title: Intact blood pressure, but not sympathetic, responsiveness to sympathoexcitatory stimuli in a patient with unilateral carotid body resection.
abstract: Despite rapidly growing interest in the therapeutic resection of the carotid body (CB) chemoreceptors, few physiologic studies exist on the consequences of unilateral CB resection. We present a case of an otherwise healthy postmenopausal female who underwent unilateral CB resection for a paraganglioma. Approximately 4 years postoperatively, she underwent analysis of her sympathetic and hemodynamic responses to hypoxia, lower body negative pressure, cold pressor test (CPT), and ischemic hand grip exercise and postexercise ischemia (IHE/PEI). Hypoxic ventilatory response and baroreflex sensitivity were relatively normal. Hemodynamic responses to IHE/PEI and CPT showed characteristic increases in cardiac output (from 3.9 L/min to 5.2 L/min [IHE/PEI] and 4.9 L/min [CPT]) and blood pressure (from 126/72 mmHg to 161/87 mmHg [IHE/PEI] and 171/93 mmHg [CPT]). However, muscle sympathetic nerve activity (microneurography of the peroneal nerve) decreased from baseline during IHE/PEI and CPT (burst incidence nadir of 45% and 40% of baseline, respectively) and there was no observable change in total peripheral resistance (from 24 mmHg*min/L to 22 mmHg*min/L [IHE/PEI] and 25 mmHg*min/L [CPT]). These findings illustrate intact blood pressure responsiveness despite attenuated sympathoexcitation, possibly due to an increase in cardiac output and/or adaptive inhibitory effect of the baroreflex on peripheral sympathetic activity.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Kathryn F
authors.initials: KF
authors.lastname: Larson
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Jacqueline K
authors.initials: JK
authors.lastname: Limberg
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Baker
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Joyner
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota curry.timothy@mayo.edu.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Curry
mesh_terms: D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination; D002344:Carotid Body / Q000503:physiopathology* / Q000601:surgery; D002345:Carotid Body Tumor / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D011184:Postoperative Period; D013564:Sympathetic Nervous System / Q000503:physiopathology*
keywords: Baroreflex sensitivity; carotid chemoreceptor; hypoxic ventilatory response; muscle sympathetic nerve activity