Low-dose KETamine as an Adjunct to MOrphine for Acute Pain in the ED

Inclusion Criteria: 1. Emergency Department admission 2. Age ≥ 18 years 3. NRS ≥ 5 4. Stable vital signs defined as systolic blood pressure ≥ 90 mmHg, heart rate between 60 and 150 per minute, respiratory rate between 8 and 26 per minute, oxygen saturation greater than or equal to 92% Exclusion Criteria: 1. Initial management by trauma-team 2. Systolic blood pressure ≥ 180mmHg, severe untreated arrhythmia, unstable angina, recent myocardial infarction (\< 30 days), severe heart-failure (Ejection fraction \< 40 %) 3. Symptoms of untreated hyperthyroidism 4. Cirrhosis with ascites 5. Known/suspected pregnancy or breastfeeding 6. Patients for whom consent is not obtainable or psychiatric forced treatment. 7. Previously enrolled in the trial 8. Psychiatric illness prior to admission defined as prior psychosis/schizophrenia 9. Untreated diagnosed glaucoma 10. Known hypersensitivity to ketamine or to any excipient or prior use of ketamine with a negative experience (i.e. hallucinations) 11. Patient clearly influenced by drugs or alcohol