Actions and Use of Ketamine in Disaster and Trauma Patients

Authors: Clinton Kakazu, M.D.; Maurice Lippmann, M.D.

ASA Monitor 03 2016, Vol.80, 50.

The December 2015 ASA Monitor features an article written by Uday Jain, M.D., which discusses the problem of anesthesia in disaster or an austere environment.¹  Disasters can produce multiple trauma victims, all of whom may be problematic to anesthesiologists who work to ensure these patients’ survival.

In the article, Dr. Jain mentions essential supplies and equipment, and discusses the proper use of anesthetic agents and analgesics, as well as different anesthetic techniques (i.e., general versus regional). Dr. Jain states that ketamine can be given to relieve pain. Many anesthesiologists administer ketamine in trauma and disaster patients because of its ability to maintain hemodynamic stability. However, many anesthesiologists may not realize that ketamine can work in the opposite fashion and endanger patients. We wish to point out the downside that ketamine poses in disaster and trauma patients.

It is not entirely correct to infer that the cardiovascular system is supported with the administration of ketamine in the treatment of hypovolemic battle and disaster casualties. In addition, using ketamine as an induction agent in these patients does not always prevent drops in blood pressure after induction. We do not want readers to be misled. Ketamine induction can cause hypotension, and not hypertension, in hypovolemic and debilitated high-risk patients, including trauma and disaster cases. Naturally, a beneficial induction goal in hypovolemic battle and disaster casualties would be to maintain or increase blood pressure. It goes without saying that this objective is not always achieved. Profound hypotension with reduced cardiac output does occur due to ketamine’s direct myocardial depressant effect. Anesthesiologists should be aware of the complication whenever ketamine is used.² 

The use of benzodiazepines to attenuate postoperative ketamine-induced mental abnormalities and provide amnesia is well-known.³ Use of this type of drug (diazepam or midazolam) in elective healthy individuals is one thing, but in battle and disaster causalities, this use could lead to increased morbidity and mortality. Diazepam may cause a fall in arterial blood pressure. Midazolam, which is more potent, can cause significant ventilatory depression. Furthermore, using midazolam may cause hypotension in severely wounded battle and disaster casualties. Thus, using benzodiazepines to treat or prevent ketamine’s postoperative hallucinations should be carefully considered.⁴ 

Ketamine may not be the preferred agent to use in the severely septic patient. Although the drug can increase sympathetic tone, causing blood pressure and heart rate to increase by releasing catecholamines, this effect is not always reliable. While ketamine increases tissue and circulating norepinephrine levels by decreasing their neuronal and extra neuronal re-uptake, another mechanism of ketamine’s action includes stimulation of the adrenocortical response. This action of ketamine is evidenced by increased serum cortisol levels post-administration. In severe trauma patients who are in hypovolemic shock and severely stressed, there is a possibility that catecholamine and adrenocortical levels may be depleted before the agent is administered.⁵  The same is true in those patients with severe sepsis; without the expected release of catecholamines, ketamine use in these patients can lead to profound hypotension. Thus, there is variability in ketamine’s action, which is determined by a balance between its direct myocardial depressant effect and its stimulatory sympathomimetic action.

Many anesthesiologists and surgeons feel that ketamine always performs in a “positive” way to improve or at least maintain a patient’s hemodynamic profile. They may not recognize the unanticipated adverse effects of even small doses of ketamine. Ketamine’s “negative” cardiovascular effect is not uncommon in this subset of patients (i.e., septic and critically ill). Our take-home message is this: Use caution and do not always rely on ketamine to increase heart rate and blood pressure. As professionals providing care to trauma and disaster patients, we cannot afford to overlook these potential downsides of ketamine.

References:

Jain U Anesthesia for disasters and austere environment. ASA Monit.2015;79(12):28–30.

Lippmann M, Hsu D . The use of ketamine in civilian and military surgery.Anaesthesia. 1989;44(6):533–534.

Strayer RJ, Nelson LS . Adverse events associated with ketamine for procedural sedation in adults. Am J Emerg Med. 2008;26(9): 985–1028.

Lippmann M, Hsu D . The use of Ketamine in civilian and military surgery.Anaesthesia. 1989;44(6):533–534.

Lippmann M, Karnwal A, Julka IS . Cardiovascular effects of ketamine in sick patients: should physicians be concerned? J Clin Pharmacol. 2010;50(4):482.