Ketamine is a drug with multiple applications used in medical procedures with humans and subsequently adopted for veterinary medicine, mainly for starting and maintaining general anesthesia. Other uses include sedation in intensive care, as a pain killer (particularly in emergency medicine and patients with potentially compromised respiration and/or allergies to opiate and barbiturate analgesics), and as treatment of bronchospasm, and as a treatment for complex regional pain syndrome. It is on the World Health Organization's List of Essential Medicines, a list of essential medicines that should be available in a health system. Its usage as a recreational drug has resulted in several high profile deaths.