S008: VARIATION IN PERIOPERATIVE BLOOD PRESSURE WITH ADMINISTRATION OF INTRAVENOUS DEXMEDETOMIDINE FOR CATARACT SURGERY UNDER MONITORED ANESTHESIA CARE
Dylan J Shaw, BS1; Emily A Schofield, BS1; Julio A Warren, MD, FASA2; 1University of Central Florida College of Medicine; 2Department of Veterans Affairs
Introduction/Background: Dexmedetomidine is an alpha-2 adrenergic agonist that is indicated for sedation of intubated and mechanically ventilated patients in the intensive care unit and sedation of non-intubated patients prior to and/or during surgical procedures, by continuous infusion. The agent provides sedation without respiratory depression but lacks the amnestic properties of other procedural sedation drugs. Taking cost into account, dexmedetomidine is not commonly used as a first line sedative during cataract surgery. The availability of dexmedetomidine, which is not a controlled substance, has affected anesthesia provider prescribing habits during monitored anesthesia care (MAC). The most common clinically significant adverse reactions are periprocedural perturbations in blood pressure as well as bradycardia.
Methods: The medical records of all patients having cataract surgery under MAC during fiscal year (FY) 2022 at the Bay Pines Veterans Affairs Medical Center were analyzed. Data on sedative dose, pre- and post-operative vital signs, laterality, first or second procedure, age, and gender from FY 2022 were analyzed. This retrospective analysis examined perioperative blood pressure measurements in patients receiving intermittent boluses of sedative agents during cataract surgery. Descriptive statistics, logistic regression, and ANOVA analyses were conducted.
Results: 514 surgeries met the inclusion criteria of using only dexmedetomidine, only midazolam, or a combination of both sedative agents (“combination group”) during the procedure. 92.4% of the patients were male, and there was a mean decrease of 18.34 mm Hg in systolic blood pressure (SBP) among patients receiving dexmedetomidine, 9.66 mm Hg among patients receiving midazolam, and 22.88 mm Hg among patients in the combination group. There was a statistically significant difference (p<0.001) in the changes in blood pressure between midazolam and dexmedetomidine administration and a statistically significant difference (p<0.001) in the changes in blood pressure between midazolam and the combination group. There was not a statistically significant difference (p=0.212) in the changes in blood pressure between dexmedetomidine and the combination group. Logistic regression analyses showed a mean SBP decrease of 1 mm Hg per 2.84 μg of dexmedetomidine (p<0.001), 0.59 mg of midazolam (p=0.006), and 6.21 years of increased age (p=0.020).
Discussion/Conclusion: Cataract surgery is usually short in duration, and patients may receive a variety of sedative agents. The use of benzodiazepines during this procedure is common but has the potential for delirium in elderly patients. Alternate sedatives including dexmedetomidine are used increasingly in elderly populations to avoid benzodiazepine use, but this is not without risk. This analysis found that severe perturbations in vital signs occur and are not infrequent in veterans receiving intermittent boluses of dexmedetomidine for sedation, with and without midazolam. Our study finds that total doses higher than 20 μg of dexmedetomidine in patients greater than 70 years old resulted in severe changes in SBP (>30 mm Hg decrease) and that dexmedetomidine caused far larger shifts in SBP than that of midazolam alone (Figure 1). Further clinical research should focus on the effects of sedation with intermittent boluses of dexmedetomidine on vital signs for other invasive procedures.