Ketamine and Refractory Painful Care in a Palliative Unit

Pain is one of the major symptoms in palliative care units and often is very difficult to treat, being considered as a refractory pain.

There are different causes of refractory pain: pain due to bed sores and ulcer bandages, carcinological or ischemic wounds or injuries, pain due to patients' reduced mobility, pain due to traumatological injuries, pain associated with a long-term bed confinement, etc.

The investigators propose a prospective study to estimate the effect and the tolerance to a subcutaneous bolus of ketamine administered for the treatment of refractory pain due to the care of bedsores, ulcers and vascular wounds in patients hospitalized in palliative care units.

Patients in palliative care units have serious and incurable conditions and are in the sickness' late or final stages. This is why the relief of their symptoms is a priority for their medical care, being pain one of the major symptoms.

In this context, the idea of treating various types of pain such as pain due to bed sore and ulcer bandages, carcinological or ischemic wounds or injuries, pain due to patients' reduced mobility, etc. was raised.

French Ministry of Health's 2010 recommends the use of ketamine to treat refractory pain after the failure of usual therapeutic treatments (opioids, Nitrous oxide and oxygen (also known as MEOPA)). This treatment is then used in association with midazolam (0.01 to 0.05 mg/kg) to prevent hallucinating effects.

However, the intravenous treatment is often the alternative and this choice is justified by the study population's characteristics (usually elderly patients, multi-pathologic, etc) and by the invasive way of treatment used with a repeated central and peripheral venous catheters which is contrary to the primary objective of patient comfort.

To the investigators' knowledge, no randomised study has ever been done regarding the use of ketamine to treat refractory pain administered subcutaneously.

Eligibility Criteria:
Inclusion Criteria:

* Patients of ≥18 years old, hospitalized in palliative care units
* Conscious or presenting altered/disturbed consciousness but for whom the Rudkin score is ≤ 4 (eyes closed, response to light tactical stimulation)
* For whom a palliative care is acted
* No matter the progression and prognostic status
* After the information is given to the patient (with the notification form given) and the written consent form is retrieved and when the state of cognition and vigilance allows it. In case of cognitive and consciousness disturbance, after informing and retrieving the written consent form from the patient's trusted person, or a relative by default, for patients under guardianship after being informed and giving a consent form written by the legal representative.
* Evened out on an analgesia level, without care
* Who has not received ketamine for 60 days before inclusion no matter the indications
* For whom bedsore, ulcer or vascular injuries have appeared and continue to be painful despite the administration of opioid bolus with the painful evaluation regarding the visual analogic scale (EVA) ≥ 5/10, or regarding the evaluation of the Algoplus pain behavior scale ≥ 2, or for whom the opioid treatment cannot be administered due to the presence of adverse side effects (drowsiness, confusion, nausea, vomiting, respiratory depression...)
* And for whom caring under Entonox (a medical analgesic gas which is a mix of nitrous oxide and oxygen) is inefficient or not compatible.
* Lack of easy venous access

Exclusion Criteria:

* Contraindication of Ketamine in case of anesthesia (AMM) : allergy, porphyria
* Late stage heart failure
* Intracranial hypertension
* Acute heart attack phase
* Unstable psychosis
* Presence of agitation
* Pregnant woman
* Patient with no affiliation to a social security system
* Contraindication of Midazolam: known hypersensitivity to benzodiazepines or any other know excipient of the product, acute respiratory depression