Ketamine for Induction Use in the Prehospital Setting Background • Multiple drug shortages are threatening the safe management of the most critically ill and injured patients. • Critical drugs such as etomidate, midazolam and diazepam have at times not been available to some of our EMS agencies. Why Ketamine? • Ketamine has long been used for procedural sedation in the emergency department. • More recently, concerns have been raised regarding possible negative effects of adrenal suppression in septic patients intubated using etomidate. • Therefore, several studies as well as discussions in the literature have since favorably reviewed the use of ketamine for induction. Mechanism of Action • Ketamine is a dissociative anesthetic agent, structurally similar to phencyclidine (PCP), which interrupts the connection between the cortex and the limbic system. • Stimulates opiod receptors and is thus a unique sedative agent in that it provides analgesia as well. • Stimulates catecholamine release • Increased BP, HR and cardiac output • Bronchodilatation Pharmacokinetics • Onset of anesthesia when given IV is 30 to 60 seconds. • The duration of the anesthetic effect is 5 to 10 minutes when given IV. • The duration of drug effect following IV dosing can last for hours. In this phase, the patient is responsive but has varying degrees of delirium. Indications • Induction agent for rapid sequence intubation (RSI) • At this time, ketamine should only be used as an induction agent when the supplies of etomidate have been exhausted. • It is also used for procedural sedation and analgesia, however it will not be approved for these uses by EMS. Precautions • Ketamine should be used with caution in patients with elevated blood pressures. • Do not use ketamine in patients who may be in a hypertensive crisis • Patients emerging from the effects of ketamine may experience disturbing nightmares and hallucinations. Be sure to continue sedation after they are intubated with another sedative agent. Precautions • May cause increased intraocular pressure and should not be used when globe rupture is a concern. • Increased ICP: This is controversial as several studies have shown minimal increase in ICP. In fact, an increase in CPP may actually be beneficial. However, when increased ICP is suspected, it may be beneficial to concomitantly give a dose of midazolam 2 to 4 mg. Drug Interactions • There are no major drug interactions to avoid Dosing • The general induction dose is 2 mg/kg • A range of 1 to 2 mg/kg is provided to allow for a decrease in dose at the discretion of the medic, such as in elderly patients.