Author: Ethan Covey
The combination of dexmedetomidine (DEX) and ketamine in pediatric patients with normal airways and no history of obstructive sleep apnea (OSA) has no statistically significant effect on the caliber of the upper airway. The study reaffirms the safety and efficacy of these two medications in combination as anesthesia.
“Dexmedetomidine is already widely used for anesthesia/sedation due to its favorable characteristics on the airway, which include preservation of respiratory drive and minimal impact on airway caliber, leading to less airway obstruction than other anesthetic agents,” said Michale S. Ok, MD, an assistant professor in the Department of Anesthesia at Cincinnati Children’s Hospital Medical Center. “The analgesia provided with dexmedetomidine is limited, and this prevents it from being used as a single agent for painful or highly stimulating procedures, such as a drug-induced sleep endoscopy [DISE].”
“Each medication’s side effects can be abated by the effects of the other agent, and this may lead to a hemodynamically stable anesthetic that provides strong analgesia while maintaining favorable airway properties,” Dr. Ok added.
“There are already studies that confirm that both dexmedetomidine and ketamine have minimal impact on airway configuration in children individually,” Dr. Ok said. “In theory, this would seem to suggest that the two drugs in combination should still produce small changes to the airway. However, medications can sometimes produce synergistic effects and not additive effects, so we thought that it was important to examine this topic by studying children with normal airways first.”
No Effect at All?
The team of researchers studied 22 children, aged 4.9±3.6 years, with no history of OSA who presented for MRI of the brain and spine.
Patients were given a DEX bolus of 2 mcg/kg, followed by an hourly infusion of 2 mcg/kg. Cine images of the airway were acquired as a baseline. A ketamine bolus of 2 mg/kg was then given, and imaging was repeated after five, 10 and 15 minutes. The researchers obtained a total of approximately 72 images axial to the airway, and measured the cross-sectional area, transverse and anterior/posterior of the airway. Measurements were averaged for DEX and compared with the DEX and ketamine combination.
Although changes in upper airway caliber were noted with a DEX and ketamine combination, they were small in absolute magnitude and clinically insignificant.
“The study is significant in that we actually measured airway dimensions by MRI in spontaneously breathing patients with no manual assistance and confirmed that there was minimal difference in airway caliber when patients received ketamine after DEX,” Dr. Ok said.
An Important Finding for Therapy
“We observed that none of our pediatric patients needed intervention of the anesthesiologist for hemodynamic derangements, and there were no patients that had any significant movement during the MRI study,” Dr. Ok added. “Our surgeons who perform DISE want an anesthetic that is not going to significantly alter airway dynamics during the study of the airway. This has important implications because the findings during DISE may alter management decisions for patients with OSA.”
Dr. Ok noted that this study will be used to design and plan a future prospective study that will examine this anesthetic regimen’s effect on patients with OSA.
Additionally, the team would like to investigate potential effects of dose dependence between patients. “During our current study, we used fixed doses of DEX and ketamine on a per-kilogram basis,” Dr. Ok said. “Dose-dependent effects on the airway should be further studied to better characterize the effective dose while minimizing side effects.”
The research was presented at the 2019 annual meeting of the Society for Pediatric Anesthesia/American Academy of Pediatrics.