any unplanned airway placements. We assessed pain score reduction (0-10 ordinal scale) and clinician-documented patient response (improved, unchanged, worsened, unknown). Adverse events were defined as change in vital signs (GCS, SBP, RR, SpO2), bag valve mask ventilation alone, or death. Descriptive statistics were calculated to compare outcomes between groups.

RESULTS

Overall, 9,223 patients were included, 190 (2.1%) received ketamine and 9,033 (97.9%) received opioids. Mean age in years was 12.8 [SD 4.0] for ketamine and 12.7 [SD 4.0] for opioids. Patients in both groups experienced pain reduction, and more patients receiving ketamine had EMS clinician reported improvement (93.2% vs. 87.9%, p = 0.03). Ketamine was associated with a greater average reduction in pain score than opioids (mean difference: -4.4 [SD 3.5], and -3.1 [SD 2.8], p < 0.001). Adverse events were rare with few patients receiving ventilatory support following the use of ketamine or opioids, (0, [SD 0.0%] vs. 6 [SD 0.1%], p = 1). There were no unplanned airway placements or prehospital deaths identified.

CONCLUSION

We identified similar high rates of pain reduction and rare adverse events among pediatric patients who received ketamine or opioids. A greater pain reduction was noted among patients administered ketamine. Intubation as a result of medication administration did not occur and need for ventilatory assistance was rare.

Intubation Rates following Prehospital Administration of Ketamine for Acute Agitation: A Systematic Review and Meta-Analysis

BACKGROUND

Ketamine is a fast-acting, dissociative anesthetic with a favorable adverse effect profile that is effective for managing acute agitation as a chemical restraint in the prehospital and emergency department (ED) settings. However, some previously published individual studies have reported high intubation rates when ketamine was administered prehospitally.

OBJECTIVE

This systematic review aims to determine the rate and settings in which intubation following prehospital administration of ketamine for agitation is occurring, as well as associated indications and adverse events.

METHODS

We searched PubMed, Scopus, Ovid MEDLINE, Embase, CINAHL Plus, PsycINFO, the Cochrane Library, ClinicalTrials.gov, OpenGrey, Open Access Theses and Dissertation, and Google Scholar from the earliest possible date until 13/February/2022. Inclusion criteria required studies to describe agitated patients who received ketamine in the prehospital setting as a first-line drug to control acute agitation. Reference lists of appraised studies were screened for additional relevant articles. Study quality was assessed using the Newcastle-Ottawa quality assessment scale. Synthesis of results was completed via meta-analysis, and the GRADE tool was used for certainty assessment.

RESULTS

The search yielded 1466 unique records and abstracts, of which 50 full texts were reviewed, resulting in 18 being included in the analysis. All studies were observational in nature and 15 were from USA. There were 3476 patients in total, and the overall rate of intubation was 16% (95% confidence interval [CI] = 8%-26%). Most intubations occurred in the ED. Within the studies, the prehospital intubation rate ranged from 0% to 7.9% and the ED intubation rate ranged from 0 to 60%. The overall pooled prehospital intubation rate was 1% (95% CI = 0%-2%). The overall pooled ED intubation rate was 19% (95% CI = 11%-30%). The most common indications for intubation were for airway protection and respiratory depression/failure.

CONCLUSIONS

There is wide variation in intubation rates between and within studies. The majority of intubations performed following prehospital administration of ketamine for agitation took place in the ED.