Equis ISSN 2398-2977

Anesthesia: peri-operative complications - vagal reflexes

Synonym(s): Oculocardiac reflex, trigeminovagal reflex

Contributor(s): Louise Clarke, Mark Senior

Introduction

  • The oculocardiac reflex is relatively common in man where pressure or traction on the eye results in bradyarrhythmias:
    • This reflex has also been reported in horses, but is less common than in man.
    • It is initiated in the parasympathetic fibers in the nasociliary branche of the ophthalmic nerve, via the spinal tract of the trigeminal nerve.
    • The efferent limb is the vagus nerve.
  • Stimulation of the trigeminal nerve, during cannulation of the transverse facial artery, has resulted in a vagal reflex response (trigeminovagal reflex) in horses.
  • Reflex vagal responses have also been reported in anesthetized horses after stimulation of the bladder, extension of contracted joints and traction of the ovarian pedicle and spermatic cord.

Effects of vagal reflex stimulation

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Treatment

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Prevention

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Further Reading

Publications

Refereed papers
  • Klein L (1990)Anesthetic complications in the horse. Vet Clin North Am Equine Pract6, 665-692.
  • Kellagher R A & Watney G C (1986)Cardiac arrest during anaesthesia in two horses. Vet Rec119, 347-349.
  • Parviainen A K J & Trim C M (2000)Complications Associated with anaesthesia for ocular surgery: a retrospective study 1989-1996. Equine Vet J32(6) 555-559.
  • Raffe M et al(1986)Retrobulbar block in combination with general ananesthesia for equine ophthalmic surgery. Vet Surg15, 139-141.
  • Short C E & Rebhun W C (1980)Complications caused by the oculocardiac reflex during anesthesia in a foal. JAVMA176, 630-631.


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