An Unusual Case of Asystole Occurring during Deep Brain Stimulation Surgery

Table 1

Comparison of various etiologies of symptomatic bradycardia and hypotension.

	Venous air embolism	Trigeminal cardiac reflex	Bezold-Jarisch reflex
Incidence	Up to 4.5% in DBS surgeries [10]	Up to 18% in neurosurgery series [11]. No known prior reports in DBS surgery	No known prior reports in neurosurgery
Triggers	Trephination	Irritation of trigeminal nerve or sensory branches	Hypovolemia, spinal anesthesia leading to decrease preload
Mechanism	Entrance of air into venous system	Afferent limb, stimulation of the trigeminal nerve or sensory branches	Afferent limb, cardiac receptors via nonmyelinated type C vagal fibers
		Efferent limb, activation of vagal motor nucleus and inhibition of heart and systemic vascular system	Efferent limb, intramyocardial C fibers can potentiate a sudden withdrawal of sympathetic outflow, increasing vagal tone
Presentation	ST-T changes, right heart strain, oxygen desaturation, low end tidal CO2, coughing, wheezing, chest pain, “swoon,” and so forth	Bradycardia, hypotension, apnea, and gastric hypermotility	Bradycardia, hypotension
Predisposing factors	Sitting position, semisitting position	Use of medications (beta blockers, calcium channel blockers, sufentanil, and alfentanil), history of vagal episodes, presence of hypercapnea or hypoxemia, and light anesthesia	History of neurocardiogenic syncope, hypovolemia, medications (local anesthetic with epinephrine), sitting position, decreasing preload, and venous blood pooling
Treatment	Obtaining hemostasis, irrigation of surgical field, leveling patient’s head to right atrium in left lateral decubitus, and use of central venous catheter for aspiration of air	Increased depth of anesthesia (i.e., propofol bolus)	Immediate fluid resuscitation, vagolytics (atropine and glycopyrrolate), ondansetron, metoprolol, and ephedrine