Three Regimens of Ketamine Infusion in Complex Regional Pain Syndrome

Assessment of Three Regimens of Ketamine Infusion in Complex Regional Pain Syndrome: Randomized Prospective Comparative Study

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

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.

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.