It's Time for EMS to Administer Ketamine Analgesia

Management of severe pain in the prehospital setting has been a controversial topic since the development of the organized delivery of prehospital emergency care. Concerns regarding adverse effects from opioid administration such as respiratory depression and hypotension, as well as concerns about symptom masking impeding physician examination, have led to systemic prehospital oligoanalgesia. Despite a 2003 evidence-based position paper from the National Association of EMS Physicians (NAEMSP) emphasizing the importance of adequate pain management, multiple subsequent studies have demonstrated the ongoing existence of prehospital oligoanalgesia.^1–5

Morphine has been the primary opioid analgesic available for prehospital use in the United States dating back to the Civil War. As early as World War II, however, concerns began surfacing regarding sequelae when morphine is administered to trauma patients.⁶ Fentanyl, an opioid with a wider safety profile than morphine, was introduced into some prehospital formularies, but other pharmacologic options need to be explored. Many current civilian EMS protocols, such as early tourniquet application, have been adapted from military practice; it is time to make ketamine analgesia a more widespread addition to that list, as presently only a limited number of leading edge EMS systems allow the use of ketamine by Advanced Life Support level providers for analgesia.⁷

Initial experience in the United States military was limited to Special Operations medical providers with an expanded scope of practice. Ketamine has proven remarkably versatile; it can be used as a standalone analgesic or given alongside either opioids or benzodiazepines for a synergistic effect.^8,9 Indeed, many now refer to ketamine as the Swiss Army Knife for subanesthetic application.¹⁰

In 2012 the Defense Health Board approved the use of ketamine for prehospital analgesia across the Department of Defense (DoD) in accordance with Tactical Combat Casualty Care (TCCC) guidelines.^11,12 Most DoD published experience with prehospital ketamine analgesia is focused on case studies, but the safety profile is nevertheless impressive with minimal reported complications. The analgesia update to the TCCC guidelines provides an excellent review of the available literature on the topic.¹³

In a series of military and civilian studies, ketamine was compared to a variety of opioid analgesics including the previous gold standard of morphine, the increasingly widely used fentanyl, and in one study pentazocine. In each case ketamine provided equally effective pain relief as the opioid agents.^14–16 Additionally, whereas opiates can cause hypotension, ketamine both stimulates catecholamine release and inhibits their reuptake, often causing an increase in blood pressure.¹⁵

These properties open a new frontier in prehospital analgesia, as there traditionally have been limited options for prehospital pain management of the hypotensive, hemorrhaging patient. Ketamine is not restricted to managing pain in traumatic cases of hemorrhage either. It is also appropriate for patients whose pain and hemorrhage are secondary to medical etiology.

Civilian hospital-based literature and military research both demonstrate the wide safety profile for ketamine. Anecdotal overdoses of 100 times the intended dose have been reported with no long-term sequelae.¹⁷ Ketamine also does not have the respiratory depressant effects that many opioids do.¹⁵ These additional properties make ketamine an ideal choice for analgesia for virtually all indications.

Ketamine has historically been considered to have two major drawbacks.The most famous of these is the specter of emergence reactions. The American College of Emergency Physicians (ACEP) discourages ketamine use in patients with any psychosis history based on evidence showing that ketamine precipitates psychotic episodes in patients with schizophrenia.^18,19 Among patients without such history, however, clinically significant emergence reactions occur in less than 2% of pediatric patients.²⁰ For adults, the incidence ranges from 0 to 30%.When emergence reactions do occur, administration of a benzodiazepine provides simple resolution without sequelae.¹⁹

The other reservation about ketamine use is the risk that it could precipitate an increase in intracranial pressure (ICP). Recent research has demonstrated that this concern is unfounded, and ACEP has endorsed the use of ketamine in patients with traumatic brain injury (TBI).^19,21 Indeed, there is now emerging literature examining TBI/ICP instances where Ketamine is showing a potential neuro protective effect.²² Ketamine's effect on intraocular pressure is less clear, however, and ACEP considers open globe injury a relative contraindication for ketamine use.^19,23,24

Extreme caution should also be exercised in patients experiencing a hypertensive crisis or ischemic chest pain, as they are likely to be intolerant of a sudden increase in blood pressure. These patients would be better served by an opioid analgesic that will not increase cardiac workload.^19,25

While ketamine is indeed an ideal analgesic under virtually all conditions, in order to provide optimal patient care it should not be the sole medication available. Field providers should have the option to use an opioid such as fentanyl in lieu of ketamine for a severely hypertensive patient or one with a known psychosis history. It would also be wise to have a benzodiazepine available to treat emergence reactions if one occurs.

At the moment, ketamine is only United States Food and Drug Administration (FDA)-approved for use in general anesthesia and procedural sedation. NAEMSP takes the official position, however, that medical directors may authorize any legal medication for off-label use.²⁶ Such treatment protocols are widely accepted in EMS and include nasal naloxone administration, administration of sublingual nitroglycerin to patients with early myocardial infarctions, and administration of glucagon to counteract beta blocker overdoses.^27–29

Three questions must be answered before adding a new medication to an EMS service's drug formulary or expanding the indications for a drug currently being carried:

• Does it work?

• Does it offer an advantage over what is currently on the market?

• Is it safe?

For ketamine analgesia, the answer to all three questions is yes.