Upper‐airway collapsibility and compensatory responses under moderate sedation with ketamine, dexmedetomidine, and propofol in healthy volunteers

Abstract

Background: Ketamine is a potent sedative drug that helps to maintain upper-airway patency, due to its higher upper-airway dilator muscular activity and higher level of duty cycle, as seen in rats. However, no clinical trials have tested passive upper-airway collapsibility and changes in the inspiratory duty cycle against partial upper-airway obstruction in humans. The present study evaluated both the passive mechanical upper-airway collapsibility and compensatory response against acute partial upperairway obstruction using three different sedative drugs in a crossover trial. Methods: Eight male volunteers entered this nonblinded, randomized crossover study. Upper-airway collapsibility (passive critical closing pressure) and inspiratory duty cycle were measured under moderate sedation with ketamine, propofol, and dexmedetomidine. Propofol, dexmedetomidine, and ketamine anesthesia were induced to obtain adequate, same-level sedation, with a BIS value of 50-70 and the OAA/S score of 2-3 and RASS score of −3. Results: The median passive critical closing pressure of 0.08 [−5.51 to 1.20] cm H 2 O was not significantly different compared to that of propofol sedation (−0.32 [−1.41 to −0.19] cm H 2 O) and of dexmedetomidine sedation (−0.28 [−0.95 to −0.03] cm H 2 O) (p = .045). The median passive R US for ketamine 54.35 [32.00 to 117.50] cm H 2 O/L/s was significantly higher than that for propofol 5.50 [2.475 to 19.60] cm H 2 O/L/s; (mean difference, 27.50; 95% CI 9.17 to 45.83) (p = .009) and for dexmedetomidine 19.25 [4.125 to 22.05] cm H 2 O/L/s; (mean difference, 22.88;95% CI 4.67 to 41.09) (p = .021). The inspiratory duty cycle increased significantly as the inspiratory airflow decreased in passive conditions for each sedative drug, but behavior differed among the three sedative drugs. Conclusion: Our findings demonstrate that ketamine sedation may have an advantage of both maintained passive upper-airway collapsibility and a compensatory respiratory response, due to both increase in neuromuscular activity and the increased duty cycle, to acute partial upper-airway obstruction.

Ultrasound measurements for evaluation of changes in upper airway during anaesthesia induction and prediction difficult laryngoscopy: a prospective observational study

“…This study indicated that it was relatively simple to identify the different airway structures with the ultrasound image. We also found that the propensity for the upper airway to collapse after muscular relaxation obtained by ultrasound was consistent with previous studies 4, 29 , and similar to Simons JC 30 , this collapsibility of airway after induction of anaesthesia was stable. In all of these studies, the authors observed upper airway closing pressure (P CLOSE ) and genioglossus muscle electromyography to endpoints [29][30][31] , while we visibly recorded changes of upper airway before and after anaesthesia induction by ultrasound device, it might show a high degree of accuracy by "your eyes".…”

Evaluation of the Efficacy of Propofol-Magnesium Sulfate Combination for Sedation in Paediatric Magnetic Resonance Imaging of Brain.- a Randomized Controlled Trial

“…[1,7] Deep sedation is always associated with upper airway obstruction. [8] All these airway related complications can be prevented by giving general anaesthesia (GA) with…”

“…[2,7] However it causes hypotension and upper airway collapsibility. [8] Hence addition of adjuvant drugs like midazolam, ketamine or dexmedetomidine have been recommended. In our study we used either midazolam or magnesium sulfate as adjuvants to propofol.…”

Using ketamine in a patient with a near-occlusion tracheal tumor undergoing tracheal resection and reconstruction: A case report

“…Coughing and movement needed to be minimized. Ketamine provides analgesia and cough suppressant effects with minimal respiratory depression[ 8 ], and is superior to dexmedetomidine and propofol in minimizing upper airway collapse and maintaining compensatory responses to hypoxemia[ 9 ]. Adding intravenous ketamine to local anesthetic infiltration would provide better sedation and analgesia.…”