Three Regimens of Ketamine Infusion in Complex Regional Pain Syndrome

Phase 4

Recruiting

Brief Summary: To evaluate the efficacy of three regimens of sub anesthetic dose of ketamine infusion in relieving chronic refractory pain in patients with complex regional pain syndrome

Detailed Description: Ketamine N-methyl-D-aspartate (NMDA) receptor blocker that has recently been studied for its analgesic effect is a phencyclidine or phenyl cyclohexyl piperidine (PCP) derivative that initially became commercially available for human use in 1970 as a rapid-acting intravenous (IV) anesthetic. It is currently classified by the Food and Drug Administration (FDA) as an anesthetic induction agent in doses ranging from 1 to 4.5 mg/kg.

Ketamine has proven to be a desirable drug, despite of its induction dissociative effects and abuse potential. It is favorable due to its short half-life and lack of clinically significant respiratory depression. In addition to its anesthetic effects, ketamine has analgesic, anti-inflammatory, and antidepressant activities.

Recruitment & Eligibility

Inclusion Criteria

Patients aged more than 21 years old of both sexes with American Standards Association I ,II.
Patients diagnosed as ( CRPS) based on Budapest criteria
The average daily pain intensity required on (NRS) is 7 or more for at least 3 months despite of standard therapy which includes: (pharmacologic therapy as non steroidal anti- inflammatory drugs (NSAIDs), antiepileptic (AEDs), antidepressants), as well as physical therapy and psychiatric care

Exclusion Criteria

patients refusal
Patients with unstable psychological or psychiatric conditions, including : untreated bipolar disorder, post-traumatic stress disorder, major depression , severe personality disorder and psychotic illness.
Patients have recently undergone major interventional pain procedures, such as nerve blocks or implantable therapies within 3 months of enrollment.
Patients with known drug dependency or substance use disorder specifically related to ketamine or other psycho-stimulant drugs.
Patients with previous severe reactions, contraindication or allergy to ketamine.
Patients with cardiovascular disease (hypertension, arrhythmia), hepatic, renal or other organ impairment.

Arm && Interventions

Group	Intervention	Description
Group A	Ketamine	patients will receive ketamine parenteral infusion (0.35 mg/kg/h or maximum 24mg/h) at post anesthetic care unit(PACU) over 6 hours for 3days
Group B	Ketamine	patients will receive ketamine parenteral infusion (0.35 mg/kg/h or maximum 24mg/h ) at post anesthetic care unit(PACU) over 6 hours for 5 days .
Group C	Ketamine	patients will receive ketamine parenteral infusion (0.35 mg/kg/h or maximum 24mg/h ) at post anesthetic care unit(PACU) over 6 hours for 7 days

Primary Outcome Measures

Name	Time	Method
degree of chronic pain reduction	up to 3 months post infusion	using Brief Pain Inventory short form (BPI-SF) questionnaire. It is a 9 item self-administered questionnaire used to evaluate the severity of a patient's pain and the impact of this pain on the patient's daily functioning. The patient is asked to rate their worst, least, average, and current pain intensity, list current treatments and their perceived effectiveness, and rate the degree that pain interferes with general activity, mood, walking ability, normal work, relations with other persons, sleep, and enjoyment of life on a 10 point scale.

Secondary Outcome Measures

Name	Time	Method
Side effects	up to 3 months post infusion	Headache, Nausea and vomiting
Reduction of the degree of chronic pain score	up to 3 months post infusion	Numerical rating scales (NRS) is an 11-point scale for patient self-reporting of pain. It is based solely on the ability to perform activities of daily living (ADLs) with 0 being "no pain" and 10 being "the worst pain imaginable"

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