Oculocardiac reflex
The oculocardiac reflex, also known as Aschner phenomenon, Aschner reflex, or Aschner-Dagnini reflex, is a decrease in pulse rate associated with traction[disambiguation needed] applied to extraocular muscles and/or compression of the eyeball. The reflex is mediated by nerve connections between the trigeminal cranial nerve and the vagus nerve of the parasympathetic nervous system. The afferent tracts are derived mainly from the ophthalmic division of the trigeminal nerve, although tracts from the maxillary and mandibular division have also been documented.[1] These afferents synapse with the visceral motor nucleus of the vagus nerve, located in the reticular formation of the brain stem. The efferent portion is carried by the vagus nerve from the cardiovascular center of the medulla to the heart, of which increased stimulation leads to decreased output of the sinoatrial node.[2] This reflex is especially sensitive in neonates and children, and must be monitored, usually by an anaesthesiologist during paediatric ophthalmological surgery, particularly during strabismus correction surgery.[3] However, this reflex may also occur with adults. Bradycardia, junctional rhythm, asystole, and very rarely death,[4] can be induced through this reflex.
Treatment/prophylaxis
The surgeon can prophylactically block the afferent limb of the reflex by injecting peribulbar or retrobulbar local anesthetics. The anesthesiologist can prophylactcally block or attenuate the efferent limb of the reflex with an intravenous injection of an anti-muscarinic acetylcholine (ACh) antagonist, such as atropine or glycopyrrolate. If bradycardia does occur, removal of the inciting stimulus is immediately indicated, and is essential for successful termination of this reflex. The surgeon, or practitioner, working on the eye should be asked to cease their activity and release the applied pressure or traction on the eyeball. This often results in the restoration of normal sinus rhythm of the heart. If not, the use of atropine or glycopyrrolate will likely successfully treat the patient and permit continuation of the surgical procedure. In extreme cases, such as the development of asystole, cardiopulmonary resuscitation may be required. Usually seen while applying traction on the medial rectus.
References
- ^ Lang S, Lanigan D, van der Wal M (1991). "Trigeminocardiac reflexes: maxillary and mandibular variants of the oculocardiac reflex". Can J Anaesth. 38 (6): 757–60. doi:10.1007/BF03008454. PMID 1914059.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Paton J, Boscan P, Pickering A, Nalivaiko E (2005). "The yin and yang of cardiac autonomic control: vago-sympathetic interactions revisited". Brain Res Brain Res Rev. 49 (3): 555–65. doi:10.1016/j.brainresrev.2005.02.005. PMID 16269319.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Kim H, Kim S, Kim C, Yum M (2000). "Prediction of the oculocardiac reflex from pre-operative linear and nonlinear heart rate dynamics in children". Anaesthesia. 55 (9): 847–52. doi:10.1046/j.1365-2044.2000.01158.x. PMID 10947746.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Smith R (1994). "Death and the oculocardiac reflex". Can J Anaesth. 41 (8): 760. doi:10.1007/BF03015643. PMID 7923532.
External links
- Reflex,+Oculocardiac at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
