Dexmetadomidine (Precedex) Increases Oculocardiac Reflex
Robert W. Arnold; Russell Biggs; Brion Beerle
Alaska Children’s EYE & Strabismus
Introduction: The only substances known to increase oculocardiac reflex (OCR) are fast-acting opioids(1). Last year, we reported that premedication with nasal dexmetadomidine (Precedex) was associated with more OCR. Therefore, we performed an intra-subject, intravenous comparison to test our hypothesis that this alpha-adrenergic agonist potentiates the trigemino-vagal reflex.
Methods: In our ongoing, IRB study, OCR is prospectively monitored with 10-second, square wave 200 gram tension on inferior rectus- or other muscles during strabismus surgery. Between the first and second muscle, dexmetadomidine 0.5µg/Kg I.V. was delivered.
Results: All patients had inferior rectus tension and no anticholinergic. 1399 control patients, media age 5.5 years had first OCR of -24.2±1.2% and second OCR of -22.7±1.2% with a delta (decrease) of 1.5±1.0%. The 33 patients study patients, medial age 5.6 years, had first OCR -16.0±5.6% and dexmetadomidine second OCR of -33.8±8.8% for a bradycardia augmentation of 17.8±6.8% (t-Test p<0.01).
Discussion: Similar to the impact of fentanyl, dexmetedomidine will increase the bradycardia associated with extra-ocular muscle traction- almost doubling the amount.
Conclusion: Strabismus surgeons, neonatologists and anesthesiologists need to take precautions when using Precedex.
References: (1) Chung CJ, Lee JM, Choi SR, Lee SC, Lee JH: Effect of remifentanil on oculocardiac reflex in paediatric strabismus surgery. Acta Anaesthesiol Scand 2008, 52(9):1273-1277.