The Incidence of Psychic Effect using Ketamine and Versed in Outpatient Anesthesia

Background/Overview and Objective:   Anesthetic technique in the outpatient setting is an art based in science. There are a great number of pharmaceutical agents available to us that can be used singularly or in combination to create a safe and effective anesthetic experience.   However, it appears that many practitioners tend to avoid the use of Ketamine in procedural sedation, particularly with adults,  despite its long history of safety producing effective  analgesia, amnesia, and sedation ¹: This is  owed to concern of ketamine producing undesirable delirium and agitation, an uncommon phenomenon when co-administered with Versed ^{1 2}. This retrospective and prospective study aims to demonstrate that Ketamine, when administered with Versed, produces a safe and effective procedural sedation without significantly increasing the risk of untoward psychic effects. This is done in hope that practitioners will be more confident in using this medication for procedural sedation, particularly in cases where Ketamine can be particularly well suited given certain patient medical history.   

 Methodology: Retrospective chart review was performed on all intravenous procedural sedations in the Department of Oral and Maxillofacial Surgery at Bellevue Medical Center Hospitals from January 2012 to present.  Cases selected for inclusion into the study were those where Versed and Ketamine were the sole intravenous anesthetic agents used†. Nursing staff’s documentation of RASS scores intraoperatively and postoperatively at 5 minute intervals were assessed.  Any record that documented an Intra- or Post- operative RASS score above 0 occurring after an administration of ketamine were labeled as an adverse anesthetic reaction. Those cases where the anesthetic record failed to document a RASS score intra- or post-operatively were excluded from analysis. Patient's age, sex, home medications, and total dosages of ketamine and versed were also noted for statistical inference.  It is the intent to continue this methodology for future prospective data collection as well.

Results:  43 anesthetic cases met initial criteria for inclusion. Of those 43, 5 cases were removed due to inadequate anesthetic documentation. The remaining 38 cases for analysis show: a 1:1 male to female distribution, 17 were under 21 years of age (average 21.5 years).  Of the remaining 38 cases meeting criteria for analysis showed 7 cases where the patient was noted to have an adverse anesthetic event. Of the 7 cases where an adverse event was noted; 4 of the patients were female, 4 were over 21 years of age, 1 of the patients was taking baseline home mood altering medications, 6 received a ketamine dose greater than or equal to 25mg, and 1 received less than 2mg of midazolam.   

Conclusions:  There appears to be minimal risk of encountering adverse psychic effect after administration of ketamine with versed in procedural sedation from our sample based on assessment of intraoperative and postoperative RASS scores. The risk of encountering an adverse effect shows slight predilection towards females and those over 21 years old. Ketamine dosages higher than 25mg and Versed doses less than 2 mg  appear to increase the risk of having an adverse effect. Future prospective collection will further impact conclusions from the retrospective analysis.

Future research:  Randomized controlled studies that compare the incidence of psychic effect with ketamine as a sole agent, and ketamine with other agents in combination.

References:

1: Sener S et al. Ketamine With and Without Midazolam for Emergency Department Sedation in Adults: A Randomized Controlled Trial. Ann Emerg Med. 2011;57:109.

2: Strayer RJ and Nelson LS. Adverse events associated with ketamine for procedural sedation in adults. American Journal of Emergency Medicine, Volume 26 Issue 9, November 2008, pages 985-1028.

†: Procedural sedations all took place with Nitrous Oxide/Oxygen inhalational anesthesia. Remaining agents given Intravenously