Low Dose Ketamine for Acute Pain Control in the Emergency Department

Author: Makayla Smith

Article Review: Low-Dose Ketamine for Acute Pain Control in the Emergency Department

Citation: Balzer N, McLeod SL, Walsh C, Grewal K, Walia S. Low-dose ketamine for acute pain control in the emergency department: A systematic review and meta-analysis. Acad Emerg Med. 2021;28(4):444–454. PubMed ID: 33098707

Introduction

Pain management remains one of the most frequent and critical interventions in emergency medicine. Opioids carry well-known risks, including respiratory depression, hypotension, and potential for misuse. As the opioid epidemic continues, ED clinicians have sought effective, non-opioid alternatives that still provide rapid analgesia. Low-dose ketamine (LDK), typically administered at < 0.3 mg/kg IV, offers NMDA receptor antagonism without the dissociative or hallucinogenic effects seen at higher doses. This systematic review and meta-analysis evaluated whether LDK provides analgesia comparable to morphine in the ED, while assessing adverse event profiles.

Relevance to Emergency Medicine

• Pain is the #1 ED complaint, and optimizing rapid, safe analgesia is essential to patient satisfaction and flow.

• Opioid stewardship is a major quality metric and institutional priority.

• LDK offers an alternative that can be given quickly, even in patients with contraindications to opioids (e.g., hypotension, respiratory compromise, allergy, opioid tolerance).

• Evidence-based understanding of ketamine’s efficacy and safety directly informs ED analgesic protocols and multimodal pain pathways.

Study Design

Type: Systematic review and meta-analysis of randomized controlled trials (RCTs)

Population: Adult ED patients with acute pain of various etiologies

Intervention: Low-dose IV ketamine (< 0.3 mg/kg)

Comparator: IV morphine or standard opioid analgesia

Outcomes: Pain reduction, need for rescue analgesia, and adverse events (nausea, vomiting, hypoxia, etc.)

Data sources: MEDLINE, EMBASE, and reference lists through 2020

Quality assessment: GRADE methodology used to evaluate certainty of evidence

Methods

Eight RCTs were included, totaling 1,191 ED patients (598 ketamine vs. 593 morphine). Pain scores were standardized using 0–10 numeric rating scales at multiple time points. Random-effects meta-analysis was used to compare groups. Risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI) summarized pooled results. All outcomes were rated low certainty due to heterogeneity and study limitations.

Results / Key Findings

Analgesic Effectiveness:

• 0–60 minutes: No statistically significant difference in pain reduction between LDK and morphine.

• 60–120 minutes: Slight trend favoring morphine, but not clinically meaningful.

• Rescue analgesia: Similar rates (RR = 1.26; 95% CI = 0.50–3.16).

Adverse Events:

• Nausea/Vomiting: No difference (RR = 0.97; 95% CI = 0.63–1.49).

• Hypoxia: Lower with LDK (RR = 0.38; 95% CI = 0.10–1.41), suggesting a favorable respiratory profile.

• Dysphoria: Mild, self-limited, and infrequent in subdissociative doses.

Discussion

Low-dose ketamine provides analgesia comparable to morphine during the first hour of ED management, with a similar or better safety profile. While morphine may sustain pain relief slightly longer, ketamine’s rapid onset, hemodynamic stability, and lack of respiratory depression make it a valuable tool for opioid minimization.

Clinical implications:

• LDK can be used as first-line or adjunct analgesia for acute pain when opioids are undesirable.

• Typical ED dosing: 0.1–0.3 mg/kg IV (10–20 mg) over 10–15 minutes.

• Monitor for transient dizziness, dissociation, or nausea.

Limitations: Variability in dosing protocols and timing of assessments, small study sizes, and lack of long-term outcomes.

Conclusion

In the emergency department, low-dose ketamine is a safe, effective alternative to opioids for acute pain control, offering comparable short-term analgesia with potentially fewer respiratory risks. Current evidence supports LDK as an important component of multimodal analgesia protocols in emergency medicine.