title: Role of vagal afferents in hypotension induced by venous air embolism.
abstract: To evaluate the role of the autonomic nervous system in the development of hypotension during air embolism, we studied the effects of an intravenous bolus injection of air (0.5 ml/kg) on mean blood pressure (MBP), central venous pressure (CVP), and renal nerve activity (RNA) in urethan-anesthetized rabbits of three groups: animals with an intact neuraxis (intact group; n = 5), cervical-vagotomized animals (vagotomy group; n = 5), and sinoaortic-denervated animals (SAD group; n = 5). In the intact group, despite a significant decrease in MBP at 10 s after air injection, RNA did not increase from the preinjection level. This response of RNA was associated with a significant increase in CVP and lasted for 20 s after the injection. Vagotomized animals, however, exhibited a significant augmentation in RNA in response to a drop in MBP at 10 s after the injection. In the SAD group, profound declines in both MBP and RNA were observed at 10 s after the injection of air. Animals in these two groups showed remarkable increases in CVP. At 5 min after the air administration, MBP in the vagotomy group was significantly higher than that in the intact group. All animals in the SAD group died within 5 min of the injection. These results indicate that during hypotension induced by air injection, sympathetic activation through arterial baroreceptors may be depressed by vagal afferents emanating from cardiopulmonary receptors; the results also suggest that the arterial baroreceptor nerves may be required to overcome the lethal events that should occur during venous air embolism.
authors.affiliation: Kagawa Medical School, Department of Anesthesiology and Emergency Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Aibiki
authors.forename: S
authors.initials: S
authors.lastname: Ogura
authors.forename: K
authors.initials: K
authors.lastname: Seki
authors.forename: K
authors.initials: K
authors.lastname: Honda
authors.forename: O
authors.initials: O
authors.lastname: Umegaki
authors.forename: Y
authors.initials: Y
authors.lastname: Shirakawa
authors.forename: K
authors.initials: K
authors.lastname: Ogli
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000502:physiology; D003714:Denervation; D004618:Embolism, Air / Q000150:complications*; D007022:Hypotension / Q000209:etiology* / Q000503:physiopathology*; D009475:Neurons, Afferent / Q000502:physiology*; D011817:Rabbits; D012850:Sinus of Valsalva / Q000294:innervation; D013997:Time Factors; D014628:Vagotomy; D014630:Vagus Nerve / Q000166:cytology / Q000502:physiology*; D014680:Veins