EFFICACY OF KETAMINE-PROPOFOL COMBINATION FOR SHORT SURGICAL PROCEDURES

In recent years there has been particular interest in ketamine-propofol for sedation of patients who are candidates for short minimally invasive surgical procedures. In some centers in Canada and the U.S. is, in fact, the first choice of sedation in the ED. There are also publications of their usefulness for pediatric procedures, interventional radiology, hematology, oncology, neurosurgery, ophthalmology, orthopedic surgery, CABG, burn patients, gastroenterology, etc.; its benefits as mixed anesthetic technique in patients with neuraxial anesthesia are recognized. Around this, the literature is generous to provide us with evidence to use it in our daily practice.

There is no precise definition of what the ketofolis. Generally refers to the 50:50 mixture of ketamine and propofol, 0.5 mg / kg of each. However, a broader definition considered that ketofol is the combination of ketamine and propofol, regardless of the ratio to each other (the initial dose of each can be scaled up to 3 mg / kg). When they are used in infusion, the dose is 100μg/kg/min.

The combination of ketamine and propofol offers advantages from a theoretical viewpoint, and as already shown, from a clinical standpoint. Ketamine-propofol technique simulates the conditions of general anesthesia because the patient is still unconscious, and although they should be available for when needed, saves anesthetic equipment as endotracheal tubes, laryngeal masks, anesthesia machine, etcetera. Avoid also the risk of malignant hyperthermia by halogenated because the patient is not exposed to pure technical inhalation or balanced techniques. Guitar proposed the ketamine-propofol mixture in 1991, however, was Friedberg who first published his benefits March 26, 1992. Friedberg was based on the technique of Vinnik using ketamine-diazepam for outpatient cosmetic procedures performed in the office. Ketamine is an aryl cyclohexamine (2-0-chlorophenyl-2-methylamino cyclohexanone) synthesized in 1961, with sedative, amnesic and analgesic properties, acting as NMDA receptor antagonist and agonist μ and σ opioid receptors. It starts to act at the first minute after intravenous application. Its duration of action is 15-30 min intravenously; the elimination half-life is 2-3 hours. Is soluble in water and lipophilic, which allows its administration by multiple routes. At low doses is primarily an analgesic and mild sedative, at higher doses produced a catatonic dissociated state which level of sedation is not increased with subsequent doses. Ketamine should be dosed based on ideal body weight and infused in 1 to 2 minutes.

It has been used extensively in health institutions with limitations for patient monitoring or limitations to address advanced airway devices, because it preserves airway reflexes, indeed, patients can swallow even if they are completely dissociated. Ketamine also increases blood pressure and myocardial oxygen demand by stimulating the cardiovascular tone by inhibiting the reuptake of catecholamines centrally. Ketamine is a respiratory stimulant, but may cause transient respiratory depression and even apnea during the first 3 minutes of administration. This problem is most often observed when the drug is administered rapidly or in association with other respiratory depressants such as benzodiazepines. It also produced laryngospasm in 0.4% of a large series of patients, so initially was contraindicated for intraoral procedures, but today it is still used for dental procedures.

Of the 11,589 children in the meta-analysis of Green who were administered ketamine, only 2 (0.017%) required intubation for laryngospasm. Other adverse effects of ketamine include feelings of dissociation from the body, unpleasant dreams, hallucinations or illusions, delusions, etc. Produces electrophysiological dissociation between neocortex, thalamus and limbic system, stimulation of the hippocampus and other subcortical nuclei, or the depression of the visual and auditory nuclei, which would lead to the misperception of external stimuli.