Abstract SNACC-3

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Dexmedetomidine provides better PACU hemodynamic control and reduces PACU analgesic requirements than remifentanil in intracranial tumor excision: a randomized trial

Rajan S, Hutcherson M, Yang D, Liu J, Avitsian R
Cleveland Clinic, Beachwood, OH, U.s.a

Brain tumors are responsible for 12,740 deaths in the United States every year. Anesthesia for a craniotomy poses unique challenges. An adequate level of anesthesia and analgesia during the surgery is desirable but should be followed with a rapid emergence for a timely neurologic evaluation. Remifentanil, is a popular ultra-short-acting agent with a context-sensitive half-life of about five minutes. A promising alternative is dexmedetomidine, an alpha2-adrenoceptor agonist which is gaining popularity in neuroanesthesia.
We aim to test the two primary hypotheses: A) Intraoperative administration of dexmedetomidine is at least equivalent or better than remifentanil for hemodynamic perturbations postoperatively. B) Compared to remifentanil, patients receiving dexmedetomidine require less PACU analgesics. Our secondary outcomes were comparing cognitive recovery and nursing resource usage.
Methods: 139 patients undergoing elective surgical excision of a brain tumor were randomized to either a remifentanil (Remi) or dexmedetomidine (Dex) infusion throughout surgery (71 Remi, 68 Dex)under general anesthesia. Blood pressures,heart rate, SOMCT scores(short term memory and cognitive testing) were recorded prior to surgery and in the PACU at 15, 30, 45, 60, and 90 minutes in addition to pain scores and opioid consumption.
We evaluated 139 randomized patients (68 Dexmedetomidine [Dex], 71 remifentanil [Remi]). We used a joint hypothesis testing framework to assess whether Dex was more effective than Remi (or vice versa), defined as noninferior (not worse) on both outcomes (hemodynamics and pain control) and superior on at least 1 of the 2. We tested noninferiority of Dex to Remi on PACU opioid consumption using a 1-tailed Wilcoxon rank sum test, applying a noninferiority delta equal to 20% of the combined groups median. Noninferiority on mean PACU pain score and mean arterial pressure (MAP) collapsed over time was assessed using a 1-tailed t-test from a mixed effects model, with noninferiority delta of 1 point on the VAS scale and 7.5 mmHg for MAP. After finding noninferiority on all outcomes, superiority was tested. The overall significance level was 0.05.
Hemodynamics: Dex was found to be both noninferior and superior to Remi on mean PACU MAP (P<0.001. Dex had lower more stable MAPs while Remi had higher MAPs which could be deleterious.
Pain management: Dex was found to be noninferior to Remi on PACU morphine equivalents and pain score (P <0.001, Table ). Furthermore, superiority was found on both outcomes, with median difference (97.5% CI) of -5 (-10, -3) mg for PACU morphine equivalents(P<0.001) and in pain scores, P <0.001. There was no significant group-by-time interaction on pain score (P=0.11).
Conclusions: Compared to remifentanil, administration of dexmedetomidine appears superior on PACU pain control and hemodynamic stability when used for a craniotomy.

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