Welcome to UH EMS Institute’s Pharmacy Phriday. In this installment we focus on the use of ketamine within the UH protocols.
Ketamine is in a class of medications that are referred to as dissociative anesthetics. It is used in the prehospital setting for sedation and pain management, which can cause a state of sedation along with an amnestic effect. At lower doses, ketamine can provide an analgesic effect without the dissociative state. These doses are referred to as the sub-dissociative dose of ketamine.
A dissociative state is where the patient is separated from conscious awareness and their environment. It is thought to be caused by an interruption of neural transmission to parts of the brain, and therefore produces anesthesia characterized by loss of short-term memory (amnesia), inability to feel pain (analgesia), and a decreased sensitivity to pain (catalepsy). The goal of the dissociative state when administering the high dose of ketamine is sedation, where a patient will often stare off as if the “lights are on, but no one is home,” who does not react to any stimuli, but still maintains or preserves spontaneous respirations, airway reflexes, and remains hemodynamically stable.
Ketamine could be found within the UH protocols for pain management, airway procedures, rapid sequence intubation (RSI), ongoing sedation (required after placing an advanced airway), behavioral/psychiatric emergencies, and in situations of CPR-induced consciousness (CPRIC).
Under UH protocols, ketamine’s use in the pediatric patient is limited to behavioral emergencies and then only for those older than 16 years of age and over 50 kg in weight. AEMTs can administer ketamine for pain and CPRIC, and in cases of the agitated or combative patient, with prior approval and training.
For specific dosing ranges of ketamine, see the chart below.
Ketamine can have many side effects that may include:
•Apnea
•Hallucinations and vivid dreams
•Hypertension
•Increased cardiac output
•Laryngospasm
•Myocardial depression
•Salivation
•Tachycardia
•Tonic-clonic movements (not seizures)
These and other possible side effects require monitoring of the patient’s vitals, respiratory rate and effort, EKG, capnography, etc.
Ketamine can also cause an emergence reaction. This is a syndrome of confusion, excitement, irrational behavior, and hallucinations that a patient may experience after getting ketamine and may occur as the patient is starting to wake up (usually about 30 minutes after administration). In most areas, this would typically be seen in the ER setting. It occurs as the patient begins to metabolize the ketamine and enters a partial dissociative state, becoming more aware of their surroundings and that something is not right. Treatment for such reactions includes the use of a benzodiazepine.
Be sure to document the use of ketamine thoroughly. Within the UH system, all ketamine administrations are reviewed by our medical directors for the following minimum items:
•Was the medication administration appropriate?
•Did the ketamine administration cause harm or potential harm to the patient?
•Was a blood glucose reading obtained?
•Was capnography applied?
•Was a monitor applied?
•Was a response to the medication documented?
Some additional precautions and points to remember when administering ketamine include:
•Rapid IV injection can result in transient apnea. Ketamine should be administered slowly over at least a 1-minute period.
•To administer low-dose ketamine for pain, the provider must dilute the 100 mg/ml concentration to 10 mg/ml. This can be accomplished by using a 10 ml syringe, drawing 9 ml of NS and 1 ml of the 100 mg/ml ketamine and mixing the new solution.
•Providers administering ketamine should be prepared to provide supplemental oxygen and secure the airway.
•The risk of ketamine use during pregnancy is documented and it is often recommended the provider consult medical direction prior to administration.
Until next week’s Pharmacy Phriday, stay safe!!
